期刊文献+

二次检索

题名
关键词
文摘
作者
第一作者
机构
刊名
分类号
参考文献
作者简介
基金资助
栏目信息

年份

学科

共找到1,192篇文章
< 1 2 60 >
每页显示 20 50 100
Carboniferous-Early Permian heterogeneous distribution of porous carbonate reservoirs in the Central Uplift of the South Yellow Sea Basin and its hydrocarbon potential analysis
1
作者 Shu-yu Wu Jun Liu +4 位作者 Jian-wen Chen Qi-liang Sun Yin-guo Zhang Jie Liang Yong-cai Feng 《China Geology》 2025年第1期58-76,共19页
Mesozoic-Palaeozoic marine carbonate rocks are crucial hydrocarbon reservoirs in the Central Uplift area of the South Yellow Sea Basin(SYSB).Due to the scarcity of boreholes and the significant heterogeneity of carbon... Mesozoic-Palaeozoic marine carbonate rocks are crucial hydrocarbon reservoirs in the Central Uplift area of the South Yellow Sea Basin(SYSB).Due to the scarcity of boreholes and the significant heterogeneity of carbonate reservoirs,the distribution of porous carbonate reservoirs and their related key controlling factors remain unclear.In this study,factors affecting the distribution of porous Carboniferous-Early Permian carbonate reservoirs in the SYSB were investigated through seismic inversion and isotope analysis.The log-seismic characteristics of porous carbonate reservoirs,sensitive lithology parameters,and physical property parameters were extracted and analyzed.The pre-stack simultaneous inversion technique was applied to predict the lithology and physical properties of porous carbonate reservoirs.Moreover,the sedimentary of carbonate was analyzed using isotopes of carbon,oxygen,and strontium.The results show that porous carbonate reservoirs are mainly developed in the open platform sediments with porosities of 3%-5%and are mainly distributed in the paleo-highland(Huanglong Formation and Chuanshan Formation)and the slope of paleo-highland(Hezhou Formation).The porous carbonate reservoirs of the Qixia Formation are only locally developed.In addition,the negativeδ13C excursions indicate a warm and humid tropical climate with three sea-level fluctuations in the study area from the Carboniferous to Early Permian.The favorable conditions for developing porous carbonate rocks include the sedimentary environment and diagenetic process.The primary pore tends to form in high-energy environments of the paleo-highland,and the secondary pore is increased by dissolution during the syngenetic or quasi-syngenetic period.According to the hydrocarbon potential analysis,the Late Ordovician Wufeng Formation and Lower Silurian Gaojiabian Formation are the source rocks in the high-maturity-over-maturity stage,the Carboniferous-Lower Permian carbonate is the good reservoirs,and the Late Permian Longtan-Dalong Formation is the stable seal,ensuring a huge hydrocarbon accumulation potential in SYSB.The methods proposed in this study can be applied to other carbonate-dominated strata worldwide. 展开更多
关键词 Sedimentary Heterogeneous porous carbonate reservoirs C-H-Sr isotope analysis Carboniferous-Early Permian Chuanshan formation Huanglong formation Pre-stack simultaneous inversion technique Oil-gas exploration engineering Hydrocarbon accumulation Hydrocarbon potential Central Uplift of the South Yellow Sea Basin
下载PDF
Possible Habitats for NH_(3),NH_(2)D,H^(13)CN,HC^(15)N,SO,and C^(18)O in the Initial Conditions of High-mass Star Formation
2
作者 Quan-Ling Cui Chuan-Peng Zhang Jun-Jie Wang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第4期237-252,共16页
The initial condition of high-mass star formation is a complex area of study because of the high densities(n_(H_(2))>106cm^(-3))and low temperatures(T_(dust)<18 K)involved.Under such conditions,many molecules be... The initial condition of high-mass star formation is a complex area of study because of the high densities(n_(H_(2))>106cm^(-3))and low temperatures(T_(dust)<18 K)involved.Under such conditions,many molecules become depleted from the gas phase by freezing out onto dust grains.However,the N-bearing and deuterated species could remain gaseous under these extreme conditions,suggesting that they may serve as ideal tracers.In this paper,using the Plateau de Bure Interferometer and Very Large Array observations at 1.3 mm,3.5 mm,and 1.3 cm,we investigate the possible habitats for NH_(3),NH_(2)D,H^(13)CN,HC^(15)N,SO,and C^(18)O in eight massive precluster and protocluster clumps G18.17,G18.21,G23.97N,G23.98,G23.44,G23.97S,G25.38,and G25.71.We found that the NH3cores are in good agreement with the 3.5 mm peak emission,but the NH_(3)is much more extended than the 3.5 mm emission structure.The SO distributions agree well with the 3.5 mm peaks for the evolved star formation stage,but we did not detect any SO emission in the four earliest star formation sources.C^(18)O is a poor tracer in conditions of the cold(■18 K)and dense(■10^(4)cm^(-3))cores,e.g.,the prestellar cores.We also found that the NH_(2)D cores are mainly located in the temperature range of 13.0-20.0 K,and the NH_(2)D lines may be strongly depleted above 20 K. 展开更多
关键词 galaxies:star formation techniques:interferometric methods:observational
下载PDF
Pre-Drilling Prediction Techniques on the High-Temperature High-Pressure Hydrocarbon Reservoirs Offshore Hainan Island,China 被引量:2
3
作者 ZHANG Hanyu LIU Huaishan +6 位作者 WU Shiguo SUN Jin YANG Chaoqun XIE Yangbing CHEN Chuanxu GAO Jinwei WANG Jiliang 《Journal of Ocean University of China》 SCIE CAS CSCD 2018年第1期72-82,共11页
Decreasing the risks and geohazards associated with drilling engineering in high-temperature high-pressure(HTHP) geologic settings begins with the implementation of pre-drilling prediction techniques(PPTs). To improve... Decreasing the risks and geohazards associated with drilling engineering in high-temperature high-pressure(HTHP) geologic settings begins with the implementation of pre-drilling prediction techniques(PPTs). To improve the accuracy of geopressure prediction in HTHP hydrocarbon reservoirs offshore Hainan Island, we made a comprehensive summary of current PPTs to identify existing problems and challenges by analyzing the global distribution of HTHP hydrocarbon reservoirs, the research status of PPTs, and the geologic setting and its HTHP formation mechanism. Our research results indicate that the HTHP formation mechanism in the study area is caused by multiple factors, including rapid loading, diapir intrusions, hydrocarbon generation, and the thermal expansion of pore fluids. Due to this multi-factor interaction, a cloud of HTHP hydrocarbon reservoirs has developed in the Ying-Qiong Basin, but only traditional PPTs have been implemented, based on the assumption of conditions that do not conform to the actual geologic environment, e.g., Bellotti's law and Eaton's law. In this paper, we focus on these issues, identify some challenges and solutions, and call for further PPT research to address the drawbacks of previous works and meet the challenges associated with the deepwater technology gap. In this way, we hope to contribute to the improved accuracy of geopressure prediction prior to drilling and provide support for future HTHP drilling offshore Hainan Island. 展开更多
关键词 pre-drilling prediction techniques formation PORE pressure high-temperature high-pressure hydrocarbon RESERVOIRS HAINAN Island Ying-Qiong Basin
下载PDF
Age,growth and reproduction of Sarcocheilichthys nigripinnis from the Qingyi Stream in the Huangshan Mountains 被引量:3
4
作者 Yunzhi YAN Yinsheng XU +2 位作者 Ling CHU Shah HE Yifeng CHEN 《Zoological Research》 CAS CSCD 北大核心 2012年第3期I0025-I0031,共7页
Identifying the life-history strategies of fish and their associations with the surrounding environment is the basic foundation in the conservation and sustainable utilization of fish species.We examined the age,growt... Identifying the life-history strategies of fish and their associations with the surrounding environment is the basic foundation in the conservation and sustainable utilization of fish species.We examined the age,growth,and reproduction of Sarcocheilichthys nigripinnis using 352 specimens collected monthly from May 2009 to April 2010 in the Qingyi Stream.We found the sex ratio of this study population was 0.58:1(female:male),significantly different from expected 1:1.Females and males both comprised four age groups.The annuli on the scales were formed during February and March.No obvious between-sex difference was observed in length-weight and length-scale-radius relationships.The total length in back-calculation significantly increased with age for both sexes,but did not differ significantly at each age between the two sexes.An inflection point was observed in the growth curves given by the von Bertalanffy growth function for total weight.At this inflection point,fish were 3.95 years.Both sexes reach their 50% sex maturity at age 2,when females and males were 94.7 mm and 103.0 mm total length.The temporal pattern of the gonado-somatic index corresponded to a spawning period that occurred from April through July.The non-synchronicity of egg diameter in each mature ovary during the breeding period suggested these fish may be batch spawners.The absolute fecundity increased significantly with total length and weight,whereas no significant correlation was observed between the relative fecundity and body size. 展开更多
关键词 Sarcocheilichthys nigripinnis Age structure Annulus formation Sexual maturity Spawning period Reproductive investment
下载PDF
The application of combined gravity and seismic data formation separation for revealing deep structure 被引量:2
5
作者 WeiYan Yang Zhanjun 《Applied Geophysics》 SCIE CSCD 2006年第4期255-259,共5页
In some oilfields with 3D seismic data, the deeper structure cannot be observed due to poor quality deep seismic data. Layer stripping using both seismic and gravity data is a solution for this problem but it cannot g... In some oilfields with 3D seismic data, the deeper structure cannot be observed due to poor quality deep seismic data. Layer stripping using both seismic and gravity data is a solution for this problem but it cannot get satisfactory results because the horizontal variations in formation density are ignored. We present a variable-density formation separation technique to address this problem. Based on 3D seismic depth data and laterallyvariable density derived from 3D seismic velocity data, the upper formation gravity effect is calculated by forward modeling and removed from the Bouguer gravity. The formation-separated gravity anomaly with variable density is obtained, which mainly reflects the deeper geological structure. In block XX of North Africa, the shallow formations seismic data is excellent but the data at the top of basement is poor. The formation-separated gravity anomaly processed under the control of 3D seismic data fits well with the known seismic interpretation and wells. It makes the geological interpretation more reliable. 展开更多
关键词 formation separation technique variable-density
下载PDF
Construction of well logging knowledge graph and intelligent identification method of hydrocarbon-bearing formation 被引量:1
6
作者 LIU Guoqiang GONG Renbin +4 位作者 SHI Yujiang WANG Zhenzhen MI Lan YUAN Chao ZHONG Jibin 《Petroleum Exploration and Development》 CSCD 2022年第3期572-585,共14页
Based on the well logging knowledge graph of hydrocarbon-bearing formation(HBF),a Knowledge-Powered Neural Network Formation Evaluation model(KPNFE)has been proposed.It has the following functions:(1)extracting charac... Based on the well logging knowledge graph of hydrocarbon-bearing formation(HBF),a Knowledge-Powered Neural Network Formation Evaluation model(KPNFE)has been proposed.It has the following functions:(1)extracting characteristic parameters describing HBF in multiple dimensions and multiple scales;(2)showing the characteristic parameter-related entities,relationships,and attributes as vectors via graph embedding technique;(3)intelligently identifying HBF;(4)seamlessly integrating expertise into the intelligent computing to establish the assessment system and ranking algorithm for potential pay recommendation.Taking 547 wells encountered the low porosity and low permeability Chang 6 Member of Triassic in the Jiyuan Block of Ordos Basin,NW China as objects,80%of the wells were randomly selected as the training dataset and the remainder as the validation dataset.The KPNFE prediction results on the validation dataset had a coincidence rate of 94.43%with the expert interpretation results and a coincidence rate of 84.38%for all the oil testing layers,which is 13 percentage points higher in accuracy and over 100 times faster than the primary conventional interpretation.In addition,a number of potential pays likely to produce industrial oil were recommended.The KPNFE model effectively inherits,carries forward and improves the expert knowledge,nicely solving the robustness problem in HBF identification.The KPNFE,with good interpretability and high accuracy of computation results,is a powerful technical means for efficient and high-quality well logging re-evaluation of old wells in mature oilfields. 展开更多
关键词 well logging hydrocarbon bearing formation identification knowledge graph graph embedding technique intelligent identification neural network
下载PDF
THE FORMATION MECHANISM OF PORTLAND CEMENT CLINKER MINERALS IN RAPID BURNING
7
作者 胡曙光 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 1992年第3期26-34,共9页
Cement clinker is burnt at the rapid heating rate has the obvious effect of saving energy due to the low burning temperature and short burning time. This kind of technique is being researched actively in recent years,... Cement clinker is burnt at the rapid heating rate has the obvious effect of saving energy due to the low burning temperature and short burning time. This kind of technique is being researched actively in recent years, but the systematical theory investigation about the formation mechanism of clinker minerals under this condition has not been reported. In this paper, the formation mechanism of Portland cement clinker minerals in rapid burning was studied by means of DTA, SEM, EPMA, XRD and other conventional testing methods by using a special burning equipment. 展开更多
关键词 rapid burning fast heating technique formation mechanism cement clinker
下载PDF
The Cementing Techniques Of Salt Formation
8
作者 Zeng yijin Ding shidong Xia Huade (Petroleum Drilling Reseach Institute,MGMR) 《西部探矿工程》 CAS 1993年第5期6-12,共7页
This paper analyzes mechnasim of casing failure and collapse by salt formation,discusses cementing techniques of salt zone about casing programme, casing design, preparation of well condition, mud and slurry propertie... This paper analyzes mechnasim of casing failure and collapse by salt formation,discusses cementing techniques of salt zone about casing programme, casing design, preparation of well condition, mud and slurry properties required, cementing technology, and puts forward the measures for solving problems posed when cementing through salt sequences, and illustrates with examples. 展开更多
关键词 SALT formation CEMENTATION COLLAPSE strenghth PLASTIC flow saturated SLURRY SYNTHETIC techniques
下载PDF
Age,growth and reproduction of Sarcocheilichthys nigripinnis from the Qingyi Stream in the Huangshan Mountains
9
作者 Yunzhi YAN Yinsheng XU +2 位作者 Ling CHU Shan HE Yifeng CHEN 《Zoological Research》 SCIE CAS CSCD 北大核心 2012年第S01期25-31,共7页
Identifying the life-history strategies of fish and their associations with the surrounding environment is the basic foundation in the conservation and sustainable utilization of fish species.We examined the age,growt... Identifying the life-history strategies of fish and their associations with the surrounding environment is the basic foundation in the conservation and sustainable utilization of fish species.We examined the age,growth,and reproduction of Sarcocheilichthys nigripinnis using 352 specimens collected monthly from May 2009 to April 2010 in the Qingyi Stream.We found the sex ratio of this study population was 0.58:1(female:male),significantly different from expected 1:1.Females and males both comprised four age groups.The annuli on the scales were formed during February and March.No obvious between-sex difference was observed in length-weight and length-scale-radius relationships.The total length in back-calculation significantly increased with age for both sexes,but did not differ significantly at each age between the two sexes.An inflection point was observed in the growth curves given by the von Bertalanffy growth function for total weight.At this inflection point,fish were 3.95 years.Both sexes reach their 50%sex maturity at age 2,when females and males were 94.7 mm and 103.0 mm total length.The temporal pattern of the gonado-somatic index corresponded to a spawning period that occurred from April through July.The non-synchronicity of egg diameter in each mature ovary during the breeding period suggested these fish may be batch spawners.The absolute fecundity increased significantly with total length and weight,whereas no significant correlation was observed between the relative fecundity and body size. 展开更多
关键词 Sarcocheilichthys nigripinnis Age structure Annulus formation Sexual maturity Spawning period Reproductive investment
下载PDF
Sperm chromatin structure assay (SCSA): a tool in diagnosis and treatment of infertility 被引量:36
10
作者 Mona Bungum Leif Bungum Aleksander Giwercman 《Asian Journal of Andrology》 SCIE CAS CSCD 2011年第1期69-75,共7页
Diagnosis of male infertility has mainly been based on the World Health Organization (WHO) manual-based semen parameter's concentration, motility and morphology. It has, however, become apparent that none of these ... Diagnosis of male infertility has mainly been based on the World Health Organization (WHO) manual-based semen parameter's concentration, motility and morphology. It has, however, become apparent that none of these parameters are reliable markers for evaluation of the fertility potential of a couple. A search for better markers has led to an increased focus on sperm chromatin integrity testing in fertility work-up and assisted reproductive techniques. During the last couple of decades, numerous sperm DNA integrity tests have been developed. These are claimed to be characterized by a lower intraindividual variation, less intralaboratory and interlaboratory variation and thus less subjective than the conventional sperm analysis. However, not all the sperm chromatin integrity tests have yet been shown to be of clinical value. So far, the test that has been found to have the most stable clinical threshold values in relation to fertility is the sperm chromatin structure assay (SCSA), a flow cytometric test that measures the susceptibility of sperm DNA to acid-induced DNA denaturation in situ. Sperm DNA fragmentation as measured by SCSA has shown to be an independent predictor of successful pregnancy in first pregnancy planners as well as in couples undergoing intrauterine insemination, and can be used as a tool in investigation, counseling and treatment of involuntary childlessness. More conflicting data exist regarding the role of sperm DNA fragmentation in relation to fertilization, pre-embryo development and pregnancy outcome in in vitro fertilization and intracytoplasmic sperm injection (ICSI). 展开更多
关键词 assisted reproductive techniques INFERTILITY sperm chromatin structure assay sperm DNA
下载PDF
Comparative study on efficacy of three sperm-separation techniques 被引量:3
11
作者 LanXU Ren-KangLU +1 位作者 LingCHEN Yan-LuanZHENG 《Asian Journal of Andrology》 SCIE CAS CSCD 2000年第2期131-134,共4页
Aim: To evaluate the comparative effectiveness of real-time sperm separation technique (Wang's tube method) andother two conventional methods in isolating high-quality sperm preparation, and to compare the spouse ... Aim: To evaluate the comparative effectiveness of real-time sperm separation technique (Wang's tube method) andother two conventional methods in isolating high-quality sperm preparation, and to compare the spouse pregnancy ratein intrauterine insemination (IUI) with sperm preparations isolated by these methods. Methods: The effectivenessof the real-time sperm separation technique, the conventional swim-up and the Percoll discontinuous density gradientmethods in isolating sperm preparations from 60 infertile patients (20 with apparently normal semen and 40, abnormalsemen contaminated with microorganisms and other impurities) was evaluated and compared. The microorganisms to beremoved included bacteria, vires, Chlamydia trachomaticum, Ureaplsama urealyticum, etc. The spouse pregnancyrates in IUI with sperm preparations isolated by these three techniques from 80 oligoasthenoteratospermic patients werealso compared. Results: The quality (including the percentages of normal form, normal-chromatin and motilesperm, and the grade of motility) of sperm obtained by the real-time sperm separation technique was much higher ( P< 0.01) as compared with those by the other two methods. The Wang's tube method was also more effective in remov-ing microorganisms and other impurities. The method provided a higher IUI pregnancy rate than the other two spermseparation techniques ( P < 0.05). Conclusion: The real-time sperm separation technique is the most effectivemethod so far available in isolating high-quality sperm samples to be used in assisted reproduction. 展开更多
关键词 techmiques real-time sperm separation technique swim-up method Percoll gradient method Wang's tube reproduction
下载PDF
The evolution of stellar metallicity gradients of the Milky Way disk from LSS-GAC main sequence turn-off stars: a two-phase disk formation history? 被引量:2
12
作者 Mao-Sheng Xiang Xiao-Wei Liu +8 位作者 Hai-Bo Yuan Yang Huang Chun Wang Juan-Juan Ren Bing-Qiu Chen Ning-Chen Sun Hua-Wei Zhang Zhi-Ying Huo Alberto Rebassa-Mansergas 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2015年第8期1209-1239,共31页
Accurate measurements of stellar metallicity gradients in the radial and vertical directions of the disk and their temporal variations provide important constraints on the formation and evolution of the Milky Way disk... Accurate measurements of stellar metallicity gradients in the radial and vertical directions of the disk and their temporal variations provide important constraints on the formation and evolution of the Milky Way disk. We use 297 042 main sequence turn-off stars selected from the LAMOST Spectroscopic Survey of the Galactic Anticenter(LSS-GAC) to determine the radial and vertical gradients of stellar metallicity,△[Fe/H]/△R and △[Fe/H]/△|Z | of the Milky Way disk in the direction of the anticenter. We determine ages of those turn-off stars by isochrone fitting and measure the temporal variations of metallicity gradients. We have carried out a detailed analysis of the selection effects resulting from the selection, observation and data reduction of LSS-GAC targets and the potential biases of a magnitude limited sample on the determinations of metallicity gradients. Our results show that the gradients, both in the radial and vertical directions, exhibit significant spatial and temporal variations. The radial gradients yielded by stars with the oldest ages( 11 Gyr) are essentially zero at all heights from the disk midplane, while those given by younger stars are always negative. The vertical gradients deduced from stars with the oldest ages( 11 Gyr)are negative and only show very weak variations with Galactocentric distance in the disk plane, R, while those yielded by younger stars show strong variations with R.After being essentially flat at the earliest epochs of disk formation, the radial gradients steepen as age decreases, reaching a maximum(steepest) at age 7–8 Gyr, and then they flatten again. Similar temporal trends are also found for the vertical gradients. We infer that the assembly of the Milky Way disk may have experienced at least two distinct phases. The earlier phase is probably related to a slow, pressure-supported collapse of gas, when the gas settles down to the disk mainly in the vertical direction. In the later phase, there are significant radial flows of gas in the disk, and the rate of gas inflow near the solar neighborhood reaches a maximum around a lookback time of 7–8 Gyr.The transition between the two phases occurs around a lookback time between 8 and11 Gyr. The two phases may be responsible for the formation of the Milky Way's thick and thin disks, respectively. Also, as a consequence, we recommend that stellar age is a natural, physical criterion to distinguish stars from the thin and thick disks. From an epoch earlier than 11 Gyr to one between 8 and 11 Gyr, there is an abrupt, significant change in magnitude of both the radial and vertical metallicity gradients, suggesting that stellar radial migration is unlikely to play an important role in the formation of the thick disk. 展开更多
关键词 Galaxy: abundances—Galaxy: disk—Galaxy: evolution Galaxy: formationtechniques spectroscopic
下载PDF
Generation of Monoclonal Antibody to Porcine Reproductive and Respiratory Syndrome Virus GP4 Protein and Identification of Its Minic Epitopes
13
作者 Liu Peng Yuan Qing +7 位作者 Li Wei-qun Yin Xue-ting Ghulam Abbas Li Peng-chong Zhang Chao-fan Huang Xiao-dan Zhang Rui-li Li Guang-xing 《Journal of Northeast Agricultural University(English Edition)》 CAS 2019年第2期49-59,共11页
Porcine reproductive and respiratory syndrome virus(PRRSV)GP4 protein was prokaryotically expressed,and used as an antigen to immunize six-week-old BALB/c female mice.With conventional cell fusion method,an anti-PRRSV... Porcine reproductive and respiratory syndrome virus(PRRSV)GP4 protein was prokaryotically expressed,and used as an antigen to immunize six-week-old BALB/c female mice.With conventional cell fusion method,an anti-PRRSV GP4 protein monoclonal antibody(Mab)5F12 was successfully prepared.It was identified as IgG2b subclass and had better stability and specificity,which not only responded with recombinant PRRSV GP4 protein,but also with PRRSV.Phage display technique had varieties of applications,in particular,the identification of key antigen epitopes for the development of therapeutic and diagnostic reagents and vaccines.In this study,Mab-5F12 was used as the target for biopanning a 12-mer phage random peptide library.After four rounds of biopanning,two phage-displayed peptides,named P-A and P-G(AKFEVCSPVVLG and GVNQENMLHFSF)were identified that recognized Mab-5F12 specifically.Sequence analysis showed that one or more of the peptides exhibited partial sequence similarity to the native GP4 protein sequence,which corresponded to 69-80 and 84-95 aa segments of the HP-PRRSV GP4 protein.Furthermore,real-time quantitative RT-PCR and indirect immunofluorescence assay indicated consistently the abilities of P-A and P-G to block viral infection in Marc-145 cells and they could function as antiviral agents for PRRSV. 展开更多
关键词 porcine REPRODUCTIVE and respiratory syndrome virus(PRRSV) GP4 protein MONOCLONAL antibody PHAGE display technique VIRAL infection
下载PDF
Influence of Characteristics of Alumina-silicate Raw Materials on the Formation Process of Clinker
14
作者 王亚丽 CUI Suping +2 位作者 LAN Mingzhang TIAN Guiping LIU Lingling 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2014年第5期966-971,共6页
The traditional alumina-silicate raw materials, for example, clays, in the precalcining technique of cement production, have been replaced by low grade and high silica content sandstones, shales, and industrial waste ... The traditional alumina-silicate raw materials, for example, clays, in the precalcining technique of cement production, have been replaced by low grade and high silica content sandstones, shales, and industrial waste residues, including fly ashes, slag, and others. The results are the change of compositions and characteristics of raw materials applied and a great effect on cement calcination process and clinker formation. In this work, the cement clinker formation process of different alumina-silicate raw materials to replace clay raw material was studied by chemical analysis, X-ray diffraction, differential thermal analysis, and high temperature microscope based on the characteristics of the alumina-silicate raw materials. The formation heat of the clinker was determined by the acid dissolution method. Influence of different alumina-silicate raw materials on the clinker burnability and formation process was studied. The results show that the changing of alumina- silicate raw materials, especially using industrial waste residues, can reduce the formation temperature of high temperature liquid phases, improve the burnability of raw materials, reduce the formation temperature and formation heat of clinker. And this study also observed the formation temperature and transformation of high temperature liquid phases in the heating process of raw materials by high temperature microscope. 展开更多
关键词 precalcining technique of cement production alumina-silicate raw materials burnability of raw materials high temperature liquid phase formation heat of clinker
下载PDF
Anti-Müllerian Hormone and Its Utility in Cattle Reproduction
15
作者 Garza Arredondo Aimé Jazmín Moreno Degollado Gustavo +4 位作者 Adolfo-Soto Dominguez Pérez Hernández Raymundo Alejandro Rosales S. Cedillo Zamora-Ávila Diana Castillo-Velázquez Uziel 《Open Journal of Veterinary Medicine》 CAS 2023年第1期1-11,共11页
Reproductive biotechnologies offer us greater possibilities to improve animal genetics. However, the success of these depends on different factors such as the proper selection of the donor female. For this reason, end... Reproductive biotechnologies offer us greater possibilities to improve animal genetics. However, the success of these depends on different factors such as the proper selection of the donor female. For this reason, endocrine markers have been used to evaluate the ovarian reserve, which allow a successful selection of donors. Recent research has shown, among other things, that concentrations greater than 0.130 ng/mL of anti-Mullerian hormone (also known as Muller-inhibiting substance, which is a member of the transforming growth factor beta superfamily of growth and differentiation factors) are related to donors of more than fifteen transferable embryos. Therefore, this review describes studies showing that the measurement of anti-Müllerian hormone concentrations, before superovulation programs, reduces the costs per embryo produced. 展开更多
关键词 AMH Anti-Müllerian Hormone Reproductive techniques Follicular Population Granulosa Cells SUPEROVULATION
下载PDF
The HI gas and star formation in star-forming galaxies selected from ALFALFA
16
作者 Feng-Jie Lei Hong Wu +2 位作者 Yi-Nan Zhu Man ILam Zhi-Min Zhou 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2021年第5期207-222,共16页
This paper presents the results of Hαimaging of 169 galaxies randomly selected from the α.40-SDSS catalog.The sample has excluded all low surface brightness galaxies (LSBGs) whose central surface brightness in B ban... This paper presents the results of Hαimaging of 169 galaxies randomly selected from the α.40-SDSS catalog.The sample has excluded all low surface brightness galaxies (LSBGs) whose central surface brightness in B band (μ0(B)) fainter than 22.5 mag arcsec-2.It can be used as the counterparts sample to LSBGs.We observed their Hα and R band images by using the 2.16 m telescope at the Xinglong Observatory of the National Astronomical Observatories,Chinese Academy of Sciences (NAOC).The main goal of this work is to present the properties of those galaxies,together with Hαflux and star formation-,gas-,stellar mass-surface density.In addition,we confirm the correlations among HI content,stellar mass and star formation in ALFALFA galaxies.The HI mass increases with stellar mass,and the slope slows down at the higher stellar mass.The overall trend was that the specific star formation rate (s SFR) decreases with stellar mass,and the sSFR dropped sharply when the stellar mass is close to 1010.3~1010.5M⊙.The weak correlation between SFR/MHIand MHIimplies the HI contribute little to star formation.Our sample,which are mostly star-forming galaxies,follows the revisited Kennicutt-Schmidt law as well as the Kennicutt-Schmidt law. 展开更多
关键词 techniques:image processing galaxies:star formation catalogs
下载PDF
Heterotopic pregnancy after assisted reproductive techniques with favorable outcome of the intrauterine pregnancy:A case report
17
作者 Ya-Nan Wang Lian-Wen Zheng +2 位作者 Lu-Lu Fu Ying Xu Xue-Ying Zhang 《World Journal of Clinical Cases》 SCIE 2023年第3期669-676,共8页
BACKGROUND Heterotopic pregnancy(HP)is a rare condition in which both ectopic and intrauterine pregnancies occur.HP is uncommon after natural conception but has recently received more attention due to the widespread u... BACKGROUND Heterotopic pregnancy(HP)is a rare condition in which both ectopic and intrauterine pregnancies occur.HP is uncommon after natural conception but has recently received more attention due to the widespread use of assisted reproductive techniques(ART)such as ovulation promotion therapy.CASE SUMMARY Here,we describe a case of HP that occurred after ART with concurrent tubal and intrauterine singleton pregnancies.This was treated successfully with surgery to preserve the intrauterine pregnancy,resulting in the birth of a low-weight premature infant.This case report aims to increase awareness of the possibility of HP during routine first-trimester ultrasound examinations,especially in pregnancies resulting from ART and even if multiple intrauterine pregnancies are present.CONCLUSION This case alerts us to the importance of comprehensive data collection during regular consultations.It is important for us to remind ourselves of the possibility of HP in all patients presenting after ART,especially in women with an established and stable intrauterine pregnancy that complain of constant abdominal discomfort and also in women with an unusually raised human chorionic gonadotropin level compared with simplex intrauterine pregnancy.This will allow symptomatic and timeous treatment of patients with better results. 展开更多
关键词 Heterotopic pregnancy Assisted reproductive techniques Preterm labor Premature rupture of membranes Case report
下载PDF
Sequential clustering of star formations in IC 1396
18
作者 Ya-Fang Huang Jin-Zeng Li 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2013年第5期557-570,共14页
We present a comprehensive study of the H II region IC 1396 and its star forming activity, in which multi-wavelength data ranging from the optical to the near- and far-infrared were employed. The surface density distr... We present a comprehensive study of the H II region IC 1396 and its star forming activity, in which multi-wavelength data ranging from the optical to the near- and far-infrared were employed. The surface density distribution of all the 2MASS sources with a certain detection toward IC 1396 indicates the existence of a compact cluster spatially consistent with the position of the exciting source of the H II region, HD 206267. The spatial distribution of the sources with excessive infrared emission, selected based on archived 2MASS data, reveals the existence of four sub-clusters in this region. One is associated with the open cluster Trumpler 37. The other three are found to be spatially coincident with the bright rims of the H II region. All the sources with excessive emission in the near infrared are cross-identified with AKARI IRC data. An analysis of the spectral energy distributions (SEDs) of the resultant sample leads to the identification of eight CLASS I, 15 CLASS II and 15 CLASS IH sources in IC 1396. Optical identification of the sample sources with R magnitudes brighter than 17 mag corroborates the results from the SED analysis. Based on the spatial distribution of the infrared young stellar objects at different evolutionary stages, the surrounding sub-clusters located in the bright rims are believed to be younger than the central one. This is consistent with a scenario of sequential star formation in this region. Imaging data of a dark patch in IC 1396 by Herschel SPIRE, on the other hand, indicate the presence of two far-infrared cores in LDN 1111, which are likely to be a new generation of protostellar objects in formation. So we infer that the star formation process in this H II region was not continuous but rather episodic. 展开更多
关键词 techniques photometric -- stars: formation -- stars: pre-main sequence-- infrared: stars
下载PDF
A compound spike model for formation of nuclear tracks in solids
19
作者 Mukhtar Ahmed RANA 《Nuclear Science and Techniques》 SCIE CAS CSCD 2007年第6期349-353,共5页
Formation of nuclear tracks in solids has been described as a thermal spike as well as a Coulomb explo- sion spike.Here,formation of nuclear tracks is described as a compound spike including partial roles of both ther... Formation of nuclear tracks in solids has been described as a thermal spike as well as a Coulomb explo- sion spike.Here,formation of nuclear tracks is described as a compound spike including partial roles of both thermal and Coulomb explosion spikes in track formation.Fractional roles of both spikes depend on atomic and electronic structure of a track detector and deposited energy density in the track detector by the incident charged particle.Be- havior of the cylindrical zone along the path of the incident particle is described mathematically in terms of bulk and individual atomic flow or movement.Defect structure of the latent nuclear tracks is described and conditions of con- tinuity and discontinuity of latent tracks are evaluated and discussed.This paper includes mathematical description, analysis and evaluation of the nuclear track formation issue in the light of published experimental and theoretical re- sults,which are useful for users of nuclear track detection technique and researchers involved in ion beam induced materials modification and ions implantation in semiconductors. 展开更多
关键词 核子轨道探测技术 晶体 固态径迹探测 探测方法
下载PDF
辅助生殖技术中妊娠结局预测模型的研究进展
20
作者 王聪 宫政 +3 位作者 马赛花 胡凯元 郎梦然 夏天(审校) 《国际生殖健康/计划生育杂志》 2025年第1期30-35,共6页
辅助生殖技术(assisted reproductive technology,ART)妊娠结局受多种因素影响,而传统基于临床经验的评估方式存在主观性和不准确性,临床预测模型(clinical prediction model,CPM)通过综合分析多模态变量因子可提高评估的准确性和治疗... 辅助生殖技术(assisted reproductive technology,ART)妊娠结局受多种因素影响,而传统基于临床经验的评估方式存在主观性和不准确性,临床预测模型(clinical prediction model,CPM)通过综合分析多模态变量因子可提高评估的准确性和治疗安全性,有助于实现精准医疗。目前,基于多样化算法构建了多种预测妊娠结局的CPM,不仅包括传统的逻辑回归算法,还扩展到新型的非线性机器学习算法,如随机森林、神经网络和深度学习算法。最新临床研究进展表明,基于多样化算法构建的CPM在ART领域预测妊娠结局方面展现出较高的准确性和实际应用潜力。进一步研究可以通过收集更多样化和具有代表性的临床数据、优化模型算法、开展多中心合作、提升CPM的泛化能力,构建更准确可靠的CPM。 展开更多
关键词 生殖技术 辅助 妊娠结局 逻辑回归 机器学习 临床预测模型
下载PDF
上一页 1 2 60 下一页 到第
使用帮助 返回顶部