期刊文献+
共找到437篇文章
< 1 2 22 >
每页显示 20 50 100
Pollen Grain Germination and Pollen Tube Growth in Pistil of Rice 被引量:3
1
作者 CHEN Shi-qiang WANG Zhong LIU Man-xi XIE Zhao-wei WANG Hui-hui 《Rice science》 SCIE 2008年第2期125-130,共6页
The germination of pollen grain in vitro and the growth of pollen tube in the pistil of rice were observed with a microscope. The stigma was removed at different time points after pollination to study its effect on se... The germination of pollen grain in vitro and the growth of pollen tube in the pistil of rice were observed with a microscope. The stigma was removed at different time points after pollination to study its effect on seed setting rate. The rice pollen grain started to germinate at 2 min after pollination and the pollen tube penetrated stigma into style in 5-10 min, 30 min later the end of pollen tube reached the bottom of ovary, and only some pollen tubes arrived at embryo sac at 40 min after pollination. Meanwhile, a small amount of callose began to deposit in the pollen tubes, a great deal of callose was observed at 50 min after pollination, whereas the pollen grain began to shrink. The growing rates of pollen tube in the rice stigma, style and ovary were 1500, 5000, and 5400 μm/h, respectively. The seed setting rate was quite low when the stigma was removed at about 10-15 min after pollination, gradually increased when it removed at 20 min to 50 min after pollination, and over 60% when it removed at 50 min after pollination and finally tended to be stable. 展开更多
关键词 RICE pollen grain germination pollen tube growth seed setting rate microscopic observation
下载PDF
Inositol (1,4,5)-triphosphate Modulates Pollen Tube Polar Growth
2
作者 刘群录 MONTEIRO David MALHO'Rui 《Journal of Shanghai Jiaotong university(Science)》 EI 2005年第S1期1-7,18,共8页
In this article, the functions of D-myo-inositol-1,4,5-trisphosphate (Ins [1,4,5] P3) in regulating pollen tube polar growth were investigated by application of caged version of the phosphoinositides. To increase the ... In this article, the functions of D-myo-inositol-1,4,5-trisphosphate (Ins [1,4,5] P3) in regulating pollen tube polar growth were investigated by application of caged version of the phosphoinositides. To increase the intracellular Ins(1,4,5)P3 concentration at the apical region of pollen tube, the caged Ins(1,4,5)P3 loaded by osmotic shock was activated by 10 s 360 nm UV flash at this domain (10 μm from the tip). More than 70% pollen tubes were induced swelling at apex and/or growth axis reorientation, accompanying temporarily growth arrest, by localized increase of Ins(1,4,5)P3 concentration (n=21). While, pollen tubes without being loaded with caged Ins(1,4,5)P3 had not response to the same dosage UV flash. With FM 1-43 fluorescent staining, it was found that growth perturbation by UV activated caged Ins(1,4,5)P3 had tight link with membrane trafficking at the apical zone of pollen tubes. Upon UV pulse, the apical V-shaped bright area where was full of secretory vesicles spread to a much broader region, which implied that actin filaments at the apical region were remodeled. It was also observed that the FM 1-43 fluorescence intensity at tip remarkably increased than that before UV flash, which demonstrated that more secretory vesicles were accumulated at this region. To estimate the role of Ins(1,4,5)P3 in modulating intracellular calcium concentration and distribution, dextran conjugated fluorescent dye Calcium Green-1 and Rhodamine B were microinjected into pollen tubes together with caged Ins(1,4,5)P3. The results showed that calcium concentration at the subapical region increased upon UV released Ins(1,4,5)P3. Consequently, the tip-focused calcium gradient under the apical dome of pollen tube was disturbed. Simultaneously, the pollen tube bulged at the apical region and its growth rate decreased. As the tip-focused calcium gradient was reestablished, the pollen tube morphology and growth recovered to the normal level. Therefore, Ins(1,4,5)P3 can modulate pollen tube growth rate and direction through mobilizing intracellular calcium and regulating vesicle trafficking during pollen tube finding its way to the ovary. 展开更多
关键词 pollen tube polar growth CALCIUM Ins(1 4 5)P_(3)
下载PDF
Influence of Plant Growth Regulators on Pollen Germination and Growth of Xinjiang Apricots 被引量:6
3
作者 孙慧瑛 廖康 +3 位作者 安晓芹 成小龙 刘娟 邱晨 《Agricultural Science & Technology》 CAS 2013年第2期262-268,共7页
[Objective] This study aimed to investigate the influence of different plant growth regulators on apricot pollen germination and pollen tube growth. [Method] Pollens of six kinds of Xinjiang apricots were cultured in ... [Objective] This study aimed to investigate the influence of different plant growth regulators on apricot pollen germination and pollen tube growth. [Method] Pollens of six kinds of Xinjiang apricots were cultured in solid media supplemented with five plant growth regulators (GA3 , NAA, 2, 4-D, 6-BA, IAA). Then the rate of pollen germination and the length of pollen tube were respectively measured. [Result] In a certain concentration range, GA3 most significantly promoted the pollen germination and the pollen tube growth of Shushanggan, Kalayulvke, Dayoujia, Yiliakeyulvke and Kabakehuanna; NNA had the strongest improvement function on Kumaiti’s pollen germination and pollen tube growth. [Conclusion] All the five plant growth regulators promoted the pollen germination and the pollen tube growth of apricots at low concentration but inhibited them at high concentration. 展开更多
关键词 APRICOT Plant growth regulators Pollen germination Pollen tube growth
下载PDF
Effects of Sodium Chloride Stress on Growth of Sweet Potato Plantlets in vitro and Ion Content 被引量:13
4
作者 高叶 赵术珍 +2 位作者 陈敏 宋晓征 王宝山 《Agricultural Science & Technology》 CAS 2008年第5期27-30,共4页
[Objective] This study aimed to investigate the salt-tolerance mechanism of sweet potato.[Method]Two sweet potato varieties of Xu 25-2(salt-tolerant cultivar)and Triumph 100(salt-sensitive cultivar)were treated by sod... [Objective] This study aimed to investigate the salt-tolerance mechanism of sweet potato.[Method]Two sweet potato varieties of Xu 25-2(salt-tolerant cultivar)and Triumph 100(salt-sensitive cultivar)were treated by sodium chloride with the concentration of 0 mmol/L and 100 mmol/L.After 20 days,Na+ content and Na+/K+ ratio in the roots,shoots and leave were determined by the flame photometer,while dry weight and fresh weight of roots,shoots and leave in different varieties were also studied.[Result]The growth of two sweet potato varieties was inhibited under salt stress,so the plant became shorter,leaf and root became fewer,dry weight of roots and leave decreased,but seedlings of Xu 25-2 were inhibited slightly.Furthermore,Na+ content and Na+/K+ ratio in roots,shoots and leaves of two sweet potato varieties increased.Na+ content of salt-tolerant Xu 25-2 was low in roots,shoots and leaves,while Na+ content of salt-sensitive Triumph 100 was high in shoots and leave of seedlings,but the change range of Xu 25-2 was less than that of Triumph 100.[Conclusion]The lower Na+ content and Na+/K+ ratio in leaves under salt stress were the most important characteristics for salt-tolerance of sweet potato varieties. 展开更多
关键词 SALT STRESS Sweet potato Test-tube PLANTLET growth Ion content SALT tolerance
下载PDF
Undercooling and solidification of Ni_(77)P_(23) alloy in a 52-m drop tube 被引量:1
5
作者 李工 高云鹏 +2 位作者 孙懿楠 迟照洪 刘日平 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第9期3412-3416,共5页
This paper applies techniques of containerless processing, drop tube and glass fluxing, to undercool and solidify Ni77P23 alloys. Different diameter spheres were collected at the bottom of a 52-m long drop tube. Both ... This paper applies techniques of containerless processing, drop tube and glass fluxing, to undercool and solidify Ni77P23 alloys. Different diameter spheres were collected at the bottom of a 52-m long drop tube. Both crystalline and amorphous phase were formed in various size specimens due to the different cooling rate. The variation of partial undercooling with bulk undercooling is calculated for the Ni77P23 alloys. The deep undercooling and rapid solidification behaviour of Ni77P23 melts has been analysed with respect to microstructure formation and transition during fluxing and 52-m drop process of undercooled melts. 展开更多
关键词 crystal morphology growth models drop tube
下载PDF
Fast and Accurate Identification of <i>M. tuberculosis</i>Complex Using an Immunochromatographic MPT64 Antigen Detection Test 被引量:2
6
作者 Anto Jesuraj Uday Kumar Hiresave Srinivasa 《Journal of Tuberculosis Research》 2015年第4期149-156,共8页
Background: A new rapid Immunochromatographic test (ICT) kit (MPT64 TB Ag Kit) for detection of MPT64 Antigen in M. tuberculosis (MTB) isolates used for rapid identification of MTB isolates developed by SD (Standard D... Background: A new rapid Immunochromatographic test (ICT) kit (MPT64 TB Ag Kit) for detection of MPT64 Antigen in M. tuberculosis (MTB) isolates used for rapid identification of MTB isolates developed by SD (Standard Diagnostics) Bio line, South Korea was evaluated. The ICT is a rapid, reliable and cheaper method that can be used instead of conventional biochemical tests for confirming MTB in culture isolates in resource limited laboratories. The study also evaluated the ability of ICT to detect MPT64-Antigen before the micro MGIT could signal positive. Material/Methods: A total of 450 sputum samples of individual patients were used for the study. 152 isolates of Mycobacteria were recovered from solid and liquid media. These strains were tested for the detection of MPT64-antigen. H37Rv strain was served as the positive reference control and also used for early detection of Antigen experiment. Findings: The development of bands on both test and sample region when H37Rv strain was tested were seen (MPT64 antigen positive). When 138 MTB isolates were tested, it showed a similar banding pattern indicating 100% sensitivity. MPT64 band formation was not detected in any of the 14 isolates indicating 100% specificity. Both PPV & NPV were 100%. All the isolates negative for MPT64 Ag were confirmed as MOTT by conventional bio-chemical PNBA. The H37Rv strain showed a faint band from the 2nd day onwards from inoculation till 3rd day in the earlier Antigen detection experiment. Conclusion: Rapid identification of MTB culture isolate is a pressing need for diagnosis and proceeding to perform drug susceptibility testing. MPT64 TB Ag detection ICT kit is a rapid, reliable method, good substitute for molecular identification methods, and conventional biochemical test which is time-consuming and technically demanding. The early detection of Antigen can be used as an effective tool in diagnosis. 展开更多
关键词 MTB (M. tuberculosis) MOTT (Mycobacteria Other than M. tuberculosis) PNBA (Para Nitro Benzoic Assay) MPT64 Antigen ICT (Immunochromatography Test) MGIT (Mycobacterium growth Indicator tube) SD TB Ag MPT64 Rapid (Standard Diagnostics Seoul South Korea)
下载PDF
Characterization of mycobacterium isolates from pulmomary tuberculosis suspected cases visiting Tuberculosis Reference Laboratory at Ethiopian Health and Nutrition Research Institute,Addis Ababa Ethiopia:a cross sectional study
7
作者 Biniam Mathewos Nigatu Kebede +2 位作者 Tesfu Kassa Adane Mihret Muluwork Getahun 《Asian Pacific Journal of Tropical Medicine》 SCIE CAS 2015年第1期35-40,共6页
Objective:To characterize mycobaclerium isolates from pulmomary tuberculosis suspected cases visiting National Tuberculosis Reference Laboratory at Ethiopian Health and Nutrition Research Institute,for diagnosis of pu... Objective:To characterize mycobaclerium isolates from pulmomary tuberculosis suspected cases visiting National Tuberculosis Reference Laboratory at Ethiopian Health and Nutrition Research Institute,for diagnosis of pulmonary tuberculosis from January 4 to February 22.2010 with total samples of 263.Methods:Sputum specimens were collected and processed:the deposits were cultured.Por culturing Lowenstein Jensen medium(LJ) and Mycobacteria Growth Indicator Tube(BACTEC MGIT 960) were used.Capilia Neo was used for detecting NTM isolates from isolates of BACTEC MGIT960.In Armauer Hansen Research Institute,Addis Ababa Ethiopia,Deletion typing PCR method for species identification(from confirmed Mycobacterium tuberculosis complex(MTBC) isolates by Capilia Neo) uas done.Results:Out of 263 enrolled in the study.124 and 117 ol them were positive for mycobaeterium growth by BACTEC MGIT 960 and 1.1 culture method,respectively.From BACTEC MGIT 960 positive media of 124 isolates.117 were randomly taken to perform Capilia TB Neo lest.From these 7(6%) of them were found to be NTM and 110(94%) were MTBC.From these 110 MTBC isolates,81 of them were randomly taken and run by the deletion typing RD9 PCR method of molecular technique.Out of these 78(96.3%) were found to be species of Mycobacterium tuberculosis and 3(3.7%) were found to be not in the MTBC.Regarding the types of methods of culture media.Mycobacteria Growth Indicator Tube(BACTEC MGIT 960) method was found to have excellent agreement(with kappa value ol 0.78) with the routine method of LJ.Conclusions:Pulmonary tuberculosis suspected cases visiting the National Tuberculosis Reference Laboratory at EHNR1 that were confirmed to be pulmonary tuberculosis are caused by the species of Mycobacterium tuberculosis.hence treatment regimen including pyrazinamide can be applied to the patients as the first choice in the study area in Addis Ababa.Ethiopia.There is indication of the presence of NTM in patients visiting the tuberculosis reference laboratory and this is important because NTM is known lo cause pulmonary disease similar with sign and symptom ol pulmonary tuberculosis but different in treatment.BACTEC MGIT 960 has excellent agreement with LJ media but it has high tendency of having high contamination rale unless a better decontamination method is designed. 展开更多
关键词 NTM MYCOBACTERIUM tubeRCULOSIS complex MYCOBACTERIA growth indicator tube Lowenstein Jensen media
下载PDF
FAILURES AND THE LIFE OF FURNACE TUBES
8
作者 F.Z.Shen Y.Ding +4 位作者 D.M.Hou Z.P.Ning Y.Lü T.B.Dong A.R.Tuohuti 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2004年第4期419-425,共7页
It is showed after the furnace tubes serviced for 8-10 years that the density of damage in the HAZ (heat affected zone) of the weld has higher than in parent metals, though the depth of damage is not equal to. By the ... It is showed after the furnace tubes serviced for 8-10 years that the density of damage in the HAZ (heat affected zone) of the weld has higher than in parent metals, though the depth of damage is not equal to. By the test of creep crack growth, it is also acquired that under same mechanic parameter C* (t), the rate of creep crack growth in the HAZ is more than twice as fast as in parent metals. Two mechanisms (overheating and thermal shock) of failure occurred in an accident are presented. The stress of thermal shock is analyzed, in which the change of the elasticity modulus with the radius ET = /(r) is considered. Based on it, the safety region of the thermal shock is obtained. Finally, two sets of curves for the safe life are suggested which can facilitate to estimate the remaining life of HK-40 or HP-Nb tubes by their creep rupture data. 展开更多
关键词 FAILURE thermal stock creep crack growth remaining life furnace tube
下载PDF
Effects and mechanism of miRNA-24 on the proliferation,migration and tube formation of vascular endothelial cells
9
作者 Xiaojing Tao Feng Shen +5 位作者 Peng Yang Xuelan Luo Dan Li Yuanyuan Yan Yongxiong Zhong Hesheng Ou 《广西医科大学学报》 CAS 2018年第7期901-906,共6页
Objective:To investigate the effect and mechanism of miRNA-24 on the proliferation,migration and tube formation of vascular endothelial cells.Methods:Human umbilical vein endothelial cells(HUVECs)were assigned into co... Objective:To investigate the effect and mechanism of miRNA-24 on the proliferation,migration and tube formation of vascular endothelial cells.Methods:Human umbilical vein endothelial cells(HUVECs)were assigned into control,microRNA(miR)-24 overexpression and anti-miR-24 groups.The proliferation and migration abilities of HUVECs were detected by methyl thiazolyl tetrazolium(MTT)assay and scratch wound healing assay,respectively.The ability of HUVECs to form tubular structures was evaluated by a tube formation assay.The mRNA and protein expressions of vascular endothelial growth factor(VEGF)and transcription factor Sp1 were determined by RT-PCR,immunocytochemistry and western blotting,respectively.Results:The miR-24 overexpression group exhibited decreased cell proliferation and migration,and expressions of VEGF and Sp1 compared with the control group(P <0.01).No tube-like network structure was formed in the miR-24 overexpression group.However,inhibition of miR-24 in HUVECs markedly increased cell proliferation and migration,enhanced tube formation and expressions of VEGF and Sp1(P<0.05 or P<0.01).Conclusion:MiR-24 suppressed the proliferation,migration and tube formation of HUVECs,and the mechanism might be related to the down-regulation of VEGF expression.Sp1 might participate in this regulation process. 展开更多
关键词 miRNA-24 vascular endothelial growth factor SP1 endothelial cells tube formation
下载PDF
Synthesis, structural characterization and formation mechanism of giant-dielectric CaCu3Ti4O12 nanotubes
10
作者 Nirupam Banerjee Saluru Baba Krupanidhi 《Natural Science》 2010年第7期688-693,共6页
A capillary-enforced template-based method has been applied to fabricate calcium copper titanate (CaCu3Ti4O12, CCTO) nanotubes (diameter ~200 nm) by filling sol-gel CCTO precursor solution into the nanochannels of por... A capillary-enforced template-based method has been applied to fabricate calcium copper titanate (CaCu3Ti4O12, CCTO) nanotubes (diameter ~200 nm) by filling sol-gel CCTO precursor solution into the nanochannels of porous anodic aluminum oxide (AAO) templates, subsequent heating for phase formation and fi- nally the removal of nano-channel templates by applying basic solution. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) equipped with Energy-dispersive X-ray spectroscopy (EDX) have been employed to characterize the morphology, structure, and composition of as-prepared nanotubes. XRD and selected-area electron diffraction (SAED) in-vestigations demonstrated that postannealed (750○C for 1 h) CCTO nanotubes were poly-crystalline with a cubic pseudo-perovskite cry- stal structure. The FE-SEM and TEM results showed that CCTO nanotubes were of uniform diameter (~200 nm) throughout their length. High resolution TEM (HRTEM) analysis confirm- ed that the obtained CCTO nanotubes are made of randomly aligned nano-particles 5-10 nm in size. EDX analysis demonstrated that stoichi- ometric CaCu3Ti4O12 was formed. The possible formation mechanism of CCTO nanotubes in the AAO template is discussed. 展开更多
关键词 Nano-tubes Sol-Gel TEMPLATED growth High-K-Dielectrics
下载PDF
Design and Calculation for Test Tube with the Aim of Regulation Simultaneous Crystallization Tests
11
作者 Aco Janicijevic Nebojsa Danilovic Branislav Cabric 《Journal of Crystallization Process and Technology》 2012年第3期121-123,共3页
A design for an air-cooled test tube, with a series of modular and movable rings (cylindrical “crystallization comb”), installed in a laboratory crucible furnace is presented. The setup allows easy regulation simult... A design for an air-cooled test tube, with a series of modular and movable rings (cylindrical “crystallization comb”), installed in a laboratory crucible furnace is presented. The setup allows easy regulation simultaneous crystallization tests of a series of different crystallization rates in several columns (matrix) of test tubes, enabling fast studies of obtaining crystals. This low-budget, portable device (i.e. adjustable airstream with more simple control options), can also be applied in tube and chamber furnaces. The relations between the crystallization rate and parameters of air-cooled test tube are given and numerically analyzed. 展开更多
关键词 Technique for Crystal growth DESIGN and CALCULATION Test tube—Cylindrical CRYSTALLIZATION COMBS CRYSTALLIZATION Clusters—Obtaining Crystals from MELT
下载PDF
Small interfering RNA targeting PGC-1α inhibits VEGF expression and tube formation in human retinal vascular endothelial cells 被引量:6
12
作者 Jian Jiang Lu Zhang Xiao-Bo Xia 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2015年第5期877-883,共7页
AIMTo determine whether small interfering RNA (siRNA) of PGC-1&#x003b1; could inhibit vascular endothelial growth factor (VEGF) expression and tube formation in human retinal vascular endothelial cells (hRVECs).ME... AIMTo determine whether small interfering RNA (siRNA) of PGC-1&#x003b1; could inhibit vascular endothelial growth factor (VEGF) expression and tube formation in human retinal vascular endothelial cells (hRVECs).METHODShRVECs transfected with peroxisome proliferator-activated receptor-&#x003b3; coactivator-1&#x003b1; (PGC-1&#x003b1;) siRNA were incubated for 24h and then placed into a normoxic (20%, O<sub>2</sub>) or hypoxic (1%, O<sub>2</sub>) environment for another 16h. PGC-1&#x003b1; mRNA and protein levels were detected by real-time PCR and Western blot. VEGF mRNA and protein levels were detected by real-time PCR and ELISA. Cell proliferation was evaluated by BrdU incorporation assay. Forty-eight hours after siRNA transfection, hRVECs were planted into Matrigel-coated plates and cultured under normoxic (20%, O<sub>2</sub>) or hypoxic (1%, O<sub>2</sub>) conditions for another 48h. The tube formation of hRVECs was observed under an optical microscope and quantified by counting the number of branch points and calculating the total tube length.RESULTSPGC-1&#x003b1; mRNA and protein levels were significantly reduced by PGC-1&#x003b1; siRNA, and VEGF mRNA and protein levels also decreased significantly. The percentage of BrdU-labeled cells in siPGC-1&#x003b1; groups were significantly decreased compared with control siRNA groups under normoxia and hypoxia in cell proliferation assay. In the tube formation assay, PGC-1&#x003b1; siRNA treated cells formed significantly fewer tubes.CONCLUSIONBlocking PGC-1&#x003b1; expression can inhibit VEGF expression in hRVECs and inhibit their ability to form tubes under both normoxic and hypoxic conditions. 展开更多
关键词 peroxisome proliferator-activated receptor-γ coactivator-1α vascular endothelial growth factor small interfering RNA retinal vascular endothelial cell tube formation
下载PDF
强制对流下翅片管蒸发器表面结霜实验
13
作者 陈清华 陆育 +2 位作者 关维娟 季家东 王建刚 《河南科技大学学报(自然科学版)》 CAS 北大核心 2024年第1期19-26,34,M0003,共10页
翅片管蒸发器表面结霜是阻碍制冷系统高效运行的主要不利因素之一。利用恒温恒湿箱搭建强制对流下蒸发器翅片管表面结霜可视化实验平台,在环境温度0~8℃、相对湿度55%~75%及迎面风速0.8~2.4 m/s时,实时记录霜层动态生长过程,研究了环境... 翅片管蒸发器表面结霜是阻碍制冷系统高效运行的主要不利因素之一。利用恒温恒湿箱搭建强制对流下蒸发器翅片管表面结霜可视化实验平台,在环境温度0~8℃、相对湿度55%~75%及迎面风速0.8~2.4 m/s时,实时记录霜层动态生长过程,研究了环境温度、相对湿度和迎面风速对霜层生长特性及蒸发器换热性能的影响规律。结果表明:环境温度和迎面风速是影响蒸发器结霜的主要因素,结霜50 min,环境温度为0℃的霜层厚度比环境温度为8℃的提高了12.78%,迎面风速为2.4 m/s的霜层厚度比迎面风速为0.8 m/s的提高了14.66%,结霜量与换热量提高趋势相同。在结霜初期,相对湿度越大,换热量越大;结霜后期,相对湿度越小,换热量越大,并得到了换热量关于环境参数与时间的相关关系。 展开更多
关键词 翅片管蒸发器 可视化 结霜 霜层生长 强制对流
下载PDF
水稻花粉管生长及其对非生物逆境胁迫的响应机理研究进展
14
作者 许用强 徐军 +4 位作者 奉保华 肖晶晶 王丹英 曾宇翔 符冠富 《中国水稻科学》 CAS CSCD 北大核心 2024年第5期495-506,共12页
水稻是我国乃至全世界最为重要的粮食作物之一。全球气候变暖背景下,高温、干旱、低温寡照等极端天气频繁发生,水稻产量品质形成受到不同程度的影响,严重威胁我国的粮食安全。花粉管在雌蕊组织中的生长是水稻生殖生长最为关键的过程,高... 水稻是我国乃至全世界最为重要的粮食作物之一。全球气候变暖背景下,高温、干旱、低温寡照等极端天气频繁发生,水稻产量品质形成受到不同程度的影响,严重威胁我国的粮食安全。花粉管在雌蕊组织中的生长是水稻生殖生长最为关键的过程,高温等非生物逆境胁迫可严重干扰花粉管生长的信号传递和能量代谢,进而导致水稻受孕失败。因此,研究高温等逆境胁迫影响水稻花粉管生长及其调控机制具有重要意义。本文综述了水稻花粉管生长的基本过程,包括信号传递以及能量代谢,同时阐述了高温、干旱、低温寡照、重金属等逆境影响花粉管生长致使小穗败育的作用机制及其栽培调控技术,为减缓高温等逆境胁迫干扰水稻花粉管生长,提高水稻授粉受孕能力的栽培技术提供理论参考,并对今后的研究方向进行展望。 展开更多
关键词 水稻 逆境胁迫 花粉管生长 响应机理 调控措施
下载PDF
振动作用下平直翅片管结霜初期微液滴运动过程数值模拟
15
作者 关维娟 陈清华 +3 位作者 张斌 季家东 王建刚 刘萍 《振动与冲击》 EI CSCD 北大核心 2024年第8期155-161,共7页
平直翅片管换热器在低温高湿环境中工作极易发生结霜现象,造成能耗增加、故障率升高,而对结霜初期的微液滴施加振动作用可以加速微液滴的滑落过程从而达到抑制结霜的效果。对结霜前期微液滴的生长过程进行数值模拟分析,并通过文献值验... 平直翅片管换热器在低温高湿环境中工作极易发生结霜现象,造成能耗增加、故障率升高,而对结霜初期的微液滴施加振动作用可以加速微液滴的滑落过程从而达到抑制结霜的效果。对结霜前期微液滴的生长过程进行数值模拟分析,并通过文献值验证了数值模拟的可靠性,然后利用不同时刻的微液滴数据,通过数值模拟的方式,研究不同振动频率作用下微液滴的运动特性,最后搭建试验平台进行验证。研究结果发现,不同体积的微液滴对应的最优振动频率有所不同,当微液滴体积较小时,较高的振动频率使微液滴在基管壁面来回振荡,不易滑落,当微液滴体积较大时,较高的振动频率有利于微液滴克服壁面摩擦力,有利于液滴滑落。 展开更多
关键词 制冷系统 平直翅片管 微液滴生长 振动抑霜
下载PDF
攸县油茶远缘杂交亲和性的解剖学研究
16
作者 叶佳伟 高晓磊 +2 位作者 周璇 袁德义 邹锋 《江西农业大学学报》 CAS CSCD 北大核心 2024年第3期558-571,共14页
【目的】为了探究攸县油茶(Camellia yuhsienensis)远缘杂交亲和性的生物学机制。【方法】研究以石果毛蕊山茶[C.mairei var.lapidea(Y.C.Wu)Sealy](SG)、海南油茶‘海油3号’(C.hainanica‘Haiyou 3’)(HN-3)和普通油茶‘德油6号’(C.o... 【目的】为了探究攸县油茶(Camellia yuhsienensis)远缘杂交亲和性的生物学机制。【方法】研究以石果毛蕊山茶[C.mairei var.lapidea(Y.C.Wu)Sealy](SG)、海南油茶‘海油3号’(C.hainanica‘Haiyou 3’)(HN-3)和普通油茶‘德油6号’(C.oleifera‘Deyou 6’)(DY-6)为父本,采用常规授粉和混合授粉方式对攸县油茶(YX)进行自交和杂交授粉。采用流式细胞仪测定亲本倍性,通过离体萌发法测定父本花粉活力,运用显微技术观察花粉萌发及花粉管生长动态以及早期果实和胚珠发育动态,并田间调查各授粉组合的座果率和落果率。【结果】(1)YX为六倍体,SG为二倍体,HN-3为八倍体,DY-6为六倍体。(2)4种油茶花粉具有较强的活力和育性,其中花粉活力最高的是DY-6,为70.13%;花粉活力最低的是YX,为40.68%。(3)自交和杂交所有组合的花粉均能在柱头上正常萌发,且花粉管在授粉后12 h均生长到花柱基部,但自交和YX×SG的花粉管进入子房后生长受阻,无法到达胚珠;YX×HN-3和YX×DY-6的花粉管则在授粉后72h到达胚珠。(4)自交和杂交授粉后100 d内,YX×DY-6的果实横径、纵径最大,YX×SG的果实横径、纵径最小;YX×DY-6的败育胚珠数最少,平均为3.83枚/果;YX×SG的败育胚珠数最多,平均为6.00枚/果。(5)自交和杂交授粉后100 d内,YX×DY-6的座果率最高,为68.0%;YX×SG的座果率最低,为4.0%;YX×HN-3的座果率为16.0%,其落果高峰主要集中在授粉后0~30 d和40~70 d;混合授粉组合YX×SD的座果率为22.0%。【结论】自交和YX×SG的杂交障碍主要为受精前障碍,YX×HN-3的杂交障碍为受精前和受精后障碍;攸县油茶远缘杂交亲和性也与亲本倍性有关,其亲和性大小为YX(六倍体)×DY-6(六倍体)>YX×HN-3(八倍体)>YX×YX>YX×SG(二倍体);混合授粉方式能在一定程度上提高攸县油茶远缘杂交亲和性。研究结果为攸县油茶远缘杂交亲和性机理研究提供了细胞学基础,也为油茶远缘杂交育种工作提供理论参考。 展开更多
关键词 攸县油茶 远缘杂交 亲和性 花粉管生长 座果率
下载PDF
分析发育支持性护理干预联合标准化微量喂养对新生儿睡眠质量和发育情况的影响
17
作者 许欣欣 王玉华 潘燕婷 《世界睡眠医学杂志》 2024年第4期819-822,共4页
目的:分析发育支持性护理干预联合标准化微量喂养对新生儿睡眠质量和发育情况的影响。方法:选取2022年5月至2023年5月福建省石狮市总医院收治的新生儿80例作为研究对象,按照随机数字表法分为对照组和观察组,每组40例。对照组给予常规护... 目的:分析发育支持性护理干预联合标准化微量喂养对新生儿睡眠质量和发育情况的影响。方法:选取2022年5月至2023年5月福建省石狮市总医院收治的新生儿80例作为研究对象,按照随机数字表法分为对照组和观察组,每组40例。对照组给予常规护理干预,观察组给予发育支持性护理联合标准化微量喂养支持干预。采用匹兹堡睡眠质量指数(PSQI)比较2组新生儿睡眠质量的差异,同时比较2组新生儿的生长发育情况及喂养不耐受持续时间、达全肠喂养时间、达纠正胎龄体质量时间以及鼻胃管留置时间。结果:干预后,观察组PSQI评分显著低于对照组,观察组新生儿喂养不耐受持续时间、达全肠喂养时间、达纠正胎龄体质量时间以及鼻胃管留置时间均低于对照组,观察组新生儿体质量、头围、身高、上臂围发育水平均高于对照组,差异均有统计学意义(均P<0.05)。结论:发育支持性护理联合标准化微量喂养是一种有效应对新生儿喂养不耐受和改善睡眠质量的方法。该方法通过优化喂养策略和睡眠环境,能够显著提高新生儿的喂养和睡眠适应能力,提高新生儿发育水平,值得临床推广应用。 展开更多
关键词 发育支持性护理 标准化微量喂养 新生儿 喂养不耐受 睡眠质量 生长发育 鼻胃管留置 应用效果
下载PDF
导流筒的底部结构对直拉单晶硅氧含量的影响
18
作者 王新强 景华玉 +4 位作者 王小亮 刘利国 周涛 万军军 张正 《新技术新工艺》 2024年第3期63-66,共4页
采用STR公司研发的专业晶体生长软件CGSim,对热场内的导流筒部件的底部结构进行优化。研究了导流筒底部的两个结构:一是导流筒底部水平结构长度(X值);二是导流筒底部结构倾斜长度(Y值)。研究结果表明,通过调整导流筒底部的结构,改变了... 采用STR公司研发的专业晶体生长软件CGSim,对热场内的导流筒部件的底部结构进行优化。研究了导流筒底部的两个结构:一是导流筒底部水平结构长度(X值);二是导流筒底部结构倾斜长度(Y值)。研究结果表明,通过调整导流筒底部的结构,改变了熔体内的温度分布,增大了自由液面下方的对流强度,加快了氧杂质的挥发,降低了氧杂质传输分凝到晶棒的氧含量。结果表明,随着X值增加,生长界面的氧含量就越低;随着Y值增加,生长界面的氧含量无明显变化。由此得知,导流筒底部X值是影响晶棒生长界面氧含量的关键结构;而Y值对氧含量影响作用较弱。模拟结果显示,当X值为160 mm时,氧含量最大降低0.57 ppma。 展开更多
关键词 导流筒 氧杂质 生长界面 分凝 自由液面
下载PDF
中药多途径治疗对输卵管阻塞性不孕症患者术后输卵管复通率、血清CTGF水平及子宫动脉血流的影响 被引量:1
19
作者 白珍珍 孟慧玲 于迎新 《临床和实验医学杂志》 2024年第3期281-285,共5页
目的 探究中药多途径治疗对输卵管阻塞性不孕症患者术后输卵管复通率、血清结缔组织生长因子(CTGF)水平及子宫动脉血流的影响。方法 采用前瞻性研究,选取2020年12月至2022年12月沧州市妇幼保健院收治的104例输卵管阻塞性不孕症患者作为... 目的 探究中药多途径治疗对输卵管阻塞性不孕症患者术后输卵管复通率、血清结缔组织生长因子(CTGF)水平及子宫动脉血流的影响。方法 采用前瞻性研究,选取2020年12月至2022年12月沧州市妇幼保健院收治的104例输卵管阻塞性不孕症患者作为研究对象,按照随机数字表法将其分为观察组和对照组,每组各52例。对照组患者采用宫腹腔镜进行手术治疗,观察组在对照组手术治疗的基础上给予中药多途径治疗(包括中药汤剂口服治疗、中药保留灌肠治疗和中药离子导入治疗3种方式)。比较两组患者的中医证候积分、输卵管复通率、实验室指标[CTGF和白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)]和子宫内膜容受性指标[宫内膜动脉阻力指数(RI)、搏动指数(PI)、内膜厚度、内膜类型]情况。结果 治疗后,两组患者的下腹胀痛、白带、输卵管畅通度和舌脉等中医证候积分均较治疗前降低,且观察组患者的各项中医证候积分分别为(1.46±0.34)、(0.88±0.43)、(1.71±0.44)、(1.46±0.43)分,均显著低于对照组[(3.17±0.62)、(1.77±0.61)、(2.56±0.78、(2.29±0.66)分],差异均有统计学意义(P<0.05)。观察组患者的输卵管复通率为96.15%,显著高于对照组(80.77%),差异有统计学意义(P<0.05)。与治疗前相比,治疗后,两组血清CTGF、IL-6和TNF-α水平均显著降低,且观察组患者的血清CTGF、IL-6和TNF-α水平分别为(2.24±0.52)μg/L、(0.91±0.22)pg/mL、(41.33±6.27)pg/mL,均显著低于对照组[(2.81±0.88)μg/L、(1.47±0.46)pg/mL、(60.14±9.84)pg/mL],差异均有统计学意义(P<0.05)。观察组患者的RI、PI、子宫内膜厚度和子宫内膜A型,子宫内膜容受性指标差值分别为0.49±0.13、0.51±0.11、(1.84±0.20)mm、(24.15±2.96)%,均高于对照组[0.20±0.09、0.25±0.07、(1.27±0.15)mm、(14.56±2.04)%],差异均有统计学意义(P<0.05)。结论 中药多途径治疗能够有效改善输卵管阻塞性不孕症患者的临床症状,提高患者的输卵管复通率,降低血清CTGF水平,改善子宫动脉血流,值得临床推广应用。 展开更多
关键词 中药多途径用药治疗 输卵管阻塞性不孕症 输卵管复通率 结缔组织生长因子 子宫动脉血流
下载PDF
生长管中过饱和度在不同构建方式下的分布特性 被引量:7
20
作者 于燕 徐俊超 +2 位作者 张军 孟强 钟辉 《东南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2016年第4期733-738,共6页
为了研究水汽相变中不同构建方式形成的细颗粒长大所需的过饱和环境,利用变物性参数传热传质模型对生长管中过饱和度水平进行了预测,并评价了2种过饱和构建方式:低温饱和气流与高温热水相接触(方式1);高温饱和气流与低温冷水相接触(方式... 为了研究水汽相变中不同构建方式形成的细颗粒长大所需的过饱和环境,利用变物性参数传热传质模型对生长管中过饱和度水平进行了预测,并评价了2种过饱和构建方式:低温饱和气流与高温热水相接触(方式1);高温饱和气流与低温冷水相接触(方式2).同时分析了进气温度、管壁水温度、进气流速和压力对2种构建方式下所得过饱和度的影响.结果表明:变物性与定物性参数下预测过饱和水平有一定的差异性,最大差异性体现在生长管中心线处;方式2获得的过饱和分布较为均匀;气流与水温差较低时,方式1所得平均过饱和度大;温差较高时,方式2所得平均过饱和度大;温差相同时,较低的温度水平更有利于提高生长管中过饱和水平;压力和进气流速的增加有利于生长管过饱和水平均匀化. 展开更多
关键词 过饱和度 传热传质 生长管 水汽相变
下载PDF
上一页 1 2 22 下一页 到第
使用帮助 返回顶部