期刊文献+
共找到219篇文章
< 1 2 11 >
每页显示 20 50 100
Analysis of Volatile Constituents in Lonicera japonica Thunb. from Different Origins by GC-MS 被引量:11
1
作者 杜成智 冯旭 +2 位作者 王卉 吴玲 李盼 《Agricultural Science & Technology》 CAS 2015年第5期1081-1083,1087,共4页
[Objective] This study aimed to analyze the volatile constituents in Lonicera japonica Thunb. from different origins. [Method] HP-5MS capillary columns were used and column temperature was controlled by a program. MS ... [Objective] This study aimed to analyze the volatile constituents in Lonicera japonica Thunb. from different origins. [Method] HP-5MS capillary columns were used and column temperature was controlled by a program. MS analysis was performed with EI and quadruple mass analyzer. The volatile constituents in L. japonica Thunb. were identified by NIST02 and Wiley275 libraries, and their relative contents were determined with chromatographic peak area normalization method. [Result] According to GC-MS total ion-current chromatograms, 35 volatile constituents were identified in L. japonica Thunb. from Guangxi Zhuang Autonomous Region, mainly including methyl linolenate, n-hexadecanoic acid and ζ-muurolene; 18 volatile constituents were identified in L. japonica Thunb. from Hunan Province, mainly including n-hexadecanoic acid, linoleic acid and α-curcumene. [Conclusion] Main volatile constituents in L. japonica Thunb. from two different origins varied significantly. 展开更多
关键词 Lonicera japonica Thunb. Volatile constituents GC-MS Different origins
下载PDF
Walnut Tree Grafting Experiments in Different Areas in Yunnan Province 被引量:1
2
作者 赵廷松 范志远 +8 位作者 谭凤琼 王洪艳 潘莉 邹伟烈 杜春花 刘娇 曾清贤 饶绍松 王斌 《Agricultural Science & Technology》 CAS 2017年第4期704-706,共3页
Yunnan has an area of 2.88 million hm2 walnut trees. Due to freezing in- jury and rapid growth, however, there are a lot of iron walnuts or inferior-quality walnuts ready for grafting. In five years, we conducted expe... Yunnan has an area of 2.88 million hm2 walnut trees. Due to freezing in- jury and rapid growth, however, there are a lot of iron walnuts or inferior-quality walnuts ready for grafting. In five years, we conducted experiments in Kunming (Yunnan Academy of Forestry), Gongshan County, Gucheng City, Luliang County, and Ludian County by cleft grafting, veneer grafting, bark grafting and whip grafting. The grafting approaches should be selected according to grafting requirements, characteristics, and survival rate. For example, with a low survival rate, cleft grafting can be abandoned, and the rest approaches might be chosen as per practical demands. 展开更多
关键词 YUNNAN Different areas Walnut trees Grafting experiment
下载PDF
Geological features and S isotope composition of tin deposit in Dachang ore district in Guangxi 被引量:6
3
作者 成永生 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第9期2938-2945,共8页
The geological investigation of the Dachang ore field was carried out in detail, and the geological characteristics of the deposits, consisting of the Tongkeng and Dafulou deposits, were observed and researched system... The geological investigation of the Dachang ore field was carried out in detail, and the geological characteristics of the deposits, consisting of the Tongkeng and Dafulou deposits, were observed and researched systematically. It suggests that the mineralization types of Changpo ore are composed of cracking vein, thin vein, bedded vein and thin vein-net vein disseminated types. The cracking vein ore is usually lens-shaped in the vertical direction. The thin vein ore is always characterized by a stable trend and tendency. The bedded ore always occurs along the strata in the way of filling and metasomatism in the fracture system. In terms of Bali-longtoushan ore, it is characterized by complicated mineral components and a variety of minerals. More generally, ore textures consist of the anhedral-subhedral shapes and thin particle, and secondary with the interstitial texture, solid solution separation texture, dissolution texture, corona texture, and crushing texture, yet ore structures include the massive, veinlet, disseminated, banded, miarolitic, biological residual and brecciated structure. In addition, the sulfur isotopes of the metal sulfide were analyzed. The results show that the δ34S values of Tongkeng ore range from-0.30% to 1.38% with more dispersed characteristics, yet in terms of Dafulou ore, the δ34S values are from-0.15% to 0.22% which are characterized by more focused. This indicates that the sulfur isotope composition has large difference between the different deposits. The sulfur isotope values of the Dafulou ore are concentrated relatively, yet are dispersed for the Tongkeng ore. Likewise, there are also divergences of sulfur isotopes for the different minerals. The sulfur isotope values of pyrrhotine are dispersed, yet are homogeneous for pyrite. In short, the divergence of the sulfur isotope is reflected in both the different deposits and minerals, all of these may account for the difference of sulfur sources. 展开更多
关键词 deposit geology sulfur isotope sulfur sources Dachang tin deposit
下载PDF
Wavy Distribution of Trace Elements in Phytolacca Samples from Different Areas 被引量:4
4
作者 杜莹 欧阳荔 +1 位作者 刘雅琼 王京宇 《Journal of Chinese Pharmaceutical Sciences》 CAS 2004年第4期271-275,共5页
To study the distribution of 25 elements, i.e. Be, Cd, Ce, Cr, Cu, Dy, Er,Eu, Gd, Ge, Ho, La, Lu, Mo, Nd, Pb, Pr, Sm, Sr, Tb, Tl, Tm, Y, Yb and Zn in Phytolacca, atraditional Chinese medicinal herb, collected from nin... To study the distribution of 25 elements, i.e. Be, Cd, Ce, Cr, Cu, Dy, Er,Eu, Gd, Ge, Ho, La, Lu, Mo, Nd, Pb, Pr, Sm, Sr, Tb, Tl, Tm, Y, Yb and Zn in Phytolacca, atraditional Chinese medicinal herb, collected from nine areas of P. R. China. Methods Twenty-fiveelements in Phytolacca including essential elements, toxic elements and rare earth elements intraditional Chinese medicinal herbs from different areas were analyzed by ICP-MS. Results The 25elements in Phytolacca were determined by ICP-MS under optimized conditions. The detection limitswere 0.003 -0.71 ng·mL^(-1). The recoveries were 88% - 118% . The relative standard deviations ofthe measurements were 1.7% - 13.3%. Conclusion The determined concentrations of elements inPhytolacca acinosa Roxb vary from one area to another; however, the distribution tendency ofelements in all the samples is similar. The distribution tendency of rare earth elements inPhytolacca acinosa Roxb is consistent with that in nature. 展开更多
关键词 traditional chinese medicinal herbs trace elements ICP-MS DISTRIBUTION
下载PDF
Effect of Different Soak Treatments on Breaking Seed Dormancy in Soil Seed Bank from Different Degraded Grasslands 被引量:6
5
作者 魏学红 格桑卓玛 《Agricultural Science & Technology》 CAS 2010年第8期173-175,共3页
[Objective] The aim was to study the effect of different soak treatments on breaking seed dormancy in soil seed bank from different degraded grasslands. [Method] Different concentrations of H2SO4,GA3 and KNO3 were use... [Objective] The aim was to study the effect of different soak treatments on breaking seed dormancy in soil seed bank from different degraded grasslands. [Method] Different concentrations of H2SO4,GA3 and KNO3 were used for soaking the seeds in the soil seed bank from different degraded grasslands,and the germination number of seeds was detected. [Result] When the seeds from soil seed bank were soaked with 60%,70%,80% and 90% H2SO4,the germination number of seeds was 0,indicating that the germination of seeds was inhibited; when the seeds were soaked with GA3,the germination number of seeds increased with the concentration of GA3 increasing. When the concentration of GA3 increased to 0.10%,the germination of seeds was inhibited; when the seeds were soaked with 0.2% KNO3,the germination number of seeds was greater than the blank control. [Conclusion] The number of remaining seeds was more in the soil seed banks collected from moderately degraded grassland and heavily degraded grassland; while the number of remaining seeds was small in the soil seed banks collected from lightly degraded grassland and extremely degraded grassland. 展开更多
关键词 Different degraded grasslands Soil seed bank Soak DORMANCY
下载PDF
HPLC Determination of Harpagoside and Cinnamic Acid in Radix Scrophulariae 被引量:5
6
作者 谢丽华 刘洪宇 +4 位作者 徐秉玖 王璇 王建华 徐风 蔡少青 《Journal of Chinese Pharmaceutical Sciences》 CAS 2001年第3期148-151,共4页
A gradient HPLC method was established for the determination of harpagoside and cinnamic acid in Radix Scrophulariae (Xuanshen) and a proposition was put forward for the lowest content of the characteristic and active... A gradient HPLC method was established for the determination of harpagoside and cinnamic acid in Radix Scrophulariae (Xuanshen) and a proposition was put forward for the lowest content of the characteristic and active constituent (harpagoside) for qualified Radix Scrophulariae. The experimental conditions were as follows: Ultrasphere ODS column (250 mm 4.6 mm, 5 mm), mobile phase: acetonitrile-water (containing 1.0% acetic acid) (20:8050:50) (20 min), flow-rate 1 mLmin-1, room temperature, detection wavelength 278 nm. Twenty-eight samples of Xuan-shen (Radix Scrophulariae) from different districts of China were analyzed and the contents of harpagoside and cinnamic acid in Xuan-shen were 0.041~0.244% and 0.012~0.068% respectively. The recoveries (RSD)% were 97.13(0.80)% for harpagoside and 99.38(0.51)% for cinnamic acid. The method is simple and accurate. It can be used for the quality control of Radix Scrophulariae. We propose that the content of harpagoside in qualified Radix Scrophularia should be no less than 0.05%. 展开更多
关键词 Scrophularia ningpoensis HARPAGOSIDE Cinnamic acid HPLC
下载PDF
Soil Physical and Chemical Properties of Five Subtropical Forests in Lingao of Hainan
7
作者 薛杨 宿少锋 +1 位作者 王小燕 林之盼 《Agricultural Science & Technology》 CAS 2017年第8期1459-1464,共6页
With 5 types of typical forests as research object, the physical and chemical properties of different types of forests were analyzed by sample plot investigation method. The results showed that: the soil total porosi... With 5 types of typical forests as research object, the physical and chemical properties of different types of forests were analyzed by sample plot investigation method. The results showed that: the soil total porosity was the highest in the Casuarina equisetifolia forest (46.168%), but the lowest in the Encalyptus robusta forest (39.46%). The soil capillary porosity was the highest in the Acacia mangium forest (22.57%), but the lowest in the secondary forest (18.95%). The soil water content was the highest in the C. equisetifolia forest, with a mean value of 27.85%, but the lowest in the secondary forest, with a mean value of 4.34%. The soil pH values were in the range of 4.81-6.59, the soils in the A. mangium forest, C. equisetifolia forest and E. robusta forest were strongly acidic (pH 4.5-5.5), and the soils in the secondary forest and C. nucifera forest were weakly acidic. The soils had organic matter contents in the range of 0.34-28.68 g/kg, and showed an order of A. mangium forest〉C. equisetifolia forest〉E. robusta forest〉secondary forest〉C. nucifera forest, with a decreasing trend with the soil depth increasing. The soil total N contents were in the range of 0.10-1.63 g/kg, the A. mangium forest showed the highest soil total N contents, while the C. nucifera forest exhibited the lowest soil total N contents; the soil total P contents were in the range of 0.21-1.74 g/kg, and the E. robusta forest had the highest soil total P contents; and the soil total K contents were in the range of 0.16-2.15 g/kg, and the A. mangium forest exhibited the highest soil total K contents. The soil available P contents were in the range of 0.98-132.46 mg/kg; and the secondary forests had the highest soil available P contents; and the soil rapidly available K contents were in the range of 3.03-27.35 mg/kg, and the C. nucifera forest exhibited the highest soil rapidly available K contents. The soil ammonium N contents were in the range of 1.38-5.15 mg/kg, and the nitrate N contents were in the range were in the range of 0.56 -3.51 mg/kg. The A. mangium forest showed the highest soil nitrate N contents (with a mean value of 2.29 mg/kg) and ammonium N contents (with a mean value of 3.93 mg/kg). For the same forest type, with the increase of soil depth, the nitrate nitrogen and ammonium nitrogen content also showed a decreasing trend. 展开更多
关键词 Lingao County Coastal platform Different forest types Soil physical and chemical properties COMPARISON
下载PDF
Influences of Surface Drip Irrigation on the Growth, Yield and Quality of Several New Species of Guitang Sugarcane
8
作者 许树宁 唐胜 +5 位作者 许卫安 陈引芝 李毅杰 谢金兰 丘立杭 王维赞 《Agricultural Science & Technology》 CAS 2015年第8期1828-1832,共5页
[Objective] This paper discussed the influences of surface drip irrigation on the growth, yield and quality of several new species of Guitang, in order to provide references for the promotion of new species and high-y... [Objective] This paper discussed the influences of surface drip irrigation on the growth, yield and quality of several new species of Guitang, in order to provide references for the promotion of new species and high-yield cultivation. [Method] One species is planted in each region, and there were two controls dripping technology or no-dripping technology in each region. [Results] The average yield of dripping-pro- cessed land was 115.91 t/hm2, which was 19.73 t/hm2 higher than the control. The maximum output was GT31, followed by GT34. The output of all Guitang new species was higher than the control ROC22. The average sucrose of dripped sug- arcane was 14.68%, which was 0.19% less than the control of 14.83%. The drip- ping technology was economically beneficial, rising by 15.2% compared with the control. The highest dripping efficiency was GT31, while the lowest one was ROC22. The increasing ratios of drip irrigation efficiency of the tested new Guitang species were higher than ROC22. [Conclusions] Under the drip irrigation condition, the sugarcane yield was extremely higher than the control of non-dripping irrigation, and the economic efficiency was significant. However, the sugar in the sugarcane declined slightly. The sensitivity of several new Guitang species to water was higher than the control ROC22. 展开更多
关键词 SUGARCANE Drip irrigation Different species Yield SUCROSE
下载PDF
Quantitative Analysis of Flavonoids in Scutellariae Radix of Different Sources and Seasonal Variation by HPLC 被引量:2
9
作者 张永煜 郭允珍 +6 位作者 上田博之 针谷羲弘 恩田政行 桥本和则 池谷幸信 罔田稔 丸野政雄 《Journal of Chinese Pharmaceutical Sciences》 CAS 1998年第3期26-29,共4页
The seasonal and source variations of flavonoid contents in Scutellariae Radix were investigated by using the materials collected at the same place in Liaoning Province, China, during three years, 1990~1992, and in s... The seasonal and source variations of flavonoid contents in Scutellariae Radix were investigated by using the materials collected at the same place in Liaoning Province, China, during three years, 1990~1992, and in seven other provinces in China. Four principal flavonoids in the plant roots, i.e., baicalin, baicalein, wogonin 7 O glucuronide and wogonin were analyzed by using a reversed phase chromatographic system with a chemically bonded ODS silica gel column and phosphate buffer methanol (68:32 and 1:1) as mobile phase. The contents of the four compounds combined in the herb collected at Chengde, Hebei Province are the highest. The results show that the best time for harvesting the roots in Liaoning Province is the end of August. 展开更多
关键词 Scutellariae Radix Scutellaria baicalensis Georgi Different sources Different harvest times
全文增补中
Comparison of roosting habitat characteristics of two sympatric pheasants during springtime at Dazhong Mountain,southwestern China 被引量:1
10
作者 李宁 周伟 +2 位作者 李伟 张庆 王学荣 《Chinese Birds》 2010年第2期132-140,共9页
Hume's Pheasant(Syrmaticus humiae) and the Silver Pheasant(Lophura nycthemera) are two sympatric bird species at Dazhong Mountain of Yunnan Province,southwestern China.We investigated characteristics of roosting h... Hume's Pheasant(Syrmaticus humiae) and the Silver Pheasant(Lophura nycthemera) are two sympatric bird species at Dazhong Mountain of Yunnan Province,southwestern China.We investigated characteristics of roosting habitats of the two pheasants from February to April,2004 in this area.Multiple statistics,Matryoshka and a habitat classification-tree were used to analyze the selection of roosting habitats of these pheasants. The results of the habitat classification-tree indicated that several separations occurred in their macro and micro roosting habitats in the study area. The two pheasants had similar crucial requirements for and selection of ecological roosting factors,which allow them to live in the same macrohabitat.Competition between these two pheasants was avoided by separation of spatial elements,such as roosting trees and topographic characteristics.For safety strategy,Hume's Pheasant adopted primarily a way of'uneasily found habitat cover plus easy escape',while the Silver Pheasant employed a unique way of'uneasily found habitat cover'.For tactics of keeping warm,Hume's Pheasant selected mainly a method of'suitable vegetation supplemented with suitable topography',while the Silver Pheasant chose a unique man-ner of'suitable vegetation'. 展开更多
关键词 Syrmaticus humiae Lophura nycthemera SYMPATRY roosting habitat selection
下载PDF
Analysis on the Origin and Phylogenetic Status of Tong Sheep Using 12 Blood Protein and Nonprotein Markers
11
作者 孙伟 常洪 +5 位作者 杨章平 耿荣庆 角田健司 任战军 陈宏宇 Musa H.Hussein 《Journal of Genetics and Genomics》 SCIE CAS CSCD 北大核心 2007年第12期1097-1105,共9页
This study is based on the Tong sheep obtained by the random sampling method of typical colonies in the central area of Baishui County in Shaanxi Province, China. An investigation was undertaken to clarify the gene co... This study is based on the Tong sheep obtained by the random sampling method of typical colonies in the central area of Baishui County in Shaanxi Province, China. An investigation was undertaken to clarify the gene constitution of blood protein and nonprotein types of Tong sheep. Twelve genetic markers were examined by starch-gel electrophoresis and cellulose acetate electrophoresis. Polymorphism in Tong sheep was found at the following 10 loci, transferrin (Tf), alkaline phosphatase (Alp), leucine aminopeptidase (Lap), arylesterase (Ary-Es), hemoglobin-β (Hb-β), X-protein (X-p), carbonic anhydrase (CA), catalase (Cat), malate dehydrogenase (MDH), and lysine (Ly), whereas, albumin (A1) and postalbumin (Po) loci were monomorphic. Genetic approach degree method and phylogenetic relationship clustering method were used to judge the origin and phylogenetic status of Tong sheep. Results from both methods maintained that Tong sheep belonged to the "Mongolia group", and Mongolia sheep was the origin of Tong sheep. This was also supported by the history of Tong sheep breeding. Compared to the phylogenetic relationship clustering method, the genetic approach degree method was more reliable for the extraction from East and South of Central Asia, and was more effective in reflecting the breeding course of Tong sheep. 展开更多
关键词 Tong sheep ORIGIN phylogenetic status genetic approach degree phylogenetic relationship clustering
下载PDF
Determination of Poliumoside and Forsythoside B in Different Parts of Callicarpa kwangtungensis and Its Plants from Different Habitats 被引量:1
12
作者 李开斌 孙刚 +2 位作者 马四补 晏晨 李春植 《Agricultural Science & Technology》 CAS 2016年第5期1080-1082,1088,共4页
[Objective] This study was conducted to determinate the contents of poliumoside and forsythoside B in Callicarpa kwangtungensis,so as to reveal the distribution of two index components(poliumoside and forsythoside B... [Objective] This study was conducted to determinate the contents of poliumoside and forsythoside B in Callicarpa kwangtungensis,so as to reveal the distribution of two index components(poliumoside and forsythoside B) in the plant and to compare the contents of these components in the medicinal materials from different habitats.[Methods] Comparison and analysis of the contents of the two target components in different parts(root,branch,leaf and fruit) of Callicarpa kwangtungensis from the same habitat and in Callicarpa kwangtungensis from different production areas were performed according to the pharmacopoeia standard.[Result]The highest content of poliumoside wasdetected in fruit,and the content of forsythoside B was the highest in the branch.The contents of the two kinds of components were in order of branch fruit leafroot;The contents of the components were four times higher than China pharmacopeia(0.5%) in Jian,Tonggu,Anyuan,and Ganzhou of Jiangxi Province and the fifth area,Taijiang County of Qiandongnan Miao and Dong Autonomous Prefecture(QMDAP),among which Ganzhou and Taijiang showed the highest contents.[Conclusion] The differences of poliumoside and forsythoside B were obvious in different habitats and different parts of Callicarpa kwangtungensis. 展开更多
关键词 Callicarpa kwangtungensis CONTENTS Different habitats Different parts
下载PDF
The Characteristics of Spatial Distribution of Saline-alkali Wasteland in Datong Basin, Northern China 被引量:3
13
作者 朱楚馨 毕如田 《Agricultural Science & Technology》 CAS 2015年第8期1803-1809,共7页
[Objective] Saline-alkali wasteland is a kind of land use type that formed by soil salinization and secondary salinization. To study the causes of spatial distri- bution of saline-alkali wasteland could be used as ref... [Objective] Saline-alkali wasteland is a kind of land use type that formed by soil salinization and secondary salinization. To study the causes of spatial distri- bution of saline-alkali wasteland could be used as reference for the amelioration and is significant for developing the reserved land with great potential. [Method] The re- search set a total of 1 729 sampling points in the study area of 34 433 hm2. Spa- tial analyses were used to find out the causes of saline-alkali wasteland in Datong basin from four factors: topography, geology, hydrology and soil. DEM and land use data were used to calculate distribution index of topography, and distribution of the total salinity (TS) and pH was analyzed by means of IDW interpolation. [Result] The results showed that saline-alkali wasteland was distributed on flat and low-lying ter- rains with poor drainage, which led to salt accumulation. 87% of saline-alkali wasteland was distributed on Quaternary Holocene alluvium whose performance of soil hydraulic conductivity was poor. TS value distribution was that in midstream re- gion was the highest, less in upstream region and the least in downstream region along the rivers, and TS value decreased when distance between saline-alkali wasteland and rivers increased. The major soil types in Datong basin were fluvo- aquic soil and saline soil. Both of the two soil types were of high TS value and pH value, and heavily salinized and strongly alkalized. [Conclusion] High groundwater table and the existence of two salt accumulation centers are the two causes of saline-alkali wasteland in Datong basin. The key to ameliorate saline-alkali waste- land is to descend the groundwater table and lessen salt accumulation. 展开更多
关键词 Datong basin saline-alkali wasteland spatial distribution
下载PDF
Connections on Phase Space of AutonomousMechanical Systems with Constraints
14
作者 郭永新 梅凤翔 《Journal of Beijing Institute of Technology》 EI CAS 1997年第3期213-220,共8页
The covariance of a dynamical flow with respect of a connection on tangent burdle is put forward The connection of an autonomous constrained mechanical system is found whose geodesic equations are equations of... The covariance of a dynamical flow with respect of a connection on tangent burdle is put forward The connection of an autonomous constrained mechanical system is found whose geodesic equations are equations of motion of the systems The connection is determined by dynamical functions and constraints of the system of the system and is reduced to the usual dynarmical connection of the dynamical flow is second drder homogmogeneous one. 展开更多
关键词 vertical endomorphism coection dynamical flow GEODESIC
下载PDF
Analysis on Influential Factors of Peasants' Willingness to Exit Homestead in Regions with Different Economy Development Levels——Taihe Village,Chaohu County-Level City,and Ancang Village,Taihu County as Examples 被引量:1
15
作者 刘逦 杨子生 杨青 《Agricultural Science & Technology》 CAS 2016年第5期1268-1270,共3页
The research concluded peasants' willingness on homestead exiting and influential factors by questionnaire survey and interviewing in two villages with varied levels of economic development in Anhui Province.Comparis... The research concluded peasants' willingness on homestead exiting and influential factors by questionnaire survey and interviewing in two villages with varied levels of economic development in Anhui Province.Comparisons were performed on subjective factors and objective factors were explored by Logistic regression.The results showed that both of education background and homestead use have positive correlation with peasants' willingness on homestead exit;the number of family members has negative effects on peasants in advanced village but the number of migrant workers or members living in cities has positive effects;the area of homestead has positive effects on peasants in underdeveloped village.Therefore,the emphasis should be varied on homestead exit upon village economy and it is necessary to reinforce homestead exit promotion at improving immigrants' reception work,social security,employment,and education. 展开更多
关键词 Homestead exit Different economic development levels Peasants' willingness Influential factors
下载PDF
Dynamics Characteristics and Topographic Profile Shaping Process of Feiyan Shoal at the Yellow River Delta 被引量:1
16
作者 应铭 李九发 +1 位作者 陈沈良 戴志军 《Marine Science Bulletin》 CAS 2008年第2期74-88,共15页
Feiyan Shoal is a sub Yellow River Delta, which was formed from Jan. 1964 to May 1976, when the Yellow River entered sea via Diaokou Channel. Since the terminal reach shifted to Qingshuigou channel in 1976, Feiyan Sho... Feiyan Shoal is a sub Yellow River Delta, which was formed from Jan. 1964 to May 1976, when the Yellow River entered sea via Diaokou Channel. Since the terminal reach shifted to Qingshuigou channel in 1976, Feiyan Shoal has been experiencing severe erosion and retreat. This paper explains the evolutionary characteristics of the typical profile of Feiyan Shoal from the perspective of dynamical force and sediments' characteristics. All this is on the basis of the data of topographic profiles observed since the 1970s and the samples of hydrology and sediments collected in situ in Apr. 2004, the analysis of the retreating distance, and the tidal and wave friction velocity distribution. Feiyan Shoal topographical profile has experienced a course of "fast erosion and retrogression - slow eroding modulation - fluctuate triggering change" in recent 30 years, which is also the gradual disappearing process of the delta front. The different intensity of sediment erosion resistance is the main reason for the erosion speed changes. Due to the hydrodynamic force changes, the water depth range of maximum retreating distance and between erosion and progradation became shallow. It indicates that the storm tide will still be the triggering force of seashore topographic profile evolutions in the future. 展开更多
关键词 The Yellow River Delta Feiyan Shoal EROSION wave and tidal co-action topographic profile sediment transport
下载PDF
Application of Stable Isotope Tracing Technologies in Identification of Transformation among Waters in Sanjiang Plain,Northeast China 被引量:6
17
作者 XU Yingying YAN Baixing +2 位作者 LUAN Zhaoqing ZHU Hui WANG Lixia 《Chinese Geographical Science》 SCIE CSCD 2013年第4期435-444,共10页
In order to investigate the transformation among the precipitation,groundwater,and surface water in the Sanjiang Plain,Northeast China,precipitation and groundwater samples which were collected at the meteorological s... In order to investigate the transformation among the precipitation,groundwater,and surface water in the Sanjiang Plain,Northeast China,precipitation and groundwater samples which were collected at the meteorological station of the Sanjiang Mire Wetland Experimental Station,Chinese Academy of Sciences and the surface water which collected from the Wolulan River were used to identify the transformation of three types of water.The isotope composition of different kinds of water sources were analyzed via stable isotope(deuterium and oxygen-18) investigation of natural water.The results show a clear seasonal difference in the stable isotopes in precipitation.During the cold half-year,the mean stable isotope in precipitation in the Sanjiang Plain reaches its minimum with the minimum temperature.The δ18O and δD values are high in the rainy season.In the Wolulan River,the evaporation is the highest in August and September.The volume of evaporation and the replenishment to the river is mostly same.The groundwater is recharged more by the direct infiltration of precipitation than by the river flow.The results of this study indicate that the water bodies in the Sanjiang Plain have close hydrologic relationships,and that the transformation among each water system frequently occurs. 展开更多
关键词 hydrogen and oxygen stable isotopes GROUNDWATER PRECIPITATION water cycle RECHARGE
下载PDF
Analysis of the distribution characteristics of ^(226)Ra and ^(228)Ra and their sources in the western part of Qinghai Lake 被引量:3
18
作者 孔凡翠 沙占江 +5 位作者 杜金洲 苏维刚 于晨光 赵顺利 胡菊芳 冶梅 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2015年第6期1402-1412,共11页
The ^226Ra and ^228Ra activities of Qinghai Lake surface water, groundwater, river water, suspended particles, and bottom sediments were measured in a gamma-ray spectrometer. The sources of ^226Ra and ^228Ra were disc... The ^226Ra and ^228Ra activities of Qinghai Lake surface water, groundwater, river water, suspended particles, and bottom sediments were measured in a gamma-ray spectrometer. The sources of ^226Ra and ^228Ra were discussed according to their distribution characteristics. ^226Ra and ^228Ra activities (dpm/(100 L)) ranged from 14.13±0.22 to 19.22±0.42 and 17.724-0.66 to 30.96:kl.47 in the surface water of the North Bay, respectively, and from 7.88±0.24 to 33.80±0.47 and 15.73±0.74 to 57.31±1.44, respectively, in the South Bay. The surface water near the estuary had a lower salinity and had a higher concentration of radium isotopes than the samples collected further away. The farther offshore the sample, the higher the salinity was, and the lower the radium isotope activity. The distribution of radium activities in the western part of Qinghai Lake is controlled by several factors, including Buha River runoff, desorption from suspended particles derived from the river, groundwater discharge, and a small amount of diffusion from the sediment. 展开更多
关键词 ^226RA ^228Ra surface water of Qinghai lake groundwater river water Qinghai Lake
下载PDF
Phase velocity in 2D TTI media 被引量:6
19
作者 Xuan Yihua He Qiaodeng Lin Yan 《Applied Geophysics》 SCIE CSCD 2007年第1期25-28,共4页
We derive an expression for phase velocity in 2D tilted transverse isotropy (TTI) media. Snapshots of phase velocity in TTI and transverse isotropy (TI) model media are simulated and analyzed using the derived exp... We derive an expression for phase velocity in 2D tilted transverse isotropy (TTI) media. Snapshots of phase velocity in TTI and transverse isotropy (TI) model media are simulated and analyzed using the derived expression. In addition, the x-component character differences between the modeled phase velocities of the two media models are compared and analyzed. 展开更多
关键词 tilted transverse isotropy TTI media transverse isotropy TI media phase velocity.
下载PDF
Influence of assimilating ground-based microwave radiometer data into the WRF model on precipitation 被引量:3
20
作者 HE Wenying CHEN Hongbin LI Jun 《Atmospheric and Oceanic Science Letters》 CSCD 2020年第2期107-112,共6页
Ground-based microwave radiometers profilers(MWRPs)have been used in numerical weather prediction(NWP)systems and show different impacts on forecasts.Currently,there are around hundreds of ground-based MWPRs used in w... Ground-based microwave radiometers profilers(MWRPs)have been used in numerical weather prediction(NWP)systems and show different impacts on forecasts.Currently,there are around hundreds of ground-based MWPRs used in weather stations over China;however,the application of MWPRs in NWP systems is rather limited.In this work,two MWRP retrieved profiles were assimilated into the Weather Research and Forecasting(WRF)model for a rainstorm event that occurred in Beijing,China.The quality of temperature and humidity profiles retrieved from the MWRP was evaluated against radiosonde observations and showed the reliability of the two MWRP products.Then,comparisons between the measurements of ground-based rain gauges and the corresponding forecasted precipitation in different periods of the rainstorm were investigated.The results showed that assimilating the two MWRPs affected the distribution and intensity of rainfall,especially in the early stage of the rainstorm.With the development of the rainstorm,adding MWRP data showed only a slight influence on the precipitation during the stable and mature period of the rainstorm,since the two MWRP observations were too limited to affect the large area of heavy rainfall. 展开更多
关键词 Microwave radiometer ground-based observation ASSIMILATION PRECIPITATION
下载PDF
上一页 1 2 11 下一页 到第
使用帮助 返回顶部