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厦门马銮湾有机污染、富营养化状况下的生化关系 被引量:34
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作者 暨卫东 《海洋学报》 CAS CSCD 北大核心 1998年第1期134-143,共10页
厦门马銮湾有机污染、富营养化状况下的生化关系暨卫东(国家海洋局第三海洋研究所,厦门361005)关键词有机污染,富营养化,生化关系1引言马銮湾养殖海域位于厦门西港的西侧,与厦门西港仅一堤之隔,属于封闭式的养殖海域.马... 厦门马銮湾有机污染、富营养化状况下的生化关系暨卫东(国家海洋局第三海洋研究所,厦门361005)关键词有机污染,富营养化,生化关系1引言马銮湾养殖海域位于厦门西港的西侧,与厦门西港仅一堤之隔,属于封闭式的养殖海域.马銮湾内有260hm2余虾池和130... 展开更多
关键词 海洋污染 富营养化 生化关系 厦门 马銮湾
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病毒性肝炎及原发性肝癌AFP等的生化改变关系分析 被引量:3
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作者 张勇华 李强强 赵建敏 《当代医学》 2016年第13期43-44,共2页
目的分析病毒性肝炎及原发性肝癌AFP等的生化改变关系。方法将62例病毒性肝炎患者以及62例原发性肝癌患者研究对象,采用微粒子酶免包被法对研究中所有患者进行AFP检测,对检测结果进行回顾性分析,观察生化改变关系。结果 AFP>25 ng/m ... 目的分析病毒性肝炎及原发性肝癌AFP等的生化改变关系。方法将62例病毒性肝炎患者以及62例原发性肝癌患者研究对象,采用微粒子酶免包被法对研究中所有患者进行AFP检测,对检测结果进行回顾性分析,观察生化改变关系。结果 AFP>25 ng/m L肝癌患者TB明显低于病毒性肝炎患者,同时ALT、TBA低于急性肝炎以及慢性肝炎患者,而GGT则明显高于病毒性肝炎患者,组间比较差异具有统计学意义(P<0.05)。结论患者AFP若是连续3个月均在350 ng/m L以上、GGT在350μ/L以上,但ALT并无明显增高时,应当怀疑是否为癌性AFP,此时需要对患者进行进一步的CT检查以及B超检查,对患者的肝癌进行诊断。 展开更多
关键词 病毒性肝炎 原发性肝癌 生化关系
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凋落物和土壤浸提液对油松种子萌发与幼苗生长的影响 被引量:15
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作者 雷日平 陈辉 刘建军 《中南林学院学报》 CSCD 2001年第1期82-84,共3页
混交林的生态和经济效益越来越引起人们的关注 ,为了探讨混交林中各树种的生化关系 ,研究了分布于陕西省宁陕县火地塘林场的华山松 (Prunus armandii)和锐齿栎 (Quercus acutissima)林下土壤及凋落物浸提液对油松 (Prunus tabulaeformis... 混交林的生态和经济效益越来越引起人们的关注 ,为了探讨混交林中各树种的生化关系 ,研究了分布于陕西省宁陕县火地塘林场的华山松 (Prunus armandii)和锐齿栎 (Quercus acutissima)林下土壤及凋落物浸提液对油松 (Prunus tabulaeformis)种子发芽、胚根和幼茎生长的影响 .结果表明 :各个浓度水平的两种森林林下土壤浸提液对种子发芽 ,幼茎生长和胚根生长都无显著影响 ;各个浓度水平的凋落物浸提液对胚根和幼茎生长有显著影响 ,经α=0 .0 5水平检验 ,1∶ 10液对胚根生长有显著的促进作用 ,原液和 1∶ 2 0液无显著影响 ,1∶ 10液和 1∶ 2 0液对幼茎生长有显著的促进作用 。 展开更多
关键词 华山松 锐齿栎 油松 凋落物浸提液 土壤浸提液 种子萌发 幼苗生长 生化关系 他感作用
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Divergent growth trends and climatic response of Picea obovata along elevational gradient in Western Sayan mountains, Siberia 被引量:1
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作者 Elena BABUSHKINA Liliana BELOKOPYTOVA +2 位作者 Dina ZHIRNOVA Anna BARABANTSOVA Eugene VAGANOV 《Journal of Mountain Science》 SCIE CSCD 2018年第11期2378-2397,共20页
In mountain ecosystems,plants are sensitive to climate changes,and an entire range of species distribution can be observed in a small area.Therefore,mountains are of great interest for climate–growth relationship ana... In mountain ecosystems,plants are sensitive to climate changes,and an entire range of species distribution can be observed in a small area.Therefore,mountains are of great interest for climate–growth relationship analysis.In this study,the Siberian spruce’s(Picea obovata Ledeb.)radial growth and its climatic response were investigated in the Western Sayan Mountains,near the SayanoShushenskoe Reservoir.Sampling was performed at three sites along an elevational gradient:at the lower border of the species range,in the middle,and at the treeline.Divergence of growth trends between individual trees was observed at each site,with microsite landscape-soil conditions as the most probable driver of this phenomenon.Cluster analysis of individual tree-ring width series based on inter-serial correlation was carried out,resulting in two sub-set chronologies being developed for each site.These chronologies appear to have substantial differences in their climatic responses,mainly during the cold season.This response was not constant due to regional climatic change and the local influence of the nearby Sayano-Shushenskoe Reservoir.The main response of spruce to growing season conditions has a typical elevational pattern expected in mountains:impact of temperature shifts with elevation from positive to negative,and impact of precipitation shifts in the opposite direction.Chronologies of trees,growing under more severe micro-conditions,are very sensitive to temperature during September–April and to precipitation during October–December,and they record both inter-annual and long-term climatic variation.Consequently,it would be interesting to test if they indicate the Siberian High anticyclone,which is the main driver of these climatic factors. 展开更多
关键词 Climate change Tree-ring width Growth trends Climate-growth relationship Picea obovata Elevational gradient
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Intra-specific genetic relationship analyses of Elaeagnus angustifolia based on RP-HPLC biochemical markers 被引量:1
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作者 WANG Qiang RUAN Xiao +2 位作者 HUANG Jun-hua XU Ning-yi YAN Qi-chuan 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE CAS CSCD 2006年第4期272-278,共7页
Elaeagnus angustifolia Linn. has various ecological, medicinal and economical uses. An approach was established using RP-HPLC (reversed-phase high-performance liquid chromatography) to classify and analyse the intra... Elaeagnus angustifolia Linn. has various ecological, medicinal and economical uses. An approach was established using RP-HPLC (reversed-phase high-performance liquid chromatography) to classify and analyse the intra-specific genetic relationships of seventeen populations of E. angustifolia, collected from the Xinjiang areas of China. Chromatograms of alcohol-soluble proteins produced by seventeen populations of E. angustifolia, were compared. Each chromatogram of alcohol-soluble proteins came from a single seed of one wild plant only. The results showed that when using a Waters Delta Pak. C 18, 5μm particle size reversed phase column (150 mm×3.9mm), a linear gradient of 25%-60% solvent B with flow rate of 1 ml/min and run time of 67 min, the chromatography yielded optimum separation of E. angustifolia alcohol-soluble proteins. Representative peaks in each population were chosen according to peak area and occurrence in every seed. The converted data on the elution peaks of each population were different and could be used to represent those populations. GSC (genetic similarity coefficients) of 41% to 62% showed a medium degree of genetic diversity among the populations in these eco-areas. Cluster analysis showed that the seventeen populations orE. angustifolia could be divided into six clusters at the GSC=0.535 level and indicated the general and unique biochemical markers of these clusters. We suggest that E. angustifolia distribution in these eco-areas could be classified into six variable species. RP-HPLC was shown to be a rapid, repeatable and reliable method for E. angustifolia classification and identification and for analysis of genetic diversity. 展开更多
关键词 Elangustifolia Intra-specific genetic relationship Genetic diversity Biochemical marker
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ANALYSIS OF EVOLUTIONARY RELATIONSHIP BETWEEN ASTASIA LONGA AND EUGLENA GRACILIS BY USING RAPD TECHNIQUE AND CLADISTIC ANALYSIS 被引量:1
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作者 王江新 施之新 +1 位作者 甘小妮 谢树莲 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2001年第1期40-50,共11页
Although both Astasia longa and Euglena gracilis belong to different genera, they share many morphological characters except that A. longa has no chloroplast. In the 1940’s, on the basis of the finding that in darkne... Although both Astasia longa and Euglena gracilis belong to different genera, they share many morphological characters except that A. longa has no chloroplast. In the 1940’s, on the basis of the finding that in darkness or upon addition of some chemicals, E. gracilis would fade reversibly or irreversibly, some scholars hypothesised that A. longa evolved from E. gracilis by losing chloroplast. The authors’ use of RAPD and cladistic analyses in a study on the evolutionary relationship between A .longa and E. gracilis showed that the A. longa ’s relationship with E. gracilis was closer than that with other green euglenoids. This proves the hypothesis that A. longa evolved from E. gracilis is reasonable. The results of this study suggest that saprophytic colorless euglenoids were transformed from green euglenoids by losing their choroplasts. 展开更多
关键词 A. longa Euglena gracilis cladistic analysis molecular evolution RAPD
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Climate-growth relationship stability of Picea crassifolia on an elevation gradient,Qilian Mountain,Northwest China 被引量:2
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作者 LEI Jing-pin FENG Xiao-hui +2 位作者 SHI Zheng BAI Deng-zhong XIAO Wen-fa 《Journal of Mountain Science》 SCIE CSCD 2016年第4期734-743,共10页
Climate affects Picea crassifolia growth and climate change will lead to changes in the climate–growth relationship(i.e., the "divergence" phenomenon). However, standardization methods can also change the u... Climate affects Picea crassifolia growth and climate change will lead to changes in the climate–growth relationship(i.e., the "divergence" phenomenon). However, standardization methods can also change the understanding of such a relationship. We tested the stability of this relationship by considering several variables: 1) two periods(1952–1980 and 1981–2009), 2) three elevations(2700, 3000, and 3300 m), and 3) chronologies detrended using cubic splines with two different flexibilities. With increasing elevation, the climatic factor limiting the radial growth of Picea crassifolia shifted from precipitation to temperature. At the elevation of 2700 m, the relationship between radial growth and mean temperature of the previous December changed so that the more flexible spline had a greater precipitation signal. At the elevation of 3000 m, positive correlation of radial growth with mean temperature and precipitation in September of the previous year became more significant. At the elevation of 3300 m, positive correlation between radial growth and precipitation of the currentsummer and the previous spring and autumn was no longer significant, whereas the positive correlation between radial growth and temperature of the current spring and summer strengthened. The detrending with the most flexible spline enhanced the precipitation signal at 2700 m, while that with the least flexible spline enhanced the temperature signal at 3300 m. All results indicated that the divergence phenomenon was affected by the climatic signals in the chronologies and that it was most dependent on the detrending method. This suggests it is necessary to select a suitable spline bootstrap for studies of growth divergence phenomena. 展开更多
关键词 Climate change Detrending method Divergence problem Tree ring
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Educating Children in the Family Created in the Second Marriage in Today's Lithuania
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作者 Kestutis Ralys 《Sociology Study》 2014年第4期291-297,共7页
Since the end of the twenty-first century, relationships in the family have been rapidly changing in Lithuania. The changes correspond to changes in the birth-rate. The former model of birth-rate which was characteriz... Since the end of the twenty-first century, relationships in the family have been rapidly changing in Lithuania. The changes correspond to changes in the birth-rate. The former model of birth-rate which was characterized by the prevalence of legitimate children, child-bearing at a younger age and which ensured a change of generations, it was replaced by a new model characterized by having illegitimate children, the postponement of child-bearing, and low birth-rate, which does not ensure a change of generations. Although love relationships, marriage, and children are still considered to be the recognized values, these changes have affected the conception of child's education in the family and the perception of child as a value. It is therefore relevant to evaluate future spouses' preparation for a modern marriage and to constantly improve it. Such preparation is usually understood as young people's readiness far their first marriage. Readiness for the second marriage and child's education in the second family are no less important though still insufficiently explored empirically and theoretically generalized. This paper explores attitudes to child's education in the second marriage. The research was conducted inquiring people who wanted to create a family or establish long-term relationships. They were members of the online dating site "Harmonious Couple". 展开更多
关键词 Modern family REMARRIAGE attitudes to children's education a choice of a potential partner in children's education
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Urban Transformation and Nostalgia in Merdivenkoy, Istanbul
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作者 Emine Zeynep Güler 《History Research》 2013年第1期13-22,共10页
In this paper the author will try to discuss the experiences and narratives of three different categories of families living in Merdivenkoy, Fikirtepe, the oldest settlement and suburban area of the Anatolian side of ... In this paper the author will try to discuss the experiences and narratives of three different categories of families living in Merdivenkoy, Fikirtepe, the oldest settlement and suburban area of the Anatolian side of Istanbul, on the backdrop of urban transformation that will change the area soon. In life story narratives, these three examples give us information about the history, economic linkage, and life styles of neighboring families. The first category basically consists of the families that live in the area for a very long time, over some decades or more. Even one of them mentioned that, their family is living there for hundreds of years. The second category, which represents the biggest group living in the area, consists of families migrated from Sivas, a central Anatolian city, in the 1950s. Third category consist of Kurds migrated from eastern Anatolian villages and cities such as Mardin. Each category has different kinds of nostalgia about the past. Interviewees from the first category talk about family narratives related to the small village Merdivenk6y, Fikirtepe and the area. Mostly, they have a story of a "well off" family, structured and detailed narratives about the family history, including relations with the Ottoman Palace such as doing some sort of production for it. They seem very sensitive about the local cultural characteristics and what's going on in the area; realistic about and reconciled with what will happen as a result of slum clearance. Interviewees from the second category mostly emphasize the hardship of settling in a muddy suburban area, where once "muddy lands" now turned out to become valuable urban properties on which new and modem neighborhoods, shopping malls and office buildings will be built. They are expecting to get maximum gain out of the exchange of their small property, since they are desperately in need, because of the financial crisis situation. Although their houses with small gardens near the small industrial area are small, old, and neglected for years, they expect the most. Relatively newcomers, Kurdish people in the area talk about the good old days on the one hand and the painful stories about migration and settling on the other hand. They do not think about going back to their native lands, since here it is easier for them to find jobs in the informal economy as they live very close to central parts of the city. As a part of a larger research study focused on the experience of urban transformation, we made more than 50 interviews, trying to make a general outlook of the area, working on the dynamics of change before and after the urban transformation that had been started in June 2010. By using oral history research techniques and social science methodology, we conducted in-depth interviews with the people living in the neighborhood, made observations in the neighborhood and took photographs. The author's work is about the reflections of nostalgia in their family histories and experiences of different categories of families living in the area referring life story narratives. As far as the author can see in each group he works on, there are different contradictions related to their position in the city and conception of the area. The urban transformation presented and is perceived as a fortune for all of them, but it will have contradictory outcomes in reality for each as indicated in other examples in the world. 展开更多
关键词 family history urban renewal DISPLACEMENT Fikirtepe Istanbul
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To resolve recent natural immune defense effects of antimicrobial peptides in the gastrointestinal tract
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作者 Aili Wang 《International Journal of Technology Management》 2014年第4期45-47,共3页
The human gut is the normal habitat of a lot of microorganisms; in the long process of evolution they have developed a symbiotic relationship with the host. Under normal circumstances they do not damage the health, wh... The human gut is the normal habitat of a lot of microorganisms; in the long process of evolution they have developed a symbiotic relationship with the host. Under normal circumstances they do not damage the health, which totally owes to the barrier functions of the integral intestinal mucosa. Intestinal lnucosal barriers are mainly composed of four parts: mechanical barrier, immune barrier, chemical and biological barrier. Each of these functions has corresponding structural basis, an important barrier to prevent harmful substances and pathogens in the gut into the inner environment of the body, and to maintain a stable internal environment. 展开更多
关键词 Gastrointestinal tract antimicrobial peptides natural immunity immune defense
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Payment for Ecosystem Services Markets and Rural Development in BrazilmA Co-evolutionary Approach
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作者 Shigeo Shiki Simone de Faria Narciso Shiki +1 位作者 Patricia Lopes Rosado Elaine Aparecida Fernandes 《Journal of Environmental Science and Engineering(B)》 2013年第5期276-288,共13页
The article discusses the payment for ecosystem or environmental services markets in Brazil with a critical review, based on the ecological economics literature and focused on the concept of co-evolution. It is argued... The article discusses the payment for ecosystem or environmental services markets in Brazil with a critical review, based on the ecological economics literature and focused on the concept of co-evolution. It is argued that the mainstream approach which considers ecosystem services as an externality has many shortcomings and fails to consider institutional and political aspects---all very critical for the design and implementation of a PES (Payment for ecosystem services) project or program. The complexity and the diversity of co-evolutionary relations between ecosystem services and socioeconomic activities are spatially or territorially specific. In this sense, different types of PES market have to adapt and coevolve with different ongoing development processes. 展开更多
关键词 Payment for ecosystem services co-evolutionary approach rural development.
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Analysis of certain differential equation models in the economic system
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作者 Xingcong Mao 《International Journal of Technology Management》 2013年第4期86-88,共3页
The basic contradiction of socialist society is still a contradiction between the relations of production and productivity, the superstructure and the economic base. This contradiction is concentrated in the productio... The basic contradiction of socialist society is still a contradiction between the relations of production and productivity, the superstructure and the economic base. This contradiction is concentrated in the production relations and a series of interconnected links and aspects in the superstructure that don't match the development of the productivity, these links and they are concentrated in the economic system. Therefore, reforming the economic system is to reform the production relations and a series of interconnected links and aspects in the superstructure that don't match the development of the productivity under the premise of adhering to the basic system of socialism. This re^brm is a self-improvement and development of the socialist system in order to promote the development of the socialist productive forces and the development of socialist modernization greatly. 展开更多
关键词 equation models economic system reform.
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Flipping the College English Classroom
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作者 YUAN Jing-jing 《Sino-US English Teaching》 2015年第11期816-821,共6页
The flipped classroom is an emerging teaching mode which is originated from the United States and is now prevalent in many countries. It is helpful to build a more harmonious relationship between the teachers and the ... The flipped classroom is an emerging teaching mode which is originated from the United States and is now prevalent in many countries. It is helpful to build a more harmonious relationship between the teachers and the students, to enhance the students' self-study ability, to create a favorable learning environment, to realize the individualized teaching in class, and to improve the students' English ability. The study focuses on the college English classroom in China. The author tries to prove that the flipped classroom is a helpful way to improve the teaching and learning effect of college English classroom. A teaching procedure for the flipped college English classroom is designed in the hope of changing the current college English teaching condition. 展开更多
关键词 the flipped classroom college English activities design
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Frequency Variations of Power System Due to Switching of Renewable Energy Sources
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作者 Wendy L. Fuchs Ewald F. Fuehs 《Journal of Energy and Power Engineering》 2013年第1期1-9,共9页
Power systems in Germany mainly containing intermittently operating renewable sources require load/frequency control which is performed up to now at the AC transmissioh and distribution levels. Frequency control can b... Power systems in Germany mainly containing intermittently operating renewable sources require load/frequency control which is performed up to now at the AC transmissioh and distribution levels. Frequency control can be achieved by employing short-and long-term storage plants buffering and complementing renewable energy sources. A representative grid consists of a natural-gas-fired plant serving as frequency leader, long-term storage plant, wind-power farm with associated short-term storage plantfor energy buffering, and photovoltaic farm with associated short-term storage plant interconnected by a long transmission line to two load circuits. Transient analysis is performed with Mathemafica solving the differential equation system for frequency variation. Powerflow through the AC transmission line is limited by its impedance. The long transmission line must be segmented to achieve stability and voltage control over an 800 km distance. The renewable plants must be operated together with the storage plants in order tominimize frequency variations by smoothing the power output of renewable plants, achieving step-wise control of the transmission-line power. Although to date only AC Iransmission lines in Germany exist, it is anticipated that within the next 10 years these will beaugmented by DC high-voltage lines. 展开更多
关键词 Renewable sources frequency variations stability selection of transmission line.
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Drought effects on the plasticity in vessel traits of two endemic Magnolia species in the tropical montane cloud forests of eastern Mexico 被引量:1
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作者 Ernesto Chanes Rodríguez-Ramírez José Antonio Vázquez-García +2 位作者 Ignacio García-González Othón Alcántara-Ayala Isolda Luna-Vega 《Journal of Plant Ecology》 SCIE CSCD 2020年第3期331-340,共10页
Aims We aimed to evaluate how climatic fluctuations influence the plasticity of anatomical vessel traits and the width of annual tree-rings of two relict-endemic Mexican Magnolia species.Notwithstanding,few studies ha... Aims We aimed to evaluate how climatic fluctuations influence the plasticity of anatomical vessel traits and the width of annual tree-rings of two relict-endemic Mexican Magnolia species.Notwithstanding,few studies have assessed the drought effect on vessel traits in tropical montane cloud trees of eastern Mexico.Methods Through digital images of growth rings,we assessed the tree radial growth rate,age of the trees and plasticity in vessel traits regarding climatic fluctuations of the Mexican Magnolia species studied.We compared vessel density,hydraulic diameter and percentage of conductive area in drought years(DY)and non-drought years(NDY)in two Mexican Magnolia species.Important Findings For the first time,the plasticity that occurs in porous wood vessel traits to long-term climatic fluctuations was analysed for two endangered Magnolia species(Magnolia vovidesii and M.schiedeana)from two tropical montane cloud forests in Mexico.We found that temperature and precipitation were strongly associated with differences in tree-ring width when DY and NDY were compared.Our analyses revealed that a high plasticity in vessel anatomy of diffuse-porous wood was related to temperature and/or water availability for both Magnolia species studied.We concluded that anatomical adaptations to DY resulted in a substantial reduction in vessel traits when compared with NDY,and that the plastic adaptations played an essential role in water transport and safety for the survival of the studied species during stressful long periods. 展开更多
关键词 ADAPTABILITY climate variability drought–growth relationship Magnolia schiedeana Magnolia vovidesii quantitative wood anatomy
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Discovery of differential sequences for improving breeding and yield of cultivated Ophiocordyceps sinensis through ITS sequencing and phylogenetic analysis 被引量:4
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作者 CHENG Qi-Qing CHENG Chun-Song +6 位作者 OUYANG Yue LAO Chi-Chou CUI Hao XIAN Yu JIANG Zhi-Hong LI Wen-Jia ZHOU Hua 《Chinese Journal of Natural Medicines》 SCIE CAS CSCD 2018年第10期749-755,共7页
To accelerate the breeding process of cultivated Ophiocordyceps sinensis and increase its yield,it is important to identify molecular fingerprint of dominant O.sinensis.In the present study,we collected 3 batches of i... To accelerate the breeding process of cultivated Ophiocordyceps sinensis and increase its yield,it is important to identify molecular fingerprint of dominant O.sinensis.In the present study,we collected 3 batches of industrially cultivated O.sinensis product with higher yield than the others and compared their internal transcribed spacer(ITS)sequences with the wild and the reported.The ITS sequence was obtained by bidirectional sequencing and analyzed with molecular systematics as a DNA barcode for rapid and accurate identification of wild and cultivated O.sinensis collected.The ITS sequences of O.sinensis with detailed collection loci on NCBI were downloaded to construct a phylogenetic tree together with the sequences obtained from the present study by using neighbor-joining method based on their evolution relationship.The information on collection loci was analyzed with ArcGIS 10.2 to demonstrate the geographic distribution of these samples and thus to determine the origin of the dominant samples.The results showed that all wild and cultivated samples were identified as O.sinensis and all sequences were divided into seven phylogenetic groups in the tree.Those groups were precisely distributed on the map and the process of their system evolution was clearly presented.The three cultivated samples were clustered into two dominant groups,showing the correlation between the industrially cultivated samples and the dominant wild samples,which can provide references for its optimized breeding in the future. 展开更多
关键词 Ophiocordyceps sinensis ITS Phylogenetic relationship Artificial cultivation Evolution process
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Are regional precipitation-productivity relationships robust to decadal-scale dry period?
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作者 Zhongmin Hu Minqi Liang +2 位作者 Alan Knapp Jianyang Xia Wenping Yuan 《Journal of Plant Ecology》 SCIE CSCD 2022年第4期711-720,共10页
Precipitation(PPT)is the primary climatic determinant of plant growth and aboveground net primary productivity(ANPP)for many of the world’s major terrestrial ecosystems.Thus,relationships between PPT and productivity... Precipitation(PPT)is the primary climatic determinant of plant growth and aboveground net primary productivity(ANPP)for many of the world’s major terrestrial ecosystems.Thus,relationships between PPT and productivity can provide insight into how changes in climate may alter ecosystem functions globally.Spatial PPT–ANPP relationships for grasslands are found remarkably similar around the world,but whether and how they change during periods of extended climatic anomalies remain unknown.Here,we quantifed how regional-scale PPTANPP relationships vary between an extended wet and a dry period by taking advantage of a 35-year record of PPT and NDVI(as a surrogate for ANPP)at 1700 sites in the temperate grasslands of northern China.We found a sharp decrease in the strength of the spatial PPT–ANPP relationship during an 11-year period of below average PPT.We attributed the collapse of this relationship to asynchrony in the responses of different grassland types to this decadal period of increased aridity.Our results challenge the robustness of regional PPT–productivity if aridity in grasslands is increased globally by climate change. 展开更多
关键词 GRASSLAND net primary productivity precipitation–productivity relation DROUGHT climate change NDVI
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