首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2594篇
  免费   77篇
  国内免费   1篇
  2672篇
  2023年   4篇
  2022年   7篇
  2021年   18篇
  2020年   14篇
  2019年   11篇
  2018年   18篇
  2017年   22篇
  2016年   28篇
  2015年   34篇
  2014年   44篇
  2013年   90篇
  2012年   298篇
  2011年   848篇
  2010年   361篇
  2009年   439篇
  2008年   63篇
  2007年   42篇
  2006年   38篇
  2005年   41篇
  2004年   34篇
  2003年   21篇
  2002年   21篇
  2001年   14篇
  2000年   18篇
  1999年   13篇
  1998年   4篇
  1997年   8篇
  1996年   5篇
  1995年   9篇
  1994年   4篇
  1993年   7篇
  1992年   3篇
  1991年   8篇
  1990年   12篇
  1989年   8篇
  1988年   3篇
  1987年   7篇
  1986年   3篇
  1985年   3篇
  1984年   3篇
  1983年   3篇
  1979年   3篇
  1978年   4篇
  1975年   3篇
  1973年   3篇
  1972年   5篇
  1971年   3篇
  1970年   2篇
  1969年   2篇
  1968年   4篇
排序方式: 共有2672条查询结果,搜索用时 0 毫秒
81.
Journal of Plant Growth Regulation - Although fruit decay in sweet cherries has been studied in some detail, information is still scarce about the possible role of phytohormones during postharvest....  相似文献   
82.
83.
Recent studies have shown the microbial biofilms adherent to plant biomass in the gastrointestinal tracts of humans and other herbivores are quite different to planktonic populations. If these biofilm communities are to be properly characterized by metagenomics methods, then the microbial desorption methods used must ensure the phylogenetic diversity and genetic potential recovered is biologically valid. To that end, we describe here two different methods for desorbing microbes tightly adherent to plant biomass; and used PCR-DGGE analyses of the Bacteria and Archaea rrs genes to show both these desorption methods were effective in recovering the adherent microbial biofilm with no apparent biases in microbe recovery. We also present a derivation of the ??repeated bead beating and column (RBB+C) purification?? method of DNA extraction that results in the recovery of high molecular weight DNA. These DNA samples can be fragmented and size fractionated by sucrose density gradient centrifugation, bypassing the use of gel-plug lysis and pulsed-field gel electrophoresis separation of DNA for metagenomic library constructions.  相似文献   
84.
85.
86.
Huntingtin containing an expanded polyglutamine causes neuronal death and Huntington disease. Although expanded huntingtin is found in virtually every cell type, its toxicity is limited to neurons of certain areas of the brain, such as cortex and caudate/putamen. In affected areas of the brain, expanded huntingtin is not found in its intact monomeric form. It is found instead in the form of N-terminal fragments, oligomers and polymers, all of which accumulate in the cortex. Whereas the oligomer is mostly soluble, the polymers and the fragments associate with each other and with other proteins to form the insoluble inclusions characteristic of the disease. It is likely that the aggregates containing expanded huntingtin are toxic to neurons, but it remains to be determined whether the oligomer or the inclusion is the toxic species.Key Words: huntingtin, polyglutamine, aggregation, oligomer, polymer, N-terminal fragments, transglutaminase  相似文献   
87.
88.
Valle LG  Santamaria S 《Mycologia》2005,97(6):1335-1347
The presence of zygospores in the genus Orphella is newly described. We found zygospores in three species of the genus, O. catalaunica, O. coronata and O. helicospora, which are all the species of the genus known from the Iberian territory. Zygospores are associated with a heterothallic conjugating sexual process in O. coronata, whereas in O. catalaunica and O. helicospora, they form homothallically. In all instances, zygospores are consistently associated with an organized pattern of sterile cells, forming structures comparable to those present with asexual trichospores. We compare the ontogeny of Orphella zygospores with that found in the harpellid Genistellospora homothallica and discuss the possible close relationship of Orphella with Kickxellales (Zygomycetes). We report O. coronata in Spain for the first time, replacing all previous records of O. haysii. Results are supported with line drawings and photographs.  相似文献   
89.
Gene flow between domesticated plants and their wild relatives is one of the major evolutionary processes acting to shape their structure of genetic diversity. Earlier literature, in the 1970s, reported on the interfertility and the sympatry of wild, weedy and cultivated sorghum belonging to the species Sorghum bicolor in most regions of sub-Saharan Africa. However, only a few recent surveys have addressed the geographical and ecological distribution of sorghum wild relatives and their genetic structure. These features are poorly documented, especially in western Africa, a centre of diversity for this crop. We report here on an exhaustive in situ collection of wild, weedy and cultivated sorghum assembled in Mali and in Guinea. The extent and pattern of genetic diversity were assessed with 15 SSRs within the cultivated pool (455 accessions), the wild pool (91 wild and weedy forms) and between them. F (ST) and R (ST) statistics, distance-based trees, Bayesian clustering methods, as well as isolation by distance models, were used to infer evolutionary relationships within the wild-weedy-crop complex. Firstly, our analyses highlighted a strong racial structure of genetic diversity within cultivated sorghum (F (ST) = 0.40). Secondly, clustering analyses highlighted the introgressed nature of most of the wild and weedy sorghum and grouped them into two eco-geographical groups. Such closeness between wild and crop sorghum could be the result of both sorghum's domestication history and preferential post-domestication crop-to-wild gene flow enhanced by farmers' practices. Finally, isolation by distance analyses showed strong spatial genetic structure within each pool, due to spatially limited dispersal, and suggested consequent gene flow between the wild and the crop pools, also supported by R (ST) analyses. Our findings thus revealed important features for the collection, conservation and biosafety of domesticated and wild sorghum in their centre of diversity.  相似文献   
90.
Abstract The cell surface of strains of Aeromonas salmonicida possessing an additional surface protein (A-protein) was shown to be more hydrophobic than strains devoid of this protein, using the techniques of phase partitioning, agglutination in the presence of ammonium sulphate and hydrophobic interaction chromatography.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号