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   174篇
  免费   26篇
  2022年   3篇
  2021年   3篇
  2020年   1篇
  2018年   2篇
  2017年   3篇
  2016年   1篇
  2015年   7篇
  2014年   4篇
  2013年   10篇
  2012年   11篇
  2011年   13篇
  2010年   11篇
  2009年   7篇
  2008年   9篇
  2007年   8篇
  2006年   4篇
  2005年   4篇
  2004年   10篇
  2003年   8篇
  2002年   9篇
  2001年   10篇
  2000年   6篇
  1999年   7篇
  1998年   5篇
  1997年   2篇
  1996年   2篇
  1995年   1篇
  1994年   1篇
  1993年   2篇
  1992年   2篇
  1991年   4篇
  1990年   1篇
  1989年   3篇
  1988年   3篇
  1987年   2篇
  1985年   3篇
  1983年   4篇
  1982年   1篇
  1981年   1篇
  1980年   2篇
  1979年   1篇
  1975年   1篇
  1973年   1篇
  1972年   1篇
  1970年   1篇
  1969年   1篇
  1967年   1篇
  1964年   1篇
  1963年   1篇
  1961年   1篇
排序方式: 共有200条查询结果,搜索用时 640 毫秒
191.
192.
Intact Sendai virus particles were radiolabeled by the use of chloramine-T and Na 125I. The method described is reproducible, efficient and appropriate for the preparation of large quantities of biologically active virus with relatively high specific activity. Gel electrophoresis analysis of the radiolabeled virus revealed that approx. 50% of the total 125I incorporated in the virus are associated with the two viral envelope glycoproteins, while the remaining 50% are evenly distributed throughout the other viral polypeptides. The 125I-virus particles were used to study some of the kinetic parameters of the interaction between Sendai virus particles and human erythrocytes. Binding of virus particles at 4 °C is irreversible, non-cooperative and exhibits a characteristic saturation curve. A maximum of 1–2 × 103 virus particles bound per cell was derived from the saturation curve. Non-radioactive native virus particles as well as isolated glycophorin molecules competitively inhibit binding of the 125I-virus particles to human erythrocytes. Incubation at 37 °C of the virus-erythrocyte complex resulted in the release of about 33% of the bound virus to the surrounding medium.  相似文献   
193.
194.
Endophytic fungi compose a significant part of plant microbiomes. However, while a small number of fungal taxa have proven beneficial impact, the vast majority of fungal endophytes remain uncharacterized, and the drivers of fungal endophyte community (FEC) assembly are not well understood. Here, we analysed FECs in three cereal crops-related wild grasses – Avena sterilis, Hordeum spontaneum and Aegilops peregrina – that grow in mixed populations in natural habitats. Taxa in Ascomycota class Dothideomycetes, particularly the genera Alternaria and Cladosporium, were the most abundant and prevalent across all populations, but there was also high incidence of basidiomyceteous yeasts of the class Tremellomycetes. The fungal community was shaped to large extent by stochastic processes, as indicated by high level of variation even between individuals from local populations of the same plant species, and confirmed by the neutral community model and Raup-Crick index. Nevertheless, we still found strong determinism in FEC assembly with both incidence and abundance data sets. Substantial differences in community composition across host species and locations were revealed. Our research demonstrated that assembly of FECs is affected by stochastic as well as deterministic processes and suggests strong effects of environment heterogeneity and plant species on community composition. In addition, a small number of taxa had high incidence and abundance in all of the 15 populations. These taxa represent an important part of the core FEC and might be of general functional importance.  相似文献   
195.
This article focuses on agricultural planning and work relations in the Lakhish regional settlement project in 1950s Israel. During this period, Jewish immigrants from Arab countries – considered the other of allegedly Modern and Western Israeli society – were sent to settle the new frontier, in order to establish Jewish sovereignty over former Palestinian land. I discuss the ways in which agricultural planning and the organization of the work process created a relationship of dependency between the settlers and the settling institutions. I show, that the plans were shaped by Orientalist assumptions concerning the nature of the settlers, their social and family relationships and their cognitive abilities. I argue that it was these plans and the work relations they engendered, that doomed the settlers from the start, undermining their ability to form functioning cooperative communities. The settlers, however, were not passive objects of state policies but rather displayed patterns of resistance to state regulation.  相似文献   
196.
197.
The morphology of the lumbar spine is crucial for upright posture and bipedal walking in hominids. The excellent preservation of the lumbar spine of Kebara 2 provides us a rare opportunity to observe a complete spine and explore its functionally relevant morphology. The lumbar spine of Kebara 2 is analyzed and compared with the lumbar spines of modern humans and late Pleistocene hominids. Although no size differences between the vertebral bodies and pedicles of Kebara 2 and modern humans are found, significant differences in the size and orientation of the transverse processes (L1‐L4), and the laminae (L5, S1) are demonstrated. The similarity in the size of the vertebral bodies and pedicles of Kebara 2 and modern humans suggests similarity in axial load transmission along the lumbar spine. The laterally projected (L2‐L4) and the cranially oriented (L1, L3) transverse processes of Kebara 2 show an advantage for lateral flexion of the lumbar spine compared with modern humans. The characteristic morphology of the lumbar spine of Kebara 2 might be related to the wide span of its pelvic bones. Am J Phys Anthropol 142:549–557, 2010. © 2010 Wiley‐Liss, Inc.  相似文献   
198.
Gene regulatory networks for animal development are the underlying mechanisms controlling cell fate specification and differentiation. The architecture of gene regulatory circuits determines their information processing properties and their developmental function. It is a major task to derive realistic network models from exceedingly advanced high throughput experimental data. Here we use mathematical modeling to study the dynamics of gene regulatory circuits to advance the ability to infer regulatory connections and logic function from experimental data. This study is guided by experimental methodologies that are commonly used to study gene regulatory networks that control cell fate specification. We study the effect of a perturbation of an input on the level of its downstream genes and compare between the cis-regulatory execution of OR and AND logics. Circuits that initiate gene activation and circuits that lock on the expression of genes are analyzed. The model improves our ability to analyze experimental data and construct from it the network topology. The model also illuminates information processing properties of gene regulatory circuits for animal development.  相似文献   
199.
200.
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