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   258篇
  免费   21篇
  279篇
  2023年   1篇
  2022年   2篇
  2021年   8篇
  2020年   2篇
  2019年   5篇
  2018年   4篇
  2017年   6篇
  2016年   3篇
  2015年   11篇
  2014年   23篇
  2013年   19篇
  2012年   26篇
  2011年   18篇
  2010年   14篇
  2009年   10篇
  2008年   13篇
  2007年   13篇
  2006年   13篇
  2005年   15篇
  2004年   10篇
  2003年   10篇
  2002年   9篇
  2001年   3篇
  2000年   2篇
  1999年   2篇
  1998年   3篇
  1997年   2篇
  1996年   3篇
  1995年   3篇
  1994年   2篇
  1993年   1篇
  1992年   4篇
  1991年   1篇
  1990年   2篇
  1988年   1篇
  1987年   1篇
  1986年   2篇
  1984年   2篇
  1983年   1篇
  1982年   1篇
  1980年   4篇
  1970年   1篇
  1969年   1篇
  1967年   1篇
  1964年   1篇
排序方式: 共有279条查询结果,搜索用时 10 毫秒
21.
22.
23.
The distribution of wildlife parasites in a landscape is intimately tied to the spatial distribution of hosts. In parasite species, including many gastrointestinal parasites, with obligate or common environmental life stages, the dynamics of the parasite can also be strongly affected by geophysical components of the environment. This is especially salient in host species, for example humans and macaques, which thrive across a wide variety of habitat types and quality and so are exposed to a wealth of environmentally resilient parasites. Here, we examine the effect of environmental and anthropogenic components of the landscape on the prevalence, intensity, and species diversity of gastrointestinal parasites across a metapopulation of long-tailed macaques on the island of Bali, Indonesia. Using principal-components analysis, we identified significant interaction effects between specific environmental and anthropogenic components of the landscape, parsing the Balinese landscape into anthropogenic (PC1), mixed environment (PC2), and non-anthropogenic (PC3) components. Further, we determined that the anthropogenic environment can mitigate the prevalence and intensity of specific gut parasites and the intensity of the overall community of gut parasites, but that non-anthropogenically driven landscape components have no significant effect in increasing or reducing the intensity or prevalence of the community of gut parasites in Balinese macaques.  相似文献   
24.
25.
The dinuclear V(V) complexes (VOL)2O (L = SAE (1), SAMP (2), SAP (3)) have been synthesized from VO(acac)2 and the corresponding tridentate ligands LH2 in methanol under reflux conditions and subsequent air oxidation in organic solvent. They have been characterized by IR and NMR spectroscopy, by thermogravimetric analysis, and by single crystal X-ray diffraction for 1 and 2. DFT calculations were carried out for a better understanding of the vibrational pattern, principally the V-O related vibrations. Complex [VO(SAP)]2O (3) catalyzes the epoxidation of cyclooctene by TBHP in water in the absence of any added solvent with good selectivity.  相似文献   
26.
27.
The emerging manifesto, center of the essay collection this commentary is part of, points out that primatology is a primate's science and field of endeavor. It is about primates, and constructed and carried out by primates. But the relationships between different primates involved in primatology cannot be described merely as scientific, zoological, or conservatory. A main point emerging from this perspective is that the relationships amongst primates (as scientists and as subjects) are affected by primatologists' experiences outside of academic science and within the cultural schema that we acquire as members of human societies. My contribution focuses on the primatologists and their sometimes discussed, but too often ignored, cultural and ethnic contexts as influences on how they study, think about, and interact with other primates. In our views and bonds with other primates, do national, class, and ethnic factors count?  相似文献   
28.
29.
30.
All-optical histology using ultrashort laser pulses   总被引:10,自引:0,他引:10  
As a means to automate the three-dimensional histological analysis of brain tissue, we demonstrate the use of femtosecond laser pulses to iteratively cut and image fixed as well as fresh tissue. Cuts are accomplished with 1 to 10 microJ pulses to ablate tissue with micron precision. We show that the permeability, immunoreactivity, and optical clarity of the tissue is retained after pulsed laser cutting. Further, samples from transgenic mice that express fluorescent proteins retained their fluorescence to within microns of the cut surface. Imaging of exogenous or endogenous fluorescent labels down to 100 microm or more below the cut surface is accomplished with 0.1 to 1 nJ pulses and conventional two-photon laser scanning microscopy. In one example, labeled projection neurons within the full extent of a neocortical column were visualized with micron resolution. In a second example, the microvasculature within a block of neocortex was measured and reconstructed with micron resolution.  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