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   216篇
  免费   15篇
  2021年   6篇
  2020年   2篇
  2019年   2篇
  2015年   6篇
  2014年   7篇
  2013年   7篇
  2012年   15篇
  2011年   12篇
  2010年   5篇
  2009年   4篇
  2008年   3篇
  2007年   3篇
  2006年   4篇
  2005年   6篇
  2004年   6篇
  2003年   8篇
  2002年   3篇
  2000年   4篇
  1999年   6篇
  1997年   5篇
  1996年   4篇
  1995年   3篇
  1994年   7篇
  1993年   3篇
  1992年   4篇
  1991年   2篇
  1990年   8篇
  1989年   6篇
  1988年   5篇
  1985年   2篇
  1984年   4篇
  1983年   2篇
  1981年   3篇
  1979年   3篇
  1978年   2篇
  1977年   2篇
  1976年   2篇
  1975年   4篇
  1974年   3篇
  1973年   6篇
  1972年   2篇
  1971年   2篇
  1968年   3篇
  1963年   2篇
  1958年   2篇
  1942年   3篇
  1939年   2篇
  1938年   2篇
  1936年   3篇
  1935年   3篇
排序方式: 共有231条查询结果,搜索用时 203 毫秒
61.
Stereopsis, the perception of depth from small differences between the images in the two eyes, provides a rich model for investigating the cortical construction of surfaces and space. Although disparity-tuned cells have been found in a large number of areas in macaque visual cortex, stereoscopic processing in these areas has never been systematically compared using the same stimuli and analysis methods. In order to examine the global architecture of stereoscopic processing in primate visual cortex, we studied fMRI activity in alert, fixating human and macaque subjects. In macaques, we found strongest activation to near/far compared to zero disparity in areas V3, V3A, and CIPS. In humans, we found strongest activation to the same stimuli in areas V3A, V7, the V4d topolog (V4d-topo), and a caudal parietal disparity region (CPDR). Thus, in both primate species a small cluster of areas at the parieto-occipital junction appears to be specialized for stereopsis.  相似文献   
62.
Occupational medicine is a key component of a comprehensive occupational health and safety program in support of laboratory animal research and production facilities. The mission of the department is to maximize employee health and productivity utilizing a population health management approach, which includes measurement and analysis of health benefits utilization. The department works in close cooperation with other institutional health and safety professionals to identify potential risks from exposure to physical, chemical, and biological hazards in the workplace. As soon as exposures are identified, the department is responsible for formulating and providing appropriate medical surveillance programs. Occupational medicine is also responsible for targeted delivery of preventive and wellness services; management of injury, disease, and disability; maintenance of medical information; and other clinic services required by the institution. Recommendations are provided for the organization and content of occupational medicine programs for animal research facilities.  相似文献   
63.
We have shown previously that centrosomes and other microtubule-organizing centers (MTOCs) attach to the apical intermediate filament (IF) network in CACO-2 cells. In this cell line, intermediate filaments do not disorganize during mitosis. Therefore, we speculated that the trigger of the G(2)-M boundary may also detach MTOCs from their IF anchor. If that was the case, at least one of the proteins involved in the attachment must be phosphorylated by p34(cdc2) (cdk1). Using confocal microscopy and standard biochemical analysis, we found that p34(cdc2)-mediated phosphorylation indeed released MTOCs from IFs in permeabilized cells. In isolated, immunoprecipitated multiprotein complexes containing both gamma-tubulin and cytokeratin 19, p34(cdc2) phosphorylated only one protein, and phosphorylation released cytokeratin 19 from the complexes. We conclude that this as yet unidentified protein is a part of the molecular mechanism that attaches MTOCs to IFs in interphase.  相似文献   
64.
The presence of a sodium-dependent, saturable uptake process is described in basolateral membranes of rat renal cortex for L-glutamine. Concentration-dependence studies indicate the presence of multiple transport systems withK m 1 of 0.032 mM and V1 of 0.028 nmol/mg of protein per min, andK m 2 of 17.6 mM and V2 of 17.6 nmol/mg of protein per min. Lysine completely inhibits the high-affinity, low-capacityK m system and partially inhibits the low-affinity, high-capacity system. Cystine and other dibasic amino acids also affect glutamine uptake.  相似文献   
65.
Class II tetramer reagents for eleven common DR alleles and a DP allele prevalent in the world population were used to identify SARS-CoV-2 CD4+ T cell epitopes. A total of 112, 28 and 42 epitopes specific for Spike, Membrane and Nucleocapsid, respectively, with defined HLA-restriction were identified. Direct ex vivo staining of PBMC with tetramer reagents was used to define immunodominant and subdominant T cell epitopes and estimate the frequencies of these T cells in SARS-CoV-2 exposed and naïve individuals. Majority of SARS-CoV-2 epitopes identified have <67% amino acid sequence identity with endemic coronaviruses and are unlikely to elicit high avidity cross-reactive T cell responses. Four SARS-CoV-2 Spike reactive epitopes, including a DPB1*04:01 restricted epitope, with ≥67% amino acid sequence identity to endemic coronavirus were identified. SARS-CoV-2 T cell lines for three of these epitopes elicited cross-reactive T cell responses to endemic cold viruses. An endemic coronavirus Spike T cell line showed cross-reactivity to the fourth SARS-CoV-2 epitope. Three of the Spike cross-reactive epitopes were subdominant epitopes, while the DPB1*04:01 restricted epitope was a dominant epitope. Frequency analyses showed Spike cross-reactive T cells as detected by tetramers were present at relatively low frequency in unexposed people and only contributed a small proportion of the overall Spike-specific CD4+ T cells in COVID-19 convalescent individuals. In total, these results suggested a very limited number of SARS-CoV-2 T cells as detected by tetramers are capable of recognizing ccCoV with relative high avidity and vice versa. The potentially supportive role of these high avidity cross-reactive T cells in protective immunity against SARS-CoV-2 needs further studies.  相似文献   
66.
Grass pollen allergy is one of the most important allergic diseases world-wide. Several meadow grasses, like timothy grass and rye grass, contribute to allergic sensitizations, but also allergens from extensively cultivated cereals, especially rye, make a profound contribution. The group 4 allergens are well known as important major allergens of grasses. We have cloned for the first time group 4 sequences from Phleum pratense, Lolium perenne, Secale cereale, Triticum aestivum, and Hordeum vulgare, and investigated the IgE-reactivity of recombinant Phl p 4 as a candidate for allergy diagnostic and therapeutic applications.  相似文献   
67.
68.
The porphyropsin-vitamin A2 cycle has been found heretofore only in the retinas of bony fishes capable of existence in fresh water. Cyclostomes, due to their primitive and isolated phylogenetic position, might be expected to possess the rhodopsin-vitamin A1 cycle common to marine elasmobranchs, almost all marine teleosts, and all terrestrial vertebrates so far examined. Yet the anadromous sea lamprey, Petromyzon marinus, possesses primarily the porphyropsin system, like an anadromous teleost. This observation greatly extends the phylogenetic association of vitamin A2 with the capacity for freshwater existence. Compared with freshwater and anadromous teleosts, the lamprey retina contains the porphyropsin system in extremely low concentration. The remaining eye tissues, like the retina, contain both vitamins A1 and A2, the latter greatly predominant. The livers of larval and adult lampreys, however, appear to contain vitamin A1 alone. This situation also is not without teleost precedent, since the carp and certain anadromous salmonids display similar reversals of vitamin A pattern in the liver and eye tissues.  相似文献   
69.
70.
On page 333, Vol. 25, No. 3, January 20, 1942, the cuts for Figs. 1 and 3 should be interchanged. The legends should remain where they now appear.  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