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   968篇
  免费   1篇
  国内免费   4篇
系统科学   20篇
理论与方法论   5篇
现状及发展   169篇
研究方法   112篇
综合类   616篇
自然研究   51篇
  2018年   4篇
  2017年   8篇
  2014年   4篇
  2013年   5篇
  2012年   58篇
  2011年   115篇
  2010年   14篇
  2009年   5篇
  2008年   48篇
  2007年   49篇
  2006年   50篇
  2005年   57篇
  2004年   39篇
  2003年   42篇
  2002年   47篇
  2001年   38篇
  2000年   25篇
  1999年   14篇
  1995年   5篇
  1993年   4篇
  1992年   16篇
  1991年   9篇
  1990年   7篇
  1989年   6篇
  1988年   12篇
  1987年   9篇
  1986年   14篇
  1985年   16篇
  1984年   12篇
  1983年   9篇
  1982年   10篇
  1981年   4篇
  1980年   8篇
  1979年   4篇
  1978年   12篇
  1977年   8篇
  1976年   15篇
  1975年   9篇
  1974年   9篇
  1973年   11篇
  1972年   6篇
  1971年   21篇
  1970年   29篇
  1969年   6篇
  1968年   14篇
  1967年   15篇
  1966年   12篇
  1965年   9篇
  1964年   3篇
  1957年   3篇
排序方式: 共有973条查询结果,搜索用时 15 毫秒
41.
    
G R Robinson  B I Scott 《Experientia》1973,29(8):1039-1040
  相似文献   
42.
The chromosomes of eukaryotic cells are separated from the cytoplasm by the nuclear envelope. The nuclear envelope includes two riveted membranes, plus embedded pore complexes that mediate nuclear import and export. In this sense, the nuclear envelope is truly a border zone. However, the envelope also links directly to chromosomes, and anchors two major infrastructures--the nuclear lamina and Tpr filaments--to the nuclear perimeter. Proteins of the nuclear envelope mediate a variety of fundamental activities, including DNA replication, gene expression and silencing, chromatin organization, cell division, apoptosis, sperm nuclear remodeling, the behavior of pronuclei, cell fate determination, nuclear migration and cell polarity. Furthermore, mutations in nuclear lamins and lamin-binding proteins cause tissue-specific inherited diseases. This special issue of Cell and Molecular Life Sciences is devoted to recent major advances in the characterization of nuclear envelope proteins and their roles. We offer here an overview of the topics covered in this issue of CMLS, and also discuss the emerging recognition that the nuclear envelope is an organelle critical for a wide range of genetic and developmental activity in multicellular organisms.  相似文献   
43.
    
We have explored the properties of a Ca2+-dependent cell-signalling pathway that becomes active when cultured equine sweat gland cells are stimulated with ATP. The ATP-regulated, Ca2+-influx pathway allowed Sr2+ to enter the cytoplasm but permitted only a minimal influx of Ba2+. Experiments in which cells were repeatedly stimulated with ATP suggested that Sr2+, but not Ba2+, could become incorporated into the agonist-sensitive, cytoplasmic Ca2+ store. Further evidence for this was provided by experiments using ionomycin, a Ca2+ ionophore which has no affinity for Sr2+.  相似文献   
44.
45.
K Wilson  K J Turner 《Experientia》1976,32(4):523-524
The serum IgE levels measured by RIST correlated closely with those obtained by the single radioimmunodiffusion method. Values for husband and wife were closely related as were those between father and daughter but in contrast to previous observations no significant relationship existed between IgE levels for mother and son.  相似文献   
46.
    
F W McCormick  A Scott 《Experientia》1966,22(4):228-229
  相似文献   
47.
Summary Adult loop-tail heterozygotes (Lp/+) from a stock ofLp-mice which consistently fail to show head wobbling exhibit normal brain morphology with respect to size and shape of lateral ventricles and nearby nuclei. Loop-tail heterozygotes from a head wobbling stock ofLp-mice show enlargement and deformity of the lateral ventricles.Supported by research grant HD09562 from the National Institutes of Health.  相似文献   
48.
49.
    
When causal forces are specified, the expected direction of the trend can be compared with the trend based on extrapolation. Series in which the expected trend conflicts with the extrapolated trend are called contrary series. We hypothesized that contrary series would have asymmetric forecast errors, with larger errors in the direction of the expected trend. Using annual series that contained minimal information about causality, we examined 671 contrary forecasts. As expected, most (81%) of the errors were in the direction of the causal forces. Also as expected, the asymmetries were more likely for longer forecast horizons; for six‐year‐ahead forecasts, 89% of the forecasts were in the expected direction. The asymmetries were often substantial. Contrary series should be flagged and treated separately when prediction intervals are estimated, perhaps by shifting the interval in the direction of the causal forces. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
50.
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