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   953篇
  免费   119篇
  2021年   8篇
  2019年   10篇
  2018年   19篇
  2017年   10篇
  2016年   22篇
  2015年   24篇
  2014年   35篇
  2013年   41篇
  2012年   51篇
  2011年   43篇
  2010年   30篇
  2009年   24篇
  2008年   34篇
  2007年   47篇
  2006年   29篇
  2005年   34篇
  2004年   35篇
  2003年   35篇
  2002年   40篇
  2001年   20篇
  2000年   37篇
  1999年   31篇
  1998年   15篇
  1997年   13篇
  1996年   13篇
  1995年   10篇
  1994年   9篇
  1993年   15篇
  1992年   21篇
  1991年   18篇
  1990年   14篇
  1989年   18篇
  1988年   8篇
  1987年   7篇
  1986年   13篇
  1985年   13篇
  1984年   10篇
  1982年   5篇
  1981年   8篇
  1980年   6篇
  1979年   13篇
  1978年   12篇
  1977年   11篇
  1975年   12篇
  1974年   9篇
  1973年   9篇
  1972年   14篇
  1971年   13篇
  1970年   7篇
  1875年   4篇
排序方式: 共有1072条查询结果,搜索用时 281 毫秒
971.
972.
973.
974.
975.
Michael Ruse's writings explore what sociobiology says about morality. Further, he claims that sociobiology undermines the base for Christian morality. After responding to criticisms of Ruse, especially those of Arthur Peacocke, I lay a base for meeting his challenge.  相似文献   
976.
NBR1 (named as next to BRCA1) was originally cloned as a candidate gene for the ovarian cancer antigen CA125, using expression cloning with the anti-CA125 Ig, OC125. NBR1 has been of interest due to its position close to BRCA1, although no involvement in breast or ovarian cancer has been demonstrated. Recently, the antigen CA125 has been cloned, and identified as a new mucin, MUC16, entirely different from NBR1. The function of NBR1 remains unknown. To investigate its function, a yeast two-hybrid study was performed to identify interacting protein partners that may reflect a biological role for this protein. Here, we show that NBR1 interacts with two proteins; fasciculation and elongation protein zeta-1 (FEZ1), a PKCzeta interacting protein, and calcium and integrin binding protein (CIB), which is associated with polo-like kinases Fnk/Snk and the Alzheimer's disease presenilin 2 protein. Co-transfection of FEZ1 and NBR1 showed overlapping localization in the cytoplasm, whereas coexpression of NBR1 and CIB resulted in a shift of CIB protein expression from the nucleus to the perinuclear compartment. FEZ1 is highly expressed in the brain and in situ hybridization analysis of Nbr1 showed that its expression is also regulated in the murine brain during development. These data suggest that NBR1 may function, through interaction with CIB and FEZ1 in cell signalling pathways, with a developmentally restricted expression suggesting a possible role in neural development.  相似文献   
977.
978.
Developmental changes in surface properties ofDictyostelium discoideum cells have been detected by partitioning. Changes occurring between 0 and 6 h development were not affected by tunicamycin but subsequent changes associated with formation of presumptive spore cells were inhibited. It would seem that only the latter changes are dependent on glyco-protein synthesis.  相似文献   
979.
Evolutionary and ecological hypotheses of the freshwater mussel subfamily Ambleminae are intensely geographically biased—a consequence of the complete exclusion of Mesoamerican taxa in phylogenetic reconstructions of the clade. We set out to integrate a portion of the Mesoamerican freshwater mussel assemblage into existing hypotheses of amblemine classification and evolution by generating a molecular phylogeny that includes four previously unsampled Mesoamerican genera and nine species endemic to that region. Given the traditionally hypothesized affinity to Nearctic mussels and the understanding that classification should reflect common ancestry, we predicted that (a) Mesoamerican genera would be recovered as members of the recognized tribes of the Ambleminae, and (b) genera would be supported as monophyletic. The mutilocus phylogeny (COI + 28S + 16S) reported herein does not fully support either of those hypotheses. Neither Cyrtonaias nor Psorula were supported as monophyletic and we predict several other Mesoamerica genera are also non‐monophyletic. The reconstructed phylogeny recovered four independent lineages of Mesoamerican freshwater mussels and these clades are distributed across the phylogeny of the Ambleminae, including the tribe Quadrulini (Megalonaias), Lampsilini (two lineages: Cyrtonaias explicata/Sphenonaias microdon, and Pachynaias), and a previously unrecognized, exclusively Mesoamerican and Rio Grande clade consisting of the genera Psoronaias, Psorula and Popenaias. The latter clade possesses several morphological characteristics that distinguish it from its sister taxon, tribe Lampsilini, and we recognize this newly identified Mesoamerican clade as a fifth tribe of the Ambleminae attributable to the Popenaiadini Heard & Guckert, 1970. This revised classification more completely recognizes the suprageneric diversity of the Ambleminae.  相似文献   
980.
Many mammal species adopt marking postures that elevate their scent deposits. The most extreme of these is handstand marking, in which an individual reverses against an upright object, flings its hind legs into the air above its back and balances bipedally on its fore feet. The resulting anogenital deposit is thus raised one full body length above ground level. It has been suggested that this energetically costly form of marking serves to provide conspecifics with information about the marker's body size and hence competitive ability. However, this explanation assumes that the height of an individuals’ deposit does reflect accurately its body size, an assumption that has never been tested in any hand‐standing species. This study investigated the relationship between body size and handstand mark height in a wild population of dwarf mongooses (Helogale parvula) in South Africa. We found that although body size and marking height were correlated positively for female dwarf mongooses, they were not related for males. Male dwarf mongooses (who are subject to intrasexual competition from outside their group) invested more heavily in anogenital range marking, marking at three times the female frequency and placing their deposits significantly higher than females (although they were not dimorphic). Males that were particularly vulnerable to rivals (i.e. those that were small for their age) tended to mark higher than more robust age‐mates, in keeping with the predictions of Adams & Mesterton‐Gibbons’ (1995, J. Theor. Biol.175, 405–421). model of deceptive threat communication. These findings suggest strongly that the height of anogenital scent deposits is of social significance to dwarf mongooses.  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