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   723004篇
  免费   81076篇
  国内免费   903篇
  804983篇
  2018年   6494篇
  2016年   8899篇
  2015年   12647篇
  2014年   14750篇
  2013年   20283篇
  2012年   23548篇
  2011年   23883篇
  2010年   16054篇
  2009年   14589篇
  2008年   21130篇
  2007年   21893篇
  2006年   20497篇
  2005年   19594篇
  2004年   19463篇
  2003年   18441篇
  2002年   18140篇
  2001年   33325篇
  2000年   33541篇
  1999年   26449篇
  1998年   9142篇
  1997年   9313篇
  1996年   8825篇
  1995年   8384篇
  1994年   8079篇
  1993年   7923篇
  1992年   21847篇
  1991年   21538篇
  1990年   20877篇
  1989年   20115篇
  1988年   18651篇
  1987年   17475篇
  1986年   16454篇
  1985年   16186篇
  1984年   13270篇
  1983年   11562篇
  1982年   8636篇
  1981年   7683篇
  1980年   7140篇
  1979年   12583篇
  1978年   9891篇
  1977年   8833篇
  1976年   8198篇
  1975年   9479篇
  1974年   10152篇
  1973年   9930篇
  1972年   8956篇
  1971年   8114篇
  1970年   7066篇
  1969年   6810篇
  1968年   6214篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Long the sole domain of physiologists and electrical engineers, ion channel biophysics is going molecular, and with a vengeance. This summary of a recent meeting devoted to ion channel biophysics shows that the integration of techniques, reinforced by active communication among scientists of diverse backgrounds, is extremely potent.  相似文献   
102.
103.
Agapophytinae subf.n. is a highly diverse lineage of Australasian Therevidae, comprising eight described and two new genera: Agapophytus Guérin‐Méneville, Acupalpa Kröber, Acraspisa Kröber, Belonalys Kröber, Bonjeania Irwin & Lyneborg, Parapsilocephala Kröber, Acatopygia Kröber, Laxotela Winterton & Irwin, Pipinnipons gen.n. and Patanothrix gen.n. A genus‐level cladistic analysis of the subfamily was undertaken using sixty‐eight adult morphological characters and c. 1000 base pairs of the elongation factor‐1α (EF‐1α) protein coding gene. The morphological data partition produced three most parsimonious cladograms, whereas the molecular data partition gave a single most parsimonious cladogram, which did not match any of the cladograms found in the morphological analysis. The level of congruence between the data partitions was determined using the partition homogeneity test (HTF) and Wilcoxon signed ranks test. Despite being significantly incongruent in at least one of the incongruence tests, the partitions were combined in a simultaneous analysis. The combined data yielded a single cladogram that was better supported than that of the individual partitions analysed separately. The relative contributions of the data partitions to support for individual nodes on the combined cladogram were investigated using Partitioned Bremer Support. The level of support for many nodes on the combined cladogram was non‐additive and often greater than the sum of support for the respective nodes on individual partitions. This synergistic interaction between incongruent data partitions indicates a common phylogenetic signal in both partitions. It also suggests that criteria for partition combination based solely on incongruence may be misleading. The phylogenetic relationships of the genera are discussed using the combined data. A key to genera of Agapophytinae is presented, with genera diagnosed and figured. Two new genera are described: Patanothrix with a new species (Pat. skevingtoni) and Pat. wilsoni (Mann) transferred from Parapsilocephala, and Pipinnipons with a new species (Pip. kroeberi). Pipinnipons fascipennis (Kröber) is transferred from Squamopygia Kröber and Pip. imitans (Mann) is transferred from Agapophytus. Agapophytus bicolor (Kröber) is transferred from Parapsilocephala. Agapophytus varipennis Mann is synonymised with Aga. queenslandi Kröber and Aga. flavicornis Mann is synonymised with Aga. pallidicornis (Kröber).  相似文献   
104.
105.
106.
107.
108.
109.
Biotin and protein synthesis in rat liver   总被引:5,自引:0,他引:5  
  相似文献   
110.
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