全文获取类型
收费全文 | 60688篇 |
免费 | 4967篇 |
国内免费 | 28篇 |
专业分类
65683篇 |
出版年
2022年 | 413篇 |
2021年 | 858篇 |
2020年 | 528篇 |
2019年 | 639篇 |
2018年 | 833篇 |
2017年 | 774篇 |
2016年 | 1365篇 |
2015年 | 2402篇 |
2014年 | 2525篇 |
2013年 | 3350篇 |
2012年 | 4266篇 |
2011年 | 4271篇 |
2010年 | 2768篇 |
2009年 | 2450篇 |
2008年 | 3547篇 |
2007年 | 3623篇 |
2006年 | 3412篇 |
2005年 | 3435篇 |
2004年 | 3382篇 |
2003年 | 3158篇 |
2002年 | 3126篇 |
2001年 | 728篇 |
2000年 | 538篇 |
1999年 | 740篇 |
1998年 | 867篇 |
1997年 | 600篇 |
1996年 | 609篇 |
1995年 | 593篇 |
1994年 | 574篇 |
1993年 | 599篇 |
1992年 | 540篇 |
1991年 | 466篇 |
1990年 | 394篇 |
1989年 | 406篇 |
1988年 | 404篇 |
1987年 | 344篇 |
1986年 | 340篇 |
1985年 | 399篇 |
1984年 | 447篇 |
1983年 | 374篇 |
1982年 | 460篇 |
1981年 | 413篇 |
1980年 | 363篇 |
1979年 | 244篇 |
1978年 | 297篇 |
1977年 | 287篇 |
1976年 | 235篇 |
1975年 | 219篇 |
1974年 | 242篇 |
1973年 | 222篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
M Shadidy X Caubit R Olsen O M Seternes U Moens S Krauss 《Biochimica et biophysica acta》1999,1446(3):295-307
We have identified mouse and human FKBP60, a new member of the FKBP gene family. FKBP60 shares strongest homology with FKBP65 and SMAP. FKBP60 contains a hydrophobic signal peptide at the N-terminus, 4 peptidyl-prolyl cis/trans isomerase (PPIase) domains and an endoplasmic reticulum retention motif (HDEL) at the C-terminus. Immunodetection of HA-tagged FKBP60 in NIH-3T3 cells suggests that FKBP60 is segregated to the endoplasmic reticulum. Northern blot analysis shows that FKBP60 is predominantly expressed in heart, skeletal muscle, lung, liver and kidney. With N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide as a substrate, recombinant GST-FKBP60 is shown to accelerate effectively the isomerization of the peptidyl-prolyl bond. This isomerization activity is inhibited by FK506. mFKBP60 binds Ca2+ in vitro, presumably by its C-terminal EF-hand Ca2+ binding motif, and is phosphorylated in vivo. hFKBP60 has been mapped to 7p12 and/or 7p14 by fluorescence in situ hybridization (FISH). 相似文献
2.
The phylogeny of the fungus gnat family Mycetophilidae (Diptera) is reconstructed with a focus on the species‐rich and taxonomically difficult subfamilies Gnoristinae and Mycomyinae. The multigene phylogenetic analyses are based on five nuclear (18S, 28S, CAD, MCS, ITS2) and four mitochondrial (12S, 16S, COI, CytB) gene markers. The analyses strongly support the monophyly of Mycetophilidae and the subfamilies Manotinae, Sciophilinae, Leiinae, and Mycomyinae, although Gnoristinae is paraphyletic with respect to Mycetophilinae. All the genera and groups of genera included are supported as monophyletic, except for Acomoptera Vockeroth, Boletina Staeger, Dziedzickia Johannsen, Ectrepesthoneura Enderlein, and Neoempheria Osten Sacken. Ancestral character state reconstructions were applied to two morphological features present in Gnoristinae and Mycomyinae (i.e. presence of setae on wing membrane and wing vein R4) in order to assess their evolution. The wing vein R4 appears as an unstable character, spread throughout different clades. A dated phylogeny of the family Mycetophilidae showed that most of the subfamilies of Mycetophilidae originated and diversified during the Cretaceous. The youngest subfamilies, originated in the Paleogene, appear to be Mycomyinae and Mycetophilinae. 相似文献
3.
This paper is concerned with gene survival in a population which may increase without density dependence according to a generalization of the Moran model for haploid individuals. A selective advantage to one allele and the possibility of differential reproductive rates are allowed. Simple conditions are given for ultimate homozygosity to be certain and for the possibility of ultimate polymorphism. The results complement and extend those of Heyde (1981, 1982). 相似文献
4.
5.
6.
7.
8.
9.
B Spyropoulos P B Moens J Davidson J A Lowden 《American journal of human genetics》1981,33(3):375-380
Chi-square analyses of new data as well as data previously reported by Myrianthopoulos have shown that grandparents of Tay-Sachs carriers die from proportionally the same causes as grandparents of noncarriers. It is unlikely that there is any advantage to being a Tay-Sachs carrier insofar as resistance to tuberculosis is concerned. Our results are further evidence to support Fraikor's claim that the high carrier frequency of the allele in Ashkenazi Jews is probably caused by a combination of founder effect, genetic drift, and differential immigration patterns. 相似文献
10.
Peter Buchwald 《Theoretical biology & medical modelling》2009,6(1):5-13