全文获取类型
收费全文 | 665435篇 |
免费 | 170533篇 |
国内免费 | 29879篇 |
出版年
2018年 | 8559篇 |
2017年 | 8032篇 |
2016年 | 10275篇 |
2015年 | 12136篇 |
2014年 | 14287篇 |
2013年 | 19008篇 |
2012年 | 21916篇 |
2011年 | 23080篇 |
2010年 | 17975篇 |
2009年 | 21215篇 |
2008年 | 21718篇 |
2007年 | 22233篇 |
2006年 | 20185篇 |
2005年 | 19465篇 |
2004年 | 19540篇 |
2003年 | 18250篇 |
2002年 | 18637篇 |
2001年 | 27919篇 |
2000年 | 25783篇 |
1999年 | 24839篇 |
1998年 | 14214篇 |
1997年 | 13920篇 |
1996年 | 13016篇 |
1995年 | 12941篇 |
1994年 | 12290篇 |
1993年 | 11963篇 |
1992年 | 21920篇 |
1991年 | 22103篇 |
1990年 | 22361篇 |
1989年 | 21427篇 |
1988年 | 20131篇 |
1987年 | 18762篇 |
1986年 | 17448篇 |
1985年 | 17033篇 |
1984年 | 13962篇 |
1983年 | 11773篇 |
1982年 | 9762篇 |
1981年 | 8706篇 |
1980年 | 8482篇 |
1979年 | 12799篇 |
1978年 | 10386篇 |
1977年 | 9700篇 |
1976年 | 9235篇 |
1975年 | 9785篇 |
1974年 | 10991篇 |
1973年 | 10778篇 |
1972年 | 10274篇 |
1971年 | 9520篇 |
1970年 | 8426篇 |
1969年 | 8293篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
V A Shuklinov 《Tsitologiia》1985,27(3):268-275
The paper reports reasons for a possibility of tumour regression due to selection of low-malignant and differentiating clones. Experimental evidence is provided supporting this view. 相似文献
992.
Paracoenia fumosalis Cresson previously known only from the USA and Canada is recorded in the Palaearctic Region for the first time. The adults were collected near a thermal hydrosulfuric spring in the Geiser Valley in Kamchatka. A key to species of the genus Paracoenia occurring in Russia is given. 相似文献
993.
994.
Mitochondrial DNA variation was examined in one of the southem most populations of domestic reindeer, inhabiting Tyva Republic (Tuva). In Tuvinian population sequence polymorphism of the mitochondrial DNA D-loop region was demonstrated. In a sample of 29 individuals 7 mitotypes were distinguished, pointing to the preservation of rather high level of genetic diversity in this population. 相似文献
995.
996.
The ECF™ lateral flow assay test is marketed to detect non-pregnancy in mares. The objectives of the present study were to determine the accuracy of the ECF test, the accuracy of the electronic reader accompanying the ECF test, and agreement between two human readers and the electronic reader. Serum samples were collected from anestrus, cycling but not inseminated, and inseminated mares, and were evaluated with the ECF™ test (EDP Biotech Company, Knoxville, TN, USA) at The Ohio State University and at the EDP Biotech Laboratory. Specificity ranged from 0.07 to 0.16, the negative predictive value ranged from 0.15 to 0.33, and accuracy ranged from 0.43 to 0.52. The electronic reader did not add improve the accuracy or predictive values of the test. Based on the electronic reader, 80.0% of the serum samples collected from the anestrus mares were false positives; Readers 1 and 2 had 60.0 and 33.3% false positives, respectively. For samples collected during the estrous cycle, 83.9% were false positives by the electronic reader, whereas Readers 1 and 2 had 43.7 and 26.4% false positives. We concluded that, regardless of whether the test strips were evaluated by a human or electronic reader, this assay was not accurate for determination of the non-pregnant mare. 相似文献
997.
998.
Fossil plants of the Chingandzha flora were studied from volcanogenic sediments of the Chingandzha and Rond formations on
the northern coast of the Sea of Okhotsk. It was concluded that all platanaceous leaves earlier described in this flora as
different taxa belong to one highly variable species, Pseudoprotophyllum cordatum Samyl. emend. Shczepetov et Golovneva. 相似文献
999.
Molecular Probing of the HPV-16 E6 Protein Alpha Helix Binding Groove with Small Molecule Inhibitors
Anne Rietz Dino P. Petrov Matthew Bartolowits Marsha DeSmet V. Jo Davisson Elliot J. Androphy 《PloS one》2016,11(2)
The human papillomavirus (HPV) HPV E6 protein has emerged as a central oncoprotein in HPV-associated cancers in which sustained expression is required for tumor progression. A majority of the E6 protein interactions within the human proteome use an alpha-helix groove interface for binding. The UBE3A/E6AP HECT domain ubiquitin ligase binds E6 at this helix-groove interface. This enables formation of a trimeric complex with p53, resulting in destruction of this tumor suppressor. While recent x-ray crystal structures are useful, examples of small molecule probes that can modulate protein interactions at this interface are limited. To develop insights useful for potential structure-based design of ligands for HPV E6, a series of 2,6-disubstituted benzopyranones were prepared and tested as competitive antagonists of E6-E6AP helix-groove interactions. These small molecule probes were used in both binding and functional assays to evaluate recognition features of the E6 protein. Evidence for an ionic functional group interaction within the helix groove was implicated by the structure-activity among the highest affinity ligands. The molecular topographies of these protein-ligand interactions were evaluated by comparing the binding and activities of single amino acid E6 mutants with the results of molecular dynamic simulations. A group of arginine residues that form a rim-cap over the E6 helix groove offer compensatory roles in binding and recognition of the small molecule probes. The flexibility and impact on the overall helix-groove shape dictated by these residues offer new insights for structure-based targeting of HPV E6. 相似文献
1000.