全文获取类型
收费全文 | 984707篇 |
免费 | 103076篇 |
国内免费 | 596篇 |
出版年
2018年 | 9469篇 |
2017年 | 8959篇 |
2016年 | 12678篇 |
2015年 | 16537篇 |
2014年 | 19416篇 |
2013年 | 28284篇 |
2012年 | 31462篇 |
2011年 | 32306篇 |
2010年 | 21982篇 |
2009年 | 20260篇 |
2008年 | 28876篇 |
2007年 | 30019篇 |
2006年 | 28115篇 |
2005年 | 27062篇 |
2004年 | 26733篇 |
2003年 | 25794篇 |
2002年 | 25143篇 |
2001年 | 41536篇 |
2000年 | 41121篇 |
1999年 | 33080篇 |
1998年 | 12391篇 |
1997年 | 12666篇 |
1996年 | 12116篇 |
1995年 | 11109篇 |
1994年 | 10786篇 |
1993年 | 10837篇 |
1992年 | 27337篇 |
1991年 | 26897篇 |
1990年 | 26148篇 |
1989年 | 25635篇 |
1988年 | 23606篇 |
1987年 | 22590篇 |
1986年 | 21034篇 |
1985年 | 21083篇 |
1984年 | 17526篇 |
1983年 | 15131篇 |
1982年 | 11647篇 |
1981年 | 10627篇 |
1980年 | 9874篇 |
1979年 | 16430篇 |
1978年 | 12939篇 |
1977年 | 11917篇 |
1976年 | 11294篇 |
1975年 | 12595篇 |
1974年 | 13553篇 |
1973年 | 13399篇 |
1972年 | 12145篇 |
1971年 | 11099篇 |
1970年 | 9768篇 |
1969年 | 9470篇 |
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
991.
992.
W.M.F. Jongen P.H.M. Lohman M.J. Kottenhagen G.M. Alink F. Berends J.H. Koeman 《Mutation research》1981,81(2):203-213
Several short-term mammalian test systems were used for mutagenicity testing of the organic solvent dichloromethane. The compound was negative in the forward mutation test on the HGPRT locus in Chinese hamster cells and the unscheduled DNA synthesis test in both human and hamster cells. In the test on DNA synthesis inhibition, dichloromethane caused an aspecific inhibition in both human and hamster cells, but in this test the effect did not indicate a DNA-damaging action. A weak positive effect was found in the test on sister-chromatid exchanges in hamster cells. 相似文献
993.
Regulation of G(1) cell-cycle progression by oncogenes and tumor suppressor genes. 总被引:13,自引:0,他引:13
Progression of resting quiescent G(0) cells into early G(1) and transition across the restriction point are highly regulated processes. Mutation of proto-oncogenes and tumor suppressor genes regulating these transitions are targeted during oncogenesis. Recent work has underscored the importance of the G(0) to early G(1) transition and metabolism to neoplastic cells. 相似文献
994.
995.
996.
997.
M Janowski L Baugnet-Mahiec J Merregaert L de Saint-Georges A Sassen J N Ihle J R Maisin 《Comptes rendus des séances de la Société de biologie et de ses filiales》1980,174(5):832-839
Two distinct rat propagates of a radiation leukemia virus (RadLV-Rs) from the C57BL mouse respectively induced characteristic leukemogenic effects. These were found to be related with the infection titers of the isolates, but not with either their antigenic specificities or their viral and proviral genome sequences. 相似文献
998.
999.
By means of the histostereometrical method, peculiarities of the thyroid gland formation have been studied in the lemming (Dicrostonyx torquatus) fetuses and newborns at the stage of the population quantity drop, as well specificity of the organ's morphofunctional state during the postnatal period. On the 14th prenatal day the thyroid gland already has the follicular structure. Up to the 19th day progressive follicular growth, accumulation of colloid and increase of its density occur. On the 19th-20th days, as well as in newborn animals, there are certain signs, demonstrating as essential activation of the thyroid gland function. In the newborn animals cavities of the completely formed follicles are devastated. During the postnatal period again growth of follicles, accumulation of colloid are observed, signs of hypersecretion of the hypophysis appear. 相似文献
1000.
Human long-latency auditory evoked potentials were studied during simulation with variable-amplitude pulse sequences from a sound source moving to and from the subject. The N1 peak parameters were shown to depend on an accurate estimate of the direction of the change in the distance to the sound source. Differences in the processing of signals that simulated the approaching and/or distancing of the sound source were found in the N1 and P2 component parameters of on- and off-responses as was a more pronounced long negative potential shift in the evoked response to the approaching source as compared to the distancing source. 相似文献