全文获取类型
收费全文 | 406606篇 |
免费 | 38275篇 |
国内免费 | 2963篇 |
出版年
2018年 | 14252篇 |
2017年 | 12699篇 |
2016年 | 11044篇 |
2015年 | 6512篇 |
2014年 | 7261篇 |
2013年 | 9538篇 |
2012年 | 14393篇 |
2011年 | 22210篇 |
2010年 | 18037篇 |
2009年 | 14034篇 |
2008年 | 17747篇 |
2007年 | 19250篇 |
2006年 | 8164篇 |
2005年 | 8153篇 |
2004年 | 8249篇 |
2003年 | 8322篇 |
2002年 | 7686篇 |
2001年 | 11711篇 |
2000年 | 11694篇 |
1999年 | 9622篇 |
1998年 | 3825篇 |
1997年 | 4021篇 |
1996年 | 3994篇 |
1995年 | 3724篇 |
1994年 | 3701篇 |
1993年 | 3625篇 |
1992年 | 8432篇 |
1991年 | 8164篇 |
1990年 | 7898篇 |
1989年 | 7819篇 |
1988年 | 7343篇 |
1987年 | 7293篇 |
1986年 | 6719篇 |
1985年 | 6877篇 |
1984年 | 5743篇 |
1983年 | 5173篇 |
1982年 | 4111篇 |
1981年 | 3952篇 |
1980年 | 3586篇 |
1979年 | 5933篇 |
1978年 | 4634篇 |
1977年 | 4438篇 |
1976年 | 4235篇 |
1975年 | 4582篇 |
1974年 | 5036篇 |
1973年 | 4927篇 |
1972年 | 4817篇 |
1971年 | 4395篇 |
1970年 | 3648篇 |
1969年 | 3667篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
211.
David Skelly 《BMC biology》2010,8(1):136
A new study of divergence in freshwater fish provides strong evidence of rapid, temperature-mediated adaptation. This study
is particularly important in the ongoing debate over the extent and significance of evolutionary response to climate change
because divergence has occurred in relatively few generations in spite of ongoing gene flow and in the aftermath of a significant
genetic bottleneck, factors that have previously been considered obstacles to evolution. Climate change may thus be more likely
to foster contemporary evolutionary responses than has been anticipated, and I argue here for the importance of investigating
their possible occurrence. 相似文献
212.
W. Blake Christensbn 《Biotechnic & histochemistry》1949,24(3):165-170
Albert's method, of staining diphtheria cultures consists of staining a fixed smear for one minute (some laboratories stain for five minutes) with a solution containing toluidine blue and malachite (or methyl) green, washing with water, and applying Albert's iodine for one minute. This procedure is discussed and criticized, and in addition the mechanism of the stain is elucidated. Also, the procedure which involves staining a fixed smear for one minute with Loeffler's alkaline methylene blue solution is discussed and criticized.
To overcome the objections to the above staining methods, a different method is proposed. This consists of staining a fixed smear with an acid solution of toluidine blue, washing with water, applying Albert's iodine for one minute, washing with water, and finally applying a safranin solution for 15-20 seconds. The theoretical basis for this method is presented. 相似文献
To overcome the objections to the above staining methods, a different method is proposed. This consists of staining a fixed smear with an acid solution of toluidine blue, washing with water, applying Albert's iodine for one minute, washing with water, and finally applying a safranin solution for 15-20 seconds. The theoretical basis for this method is presented. 相似文献
213.
214.
215.
216.
217.
218.
AS it is not widely appreciated that diffusion within complex media can be strikingly and often qualitatively different from that in simple liquids such as water, there is confusion concerning transport processes across biological membranes1,2. We would like to draw attention to some fundamental differences between the diffusion process in simple liquids and that in more complex media-non-porous networks of hydrophobic polymers and biological membranes. 相似文献
219.
220.
R factors of compatibility group A 总被引:4,自引:0,他引:4