全文获取类型
收费全文 | 371976篇 |
免费 | 28038篇 |
国内免费 | 93篇 |
出版年
2018年 | 4604篇 |
2017年 | 4610篇 |
2016年 | 5590篇 |
2015年 | 5281篇 |
2014年 | 6694篇 |
2013年 | 9557篇 |
2012年 | 11549篇 |
2011年 | 12313篇 |
2010年 | 8320篇 |
2009年 | 7376篇 |
2008年 | 10616篇 |
2007年 | 11105篇 |
2006年 | 10644篇 |
2005年 | 13039篇 |
2004年 | 13188篇 |
2003年 | 11746篇 |
2002年 | 9830篇 |
2001年 | 15839篇 |
2000年 | 15712篇 |
1999年 | 12021篇 |
1998年 | 3818篇 |
1997年 | 3776篇 |
1996年 | 3427篇 |
1995年 | 3164篇 |
1992年 | 9531篇 |
1991年 | 9726篇 |
1990年 | 9487篇 |
1989年 | 9491篇 |
1988年 | 8753篇 |
1987年 | 8245篇 |
1986年 | 7530篇 |
1985年 | 7852篇 |
1984年 | 6333篇 |
1983年 | 5317篇 |
1982年 | 3614篇 |
1981年 | 3180篇 |
1980年 | 3132篇 |
1979年 | 5962篇 |
1978年 | 4646篇 |
1977年 | 4230篇 |
1976年 | 3993篇 |
1975年 | 4803篇 |
1974年 | 5313篇 |
1973年 | 5269篇 |
1972年 | 4790篇 |
1971年 | 4485篇 |
1970年 | 3896篇 |
1969年 | 3795篇 |
1968年 | 3554篇 |
1967年 | 3201篇 |
排序方式: 共有10000条查询结果,搜索用时 310 毫秒
981.
982.
Cycling virgin female rats were treated with clomiphene citrate (CC) during dioestrus of the reproductive cycle. Animals were sacrificed 2 days after the initial injection and their vaginal tissue was examined by scanning electron microscopy. Animals treated with one dose of CC had an epithelium consistent with a prolonged dioestrus. Treatment with CC for 2 days induced changes in the epithelium that had no resemblance to any normal hormonally controlled event in the vagina. It was found that CC had effects consistent with progesterone alone as well as effects unique to this superovulatory drug. 相似文献
983.
984.
A Schellenberger I Heinroth G Hübner 《Hoppe-Seyler's Zeitschrift für physiologische Chemie》1967,348(5):506-511
985.
986.
987.
As a result of selection of rats possessing a high threshold of neuro-muscular exitability in comparison with rats possessing a low threshold of neuro-muscular exitability, certain changes take place in the structures that are connected with the learning process: the visual cortex is wider, volumes of the pyramidal cells in the fields CA1 and CA3 of the hippocampus are increased, density of the glial elements in the fornix is essentially increased and that of neurons in the septal nucleus is decreased. 相似文献
988.
I Martínez de Mara?ón N Chaudanson N Joly P Gervais 《Biotechnology and bioengineering》1999,65(2):176-181
Thermal resistance of Saccharomyces cerevisiae was found to be drastically dependent on the kinetics of heat perturbation. Yeasts were found to be more resistant to a plateau of 1 h at 50 degrees C after a slope of temperature increase (slow and linear temperature increments) than after a shock (sudden temperature change). Thermotolerance was mainly acquired between 40-50 degrees C during a heat slope, i.e., above the maximal temperature of growth. The death of the yeasts subjected to a heat shock might be related to the loss of membrane integrity: intracellular contents extrusion, i.e., membrane permeabilization, was found to precede cell death. However, the permeabilization did not precede cell death during a heat slope and, therefore, membrane permeabilization was a consequence rather than a cause of cell death. During a slow temperature increase, yeasts which remain viable may have time to adapt their plasma membrane and thus maintain membrane integrity. 相似文献
989.
990.