全文获取类型
收费全文 | 659157篇 |
免费 | 61913篇 |
国内免费 | 503篇 |
出版年
2018年 | 10345篇 |
2017年 | 10005篇 |
2016年 | 10490篇 |
2015年 | 9179篇 |
2014年 | 10857篇 |
2013年 | 16035篇 |
2012年 | 19157篇 |
2011年 | 23951篇 |
2010年 | 16999篇 |
2009年 | 15728篇 |
2008年 | 20763篇 |
2007年 | 22837篇 |
2006年 | 16067篇 |
2005年 | 16042篇 |
2004年 | 15792篇 |
2003年 | 15623篇 |
2002年 | 15347篇 |
2001年 | 26766篇 |
2000年 | 26921篇 |
1999年 | 21155篇 |
1998年 | 7141篇 |
1997年 | 7511篇 |
1996年 | 7178篇 |
1995年 | 6720篇 |
1994年 | 6631篇 |
1993年 | 6532篇 |
1992年 | 17893篇 |
1991年 | 17558篇 |
1990年 | 17582篇 |
1989年 | 17181篇 |
1988年 | 16133篇 |
1987年 | 15299篇 |
1986年 | 14025篇 |
1985年 | 14662篇 |
1984年 | 11951篇 |
1983年 | 10331篇 |
1982年 | 7781篇 |
1981年 | 7016篇 |
1980年 | 6546篇 |
1979年 | 11416篇 |
1978年 | 8831篇 |
1977年 | 8303篇 |
1976年 | 7944篇 |
1975年 | 8814篇 |
1974年 | 9552篇 |
1973年 | 9431篇 |
1972年 | 9054篇 |
1971年 | 8308篇 |
1970年 | 6912篇 |
1969年 | 6685篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
991.
992.
993.
994.
S Glazer M M Vartanova N N Konstantinova 《Biulleten' eksperimental'no? biologii i meditsiny》1985,100(10):414-415
Significant adverse correlation of the fetus mass and the degree of its hydration was noted at term in rats with placental insufficiency induced by ligation of about 40% of preplacental vessels on the 16th day of gestation. Disorders revealed in transplacental water-salt metabolism are apparently of some importance for the pathogenesis of fetal growth retardation. Even moderate retardation alters fetal respiratory activity in anoxia, which is associated with the changes in the function of respiratory centres and neuromuscular abnormalities. 相似文献
995.
996.
997.
G G Hillebrand A H McCluskey K A Abbott G G Revich K L Beattie 《Nucleic acids research》1984,12(7):3155-3171
A method has been developed for simultaneous comparison of the propensity of a DNA polymerase to misincorporate at different points on a natural template-primer. In this method elongation of a [5'-32P] primer, annealed to a bacteriophage template strand, is carried out in the presence of only three dNTPs (highly purified by HPLC). Under these conditions the rate of primer elongation (monitored by gel electrophoresis/autoradiography) is limited by the rate of misincorporation at template positions complementary to the missing dNTP. Variations in the rate of elongation (revealed by autoradiographic banding patterns) reflect variations in the propensity for misincorporation at different positions along the template. The effect on primer elongation produced by addition of a chemically modified dNTP to 'minus' reactions reveals the mispairing potential of the modified nucleotide during DNA synthesis. By use of this electrophoretic assay of misincorporation we have demonstrated that the fidelity of E. coli DNA polymerase I varies greatly at different positions along a natural template, and that BrdUTP and IodUTP can be incorporated in place of dCTP during chain elongation catalyzed by this enzyme. 相似文献
998.
999.
1000.
The main condition of completing the process of adaptation of the body to the effect of an external factor is the return of the homeostatic system parameters to their initial levels or their stabilization at a new level. The article considers the state of incomplete adaptation (IA) based on the process of the stabilization of systemic reactions (respiration and blood circulation) on repeated exposure to extreme environmental factors (hypoxia and cold) associated with the excitation of the central regulatory mechanisms of the respiratory center system performing a compensatory–protective function. It is postulated that a change in the afferent information flows (the thresholds of excitation and reactivity of the peripheral receptor systems) forms the basis of IA. The IA state is supposed to persist for an indefinitely long period of time due to insufficient functional reserves and to be the cause of psychosomatic pathology. 相似文献