全文获取类型
收费全文 | 223869篇 |
免费 | 14977篇 |
国内免费 | 45篇 |
出版年
2021年 | 1773篇 |
2018年 | 3125篇 |
2017年 | 3023篇 |
2016年 | 3666篇 |
2015年 | 3201篇 |
2014年 | 4437篇 |
2013年 | 6321篇 |
2012年 | 7542篇 |
2011年 | 8060篇 |
2010年 | 5721篇 |
2009年 | 4876篇 |
2008年 | 7197篇 |
2007年 | 7477篇 |
2006年 | 7178篇 |
2005年 | 6703篇 |
2004年 | 6848篇 |
2003年 | 6567篇 |
2002年 | 6524篇 |
2001年 | 9274篇 |
2000年 | 8953篇 |
1999年 | 6987篇 |
1998年 | 2122篇 |
1997年 | 1953篇 |
1996年 | 1819篇 |
1992年 | 5467篇 |
1991年 | 5677篇 |
1990年 | 5650篇 |
1989年 | 5620篇 |
1988年 | 5212篇 |
1987年 | 4862篇 |
1986年 | 4442篇 |
1985年 | 4677篇 |
1984年 | 3696篇 |
1983年 | 3025篇 |
1982年 | 2013篇 |
1981年 | 1722篇 |
1980年 | 1725篇 |
1979年 | 3338篇 |
1978年 | 2576篇 |
1977年 | 2375篇 |
1976年 | 2330篇 |
1975年 | 2826篇 |
1974年 | 3117篇 |
1973年 | 3084篇 |
1972年 | 2746篇 |
1971年 | 2604篇 |
1970年 | 2212篇 |
1969年 | 2158篇 |
1968年 | 2031篇 |
1967年 | 1797篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
201.
Experiments in mice have demonstrated that in the presence of influenza infection the suppressing effect of virulent shigellae on the secondary humoral and cell-mediated immune response is enhanced. Under such conditions avirulent shigellae can also show suppressing effect which is usually absent in these organisms. 相似文献
202.
G T Sukhikh I V Bogdashin L V Van'ko 《Biulleten' eksperimental'no? biologii i meditsiny》1985,99(4):399-401
It has been shown that at late periods after immobilization stress there is an essential reduction in the cytostatic activity of CBA mice splenocytes detected by inhibition of mastocytoma P 815 cell proliferation in the test with 3H-uridine incorporation. The cytostatic activity returns to normal 5 to 14 days after stress. The changes in the cytolytic and cytostatic activity of mouse splenocytes following stress are correlated and a possible biological value of changes in the immunoassays for the host are discussed. 相似文献
203.
The processes of the cultivation of N. meningitidis, serogroups A, B and C, in a liquid synthetic culture medium have been studied. Strictly group-specific biomass has been obtained. The maximum productivity at all stages of the batch cultivation of N. meningitidis strains 125 and 133 in this medium does not differ from that at similar stages of cultivation in modified Cohen-Wheller semisynthetic medium. In the serotype antigen preparations obtained from N. meningitidis strain 125 grown in the above-mentioned liquid synthetic culture medium basic polypeptides with a molecular weight of 33000, 36000 and 41000 D have been detected. Their presence in N. meningitidis cells is linked with the growth phase of the population. 相似文献
204.
P V Sergeev A S Dukhanin A V Seme?kin 《Biulleten' eksperimental'no? biologii i meditsiny》1987,104(12):678-681
In has been shown that cortisol immobilized on polyvinylpyrrolidone (PVP-GC) affects cyclic AMP production stimulated by adenosine and isoproterenol in rat thymocytes. This effect of PVP-GC is specific for cortisol: antiglucocorticoid progesterone (at a concentration of 10(-5) M) inhibited completely the action of PVP-GC on the intracellular cAMP level. It is suggested that cortisol effect on cAMP production is one of the mechanisms of glucocorticoid hormone action in target cells. 相似文献
205.
206.
A new cestode species, Diphyllobothrium klebanovskii sp. n., is described on the basis of experimental examination and morphological study of 51 specimens expelled from men in lower part of the Amur river and 18 specimens expelled from golden hamsters. The larval stage of this cestode is plerocercoid of type F, which is localized in muscles of Oncorhynchus keta and O. gorbuscha. D. klebanovskii sp. n. is a marine species, it differs from D. latum and other species of the genus Diphyllobothrium. 相似文献
207.
208.
Biophysics - HMGB1 is one of the key proteins of the cell. HMGB1 performs its main functions predominantly in the cell nucleus, as an essential component of DNA–protein and multiprotein... 相似文献
209.
Biophysics - A technology has been developed for the preparation of novel chloramine compounds related to adenosine derivatives. The optical absorption characteristics of... 相似文献
210.
Biophysics - A change in the content of energy substrates in myocardial mitochondria depending upon the vibration frequency and the duration of the total vertical vibration exposure was studied... 相似文献