全文获取类型
收费全文 | 1457922篇 |
免费 | 132688篇 |
国内免费 | 1499篇 |
出版年
2021年 | 18111篇 |
2019年 | 16359篇 |
2018年 | 18801篇 |
2017年 | 17508篇 |
2016年 | 28992篇 |
2015年 | 43151篇 |
2014年 | 51189篇 |
2013年 | 77600篇 |
2012年 | 40808篇 |
2011年 | 30186篇 |
2010年 | 45407篇 |
2009年 | 46241篇 |
2008年 | 27923篇 |
2007年 | 26258篇 |
2006年 | 30484篇 |
2005年 | 31401篇 |
2004年 | 30525篇 |
2003年 | 27911篇 |
2002年 | 25903篇 |
2001年 | 43676篇 |
2000年 | 40979篇 |
1999年 | 38451篇 |
1998年 | 26355篇 |
1997年 | 26302篇 |
1996年 | 25513篇 |
1995年 | 23681篇 |
1994年 | 23372篇 |
1993年 | 22575篇 |
1992年 | 31997篇 |
1991年 | 30128篇 |
1990年 | 28589篇 |
1989年 | 29149篇 |
1988年 | 26625篇 |
1987年 | 24976篇 |
1986年 | 23706篇 |
1985年 | 25354篇 |
1984年 | 24513篇 |
1983年 | 21463篇 |
1982年 | 21253篇 |
1981年 | 20433篇 |
1980年 | 19083篇 |
1979年 | 20423篇 |
1978年 | 18863篇 |
1977年 | 18075篇 |
1976年 | 16944篇 |
1975年 | 16539篇 |
1974年 | 17130篇 |
1973年 | 17445篇 |
1972年 | 14906篇 |
1971年 | 13529篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
982.
983.
984.
S Lock 《BMJ (Clinical research ed.)》1986,293(6539):154-155
985.
W. B. Chodirker 《CMAJ》1984,130(4):343-344
986.
987.
Methanobacterium thermoautotrophicum, an archaebacterium, possesses the first and last enzymes of the diaminopimelic acid pathway for lysine biosynthesis, dihydrodipicolinate synthase, and diaminopimelate decarboxylase. It does not have saccharopine dehydrogenase, the last enzyme of the aminoadipate pathway for lysine biosynthesis. The dihydrodipicolinate synthase is inhibited but not repressed by lysine. We conclude that this microbe uses the diaminopimelate pathway for synthesis of lysine.Deceased. 相似文献
988.
M Kh Ga?nutdinov S I Mirmakhmudova N M Mullagalieva Ia Kh Turakulov 《Biulleten' eksperimental'no? biologii i meditsiny》1984,97(3):293-295
Addition of a thermostable cytoplasmic fraction leads to the uncoupling of oxidative phosphorylation of the mitochondria. In hyperthyrosis such an effect manifests itself more powerfully than in the control. Addition of the thermostable cytoplasmic fraction induces electrogenic phosphate transport via the mitochondrial membrane. In hyperthyrosis, the activity of the thermostable inducer of phosphate transport in the cytoplasm increases. The functioning of the phosphate cycle may be the cause of the uncoupling of oxidative phosphorylation of the mitochondria during the disease in question. 相似文献
989.
990.
Additive reagents have been investigated to improve the stability of methanolic Wright's stain. The addition of ammonium halides, monoalkyiamine hydrochlorides, dialkylamine hydrochlorides or trialkylamine hydrochlorides to methanolic Wright's stain was found to enhance the stability of stain components in methanol. No change in performance is observed with these additives present. Random precipitation in the stain solution was still observed with the addition of ammonium halides and monoalkyiamine hydrochlorides. No precipitation was found in stain solutions containing hydrochlorides of most dialkylamines and trialkylamines. Of the compounds evaluated, 0.6% diethylamine hydrochloride added to methanolic stain solutions produced the most desirable overall results. Mechanisms of stabilization and precipitation in these stain solutions are proposed, Essentially, separation of the thiazine-eosinate ion pair through interaction with an appropriate additive increases stain stability. The solubilities of thiazine-eosinate or additive cation-eosinate ion pairs in methanol determine the formation of precipitate in such stain solutions. 相似文献