全文获取类型
收费全文 | 346795篇 |
免费 | 25738篇 |
国内免费 | 1258篇 |
出版年
2021年 | 2799篇 |
2018年 | 4358篇 |
2017年 | 4264篇 |
2016年 | 6983篇 |
2015年 | 10720篇 |
2014年 | 11409篇 |
2013年 | 13388篇 |
2012年 | 13549篇 |
2011年 | 11599篇 |
2010年 | 8299篇 |
2009年 | 7547篇 |
2008年 | 8442篇 |
2007年 | 8559篇 |
2006年 | 8137篇 |
2005年 | 13680篇 |
2004年 | 12191篇 |
2003年 | 10233篇 |
2002年 | 7692篇 |
2001年 | 13395篇 |
2000年 | 12730篇 |
1999年 | 10830篇 |
1998年 | 3148篇 |
1997年 | 3053篇 |
1996年 | 2955篇 |
1995年 | 2772篇 |
1994年 | 2699篇 |
1992年 | 9134篇 |
1991年 | 9091篇 |
1990年 | 9157篇 |
1989年 | 8868篇 |
1988年 | 8390篇 |
1987年 | 7865篇 |
1986年 | 7010篇 |
1985年 | 7297篇 |
1984年 | 5565篇 |
1983年 | 4723篇 |
1982年 | 3130篇 |
1981年 | 2907篇 |
1979年 | 5188篇 |
1978年 | 3910篇 |
1977年 | 3495篇 |
1976年 | 3489篇 |
1975年 | 4123篇 |
1974年 | 4481篇 |
1973年 | 4531篇 |
1972年 | 4027篇 |
1971年 | 3765篇 |
1970年 | 3335篇 |
1969年 | 3112篇 |
1968年 | 2960篇 |
排序方式: 共有10000条查询结果,搜索用时 229 毫秒
991.
992.
993.
994.
The proton magnetic resonance (PMR) spectra of thyroid cell membranes and their total lipid extracts, in the presence of 1-anilino-8-naphthalenesulfonate (ANS), have been studied. The addition of ANS causes a shifting of the head group PMR signal, a splitting of the signal into two components and an increase in total spectral intensity. The data suggest that ANS interacts with phospholipid in the membrane as it does in total lipid vesicles. Evidence is also presented for the removal of lipids from the membrane, by ANS, and the subsequent formation of micelles. The membrane results are compatred with our earlier work on the interaction of ANS with egg phosphatidycholine (P.C.) vesicles and the results are used in explaining the inhibition of iodide transport in isolated thyroid slices. 相似文献
995.
N K Shinton 《BMJ (Clinical research ed.)》1978,2(6153):1694-1695
996.
Ciliates were collected from a freshwater sulfuretum, Lake Cisó, which is part of a gypsum karstic area whose main feature is Lake Banyoles (Girona, Spain). Chromatium, Lamprocystis and Chlorobium are the major phototrophic sulfur bacteria in Lake Cisó. Blooms of a photosynthetic cryptomonad (up to 5 X 10(5) ind ml-1) were found at the metalimnion. The community of ciliates could be divided in three groups: aerobic, cosmopolitan, genera such as Stentor and Vorticella, in the epilimnion; a large population (up to 10(4) ind ml-1) of Coleps, adapted to low concentrations of both oxygen and sulfide, together with a few individuals of the equally sulfide-tolerant genus Paramecium, in the metalimnion, and anaerobic, true sulfide-loving genera such as Plagiopyla and Metopus, in the hypolimnion, where sulfide concentration was between 0.6 and 1.2 mM. 相似文献
997.
New mutations in the pRM promoter of bacteriophage lambda 总被引:1,自引:0,他引:1
998.
B S Kasavina Iu F Ma?chuk T V Ukhina 《Biulleten' eksperimental'no? biologii i meditsiny》1983,95(3):44-45
Activity of phosphodiesterases disintegrating cAMP and cGMP in the cornea, sclera and ciliary body was investigated in health and in different stages of experimental herpetic keratitis. The problems concerning the role of the cyclase system in the pathogenesis of herpetic keratitis and the possibility of applying some of the drugs to the disease treatment are discussed. 相似文献
999.
L A Novikova S M Dracheva A S Zubatov V N Luzikov 《Biokhimii?a (Moscow, Russia)》1982,47(8):1401-1408
The proteins of submitochondrial particles solubilized with 0.1% Triton X-100 were separated by polyacrylamide gel electrophoresis. Hydrolysis of several proteinase substrates was registered directly in the gel after completion of electrophoresis. According to the data obtained the inner mitochondrial membrane contains one or two enzymes which catalyze hydrolysis of cytochrome c as well as one or two enzymes splitting synthetic substrate of trypsin-like proteinases, e. g. N-alpha-benzoyl-L-arginine-p-nitroanilide (BAPA) and N-alpha-benzoyl-L-arginine-beta-naphthylamide (BANA). Submitochondrial particles were shown to catalyze hydrolysis of 3H-labelled cytochrome c. This activity is suppressed by the same inhibitors as the hydrolysis of mitochondrial translation products, i. e. phenyl-methylsulfonylfluoride, p-chloromercuribenzosulfonate, leupeptin and antipain. Presumably these two processes are catalyzed by the same enzyme localized in the inner mitochondrial membrane. Physiological functions of BAPA- and BANA-hydrolyzing enzyme(s) are still unclear. 相似文献
1000.
Mechanism of stabilization of synaptosomes with alpha-tocopherol during exposure to phospholipase A2
A N Erin V I Skrypin L L Prilipko V E Kagan 《Biulleten' eksperimental'no? biologii i meditsiny》1986,102(7):25-28
Changes in potential-dependent fluorescence were studied, using fluorescent probe di-S-C3-(5), in synaptosome suspensions exposed to phospholipase A2, alpha-tocopherol and its derivatives. Phospholipase A2 increased potential-dependent fluorescence, i.e. depolarization of synaptosome membranes. The damaging phospholipase A2 effect was prevented and/or abolished by alpha-tocopherol added to synaptosome suspensions before and after phospholipase A2. Alpha-tocopherol derivatives (2,2,5,7,8-pentamethyl-6-hydroxychromane and alpha-tocopheryl-acetate as well as 4-methyl-2,6-di-tert-butylphenol) failed to exert a protective effect on synaptosome membranes modified by phospholipase A2. It is suggested that alpha-tocopherol effect is determined by its interaction with fatty acids, with 6-hydroxy groups of chromanol nucleus and phytol chain being essential for the complex formation. 相似文献