全文获取类型
收费全文 | 394481篇 |
免费 | 45391篇 |
国内免费 | 360篇 |
专业分类
440232篇 |
出版年
2016年 | 3565篇 |
2015年 | 5340篇 |
2014年 | 6231篇 |
2013年 | 8955篇 |
2012年 | 9934篇 |
2011年 | 10002篇 |
2010年 | 6657篇 |
2009年 | 6288篇 |
2008年 | 8899篇 |
2007年 | 9383篇 |
2006年 | 8923篇 |
2005年 | 8681篇 |
2004年 | 8611篇 |
2003年 | 8209篇 |
2002年 | 8202篇 |
2001年 | 18197篇 |
2000年 | 18751篇 |
1999年 | 14889篇 |
1998年 | 4898篇 |
1997年 | 5159篇 |
1996年 | 4808篇 |
1995年 | 4612篇 |
1994年 | 4547篇 |
1993年 | 4550篇 |
1992年 | 12056篇 |
1991年 | 11641篇 |
1990年 | 11302篇 |
1989年 | 10957篇 |
1988年 | 10342篇 |
1987年 | 9865篇 |
1986年 | 9371篇 |
1985年 | 9458篇 |
1984年 | 7812篇 |
1983年 | 6719篇 |
1982年 | 5347篇 |
1981年 | 4979篇 |
1980年 | 4520篇 |
1979年 | 7626篇 |
1978年 | 6155篇 |
1977年 | 5654篇 |
1976年 | 5339篇 |
1975年 | 5996篇 |
1974年 | 6626篇 |
1973年 | 6569篇 |
1972年 | 6086篇 |
1971年 | 5509篇 |
1970年 | 4757篇 |
1969年 | 4718篇 |
1968年 | 4300篇 |
1967年 | 3616篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
Altitude-induced alterations in drug action and metabolism 总被引:2,自引:0,他引:2
972.
A cholinergic proteolipid fraction (i.e. a hydrophobic lipoprotein) was separated from the of the cow, using affinity chromatography with the lipophilic gel Sephadex LH-20 and p-phenyltrimethylamonium as the active group. High affinity binding studies showed that only the specific fraction, desorbed after an acetylcholine (or acid) pulse, and corresponding to 0,72% of the proteolipids, is the one that binds the cholinergic ligands. The binding of (3H)atropine and (14C)d-tubocurarine demonstrated that there are 814 picomoles/g fresh tissue of muscarinic sites and only 76 picomoles/g of nicotinic sites. The specific radioactivity for (3H)atropine is 10,000 nmoles/g protein, suggesting a high degree of purification of the specific cholinergic proteolipid. 相似文献
973.
974.
Autolytic enzyme system from Lactobacillus fermenti 总被引:2,自引:0,他引:2
975.
976.
24 patients with non-Hodgkin's lymphomas of low-grade malignancy (stage III and IV) were treated either with a single drug (prednimustine) or with combination chemotherapy (cyclophosphamide, vincristine and prednisone). Response to therapy was similar in both groups. Prednimustine induced complete remission in 6 from 13 patients, while in that group treated with combination chemotherapy a complete remission was recorded in 4 from 11 patients. Both regimens were well tolerated. Therapy with prednimustin has an advantage in oral administration enabling it to be used in out-patient practice. 相似文献
977.
Binding experiments using [14C]GTP and rat liver rough microsomes gave Scatchard plots with Kd congruent to 0.1 microM and a binding capacity congruent to 40 pmol/mg microsomal protein. Removal of the ribosomes did not modify the binding parameters. GTP was competed out by GTP analogues but not by ATP. Limited proteolysis of rough microsomes decreased the GTP-binding capacity and prevented GTP from suppressing the latency of mannose-6-phosphatase and of the synthesis of dolichol-linked chitobiose. The GTP-binding protein is probably involved in these effects of GTP. Its function could be to act in the association-dissociation of membrane components at the ribosome-membrane junction. 相似文献
978.
979.
980.
Developmental regulation of myelin basic protein expression in mouse brain has been examined by comparing the myelin basic protein coding potential of mRNA in vitro with the accumulation of myelin basic protein-related polypeptides in vivo. In vitro translation of mRNA isolated from mouse brain generated eight myelin basic protein-related polypeptides with apparent molecular weights of 34K, 30K, 29K, 26K, 21.5K, 18.5K, 17K, and 14K. A similar set of eight myelin basic protein-related polypeptides with corresponding molecular weights was identified in vivo when total brain proteins were analyzed by immunoblotting. Each of the myelin basic protein-related polypeptides shows a characteristic developmental profile in terms of mRNA level and rate of accumulation implying a complex developmental program of myelin basic protein gene expression with regulation and modulation at several different biosynthetic levels. 相似文献