全文获取类型
收费全文 | 5878篇 |
免费 | 385篇 |
国内免费 | 3篇 |
出版年
2021年 | 55篇 |
2020年 | 28篇 |
2019年 | 38篇 |
2018年 | 68篇 |
2017年 | 64篇 |
2016年 | 89篇 |
2015年 | 156篇 |
2014年 | 176篇 |
2013年 | 221篇 |
2012年 | 271篇 |
2011年 | 269篇 |
2010年 | 174篇 |
2009年 | 161篇 |
2008年 | 284篇 |
2007年 | 279篇 |
2006年 | 275篇 |
2005年 | 282篇 |
2004年 | 270篇 |
2003年 | 243篇 |
2002年 | 206篇 |
2001年 | 216篇 |
2000年 | 234篇 |
1999年 | 203篇 |
1998年 | 69篇 |
1997年 | 74篇 |
1996年 | 53篇 |
1995年 | 64篇 |
1994年 | 34篇 |
1993年 | 72篇 |
1992年 | 166篇 |
1991年 | 147篇 |
1990年 | 121篇 |
1989年 | 130篇 |
1988年 | 136篇 |
1987年 | 86篇 |
1986年 | 83篇 |
1985年 | 92篇 |
1984年 | 80篇 |
1983年 | 68篇 |
1982年 | 46篇 |
1981年 | 43篇 |
1980年 | 26篇 |
1979年 | 43篇 |
1978年 | 39篇 |
1977年 | 35篇 |
1976年 | 26篇 |
1975年 | 43篇 |
1974年 | 45篇 |
1973年 | 39篇 |
1968年 | 23篇 |
排序方式: 共有6266条查询结果,搜索用时 781 毫秒
991.
Characteristics of rabbit ClC-2 current expressed in Xenopus oocytes and its contribution to volume regulation 总被引:4,自引:0,他引:4
Furukawa Tetsushi; Ogura Takehiko; Katayama Yoshifumi; Hiraoka Masayasu 《American journal of physiology. Cell physiology》1998,274(2):C500
In theXenopus oocyte heterologous expressionsystem, the electrophysiological characteristics of rabbit ClC-2current and its contribution to volume regulation were examined.Expressed currents on oocytes were recorded with a two-electrodevoltage-clamp technique. Oocyte volume was assessed by taking picturesof oocytes with a magnification of ×40. Rabbit ClC-2 currentsexhibited inward rectification and had a halide anion permeabilitysequence of Cl Br I F. ClC-2 currents wereinhibited by 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB),diphenylamine-2-carboxylic acid (DPC), and anthracene-9-carboxylic acid(9-AC), with a potency order of NPPB > DPC = 9-AC, but were resistant to stilbene disulfonates. These characteristics are similarto those of rat ClC-2, suggesting rabbit ClC-2 as a counterpart of ratClC-2. During a 30-min perfusion with hyposmolar solution, currentamplitude at 160 mV and oocyte diameter were compared amongthree groups: oocytes injected with distilled water, oocytes injectedwith ClC-2 cRNA, and oocytes injected with ClC-2NT cRNA (an openchannel mutant with NH2-terminaltruncation). Maximum inward current was largest in ClC-2NT-injectedoocytes (5.9 ± 0.4 µA), followed by ClC-2-injected oocytes(4.3 ± 0.6 µA), and smallest in water-injected oocytes(0.2 ± 0.2 µA), whereas the order of increase in oocytediameter was as follows: water-injected oocytes (9.0 ± 0.2%) > ClC-2-injected oocytes (5.3 ± 0.5%) > ClC-2NT-injected oocytes (1.1 ± 0.2%). The findings that oocyte swelling wassmallest in oocytes with the largest expressed currents suggest thatClC-2 currents expressed in Xenopusoocytes appear to act for volume regulation when exposed to ahyposmolar environment. 相似文献
992.
993.
994.
1. Localization of carbon in caffeine molecule biosynthesizedfrom the N-methyl carbon of -glutamylmethylamide in tea plantswas observed. 14C-Caffeine produced from 14C--glutamylmethylamidewas isolated and degraded. Approximately 2655% of the14C was observed in the three methyl carbons in caffeine, withonly 23% at the C-2 carbon, 37% at the C-8 carbonposition. The amount of 14C at the C-4, C-5 and C-6 positionswas calculated from the results obtained. 2. The role of the N-methyl carbon of -glutamylmethylamide inthe formation of RNA in tea plants was examined. Incorporationof the N-methyl-14C of 14C--glutamylmethylamide into AMP andGMP in RNA was found. These facts indicate that in tea plants, -glutamylmethylamideis metabolized and most of its N-methyl carbon is utilized asa precursor for caffeine formation and little, if any, as aprecursor for nucleic acid formation.
1 Present address: Department of Agricultural Chemistry, ShizuokaUniversity, Iwata, Shizuoka 438, Japan. (Received February 2, 1972; ) 相似文献
995.
The mechanism of the lytic action of prymnesin, a toxin produced by the alga, Prymnesium parvum, was studied using liposomes as a model membrane system. Prymnesin showed severe damage to liposomes containing cholesterol but did not affect those without cholesterol. The requirement of cholesterol for the susceptibility to prymnesin was much more strict than the reported requirement for the susceptibility to polyene antibiotics. The net charge on the membranes was shown not to be important for the reaction. 相似文献
996.
Phospholipase A-deficient mutants of Escherichia coli B 总被引:1,自引:0,他引:1
Phospholipase A-deficient mutants were isolated from Escherichia coli B/SM as follows. Replica plates were incubated to allow formation of colonies and then overlayed with soft agar containing washed sheep erythrocytes, lecithin Ca++, colistin, lysozyme and streptomycin. The mutant colonies were detected as colonies without hemolytic zones. Two or three cycles of treatment with mutagen and selection were necessary for their isolation. The mutants obtained could grow in a synthetic medium with glucose as the sole carbon source, and their phospholipid compositions were similar to that of the parent. They also gave the same agglutination titer as the parent with rabbit antiserum against the parent strain. They supported the growth of all members of the T-series of bacteriophages as effectively as the parent. Some hemolytic substance was produced from either lecithin or bacterial constituents when the mutants were infected with T even phages, but not with T odd phages. When the parent strain was infected with either T1 or T4, free fatty acids (FFA) were produced in the cell debris. Only a trace of FFA was formed in the debris of one of these mutants on infection with T4 and no FFA was formed on infection with T1. 相似文献
997.
Solubility properties of the murine zona pellucida 总被引:1,自引:0,他引:1
998.
999.
1000.