全文获取类型
收费全文 | 40268篇 |
免费 | 3956篇 |
国内免费 | 31篇 |
专业分类
44255篇 |
出版年
2018年 | 407篇 |
2016年 | 513篇 |
2015年 | 568篇 |
2014年 | 728篇 |
2013年 | 1092篇 |
2012年 | 1040篇 |
2011年 | 1116篇 |
2010年 | 754篇 |
2009年 | 607篇 |
2008年 | 875篇 |
2007年 | 956篇 |
2006年 | 926篇 |
2005年 | 902篇 |
2004年 | 861篇 |
2003年 | 929篇 |
2002年 | 901篇 |
2001年 | 2123篇 |
2000年 | 2046篇 |
1999年 | 1609篇 |
1998年 | 555篇 |
1997年 | 501篇 |
1996年 | 509篇 |
1995年 | 453篇 |
1994年 | 449篇 |
1993年 | 451篇 |
1992年 | 1297篇 |
1991年 | 1298篇 |
1990年 | 1239篇 |
1989年 | 1236篇 |
1988年 | 1188篇 |
1987年 | 1132篇 |
1986年 | 980篇 |
1985年 | 982篇 |
1984年 | 776篇 |
1983年 | 666篇 |
1982年 | 442篇 |
1981年 | 407篇 |
1980年 | 411篇 |
1979年 | 787篇 |
1978年 | 598篇 |
1977年 | 545篇 |
1976年 | 469篇 |
1975年 | 620篇 |
1974年 | 728篇 |
1973年 | 670篇 |
1972年 | 641篇 |
1971年 | 551篇 |
1970年 | 513篇 |
1969年 | 485篇 |
1968年 | 409篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
G Dumoulin N U Nguyen M T Henriet J Bopp S Berthelay 《Comptes rendus des séances de la Société de biologie et de ses filiales》1980,174(2):146-150
Plasma Na, K, Cl, Ca, P didn't or moderately be altered by exposure to acute heat in sauna bath (20 mn, 80 degrees C, relative humidity 15-20%). However, CO2T decreased, ARP, aldosterone, ACTH, PRL increased, and PTH wasn't modified. 相似文献
82.
In this study it is shown that the higher molecular weight previously reported for tiger shark carbonic anhydrase (carbonate hydro-lyase, EC 4.2.1.1) compared to other carbonic anhydrases is decreased to a normal value around 30 000 after disulfide reduction of the enzyme. This difference in molecular weight is at least partly due to the existence of disulfide-linked glutathione and cysteine residues. Approx. 3 mol glutathione and a similar amount of cysteine are shown to be bound per mol enzyme. The presence of these factors also has effects on the enzyme activity. 相似文献
83.
84.
A robust method for selection of variables with the greatest discriminatory power is presented in the paper. The method deals with the two groups of data problem. An application of the method to some respiratory disease data and comparisons with classical procedures are given, also. 相似文献
85.
86.
Platinum(II) binding to metallothioneins 总被引:1,自引:0,他引:1
The reaction of equine renal metallothionein (MT) with excess K2PtCl4 at pH 2 results in a polymeric adduct containing 17 +/- 2 mol Pt/mol MT. A monomeric adduct containing 7 mol Pt/mol MT is obtained at neutral pH. Rates of reaction of Pt7MT with DTNB and iodoacetic acid are consistent with Pt2+ to cysteine thiolate coordination, and the extent of reaction in both cases is 11 +/- 2 mol cys/mol MT. Adducts from the reaction of K2PtCl4 with apoMT chemically modified at the N-terminal methionine residue, Cd7MT, and native MT are also reported. A structural model of Pt7MT is proposed in which the square planar tetrathiolate Pt(II) unit is incorporated into a three-metal beta cluster. Implications for the metabolism of platinum anticancer drugs are discussed. 相似文献
87.
W Tymiński E Czestochowska A Hellmann A Kreglewski 《Folia haematologica (Leipzig, Germany : 1928)》1980,107(2):269-272
Coagulation and fibrinolysis were measured in the portal and peripheral circulation in 15 rabbits after ligation of the superior mesenteric artery. It was found that the local coagulation syndrome in the mesenteric region can be recognized by tests in blood samples taken from the peripheral circulation area. 相似文献
88.
The influence of orotic acid on post-excitatory facilitation of evoked potentials released by electric stimulation of the tooth pulp in the sensomotor cortex was studied. 15-360 min following application of 100 mg/kg orotic acid, increase in amplitude of potentials released by stimulation of the tooth pulp, reinforcement of the post-excitatory facilitation observable 5 msec after stimulation occurred. 相似文献
89.
The properties of the pH 4.0 endonuclease from adenovirus-type-2-infected KB cells were determined. The enzyme has a molecular weight of approximately 40000. Its pH optimum is at pH 4.0, it is not inhibited by ethylenediaminetetraacetate (EDTA), and it is active at temperatures up to 60 degree C. The enzyme cleaves adenovirus DNA in a stepwise manner. The limit digestion product has a molecular weight of 120000-200000. There is evidence that the cleavage reaction proceeds via an initial single-strand nick. Under the conditions tested the endonuclease did not seem to reveal a high degree of specificity as to the recognition of cleavage sites, or else the sites recognized occurred very frequently. 相似文献
90.