全文获取类型
收费全文 | 635203篇 |
免费 | 61047篇 |
国内免费 | 219篇 |
专业分类
696469篇 |
出版年
2018年 | 7558篇 |
2017年 | 7287篇 |
2016年 | 9552篇 |
2015年 | 11434篇 |
2014年 | 13374篇 |
2013年 | 19426篇 |
2012年 | 22229篇 |
2011年 | 22465篇 |
2010年 | 15144篇 |
2009年 | 13384篇 |
2008年 | 19634篇 |
2007年 | 19977篇 |
2006年 | 19158篇 |
2005年 | 17891篇 |
2004年 | 17775篇 |
2003年 | 16993篇 |
2002年 | 16530篇 |
2001年 | 26780篇 |
2000年 | 26696篇 |
1999年 | 21365篇 |
1998年 | 7417篇 |
1997年 | 7498篇 |
1996年 | 7210篇 |
1995年 | 6543篇 |
1994年 | 6565篇 |
1993年 | 6368篇 |
1992年 | 17451篇 |
1991年 | 17053篇 |
1990年 | 16883篇 |
1989年 | 16869篇 |
1988年 | 15473篇 |
1987年 | 14659篇 |
1986年 | 13572篇 |
1985年 | 13814篇 |
1984年 | 11237篇 |
1983年 | 9540篇 |
1982年 | 7079篇 |
1981年 | 6208篇 |
1980年 | 6033篇 |
1979年 | 10478篇 |
1978年 | 8156篇 |
1977年 | 7344篇 |
1976年 | 7113篇 |
1975年 | 7974篇 |
1974年 | 8528篇 |
1973年 | 8427篇 |
1972年 | 7600篇 |
1971年 | 6825篇 |
1970年 | 5999篇 |
1969年 | 5680篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
The interaction between human plasma lipoproteins and connective tissue glycosaminoglycans 总被引:29,自引:0,他引:29
P H Iverius 《The Journal of biological chemistry》1972,247(8):2607-2613
992.
993.
G V Kolusheva 《Arkhiv anatomii, gistologii i émbriologii》1987,93(7):10-15
The electron microscopic method has revealed early maturation of the protein-synthesizing apparatus of some cells, on the one hand, and underdevelopment of neuroblast volumes, appearance of artificial contacts, axonal degeneration and destruction in large trunks, on the other hand. Compensatory-restorative processes in the cell on the 14th and 21st days of the postnatal development result in a complete restoration of morphological organization of neurons and interneuronal connections in the hypothalamus of offspring of the morphine-dependent rats. 相似文献
994.
Density gradient analysis of newly replicated DNA from synchronized mouse lymphoma cells 总被引:3,自引:0,他引:3
The replication of DNA in synchronous cultures of mouse lymphoma cells was investigated by use of CsCl density gradient centrifugation. We found that the buoyant density of newly replicated DNA depended upon the particular stage of S phase in which synthesis occurred. In early S phase, newly replicated DNA exhibited buoyant densities which were slightly higher, on the average, than that of pre-existing DNA. As S phase progressed, newly replicated DNA shifted to lower buoyant densities, until, near the end of S phase, densities less than pre-existing DNA were observed. These observations are discussed in terms of their possible relevance to base compositional differences between nucleotide sequences made in early as opposed to middle or late S phase. 相似文献
995.
M R Kopantseva M Z Liudvig I I Uspenski? N A Tamarina V A Tsatrian L I Korochkin 《Zhurnal obshche? biologii》1990,51(1):125-140
A comparative electrophoretic study or ejaculatory bulb proteins in 29 different Drosophila species has been carried out. In all analyzed species, ejaculatory bulb contains a major component (designated as PEB). It has molecular mass of 61-65 kDa in the species of virilis group, 33-36 kDa in species of obscura group, and 34-56 kDa in species of melanogaster group. Using immunoblotting technique, we have demonstrated that PEB is introduced into organs of female sex tract during mating. The nature and significance of revealed interspecific differences in PEB proteins has been discussed. 相似文献
996.
When the roots of Vicia faba L. beans were subjected to hypoxic stress, the activity of H+-ATPase on the peribacteroid membrane, as well as the transport of dicarboxylates (malate and succinate) mediated by this
enzyme, decreased. Since malate and succinate are the main carbon-containing metabolites involved in the energy supply to
bacteroids, this caused a change of the relation type from mutualism to commensalism, and the domination of the eukaryotes
over the prokaryotes consequently increased. 相似文献
997.
SUMMARY: MIAH is a WWW server for the automatic alignment of new eukaryotic SSU rRNA sequences to an existing alignment of 1500 sequences. AVAILABILITY: http://chah.ucc.ie/MIAH Contact : 相似文献
998.
K P Ivanov N A Slepchuk 《Rossi?skii fiziologicheski? zhurnal imeni I.M. Sechenova / Rossi?skaia akademiia nauk》1999,85(5):680-689
The brain temperature, at which the cessation of the lung respiration occurs in the cooled animals, can be named the lower temperature limit of the brain functional competence, since at this temperature the spontaneous respiration is not restored on its own, and without special artificial undertakings the animals perish. In this study upon the total cooling of the rat bodies their lung respiration stopped completely as the temperature of the medulla oblongata in the region of the respiratory center decreased to 18.18 +/- 0.17 degrees C. This occurred simultaneously with an abrupt decrease in the heart rate and in the arterial blood pressure (AP) to 42 +/- 1 mm Hg. Upon an isolated cooling of the rat head the heart rate and AP were maintained at a comparatively high level. Under such conditions the lung respiration did not stop even as the temperature of the medulla oblongata decreased to 17.23 +/- 0.25 degrees C. It retained rhythmicallity, a particular rate, and a comparatively high amplitude. It is suggested that an intensive blood supply of the cooled brain decreases the lower temperature limit of its vital activity. 相似文献
999.
M. A. P. J. Hacking F. van Rantwijk R. A. Sheldon 《Journal of Molecular Catalysis .B, Enzymatic》2000,9(4-6):201-208
Symmetrical dialkyl carbonates and dibenzyl carbonates reacted with various nucleophiles in the presence of Candida antarctica lipase B in organic solvents. For example, reaction of dibutyl and dibenzyl carbonate with an alcohol gave a mixture of the mono- and disubstituted products. Aminolysis, however, afforded only the carbamates, without subsequent reaction to the ureum derivatives. The reaction rates were rather low compared with carboxylic esters; the reactivity increased in the order dimethyl相似文献
1000.
A M Belles T J Montville B P Wasserman 《Journal of industrial microbiology & biotechnology》2000,24(1):71-74
Alcohol-extractable, hydrophobic zein proteins contaminate starch granule surfaces and can be removed by enzymatic digestion
with thermolysin. The goal of this research was to find practical alternatives to thermolysin that might be used during the
corn wet-milling process. All of the commercial thermostable alkaline proteases studied (SP 709, Neutrase, and Spezyme FAN)
removed the zein proteins from various types of cornstarch, as demonstrated by the lack of protein bands below 30 kDa under
the reducing conditions of SDS-PAGE gel. Each enzyme removed the zein proteins as effectively as thermolysin removed them.
However, the removal of the zein protein did not reduce the quantity of free fatty acids associated with the starch. Journal of Industrial Microbiology & Biotechnology (2000) 24, 71–74.
Received 27 May 1999/ Accepted in revised form 01 October 1999 相似文献