全文获取类型
收费全文 | 476488篇 |
免费 | 43343篇 |
国内免费 | 295篇 |
出版年
2018年 | 5097篇 |
2017年 | 4897篇 |
2016年 | 6384篇 |
2015年 | 7160篇 |
2014年 | 8835篇 |
2013年 | 13023篇 |
2012年 | 14694篇 |
2011年 | 15398篇 |
2010年 | 10618篇 |
2009年 | 9422篇 |
2008年 | 13825篇 |
2007年 | 14261篇 |
2006年 | 13625篇 |
2005年 | 12977篇 |
2004年 | 12935篇 |
2003年 | 12505篇 |
2002年 | 12276篇 |
2001年 | 19753篇 |
2000年 | 19544篇 |
1999年 | 15350篇 |
1998年 | 5286篇 |
1997年 | 5328篇 |
1996年 | 5100篇 |
1995年 | 4577篇 |
1994年 | 4535篇 |
1992年 | 12633篇 |
1991年 | 12846篇 |
1990年 | 12502篇 |
1989年 | 12407篇 |
1988年 | 11456篇 |
1987年 | 10909篇 |
1986年 | 9997篇 |
1985年 | 10385篇 |
1984年 | 8467篇 |
1983年 | 7067篇 |
1982年 | 5188篇 |
1981年 | 4701篇 |
1980年 | 4511篇 |
1979年 | 7977篇 |
1978年 | 6168篇 |
1977年 | 5883篇 |
1976年 | 5546篇 |
1975年 | 6350篇 |
1974年 | 7014篇 |
1973年 | 6882篇 |
1972年 | 6142篇 |
1971年 | 5805篇 |
1970年 | 5103篇 |
1969年 | 4984篇 |
1968年 | 4584篇 |
排序方式: 共有10000条查询结果,搜索用时 531 毫秒
941.
The phosphorylation of the membrane skeleton components protein 4.1 and protein 4.9 in intact erythrocytes is shown to increase in the presence of either 1 microM 12-O-tetradecanoyl phorbol 13-acetate or 2 mM dibutyryl cAMP. The phosphorylation induced by these protein kinase activators is compared by two-dimensional tryptic peptide mapping. In both proteins, the pattern of peptides phosphorylated in the presence of 12-O-tetradecanoyl phorbol 13-acetate differs from the pattern of peptides phosphorylated in the presence of dibutyryl cAMP. The relative locations of the phosphorylated sites on protein 4.1 have been determined using limited proteolysis by alpha-chymotrypsin. 相似文献
942.
A A Krichevskaia A I Lukash N V Pushkina I V Shepotinovskaia K B Sherstnev 《Nauchnye doklady vysshe? shkoly. Biologicheskie nauki》1984,(7):23-28
The amide content of total proteins and protein fractions (alpha-, beta-, gamma-cristallins and albuminoid) from cortex and nuclear lens zones of cattle has been investigated. The amide content in proteins of cortex and nuclear lens of young animals (1,5-2 years old) is the same. The decrease of the amide content in the proteins of nuclear lenz zone of old animals (6-12 years old) is due to fraction of readily hydrolysed amides. The data obtained prove the posttranslational desamidation of lens proteins at ageing. beta-Cristallines--the proteins with the highest amides content is exposed to posttranslational desamidation most of all. 相似文献
943.
944.
The stoichiometric palmitoyllysophosphatidylcholine (lysoPC)/gramicidin (4:1, mol/mol) lamellar complex (Killian, J.A., De Kruijff, B., Van Echteld, C.J.A., Verkleij, A.J., Leunissen-Bijvelt, J. and De Gier, J. (1983) Biochim. Biophys. Acta 728, 141-144) is a useful model system to investigate the various aspects of lipid protein interactions. To study the effect of gramicidin on local order and motion of 1-palmitoyl-sn-glycero-3-phosphocholine (lysoPC) we employed 31P and 2H nuclear magnetic resonance (NMR) using selectively deuterated lysoPC's and we compared the results to those obtained for lysoPC in bilayers with cholesterol (1:1, mol/mol) and dipalmitoylphosphatidylcholine (DPPC) (1:4, mol/mol). 2H-NMR experiments on acyl chain deuterated lysoPC showed similar quadrupole splittings in the liquid crystalline state for the lysoPC/DPPC and the lysoPC/gramicidin samples. In the lysoPC/cholesterol sample an increase of the quadrupole splitting was found. T1 measurements showed that gramicidin decreases the lysoPC acyl chain motion, especially at the C12 position. In the lysoPC/cholesterol sample an increase of motion was observed as compared to lysoPC in fluid bilayers of DPPC. 31P-NMR and 2-H-NMR measurements of lysoPC, deuterated at the alpha- and beta-position of the choline moiety, indicated an increase in headgroup flexibility in all samples as compared to the parent compound DPPC. In addition, a change in headgroup conformation was observed. The alpha- and beta-segments in all samples exhibited concerted motion. It was found that also in the polar headgroup gramicidin induces a decrease of the rate of motion. 相似文献
945.
946.
Plasma choline concentrations were measured in humans, rats, and rabbits within the first few hours of life, before any food was ingested. Neonatal animals and humans had markedly elevated plasma choline levels compared to adult animals or humans. Possible mechanisms responsible for this elevation are discussed and possible consequences for brain function, lung function, and growth are presented. 相似文献
947.
F. -W. Bentrup 《European biophysics journal : EBJ》1980,6(3):175-189
This review treats some examples of electrogenic transport across the outer plasmamembrane (plasmalemma) of plant cells. The selection includes primary active uniport by membrane ATPases (e.g., the proton pump), secondary active transport of hexoses by proton-dependent cotransport, and passive uniport of amines. Primacy is given to the presentation of electrophysiological data and to the discussion of voltage-dependence of the transport mechanisms.Lecture from the Annual Meeting of the Deutsche Gesellschaft für Biophysik at Konstanz 相似文献
948.
949.
950.
A. V. Andriyash D. A. Vikhlyaev D. A. Dmitrov A. L. Zapysov A. G. Kakshin I. A. Kapustin E. A. Loboda V. A. Lykov A. V. Potapov V. A. Pronin V. N. Sanzhin V. N. Saprykin A. A. Ugodenko O. V. Chefonov M. N. Chizhkov 《Plasma Physics Reports》2006,32(2):135-137
Results are presented from experimental investigations of the angular distributions and energy spectra of fast ions produced in deuterium polyethylene targets under irradiation by picosecond laser pulses with intensities of up to 2 × 1018 W/cm2 in the SOKOL-P facility. The parameters of ion fluxes were measured by time-of-flight spectrometers based on semiconductor detectors. 相似文献