全文获取类型
收费全文 | 769482篇 |
免费 | 93212篇 |
国内免费 | 290篇 |
出版年
2016年 | 8515篇 |
2015年 | 11852篇 |
2014年 | 14062篇 |
2013年 | 20142篇 |
2012年 | 22269篇 |
2011年 | 22595篇 |
2010年 | 15066篇 |
2009年 | 14007篇 |
2008年 | 20004篇 |
2007年 | 21132篇 |
2006年 | 19659篇 |
2005年 | 19141篇 |
2004年 | 19119篇 |
2003年 | 18444篇 |
2002年 | 17926篇 |
2001年 | 32701篇 |
2000年 | 33114篇 |
1999年 | 26658篇 |
1998年 | 9689篇 |
1997年 | 10102篇 |
1996年 | 9687篇 |
1995年 | 9372篇 |
1994年 | 9378篇 |
1993年 | 9183篇 |
1992年 | 23203篇 |
1991年 | 22807篇 |
1990年 | 22435篇 |
1989年 | 21693篇 |
1988年 | 20401篇 |
1987年 | 19474篇 |
1986年 | 18179篇 |
1985年 | 18413篇 |
1984年 | 15364篇 |
1983年 | 13541篇 |
1982年 | 10569篇 |
1981年 | 9730篇 |
1980年 | 9191篇 |
1979年 | 15459篇 |
1978年 | 11917篇 |
1977年 | 11034篇 |
1976年 | 10456篇 |
1975年 | 11515篇 |
1974年 | 12169篇 |
1973年 | 12122篇 |
1972年 | 11324篇 |
1971年 | 10131篇 |
1970年 | 8761篇 |
1969年 | 8373篇 |
1968年 | 7545篇 |
1967年 | 6613篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
901.
O. V. Yagodina E. B. Nikol’skaya I. Y. Shemarova A. E. Khovanskikh 《Journal of Evolutionary Biochemistry and Physiology》2000,36(3):244-248
A comparison has been performed of catalytic properties of unicellular microorganism amine oxidases (AO) from two new enzyme
sources, the bacteriumMethanosarcina barkeri and the infusoriaTetrahymena pyriformis. It was shown that the both studied AO deaminate tyramine, serotonin, and benzylamine, but do not deaminate histamine. The
AO fromMethanosarcina barkeri catalyzes deamination of all three substrates at an identical rate, while the rate of tyramine deamination under effect of
AO fromTetrahymena pyriformis is one order higher than the rate of serotonin deamination, and about two orders higher than the rate of benzylamine deamination.
Based on the data of the substrate-inhibitor analysis, a suggestion was made about the existence of one center for the substrate
binding in the AO of the studied bacterium, while several centers in the AO of the studied infusoria. 相似文献
902.
903.
904.
905.
Brunner RM Srikanchai T Murani E Wimmers K Ponsuksili S 《Molecular biology reports》2012,39(1):97-107
Six genes that were known to exhibit expression levels that are correlated to drip loss BVES, SLC3A2, ZDHHC5, CS, COQ9, and
EGFR have been for candidate gene analysis. Based on in silico analysis SNPs were detected, confirmed by sequencing, and used for genotyping. The SNPs were genotyped in about 1,800 animals
from six pig populations including commercial herds of Pietrain (PI) and German Landrace (DL), different commercial herds
of Pietrain × (German Large White × German Landrace) (PIF1(a/b/c)), and one experimental F2-population Duroc × Pietrain (DUPI). Comparative and genetic mapping established the location of BVES on SSC1, of SLC3A2 and
ZDHHC5 on SSC2, of CS on SSC5, of COQ9 on SSC6 and of EGFR on SSC9, respectively, coinciding with QTL regions for carcass
and meat quality traits. BVES, SLC3A2, and CS revealed association at least with drip loss and with several other measures
of water holding capacity (WHC). Moreover, COQ9 and EGFR were associated with several meat quality traits such as meat color
and/or thawing loss. This study reveals statistic evidence in addition to the functional relationship of these genes to WHC
previously evidenced by expression analysis. This study reveals positional and genetic statistical evidence for a link of
genetic variation at these loci or close to them and promotes those six candidate genes as functional and/or positional candidate
genes for meat quality traits. 相似文献
906.
907.
Shashank Hambarde Chi-Lin Tsai Raj K. Pandita Albino Bacolla Anirban Maitra Vijay Charaka Clayton R. Hunt Rakesh Kumar Oliver Limbo Remy Le Meur Walter J. Chazin Susan E. Tsutakawa Paul Russell Katharina Schlacher Tej K. Pandita John A. Tainer 《Molecular cell》2021,81(14):2989-3006.e9
- Download : Download high-res image (222KB)
- Download : Download full-size image
908.
F. D. Miller K. F. Jorgenson R. J. Winkfein J. H. van de Sande D. A. Zarling J. Stockton 《Journal of biomolecular structure & dynamics》2013,31(3):611-620
Abstract Bacteriophage PM2 DNA, a ccc genome of high apparent superhelical density, contains left-handed (Z) regions as detected by competitive radioimmunoassay, agarose gel electrophoresis of DNA: antibody complexes and immunoelectron microscopy. The latter technique, in conjunction with partial blockage of restriction endonuclease sites by bound antibody, was used to map the left-handed regions along the DNA molecule. A cluster of four to five antibody molecules (approximately 25% of bound antibody) was located within map units 0.05–0.18 of the single Hpa II restriction site. Sequence analysis of part of this region showed the presence of several areas of high alternating purine-pyrimidine content. A strong correlation is observed between alternating pyrimidine-purine tracts of significant length and antibody binding sites. 相似文献
909.
Michael R. Seringhaus 《The Yale journal of biology and medicine》2002,75(4):239-Aug;75(4):239
910.
In order to adapt to the fluctuations in soil salinity/osmolarity the bacteria of the genusAzospirillum accumulate compatible solutes such as glutamate, proline, glycine betaine, trehalose, etc. Proline seems to play a major
role in osmoadaptation. With increase in osmotic stress the dominant osmolyte inA. brasilense shifts from glutamate to proline. Accumulation of proline inA. brasilense occurs by both uptake and synthesis. At higher osmolarityA. brasilense Sp7 accumulates high intracellular concentration of glycine betaine which is taken up via a high affinity glycine betaine
transport system. A salinity stress induced, periplasmically located, glycine betaine binding protein (GBBP) of ca. 32 kDa
size is involved in glycine betaine uptake inA. brasilense Sp7. Although a similar protein is also present inA. brasilense Cd it does not help in osmoprotection. It is not known ifA. brasilense Cd can also accumulate glycine betaine under salinity stress and if the GBBP-like protein plays any role in glycine betaine
uptake. This strain, under salt stress, seems to have inadequate levels of ATP to support growth and glycine betaine uptake
simultaneously. ExceptA. halopraeferens, all other species ofAzospirillum lack the ability to convert choline into glycine betaine. Mobilization of thebet ABT genes ofE. coli intoA. brasilense enables it to use choline for osmoprotection. Recently, aproU-like locus fromA. lipoferum showing physical homology to theproU gene region ofE. coli has been cloned. Replacement of this locus, after inactivation by the insertion of kanamycin resistance gene cassette, inA. lipoferum genome results in the recovery of mutants which fail to use glycine betaine as osmoprotectant. 相似文献