全文获取类型
收费全文 | 841601篇 |
免费 | 104416篇 |
国内免费 | 354篇 |
出版年
2016年 | 9276篇 |
2015年 | 13152篇 |
2014年 | 15468篇 |
2013年 | 22200篇 |
2012年 | 24537篇 |
2011年 | 25073篇 |
2010年 | 16653篇 |
2009年 | 15619篇 |
2008年 | 22209篇 |
2007年 | 23107篇 |
2006年 | 21459篇 |
2005年 | 20965篇 |
2004年 | 20492篇 |
2003年 | 20109篇 |
2002年 | 19324篇 |
2001年 | 36304篇 |
2000年 | 36860篇 |
1999年 | 29475篇 |
1998年 | 10805篇 |
1997年 | 11517篇 |
1996年 | 10981篇 |
1995年 | 10458篇 |
1994年 | 10382篇 |
1993年 | 10350篇 |
1992年 | 25557篇 |
1991年 | 25246篇 |
1990年 | 24460篇 |
1989年 | 24021篇 |
1988年 | 22217篇 |
1987年 | 21489篇 |
1986年 | 20181篇 |
1985年 | 20307篇 |
1984年 | 17055篇 |
1983年 | 14974篇 |
1982年 | 11645篇 |
1981年 | 10658篇 |
1980年 | 10126篇 |
1979年 | 16825篇 |
1978年 | 13219篇 |
1977年 | 12181篇 |
1976年 | 11541篇 |
1975年 | 12729篇 |
1974年 | 13225篇 |
1973年 | 13063篇 |
1972年 | 12151篇 |
1971年 | 10810篇 |
1970年 | 9345篇 |
1969年 | 8884篇 |
1968年 | 8084篇 |
1967年 | 7104篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
952.
K Scheuch W D Pietruschka E Hentschel P Winiecki G Gruber 《Activitas nervosa superior》1988,30(3):169-173
Biochemical and immunological parameters, physical and mental performance, subjective complaints and behavioural characteristics were compared before and after 14 final examinations undertaken by 64 students during a three-month examination period. A decrease in cholesterol, triglycerides, HDL-cholesterol, physical performance and an increase in LDL/HDL cholesterol quotient, lactate level, mental performance were accompanied by a lower frequency of mental complaints and higher frequency of physical complaints. From the multidimensional variance and discriminant analysis 17 of the 44 variables discriminated between the state prior to and after the examination period. The results are interpreted in terms of the psychophysiological adaptation to adequate mental stress. 相似文献
953.
954.
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
955.
A. Klockow-Beck A. Nick St. Geisshuesler D. Schaufelberger 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1998,720(1-2):141-151
A capillary electrophoresis (CE) method has been developed as an alternative method for the determination of the inorganic degradation products sulfate and sulfamate in topiramate drug product and drug substance, currently performed by ion chromatography. The anions are separated in a background electrolyte containing potassium chromate and boric acid, followed by indirect UV detection. By adding tetradecyltrimethylammonium bromide to the electrolyte, analysis is performed under co-electroosmotic flow conditions. Variations in injection volumes and migration times are compensated for by use of an internal standard. The validation of the method, which was performed according to ICH guidelines (International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use) [1], comprises specificity, accuracy, linearity, precision, sensitivity and robustness. In addition, the results of an actual tablet sample analysis obtained by this CE method are statistically shown to be in close agreement with those obtained by an ion chromatographic method. 相似文献
956.
S. P. Kharitonov D. E. Nowak A. I. Nowak N. A. Egorova S. A. Korkina D. V. Osipov O. V. Natal’skaya 《Biology Bulletin》2009,36(5):469-478
Red-breasted goose colonies have been studied near Medusa Bay (73°21′N, 80°32′E), on the northwestern Taimyr Peninsula, and
along the Agapa River (70°11′N, 86°15′E) down to its mouth (71°26′N, 89° 13′E), in the central Taimyr Peninsula. Red-breasted
geese nesting near peregrine falcons are protected by the falcons from arctic foxes; however, they are sometimes attacked
by the falcons themselves. In the colonies near peregrine falcon nests, the vast majority of goose nests were situated no
farther than 100 m from the falcon nest. When food is abundant, falcons protect a larger area around their nest. The distance
between the falcon nest and the surrounding goose nests is inversely related to the falcon’s activity. In years of higher
falcon activity, falcons prevent red-breasted geese from nesting as close to their nest as in years of lower falcon activity.
Additional stimuli are required for red-breasted geese to form colonies near rough-legged buzzard nests. The distance between
snowy owl nests and red-breasted goose nests was smaller when arctic foxes were abundant than when they were scarce. 相似文献
957.
958.
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
959.
Michael R. Seringhaus 《The Yale journal of biology and medicine》2002,75(4):239-Aug;75(4):239
960.