全文获取类型
收费全文 | 6708篇 |
免费 | 603篇 |
国内免费 | 3篇 |
出版年
2023年 | 37篇 |
2022年 | 74篇 |
2021年 | 159篇 |
2020年 | 72篇 |
2019年 | 123篇 |
2018年 | 139篇 |
2017年 | 113篇 |
2016年 | 197篇 |
2015年 | 341篇 |
2014年 | 437篇 |
2013年 | 534篇 |
2012年 | 578篇 |
2011年 | 572篇 |
2010年 | 365篇 |
2009年 | 341篇 |
2008年 | 444篇 |
2007年 | 428篇 |
2006年 | 416篇 |
2005年 | 386篇 |
2004年 | 341篇 |
2003年 | 317篇 |
2002年 | 305篇 |
2001年 | 44篇 |
2000年 | 50篇 |
1999年 | 71篇 |
1998年 | 63篇 |
1997年 | 42篇 |
1996年 | 34篇 |
1995年 | 36篇 |
1994年 | 30篇 |
1993年 | 28篇 |
1992年 | 21篇 |
1991年 | 14篇 |
1990年 | 14篇 |
1989年 | 17篇 |
1988年 | 9篇 |
1987年 | 18篇 |
1986年 | 16篇 |
1985年 | 9篇 |
1983年 | 12篇 |
1981年 | 3篇 |
1980年 | 13篇 |
1979年 | 7篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1972年 | 2篇 |
1970年 | 2篇 |
1965年 | 2篇 |
排序方式: 共有7314条查询结果,搜索用时 15 毫秒
51.
Cuvillier Olivier; Alonso Catherine; Wieruszeski Jean-Michel; Brassart Colette; Strecker Gerard; Bouquelet Stephane; Michalski Jean-Claude 《Glycobiology》1995,5(3):281-289
During a systematic study of carbohydrate material present inhuman meconium, in addition to the previously described mucins,glycolipids and free oligosaccharides, we have now characterizeda significant quantity of free glycoasparagines. These glycoasparagineshave been isolated from human meconium by a combination of ion-exchange,concanavalin A (ConA)-affinity and high-performance liquid (HPLC)chromatographies. Their structures have been established by400 MHz 1H-NMR spectroscopy. These compounds are related toN-acetyllactosaminic type structures and are based on the commoncore These glycoasparagines are probably derived from both proteaseand partial exoglycosidase hydrolysis of fetal gastrointestinalN-glycosyl proteins. Their structures are discussed in the contextof the known catabolic pathways of N-glycans glycoasparagine N-glycosyl protein catabolism meconium NMR 相似文献
52.
Catherine Iehl Sylvie Dlos Olivier Guirou Rothwell Tate Jean-Pierre Raynaud Pierre-Marie Martin 《The Journal of steroid biochemistry and molecular biology》1995,54(5-6)
The present study describes the independent expression of the type 1 and 2 isoforms of human 5α-reductase in the baculovirus-directed insect cell expression system and the selectivity of their inhibition. The catalytic properties and kinetic parameters of the recombinant isozymes were consistent with published data. The type 1 isoform displayed a neutral (range 6–8) pH optimum and the type 2 isoform an acidic (5–6) pH optimum. The type 2 isoform had higher affinity for testosterone than did the type 1 isoform (Km = 0.5 and 2.9 μM, respectively). Finasteride and turosteride were selective inhibitors of the type 2 isoform (Ki (type 2) = 7.3 and 21.7 nM compared to Ki (type 1) = 108 and 330 nM, respectively). 4-MA and the lipido-sterol extract of Serenoa repens (LSESr) markedly inhibited both isozymes (Ki (type 1) = 8.4 nM and 7.2 μg/ml, respectively; Ki (type 2) = 7.4 nM and 4.9 μg/ml, respectively). The three azasteroids were competitive inhibitors vs substrate, whereas LSESr displayed non-competitive inhibition of the type 1 isozyme and uncompetitive inhibition of the type 2 isozyme. These observations suggest that the lipid component of LSESr might be responsible for its inhibitory effect by modulating the membrane environment of 5α-reductase. Partially purified recombinant 5α-reductase type 1 activity was preserved by the presence of lipids indicating that lipids can exert either stimulatory or inhibitory effects on human 5α-reductase. 相似文献
53.
54.
55.
Georges Olivier 《Journal of human evolution》1980,9(8):645-649
This study is divided in two parts. The first shows that the secular trend of increasing height is far from decreasing and, on the contrary, is accelerating. The second part attacks the problem of the causes of this phenomena. It shows that the increase of stature is linked to all indicators of the conditions of life, without any one factor being predominant. On the other hand, students of the more privileged back-grounds keep on showing this secular trend, though their life standards seems to be at the optimum. Therefore, the cause and the end of this phenomena cannot be demonstrated. 相似文献
56.
M T Priot-Droy L Olivier 《Comptes rendus des séances de la Société de biologie et de ses filiales》1979,173(1):14-19
Microfilamentous nuclear inculsions have been found at the ultrastructural level in the posterior epithelium of the rat pituitary cleft. They appear strictly located in ciliate cells of this epithelium. The microfilaments (7-8 nm in diameter) are gathered as a bundle. Their length is up to several microns and their average diameter is 0,35 micron. They can only be observed in adult rats. 相似文献
57.
Rosa Ventura Daniel Fraisse Michel Becchi Olivier Paisse Jordi Segura 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1991,562(1-2)
The application of thermospray and plasmaspray high-performance liquid chromatography—mass spectrometry to the analysis of diuretics and probenecid has been investigated. The latter method gave better ionization efficiency than the former, and its response was optimized by altering the solvent composition: best results were obtained with water—methanol—acetonitrile—trifluoroacetic acid. Using different proportions of these solvents, three isocratic systems were developed to separate the compounds under study. The principal characteristic of plasmaspray positive-ion mass spectra was a protonated molecular ion and very little fragmentation was evident. In the negative ionization mode, the plasmaspray method gave mass spectra showing more fragmentation, which resulted in additional structural information. The ability of trifluoroacetic acid to form negative cluster ions precluded its use as a mobile phase component. The minimum detectable amounts determined by the analysis in the positive-ion mode was compound-dependent, but generally ca. 10–150 ng. In many cases the compounds could be detected in urine extracts. 相似文献
58.
Jean- -François Laliberté Olivier Nicolas Serge Durand Rolf Morosoli 《Plant molecular biology》1992,18(3):447-451
The xylanase gene from Cryptococcus albidus contains seven introns. Genomic and cDNA clones under the control of the CaMV 35S promoter were transferred into tobacco plants using Agrobacterium-mediated cell transformation. The genes were transcribed and the mRNAs were amplified by the polymerase chain reaction using primers on each side of the intron region. About 90% of the amplification products from plants transformed with the genomic clone corresponded to the size of the pre-mRNA (1.2 kb) and 10% represented the spliced product (0.85 kb). The 0.85 kb fragment was cloned and sequenced and the result indicated that the introns from the xylanase gene were accurately spliced by the plant cells. 相似文献
59.
Three forms of phosphatase type 1 in Swiss 3T3 fibroblasts. Free catalytic subunit appears to mediate s6 dephosphorylation 总被引:4,自引:0,他引:4
The major 40 S ribosomal protein S6 phosphatase in Swiss mouse 3T3 fibroblasts is a type 1 enzyme (Olivier, A. R., Ballou, L. M., and Thomas, G. (1988) Proc. Natl. Acad. Sci. U. S. A. 85, 4720-4724). Polyclonal antibodies were raised against a synthetic peptide containing the carboxyl-terminal 14 amino acids of the catalytic subunit of phosphatase 1 (PP-1C). Results from Western blot analysis and immunoprecipitation show that the peptide antiserum specifically recognizes PP-1C in cell extracts. Anion-exchange chromatography of cell extracts and Western blot analysis revealed three peaks of PP-1C termed A, B, and C. Peaks A and C are associated with the major type 1 S6 phosphatase activities, but peak B exhibits little activity. The phosphatase in peak A (Mr 39,000) appears to represent the free catalytic subunit, whereas the enzymes in peaks B and C display sizes of 68,000-140,000. Peak B contains two additional proteins of Mr 26,000 and 48,000 that co-immunoprecipitate with PP-1C, while peak C has a single additional protein of Mr 100,000. Fifteen min after serum withdrawal there is a 2-fold stimulation of S6 phosphatase activity in peak A that can be accounted for by an increase in the amount of PP-1C. The amount of PP-1C in the inactive peak B fraction also increases during this time and this increase is associated with changes in the phosphorylation state of the Mr 26,000 and 48,000 proteins. The results are discussed in relation to regulatory mechanisms which are thought to modulate the activity of type 1 phosphatase. 相似文献
60.