全文获取类型
收费全文 | 8494篇 |
免费 | 931篇 |
出版年
2022年 | 62篇 |
2021年 | 195篇 |
2020年 | 99篇 |
2019年 | 124篇 |
2018年 | 143篇 |
2017年 | 125篇 |
2016年 | 241篇 |
2015年 | 401篇 |
2014年 | 405篇 |
2013年 | 471篇 |
2012年 | 568篇 |
2011年 | 613篇 |
2010年 | 381篇 |
2009年 | 345篇 |
2008年 | 472篇 |
2007年 | 443篇 |
2006年 | 439篇 |
2005年 | 418篇 |
2004年 | 370篇 |
2003年 | 327篇 |
2002年 | 279篇 |
2001年 | 173篇 |
2000年 | 158篇 |
1999年 | 135篇 |
1998年 | 90篇 |
1997年 | 73篇 |
1996年 | 63篇 |
1995年 | 65篇 |
1994年 | 64篇 |
1993年 | 72篇 |
1992年 | 124篇 |
1991年 | 102篇 |
1990年 | 112篇 |
1989年 | 92篇 |
1988年 | 91篇 |
1987年 | 79篇 |
1986年 | 62篇 |
1985年 | 72篇 |
1984年 | 62篇 |
1983年 | 61篇 |
1982年 | 44篇 |
1981年 | 34篇 |
1980年 | 33篇 |
1979年 | 54篇 |
1978年 | 48篇 |
1977年 | 47篇 |
1976年 | 46篇 |
1974年 | 36篇 |
1973年 | 38篇 |
1969年 | 40篇 |
排序方式: 共有9425条查询结果,搜索用时 31 毫秒
131.
Identification of a cDNA encoding a long form of prolactin receptor in human hepatoma and breast cancer cells 总被引:19,自引:0,他引:19
J M Boutin M Edery M Shirota C Jolicoeur L Lesueur S Ali D Gould J Djiane P A Kelly 《Molecular endocrinology (Baltimore, Md.)》1989,3(9):1455-1461
Human PRL receptor cDNA clones from hepatoma (Hep G2) and breast cancer (T-47D) libraries were isolated by using a rat PRL receptor cDNA probe. The nucleotide sequence predicts a mature protein of 598 amino acids with a much longer cytoplasmic domain than the rat liver PRL receptor. Although this extended region has additional segments of localized sequence identity with the human GH receptor, there is no identity with any consensus sequences known to be involved in hormonal signal transduction. This cDNA will be a valuable tool to better understand the role of PRL in the development and growth of human breast cancer. 相似文献
132.
Measurement of PGE2 as the methyl oxime by radioimmunoassay using a novel iodinated label 总被引:3,自引:0,他引:3
R W Kelly B J Graham M J O'Sullivan 《Prostaglandins, leukotrienes, and essential fatty acids》1989,37(3):187-191
A radioimmunoassay has been developed for prostaglandin E2 (PGE2) using methyl oxime (MOX) derivatisation and a novel 125Iodine radiolabel. PGE2-methyl oxime (PGE2-MOX) is coupled through an imide linkage to proline in a pro-gly-tyr or similar peptide rather than through the conventional amide linkage to histamine or tyrosine methyl ester. The main advantage of this method is that the imide linkage in the label does not resemble the amide link used in the original antigen and the conjugate is therefore readily displaced by the natural PGE2. This overcomes the traditional difficulty encountered in hapten RIAs where the antiserum has a higher affinity for the label than it has for the compound to be measured. The assay that has been developed using these modifications and a solid-phase second antibody separation step, is both sensitive (with a lower detection limit of 0.5 pg/tube), reliable and simple and has the advantage that methyl oximation of the sample protects the PGE from degrading prior to and during the assay. 相似文献
133.
134.
Eubacterial isocitrate dehydrogenase with dual specificity for NAD and NADP from Rhodomicrobium vannielii 总被引:1,自引:0,他引:1
Abstract Cell-free extracts of the photosynthetic eubacterium Rhodomicrobium vannielii contained both NADP and NAD-linked isocitrate dehydrogenase activities. Apparent K m values of 12 μM for NADP, 0.75 mM for NAD, 9.3 μM for isocitrate (NADP utilising) and 8.2 μM for isocitrate (NAD utilising) were determined in such extracts. Four lines of evidence indicated that one enzyme was responsible for the two activities; (i) non-additivity of reaction rates in the presence of both NADP and NAD (ii) the presence of one band which stained for activity with both cofactors on non-denaturing polyacrylamide gels (iii) identical heat inactivation kinetics for both activities (iv) co-elution of both activities after ion-exchange and hydrophobic interaction chromatography. This is the first report of a eubacterial isocitrate dehydrogenase with dual cofactor specificity. 相似文献
135.
T P Haverty M Watanabe E G Neilson C J Kelly 《Journal of immunology (Baltimore, Md. : 1950)》1989,143(4):1133-1141
136.
Human papillomavirus type 48. 总被引:3,自引:1,他引:2
The cloning and partial characterization of the genome of human papillomavirus (HPV) type 48 is presented. Hybridization and short DNA sequence analyses permitted the alignment of the genome to the HPV genetic map. 相似文献
137.
Molecular genetic study of the frequency of monosomy 22q11 in DiGeorge syndrome 总被引:10,自引:2,他引:8 下载免费PDF全文
A. H. Carey D. Kelly S. Halford R. Wadey D. Wilson J. Goodship J. Burn T. Paul A. Sharkey J. Dumanski M. Nordenskjold R. Williamson P. J. Scambler 《American journal of human genetics》1992,51(5):964-970
It is well established that DiGeorge syndrome (DGS) may be associated with monosomy of 22q11-pter. More recently, DNA probes have been used to detect hemizygosity for this region in patients with no visible karyotypic abnormality. However, DGS has also been described in cases where the cytogenetic abnormality does not involve 22q11; for instance, four cases of 10p- have been reported. In this study we have prospectively analyzed patients, by using DNA markers from 22q11, to assess the frequency of 22q11 rearrangements in DGS. Twenty-one of 22 cases had demonstrable hemizygosity for 22q11. Cytogenetic analysis had identified interstitial deletion in 6 of 16 cases tested; in 6 other cases no karyotype was available. When these results are combined with those from our previous studies, 33 of 35 DGS patients had chromosome 22q11 deletions detectable by DNA probes. 相似文献
138.
Minimum qualifications for directors: DNA-based genetic-testing laboratories. DNA Testing Subcommittee, Quality Assurance Committee, Council of Regional Networks for Genetic Services. 下载免费PDF全文
139.
140.