全文获取类型
收费全文 | 28927篇 |
免费 | 2202篇 |
国内免费 | 1678篇 |
专业分类
32807篇 |
出版年
2024年 | 75篇 |
2023年 | 369篇 |
2022年 | 838篇 |
2021年 | 1332篇 |
2020年 | 910篇 |
2019年 | 1162篇 |
2018年 | 1157篇 |
2017年 | 899篇 |
2016年 | 1226篇 |
2015年 | 1740篇 |
2014年 | 2007篇 |
2013年 | 2285篇 |
2012年 | 2554篇 |
2011年 | 2300篇 |
2010年 | 1318篇 |
2009年 | 1190篇 |
2008年 | 1372篇 |
2007年 | 1248篇 |
2006年 | 1138篇 |
2005年 | 982篇 |
2004年 | 893篇 |
2003年 | 731篇 |
2002年 | 721篇 |
2001年 | 493篇 |
2000年 | 480篇 |
1999年 | 414篇 |
1998年 | 296篇 |
1997年 | 254篇 |
1996年 | 260篇 |
1995年 | 235篇 |
1994年 | 198篇 |
1993年 | 151篇 |
1992年 | 201篇 |
1991年 | 189篇 |
1990年 | 150篇 |
1989年 | 116篇 |
1988年 | 124篇 |
1987年 | 121篇 |
1986年 | 80篇 |
1985年 | 102篇 |
1984年 | 79篇 |
1983年 | 60篇 |
1982年 | 33篇 |
1981年 | 29篇 |
1980年 | 24篇 |
1979年 | 35篇 |
1978年 | 28篇 |
1977年 | 20篇 |
1975年 | 29篇 |
1974年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Zemliakova VV Strel'nikov VV Zborovskaia IB Balukova OV Maĭorova OA Vasil'ev EV Zaletaev DV Nemtsova MV 《Molekuliarnaia biologiia》2004,38(6):966-972
Multiplex methylation-sensitive PCR and methylation-specific PCR were employed in studying the methylation of CpG islands in the p16/CDKN2A and p14/ARF promoter and the first exon regions in non-small cell lung cancer (54 samples) and acute B-cell lymphoblastic leukemia (61 samples). Differences in methylation were detected between types of neoplasia as well as between CpG islands studied within the same types of tumors. High level of the p16/CDKN2A first exon CpC island methylation was revealed in non-small cell lung cancer (68%) and in acute B-cell lymphoblastic leukemia (55%) and the CpG island of p14/ARF first exon was nonmethylated in these types of tumors. The methylation of CpG-rich fragments of genes p16/CDKN2A and p14/ARF promoters was analysed. As was found out, CpG islands located in 5' areas of one and the same gene can differ in methylation frequencies. The comparison of sensitivity between methylation-specific PCR and methylation-sensitive PCR used in the methylations studies was carried out. 相似文献
42.
Functional & Integrative Genomics - DNAJ proteins function as co-chaperones of HSP70 and play key roles in cell physiology to promote protein folding and degradation, especially under... 相似文献
43.
Three-dimensional quantitative structure–activity relationship (3D-QSAR) studies were performed on a series of substituted 1,4-dihydroindeno[1,2-c]pyrazoles inhibitors, using molecular docking and comparative molecular field analysis (CoMFA). The docking results from GOLD 3.0.1 provide a reliable conformational alignment scheme for the 3D-QSAR model. Based on the docking conformations and alignments, highly predictive CoMFA model was built with cross-validated q 2 value of 0.534 and non-cross-validated partial least-squares analysis with the optimum components of six showed a conventional r 2 value of 0.911. The predictive ability of this model was validated by the testing set with a conventional r 2 value of 0.812. Based on the docking and CoMFA, we have identified some key features of the 1,4-dihydroindeno[1,2-c]pyrazoles derivatives that are responsible for checkpoint kinase 1 inhibitory activity. The analyses may be used to design more potent 1,4-dihydroindeno[1,2-c]pyrazoles derivatives and predict their activity prior to synthesis. 相似文献
44.
A thermophilic bacterial strain GXN151 which could degrade Avicel efficiently was isolated and identified as Bacillus licheniformis. A genomic library of GXN151 was constructed and two novel endoglucanase genes designated cel9A and cel12A were isolated by screening the library on carboxylmethyl cellulase indicator plates. The analysis of amino acid sequences deduced from the genes indicated that Cel9A consisted of a catalytic domain belonging to glycosyl hydrolase family 9, a linker domain, and a carbohydrate binding module family 3 from N-terminal to C-terminal; Cel12A had only one catalytic domain belonging to glycosyl hydrolase family 12. The combinations of Cel9A and Cel12A produced by the recombinant E. coli exhibited synergistic action against substrates of carboxylmethyl cellulose as well as Avicel. 相似文献
45.
The recent genome-wide association study identified a link between vitiligo and genetic variants in the ribonuclease T2 (RNASET2) gene; however, the functional roles of RNASET2 in vitiligo pathogenesis or in melanocyte apoptosis have yet to be determined. The current study was designed to investigate the vitiligo-related expression pattern of RNASET2 and its molecular function involving apoptosis-related signaling proteins and pathways. The results showed overexpression of RNASET2 in epidermis specimens from 40 vitiligo patients compared with that from matched healthy controls. In addition, in vitro analyses indicated that overexpression of RNASET2 was inducible in cultured primary human melanocytes and keratinocytes by stress conditions, that is, exposure to UV irradiation, hydrogen peroxide, and inflammatory factors, respectively, and led to increased cell apoptosis via the tumor necrosis factor receptor-associated factor 2 (TRAF2)–caspases pathway through the physical interaction of RNASET2 with TRAF2. Thus, RNASET2 may contribute to vitiligo pathogenesis by inhibiting TRAF2 expression and, as such, RNASET2 may represent a potential therapeutic target of vitiligo. 相似文献
46.
48.
Xin Zhong Yang Yang Jing Zhao Binbin Gong Jingrui Li Xiaolei Wu Hongbo Gao Guiyun Lü 《The Plant Pathology Journal》2022,38(3):229
Fusarium wilt caused by Fusarium oxysporum f. sp. niveum (Fon) is the most serious soil-borne disease in the world and has become the main limiting factor of watermelon production. Reliable and quick detection and quantification of Fon are essential in the early stages of infection for control of watermelon Fusarium wilt. Traditional detection and identification tests are laborious and cannot efficiently quantify Fon isolates. In this work, a real-time polymerase chain reaction (PCR) assay has been described to accurately identify and quantify Fon in watermelon plants and soil. The FONRT-18 specific primer set which was designed based on identified specific sequence amplified a specific 172 bp band from Fon and no amplification from the other formae speciales of Fusarium oxysporum tested. The detection limits with primers were 1.26 pg/μl genomic DNA of Fon, 0.2 pg/ng total plant DNA in inoculated plant, and 50 conidia/g soil. The PCR assay could also evaluate the relationships between the disease index and Fon DNA quantity in watermelon plants and soil. The assay was further used to estimate the Fon content in soil after disinfection with CaCN2. The real-time PCR method is rapid, accurate and reliable for monitoring and quantification analysis of Fon in watermelon plants and soil. It can be applied to the study of disease diagnosis, plant-pathogen interactions, and effective management. 相似文献
49.