全文获取类型
收费全文 | 10058篇 |
免费 | 731篇 |
国内免费 | 6篇 |
出版年
2022年 | 59篇 |
2021年 | 115篇 |
2020年 | 73篇 |
2019年 | 86篇 |
2018年 | 119篇 |
2017年 | 95篇 |
2016年 | 169篇 |
2015年 | 340篇 |
2014年 | 375篇 |
2013年 | 538篇 |
2012年 | 637篇 |
2011年 | 632篇 |
2010年 | 462篇 |
2009年 | 381篇 |
2008年 | 571篇 |
2007年 | 548篇 |
2006年 | 515篇 |
2005年 | 526篇 |
2004年 | 519篇 |
2003年 | 514篇 |
2002年 | 452篇 |
2001年 | 113篇 |
2000年 | 103篇 |
1999年 | 133篇 |
1998年 | 167篇 |
1997年 | 98篇 |
1996年 | 124篇 |
1995年 | 110篇 |
1994年 | 93篇 |
1993年 | 111篇 |
1992年 | 106篇 |
1991年 | 86篇 |
1990年 | 82篇 |
1989年 | 71篇 |
1988年 | 92篇 |
1987年 | 74篇 |
1986年 | 55篇 |
1985年 | 80篇 |
1984年 | 112篇 |
1983年 | 94篇 |
1982年 | 108篇 |
1981年 | 93篇 |
1980年 | 94篇 |
1979年 | 73篇 |
1978年 | 84篇 |
1977年 | 84篇 |
1976年 | 71篇 |
1975年 | 63篇 |
1974年 | 74篇 |
1973年 | 64篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
941.
942.
943.
Clapham KM Bardos J Finlay MR Golding BT Griffen EJ Griffin RJ Hardcastle IR Menear KA Ting A Turner P Young GL Cano C 《Bioorganic & medicinal chemistry letters》2011,21(3):966-970
Introduction of an O-alkoxyphenyl substituent at the 8-position of the 2-morpholino-4H-chromen-4-one pharmacophore enabled regions of the ATP-binding site of DNA-dependent protein kinase (DNA-PK) to be probed further. Structure-activity relationships have been elucidated for inhibition of DNA-PK and PI3K (p110α), with N-(2-(cyclopropylmethoxy)-4-(2-morpholino-4-oxo-4H-chromen-8-yl)phenyl)-2-morpholinoacetamide 11a being identified as a potent and selective DNA-PK inhibitor (IC50 = 8 nM). 相似文献
944.
945.
How common is speciation‐with‐gene‐flow? How much does gene flow impact on speciation? To answer questions like these requires understanding of the common obstacles to evolving reproductive isolation in the face of gene flow and the factors that favour this crucial step. We provide a common framework for the ways in which gene flow opposes speciation and the potential conditions that may ease divergence. This framework is centred on the challenge shared by most scenarios of speciation‐with‐gene‐flow, i.e. the need for coupling among different components of reproductive isolation. Using this structure, we review and compare the factors favouring speciation with the intention of providing a more integrated picture of speciation‐with‐gene‐flow. 相似文献
946.
Tobback J Boerjan B Vandersmissen HP Huybrechts R 《Insect biochemistry and molecular biology》2011,41(5):313-321
The circadian clocks govern many metabolic and behavioral processes in an organism. In insects, these clocks and their molecular machinery have been found to influence reproduction in many different ways. Reproductive behavior including courtship, copulation and egg deposition, is under strong influence of the daily rhythm. At the molecular level, the individual clock components also have their role in normal progress of oogenesis and spermatogenesis. In this study on the desert locust Schistocerca gregaria, three circadian clock genes were identified and their expression profiles were determined. High expression was predominantly found in reproductive tissues. Similar daily expression profiles were found for period (per) and timeless (tim), while the clock (clk) mRNA level is higher 12 h before the first per and tim peak. A knockdown of either per or tim resulted in a significant decrease in the progeny produced by dsRNA treated females confirming the role of clock genes in reproduction and providing evidence that both PER and TIM are needed in the ovaries for egg development. Since the knockdown of clk is lethal for the desert locust, its function remains yet to be elucidated. 相似文献
947.
Ranyuk ER Cauchon N Ali H Lecomte R Guérin B van Lier JE 《Bioorganic & medicinal chemistry letters》2011,21(24):7470-7473
Sulfonated metallo phthalocyanines (MPcS(n)) are second generation photosensitizers advanced for photodynamic therapy of various medical applications. A series of ZnPcS(n) was demetallated and subsequently converted to the corresponding [(64)Cu]CuPcS(n) in 40-50% isolated yields and >98% radiochemical purities. Tumor-bearing mice were injected with the (64)Cu-labeled products and subjected to 3-h dynamic PET imaging studies. Biodistribution patterns showed characteristic differences between the various derivatives. Tumor uptake was detected only for the amphiphilic derivatives [(64)Cu]CuPcS(2) and [(64)Cu]CuPcS(3)C(6) (1-1.5%ID/g). The biological data suggest that PET imaging with [(64)Cu]CuPc can be used to establish structure-PDT efficacy relationships for Pc-based photosensitizers. 相似文献
948.
Miles TJ Barfoot C Brooks G Brown P Chen D Dabbs S Davies DT Downie DL Eyrisch S Giordano I Gwynn MN Hennessy A Hoover J Huang J Jones G Markwell R Rittenhouse S Xiang H Pearson N 《Bioorganic & medicinal chemistry letters》2011,21(24):7483-7488
As part of our wider efforts to exploit novel mode of action antibacterials, we have discovered a series of cyclohexyl-amide compounds that has good Gram positive and Gram negative potency. The mechanism of action is via inhibition of bacterial topoisomerases II and IV. We have investigated various subunits in this series and report advanced studies on compound 7 which demonstrates good PK and in vivo efficacy properties. 相似文献
949.
Miles TJ Axten JM Barfoot C Brooks G Brown P Chen D Dabbs S Davies DT Downie DL Eyrisch S Gallagher T Giordano I Gwynn MN Hennessy A Hoover J Huang J Jones G Markwell R Miller WH Minthorn EA Rittenhouse S Seefeld M Pearson N 《Bioorganic & medicinal chemistry letters》2011,21(24):7489-7495
We have identified a series of amino-piperidine antibacterials with a good broad spectrum potency. We report the investigation of various subunits in this series and advanced studies on compound 8. Compound 8 possesses good pharmacokinetics, broad spectrum antibacterial activity and demonstrates oral efficacy in a rat lung infection model. 相似文献
950.
Spliceosomal introns are hallmarks of most eukaryotic genomes and are excised from premature mRNAs by a spliceosome that is among the largest, and most complex, molecular machine in cells. The divergent unicellular eukaryote Giardia intestinalis, the causative agent of giardiasis, also possesses spliceosomes, but only four canonical (cis-spliced) introns have been identified in its genome to date. We demonstrate that this organism has a novel form of spliceosome-mediated trans-splicing of split introns that is essential for generating mature mRNAs for at least two important genes: one encoding a heat shock protein 90 (HSP90), which controls the conformation of a suite of cellular proteins, and the other encoding a dynein molecular motor protein, involved in the motility of eukaryotic flagella. These split introns have properties that distinguish them from other trans-splicing systems known within eukaryotes, suggesting that Giardia independently evolved a unique system to splice split introns. 相似文献