全文获取类型
收费全文 | 1980篇 |
免费 | 92篇 |
专业分类
2072篇 |
出版年
2023年 | 27篇 |
2022年 | 23篇 |
2021年 | 46篇 |
2020年 | 24篇 |
2019年 | 36篇 |
2018年 | 59篇 |
2017年 | 44篇 |
2016年 | 51篇 |
2015年 | 92篇 |
2014年 | 120篇 |
2013年 | 142篇 |
2012年 | 172篇 |
2011年 | 151篇 |
2010年 | 88篇 |
2009年 | 85篇 |
2008年 | 120篇 |
2007年 | 91篇 |
2006年 | 91篇 |
2005年 | 79篇 |
2004年 | 65篇 |
2003年 | 61篇 |
2002年 | 55篇 |
2001年 | 29篇 |
2000年 | 33篇 |
1999年 | 24篇 |
1998年 | 11篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 12篇 |
1994年 | 5篇 |
1993年 | 11篇 |
1992年 | 12篇 |
1991年 | 17篇 |
1990年 | 18篇 |
1989年 | 24篇 |
1988年 | 11篇 |
1987年 | 14篇 |
1986年 | 22篇 |
1985年 | 11篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 12篇 |
1980年 | 5篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1972年 | 3篇 |
1969年 | 4篇 |
排序方式: 共有2072条查询结果,搜索用时 15 毫秒
41.
Ram S. Verma Arvind Babu Sundari Chemitiganti Harvey Dosik 《Molecular & general genetics : MGG》1986,202(3):339-341
Summary A possible cause of non-disjunction of chromosome 21 in Down Syndromes has been cytogenetically evaluated by examining the parents by Ag-staining technique. In all the cases studied so far, the contributing parents have active ribosomal cistrons on both chromosomes 21 i.e. both chromosomes are stained positively by silver staining. These results show that the active NORs might play an essential role in meiotic non-disjunction. Furthermore, the preliminary results demonstrate that the acrocentric associations of homologous and non-homologous nature involving chromosome 21 are the most frequent in the contributing parent which may further indicate the role of multiple cellular factors affecting the associations in promoting the non-disjunction in addition to active NORs. The possible mechanisms regarding the non-disjunction of chromosome 21 have been described.Presented at the 34th Annual Meeting of the American Society of Human Genetics, Norfolk, VA, USA 相似文献
42.
Unnikrishnan Parayil Babu Velukutty Anu Gopinath 《Chemical Speciation and Bioavailability》2013,25(4):153-167
AbstractConcentrations of heavy metals (Cd, Co, Cr, Cu and Fe) in surface sediments and their partitioning behaviour between exchangeable, reducible (Fe-Mn oxide bound) and organic/residual phases of the sediments in a typical backwater system of Kerala, viz. the southern upstream part of Cochin Estuarine System (South India), have been studied. Spatial and temporal variations of trace metals are discussed with special reference to pH, dissolved oxygen, salinity, organic carbon and texture of sediment. Metal concentrations in the tide gated part of the estuary were found to be significantly higher when compared to metal concentrations reported from the unrestricted part of the Cochin estuarine system and also those from many of the unpolluted estuaries worldwide. The higher levels of heavy metals in the study area and their characteristic distribution and partitioning behaviour in the surficial sediments were attributed to the presence of a salinity barrier across the backwater system and also by the massive use of pesticides and chemical fertilizers in the vast area of agricultural land near the backwater system. 相似文献
43.
44.
Pandey Abhay K. Deka Bhabesh Varshney Richa Cheramgoi Evelyn Chepkirui Babu Azariah 《BioControl》2021,66(4):445-462
BioControl - In recent years, Fungal Biocontrol Agents (FBCAs) have played a significant role in the biological control of pests and plant pathogens of several economically important crops,... 相似文献
45.
Matthew Bovyn Babu Reddy Janakaloti Narayanareddy Steven Gross Jun Allard 《Molecular biology of the cell》2021,32(9):984
Cellular cargoes, including lipid droplets and mitochondria, are transported along microtubules using molecular motors such as kinesins. Many experimental and computational studies focused on cargoes with rigidly attached motors, in contrast to many biological cargoes that have lipid surfaces that may allow surface mobility of motors. We extend a mechanochemical three-dimensional computational model by adding coupled-viscosity effects to compare different motor arrangements and mobilities. We show that organizational changes can optimize for different objectives: Cargoes with clustered motors are transported efficiently but are slow to bind to microtubules, whereas those with motors dispersed rigidly on their surface bind microtubules quickly but are transported inefficiently. Finally, cargoes with freely diffusing motors have both fast binding and efficient transport, although less efficient than clustered motors. These results suggest that experimentally observed changes in motor organization may be a control point for transport. 相似文献
46.
Prashanthi M. Babu H. Ramesh Rani Janapatla Uma 《Russian Journal of Bioorganic Chemistry》2021,47(2):601-608
Russian Journal of Bioorganic Chemistry - In search of better antibacterial agents, a series of novel 5-((aryl)methyl)-3-(1H-indol-2-yl)isoxazole (IIIa–e) and... 相似文献
47.
Ruth Muchekehu Dingguo Liu Mark Horn Lioudmila Campbell Joselyn Del Rosario Michael Bacica Haim Moskowitz Trina Osothprarop Anouk Dirksen Venkata Doppalapudi Allan Kaspar Steven R. Pirie-Shepherd Julia Coronella 《Translational oncology》2013,6(5):562-IN6
Poor drug delivery and penetration of antibody-mediated therapies pose significant obstacles to effective treatment of solid tumors. This study explored the role of pharmacokinetics, valency, and molecular weight in maximizing drug delivery. Biodistribution of a fibroblast growth factor receptor 4 (FGFR4) targeting CovX-body (an FGFR4-binding peptide covalently linked to a nontargeting IgG scaffold; 150 kDa) and enzymatically generated FGFR4 targeting F(ab)2 (100 kDa) and Fab (50 kDa) fragments was measured. Peak tumor levels were achieved in 1 to 2 hours for Fab and F(ab)2versus 8 hours for IgG, and the percentage injected dose in tumors was 0.45%, 0.5%, and 2.5%, respectively, compared to 0.3%, 2%, and 6% of their nontargeting controls. To explore the contribution of multivalent binding, homodimeric peptides were conjugated to the different sized scaffolds, creating FGFR4 targeting IgG and F(ab)2 with four peptides and Fab with two peptides. Increased valency resulted in an increase in cell surface binding of the bivalent constructs. There was an inverse relationship between valency and intratumoral drug concentration, consistent with targeted consumption. Immunohistochemical analysis demonstrated increased size and increased cell binding decreased tumor penetration. The binding site barrier hypothesis suggests that limited tumor penetration, as a result of high-affinity binding, could result in decreased efficacy. In our studies, increased target binding translated into superior efficacy of the IgG instead, because of superior inhibition of FGFR4 proliferation pathways and dosing through the binding site barrier. Increasing valency is therefore an effective way to increase the efficacy of antibody-based drugs. 相似文献
48.
Shiwani Rana Anand Babu Velappan 《Journal of biomolecular structure & dynamics》2020,38(16):4914-4920
Communicated by Ramaswamy H. Sarma 相似文献
49.
Kumar Alok Singh Pradyumn Pandey Anshuman Gosipatala Sunil Babu 《Molecular biology reports》2020,47(9):6919-6927
Molecular Biology Reports - Promoter methylation mediated silencing of tumor suppressor genes plays an important role in the tumorigenesis of colorectal carcinoma (CRC). Tumor suppressor gene,... 相似文献
50.
Monika Chaudhary Neeraj Kumar Ashish Baldi Ramesh Chandra M. Arockia Babu 《Journal of biomolecular structure & dynamics》2020,38(1):200-218
AbstractWith an endeavor to develop novel curcumin analogs as potential anti-cancer agents, we designed and synthesized a series of Knoevenagel condensates by clubbing pyrazole carbaldehydes at the active methylene carbon atom of the curcumin backbone. Molecular docking studies were carried out to target the proposed derivatives on human kinase β (IKKβ), a potential anti-cancer target. The chloro derivative displayed five hydrogen bond interactions with a docking score of ?11.874?kcal/mol higher than curcumin (docking score =??7.434?kcal/mol). This was supported by the fact that the propellant shaped derivatives fitted aptly into the binding pocket. Molecular simulations studies were also conducted on the lead molecule and the results figured out that the stable complexes were developed as the minimal deviations per residue of protein within the range of 0.11–0.92 Å. The screened compounds were synthesized, characterized and evaluated in vitro for cytotoxicity against cervical cancer cell line, HeLa using standard cell proliferation assay. Chloro derivative and bromo analog demonstrated IC50 (half maximal inhibitory concentration) value of 14.2 and 18.6 µg/ml, respectively, significantly lower than 42.4 µg/ml of curcumin and higher than 0.008 µg/ml of paclitaxel. Induction of apoptosis was evaluated in the terms of cleavage of caspase-3 enzyme and they also exhibited 69.6 and 65.4% of apoptosis significantly higher than 19.9% induced by curcumin. In conclusion, chloro and bromo derivatives must be evaluated under a set of stringent in vitro and in vivo parameters for translating in to a clinically viable product.Communicated by Ramaswamy H. Sarma 相似文献