全文获取类型
收费全文 | 844篇 |
免费 | 45篇 |
出版年
2023年 | 4篇 |
2022年 | 6篇 |
2021年 | 20篇 |
2020年 | 9篇 |
2019年 | 14篇 |
2018年 | 20篇 |
2017年 | 11篇 |
2016年 | 19篇 |
2015年 | 19篇 |
2014年 | 47篇 |
2013年 | 83篇 |
2012年 | 48篇 |
2011年 | 46篇 |
2010年 | 33篇 |
2009年 | 29篇 |
2008年 | 53篇 |
2007年 | 41篇 |
2006年 | 32篇 |
2005年 | 46篇 |
2004年 | 35篇 |
2003年 | 28篇 |
2002年 | 36篇 |
2001年 | 19篇 |
2000年 | 23篇 |
1999年 | 16篇 |
1998年 | 11篇 |
1997年 | 14篇 |
1996年 | 9篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 9篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 15篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1976年 | 9篇 |
1975年 | 3篇 |
1973年 | 4篇 |
1970年 | 2篇 |
1962年 | 2篇 |
排序方式: 共有889条查询结果,搜索用时 15 毫秒
91.
Topical application of DEET for schistosomiasis 总被引:1,自引:0,他引:1
N, N-diethyl-m-toluamide (also known as DEET) is a broad-spectrum insect repellent that is used extensively against both human and animal pests, worldwide. Recent studies show that topical lipid formulations of DEET, such as LipoDEET, are highly effective in killing schistosome cercariae in the skin. Minimal systemic absorption, low manufacturing cost, and a wide range of activity against insects and schistosomes potentially makes compounds such as LipoDEET an excellent prophylactic agent against human and animal schistosomiasis in endemic areas, especially for travelers, until an effective vaccine is available. 相似文献
92.
93.
Subramanium Vimaladevi Ayyavu Mahesh Balaji N. Dhayanithi Nattarayan Karthikeyan 《Biologia》2012,67(1):212-216
Mosquito larvicidal and repellent activities of phenolic acids of Chaetomorpha antennina (Bory) Kuetz. against the third instar larvae of Aedes aegypti were investigated. The larval mortality was observed after 24 h exposure. Results of mosquito larvicidal tests revealed that
insoluble bound phenolic acids and soluble conjugated phenolic acid fractions of C. antennina had an excellent inhibitory
effect against A. aegypti and its LC50 values were 23.4 and 44.6 μg ml−1, respectively. The repellency assay of insoluble bound phenolic acids and soluble conjugated phenolic acid fractions of C. antennina, at 10 μg cm−2 concentration gave 100% protection up to 120 min. The results indicate that phenolic acids of C. antennina have a wide spectrum of larvicidal and repellent activities against Aedes aegypti. 相似文献
94.
95.
A. Karthikeyan J. Shilpha S. Karutha Pandian M. Ramesh 《Plant Cell, Tissue and Organ Culture》2012,109(1):153-165
A reproducible and highly efficient protocol for Agrobacterium tumefaciens-mediated transformation of indica rice (Oryza sativa L. subsp. indica cv. ADT 43) was established. Prior to transformation, embryogenic callus were induced from mature seeds incubated on Linsmaier
and Skoog (LS) medium supplemented with 2.5 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.0 mg l−1 thiamine-HCl. Callus, intact mature seeds, and other in vitro derived explants (leaf bases, leaf blades, coleoptiles, and
root-tips) were immersed in a bacterial suspension culture of A. tumefaciens strain EHA 105, OD600 of 0.8, and co-cultivated on LS medium for 2 days in the dark at 25 ± 2°C. Based on GUS expression
analysis, 10 min incubation time of explants on a co-cultivation medium containing 100 μM acetosyringone was optimum. Following
β-glucuronidase (GUS) assay and polymerase chain reaction (PCR) analysis, transformants were identified. Stable integration
of the transgene was confirmed in four putatively transformed T0 plants by Southern blot analysis. The copy number of the transgene in these lines, one to two, was then determined. Among
the observations made, necrosis of co-cultivated explants was a problem, as well as sensitivity of callus to Agrobacterium infection. Levels of necrosis could be minimized following co-cultivation of explants in a medium consisting of 30% LS and
containing 10 g l−1 (14), polyvinyl pyrrolidone, 10% coconut water, and 250 mg l−1 timentin (15:1). This latter medium also increased the final transformation efficiency to 15.33%. 相似文献
96.
Hongyu Tian Karthikeyan Mythreye Christelle Golzio Nicholas Katsanis Gerard C Blobe 《The EMBO journal》2012,31(19):3885-3900
Both the transforming growth factor β (TGF-β) and integrin signalling pathways have well-established roles in angiogenesis. However, how these pathways integrate to regulate angiogenesis is unknown. Here, we show that the extracellular matrix component, fibronectin, and its cellular receptor, α5β1 integrin, specifically increase TGF-β1- and BMP-9-induced Smad1/5/8 phosphorylation via the TGF-β superfamily receptors endoglin and activin-like kinase-1 (ALK1). Fibronectin and α5β1 integrin increase Smad1/5/8 signalling by promoting endoglin/ALK1 cell surface complex formation. In a reciprocal manner, TGF-β1 activates α5β1 integrin and downstream signalling to focal adhesion kinase (FAK) in an endoglin-dependent manner. α5β1 integrin and endoglin form a complex on the cell surface and co-internalize, with their internalization regulating α5β1 integrin activation and signalling. Functionally, endoglin-mediated fibronectin/α5β1 integrin and TGF-β pathway crosstalk alter the responses of endothelial cells to TGF-β1, switching TGF-β1 from a promoter to a suppressor of migration, inhibiting TGF-β1-mediated apoptosis to promote capillary stability, and partially mediating developmental angiogenesis in vivo. These studies provide a novel mechanism for the regulation of TGF-β superfamily signalling and endothelial function through crosstalk with integrin signalling pathways. 相似文献
97.
Ramaswamy Govindan Li Ding Malachi Griffith Janakiraman Subramanian Nathan D. DeesKrishna L. Kanchi Christopher A. Maher Robert Fulton Lucinda Fulton John Wallis Ken ChenJason Walker Sandra McDonald Ron Bose David OrnitzDonghai Xiong Ming YouDavid J. Dooling Mark Watson Elaine R. Mardis Richard K. Wilson 《Cell》2012,150(6):1121-1134
98.
Venkat Ragavan R Vijayakumar V Rajesh K Palakshi Reddy B Karthikeyan S Suchetha Kumari N 《Bioorganic & medicinal chemistry letters》2012,22(12):4193-4197
A series of β-keto esters were synthesized from heteroaryl esters and ethyl acetate using LiHMDS as base at -50 to -30 °C. The increase in yields of cross condensed product were observed and the percentage of self condensed product was reduced drastically by applying the suitable base (LiHMDS), solvent and the minimum amount of ethyl acetate. All these β-keto esters were characterized using (1)H NMR, (13)C NMR and mass spectral data. A plausible mechanism is also depicted to prove the formation of trans-esterified products. All the synthesized compounds were subjected to test for their cytotoxicity towards various cancer cell lines and also tested for their antimicrobial activity towards various bacterial and fungal strains and some of them were found to have promising activity. 相似文献
99.
Ashraf Ali M Ismail R Choon TS Kumar RS Osman H Arumugam N Almansour AI Elumalai K Singh A 《Bioorganic & medicinal chemistry letters》2012,22(1):508-511
Pyrrolothiazolyloxindole analogues share vital pharmacological properties, considered useful in Alzheimer's disease (AD). The aim of this study was synthesis and evaluate pyralothiazolyloxindole analogues if possess acetyl cholinesterase (AChE) inhibitory activity. The easily accessible one-pot synthesis of these compounds resulted to be significantly less difficult and expensive than that of donepezil. Several compounds possess anti-cholinesterase activity in the order of micro and sub-micromolar. Particularly, compound was the most potent inhibitors of the series against acetyl cholinesterase enzyme with IC(50) 0.11μmol/L. 相似文献
100.
Dakshinamoorthy G Samykutty AK Munirathinam G Shinde GB Nutman T Reddy MV Kalyanasundaram R 《PloS one》2012,7(4):e34077
Filarial nematodes enjoy one of the longest life spans of any human pathogen due to effective immune evasion strategies developed by the parasite. Among the various immune evasion strategies exhibited by the parasite, Interleukin 10 (IL-10) productions and IL-10 mediated immune suppression has significant negative impact on the host immune system. Recently, we identified a small heat shock protein expressed by Brugia malayi (BmHsp12.6) that can bind to soluble human IL-10 receptor alpha (IL-10R) and activate IL-10 mediated effects in cell lines. In this study we show that the IL-10R binding region of BmHsp12.6 is localized to its N-terminal region. This region has significant sequence similarity to the receptor binding region of human IL-10. In vitro studies confirm that the N-terminal region of BmHsp12.6 (N-BmHsp12.6) has IL-10 like activity and the region containing the alpha crystalline domain and C-terminus of BmHsp12.6 (BmHsp12.6αc) has no IL-10 like activity. However, BmHsp12.6αc contains B cell, T cell and CTL epitopes. Members of the sHSP families are excellent vaccine candidates. Evaluation of sera samples from putatively immune endemic normal (EN) subjects showed IgG1 and IgG3 antibodies against BmHsp12.6αc and these antibodies were involved in the ADCC mediated protection. Subsequent vaccination trials with BmHsp12.6αc in a mouse model using a heterologous prime boost approach showed that 83% protection can be achieved against B. malayi L3 challenge. Results presented in this study thus show that the N-BmHsp12.6 subunit of BmHsp12.6 has immunoregulatory function, whereas, the BmHsp12.6αc subunit of BmHsp12.6 has significant vaccine potential. 相似文献