全文获取类型
收费全文 | 655篇 |
免费 | 34篇 |
国内免费 | 1篇 |
专业分类
690篇 |
出版年
2022年 | 10篇 |
2021年 | 28篇 |
2020年 | 18篇 |
2019年 | 3篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 7篇 |
2015年 | 14篇 |
2014年 | 18篇 |
2013年 | 36篇 |
2012年 | 42篇 |
2011年 | 38篇 |
2010年 | 26篇 |
2009年 | 25篇 |
2008年 | 37篇 |
2007年 | 33篇 |
2006年 | 27篇 |
2005年 | 25篇 |
2004年 | 22篇 |
2003年 | 20篇 |
2002年 | 10篇 |
2001年 | 17篇 |
2000年 | 17篇 |
1999年 | 19篇 |
1998年 | 7篇 |
1997年 | 17篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 3篇 |
1992年 | 10篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 10篇 |
1986年 | 10篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 9篇 |
1976年 | 3篇 |
1972年 | 6篇 |
1966年 | 2篇 |
1965年 | 3篇 |
1963年 | 3篇 |
排序方式: 共有690条查询结果,搜索用时 0 毫秒
631.
Jayaraman Selvaraj Umapathy Vidhya Rekha Shazia Fathima JH Venkatacalam Sivabalan Rajagopal Ponnulakshmi Veeraraghavan Vishnupriya Malathi Kullappan Radhika nalinakumari Sreekandan Surapaneni Krishna Mohan 《Bioinformation》2021,17(1):167
It is of interest to document the moelcular docking analysis of SARS-CoV-2 linked RNA dependent RNA polymerase (RdRp) with compounds from Plectranthus amboinicus. Hence, we report the binding features of rutin, Luteolin, Salvianolic acid A, Rosmarinic acid and p-Coumaric acid with the target protein SARS-CoV-2 linked RNA dependent RNA polymerase (RdRp) for further consideration. 相似文献
632.
Selvaraj Jayaraman Vidhya Rekha Umapathy Jayamathi Govindaraj Keerthidaa Govidaraj 《Bioinformation》2021,17(1):223
It is known that vascular endothelial growth factor receptor (VGFR) is linked with cancer. Therefore, it is of interest to document the molecular binding features of bioactive molecules from Piper longum as potential anti-cancer agents with VGFR2 for further consideration. Thus, we document the binding features of four compounds (sesamin, fargesin, longamide and piperlonguminine) with VGFR2 for further consideration in drug discovery. 相似文献
633.
Idicula-Thomas S Kulkarni AJ Kulkarni BD Jayaraman VK Balaji PV 《Bioinformatics (Oxford, England)》2006,22(3):278-284
MOTIVATION: Inclusion body formation has been a major deterrent for overexpression studies since a large number of proteins form insoluble inclusion bodies when overexpressed in Escherichia coli. The formation of inclusion bodies is known to be an outcome of improper protein folding; thus the composition and arrangement of amino acids in the proteins would be a major influencing factor in deciding its aggregation propensity. There is a significant need for a prediction algorithm that would enable the rational identification of both mutants and also the ideal protein candidates for mutations that would confer higher solubility-on-overexpression instead of the presently used trial-and-error procedures. RESULTS: Six physicochemical properties together with residue and dipeptide-compositions have been used to develop a support vector machine-based classifier to predict the overexpression status in E.coli. The prediction accuracy is approximately 72% suggesting that it performs reasonably well in predicting the propensity of a protein to be soluble or to form inclusion bodies. The algorithm could also correctly predict the change in solubility for most of the point mutations reported in literature. This algorithm can be a useful tool in screening protein libraries to identify soluble variants of proteins. 相似文献
634.
635.
Selvaraj R Arunprasath P Karthikeyan B George G Balachander J 《Indian pacing and electrophysiology journal》2010,10(9):426-428
We describe a patient with an implanted pacemaker for impaired AV conduction who presented with an incessant tachycardia. EP study showed that the tachycardia was atrioventricular nodal reentrant tachycardia (AVNRT) with repeated spontaneous initiation because of poor or absent antegrade fast pathway conduction. Slow pathway ablation was successful in terminating the tachycardia and making it non-inducible. 相似文献
636.
Honghe Wan Tram Huynh Suhong Pang Jieping Geng Wayne Vaccaro Michael A. Poss George L. Trainor Matthew V. Lorenzi Marco Gottardis Lata Jayaraman Ashok V. Purandare 《Bioorganic & medicinal chemistry letters》2009,19(17):5063-5066
Hit to Lead optimization and SAR development led to the identification of the potent and selective benzo[d]imidazole inhibitor (17b) of Co-activator Associated Arginine Methyltransferase (CARM1). 相似文献
637.
The fluid mechanics of blood flow in a catheterized curved artery with stenosis is studied through a mathematical analysis. Blood is modelled as an incompressible Newtonian fluid and the flow is assumed to be steady and laminar. An approximate analytic solution to the problem is obtained through a double series perturbation analysis for the case of small curvature and mild stenosis. The effect of catheterization on various physiologically important flow characteristics (i.e. the pressure drop, impedance and the wall shear stress) is studied for different values of the catheter size and Reynolds number of the flow. It is found that all these flow characteristics vary markedly across a stenotic lesion. Also, increase in the catheter size leads to a considerable increase in their magnitudes. These results are used to obtain the estimates of increased pressure drop across an arterial stenosis when a catheter is inserted into it. Our calculations, based on the geometry and flow conditions existing in coronary arteries, suggest that, in the presence of curvature and stenosis, and depending on the value of k (ratio of catheter size to vessel size) ranging from 0.1 to 0.4, the pressure drop increases by a factor ranging from 1.60 to 5.16. But, in the absence of curvature and stenosis, with the same range of catheter size, this increased factor is about 1.74-4.89. These estimates for the increased pressure drop can be used to correct the error involved in the measured pressure gradients using catheters. The combined effects of stenosis and curvature on flow characteristics are also studied in detail. It is found that the effect of stenosis is more dominant than that of the curvature. Due to the combined effect of stenosis, curvature and catheterization, the secondary streamlines are modified in a cross-sectional plane. The insertion of a catheter into the artery leads to the formation of increased number of secondary vortices. 相似文献
638.
Derek L. Englert Michael D. Manson Arul Jayaraman 《Applied and environmental microbiology》2009,75(13):4557-4564
Chemotaxis is the migration of cells in gradients of chemoeffector molecules. Although multiple, competing gradients must often coexist in nature, conventional approaches for investigating bacterial chemotaxis are suboptimal for quantifying migration in response to gradients of multiple signals. In this work, we developed a microfluidic device for generating precise and stable gradients of signaling molecules. We used the device to investigate the effects of individual and combined chemoeffector gradients on Escherichia coli chemotaxis. Laminar flow-based diffusive mixing was used to generate gradients, and the chemotactic responses of cells expressing green fluorescent protein were determined using fluorescence microscopy. Quantification of the migration profiles indicated that E. coli was attracted to the quorum-sensing molecule autoinducer-2 (AI-2) but was repelled from the stationary-phase signal indole. Cells also migrated toward higher concentrations of isatin (indole-2,3-dione), an oxidized derivative of indole. Attraction to AI-2 overcame repulsion by indole in equal, competing gradients. Our data suggest that concentration-dependent interactions between attractant and repellent signals may be important determinants of bacterial colonization of the gut.Bacteria sense chemoeffectors using cell surface receptors (13, 29). Cells constantly monitor the concentration of specific molecules, comparing the current concentration to the concentration detected a few seconds earlier. This comparison determines the net direction of movement (6, 22). Chemotaxis allows bacteria to approach sources of attractant chemicals or to avoid sources of repellent chemicals. Natural habitats for Escherichia coli, such as the gastrointestinal (GI) tract, are typically heterogeneous and contain multiple chemoeffectors with potentially opposing effects. The integrated chemotactic response in such environments is thus likely to be an important factor in bacterial colonization.Conventional approaches for investigating bacterial chemotaxis, such as the swim plate and capillary (1) assays, are not ideal for quantifying bacterial migration. Chemotactic-ring formation in semisolid agar requires metabolizable attractants and is subject to multiple factors, and both it and the traditional capillary assay are poorly designed to investigate repellent taxis. Mao et al. (23) were the first to investigate bacterial taxis in a microfluidic flow cell. In their device, a concentration gradient is formed by the diffusive mixing of two inlet streams. However, the exposure to a fully developed gradient in this device is limited because it takes time for the gradient to develop.Variations of this technique, such as three-channel microfluidic devices (7, 8) in which a linear gradient is generated in the absence of flow or a T-channel device that monitors chemotaxis perpendicular to the direction of fluid flow (18), were developed subsequently. The T-channel system has many of the limitations of the device developed by Mao et al. (23), and nonflow systems, like the capillary assay (1), suffer from a lack of temporal stability of the gradients.Here, we report a flow-based microfluidic chemotaxis device that is coupled to a gradient generator. Bacteria are exposed to precise and temporally stable concentration gradients of chemoeffectors over the length of the microfluidic channel. This device was used to quantify E. coli chemotaxis in response to the canonical chemoeffectors l-aspartate and Ni2+. The device was also used to investigate chemotaxis toward cell-cell communication signals such as autoinducer-2 (AI-2), indole, and isatin that are likely to be present in the in vivo microenvironment in which E. coli is present (e.g., the human GI tract). The data obtained reinforce the idea that concentration-dependent interactions between different chemical signals could be important determinants of bacterial colonization in natural environments. 相似文献
639.
Attempts were made to evaluate intrinsic biological units of growth of teak trees, which were identified as age and size at
inflection point of diameter at breast height. The observations were further utilized in estimating fractal dimension of the
tree crown, which is an important eco-physiological characteristic of the species. A total of 38 teak plantations belonging
to different age groups and site quality classes were selected for estimating the intrinsic units. Altogether, 57 stumps were
identified for gathering information on age and size at inflection point at stump level (10 cm above ground) from the selected
plantations. Photographs of the upper surface of the selected stumps were taken using a digital camera. Counting of annual
rings/ring age and recording the radial distance from pith to each of the annual rings were done directly (visually) by using
Photoshop and CorelDRAW software in a computer. Thus the age and size at inflection point at stump level were estimated. The
values of intrinsic units at breast height level were estimated using allometric relations. The present study revealed that
these units viz., (namely) age and size (diameter) at inflection point were 6 years and 6 cm at stump level, respectively.
The corresponding values at breast-height level were estimated as 8 years and 10.6 cm including the bark. Fractal dimension
was calculated based on the growth parameters, which were estimated through stump analysis. The fractal dimension worked out
to 2.13 for the species. The value of fractal dimension obtained was biologically justifiable considering the light demanding
nature of the species. 相似文献
640.