首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   552篇
  免费   37篇
  国内免费   1篇
  2024年   2篇
  2023年   4篇
  2022年   10篇
  2021年   47篇
  2020年   16篇
  2019年   15篇
  2018年   13篇
  2017年   9篇
  2016年   18篇
  2015年   29篇
  2014年   32篇
  2013年   43篇
  2012年   42篇
  2011年   36篇
  2010年   37篇
  2009年   23篇
  2008年   24篇
  2007年   32篇
  2006年   23篇
  2005年   15篇
  2004年   21篇
  2003年   15篇
  2002年   11篇
  2001年   9篇
  2000年   4篇
  1999年   6篇
  1998年   6篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1994年   2篇
  1993年   1篇
  1992年   1篇
  1991年   5篇
  1990年   3篇
  1989年   6篇
  1988年   3篇
  1987年   3篇
  1986年   3篇
  1985年   3篇
  1984年   4篇
  1983年   3篇
  1982年   2篇
  1979年   1篇
  1978年   2篇
  1976年   2篇
排序方式: 共有590条查询结果,搜索用时 15 毫秒
581.
Journal of Plant Growth Regulation - Copper (Cu) pollution in agricultural soils is considered as a serious health risk due to its accumulation in plants. Thus, there is an urgent need to optimize...  相似文献   
582.
Phytochemistry Reviews - In recent years the prevalence of diabetes has increased globally and by 2040 the number of diabetic people has been estimated to increase to 642 million. Various classes...  相似文献   
583.
F Georges  M Saleem  A J Cutler 《Gene》1990,91(2):159-165
A synthetic gene coding for the winter flounder antifreeze protein (AFP) has been constructed. A new strategy for the synthesis has been employed such that one strand of the duplex was chemically synthesized and the other was produced enzymatically by chain extension. The chemically synthesized blocks were constructed so that the second strand was self-priming. The resulting DNA fragment was incorporated into the vector, pGCS1, which contained a translational fusion of the sequence encoding AFP and the N terminus of cat (encoding chloramphenicol acetyltransferase, CAT), under the control of the cauliflower mosaic virus 35S promoter. This plasmid was introduced into protoplasts of corn (var. Black Mexican Sweet) by electroporation. Production of the fusion peptide was monitored by CAT assay and Western blotting with antisera to AFP and CAT.  相似文献   
584.
585.
ABSTRACT

This work presents the development and validation of a simple, rapid, and cost-effective spectrophotometric method for quantitative analysis of uric acid in biological samples. The method relies upon uric acid-led reduction of Fe(III) to Fe(II) of sample/standard solutions which stoichiometrically engages ferrozine to form a magenta-colored complex. Different parameters including pH, metal and chelator concentrations, temperature, etc., were optimized for the maximum intensity and stability of the complex. The uric acid concentrations of synthetic/plasma solutions were determined by comparing the color intensity of Fe(ferrozine)3 2+ complex produced by test solution with the standard curve formed by known uric acid concentrations. The method was validated in accordance with ICH guidelines and subjected to human plasma analysis. The results obtained were compared with a reference (enzymatic) method which revealed that there was no significant difference between the two methods at 95% confidence level. The method is highly specific, precise, linear, accurate, and robust.  相似文献   
586.
Electrical interconnects in Data Center Networks (DCNs) suffer from various problems which include high energy consumption, high latency, fixed throughput of links and limited reconfigurability. Introducing optical interconnects in DCNs help to reduce these problems to a large extent. Optical interconnects are the technology of the future. To implement optical switching in DCNs various optical components are used which include wavelength selective switch, tunable wavelength converter, arrayed waveguide grating, semiconductor optical amplifier based switch, wavelength division multiplexers and demultiplexers. All these optical components vary the shape, attenuate the optical signal and introduce time delay in bits. A comprehensive study of various architectures for optical interconnects in data center networks (DCN) is carried out. Performance of various architectures is investigated in terms of jitter, bit error rate (BER), receiver sensitivity and eye diagram opening. It is also investigated how different optical components used in optical interconnects in DCNs are effecting the signal degradation in different architectures. The paper concludes with the categorization of the signal degradation types in optical interconnects in DCNs and ways to reduce them. This enables the design of low BER optical interconnects in DCNs.  相似文献   
587.
When platelet rich plasma is exposed to N-ethylmaleimide, a ten fold increase in measurable prostaglandin E synthesis occurs. This effect is almost completely abolished within 2 hours of ingestion of 600 mg of aspirin by human volunteers. Recovery of this platelet function is slow for the first two days, returning sharply to normal over the next six days and plateauing approximately 8 days following initial removal from aspirin. It is suggested from these studies that platelet prostaglandin E production following NEM may be a useful test of platelet function.  相似文献   
588.

Globally, water resources contaminated with petroleum hydrocarbons are under much consideration due to their hazardous effects on human beings as well as on plants and animals in the ecosystem. Petroleum hydrocarbons are classified as recalcitrant pollutants in nature. These petroleum products are mostly released in the water resources during the petroleum refining process by oil refineries. The conventional clean-up technologies for hydrocarbons contaminated water have more destructive effects on the aquatic and land ecosystems. Consequently, to develop cost-effective and more environment-friendly techniques that clean up the environment and restore the marine ecosystem to its original forms. Keeping in view, this review article explores the detailed information on fabrication, cost-effectiveness, and an overview of innovation of the floating treatment wetlands (FTWs) using plants and bacterial combined functions to remediate the petroleum hydrocarbons contaminated water. The review also discusses the improvement of microbial efficacy for hydrocarbon degradation using FTWs. The review article shows the various applications of FTWs to remove different organic pollutants in petroleum hydrocarbons contaminated water. The review also describes the prospective benefits of FTWs for their multiple uses for removal of hydrocarbons, chemical oxygen demand (COD), biochemical oxygen demand (BOD), phenol, and solids from hydrocarbons contaminated water. This review widely discusses the role of hydrocarbons in degrading bacteria, and wetland plants and the mechanism involved during the remediation process of hydrocarbons in FTWs. It further demonstrates features disturbing the treatment efficiency of FTWs, and finally, it is concluded by successful applications of FTWs and various suggestions for potential future research prospects.

Graphical Abstract
  相似文献   
589.
A product of p-xylene auto-oxidation, p-methylbenzyl hydroperoxide, acts as a very strong reversible inhibitor of the ethanol dehydrogenating activity of horse liver alcohol dehydrogenase. Concentrations of hydroperoxide as low as that of the enzyme active site (about 10(-8) mol.dm-3) in the assay depresses the activity by 50%. Somewhat less potent is benzyl hydroperoxide (derived from toluene) while the (secondary) hydroperoxide derived from ethylbenzene and tert.butyl hydroperoxide and cumyl hydroperoxide do not inhibit HLAD appreciably.  相似文献   
590.
Postendosymbiotic evolution has given rise to proteins that are multiply targeted within the cell. Various mechanisms have been identified to permit the expression of proteins encoding distinct N termini from a single gene. One mechanism involves alternative translation initiation (aTI). We previously showed evidence of aTI activity within the Arabidopsis thaliana organellar DNA polymerase gene POLγ2. Translation initiates at four distinct sites within this gene, two non-AUG, to produce distinct plastid and mitochondrially targeted forms of the protein. To understand the regulation of aTI in higher plants, we used Polγ2 as a model to investigate both cis- and trans-acting features of the process. Here, we show that aTI in Polγ2 and other plant genes involves ribosome scanning dependent on sequence context at the multiple initiation sites to condition specific binding of at least one trans-acting factor essential for site recognition. Multiple active translation initiation sites appear to operate in several plant genes, often to expand protein targeting. In plants, where the mitochondrion and plastid must share a considerable portion of their proteomes and coordinate their functions, leaky ribosome scanning behavior provides adaptive advantage in the evolution of protein dual targeting and translational regulation.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号