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   2448篇
  免费   136篇
  国内免费   6篇
电工技术   19篇
综合类   11篇
化学工业   565篇
金属工艺   64篇
机械仪表   48篇
建筑科学   142篇
矿业工程   24篇
能源动力   56篇
轻工业   153篇
水利工程   10篇
无线电   213篇
一般工业技术   533篇
冶金工业   169篇
原子能技术   23篇
自动化技术   560篇
  2023年   31篇
  2022年   43篇
  2021年   72篇
  2020年   67篇
  2019年   56篇
  2018年   70篇
  2017年   57篇
  2016年   84篇
  2015年   84篇
  2014年   84篇
  2013年   201篇
  2012年   170篇
  2011年   189篇
  2010年   149篇
  2009年   152篇
  2008年   161篇
  2007年   136篇
  2006年   116篇
  2005年   96篇
  2004年   68篇
  2003年   71篇
  2002年   54篇
  2001年   35篇
  2000年   28篇
  1999年   49篇
  1998年   36篇
  1997年   25篇
  1996年   23篇
  1995年   18篇
  1994年   17篇
  1993年   21篇
  1992年   19篇
  1991年   10篇
  1990年   13篇
  1989年   11篇
  1988年   7篇
  1987年   7篇
  1986年   5篇
  1985年   4篇
  1984年   8篇
  1983年   7篇
  1981年   4篇
  1980年   3篇
  1977年   4篇
  1976年   2篇
  1973年   2篇
  1972年   3篇
  1971年   3篇
  1970年   4篇
  1960年   2篇
排序方式: 共有2590条查询结果,搜索用时 15 毫秒
131.
Liu S  Volkmer D  Kurth DG 《Analytical chemistry》2004,76(15):4579-4582
An electrochemical sensor design for selective NO detection is presented based on a polyoxometalate (POM) cluster immobilized on an electrode through a polyelectrolyte matrix. It is suggested that the POM can electrocatalyze the reduction of NO. The reduction current is proportional to the NO concentration in the investigated concentration window ranging from 1 nM to 10 microM. The sensitivity of the device can be adjusted by the number of immobilized layers. The response to possible interfering reagents such as nitrate and nitrite can be controlled through the multilayer design. By a predominant negatively charged outer surface, the response to these ions is markedly reduced.  相似文献   
132.
MutS protein plays an important role in the DNA repair system in prokaryotic and eukaryotic cells; it recognizes unpaired and mispaired bases in duplex DNA and can be used for detection of point mutations in vitro. We have shown that small amounts of this protein can be detected electrochemically at mercury and carbon electrodes without any labeling. Using constant current stripping analysis (CPSA) and mercury electrodes, tens of attomoles of this protein can be detected. The sensitivity of the determination at carbon electrodes is by more than 3 orders of magnitude lower. Using biotinylated DNA duplexes attached to magnetic beads, single-base mismatches and insertion/deletions were recognized by MutS. Picogram amounts of this protein were detected by CPSA after MutS releasing from the beads.  相似文献   
133.
A method for the accurate determination of selenoamino acids in human serum by HPLC-ICPMS was developed using the species-specific isotope dilution analysis principle. A serum sample was enzymatically digested with a mixture of lipase and protease after derivatization of the selenocysteine residues with iodoacetamide. The selenoamino acid fraction was isolated by size exclusion LC followed by the separation of selenomethionine and the carboxymethylated selenocysteine by capillary HPLC. The isotope-specific determination of 77Se and 80Se was achieved on-line by ICP collision cell MS allowing the removal of polyatomic interferences. Quantification was carried out by isotope dilution using a 77Se-labeled selenomethionine spike and the determination of the 77Se/80Se ratio in the cHPLC selenomethionine peak. The accurately determined selenomethionine was used as an internal standard for the selenocysteine determination from the same chromatogram. The modification of the previously developed cHPLC-ICPMS interface allowed the reduction of the absolute detection limits twice (down to the 75-fg level), which resulted in the lowest ever reported procedural detection limits (below 0.5 ng g(-1) for a 450-mg serum sample). The precision was less than 5% RSD. The method was validated by the mass balance of selenium (amino acid incorporated vs total).  相似文献   
134.
In the last four decades the container as an essential part of a unit-load-concept has achieved undoubted importance in international sea freight transportation. With ever increasing containerization the number of seaport container terminals and competition among them have become quite remarkable. Operations are nowadays unthinkable without effective and efficient use of information technology as well as appropriate optimization (operations research) methods. In this paper we describe and classify the main logistics processes and operations in container terminals and present a survey of methods for their optimization. Correspondence to: Stefan Voß  相似文献   
135.
136.
137.
Effective screening of large compound libraries in ion channel drug discovery requires the development of new electrophysiological techniques with substantially increased throughputs compared to the conventional patch clamp technique. Sophion Bioscience is aiming to meet this challenge by developing two lines of automated patch clamp products, a traditional pipette-based system called Apatchi-1, and a silicon chip-based system QPatch. The degree of automation spans from semi-automation (Apatchi-1) where a trained technician interacts with the system in a limited way, to a complete automation (QPatch 96) where the system works continuously and unattended until screening of a full compound library is completed. The performance of the systems range from medium to high throughputs.  相似文献   
138.
A sheathless interface based on a total consumption micronebulizer operating at flow rates in the range 0.5-7.5 microL min(-1) was developed between capillary HPLC and ICPMS. It allowed the efficient nebulization and transport into the plasma of mobile phases containing up to 100% organic solvent without either cooling the spray chamber or oxygen addition. The coupled system was applied to selenopeptide mapping in a protein fraction isolated from a selenized yeast extract. The detection limits were 150 (80Se) and 200 fg (82Se) for a quadrupole instrument with and without a collision cell, respectively, which is a factor 100-150 less than that reported elsewhere for HPLC-ICPMS. The minimal peak broadening ( approximately 5 s at the half-height) allowed baseline resolution of a mixture containing more than 30 selenopeptides, many of which could not be separated using the conventional HPLC-ICPMS coupling.  相似文献   
139.
A report from POLYCHAR-10 is provided. An introduction to the following papers presented at the POLYCHAR-10 Forum is given. A small selection of the authors and titles of the papers presented is listed. Prizes awarded are listed along with the composition of the Prize Committee. Some research groups of high activity which are represented at POLYCHAR every year are named. Electronic Publication  相似文献   
140.
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