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   1118篇
  免费   30篇
  国内免费   26篇
电工技术   113篇
综合类   31篇
化学工业   110篇
金属工艺   111篇
机械仪表   56篇
建筑科学   59篇
矿业工程   26篇
能源动力   54篇
轻工业   300篇
水利工程   4篇
石油天然气   13篇
武器工业   1篇
无线电   34篇
一般工业技术   49篇
冶金工业   24篇
原子能技术   29篇
自动化技术   160篇
  2023年   5篇
  2022年   2篇
  2021年   11篇
  2020年   13篇
  2019年   11篇
  2018年   10篇
  2017年   25篇
  2016年   26篇
  2015年   39篇
  2014年   49篇
  2013年   58篇
  2012年   70篇
  2011年   93篇
  2010年   57篇
  2009年   80篇
  2008年   77篇
  2007年   85篇
  2006年   90篇
  2005年   79篇
  2004年   63篇
  2003年   41篇
  2002年   37篇
  2001年   25篇
  2000年   13篇
  1999年   24篇
  1998年   17篇
  1997年   14篇
  1996年   7篇
  1995年   12篇
  1994年   13篇
  1993年   8篇
  1992年   3篇
  1991年   2篇
  1990年   4篇
  1989年   3篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1985年   2篇
  1984年   1篇
  1983年   1篇
  1981年   1篇
排序方式: 共有1174条查询结果,搜索用时 0 毫秒
1.
Storage lipids, triacylglycerols (TAG), and steryl esters (SE), are predominant constituents of lipid droplets (LD) in fungi. In several yeast species, metabolism of TAG and SE is linked to various cellular processes, including cell division, sporulation, apoptosis, response to stress, and lipotoxicity. In addition, TAG are an important source for the generation of value-added lipids for industrial and biomedical applications. The fission yeast Schizosaccharomyces pombe is a widely used unicellular eukaryotic model organism. It is a powerful tractable system used to study various aspects of eukaryotic cellular and molecular biology. However, the knowledge of S. pombe neutral lipids metabolism is quite limited. In this review, we summarize and discuss the current knowledge of the homeostasis of storage lipids and of the role of LD in the fission yeast S. pombe with the aim to stimulate research of lipid metabolism and its connection with other essential cellular processes. We also discuss the advantages and disadvantages of fission yeast in lipid biotechnology and recent achievements in the use of S. pombe in the biotechnological production of valuable lipid compounds.  相似文献   
2.
降低紧密纺色织物浆纱断头的几项措施   总被引:4,自引:1,他引:3  
为了降低紧密纺色织品种的浆纱断头,提高产品质量,分析了该品种在浆纱过程中产生断头的原因,介绍了在操作方面应采取的措施及在工艺方面应注意的问题.通过适当加大干分绞区张力及前浆槽纱线的喂入张力、预烘张力,单独控制前浆槽的浆液粘度,确保回潮率满足工艺要求,有效解决了紧密纺色织品种浆纱断头问题,提高了织轴质量.  相似文献   
3.
M.A. Deyab 《Corrosion Science》2007,49(5):2315-2328
Corrosion behavior of carbon steel in formation water associated crude oil from Egyptian western desert was studied at various concentrations of dodecyl dimethyl ammonium chloride (CS) as a cationic surfactant. Polarization curves indicate that CS has a good inhibition efficiency for carbon steel in formation water and behaves as cathodic inhibitor. The inhibition efficiency was found to increase with increase in CS concentration until reaches a maximum constant value corresponding to the critical micelle concentration of CS and decrease with increase in solution temperature. The adsorption of CS follows the kinetic thermodynamic model and Flory-Huggins isotherm. Thermodynamic parameters obtained indicate that that the presence of the CS increases the activation energy. Polarization and Impedance measurements indicate that the addition of KI has a significant synergistic effect with CS and results in increase the inhibition efficiency of CS in formation water.  相似文献   
4.
PV system sizing using observed time series of solar radiation   总被引:4,自引:0,他引:4  
Sizing represents an important part of photovoltaic system design. This paper describes a sizing procedure based on the observed time series of solar radiation. Using a simple geometrical construction, the sizing curve is determined as a superposition of contributions from individual climatic cycles of low daily solar radiation. Unlike the traditional methods based on loss-of-load probability, the reliability of supply enters in this method through the length of the time series of data used in the analysis. The method thus resembles techniques used in other branches of engineering where extreme values are considered as functions of certain recurrence intervals.  相似文献   
5.
This paper is concerned with the neutral‐delay‐dependent and discrete‐delay‐dependent stability for uncertain neutral systems with mixed delays and norm‐bounded uncertainties. Through constructing a new augmented Lyapunov‐Krasovskii functional and proving its positive definiteness, introducing some slack matrices and using integral inequality, the improved delay‐dependent stability criteria are derived in terms of linear matrix inequalities. Numerical examples are given to illustrate the significant improvement on the conservatism of the delay bound over some existing results. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society  相似文献   
6.
在分析大中型连杆类锻件生产难点的基础上,提出了通过优化锻造工艺方案,设计了切边冲孔校正复合模。提高了带大孔的连杆类锻件的产品质量和生产效率。  相似文献   
7.
玄武岩纤维表面处理及其复合材料界面改性研究   总被引:3,自引:1,他引:3  
为改善玄武岩纤维的织造性能及其复合材料的界面性能,本文采用表面偶联剂结合乳液型浆料上浆的方法对纤维进行表面处理,研究表明,采用乳液型浆料处理后,玄武岩纤维的织造性能得到显著改善,在上浆处理前对纤维进行表面偶联剂处理,可使玄武岩纤维/环氧复合材料的界面性能得到明显提高,从而实现了纤维织造性能与复合材料界面力学性能的共同改善。  相似文献   
8.
探讨了负摩阻力的计算方法及考虑负摩阻力时对桩承载力的验算,对软土层超过15米,上部堆载大或地下水位大幅度下降地区的桩,尤其是端承桩而言,具有较大的工程实际意义。  相似文献   
9.
The corrosion inhibition of neutral red on the corrosion of cold rolled steel in 1.0 M hydrochloric acid (HCl) was studied using weight loss method and potentiodynamic polarization method. Results obtained revealed that neutral red is an effective inhibitor. It was found that the adsorption of neutral red could prevent steel from weight loss and the adsorption accorded with the Langmuir adsorption isotherm. Potentiodynamic polarization studies showed that neutral red mainly acted as a mixed-type inhibitor for steel in 1.0 M hydrochloric acid. Thermodynamic parameters such as adsorption heat, adsorption entropy and adsorption free energy were obtained from experimental data of the temperature studies of the inhibition process at four temperatures ranging from 30 to 45 °C. The most suitable range of inhibitor concentration was discussed. The kinetic data such as apparent activation energies and pre-exponential factors at different concentrations of the inhibitor were calculated, the effect of the apparent activation energies and pre-exponential factors on the corrosion rates of cold rolled steel was discussed. The inhibitive action was satisfactorily explained by using both thermodynamic and kinetic models. Synergism between chloride ion and neutral red was proposed. The results obtained from weight loss and potentiodynamic polarization were in good agreement.  相似文献   
10.
Self-healing protective films were prepared on a zinc electrode previously treated in a Ce(NO3)3 solution by modification with Na3PO4 and Ce(NO3)3. The protective and self-healing abilities of the films were examined by polarization measurements and observation of pit formation after the electrode was scratched with a knife-edge crosswise and immersed in oxygenated 0.5 M NaCl at 30 °C for many hours. Mechanisms of the protective and self-healing activities were discussed using X-ray photoelectron spectroscopy and electron-probe microanalysis. The protective and self-healing abilities of the films prepared on the zinc electrode by treatment in the Ce(NO3)3 solution and modification with Na3PO4 plus Ca(NO3)2, Mg(NO3)2, Zn(NO3)2 or Ce(NO3)3 were summarized.  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