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   96268篇
  免费   1901篇
  国内免费   415篇
电工技术   845篇
综合类   2322篇
化学工业   16437篇
金属工艺   4911篇
机械仪表   3334篇
建筑科学   2616篇
矿业工程   579篇
能源动力   1447篇
轻工业   6726篇
水利工程   1360篇
石油天然气   418篇
无线电   9721篇
一般工业技术   17905篇
冶金工业   3233篇
原子能技术   289篇
自动化技术   26441篇
  2024年   41篇
  2023年   184篇
  2022年   923篇
  2021年   1053篇
  2020年   434篇
  2019年   460篇
  2018年   14836篇
  2017年   13815篇
  2016年   10440篇
  2015年   1051篇
  2014年   828篇
  2013年   1100篇
  2012年   3952篇
  2011年   10299篇
  2010年   8947篇
  2009年   6185篇
  2008年   7338篇
  2007年   8300篇
  2006年   572篇
  2005年   1545篇
  2004年   1412篇
  2003年   1427篇
  2002年   770篇
  2001年   254篇
  2000年   281篇
  1999年   187篇
  1998年   184篇
  1997年   156篇
  1996年   162篇
  1995年   94篇
  1994年   80篇
  1993年   79篇
  1992年   79篇
  1991年   72篇
  1990年   42篇
  1989年   38篇
  1988年   45篇
  1987年   32篇
  1986年   43篇
  1985年   36篇
  1968年   45篇
  1967年   34篇
  1966年   44篇
  1965年   44篇
  1959年   35篇
  1958年   37篇
  1957年   36篇
  1956年   36篇
  1955年   63篇
  1954年   68篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
The purpose of this research was to study the capacity of emulsions containing saturated monoglyceride self‐assembly structures to deliver omega‐3 fatty acids in fresh soft cheese. To this aim, fortified emulsions containing different ratios of milk, saturated monoglycerides (MGs) and cod liver oil were added to milk before cheese‐making. These emulsions were characterised by distinct microstructural features observed by polarised light microscopy and apparent viscosity values. The omega‐3 delivery performance of MG emulsions highlighted that this strategy allowed a good retention of the omega‐3‐rich oil in the curd (up to 75%). The fortified cheeses showed yield value and fat content higher than those of control samples. The enriched cheese showed hardness and cohesiveness obtained by texture profile analysis similar to those of the unfortified product. Only a slight decrease in gumminess was detected in fortified cheese.  相似文献   
3.
4.
Mobile software applications have to cope with a particular environment that involves small size, limited resources, high autonomy requirements, competitive business models and many other challenges. To provide development guidelines that respond to these needs, several practices have been introduced; however, it is not clear how these guidelines may contribute to solve the issues present in the mobile domain. Furthermore, the rapid evolution of the mobile ecosystem challenges many of the premises upon which the proposed practices were designed. In this paper, we present a survey of the literature on software assurance practices for mobile applications, with the objective of describing them and assessing their contribution and success. We identified, organized and reviewed a body of research that spans in three levels: software development processes, software product assurance practices, and software implementation practices. By carrying out this literature survey, we reviewed the different approaches that researchers on Software Engineering have provided to address the needs that raise in the mobile software development arena. Moreover, we review the evolution of these practices, identifying how the constant changes and modernization of the mobile execution environment has impacted the methods proposed in the literature. Finally, we introduced discussion on the application of these practices in a real productive setting, opening an area for further research that may determine if practitioners have followed the proposed assurance paradigms.  相似文献   
5.
6.
7.
8.
Variations of Incomplete Open Cubes is the major project by the twentieth-century conceptual artist Sol LeWitt. In this paper we interpret the enumerative component of the project as embeddings of graphs. This formulation permits use of an algorithm to check the completeness of the list of the structures produced by the artist. Our conclusion is that the artist found the correct number of structures (that is, 122), but that his list contains a mistake in the presentation of a pair of incomplete cubes, a discovery that appears not to have been noted before.  相似文献   
9.
10.
Ferrite particles coated with biocompatible phases can be used for hyperthermia treatment of cancer. We have synthesized substituted calcium hexaferrite, which is not stable on its own but is stabilized with small substitution of La. Hexaferrite of chemical composition (CaO)0.75(La203)0.20(Fe2O3)6 was prepared using citrate gel method. Hydroxyapatite was prepared by precipitating it from aqueous solution of Ca(NO3)2 and (NH4)2HPO4 maintaining pH above 11. Four different methods were used for coating of hydroxyapatite on ferrite particles. SEM with EDX and X-ray diffraction analysis shows clear evidence of coating of hydroxyapatite on ferrite particles. These coated ferrite particles exhibited coercive field up to 2 kOe, which could be made useful for hysteresis heating in hyperthermia. Studies by culturing BHK-21 cells and WBC over the samples show evidence of biocompatibility. SEM micrographs and cell counts give clear indication of cell growth on the surface of the sample. Finally coated ferrite particle was implanted in Kasaulli mouse to test its biocompatibility. The magnetic properties and biocompatibility studies show that these hydroxyapatite coated ferrites could be useful for hyperthermia.  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