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   6212篇
  免费   467篇
  国内免费   454篇
化学   3909篇
晶体学   113篇
力学   322篇
综合类   9篇
数学   84篇
物理学   1933篇
无线电   763篇
  2024年   6篇
  2023年   74篇
  2022年   98篇
  2021年   101篇
  2020年   117篇
  2019年   112篇
  2018年   110篇
  2017年   163篇
  2016年   256篇
  2015年   221篇
  2014年   247篇
  2013年   357篇
  2012年   375篇
  2011年   455篇
  2010年   327篇
  2009年   463篇
  2008年   320篇
  2007年   390篇
  2006年   364篇
  2005年   265篇
  2004年   252篇
  2003年   176篇
  2002年   157篇
  2001年   171篇
  2000年   141篇
  1999年   144篇
  1998年   128篇
  1997年   90篇
  1996年   85篇
  1995年   94篇
  1994年   87篇
  1993年   71篇
  1992年   57篇
  1991年   65篇
  1990年   51篇
  1989年   29篇
  1988年   58篇
  1987年   42篇
  1986年   50篇
  1985年   48篇
  1984年   63篇
  1983年   36篇
  1982年   69篇
  1981年   40篇
  1980年   33篇
  1979年   40篇
  1978年   14篇
  1976年   5篇
  1975年   5篇
  1973年   5篇
排序方式: 共有7133条查询结果,搜索用时 62 毫秒
1.
We report on the realization and characterization of electro-responsive and pressure sensitive polydimethylsiloxane (PDMS) conductive photonic structures combined with the reconfigurable properties of short pitch cholesteric liquid crystals (aligned in Grandjean configuration). By combining ion-implantation process and surface chemistry functionalization, we have overcome the insulating properties of PDMS and induced long range organization of cholesteric liquid crystals, thus controlling both diffraction and selective Bragg reflection of light by means of external perturbations (electric field, pressure). We have characterized our devices in terms of morphological, optical and electro-optical properties.  相似文献   
2.
图形点阵式液晶显示器MSP-G320240在高速处理器DSP中的应用   总被引:1,自引:1,他引:0  
介绍了内置SD1335控制器的图形液晶显示器MSP-G320240的工作原理及应用方法,给出了MSP-G320240液晶显示器同DSP的简单接口电路,同时给出了相应的液晶显示器的初始化和清显示区的具体程序。  相似文献   
3.
国产风机盘管空调系统常见问题分析   总被引:2,自引:1,他引:1  
分析了国产风机盘管使用中常见的问题,指出机组因风量不足、冷量风量匹配不合理以及风机盘管某些设备故障,导致了风机盘管精度低、舒适性差、能耗高等一系列问题。指出应引起空调设计和运行维护人员的注意。  相似文献   
4.
激光抛光技术的发展与展望   总被引:8,自引:0,他引:8  
江超  王又青  胡少六 《激光技术》2002,26(6):421-424
介绍激光抛光技术的发展历史,阐明激光抛光的应用现状及未来的发展前景,论述了激光抛光的工艺特点和作用机理,将激光抛光技术与其它抛光技术进行了全面的对比,指出激光抛光的优势及其存在的问题。  相似文献   
5.
Summary A system for capillary electrophoresis combined with enzymatic assay has been evaluated for the two enzymes glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. Instrumentation included a post-column reactor coupled to the separation capillary by a liquid junction. A technique for generating a substrate solution flow into the reactor by utilizing two high voltage supplies is proposed. This method offers a high degree of freedom in optimizing the separation and enzymatic reaction conditions individually. Possibilities for improving the enzymatic assay sensitivity were also examined.  相似文献   
6.
Although coupled liquid chromatographygas chromatography (LC-GC) was first demonstrated ten years ago, only in the last few years has there been a sudden surge of interest in the technique. Approximately 70% of the total number of LC-GC applications have been published in the last two years (1987–88) alone. This review categorizes LC-GC publications into four main application areas: fossil fuels, foods, environmental samples, biologiical/pharmaceutical samples, and miscellaneous samples. Multidimensional separations carried out using other coupled-column chromatographic techniques (such as supercritical fluid chromatography (SFC) with GC, and on-line trace enrichment-GC) have also been included in this review.  相似文献   
7.
讨论了在光纤拉丝生产过程中,影响内涂层直径(POD)的几个重要因素。  相似文献   
8.
This article describes a comprehensive literature review of liquid entrainment in horizontal pipes with vertical-up branches. Deficiencies in the available data and correlations were identified. The Air–water Test Loop for Advanced Thermal–hydraulic Studies (ATLATS) was constructed and entrainment onset and steady-state data were collected for a wide range of flow conditions. Using new insights gained from experimental testing, the authors developed a model for predicting the onset of entrainment and steady-state entrainment rate. Previously published correlations, along with the new model, are compared against all available data. The new model shows very good agreement with the onset data, but is not very good at predicting branch quality at high liquid flow rates.  相似文献   
9.
本文介绍印制板液态感光阻焊油墨的工艺流程、工艺控制,并对生产中较常出现的几种质量问题进行讨论,进而提出解决措施。  相似文献   
10.
Buffer gas beam coolers may become excellent beam preparation devices for high-resolution mass separation. The small beam emittance provided makes efficient isobar resolution a realistic goal. In order to fulfill the needs of future facilities providing high-intensity beams of rare isotopes, it is desirable to increase the beam intensity limit of such devices from typically several tens of nanoamperes to microamperes. This requires the usage of high-voltage radiofrequencies in a low-pressure gas environment. A buffer gas beam cooler, dedicated to this purpose, is under development at the NSCL. The study of voltage breakdowns under such conditions and the design of an electrode system minimizing them is mandatory.   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