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   5738篇
  免费   185篇
  国内免费   3篇
电工技术   66篇
综合类   5篇
化学工业   1221篇
金属工艺   124篇
机械仪表   87篇
建筑科学   254篇
矿业工程   6篇
能源动力   100篇
轻工业   616篇
水利工程   35篇
石油天然气   7篇
武器工业   1篇
无线电   429篇
一般工业技术   1042篇
冶金工业   1349篇
原子能技术   67篇
自动化技术   517篇
  2022年   51篇
  2021年   78篇
  2020年   51篇
  2019年   56篇
  2018年   85篇
  2017年   84篇
  2016年   113篇
  2015年   113篇
  2014年   132篇
  2013年   209篇
  2012年   180篇
  2011年   220篇
  2010年   205篇
  2009年   175篇
  2008年   209篇
  2007年   183篇
  2006年   180篇
  2005年   139篇
  2004年   131篇
  2003年   138篇
  2002年   128篇
  2001年   140篇
  2000年   120篇
  1999年   138篇
  1998年   410篇
  1997年   287篇
  1996年   197篇
  1995年   114篇
  1994年   105篇
  1993年   108篇
  1992年   77篇
  1991年   60篇
  1990年   70篇
  1989年   62篇
  1988年   43篇
  1987年   50篇
  1986年   57篇
  1985年   46篇
  1984年   42篇
  1983年   44篇
  1982年   54篇
  1981年   44篇
  1980年   41篇
  1979年   49篇
  1978年   47篇
  1977年   97篇
  1976年   115篇
  1975年   44篇
  1972年   29篇
  1970年   30篇
排序方式: 共有5926条查询结果,搜索用时 0 毫秒
21.
22.
J. W. Schmidt  W. Heß 《Computing》1987,38(3):261-267
A necessary and sufficient criterion is presented under which the property of positivity carry over from the data set to rational quadratic spline interpolants. The criterion can always be satisfied if the occuring parameters are properly chosen.  相似文献   
23.
以溴和苯基取代的对苯二甲酰氯及2,2′-二甲基联苯-4,4′-二甲酰氯作为单体,分别与甲基、叔丁基、苯基取代的对苯二酚经熔融缩聚反应,合成一类具有刚性棒状结构的全芳香液晶聚酯。聚酯的热性质以TGA、DSC,热台偏光显微镜研究。所有的聚酯均为热致性液晶,它们具有相对较低的转变温度,在普通的有机溶剂中具有较好的溶解性质。  相似文献   
24.
A microbubble-powered bioparticle actuator   总被引:4,自引:0,他引:4  
We present the results of a device that uses controllable microbubble actuation to manipulate bioparticles. In order to create a useful device for controlling the position of bioparticles, predictable microfluidic actuation is crucial. The goal of this project was to develop fundamental technology that can be used to manipulate single bioparticles (e.g., cells). We use a thermal bubble actuation method to accomplish this goal. Microbubbles have the advantages of relatively simple electronics and fabrication but can be difficult to control. In this paper, we describe two specific accomplishments: the use of micromachined nucleation cavities to precisely localize thermal bubbles and to achieve controllable bubble formation temperatures and bubble dissipation and the demonstration of controllable microbubbles in a new device for particle sorting.  相似文献   
25.
The procedure of testing adhesives for glulam production depends in Europe on the kind of resin. For example the testing of phenol-formaldehyde resins (PF-resins) includes the boiling test method, because the curing rate of these resins show a significant correlation between the strength after boiling and the resistance to moisture influence. On the other hand this test method is commonly insufficient for testing other resins. The results of investigations of glulam based on different kinds of resins show that there is a possibility to substitute the boiling test by a short-time accelerated aging method (KZB-Test) which will offer the same differentiation.  相似文献   
26.
27.
Pin&Play: the surface as network medium   总被引:2,自引:0,他引:2  
Integrating appliances in the home through a wired network often proves to be impractical: routing cables is usually difficult, changing the network structure afterward even more so, and portable devices can only be connected at fixed connection points. Wireless networks are not the answer either: batteries have to be regularly replaced or changed, and what they add to the device's size and weight might be disproportionate for smaller appliances. In Pin&Play, we explore a design space in between typical wired and wireless networks, investigating the use of surfaces to network objects that are attached to it. This article gives an overview of the network model, and describes functioning prototypes that were built as a proof of concept.  相似文献   
28.
29.
To determine the most effective treatment for acrodermatitis chronica atrophicans, several clinical trials were undertaken in recent years to evaluate whether a 2-week course of ceftriaxone would be superior to oral antibiotics. Of the 46 patients suffering from acrodermatitis chronica atrophicans, 14 were treated with ceftriaxone 2g for 15 days. The remaining patients received either oral penicillin V 1.5 million IU t.i.d. or doxycycline 100 mg b.i.d. for 20 to 30 days. Patients were followed up for at least 1 year. Of the 14 ceftriaxone-treated patients four showed incomplete regression of the inflammatory skin changes after 6 to 12 months. Two out of five patients who were monitored for Borrelia burgdorferi DNA excretion were still positive after 12 months as compared to none of six patients who were treated orally for 20-30 days. Six out of 11 patients treated orally for only 20 days needed retreatment after 6 months because of continuing skin manifestations, neuropathy or arthralgia. A 30-day duration of treatment with oral antibiotics and not the chosen antibiotic is crucial for curing acrodermatitis chronica atrophicans. The duration of treatment with ceftriaxone needed for eradication of Borrelia in acrodermatitis chronica atrophicans has yet to be determined in future studies.  相似文献   
30.
This study reports the cellular localization of interferon-gamma (IFN-gamma) and MHC class II antigen (Ia) in the spinal cord of rats with experimental autoimmune encephalomyelitis induced by adoptive transfer of myelin basic protein-specific T cells. Numerous IFN-gamma-positive cells, stained with two different monoclonal antibodies against IFN-gamma, were present from days 3 to 7 after cell transfer. Their number was greatly reduced on day 10. A subpopulation of T cells was IFN-gamma positive. Moreover, a large number of ED1-positive macrophages contained IFN-gamma immunoreactivity. The transient presence of immune cells containing IFN-gamma immunoreactivity in experimental autoimmune encephalomyelitis suggests a pathogenic role of this cytokine in immune-mediated demyelination of the central nervous system.  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