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   5164篇
  免费   48篇
  国内免费   2篇
电工技术   33篇
化学工业   319篇
金属工艺   31篇
机械仪表   21篇
建筑科学   40篇
矿业工程   2篇
能源动力   28篇
轻工业   260篇
水利工程   7篇
石油天然气   3篇
无线电   248篇
一般工业技术   363篇
冶金工业   3576篇
原子能技术   33篇
自动化技术   250篇
  2022年   24篇
  2021年   32篇
  2020年   17篇
  2019年   27篇
  2018年   32篇
  2017年   32篇
  2016年   30篇
  2015年   23篇
  2014年   36篇
  2013年   107篇
  2012年   57篇
  2011年   83篇
  2010年   52篇
  2009年   65篇
  2008年   80篇
  2007年   50篇
  2006年   73篇
  2005年   66篇
  2004年   39篇
  2003年   49篇
  2002年   39篇
  2001年   53篇
  2000年   40篇
  1999年   137篇
  1998年   1028篇
  1997年   622篇
  1996年   399篇
  1995年   226篇
  1994年   209篇
  1993年   255篇
  1992年   74篇
  1991年   57篇
  1990年   73篇
  1989年   71篇
  1988年   76篇
  1987年   63篇
  1986年   55篇
  1985年   55篇
  1984年   23篇
  1983年   24篇
  1982年   34篇
  1981年   36篇
  1980年   52篇
  1978年   28篇
  1977年   94篇
  1976年   226篇
  1975年   33篇
  1973年   16篇
  1972年   15篇
  1970年   14篇
排序方式: 共有5214条查询结果,搜索用时 359 毫秒
71.
72.
73.
We present the first case of esophagogastric devascularization and esophagogastric transection using a stapler through laparoscopic surgery. The procedure was performed in a 71-year-old diabetic woman with alcoholic liver cirrhosis (Child-Pugh B class), portal hypertension, bleeding grade III esophageal varices, and a previous bleeding episode. The surgical technique was carried out without problems, and the patient had an excellent postoperative condition. Esophagogastric devascularization with esophageal transection using a stapler through laparoscopic surgery is a feasible technique that accomplishes the same and all objectives of the open procedure. Operative time in both methods is the same, whereas surgical trauma, inmunologic depletion, amount of transfused blood, pain, use of analgesics, and hospital stay are reduced in the laparoscopic technique.  相似文献   
74.
75.
Ductile phase toughened composites contain phases with significantly different physical properties. Consequently, these phases thin at different rates depending on the sample preparation procedure. A new TEM foil preparation method for the ductile phase toughened Nb-10 a/o Si material has been developed. The method involves chemical thinning in a 70% nitric acid/30% hydrofluoric acid solution followed by electropolishing in a 12.5% sulfuric acid/87.5% methanol electrolyte at -40 degrees C. This procedure for making TEM foils results in large thin areas with the minimum of artifacts. Mechanical grinding of a sample followed by either ion milling, dimpling, or electropolishing produced foils with large electron transparent areas, but with uncharacteristic features of the original Nb-10 a/o Si alloy microstructure. These artifacts were identified as dislocations, surface mottling, and antiphase domains.  相似文献   
76.
77.
78.
79.
Nikhil N. Bhiwankar  R.A. Weiss 《Polymer》2006,47(19):6684-6691
Quaternary ammonium salts of sulfonated polystyrene (SPS) were used as compatibilizers for melt intercalation of PS and pristine Na-montmorillonite. Tetra-octyl ammonium SPS and tetra-decyl ammonium SPS ionomeric compatibilizers produced significant exfoliation and a homogeneous dispersion of the polymer-clay nanocomposites. Wide angle X-ray diffraction and transmission electron microscopy were primarily used to characterize the morphology of the nanocomposites. Image analysis was used to measure the percentage exfoliation. Exfoliation increased with the increasing length of the alkyl chain of the ammonium counter-ion of the SPS ionomer. The nanocomposites containing ionomers exhibited higher storage moduli compared to nanocomposites without the compatibilizer.  相似文献   
80.
The authors describe their perspectives as a psychologist married couple and discuss some of the major trends that have affected their work in the last years, including the women's movement and new developments in the field of psychology. They note both positive and negative changes from the last 2 decades. Whereas there are many more new and exciting opportunities for psychologists today, there are also more pressures, more stringent training and credentialing requirements, more competition, and less mobility. Also discussed are some advantages to being married to another psychologist, including understanding each other's roles, combining social and professional lives, and expanding professional networks. They look to the future of psychology with optimism and hope that by examining and changing some of the restrictions on psychologists today, the field of professional psychology can be made more rewarding for future psychologists. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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