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   9124篇
  免费   310篇
  国内免费   6篇
电工技术   90篇
综合类   12篇
化学工业   1839篇
金属工艺   135篇
机械仪表   167篇
建筑科学   542篇
矿业工程   18篇
能源动力   218篇
轻工业   687篇
水利工程   74篇
石油天然气   27篇
武器工业   1篇
无线电   524篇
一般工业技术   1687篇
冶金工业   1930篇
原子能技术   126篇
自动化技术   1363篇
  2023年   48篇
  2022年   100篇
  2021年   145篇
  2020年   111篇
  2019年   135篇
  2018年   179篇
  2017年   173篇
  2016年   196篇
  2015年   160篇
  2014年   243篇
  2013年   612篇
  2012年   388篇
  2011年   527篇
  2010年   364篇
  2009年   408篇
  2008年   430篇
  2007年   455篇
  2006年   432篇
  2005年   361篇
  2004年   310篇
  2003年   294篇
  2002年   248篇
  2001年   171篇
  2000年   174篇
  1999年   179篇
  1998年   161篇
  1997年   150篇
  1996年   154篇
  1995年   166篇
  1994年   133篇
  1993年   128篇
  1992年   139篇
  1991年   84篇
  1990年   90篇
  1989年   109篇
  1988年   103篇
  1987年   101篇
  1986年   98篇
  1985年   104篇
  1984年   103篇
  1983年   97篇
  1982年   62篇
  1981年   76篇
  1980年   60篇
  1979年   57篇
  1978年   76篇
  1977年   52篇
  1976年   48篇
  1975年   46篇
  1974年   43篇
排序方式: 共有9440条查询结果,搜索用时 10 毫秒
1.
Removal of gold from basic solutions containing [Au(CN)2]? has been demonstrated using the inherently conducting polymer polypyrrole. Polymers containing sulfonated aromatic dopants have been found to display a significant ability to remove gold from such solutions. Experiments performed in solutions containing both gold and copper cyanide complexes indicate that the recovery process is not highly selective. However, the polypyrroles used display significantly faster rates of gold recovery than activated carbon. © 2003 Society of Chemical Industry  相似文献   
2.
A series of studies of top European and other firms has revealed patterns of design management associated with commercial success. Firms that invest resources and professional expertise in product and industrial design in traditional and new industries have been commercially more successful than firms that pay less attention to these aspects of design. As an industry matures there is a shift in emphasis from design associated with technological innovation, to designs supporting technical improvements, and then to supporting user needs, fashion and product variants. These issues are illustrated through the history of the evolution of the bicycle.  相似文献   
3.
4.
5.
One hypothesis for the transcontinental and intra-Great Lakes basin transfer of round gobies (Neogobius melanostomus) has been that round gobies were pumped into the ballast water of ships. During June 2005 in Lake Erie, we obtained evidence of a vertical migration of round goby larvae, when we collected 167 round goby larvae in surface ichthyoplankton net tows at night and zero during day. These results complemented similar findings from the Muskegon River estuary of Lake Michigan during 2003 and 2004, documenting diel vertical migration for the first time in larval round gobies. We suggest vertical migration behavior may have allowed larval round gobies to be transported to and within the Great Lakes via ballast water and dispersed in the Great Lakes via advection of 6.5–8.5-mm long larvae at the surface. Based on our results, if ballast water was only taken on near the surface during daylight hours from May through September when larval round gobies were present, it would have mitigated the spread of round gobies throughout the Great Lakes.  相似文献   
6.
There are anecdotal reports of color vision deficient medical practitioners (particularly deuteranopes) having difficulty in recognizing cyanosis. An understanding of the color changes in oxygenated blood has led to a better understanding of the lighting needs for hospitals. Using the same database, this article investigates the propensity for color vision deficient observers to make mistakes with cyanotic patients. The possibilities for helping the observer with appropriate color of lighting are considered. The spectral reflectances of blood at varying oxygenation levels previously reported were used 7 ; 8 to calculate chromaticity and lightness. The direction of the chromaticity change was compared with the protanopic and deuteranopic confusion lines. An attempt was made to identify sources that enhanced color changes for the color deficient. The color change of blood oxygenation is closely aligned with the confusion lines of congenital dichromats (particularly protanopia) showing the potential for difficulty in making this decision. No source could be demonstrated to solve the problem or even reduce it significantly. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 428–432, 2007  相似文献   
7.
72 patients engaged in residential drug abuse treatment who also had cognitive impairment were randomly assigned to 1 of 4 groups. One group of patients received 2 hrs of computer-assisted cognitive rehabilitation per week over a 6-mo period; a 2nd group received 2 hrs of progressive muscle relaxation per week over a 6-mo period; a 3rd group was taught typing on a computer; and a 4th group received no treatment beyond that provided by the program. All patients were tested with a neuropsychological test battery at admission and at monthly intervals thereafter for 6 mo. Results show that Ss in the cognitive rehabilitation group demonstrated a faster rate of cognitive recovery during the first 2 mo of treatment and had more efficient cognitive functioning over the first 4 mo of residence. These patients were also rated as more "appropriately participatory" in the treatment program by the clinical staff. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
8.
The adsorption of the three metal ions, copper, cadmium and zinc in single component and multi-component mixtures in aqueous solutions by lignite is reported. A comparison is made between the single component saturation uptake and the multi-component uptakes. The isotherms indicate a competitive uptake with copper being preferentially absorbed by the lignite in multi-component solutions. The isotherms are plotted to obtain the Langmuir constants, the Freundlich constants and the Redlich–Peterson constants. Lignite is shown to possess an affinity for the metal ions which make its use as an adsorbent a possible alternative to the use of more expensive activated carbons.  相似文献   
9.
10.
Review of book: Stephen Mitchell. Can Love Last? The Fate of Romance Over Time. New York: Norton, 2002, 223 pp. Reviewed by Timothy J. Zeddies. (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