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   25505篇
  免费   1563篇
  国内免费   582篇
电工技术   750篇
技术理论   1篇
综合类   642篇
化学工业   4485篇
金属工艺   975篇
机械仪表   1173篇
建筑科学   1296篇
矿业工程   314篇
能源动力   778篇
轻工业   1368篇
水利工程   267篇
石油天然气   571篇
武器工业   49篇
无线电   3982篇
一般工业技术   4175篇
冶金工业   3163篇
原子能技术   266篇
自动化技术   3395篇
  2024年   69篇
  2023年   291篇
  2022年   537篇
  2021年   720篇
  2020年   553篇
  2019年   520篇
  2018年   610篇
  2017年   617篇
  2016年   604篇
  2015年   716篇
  2014年   919篇
  2013年   1550篇
  2012年   1297篇
  2011年   1466篇
  2010年   1182篇
  2009年   1291篇
  2008年   1197篇
  2007年   1154篇
  2006年   1050篇
  2005年   990篇
  2004年   793篇
  2003年   738篇
  2002年   673篇
  2001年   613篇
  2000年   596篇
  1999年   666篇
  1998年   993篇
  1997年   720篇
  1996年   580篇
  1995年   436篇
  1994年   368篇
  1993年   367篇
  1992年   264篇
  1991年   232篇
  1990年   197篇
  1989年   186篇
  1988年   180篇
  1987年   150篇
  1986年   156篇
  1985年   132篇
  1984年   121篇
  1983年   83篇
  1982年   89篇
  1981年   123篇
  1980年   77篇
  1979年   74篇
  1978年   74篇
  1977年   104篇
  1976年   117篇
  1974年   59篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
The Journal of Supercomputing - In the last decade, cloud computing has brought enormous changes to people’s lives. Cloud computing gives a client-driven computational model. In this case,...  相似文献   
12.
13.
14.
15.
This research examined the male and female novice designers toward color associations for the concepts used for ‘warnings’, ‘action required’, and ‘signs and equipment status’ through a questionnaire‐based study. A total of 178 Hong Kong Chinese final year undergraduate design students (89 males and 89 females) participated in the study. The test used required the participants to indicate their choice of one of nine colors to associations with each of 38 concepts in a color‐concept table, so that any one color could be associated with any one of the concepts. For both male and female groups of novice designers, chi‐square tests revealed a strong color association for each concept tested in this study (< .05). The results showed males and females agreed on some color‐concept association stereotypes which were therefore gender neutral. The male and female novice designers had the same color associations and similar levels of stereotype strengths for 21 concepts. The nine strongest and therefore most useful color‐concept association stereotypes for both male and female novice designers were: red‐danger, red‐fire, red‐hot, red‐stop, red‐emergency, red‐error, blue‐cold, blue‐male, and green‐exit. However, the male and female novice designers had different color association stereotypes for the standby (green vs. yellow), emergency exit (green vs. red), and toxic (purple vs. black) concepts, and the strengths of the 14 remaining associations for both groups were not at equivalent levels. Overall, it is anticipated that the findings of this study will act as a useful reference for novice designers and other design practitioners to optimize color coding in the design of ‘warnings’, ‘action required’, and ‘signs and equipment status’ messages.  相似文献   
16.
正Four issues per volume a year,CHINA’S REFRACTORIES is distributed worldwide by airspeed delivery at no extra cost to subscribers.  相似文献   
17.
18.
19.
20.
While perfluoroalkyl acids (PFAAs), also known as C8s, are used extensively in textile repellent coatings, concerns have arisen for their carcinogenicity and hazardous effects on the environment. In this study, a novel water-based, nonfluoro, and nanobrush textile repelling agent was prepared by conventional sol–gel chemistry using amorphous fumed silica and n-octyltriethoxysilane as the starting materials. Minimal interaction between the designed repelling agent and marketed water-based resins was confirmed using linear viscosity region (LVR) analysis and asymmetric-flow field-flow fractionation (AF4), suggesting the self-stratification potential of the repelling agent. More specifically, the repelling agent exhibited excellent compatibility and self-stratifying ability with a force-emulsified acrylic-based resin, affording a water contact angle of 104.3° when incorporated at 7% solid content. Performance tests carried out on thermoplastic polyurethane (TPU) revealed excellent adhesion (100/100) of a final formulation, and a significant increase in water contact angle from 80.1° to 103.8° after treatment. In addition, the fouling area after the removal of a submerged sample from a mixture of slurry, polymer, and oil decreased from 48 to 1% when the repelling agent was added. Moreover, the sludge-fouling property remained unchanged after 1000 cycles of abrasion. These findings demonstrate the potential of the described nonfluoro, nanobrush repelling agent as an environmentally safe alternative for use with commercial resins, in turn realizing a fully water-based hydrophobic coating. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48003.  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