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   140907篇
  免费   20922篇
  国内免费   3272篇
电工技术   5483篇
技术理论   9篇
综合类   5277篇
化学工业   34633篇
金属工艺   5283篇
机械仪表   6631篇
建筑科学   9473篇
矿业工程   2158篇
能源动力   3848篇
轻工业   13662篇
水利工程   1973篇
石油天然气   4690篇
武器工业   516篇
无线电   19140篇
一般工业技术   24418篇
冶金工业   8809篇
原子能技术   994篇
自动化技术   18104篇
  2024年   256篇
  2023年   1336篇
  2022年   2167篇
  2021年   3653篇
  2020年   3858篇
  2019年   5241篇
  2018年   5430篇
  2017年   6020篇
  2016年   6340篇
  2015年   6977篇
  2014年   8128篇
  2013年   10657篇
  2012年   8526篇
  2011年   8638篇
  2010年   8064篇
  2009年   7833篇
  2008年   7140篇
  2007年   6994篇
  2006年   6897篇
  2005年   6041篇
  2004年   4724篇
  2003年   4753篇
  2002年   4748篇
  2001年   4227篇
  2000年   3917篇
  1999年   3534篇
  1998年   3732篇
  1997年   2756篇
  1996年   2375篇
  1995年   1868篇
  1994年   1534篇
  1993年   1232篇
  1992年   850篇
  1991年   700篇
  1990年   556篇
  1989年   500篇
  1988年   443篇
  1987年   281篇
  1986年   272篇
  1985年   256篇
  1984年   177篇
  1983年   152篇
  1982年   139篇
  1981年   154篇
  1980年   136篇
  1979年   93篇
  1977年   134篇
  1976年   208篇
  1975年   66篇
  1973年   63篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
151.
152.
Microsystem Technologies - This paper represents low power and high speed design issues of Hamming code generation and error detection circuit using complementary metal oxide semiconductor (CMOS)...  相似文献   
153.
154.
Metallurgical and Materials Transactions B - Basic oxygen furnace (BOF) steel slag is a main byproduct that is produced during the converter steelmaking process. The volume instability and fast...  相似文献   
155.
We present a distribution‐free tabular cumulative sum chart for monitoring the variability of an autocorrelated process. A quantity known as the asymptotic variance parameter is employed as a measure of the variability, and a distribution‐free tabular cumulative sum chart is applied to variance estimates calculated from batches of nonoverlapping samples. The proposed chart is applicable to a stationary process with a general marginal distribution and a general autocorrelation structure. It also determines control limits analytically without trial‐and‐error simulations. The performance of the proposed chart is tested on stationary processes with both normal and nonnormal marginals with various autocorrelation structures. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
156.
157.
158.
159.
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   
160.
This letter presents a small‐sized, high‐power single‐pole double‐throw (SPDT) switch with defected ground structure (DGS) for wireless broadband Internet application. To reduce the circuit size by using a slow‐wave characteristic, the DGS is used for the quarter‐wave (°/4) transmission line of the switch. To secure a high degree of isolation, the switch with DGS is composed of shunt‐connected PIN diodes. It shows an insertion loss of 0.8 dB, an isolation of 50 dB or more, and power capability of at least 50 W at 2.3 GHz. The switch shows very similar performance to the conventional shunt‐type switch, but the circuit size is reduced by about 50% simply with the use of DGS patterns.  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