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   135857篇
  免费   2800篇
  国内免费   843篇
电工技术   2116篇
综合类   156篇
化学工业   23645篇
金属工艺   4678篇
机械仪表   3886篇
建筑科学   5372篇
矿业工程   783篇
能源动力   3611篇
轻工业   11515篇
水利工程   1456篇
石油天然气   2495篇
武器工业   48篇
无线电   11387篇
一般工业技术   26835篇
冶金工业   22660篇
原子能技术   3044篇
自动化技术   15813篇
  2022年   1308篇
  2021年   2113篇
  2020年   1474篇
  2019年   1728篇
  2018年   2822篇
  2017年   2675篇
  2016年   3130篇
  2015年   2174篇
  2014年   3414篇
  2013年   7554篇
  2012年   5156篇
  2011年   6447篇
  2010年   5133篇
  2009年   5243篇
  2008年   5698篇
  2007年   5441篇
  2006年   4716篇
  2005年   4221篇
  2004年   3791篇
  2003年   3598篇
  2002年   3433篇
  2001年   2824篇
  2000年   2646篇
  1999年   2600篇
  1998年   4956篇
  1997年   3723篇
  1996年   2942篇
  1995年   2446篇
  1994年   2187篇
  1993年   2223篇
  1992年   1761篇
  1991年   1575篇
  1990年   1704篇
  1989年   1692篇
  1988年   1484篇
  1987年   1427篇
  1986年   1389篇
  1985年   1617篇
  1984年   1424篇
  1983年   1276篇
  1982年   1144篇
  1981年   1207篇
  1980年   1089篇
  1979年   1087篇
  1978年   1025篇
  1977年   1170篇
  1976年   1346篇
  1975年   919篇
  1974年   838篇
  1973年   813篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Determined the specific type of sexual functioning deficits and the relationship between global sexual satisfaction and adjustment in 2 related life areas (marital relationship and body image) for 2 groups of cancer patients at high risk for sexual difficulties. The 2 groups included 16 27–67 yr old females with Stage 2 breast cancer and 16 31–65 yr old females with gynecologic cancer. These Ss were compared to 16 healthy female outpatients (controls). Measures included the Sexual Activities scale from the Derogatis Sexual Functioning Inventory, a modified version of the Dyadic Assessment Scale (marital adjustment), a global sexual evaluation, and a body-image scale. Analyses revealed that the aspects of sexual functioning for breast-cancer and gynecologic-cancer Ss that differed from those of controls were the frequency of sexual behaviors and the level of sexual arousal. Whereas Ss' evaluations of their current sexual life had no relationship to their marital-adjustment ratings, analyses suggested that body-image disruption may be a prevalent problem for gynecologic cancer patients. Data suggest that cancer diagnosis and treatment are instrumental in producing reductions in sexual activity and arousability. (34 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
83.
Oxygen injection has been proposed and experimentally demonstrated as an effective control measure for limiting the rate of heat release and altering the rate of polymerization in emulsion processes. A detailed mathematical model has been previously developed to describe the system behavior with and without oxygen injection. A simple lab scale apparatus was constructed and run extensively. Only trace quantities of oxygen are needed to inhibit the reaction completely. The facile response makes this method attractive for fast temperature control. However, because of the rapid penetration of dissolved oxygen into the polymer particles, growing radical chains are terminated prematurely, lowering product molecular weights. To minimize this detrimental effect, pulsed oxygen control is used and extensive experimental work was performed to determine the effects of controller set points on molecular weight. Moderate oxygen flows and moderate set point temperatures are found to give the optimal response without significant lowering of the final molecular weight. Injected quantities agree well with the order-of-magnitude sparging calculations needed to completely stop initiation. However, complete agreement between model simulations and experimental results was not reached due to an unmeasured loss of monomer from the reactor. Chain transfer to monomer is found to be important in modeling the polymer molecular weight. It has, however, a negligible effect on the reaction rate.  相似文献   
84.
Occupational airway diseases are now receiving attention in industry, although study is hampered by a lack of readily-available data. The interpretation of the data that is available, and also of the root problems themselves, is itself a difficult problem. This paper has been written as a literature review which it is hoped that other researchers can take either as a starting point or as a refresher.  相似文献   
85.
Intense irradiation (25–40 A/cm2) at intermediate energy (400 keV) has been found to cause “metallisation” of tungsten oxide and titanium niobate crystal surfaces. The possible mechanisms and the likely consequences for high-resolution imaging of clean oxide surfaces are briefly discussed.  相似文献   
86.
The synthesis of azo dyes via a conventional aqueous-based diazotisation and coupling reaction requires the use of relatively high concentrations of mineral acids, which leads to high electrolyte concentrations in wastewater. Reported in this paper is an environmentally benign one-pot method for the synthesis of a nonionic azo dye, N,N -diethyl- N -{4-[( E )-(4-nitrophenyl)diazenyl]phenyl}amine, in supercritical carbon dioxide without using a mineral acid. The product yield increased significantly with temperature, with 91% theoretical yield afforded at 80 °C. The pressure of the system had little influence on product yield.  相似文献   
87.
88.
89.
90.
The purpose and current construction status, at the Institute of Theoretical and Experimental Physics, of an experimental electronuclear setup, combining a pulsed proton linear accelerator (36 MeV, 0.5 mA) and a subcritical blanket thermal-power assembly 100 kW, are discussed. The main equipment is already available or is being built in industry. The setup can be used to investigate the dynamics of the interaction of a linac–driver and a subcritical reactor and problems concerning the accelerator–driver and the target–blanket assembly. The proton beams and neutron fluxes will be used for applied purposes. In the future it will be possible to increase substantially the current and energy of the proton beam.  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