首页 | 官方网站   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   4375篇
  免费   142篇
  国内免费   42篇
工业技术   4559篇
  2023年   18篇
  2022年   23篇
  2021年   83篇
  2020年   35篇
  2019年   60篇
  2018年   86篇
  2017年   63篇
  2016年   74篇
  2015年   79篇
  2014年   103篇
  2013年   220篇
  2012年   177篇
  2011年   266篇
  2010年   235篇
  2009年   259篇
  2008年   258篇
  2007年   224篇
  2006年   184篇
  2005年   199篇
  2004年   126篇
  2003年   143篇
  2002年   148篇
  2001年   100篇
  2000年   95篇
  1999年   82篇
  1998年   201篇
  1997年   141篇
  1996年   128篇
  1995年   81篇
  1994年   73篇
  1993年   88篇
  1992年   50篇
  1991年   49篇
  1990年   33篇
  1989年   29篇
  1988年   38篇
  1987年   37篇
  1986年   25篇
  1985年   49篇
  1984年   32篇
  1983年   31篇
  1982年   18篇
  1981年   29篇
  1980年   18篇
  1979年   11篇
  1977年   12篇
  1976年   17篇
  1975年   6篇
  1974年   4篇
  1972年   5篇
排序方式: 共有4559条查询结果,搜索用时 15 毫秒
31.
32.
33.
Editorial     
  相似文献   
34.
This study describes a process of relating the perceptual analysis of the colors of the terrestrial atmosphere to currently available pigments used in artists' painting systems. This process sought to discover how the colors of the sky could be defined and simulated by these pigments. The author also describes how confusion over the bewildering choice of suitable pigments on offer in the market place can be clarified. © 2006 Wiley Periodicals, Inc. Col Res Appl, 32, 249–255, 2007  相似文献   
35.
This paper presents a feasible study of fully-integrated switching voltage regulators for power-optimized systems-on-chip (SoCs). In order to evaluate the power efficiency across a number of design variables, a compact macro-model of a regulator is created and validated. A key focus of the study is on the characteristics of the active and passive devices that are needed in order to maximize the efficiency of an on-chip regulator. With the macro-model, geometric programming is used to find the optimal characteristics for a given set of constraints such as load condition, process technology, and area. The achievable efficiencies for various current loads and across a range of technologies from 0.35-mum to 90-nm CMOS process are analyzed. The power efficiency is found to be strongly dependent on the inductor technology and over 70% efficiency is possible with advanced inductor technologies.  相似文献   
36.
This article describes a non-contact method for measuring surface velocity and discharge in a natural channel. The X-band pulse (9.36 GHz) radar, developed by the Applied Physics Laboratory of the University of Washington, was used to scan instantaneously the lateral distribution of surface velocity across a river section, according to Bragg scattering from short waves produced by turbulent boils on the surface of the river. Based on the assumption that the vertical velocity distribution follows a universal power or logarithmic law, the discharges were estimated.  相似文献   
37.
MASS TRANSFER IN GAS-SPARGED POROUS ELECTRODES   总被引:1,自引:0,他引:1  
The electrochemical limiting current method was used to measure mass transfer coefficients with cocurrent upward gas-liquid flow in packed bed electrodes. Liquid-solid and overall gas-solid coefficients were determined from limiting current data in the presence of inert or reactive gas flows with the use of a plug flow model. The presence of inert gas flow increased mass transfer coefficients over those in single-phase flow by a factor of up to 1.7. As a result of boundary layer penetration by gas bubbles, sparging with reactive gas increased mass transfer rates by a factor of up to 3.5.  相似文献   
38.
The presence of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) activities was determined in milk and serum of cows with naturally occurring coliform mastitis (CFM). TNF-alpha was detected in the sera from 26 of 32 cows with CFM. TNF-alpha levels were higher in the sera than in the milk. IL-6 was high in the sera of surviving CFM animals, but was low in animals that died and in healthy controls. Furthermore, the mean level of IL-6 was 20-fold higher in the milk than in the sera of mastitic cows. The level of IL-6 in the serum was correlated to that in the milk in individual animals. The presence of IL-6 and TNF-alpha in the sera appears to relate to severe clinical condition of CFM, in the milk whereas they may play a role in generating inflammation of the mammary gland.  相似文献   
39.
40.
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-23

京公网安备 11010802026262号