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   2598篇
  免费   63篇
  国内免费   12篇
电工技术   213篇
综合类   2篇
化学工业   457篇
金属工艺   68篇
机械仪表   60篇
建筑科学   61篇
矿业工程   1篇
能源动力   54篇
轻工业   217篇
水利工程   13篇
无线电   276篇
一般工业技术   402篇
冶金工业   567篇
原子能技术   56篇
自动化技术   226篇
  2023年   11篇
  2022年   12篇
  2021年   61篇
  2020年   28篇
  2019年   28篇
  2018年   43篇
  2017年   27篇
  2016年   41篇
  2015年   32篇
  2014年   58篇
  2013年   108篇
  2012年   76篇
  2011年   128篇
  2010年   91篇
  2009年   99篇
  2008年   109篇
  2007年   87篇
  2006年   75篇
  2005年   86篇
  2004年   66篇
  2003年   65篇
  2002年   74篇
  2001年   36篇
  2000年   59篇
  1999年   60篇
  1998年   212篇
  1997年   144篇
  1996年   102篇
  1995年   77篇
  1994年   72篇
  1993年   74篇
  1992年   45篇
  1991年   38篇
  1990年   24篇
  1989年   30篇
  1988年   30篇
  1987年   19篇
  1986年   17篇
  1985年   24篇
  1984年   26篇
  1983年   19篇
  1982年   24篇
  1981年   20篇
  1980年   16篇
  1979年   18篇
  1978年   11篇
  1977年   18篇
  1976年   16篇
  1974年   7篇
  1973年   8篇
排序方式: 共有2673条查询结果,搜索用时 15 毫秒
21.
22.
In coating and gravure printing, an impinging jet nozzle with high thermal efficiency for drying of coated film was developed.

Trial production 0f 40 kinds of nozzle enables to develop a high-performance impinging jet nozzle with heat transfer coefficient 1.5 times larger than that of current slit nozzle, through measurement of heat transfer coefficient, visualizations of air flow and heat transfer, and measuremenu of jet velocity and turbulence distribution. The purpose of the trial production was to expand a range of high heat transfer and promote turbulence compared with the current nozzle.

Paying attention to mass transfer within gravure ink coated film, drying characteristic of the film was analyzed by numerical solution of a set of equations governing the drying process in which concentration dependencies 0f the diffusion coefficient and the equilibrium vapor pressure were considered.

Applying these analyses. an industrial scale dryer with excellent drying efficiency has finally been developed.  相似文献   
23.
This paper presents the robust control design of a magnetic suspension system for a flexible beam which is a simplified model of an elastic rotor in a magnetic bearing system. To stabilize this magnetic suspension system which is unstable in nature, the Hinfin; control theory is applied for a design of the control system. To apply the Hinfin; control theory, a statespace model of an augmented plant with frequency-weighting functions is constructed. This augmented plant has two inputs which are the exogenous inputs and the control inputs, and two outputs which are the sensor outputs and the regulated outputs. Here we consider the mixed sensitivity problem. The Hinfin; controller is implemented by a digital controller which is able to execute the computations very quickly. For the evaluation of the control performance, several experiments are made. The robustness of the closed-loop system is confirmed by the experimental results. The result of this study is useful for the control design of a magnetic bearing system.  相似文献   
24.
25.
The spectral linewidth of 1.3 ?m monolithic integrated-passive-cavity (IPC) semiconductor laser is measured by a delayed self-heterodyne technique. It is found that the line-width is narrowed when longitudinal submode is suppressed. The narrowest linewidth obtained so far is 900 kHz at 6 mW output power.  相似文献   
26.
Starting from an effective action for the order parameter field, we derive a coupled set of generalized hydrodynamic equations for a Bose condensate in an optical lattice at finite temperatures. Using the linearized hydrodynamic equations, we study the microscopic mechanism of the Landau instability due to the collisional damping process between the condensate and noncondensate atoms. It is shown that the Landau criterion for the stability of a superfluid in a uniform system is modified due to the presence of the periodic optical lattice potential.  相似文献   
27.
This paper introduces a new family of low-power and high-performance flip-flops, namely conditional data mapping flip-flops (CDMFFs), which reduce their dynamic power by mapping their inputs to a configuration that eliminates redundant internal transitions. We present two CDMFFs, having differential and single-ended structures, respectively, and compare them to the state-of-the-art flip-flops. The results indicate that both CDMFFs have the best power-delay product in their groups, respectively. In the aspect of power dissipation, the single-ended and differential CDMFFs consume the least power at data activity less than 50%, and are 31% and 26% less power than the conditional capture flip-flops at 25% data activity, respectively. In the aspect of performance, CDMFFs achieve small data-to-output delays, comparable to those of the transmission-gate pulsed latch and the modified-sense-amplifier flip-flop. In the aspect of timing reliability, CDMFFs have the best internal race immunity among pulse-triggered flip-flops. A post-layout case study is demonstrated with comparison to a transmission-gate flip-flop. The results indicate the single-ended CDMFF has 34% less in data-to-output delay and 28% less in power at 25% data activity, in spite of the 34% increase in size  相似文献   
28.
29.
Differentiation of endometrial stromal cells (decidualization) is essential for embryo implantation and maintenance of pregnancy. By sequential complementary DNA subtractive hybridization, one of the messenger RNAs (mRNA) induced by progesterone in human endometrial stromal cells decidualized in vitro was identified as that of a tissue transglutaminase type II (TGase). TGase mRNA was induced within 6 h after the addition of progesterone to the culture, and the effect was dose dependent. Both the TGase inhibitor monodansylcadaverine and oligodeoxynucleotide complementary to the TGase mRNA inhibited the decidualization, as assessed by PRL production and morphological transformation. Expression of TGase mRNA in human decidua and endometria exposed to high levels of progesterone in vivo was demonstrated by Northern blotting and in situ hybridization. These data suggest that TGase is necessary for the decidualization of human endometrial stromal cells and that clarification of the mechanism of action of TGase will facilitate further insight into the diagnosis and treatment of infertility.  相似文献   
30.
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