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   1767篇
  免费   111篇
  国内免费   7篇
电工技术   20篇
化学工业   403篇
金属工艺   71篇
机械仪表   29篇
建筑科学   61篇
矿业工程   1篇
能源动力   43篇
轻工业   270篇
水利工程   6篇
石油天然气   2篇
无线电   138篇
一般工业技术   318篇
冶金工业   181篇
原子能技术   5篇
自动化技术   337篇
  2024年   2篇
  2023年   8篇
  2022年   20篇
  2021年   45篇
  2020年   30篇
  2019年   32篇
  2018年   57篇
  2017年   56篇
  2016年   55篇
  2015年   39篇
  2014年   79篇
  2013年   131篇
  2012年   128篇
  2011年   123篇
  2010年   96篇
  2009年   92篇
  2008年   93篇
  2007年   86篇
  2006年   71篇
  2005年   67篇
  2004年   57篇
  2003年   48篇
  2002年   42篇
  2001年   32篇
  2000年   34篇
  1999年   34篇
  1998年   53篇
  1997年   39篇
  1996年   21篇
  1995年   33篇
  1994年   23篇
  1993年   19篇
  1992年   17篇
  1991年   2篇
  1990年   11篇
  1989年   7篇
  1988年   10篇
  1987年   4篇
  1985年   12篇
  1984年   11篇
  1983年   9篇
  1982年   9篇
  1981年   10篇
  1980年   12篇
  1979年   5篇
  1978年   5篇
  1977年   6篇
  1976年   4篇
  1969年   1篇
  1968年   1篇
排序方式: 共有1885条查询结果,搜索用时 15 毫秒
1.
Fan  Deng-Ping  Huang  Ziling  Zheng  Peng  Liu  Hong  Qin  Xuebin  Van Gool  Luc 《国际自动化与计算杂志》2022,19(4):257-287
Machine Intelligence Research - This paper aims to conduct a comprehensive study on facial-sketch synthesis (FSS). However, due to the high cost of obtaining hand-drawn sketch datasets, there is a...  相似文献   
2.
3.
The potential use of stem cell-based therapies for the repair and regeneration of various tissues and organs is a major goal in repair medicine. Stem cells are classified by their potential to differentiate into functional cells. Compared with other sources, adipose-derived stem cells (ADSCs) have the advantage of being abundant and easy to obtain. ADSCs are considered to be tools for replacing, repairing, and regenerating dead or damaged cells. The capacity of ADSCs to maintain their properties depends on the balance of complex signals in their microenvironment. Their properties and the associated outcomes are in part regulated by reactive oxygen species, which mediate the oxidation-reduction state of cells as a secondary messenger. ADSC therapy has demonstrated beneficial effects, suggesting that secreted factors may provide protection. There is evidence that ADSCs secrete a number of cytokines, growth factors, and antioxidant factors into their microenvironment, thus regulating intracellular signaling pathways in neighboring cells. In this review, we introduce the roles of ADSCs in the protection of cells by modulating inflammation and immunity, and we develop their potential therapeutic properties.  相似文献   
4.
5.
6.
The present paper studies a feedback regulation problem that arises in at least two different biological applications. The feedback regulation problem under consideration may be interpreted as an adaptive control problem for tuning bifurcation parameters, and it has not been studied in the control literature. The goal of the paper is to formulate this problem and to present some preliminary results.  相似文献   
7.
8.
We study the transient gratings photogenerated in the picosecond regime in three families of structures, namely : - structures of thickness in the order of one micron, including quantum wells (GaAs/GaAlAs, CdTe/ CdZnTe). A transmission modulation due to the electric field has been observed. We show that, in accordance with our calculations, this modulation is screened faster than 10 ps at a fluence of a few µJ/cm2. - A structure including GalnAs/GalnAsP MQWS in a cavity. This structure shows a top diffraction efficiency of 2.5 × 10-2 at 1.55 µm for an energy of excitation in the order of 100 µJ/cm2. The diffraction efficiency exhibits several oscillations due to Fabry-Pårot effects. By introducing cavity effects in our model, we show that the diffraction efficiency is amplified by more than a factor 2 with respect to the no-cavity case. Calculations show that the diffraction efficiency may reach 6 × 10-2 around 1.625 µm, for a front mirror reflectivity of 90 %. - Structures including bulk GaAs microcavities. The risetime is lower or in the order of 1 ps while the diffraction efficiency attains 1 %, with an average power of 4 mW (i.e. an energy of 2 µJ/cm2/pulse), compatible with a commutation of packets at 80 MHz.  相似文献   
9.
10.
The effect of added oxygen in the range of 1000 to 4000 wt ppm on the microstructures of a Ti-48Al-2Cr-2Nb alloy has been investigated and compared to the microstructures for a high-purity alloy. For specimens cooled from theα phase, interstitial oxygen stabilizes the lamellar microstructure with respect toγ grains, with higher than equilibrium values for theα 2 volume fraction. For specimens cooled from theα +γ phase field, the lamellar microstructure still tends to be favored by oxygen, but it is found that the phase volume fractions are not significantly different from equilibrium values. This suggests that interstitial O essentially reduces the kinetics of theα toα +γ transformation. Thus, interstitial oxygen will have a strong effect on microstructures obtained by continuous cooling fromα, but significantly less on those, such as the duplex microstructure, obtained by long treatment in theα +γ phase field. In general, increased O content is well correlated with reduced ductility. Finally, the role of interstitial oxygen on this phase transformation is discussed.  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