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   72840篇
  免费   5341篇
  国内免费   2603篇
电工技术   3625篇
技术理论   10篇
综合类   4103篇
化学工业   12454篇
金属工艺   3859篇
机械仪表   4524篇
建筑科学   6010篇
矿业工程   2023篇
能源动力   2239篇
轻工业   4410篇
水利工程   1110篇
石油天然气   4397篇
武器工业   537篇
无线电   8850篇
一般工业技术   9554篇
冶金工业   3617篇
原子能技术   894篇
自动化技术   8568篇
  2025年   8篇
  2024年   1334篇
  2023年   1392篇
  2022年   1963篇
  2021年   2700篇
  2020年   2318篇
  2019年   2050篇
  2018年   1997篇
  2017年   2300篇
  2016年   2139篇
  2015年   2694篇
  2014年   3286篇
  2013年   3929篇
  2012年   4296篇
  2011年   4532篇
  2010年   3942篇
  2009年   3731篇
  2008年   3662篇
  2007年   3650篇
  2006年   3845篇
  2005年   3330篇
  2004年   2299篇
  2003年   2003篇
  2002年   1932篇
  2001年   1753篇
  2000年   1757篇
  1999年   2029篇
  1998年   1823篇
  1997年   1492篇
  1996年   1422篇
  1995年   1092篇
  1994年   1036篇
  1993年   715篇
  1992年   552篇
  1991年   443篇
  1990年   330篇
  1989年   264篇
  1988年   241篇
  1987年   154篇
  1986年   106篇
  1985年   81篇
  1984年   38篇
  1983年   37篇
  1982年   42篇
  1981年   22篇
  1980年   14篇
  1979年   5篇
  1978年   1篇
  1976年   1篇
  1959年   2篇
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
81.
RADIOIMMUNOTOXICOLOGICALEFFECTOFENRICHEDURANIUMONCENTRALANDPERIPHERALIMMUNECELLSANDTHEPROTECTIVEACTIONOFIL-1ANDIL-2¥ZhuShoupe...  相似文献   
82.
Wang  Lin  Wang  Xin  Li  Tao  Zheng  Ruijuan  Zhu  Junlong  Zhang  Mingchuan 《Neural computing & applications》2023,35(11):8051-8063
Neural Computing and Applications - Adaptive (sub)gradient methods have received wide applications such as the training of deep networks. The square-root regret bounds are achieved in convex...  相似文献   
83.
Zhang  Man  Zhou  Yong  Liu  Bing  Zhao  Jiaqi  Yao  Rui  Shao  Zhiwen  Zhu  Hancheng  Chen  Hao 《Pattern Analysis & Applications》2023,26(2):669-677
Pattern Analysis and Applications - The designed method aims to perform image classification tasks efficiently and accurately. Different from the traditional CNN-based image classification methods,...  相似文献   
84.
Zhu  Ting  Qu  Wen  Cao  Wenliang 《The Journal of supercomputing》2022,78(1):222-237
The Journal of Supercomputing - With the wide spread of image information, it is an urgent problem to protect image property rights and crack down on piracy. Watermarking algorithm is an effective...  相似文献   
85.
Ma  Yuhao  Zhu  Jian  Liu  Jie 《Applied Intelligence》2022,52(7):7700-7712
Applied Intelligence - Implicit discourse relation classification is one of the most challenging tasks in discourse parsing. Without connectives as linguistic clues, classifying discourse relations...  相似文献   
86.
The purpose of this study is to analyze the environmental pollution effects elicited by industrial agglomeration and to devise necessary changes before and after China going into the New Normal, a contemporary phase of less rapid but more sustainable economic development. An empirical model is constructed based on the Copeland–Taylor model, and empirical research is conducted using statistical panel data derived from 285 Chinese cities between 2003 and 2014. To study the relationship between industrial agglomeration and industrial pollutant emission both before and after the ‘New Normal,’ the sample data are divided into two time periods: 2003–2008 and 2009–2014. Estimated results are as follows. First, industrial agglomeration exacerbates industrial pollution levels overall although the negative environmental effect of industrial agglomeration is weakened following China’s entry into the New Normal phase of economy. Second, both the interaction term of industrial agglomeration and foreign direct investment (FDI) and the interaction term of industrial agglomeration and environmental regulation are negatively related to industrial agglomeration. These findings indicate that FDI and environmental regulation can indirectly reduce industrial pollutant emissions by way of industrial agglomeration.  相似文献   
87.
Zhang  Jingfei  Qi  Lijuan  Zhu  Xiaoshu  Yan  Xiaohong  Jia  Yufeng  Xu  Lin  Sun  Dongmei  Tang  Yawen 《Nano Research》2017,10(9):3164-3177

The homogeneous incorporation of heteroatoms into two-dimensional C nanostructures, which leads to an increased chemical reactivity and electrical conductivity as well as enhanced synergistic catalysis as a conductive matrix to disperse and encapsulate active nanocatalysts, is highly attractive and quite challenging. In this study, by using the natural and cheap hydrotropic amino acid proline—which has remarkably high solubility in water and a desirable N content of ~12.2 wt.%—as a C precursor pyrolyzed in the presence of a cubic KCl template, we developed a facile protocol for the large-scale production of N-doped C nanosheets with a hierarchically porous structure in a homogeneous dispersion. With concomitantly encapsulated and evenly spread Fe2O3 nanoparticles surrounded by two protective ultrathin layers of inner Fe3C and outer onion-like C, the resulting N-doped graphitic C nanosheet hybrids (Fe2O3@Fe3C-NGCNs) exhibited a very high Li-storage capacity and excellent rate capability with a reliable and prolonged cycle life. A reversible capacity as high as 857 mAh•g–1 at a current density of 100 mA•g–1 was observed even after 100 cycles. The capacity retention at a current density 10 times higher—1,000 mA•g–1—reached 680 mAh•g–1, which is 79% of that at 100 mA•g–1, indicating that the hybrids are promising as anodes for advanced Li-ion batteries. The results highlight the importance of the heteroatomic dopant modification of the NGCNs host with tailored electronic and crystalline structures for competitive Li-storage features.

  相似文献   
88.
89.
90.
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