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   5052篇
  免费   493篇
  国内免费   4篇
电工技术   65篇
综合类   10篇
化学工业   1435篇
金属工艺   173篇
机械仪表   118篇
建筑科学   143篇
矿业工程   26篇
能源动力   208篇
轻工业   955篇
水利工程   31篇
石油天然气   20篇
无线电   253篇
一般工业技术   1000篇
冶金工业   321篇
原子能技术   12篇
自动化技术   779篇
  2023年   64篇
  2022年   46篇
  2021年   306篇
  2020年   192篇
  2019年   205篇
  2018年   303篇
  2017年   266篇
  2016年   324篇
  2015年   273篇
  2014年   331篇
  2013年   559篇
  2012年   350篇
  2011年   307篇
  2010年   247篇
  2009年   263篇
  2008年   213篇
  2007年   185篇
  2006年   140篇
  2005年   94篇
  2004年   97篇
  2003年   85篇
  2002年   76篇
  2001年   28篇
  2000年   44篇
  1999年   22篇
  1998年   37篇
  1997年   30篇
  1996年   19篇
  1995年   27篇
  1994年   21篇
  1993年   22篇
  1992年   20篇
  1991年   9篇
  1990年   23篇
  1989年   9篇
  1988年   13篇
  1987年   15篇
  1986年   13篇
  1985年   26篇
  1984年   32篇
  1983年   35篇
  1982年   22篇
  1981年   27篇
  1980年   23篇
  1979年   28篇
  1978年   9篇
  1977年   11篇
  1976年   15篇
  1975年   11篇
  1973年   10篇
排序方式: 共有5549条查询结果,搜索用时 31 毫秒
1.
The aim of the present study was to determine mathematical relationships between pH changes in beef 24 h post-slaughter and changes in the intensity of electrical current flowing through bull and heifer carcasses during high-voltage electrical stimulation. The electrical stimulation was applied 40 min postmortem for 120 s. The pH values of m. longissimus thoracis et lumborum were analyzed in the function of electrical current intensity changes and its change during electrical stimulation. Mathematical linear correlations of the y = ax ± b type were demonstrated between pH values at 2, 6, and 24 h postmortem and the initial (Ii) and ultimate (Iu) electrical current intensity values, the difference between them and the initial pH values determined before electrical stimulation. High multiple correlation coefficients (R2 = 0.416, α ≤ 0.001) between Iu and pH values 24 h post-slaughter enabled concluding that there is a possibility to predict a pH value of stimulated carcass with high accuracy, and thus also beef quality, based merely on the ultimate electrical current intensity values.  相似文献   
2.
A hybrid sorbent material for removal of hydrogen sulfide from air was developed. The material is based on activated carbon and iron compounds obtained from waste iron(II) sulfate(VI) heptahydrate. The iron salt is deposited on the carbonaceous support and subjected to oxidation (Fe2+ to Fe3+) using atmospheric oxygen under alkaline conditions. An effect of H2O2 addition to the process on the composition of the resultant material was also examined. X-ray diffraction (XRD) analyses confirmed easy conversion of waste FeSO4·7H2O to iron oxides Fe3O4 and FeOOH. The activated carbon supporting iron oxides revealed a higher efficiency in H2S elimination from air compared to the commercial activated carbon, without any modification.  相似文献   
3.
Multidimensional Systems and Signal Processing - The paper is devoted to the development of the octonion Fourier transform (OFT) theory initiated in 2011 in articles by Hahn and Snopek. It is also...  相似文献   
4.
Metallurgical and Materials Transactions A - The influence of the chemical composition on the crystallization process, amorphous phase formation, and the anticorrosion properties of Al-Zr-Ni-Fe-Y...  相似文献   
5.
The biorelevant PyFALGEA oligopeptide ligand, which is selective towards the epidermal growth factor receptor (EGFR), has been successfully employed as a substrate in magnetic resonance signal amplification by reversible exchange (SABRE) experiments. It is demonstrated that PyFALGEA and the iridium catalyst IMes form a PyFALGEA:IMes molecular complex. The interaction between PyFALGEA:IMes and H2 results in a ternary SABRE complex. Selective 1D EXSY experiments reveal that this complex is labile, which is an essential condition for successful hyperpolarization by SABRE. Polarization transfer from parahydrogen to PyFALGEA is observed leading to significant enhancement of the 1H NMR signals of PyFALGEA. Different iridium catalysts and peptides are inspected to discuss the influence of their molecular structures on the efficiency of hyperpolarization. It is observed that PyFALGEA oligopeptide hyperpolarization is more efficient when an iridium catalyst with a sterically less demanding NHC ligand system such as IMesBn is employed. Experiments with shorter analogues of PyFALGEA, that is, PyLGEA and PyEA, show that the bulky phenylalanine from the PyFALGEA oligopeptide causes steric hindrance in the SABRE complex, which hampers hyperpolarization with IMes. Finally, a single-scan 1H NMR SABRE experiment of PyFALGEA with IMesBn revealed a unique pattern of NMR lines in the hydride region, which can be treated as a fingerprint of this important oligopeptide.  相似文献   
6.
7.
8.
9.
Wireless Personal Communications - For robust monitoring, control and proper energy management of renewable energy sources (RES), wireless sensing networks (WSNs) are proved to be a vital solution....  相似文献   
10.
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