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   1543644篇
  免费   27595篇
  国内免费   6986篇
工业技术   1578225篇
  2021年   15422篇
  2020年   11905篇
  2019年   14718篇
  2018年   18606篇
  2017年   18413篇
  2016年   22797篇
  2015年   17587篇
  2014年   28763篇
  2013年   88264篇
  2012年   37541篇
  2011年   52339篇
  2010年   45649篇
  2009年   53568篇
  2008年   48180篇
  2007年   46091篇
  2006年   46118篇
  2005年   42003篇
  2004年   43211篇
  2003年   42885篇
  2002年   41653篇
  2001年   38072篇
  2000年   36409篇
  1999年   35518篇
  1998年   49290篇
  1997年   41663篇
  1996年   34608篇
  1995年   31305篇
  1994年   29108篇
  1993年   28954篇
  1992年   25974篇
  1991年   23202篇
  1990年   23618篇
  1989年   22575篇
  1988年   21088篇
  1987年   19392篇
  1986年   18828篇
  1985年   22191篇
  1984年   22190篇
  1983年   20164篇
  1982年   19110篇
  1981年   19158篇
  1980年   17834篇
  1979年   18368篇
  1978年   17617篇
  1977年   17573篇
  1976年   18731篇
  1975年   15892篇
  1974年   15398篇
  1973年   15500篇
  1972年   13039篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Protection of Metals and Physical Chemistry of Surfaces - The degree of crystallinity of carbon fibers (CFs) of different manufacturers has been determined by means of the Raman scattering method....  相似文献   
992.
Protection of Metals and Physical Chemistry of Surfaces - The inhibiting effect of benzimidazole derivate (DBI) on corrosion of carbon steel (CS) at temperature range of 303–333 K was...  相似文献   
993.
The solvent-dependent polymorphism of the active pharmaceutical ingredient (API) carbamazepine is interpreted from calculations of the solid-state and API-solvent intermolecular interactions. These simulations suggested that apolar solute-solute interactions could be disrupted by apolar solvents. In contrast, the polar solute-solute interactions were found to be easily disrupted by polar and protic solvents. This is consistent with experimental observations that the crystallization of the metastable form II is more dominant in apolar solvents. The Mercury program remains the gold standard in terms of usability; however, further expansion into more complex simulation techniques could make this package of even greater use in pharmaceutical manufacturing workflows.  相似文献   
994.
FeO-doped TiO2 nanoparticle photocatalysts were immobilized onto the surface of fibrous activated carbon (ACF) via a sol-gel process. As an adsorbent and photocatalyst, FeO-TiO2 on immobilized ACFs (FeO-TiO2/ACF) greatly improved the photocatalysis rate of hydrogen production as compared with pure TiO2 and ACF-TiO2 under UV irradiation and visible light. The addition of ACFs surface significantly reduced the photogenerated pairs of electrons-hole recombination, thereby promoting the photocatalysis action of doped photo-metal oxides of FeO-TiO2. Co-doping of FeO onto the lattice of the TiO2 approach can improve the absorption activity of visible light through photo-metal oxide of TiO2 and further enhance hydrogen production under visible light. The photocatalytic fabrics (FeO-TiO2/ACF) were effortlessly split out from the experimental solution for re-utilization and exhibited high stability even after five complete regeneration cycles.  相似文献   
995.
Bakry  A. R.  Hashim  M. D.  Elwy  A. M. 《Radiochemistry》2020,62(3):359-367
Radiochemistry - Leaching of uranium and REEs with oxalic acid from the Egyptian Abu-Tartur phosphate rock (PR) was studied. The effect exerted on the leaching process by oxalic acid concentration,...  相似文献   
996.
Technical Physics Letters - The magnetoelectric (ME) effect in a planar amorphous ferromagnet–piezoelectric lead zirconate titanate (PZT) composite structure can be effectively excited by...  相似文献   
997.
998.
999.
1000.
A new constitutive equation of thermoelasticity for crystals is presented based on the interatomic potential and solid mechanics at finite temperature. Using the new constitutive equation, the calculations for crystal copper and graphene are carried out under different loading paths at different temperatures. The calculated results are in good agreement with those of the previous thermoelasticity constitutive equation based on quantum mechanics, which clearly indicates that our new constitutive equation of thermoelasticity is correct. A lot of comparisons also show that the present theory is more concise and efficient than the previous thermal stress theory in the practical application.  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-23

京公网安备 11010802026262号