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   515858篇
  免费   8078篇
  国内免费   1439篇
工业技术   525375篇
  2021年   4624篇
  2020年   3475篇
  2019年   4554篇
  2018年   7812篇
  2017年   7610篇
  2016年   7933篇
  2015年   5565篇
  2014年   9247篇
  2013年   24087篇
  2012年   14639篇
  2011年   20148篇
  2010年   15806篇
  2009年   17702篇
  2008年   18098篇
  2007年   17783篇
  2006年   15513篇
  2005年   14212篇
  2004年   13591篇
  2003年   13225篇
  2002年   11972篇
  2001年   12093篇
  2000年   10924篇
  1999年   11838篇
  1998年   32150篇
  1997年   22266篇
  1996年   16812篇
  1995年   12928篇
  1994年   11166篇
  1993年   10885篇
  1992年   7813篇
  1991年   7314篇
  1990年   7197篇
  1989年   6887篇
  1988年   6377篇
  1987年   5663篇
  1986年   5579篇
  1985年   6192篇
  1984年   5831篇
  1983年   5100篇
  1982年   4821篇
  1981年   4913篇
  1980年   4658篇
  1979年   4561篇
  1978年   4363篇
  1977年   5283篇
  1976年   6915篇
  1975年   3756篇
  1974年   3509篇
  1973年   3632篇
  1972年   2960篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Journal of Materials Science: Materials in Electronics - Non-volatile organic memory devices were fabricated using polystyrene sulfonate (PSS)?+?nitrogen-doped multi-walled carbon...  相似文献   
2.
Journal of Materials Science: Materials in Electronics - In the recent years, metal oxides have attracted more interest for researchers because of their applications in energy and...  相似文献   
3.
Journal of Engineering Physics and Thermophysics - The generalized nonlocal thermoelastic model in the context of Eringen’s nonlocal elasticity is applied to investigate the...  相似文献   
4.
The present article investigates the influence of Joule heating and chemical reaction on magneto Casson nanofluid phenomena in the occurrence of thermal radiation through a porous inclined stretching sheet. Consideration is extended to heat absorption/generation and viscous dissipation. The governing partial differential equations were transformed into nonlinear ordinary differential equations and numerically solved using the Implicit Finite Difference technique. The article analyses the effect of various physical flow parameters on velocity, heat, and mass transfer distributions. For the various involved parameters, the graphical and numerical outcomes are established. The analysis reveals that the enhancement of the radiation parameter increases the temperature and the chemical reaction parameter decreases the concentration profile. The empirical data presented were compared with previously published findings.  相似文献   
5.
We considered the magnetohydrodynamic (MHD) free convective flow of an incompressible electrically conducting viscous fluid past an infinite vertical permeable porous plate with a uniform transverse magnetic field, heat source and chemical reaction in a rotating frame taking Hall current effects into account. The momentum equations for the fluid flow during absorbent medium are controlled by the Brinkman model. Through the undisturbed state, both the plate and fluid are in a rigid body rotation by the uniform angular velocity perpendicular to an infinite vertical plate. The perpendicular surface is subject to the homogeneous invariable suction at a right angle to it and the heat on the surface varies about a non-zero unvarying average whereas the warmth of complimentary flow is invariable. The systematic solutions of the velocity, temperature, and concentration distributions are acquired systematically by utilizing the perturbation method. The velocity expressions consist of steady-state and fluctuating situations. It is revealed that the steady part of the velocity field has a three-layer characteristic while the oscillatory part of the fluid field exhibits a multi-layer characteristic. The influence of various governing flow parameters on the velocity, temperature, and concentration are analyzed graphically. We also discuss computational results for the skin friction, Nusselt number, and Sherwood number in the tabular forms.  相似文献   
6.
7.
Duparc  Estelle  Möller  Frederik  Jussen  Ilka  Stachon  Maleen  Algac  Sükran  Otto  Boris 《Electronic Markets》2022,32(2):727-745
Electronic Markets - The open-source paradigm offers a plethora of opportunities for innovative business models (BMs) as the underlying codebase of the technology is accessible and extendable by...  相似文献   
8.
Inorganic Materials - We have studied the effect of annealing on the chemical and physical properties of mineral-like host matrices for immobilization of the rare-earth–actinide fraction from...  相似文献   
9.
Semiconductors - The results of the effect of irradiation with Ar ions on the structural, electrophysical, and optical characteristics of ultraviolet Cr/4H-SiC photodetectors in the spectral range...  相似文献   
10.
Chemistry and Technology of Fuels and Oils - This article considers the alternatives for treatment of the raffinate produced at a unit for the extraction of benzene-containing fractions and the...  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