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   1030篇
  免费   99篇
  国内免费   2篇
电工技术   7篇
综合类   2篇
化学工业   396篇
金属工艺   22篇
机械仪表   22篇
建筑科学   15篇
矿业工程   1篇
能源动力   42篇
轻工业   119篇
水利工程   17篇
石油天然气   8篇
无线电   73篇
一般工业技术   229篇
冶金工业   22篇
原子能技术   12篇
自动化技术   144篇
  2024年   4篇
  2023年   31篇
  2022年   65篇
  2021年   83篇
  2020年   71篇
  2019年   73篇
  2018年   102篇
  2017年   84篇
  2016年   87篇
  2015年   51篇
  2014年   71篇
  2013年   105篇
  2012年   72篇
  2011年   65篇
  2010年   50篇
  2009年   26篇
  2008年   28篇
  2007年   13篇
  2006年   12篇
  2005年   3篇
  2004年   4篇
  2001年   2篇
  2000年   1篇
  1999年   3篇
  1998年   5篇
  1996年   3篇
  1995年   2篇
  1992年   3篇
  1990年   2篇
  1989年   4篇
  1987年   2篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1978年   1篇
排序方式: 共有1131条查询结果,搜索用时 15 毫秒
1.
Protection of Metals and Physical Chemistry of Surfaces - In this study, the inhibitive performance of 2-mercaptobenzothiazole (2MBT) and 2-aminobenzothiazole (2ABT) were investigated on API-5L X60...  相似文献   
2.
Samani  Saeideh  Vadiati  Meysam  Azizi  Farahnaz  Zamani  Efat  Kisi  Ozgur 《Water Resources Management》2022,36(10):3627-3647
Water Resources Management - Precise estimation of groundwater level (GWL) might be of great importance for attaining sustainable development goals and integrated water resources management....  相似文献   
3.
In this paper, we propose a globally convergent BFGS method to solve Variational Inequality Problems (VIPs). In fact, a globalization technique on the basis of the hyperplane projection method is applied to the BFGS method. The technique, which is independent of any merit function, is applicable for pseudo-monotone problems. The proposed method applies the BFGS direction and tries to reduce the distance of iterates to the solution set. This property, called Fejer monotonicity of iterates with respect to the solution set, is the basis of the convergence analysis. The method applied to pseudo-monotone VIP is globally convergent in the sense that subproblems always have unique solutions, and the sequence of iterates converges to a solution to the problem without any regularity assumption. Finally, some numerical simulations are included to evaluate the efficiency of the proposed algorithm.  相似文献   
4.
A new, efficient and recoverable heterogeneous catalyst was successfully synthesized by functionalization of mesoporous silica FSM-16. The FSM-16/CPTMS-Rh-  相似文献   
5.
6.
Formation of toxic aldehydes in cod liver oil after ultraviolet irradiation   总被引:1,自引:0,他引:1  
Formaldehyde, acrolein, malonaldehyde (MA), acetaldehyde and propanal produced from cod liver oil upon ultraviolet irradiation (λmax=300 nm) were derivatized into nitrogenor sulfur-containing compounds and then analyzed by capillary gas chromatography with a nitrogen-phosphorus detector or a flame photometric detector. Acrolein and MA were formed at levels of 10.9±3.06 and 190.2±38.4 nmol/mg of fish oil, respectively. Maximum levels of formaldehyde, acetaldehyde and propanal formed were 7.0±0.90, 49.1±4.5 and 35.8±4.0 nmol/mg of oil, respectively. Formation of propanal in large quantities corresponded to the high content of ɛ-3 fatty acids in cod liver oil.  相似文献   
7.
8.

The charged particle motion for certain configurations of oscillating magnetic fields can be simulated by a Volterra integro-differential equation of the second order with time-periodic coefficients. This paper investigates a simple and accurate scheme for computationally solving these types of integro-differential equations. To start the method, we first reduce the integro-differential equations to equivalent Volterra integral equations of the second kind. Subsequently, the solution of the mentioned Volterra integral equations is estimated by the collocation method based on the local multiquadrics formulated on scattered points. We also expand the proposed method to solve fractional integro-differential equations including non-integer order derivatives. Since the offered method does not need any mesh generations on the solution domain, it can be recognized as a meshless method. To demonstrate the reliability and efficiency of the new technique, several illustrative examples are given. Moreover, the numerical results confirm that the method developed in the current paper in comparison with the method based on the globally supported multiquadrics has much lesser volume computing.

  相似文献   
9.
A variety of heteropolyanions including: Keggin, Dawson, Preyssler, mixed addenda and sandwich types, catalyzed the formation of 4-methylnaphtho-(1,2-b)-pyran-2-one (coumarin) from the condensation of α-naphthol and ethylacetoacetate in a solvent free system and under heating conditions. Our data vividly indicate that sodium30–tungsto pentaphosphate, [NaP5W30O110]14−, which so-called Preyssler’s anion, with high hydrolytic (pH 0–12) and thermal stability is the catalyst of choice. This catalyst catalyzed the synthesis of other coumarin derivatives in high yields and good selectivity.  相似文献   
10.
Neural Processing Letters - Deep learning is an important subcategory of machine learning approaches in which there is a hope of replacing man-made features with fully automatic extracted features....  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