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   533058篇
  免费   6083篇
  国内免费   1728篇
电工技术   9597篇
综合类   841篇
化学工业   79708篇
金属工艺   23756篇
机械仪表   18625篇
建筑科学   12212篇
矿业工程   3251篇
能源动力   11925篇
轻工业   43985篇
水利工程   5913篇
石油天然气   10721篇
武器工业   74篇
无线电   58512篇
一般工业技术   107328篇
冶金工业   93604篇
原子能技术   12565篇
自动化技术   48252篇
  2021年   3899篇
  2019年   3729篇
  2018年   12796篇
  2017年   13151篇
  2016年   10465篇
  2015年   4671篇
  2014年   7518篇
  2013年   20622篇
  2012年   14014篇
  2011年   22968篇
  2010年   19144篇
  2009年   19816篇
  2008年   20368篇
  2007年   22041篇
  2006年   13512篇
  2005年   14893篇
  2004年   13479篇
  2003年   12850篇
  2002年   11914篇
  2001年   11392篇
  2000年   10966篇
  1999年   11146篇
  1998年   26558篇
  1997年   18936篇
  1996年   14564篇
  1995年   11293篇
  1994年   10015篇
  1993年   9902篇
  1992年   7429篇
  1991年   6988篇
  1990年   7071篇
  1989年   6959篇
  1988年   6511篇
  1987年   5818篇
  1986年   5851篇
  1985年   6610篇
  1984年   6168篇
  1983年   5681篇
  1982年   5313篇
  1981年   5446篇
  1980年   5320篇
  1979年   5052篇
  1978年   5095篇
  1977年   5654篇
  1976年   7382篇
  1975年   4407篇
  1974年   4236篇
  1973年   4352篇
  1972年   3691篇
  1971年   3347篇
排序方式: 共有10000条查询结果,搜索用时 188 毫秒
51.
At the hydroelectric unit No. 11 of the Nizhnekamsk hydroelectric power plant, the filling wedges of a rotor were investigated by ultrasound in the free st  相似文献   
52.
Theoretical Foundations of Chemical Engineering - The extraction of nitric and oxalic acids by neutral compounds TBP, DBBP, and TBPO have been studied. The optimal conditions of their separation...  相似文献   
53.
Journal of Communications Technology and Electronics - Abstract—The article presents a rigorous numerical solution, using the Wiener–Hopf method, to the problem of plane wave...  相似文献   
54.
Traditionally, in supervised machine learning, (a significant) part of the available data (usually 50%-80%) is used for training and the rest—for validation. In many problems, however, the data are highly imbalanced in regard to different classes or does not have good coverage of the feasible data space which, in turn, creates problems in validation and usage phase. In this paper, we propose a technique for synthesizing feasible and likely data to help balance the classes as well as to boost the performance in terms of confusion matrix as well as overall. The idea, in a nutshell, is to synthesize data samples in close vicinity to the actual data samples specifically for the less represented (minority) classes. This has also implications to the so-called fairness of machine learning. In this paper, we propose a specific method for synthesizing data in a way to balance the classes and boost the performance, especially of the minority classes. It is generic and can be applied to different base algorithms, for example, support vector machines, k-nearest neighbour classifiers deep neural, rule-based classifiers, decision trees, and so forth. The results demonstrated that (a) a significantly more balanced (and fair) classification results can be achieved and (b) that the overall performance as well as the performance per class measured by confusion matrix can be boosted. In addition, this approach can be very valuable for the cases when the number of actual available labelled data is small which itself is one of the problems of the contemporary machine learning.  相似文献   
55.
Journal of Communications Technology and Electronics - Abstract—The two-dimensional diffraction problem of a plane polarized TM-wave on two identical solid silver nanocylinders is considered....  相似文献   
56.
Metallurgical and Materials Transactions B - The process of obtaining titanium tetrachloride (TiCl4) from the quartz-leucoxene concentrate (QLC) from the Yaregskoe oil-titanium field was studied....  相似文献   
57.
The use of field robots can greatly decrease the amount of time, effort, and associated risk compared to if human workers were to carryout certain tasks such as disaster response. However, transportability and reliability remain two main issues for most current robot systems. To address the issue of transportability, we have developed a lightweight modularizable platform named AeroArm. To address the issue of reliability, we utilize a multimodal sensing approach, combining the use of multiple sensors and sensor types, and the use of different detection algorithms, as well as active continuous closed‐loop feedback to accurately estimate the state of the robot with respect to the environment. We used Challenge 2 of the 2017 Mohammed Bin Zayed International Robotics Competition as an example outdoor manipulation task, demonstrating the capabilities of our robot system and approach in achieving reliable performance in the fields, and ranked fifth place internationally in the competition.  相似文献   
58.
59.
60.

Stability constants and formation enthalpies of supramolecular complexes of crown ethers and their cyclic and acyclic analogues are determined on the basis of experimental data obtained by different physicochemical methods in the terms of a general approach developed and implemented in the ChemEqui software package. The established regularities of variation of stability of complexes are discussed as dependent on the ligand structure, nature of the cation, solvent, and anion. The applicability of the suggested method of determining complexation selectivity is shown for multicomponent equilibria in solutions.

  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