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   449026篇
  免费   10848篇
  国内免费   5123篇
电工技术   10719篇
技术理论   9篇
综合类   5259篇
化学工业   62799篇
金属工艺   19810篇
机械仪表   16199篇
建筑科学   14998篇
矿业工程   3679篇
能源动力   11873篇
轻工业   32093篇
水利工程   5018篇
石油天然气   10766篇
武器工业   544篇
无线电   57153篇
一般工业技术   85488篇
冶金工业   78832篇
原子能技术   9474篇
自动化技术   40284篇
  2022年   2913篇
  2021年   5642篇
  2020年   4348篇
  2019年   4581篇
  2018年   6689篇
  2017年   7026篇
  2016年   7125篇
  2015年   6147篇
  2014年   9512篇
  2013年   20849篇
  2012年   14314篇
  2011年   18231篇
  2010年   14882篇
  2009年   16409篇
  2008年   16621篇
  2007年   16795篇
  2006年   15458篇
  2005年   14136篇
  2004年   12571篇
  2003年   11996篇
  2002年   11157篇
  2001年   11390篇
  2000年   11021篇
  1999年   11961篇
  1998年   27241篇
  1997年   19047篇
  1996年   14923篇
  1995年   11061篇
  1994年   9654篇
  1993年   9320篇
  1992年   6411篇
  1991年   6079篇
  1990年   5770篇
  1989年   5508篇
  1988年   5031篇
  1987年   4276篇
  1986年   4291篇
  1985年   4618篇
  1984年   4224篇
  1983年   3863篇
  1982年   3677篇
  1981年   3675篇
  1980年   3539篇
  1979年   3236篇
  1978年   3221篇
  1977年   3650篇
  1976年   4996篇
  1975年   2693篇
  1974年   2624篇
  1973年   2612篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
61.
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   
62.
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   
63.
64.
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   
65.
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   
66.
67.
68.
69.

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   
70.
Lobster krill (Munida genus) represents an under‐valued crustacean frequently caught on European fishing banks. In this work, its sensory, microbiological and biochemical qualities were evaluated during chilled storage. Additionally, the effects of a prestorage antimelanosic treatment consisting of soaking in sodium metabisulphite (SMB) solutions at two different concentrations (0.25% and 0.75%) were also studied. SMB prestorage treatment provided lobster specimens that still exhibited acceptable sensory quality after 10 days of storage, while control specimens were unacceptable at that time. SMB treatment also resulted in a significant (P < 0.05) inhibition of microbial growth, mainly of Enterobacteriaceae, psychrotrophes and proteolytic bacteria. Low lipid oxidation levels were observed for all batches; however, a significantly higher (P < 0.05) retention of polyunsaturated fatty acids was found in SMB‐treated lobster, especially in the 0.75% SMB batch. The results presented here open the way to the potential commercialisation of currently under‐utilised lobster krill as a chilled product.  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