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   1482539篇
  免费   27378篇
  国内免费   6953篇
电工技术   34272篇
综合类   6381篇
化学工业   268356篇
金属工艺   63937篇
机械仪表   41385篇
建筑科学   45457篇
矿业工程   11329篇
能源动力   50440篇
轻工业   108724篇
水利工程   14851篇
石油天然气   37436篇
武器工业   132篇
无线电   196260篇
一般工业技术   280354篇
冶金工业   155300篇
原子能技术   33906篇
自动化技术   168350篇
  2021年   15821篇
  2020年   12099篇
  2019年   14833篇
  2018年   15577篇
  2017年   14806篇
  2016年   21251篇
  2015年   17385篇
  2014年   28851篇
  2013年   88084篇
  2012年   34676篇
  2011年   46640篇
  2010年   42027篇
  2009年   50470篇
  2008年   43709篇
  2007年   40562篇
  2006年   43881篇
  2005年   38349篇
  2004年   40768篇
  2003年   40814篇
  2002年   39829篇
  2001年   36722篇
  2000年   35290篇
  1999年   34338篇
  1998年   42648篇
  1997年   37583篇
  1996年   34298篇
  1995年   30158篇
  1994年   28455篇
  1993年   28270篇
  1992年   25939篇
  1991年   23053篇
  1990年   23359篇
  1989年   22436篇
  1988年   20967篇
  1987年   19250篇
  1986年   18621篇
  1985年   21868篇
  1984年   22177篇
  1983年   20167篇
  1982年   19212篇
  1981年   19315篇
  1980年   17897篇
  1979年   18416篇
  1978年   17645篇
  1977年   17325篇
  1976年   18209篇
  1975年   15941篇
  1974年   15444篇
  1973年   15518篇
  1972年   12979篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Theoretical Foundations of Chemical Engineering - On the basis of the classic concepts of the theory of solid-phase combustion, for the first time, a model with a detailed scheme of chemical...  相似文献   
22.
23.
Multimedia Tools and Applications - Recently, many concepts in technology has been changed. According to the digital transformation trends, Internet of Things (IoT) represents an interested...  相似文献   
24.
In this study, dilute chemical bath deposition technique has been used to deposit CdZnS thin films on soda-lime glass substrates. The structural, morphological, optoelectronic properties of as-grown films have been investigated as a function of different Zn2+ precursor concentrations. The X-ray diffractogram of CdS thin-film reveals a peak corresponding to (002) plane with wurtzite structure, and the peak shift has been observed with the increase of the Zn2+ concentration upon formation of CdZnS thin film. From morphological studies, it has been revealed that the diluted chemical bath deposition technique provides homogeneous distribution of film on the substrate even at a lower concentration of Zn2+. Optical characterization has shown that the transparency of the film is influenced by Zn2+ concentration and when the Zn2+ concentration is varied from 0 M to 0.0256 M, bandgap values of resulting films range from 2.42 eV to 3.90 eV while. Furthermore, electrical properties have shown that with increasing zinc concentration the resistivity of the film increases. Finally, numerical simulation validates and suggests that CdZnS buffer layer with composition of 0.0032 M Zn2+ concentration would be a promising candidate in CIGS solar cell.  相似文献   
25.
Combustion, Explosion, and Shock Waves - Results of a numerical study of mixing, ignition, and combustion of a cold hydrogen jet propagating along the lower wall of a channel parallel to a...  相似文献   
26.
Multimedia Tools and Applications - In this work, a new fuzzy logic-based algorithm is proposed for the enhancement of low light color images. A generalization of a fuzzy set known as an...  相似文献   
27.
Multimedia Tools and Applications - Currently, Deep Learning is playing an influential role for Image analysis and object classification. Maize’s diseases reduce production that subsequently...  相似文献   
28.

A large amount of data and applications need to be shared with various parties and stakeholders in the cloud environment for storage, computation, and data utilization. Since a third party operates the cloud platform, owners cannot fully trust this environment. However, it has become a challenge to ensure privacy preservation when sharing data effectively among different parties. This paper proposes a novel model that partitions data into sensitive and non-sensitive parts, injects the noise into sensitive data, and performs classification tasks using k-anonymization, differential privacy, and machine learning approaches. It allows multiple owners to share their data in the cloud environment for various purposes. The model specifies communication protocol among involved multiple untrusted parties to process owners’ data. The proposed model preserves actual data by providing a robust mechanism. The experiments are performed over Heart Disease, Arrhythmia, Hepatitis, Indian-liver-patient, and Framingham datasets for Support Vector Machine, K-Nearest Neighbor, Random Forest, Naive Bayes, and Artificial Neural Network classifiers to compute the efficiency in terms of accuracy, precision, recall, and F1-score of the proposed model. The achieved results provide high accuracy, precision, recall, and F1-score up to 93.75%, 94.11%, 100%, and 87.99% and improvement up to 16%, 29%, 12%, and 11%, respectively, compared to previous works.

  相似文献   
29.
Multimedia Tools and Applications - The three-dimensional models of brain tumors serve as diagnostic assistance for physicians, surgeons, and radiologists. The proposed system establishes an...  相似文献   
30.

We discuss the temperature dependence of a common low temperature local thermometer, a tunnel junction between a superconductor and a normal metal (NIS junction). Towards the lowest temperatures its characteristics tend to saturate, which is usually attributed to selfheating effects. In this technical note, we reanalyze this saturation and show that the temperature independent subgap current of the junction alone explains in some cases the low temperature behavior quantitatively.

  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