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   491394篇
  免费   6272篇
  国内免费   2005篇
电工技术   8881篇
综合类   691篇
化学工业   70384篇
金属工艺   18825篇
机械仪表   14568篇
建筑科学   11662篇
矿业工程   2291篇
能源动力   13054篇
轻工业   40383篇
水利工程   4860篇
石油天然气   8383篇
武器工业   56篇
无线电   61973篇
一般工业技术   97902篇
冶金工业   94261篇
原子能技术   11407篇
自动化技术   40090篇
  2021年   3963篇
  2020年   2965篇
  2019年   3691篇
  2018年   6280篇
  2017年   6374篇
  2016年   6717篇
  2015年   4351篇
  2014年   7620篇
  2013年   21552篇
  2012年   12164篇
  2011年   16841篇
  2010年   13243篇
  2009年   15263篇
  2008年   15964篇
  2007年   15969篇
  2006年   13931篇
  2005年   12707篇
  2004年   12477篇
  2003年   12391篇
  2002年   11815篇
  2001年   12302篇
  2000年   11397篇
  1999年   12188篇
  1998年   31042篇
  1997年   21646篇
  1996年   16579篇
  1995年   12545篇
  1994年   11103篇
  1993年   11148篇
  1992年   7904篇
  1991年   7579篇
  1990年   7352篇
  1989年   7166篇
  1988年   6781篇
  1987年   5943篇
  1986年   5858篇
  1985年   6454篇
  1984年   5949篇
  1983年   5605篇
  1982年   5274篇
  1981年   5170篇
  1980年   5107篇
  1979年   4771篇
  1978年   4645篇
  1977年   5398篇
  1976年   7289篇
  1975年   3921篇
  1974年   3846篇
  1973年   3818篇
  1972年   3287篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
51.
Jori  Popat K.  Jadhav  Vrushali H. 《Catalysis Letters》2022,152(6):1703-1710
Catalysis Letters - A new zirconium based carbonaceous solid acid catalyst Zr@CC-PA with both Lewis and Bronsted acidic sites was prepared by simultaneous carbonization and phosphonation of glucose...  相似文献   
52.
One specific class of non-linear evolution equations, known as the Tzitzéica-type equations, has received great attention from a group of researchers involved in non-linear science. In this article, new exact solutions of the Tzitzéica-type equations arising in non-linear optics, including the Tzitzéica, Dodd–Bullough–Mikhailov and Tzitzéica–Dodd–Bullough equations, are obtained using the expa function method. The integration technique actually suggests a useful and reliable method to extract new exact solutions of a wide range of non-linear evolution equations.  相似文献   
53.
Clean Technologies and Environmental Policy - Food production and consumption is one of the major causes of global environmental degradation. One way to address environmental impacts in the food...  相似文献   
54.
55.
56.
Theoretical Foundations of Chemical Engineering - New research results, as well as those published earlier by the authors, on the synthesis of azo compounds based on nitroanilines obtained by the...  相似文献   
57.
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   
58.
The bromodomain and extra terminal (BET) family of bromodomain-containing proteins (BCPs) have been the subject of extensive research over the past decade, resulting in a plethora of high-quality chemical probes for their tandem bromodomains. In turn, these chemical probes have helped reveal the profound biological role of the BET bromodomains and their role in disease, ultimately leading to a number of molecules in active clinical development. However, the BET subfamily represents just 8/61 of the known human bromodomains, and attention has now expanded to the biological role of the remaining 53 non-BET bromodomains. Rapid growth of this research area has been accompanied by a greater understanding of the requirements for an effective bromodomain chemical probe and has led to a number of new non-BET bromodomain chemical probes being developed. Advances since December 2015 are discussed, highlighting the strengths/caveats of each molecule, and the value they add toward validating the non-BET bromodomains as tractable therapeutic targets.  相似文献   
59.
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   
60.
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   
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