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   61351篇
  免费   7899篇
  国内免费   6097篇
电工技术   5326篇
技术理论   9篇
综合类   6711篇
化学工业   1416篇
金属工艺   745篇
机械仪表   3761篇
建筑科学   2356篇
矿业工程   1565篇
能源动力   857篇
轻工业   740篇
水利工程   1426篇
石油天然气   2912篇
武器工业   826篇
无线电   9092篇
一般工业技术   3033篇
冶金工业   1168篇
原子能技术   745篇
自动化技术   32659篇
  2024年   276篇
  2023年   809篇
  2022年   1716篇
  2021年   2157篇
  2020年   2260篇
  2019年   1818篇
  2018年   1621篇
  2017年   1968篇
  2016年   2261篇
  2015年   2604篇
  2014年   4131篇
  2013年   3843篇
  2012年   4494篇
  2011年   4895篇
  2010年   3823篇
  2009年   3802篇
  2008年   4281篇
  2007年   4810篇
  2006年   4083篇
  2005年   3664篇
  2004年   3139篇
  2003年   2661篇
  2002年   2021篇
  2001年   1529篇
  2000年   1311篇
  1999年   964篇
  1998年   751篇
  1997年   619篇
  1996年   515篇
  1995年   469篇
  1994年   367篇
  1993年   272篇
  1992年   190篇
  1991年   190篇
  1990年   143篇
  1989年   120篇
  1988年   89篇
  1987年   73篇
  1986年   63篇
  1985年   92篇
  1984年   64篇
  1983年   79篇
  1982年   67篇
  1981年   41篇
  1980年   24篇
  1979年   40篇
  1978年   16篇
  1977年   23篇
  1976年   14篇
  1959年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
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   
12.
By leveraging the secret data coding using the remainder storage based exploiting modification direction (RSBEMD), and the pixel change operation recording based on multi-segment left and right histogram shifting, a novel reversible data hiding (RHD) scheme is proposed in this paper. The secret data are first encoded by some specific pixel change operations to the pixels in groups. After that, multi-segment left and right histogram shifting based on threshold manipulation is implemented for recording the pixel change operations. Furthermore, a multiple embedding policy based on chess board prediction (CBP) and threshold manipulation is put forward, and the threshold can be adjusted to achieve adaptive data hiding. Experimental results and analysis show that it is reversible and can achieve good performance in capacity and imperceptibility compared with the existing methods.  相似文献   
13.
探索采用数据可视化技术分析儿童用品TBT通报数据,以可视化图形图像呈现通报热点并揭示趋势信息,提出对策与建议,助力为儿童用品产业升级、TBT预警数据分析和信息传播工作提供新思路,提高中小企业的国外市场准入机会。  相似文献   
14.
本文以云杉八齿小蠹Ips typographus Linnaeus为例,经标本选取,观察虫体整体形态,绘制整体结构草图,电子显微镜观察局部、得到局部数字图像,分别建立虫体每一部分的高精度细节。把模型每部分拼装在一起组成整体模型,构建出了云杉八齿小蠹三维虚拟昆虫数字化模型。  相似文献   
15.
This paper analyzes the problems existing in the teaching of data structure course, and puts forward the reform from the as- pects of strengthening basic programming, visualized explanation of abstract theory, combination of C++, Java programming, ratio- nal use of online platform, and stratification of exercises, aiming at improving students' practical ability, learning interest and self- confidence.  相似文献   
16.
In the first critical assessment of knowledge economy dynamic paths in Africa and the Middle East, but for a few exceptions, we find overwhelming support for diminishing cross-country disparities in knowledge-based economy dimensions. The paper employs all the four components of the World Bank's Knowledge Economy Index (KEI): economic incentives, innovation, education, and information infrastructure. The main finding suggests that sub-Saharan African (SSA) and the Middle East and North African (MENA) countries with low levels of KE dynamics and catching-up their counterparts of higher KE levels. We provide the speeds of integration and time necessary to achieve full (100%) integration. Policy implications are also discussed.  相似文献   
17.
In this paper, we extend the Bonferroni mean (BM) operator with the picture fuzzy numbers (PFNs) to propose novel picture fuzzy aggregation operators and demonstrate their application to multicriteria decision making (MCDM). On the basis of the algebraic operational rules of PFNs and BM, we introduce some aggregation operators: the picture fuzzy Bonferroni mean, the picture fuzzy normalized weighted Bonferroni mean, and the picture fuzzy ordered weighted Bonferroni mean. Then, a new picture fuzzy MCDM method is proposed with the help of the proposed operators. Lastly, a practical application of proposed model is given to verify the developed model and related results of the proposed model is compared with the results of the existing models to indicate its applicability.  相似文献   
18.
19.
20.
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