全文获取类型
收费全文 | 61351篇 |
免费 | 7899篇 |
国内免费 | 6097篇 |
专业分类
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 |
出版年
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.
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.
Some picture fuzzy Bonferroni mean operators with their application to multicriteria decision making
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.