全文获取类型
收费全文 | 4931篇 |
免费 | 875篇 |
国内免费 | 734篇 |
专业分类
电工技术 | 109篇 |
综合类 | 601篇 |
化学工业 | 103篇 |
金属工艺 | 38篇 |
机械仪表 | 136篇 |
建筑科学 | 61篇 |
矿业工程 | 29篇 |
能源动力 | 32篇 |
轻工业 | 55篇 |
水利工程 | 15篇 |
石油天然气 | 53篇 |
武器工业 | 37篇 |
无线电 | 1287篇 |
一般工业技术 | 174篇 |
冶金工业 | 11篇 |
原子能技术 | 51篇 |
自动化技术 | 3748篇 |
出版年
2024年 | 17篇 |
2023年 | 45篇 |
2022年 | 97篇 |
2021年 | 92篇 |
2020年 | 102篇 |
2019年 | 74篇 |
2018年 | 75篇 |
2017年 | 108篇 |
2016年 | 137篇 |
2015年 | 158篇 |
2014年 | 245篇 |
2013年 | 293篇 |
2012年 | 413篇 |
2011年 | 473篇 |
2010年 | 376篇 |
2009年 | 445篇 |
2008年 | 493篇 |
2007年 | 601篇 |
2006年 | 488篇 |
2005年 | 407篇 |
2004年 | 285篇 |
2003年 | 249篇 |
2002年 | 199篇 |
2001年 | 141篇 |
2000年 | 135篇 |
1999年 | 97篇 |
1998年 | 68篇 |
1997年 | 46篇 |
1996年 | 40篇 |
1995年 | 35篇 |
1994年 | 22篇 |
1993年 | 21篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有6540条查询结果,搜索用时 46 毫秒
121.
Directed signature scheme allows only a designated verifier to check the validity of the signature issued to him; and at the time of trouble or if necessary, any third party can verify the signature with the help of the signer or the designated verifier as well. Due to its merits, directed signature scheme is widely used in situations where the receiver’s privacy should be protected. Threshold directed signature is an extension of the standard directed signature, in which several signers may be required to cooperatively sign messages for sharing the responsibility and authority. To the best of our knowledge, threshold directed signature has not been well studied till now. Therefore, in this paper, we would like to formalize the threshold directed signature and its security model, then present a new (t, n) threshold directed signature scheme from bilinear pairings and use the techniques from provable security to analyze its security. 相似文献
122.
Ting-Yi Chang 《Information Sciences》2008,178(17):3426-3434
Recently, Wu et al. proposed a Convertible Multi-Authenticated Encryption (CMAE) scheme, which allows a signing group with multiple signers to generate a multi-authenticated ciphertext signature on the chosen message so that only a designated verifier can recover and verify the message. In case of later dispute, the verifier can convert the multi-authenticated ciphertext signature into an ordinary one that can be verified by anyone. In this study, a CMAE scheme for group communications is proposed. This is presented by first reviewing the concepts of group-oriented encryption schemes and the merits of Wu et al.’s scheme. This shows that not only can a multi-authenticated ciphertext signature be generated by a signing group, but also the message can be recovered and verified by a verifying group with multiple verifiers. The security of the proposed scheme is based solely on the DDH problem, which provides higher security confidence than using the CDH problem in Wu et al.’s CMAE scheme. 相似文献
123.
Huimin Zhao 《Knowledge and Information Systems》2008,15(3):321-334
In real-world classification problems, different types of misclassification errors often have asymmetric costs, thus demanding cost-sensitive learning methods that attempt to minimize average misclassification cost rather than plain error rate. Instance weighting and post hoc threshold adjusting are two major approaches to cost-sensitive classifier learning. This paper compares the effects of these two approaches on several standard, off-the-shelf classification methods. The comparison indicates that the two approaches lead to similar results for some classification methods, such as Naïve Bayes, logistic regression, and backpropagation neural network, but very different results for other methods, such as decision tree, decision table, and decision rule learners. The findings from this research have important implications on the selection of the cost-sensitive classifier learning approach as well as on the interpretation of a recently published finding about the relative performance of Naïve Bayes and decision trees. 相似文献
124.
A residual-based moving block bootstrap procedure for testing the null hypothesis of linear cointegration versus cointegration with threshold effects is proposed. When the regressors and errors of the models are serially and contemporaneously correlated, our test compares favourably with the Sup LM test proposed by Gonzalo and Pitarakis. Indeed, shortcomings of the former motivated the development of our test. The small sample performance of the bootstrap test is investigated by Monte Carlo simulations, and the results show that the test performs better than the Sup LM test. 相似文献
125.
With an increasing acceptance of Wireless Sensor Networks (WSNs), the health of individual sensor is becoming critical in identifying important events in the region of interest. One of the key challenges in detecting event in a WSN is how to detect it accurately transmitting minimum information providing sufficient details about the event. At the same time, it is also important to devise a strategy to handle multiple events occurring simultaneously. In this paper, we propose a Polynomial-based scheme that addresses these problems of Event Region Detection (PERD) by having a aggregation tree of sensor nodes. We employ a data aggregation scheme, TREG (proposed in our earlier work) to perform function approximation of the event using a multivariate polynomial regression. Only coefficients of the polynomial (P) are passed instead of aggregated data. PERD includes two components: event recognition and event report with boundary detection. This can be performed for multiple simultaneously occurring events. We also identify faulty sensor(s) using the aggregation tree. Performing further mathematical operations on the calculated P can identify the maximum (max) and minimum (min) values of the sensed attribute and their locations. Therefore, if any sensor reports a data value outside the [min, max] range, it can be identified as a faulty sensor. Since PERD is implemented over a polynomial tree on a WSN in a distributed manner, it is easily scalable and computation overhead is marginal. Results reveal that event(s) can be detected by PERD with error in detection remaining almost constant achieving a percentage error within a threshold of 10% with increase in communication range. Results also show that a faulty sensor can be detected with an average accuracy of 94% and it increases with increase in node density. 相似文献
126.
127.
128.
129.
130.
传统门户网站单点登录解决方案存在着对原有系统改动大、维护代价高的问题,该文利用反向代理机制实现网站群资源的虚拟集中,结合基于角色的访问控制(RBAC)模型及LDAP技术,设计并实现基于反向代理的单点登录解决方案。该方案不需要对原有系统进行接口编写和改造,具有优良的性能。 相似文献