全文获取类型
收费全文 | 32486篇 |
免费 | 2530篇 |
国内免费 | 1435篇 |
专业分类
电工技术 | 1714篇 |
技术理论 | 4篇 |
综合类 | 2272篇 |
化学工业 | 2761篇 |
金属工艺 | 3720篇 |
机械仪表 | 2697篇 |
建筑科学 | 2893篇 |
矿业工程 | 1039篇 |
能源动力 | 716篇 |
轻工业 | 1561篇 |
水利工程 | 904篇 |
石油天然气 | 2211篇 |
武器工业 | 763篇 |
无线电 | 2186篇 |
一般工业技术 | 4931篇 |
冶金工业 | 1290篇 |
原子能技术 | 303篇 |
自动化技术 | 4486篇 |
出版年
2024年 | 86篇 |
2023年 | 346篇 |
2022年 | 569篇 |
2021年 | 811篇 |
2020年 | 837篇 |
2019年 | 686篇 |
2018年 | 724篇 |
2017年 | 960篇 |
2016年 | 1113篇 |
2015年 | 1348篇 |
2014年 | 1984篇 |
2013年 | 2068篇 |
2012年 | 2243篇 |
2011年 | 2476篇 |
2010年 | 2002篇 |
2009年 | 1887篇 |
2008年 | 1883篇 |
2007年 | 2098篇 |
2006年 | 1915篇 |
2005年 | 1650篇 |
2004年 | 1356篇 |
2003年 | 1195篇 |
2002年 | 1035篇 |
2001年 | 934篇 |
2000年 | 765篇 |
1999年 | 649篇 |
1998年 | 535篇 |
1997年 | 392篇 |
1996年 | 378篇 |
1995年 | 301篇 |
1994年 | 254篇 |
1993年 | 172篇 |
1992年 | 155篇 |
1991年 | 124篇 |
1990年 | 114篇 |
1989年 | 64篇 |
1988年 | 52篇 |
1987年 | 25篇 |
1986年 | 18篇 |
1985年 | 35篇 |
1984年 | 27篇 |
1983年 | 35篇 |
1982年 | 33篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 10篇 |
1965年 | 18篇 |
1962年 | 7篇 |
1959年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
传统僵尸程序依赖于集中控制,P2P僵尸的传播和控制方式都是分布式的,使其更具隐蔽性和健壮性.本文通过分析P2P僵尸的特征,对其控制行为进行了较为深入的研究.首先,阐述了控制流相似性的概念并对其做出合理量化;其次,利用皮尔逊序列假设检验法来识别P2P僵尸控制行为;最后,通过自动分类技术来进行二次判定,以完成自动检测.实验和数据分析表明该方法能够有效的识别校园网内P2P僵尸的控制行为,与相关的方法相比,误报显著降低. 相似文献
992.
李梦静 《计算机应用与软件》2011,28(11)
分析测试设计的问题和挑战,结合测试设计和自动化测试的发展,提出基于模型的自动化测试基本思路和解决方案。以TD-RNC的一个特性为例,给出基于该方案的具体实现过程。 相似文献
993.
O. PostolacheAuthor Vitae H. Geirinhas Ramos Author VitaeA. Lopes Ribeiro Author Vitae 《Computer Standards & Interfaces》2011,33(2):191-200
This work presents an eddy-current testing system based on a giant magnetoresistive (GMR) sensing device. Non-destructive tests in aluminum plates are applied in order to extract information about possible defects: cracks, holes and other mechanical damages. Eddy-current testing (ECT) presents major benefits such as low cost, high checking speed, robustness and high sensitivity to large classes of defects. Coil based architecture probes or coil-magnetoresistive probes are usually used in ECT. In our application the GMR sensor is used to detect a magnetic field component parallel to a plate surface, when an excitation field perpendicular to the plate is imposed. A neural network processing architecture, including a multilayer perceptron and a competitive neural network, is used to classify defects using the output amplitude of the eddy-current probe (ECP) and its operation frequency. The crack detection, classification and estimation of the geometrical characteristics, for different classes of defects, are described in the paper. 相似文献
994.
Emelie Engström 《Information and Software Technology》2011,53(1):2-13
Context
Software product lines (SPL) are used in industry to achieve more efficient software development. However, the testing side of SPL is underdeveloped.Objective
This study aims at surveying existing research on SPL testing in order to identify useful approaches and needs for future research.Method
A systematic mapping study is launched to find as much literature as possible, and the 64 papers found are classified with respect to focus, research type and contribution type.Results
A majority of the papers are of proposal research types (64%). System testing is the largest group with respect to research focus (40%), followed by management (23%). Method contributions are in majority.Conclusions
More validation and evaluation research is needed to provide a better foundation for SPL testing. 相似文献995.
Paulo Anselmo da Mota Silveira Neto Ivan do Carmo Machado John D. McGregorEduardo Santana de Almeida Silvio Romero de Lemos Meira 《Information and Software Technology》2011,53(5):407-423
Context
In software development, Testing is an important mechanism both to identify defects and assure that completed products work as specified. This is a common practice in single-system development, and continues to hold in Software Product Lines (SPL). Even though extensive research has been done in the SPL Testing field, it is necessary to assess the current state of research and practice, in order to provide practitioners with evidence that enable fostering its further development.Objective
This paper focuses on Testing in SPL and has the following goals: investigate state-of-the-art testing practices, synthesize available evidence, and identify gaps between required techniques and existing approaches, available in the literature.Method
A systematic mapping study was conducted with a set of nine research questions, in which 120 studies, dated from 1993 to 2009, were evaluated.Results
Although several aspects regarding testing have been covered by single-system development approaches, many cannot be directly applied in the SPL context due to specific issues. In addition, particular aspects regarding SPL are not covered by the existing SPL approaches, and when the aspects are covered, the literature just gives brief overviews. This scenario indicates that additional investigation, empirical and practical, should be performed.Conclusion
The results can help to understand the needs in SPL Testing, by identifying points that still require additional investigation, since important aspects regarding particular points of software product lines have not been addressed yet. 相似文献996.
Context
Input/output transition system (IOTS) models are commonly used when next input can arrive even before outputs are produced. The interaction between the tester and an implementation under test (IUT) is usually assumed to be synchronous. However, as the IUT can produce outputs at any moment, the tester should be prepared to accept all outputs from the IUT, or else be able to block (refuse) outputs of the implementation. Testing distributed, remote applications under the assumptions that communication is synchronous and actions can be blocked is unrealistic, since synchronous communication for such applications can only be achieved if special protocols are used. In this context, asynchronous tests can be more appropriate, reflecting the underlying test architecture which includes queues.Objective
In this paper, we investigate the problem of constructing test cases for given test purposes and specification input/output transition systems, when the communication between the tester and the implementation under test is assumed to be asynchronous, performed via multiple queues.Method
When issuing verdicts, asynchronous tests should take into account a distortion caused by the queues in the observed interactions. First, we investigate how the test purpose can be transformed to account for this distortion when there are a single input queue and a single output queue. Then, we consider a more general problem, when there may be multiple queues.Results
We propose an algorithm which constructs a sound test case, by transforming the test purpose prior to composing it with the specification without queues.Conclusion
The proposed algorithm mitigates the state explosion problem which usually occurs when queues are directly involved in the composition. Experimental results confirm the resulting state space reduction. 相似文献997.
基于改进PSO算法的测试数据自动生成研究 总被引:1,自引:0,他引:1
为了提高软件测试中测试数据自动生成的效率,提出了一种基于改进PSO算法的测试数据自动生成的方法。通过在标准的PSO算法中引入人工免疫的思想,保持了群体的多样性,从而有效避免标准PSO算法易陷入局部最优的问题,提高了算法全局搜索的能力,增强了算法的整体性能。实验结果表明,利用改进后的PSO算法寻找最优解所需的迭代次数和时间明显少于标准粒子群算法,生成测试数据的速度快、效率高。 相似文献
998.
现有的IRC botnet检测技术不适合控制命令交互不频繁的botnet检测。为了实现小规模隐秘僵尸网络的检测,提出了一种基于序列分析的僵尸网络检测模型,对现有的被动检测技术进行补充。讨论了几种探测技术和检测算法,根据客户端响应类型选择检测算法,分析了平均检测轮数,只须观察少量的命令控制交互,能够对单个或多个IRC僵尸主机进行检测。实验结果表明,在保证误报率和漏报率的前提下该方法能在预定检测轮数内完成判定。 相似文献
999.
动态节点质心定位改进算法 总被引:1,自引:0,他引:1
为降低无线传感器网络的定位误差,提高动态节点的定位精度和定位覆盖度,使节点定位能够应用于动态环境下,基于传统的定位算法,提出了一种新的动态节点定位改进算法。该算法通过未知节点接收、保存的分组信息来循环组成虚拟三角形,同时依靠内点测试方法来判断未知节点自身位置,最后根据质心算法来进行最终定位。将仿真结果与传统算法进行比较,结果表明,改进算法可以大大提高无线传感器网络的定位精度和覆盖度。 相似文献
1000.
基于用户运行剖面的软件可靠性测试理论广泛地应用在软件测试领域.然而,这种软件可靠性测试既耗时又昂贵.在国内,现在进行的软件黑盒测试主要是系统测试,对于高可靠性要求的软件,系统测试后也需要评估它的可靠性水平.介绍了一种基于失效分析的软件可靠性评估方法,这种方法利用了软件系统测试后得到的缺陷数据,对每一个缺陷导致失效的内外... 相似文献