全文获取类型
收费全文 | 3658篇 |
免费 | 193篇 |
国内免费 | 165篇 |
专业分类
电工技术 | 39篇 |
技术理论 | 1篇 |
综合类 | 320篇 |
化学工业 | 93篇 |
金属工艺 | 24篇 |
机械仪表 | 64篇 |
建筑科学 | 244篇 |
矿业工程 | 108篇 |
能源动力 | 34篇 |
轻工业 | 41篇 |
水利工程 | 44篇 |
石油天然气 | 1974篇 |
武器工业 | 8篇 |
无线电 | 113篇 |
一般工业技术 | 95篇 |
冶金工业 | 183篇 |
原子能技术 | 9篇 |
自动化技术 | 622篇 |
出版年
2024年 | 4篇 |
2023年 | 25篇 |
2022年 | 48篇 |
2021年 | 53篇 |
2020年 | 60篇 |
2019年 | 55篇 |
2018年 | 46篇 |
2017年 | 73篇 |
2016年 | 89篇 |
2015年 | 120篇 |
2014年 | 159篇 |
2013年 | 149篇 |
2012年 | 178篇 |
2011年 | 257篇 |
2010年 | 173篇 |
2009年 | 180篇 |
2008年 | 146篇 |
2007年 | 222篇 |
2006年 | 260篇 |
2005年 | 236篇 |
2004年 | 206篇 |
2003年 | 182篇 |
2002年 | 158篇 |
2001年 | 112篇 |
2000年 | 111篇 |
1999年 | 115篇 |
1998年 | 98篇 |
1997年 | 105篇 |
1996年 | 61篇 |
1995年 | 73篇 |
1994年 | 81篇 |
1993年 | 29篇 |
1992年 | 29篇 |
1991年 | 20篇 |
1990年 | 17篇 |
1989年 | 12篇 |
1988年 | 14篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1980年 | 3篇 |
1977年 | 2篇 |
1974年 | 6篇 |
1966年 | 2篇 |
1963年 | 3篇 |
1962年 | 3篇 |
1961年 | 3篇 |
1957年 | 2篇 |
排序方式: 共有4016条查询结果,搜索用时 175 毫秒
71.
72.
73.
74.
Vahid Heydari Fami Tafreshi Ebrahim Ghazisaeedi Haitham Cruickshank Zhili Sun 《中兴通讯技术(英文版)》2014,(2):41-49
Network securityprotocolssuch as IPsechave been used for many years to ensure robust end-to-end communication and are impor-tant in the context of SDN.Despite the widespread installation of IPsec to date,per-packet protection offered by the protocol isnot very compatible with OpenFlow and flow-like behavior.OpenFlow architecture cannot aggregate IPsec-ESP flows in transportmode or tunnel mode because layer-3 information is encrypted and therefore unreadable.In this paper,we propose using the Secu-rity Parameter Index(SPI)of IPsec within the OpenFlow architecture to identify and direct IPsec flows.Thisenables IPsec to con-form to the packet-based behavior of OpenFlow architecture.In addition,by distinguishing between IPsec flows,the architectureis particularly suited to secure group communication. 相似文献
75.
With the continuous improvement of Synthetic Aperture Radar (SAR) resolution,interpreting the small targets like aircraft in SAR images becomes possible and turn out to be a hot spot in SAR application research.However,due to the complexity of SAR imaging mechanism,interpreting targets in SAR images is a tough problem.This paper presents a new aircraft interpretation method based on the joint time-frequency analysis and multi-dimensional contrasting of basic structures.Moreover,SAR data acquisition experiment is designed for interpreting the aircraft.Analyzing the experiment data with our method,the result shows that the proposed method largely makes use of the SAR data information.The reasonable results can provide some auxiliary support for the SAR images manual interpretation. 相似文献
76.
软件测试是软件质量保障的基础,而单元测试是软件测试的重要阶段,单元测试用例的设计是软件测试的重要环节。文章重点结合xx型号嵌入式星载软件的一个模块,详细介绍并论述单元测试的方法。 相似文献
77.
《Information and Software Technology》2014,56(3):294-308
The last decade has seen an increasing focus on addressing security already during the earliest stages of system development, such as requirements determination. Attack trees and misuse cases are established techniques for representing security threats along with their potential mitigations. Previous work has compared attack trees and misuse cases in two experiments with students. The present paper instead presents an experiment where industrial practitioners perform the experimental tasks in their workplace. The industrial experiment confirms a central finding from the student experiments: that attack trees tend to help identifying more threats than misuse cases. It also presents a new result: that misuse cases tend to encourage identification of threats associated with earlier development stages than attack trees. The two techniques should therefore be considered complementary and should be used together in practical requirements work. 相似文献
78.
79.
80.
Existing models of causal induction primarily rely on the contingency between the presence and the absence of a causal candidate and an effect. Yet, classification of observations into these four types of covariation data may not be straightforward because (a) most causal candidates, in real life, are continuous with ambiguous, intermediate values and because (b) effects may unfold after some temporal lag, providing ambiguous contingency information. Although past studies suggested various reasons why ambiguous information may not be used during causal induction, the authors examined whether learners spontaneously use ambiguous information through a process called causal assimilation. In particular, the authors examined whether learners willingly place ambiguous observations into one of the categories relevant to the causal hypothesis, in accordance with their current causal beliefs. In Experiment 1, people's frequency estimates of contingency data reflected that information ambiguous along a continuous quantity dimension was spontaneously categorized and assimilated in a causal induction task. This assimilation process was moderated by the strength of the upheld causal hypothesis (Experiment 2), could alter the overall perception of a causal relationship (Experiment 3), and could occur over temporal sequences (Experiment 4). (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献