全文获取类型
收费全文 | 97411篇 |
免费 | 2182篇 |
国内免费 | 879篇 |
专业分类
电工技术 | 1547篇 |
综合类 | 2934篇 |
化学工业 | 13644篇 |
金属工艺 | 5354篇 |
机械仪表 | 3647篇 |
建筑科学 | 3016篇 |
矿业工程 | 772篇 |
能源动力 | 1512篇 |
轻工业 | 4903篇 |
水利工程 | 1515篇 |
石油天然气 | 715篇 |
武器工业 | 87篇 |
无线电 | 11092篇 |
一般工业技术 | 17992篇 |
冶金工业 | 4169篇 |
原子能技术 | 423篇 |
自动化技术 | 27150篇 |
出版年
2024年 | 75篇 |
2023年 | 254篇 |
2022年 | 520篇 |
2021年 | 732篇 |
2020年 | 534篇 |
2019年 | 452篇 |
2018年 | 14848篇 |
2017年 | 13807篇 |
2016年 | 10384篇 |
2015年 | 1161篇 |
2014年 | 926篇 |
2013年 | 1037篇 |
2012年 | 4049篇 |
2011年 | 10384篇 |
2010年 | 8984篇 |
2009年 | 6193篇 |
2008年 | 7429篇 |
2007年 | 8343篇 |
2006年 | 648篇 |
2005年 | 1626篇 |
2004年 | 1448篇 |
2003年 | 1451篇 |
2002年 | 847篇 |
2001年 | 342篇 |
2000年 | 391篇 |
1999年 | 293篇 |
1998年 | 585篇 |
1997年 | 378篇 |
1996年 | 317篇 |
1995年 | 164篇 |
1994年 | 166篇 |
1993年 | 158篇 |
1992年 | 95篇 |
1991年 | 105篇 |
1990年 | 66篇 |
1989年 | 77篇 |
1988年 | 52篇 |
1987年 | 42篇 |
1986年 | 43篇 |
1985年 | 45篇 |
1983年 | 39篇 |
1977年 | 43篇 |
1976年 | 62篇 |
1968年 | 46篇 |
1967年 | 40篇 |
1966年 | 46篇 |
1965年 | 46篇 |
1958年 | 41篇 |
1955年 | 63篇 |
1954年 | 69篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
为研究织物组织结构与复合纱线线密度对织物凉爽性能的影响,将线密度为7.4和9.8 tex涤纶分别与线密度为7.8 tex锦纶反向加捻、并线后作为纬纱,以8.3 tex涤纶/竹浆纤维50/50混纺纱作经纱,设计平纹、二上一下斜纹和透孔组织织物.测试织物的瞬间接触凉感、热湿舒适性能及织物干、湿态升温曲线,并采用凉爽温度指数对织物的综合凉爽性能进行评价.研究结果表明:6种设计织物的瞬间接触凉感均高于标准,且平纹织物最好,纬纱粗细对瞬间接触凉感影响不显著;透孔织物透气性最好,且在人体出汗的状态下具有较好的导湿散热性能.平纹织物凉爽温度指数最高,最大凉爽温度为2.8℃,综合凉爽性能最好. 相似文献
2.
Private information retrieval(PIR) is an important privacy protection issue of secure multi-party computation, but the PIR protocols based on classical cryptography are vulnerable because of new technologies,such as quantum computing and cloud computing. The quantum private queries(QPQ) protocols available, however, has a high complexity and is inefficient in the face of large database. This paper, based on the QKD technology which is mature now, proposes a novel QPQ protocol utilizing the key dilution and auxiliary parameter. Only N quits are required to be sent in the quantum channel to generate the raw key, then the straight k bits in the raw key are added bitwise to dilute the raw key, and a final key is consequently obtained to encrypt the database. By flexible adjusting of auxiliary parameters θ and k, privacy is secured and the query success ratio is improved. Feasibility and performance analyses indicate that the protocol has a high success ratio in first-trial query and is easy to implement, and that the communication complexity of O(N) is achieved. 相似文献
3.
4.
5.
现阶段的语义解析方法大部分都基于组合语义,这类方法的核心就是词典。词典是词汇的集合,词汇定义了自然语言句子中词语到知识库本体中谓词的映射。语义解析一直面临着词典中词汇覆盖度不够的问题。针对此问题,该文在现有工作的基础上,提出了基于桥连接的词典学习方法,该方法能够在训练中自动引入新的词汇并加以学习,为了进一步提高新学习到的词汇的准确度,该文设计了新的词语—二元谓词的特征模板,并使用基于投票机制的核心词典获取方法。该文在两个公开数据集(WebQuestions和Free917)上进行了对比实验,实验结果表明,该文方法能够学习到新的词汇,提高词汇的覆盖度,进而提升语义解析系统的性能,特别是召回率。 相似文献
6.
Mobile software applications have to cope with a particular environment that involves small size, limited resources, high autonomy requirements, competitive business models and many other challenges. To provide development guidelines that respond to these needs, several practices have been introduced; however, it is not clear how these guidelines may contribute to solve the issues present in the mobile domain. Furthermore, the rapid evolution of the mobile ecosystem challenges many of the premises upon which the proposed practices were designed. In this paper, we present a survey of the literature on software assurance practices for mobile applications, with the objective of describing them and assessing their contribution and success. We identified, organized and reviewed a body of research that spans in three levels: software development processes, software product assurance practices, and software implementation practices. By carrying out this literature survey, we reviewed the different approaches that researchers on Software Engineering have provided to address the needs that raise in the mobile software development arena. Moreover, we review the evolution of these practices, identifying how the constant changes and modernization of the mobile execution environment has impacted the methods proposed in the literature. Finally, we introduced discussion on the application of these practices in a real productive setting, opening an area for further research that may determine if practitioners have followed the proposed assurance paradigms. 相似文献
7.
This paper presents an integrated passive damping approach in hybrid metal-CFRP parts for structural applications. In this concept a viscoelastic material is embedded in the joint zone of the hybrid component. To examine the connection strength single-lap-joint specimens were produced and tested and the influence of the used material combinations, different surface structures, and different process parameters i.e. the moment of cross-linking were evaluated. Afterwards, the metal-CFRP hybrids were tested in quasi-static tests to assess their connection strength and failure behaviour. Dynamic cyclic tensile tests with step-wise increased loading conditions were performed to determine the specimens damping behaviour and to estimate their fatigue performance. Finally, these results are compared to a state of the art metal-CFRP hybrid with rivets connecting both materials. 相似文献
8.
In this paper, we consider the classical finite mixture model, which is an effective tool for modeling lifetime distributions for random samples from heterogeneous populations. We discuss new results on stochastic comparison for two finite mixtures when each of them is drawn from one of the following semiparametric families, i.e., proportional hazards, accelerated lifetime and proportional reversed hazards. 相似文献
9.
10.