全文获取类型
收费全文 | 107468篇 |
免费 | 3913篇 |
国内免费 | 2730篇 |
专业分类
电工技术 | 3124篇 |
综合类 | 4948篇 |
化学工业 | 14172篇 |
金属工艺 | 6255篇 |
机械仪表 | 4960篇 |
建筑科学 | 3987篇 |
矿业工程 | 1528篇 |
能源动力 | 1730篇 |
轻工业 | 6143篇 |
水利工程 | 2120篇 |
石油天然气 | 1094篇 |
武器工业 | 393篇 |
无线电 | 11878篇 |
一般工业技术 | 18137篇 |
冶金工业 | 3360篇 |
原子能技术 | 722篇 |
自动化技术 | 29560篇 |
出版年
2024年 | 147篇 |
2023年 | 393篇 |
2022年 | 957篇 |
2021年 | 1243篇 |
2020年 | 835篇 |
2019年 | 584篇 |
2018年 | 15073篇 |
2017年 | 14085篇 |
2016年 | 10579篇 |
2015年 | 1592篇 |
2014年 | 1540篇 |
2013年 | 1749篇 |
2012年 | 5145篇 |
2011年 | 11410篇 |
2010年 | 10231篇 |
2009年 | 7485篇 |
2008年 | 8763篇 |
2007年 | 9883篇 |
2006年 | 1905篇 |
2005年 | 2612篇 |
2004年 | 2260篇 |
2003年 | 1841篇 |
2002年 | 1176篇 |
2001年 | 692篇 |
2000年 | 641篇 |
1999年 | 224篇 |
1998年 | 93篇 |
1997年 | 73篇 |
1996年 | 72篇 |
1995年 | 22篇 |
1994年 | 23篇 |
1993年 | 22篇 |
1992年 | 28篇 |
1991年 | 38篇 |
1988年 | 19篇 |
1969年 | 24篇 |
1968年 | 43篇 |
1967年 | 33篇 |
1966年 | 43篇 |
1965年 | 44篇 |
1963年 | 28篇 |
1962年 | 22篇 |
1961年 | 18篇 |
1960年 | 30篇 |
1959年 | 42篇 |
1958年 | 37篇 |
1957年 | 37篇 |
1956年 | 34篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
2.
3.
VASP(Vienna Ab-initio Simulation Package)是基于密度泛函理论的通用材料计算模拟软件。随着高性能计算平台的广泛使用和高通量计算的兴起,VASP计算任务的复杂性和数据量也大幅度提升。为了提高材料理论计算的方便程度,减少大量重复的指令和结果检查的复杂性,本文提供了一个基于Python语言的VASP计算辅助程序VaspCZ,能够大幅提高研究者的科研效率。该程序包含软件部分和API部分,软件部分提供了命令行用户界面,基于基本的Linux命令即可一键完成VASP计算的相关操作,为无编程语言基础的研究人员提供了便利。应用程序接口部分服务于具有Python语言基础的研究者,提供了底层库,使得自定义计算(如高通量计算、编写高级应用等)更为简单快捷。本程序包可以显著提高VASP的计算效率,并已经通过Github开源项目公开,提供了详细的使用文档、使用示例和API接口,有望能为广大材料理论研究者提供便利。 相似文献
4.
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
5.
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
6.
ULK1 (unc-51 like autophagy activating kinase 1), a mammalian serine/threonine kinase, is a key component of
autophagy initiation complex and helps to induce all types of autophagy. Canonical autophagy is a process in which,
through the interactions of a series of autophagy-related proteins, damaged organelles or misfolded proteins are
engulfed by autophagosomes and then merged with lysosomes to be degraded. Thus, canonical autophagy is an
important constituent part of the cellular “quality control.” Besides, accumulating evidence indicates that ULK1 exerts
autophagy-independent effects in a cell-specific manner. For example, ULK1 facilitates neurite elongation through the
regulation of endoplasmic reticulum (ER)–Golgi trafficking in neurons, stimulates phosphopentose pathway to help
NADPH (nicotinamide adenine dinucleotide phosphate hydrogen) production, and acts as a duplex regulator in type
I IFN (type I interferon) induced innate immune response. Considering the importance and diversity of ULK1 in
various biological processes, this review aims to present a comprehensive overview of autophagy and non-autophagy
related functions of ULK1 in a variety of human physiological, pathological, and disease processes. 相似文献
7.
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
8.
9.
10.
Variations of Incomplete Open Cubes is the major project by the twentieth-century conceptual artist Sol LeWitt. In this paper we interpret the enumerative component of the project as embeddings of graphs. This formulation permits use of an algorithm to check the completeness of the list of the structures produced by the artist. Our conclusion is that the artist found the correct number of structures (that is, 122), but that his list contains a mistake in the presentation of a pair of incomplete cubes, a discovery that appears not to have been noted before. 相似文献