全文获取类型
收费全文 | 239003篇 |
免费 | 22408篇 |
国内免费 | 10561篇 |
专业分类
电工技术 | 14550篇 |
技术理论 | 30篇 |
综合类 | 23770篇 |
化学工业 | 34358篇 |
金属工艺 | 10419篇 |
机械仪表 | 12116篇 |
建筑科学 | 32162篇 |
矿业工程 | 13598篇 |
能源动力 | 8781篇 |
轻工业 | 18826篇 |
水利工程 | 11275篇 |
石油天然气 | 13347篇 |
武器工业 | 3291篇 |
无线电 | 14916篇 |
一般工业技术 | 18021篇 |
冶金工业 | 13121篇 |
原子能技术 | 1983篇 |
自动化技术 | 27408篇 |
出版年
2024年 | 1114篇 |
2023年 | 3251篇 |
2022年 | 6210篇 |
2021年 | 8032篇 |
2020年 | 7976篇 |
2019年 | 6066篇 |
2018年 | 5718篇 |
2017年 | 7060篇 |
2016年 | 8555篇 |
2015年 | 9131篇 |
2014年 | 16198篇 |
2013年 | 14525篇 |
2012年 | 17295篇 |
2011年 | 18908篇 |
2010年 | 13899篇 |
2009年 | 14169篇 |
2008年 | 12853篇 |
2007年 | 15706篇 |
2006年 | 14245篇 |
2005年 | 12393篇 |
2004年 | 10372篇 |
2003年 | 8991篇 |
2002年 | 7353篇 |
2001年 | 6092篇 |
2000年 | 5180篇 |
1999年 | 4142篇 |
1998年 | 2953篇 |
1997年 | 2584篇 |
1996年 | 2135篇 |
1995年 | 1787篇 |
1994年 | 1485篇 |
1993年 | 1082篇 |
1992年 | 884篇 |
1991年 | 651篇 |
1990年 | 561篇 |
1989年 | 515篇 |
1988年 | 304篇 |
1987年 | 255篇 |
1986年 | 217篇 |
1985年 | 249篇 |
1984年 | 195篇 |
1983年 | 142篇 |
1982年 | 87篇 |
1981年 | 86篇 |
1980年 | 91篇 |
1979年 | 40篇 |
1978年 | 25篇 |
1977年 | 24篇 |
1975年 | 18篇 |
1959年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
951.
The paper reports the experimental investigation data for the effect that nonparallel faces of bars under impact exert on
the parameters of longitudinal and bending strain waves generated in the bars. The changes in stress magnitudes in the bar
under impact with growing angle of the impact faces offset are described.
__________
Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 6, pp. 73–78, November–December, 2006. 相似文献
952.
953.
V. M. García A. Vidal V. E. Boria A. M. Vidal 《International journal for numerical methods in engineering》2006,65(11):1773-1788
In this paper, a special purpose algorithm for solving large eigenvalue problems based on the Lanczos method is successfully applied to an engineering problem: the electromagnetic analysis and design of passive waveguide devices. For dealing with such complex problems, the boundary integral‐resonant mode expansion (BI‐RME) technique has been recently proposed. This technique solves integral equations (IEs) through the well‐known method of moments (MoM), thus leading to structured eigenvalue problems. These problems frequently become very large when solving complex arbitrary geometries with high accuracy. In such cases, the eigenvalue problem cannot be efficiently solved with standard methods by means of personal computers, essentially due to CPU time and memory allocation requirements. In this paper, we propose an alternative technique, based on the Lanczos method, for the fast and accurate solution of large BI‐RME generalized eigenvalue problems. The novel theoretical aspects of this approach, as well as the impacton the original BI‐RME formulation, are described. Comparative benchmarks are also successfully presented for the full‐wave analysis and design of real passive microwave devices. Copyright © 2005 John Wiley Sons, Ltd. 相似文献
954.
Safe and Economic Operation of Power Plants – Research Results in the Field of Materials, Design and Maintenance Components of power plants which undergo high temperatures are subjected to complex loading situations. The requirements on the used materials result from the special operation conditions of the plants and have to be adjusted to the steadily growing requirements on higher efficiency of the complete power plant as well as to those of safe and economic operation. The expenses for control and downtimes are directly connected with economic efficiency and availability. However, in case of new procedures or components it is not possible to revert to the existing know‐how. Different failure mechanisms than known before can occur. The same goes for the load situation. Therefore the knowledge base has to be extended to in‐advance or even parallely running scientific examinations that life assessment and maintenance strategies can be applied which guarantee the operational reliability and the efficiency of the plant. The main emphasis of these F&E works has to be put on condition monitoring based on actual operational data, the standard materials’ and component’s behaviour (deformation, damage and failure behaviour) in connection with design of components and the related material laws. In the framework of applied AVIF projects, following problems are handled:. – qualification of materials by determinating parameters related to practise. – optimal design of components by making available material laws and numerical tools. – economic manufacturing of components by qualifying processing methods such as welding. – The results can be transferred to concepts for safe and economic operation of power plants, especially for newly introduced materials for which there is no operational experience available. 相似文献
955.
956.
MEMORY·童年·印象--合肥市政务文化新区儿童公园概念性方案 总被引:1,自引:0,他引:1
合肥市政务文化新区儿童乐园的概念性方案,充分考虑了儿童的心理和成长交流需要,以儿童的自发活动为特色,兼顾各类活动设施,创造丰富活动空间,构筑了一个富有感染力、空间变幻多彩的都市儿童乐园. 相似文献
957.
低效油气井生产的劳动组织管理方式与正规油气开发有所不同。文章对低效油气井定员编制进行了初步探讨,比较了两种轮班作业制度,并提出了加强低效油气生产劳动管理的建议。 相似文献
958.
In the pulp and paper industry, during major modernization projects the overall energy system consequences are often not estimated in detail, usually only local energy consequences are taken into account when evaluating possible projects. In this paper, the effects on the overall energy system when installing an advanced delignification process (i.e., a “state‐of‐the‐art” pulp digester and oxygen delignification process) will be presented. Also, the effect such an installation has on the potential for further energy integration is discussed. Furthermore, the CO2 consequences for both installing such a system and integrating the mill further energy‐wise are presented. 相似文献
959.
介绍了消失模铸造工艺对成型机的特殊要求,高性能成型机在大规模工业化消失模生产中的重要性,重点阐述了德国Teubert公司TVY130/90消失模成型机的特点及应用,并对成型机的国产化研究与开发提出了建议。 相似文献
960.
略论闽台文化的渊源及其特有的伦理价值观 总被引:2,自引:0,他引:2
刘清 《重庆理工大学学报(自然科学版)》2006,20(7):108-110
闽台文化是中华文化的一个组成部分。其根源是中原之河洛文化。特殊的地理位置、特殊的生活环境使闽台文化中的伦理价值颇具特色。闽台文化对中华文化的传承与补充反映了海峡两岸的亲密关系。 相似文献