全文获取类型
收费全文 | 13184篇 |
免费 | 976篇 |
国内免费 | 586篇 |
专业分类
电工技术 | 1983篇 |
技术理论 | 1篇 |
综合类 | 1320篇 |
化学工业 | 552篇 |
金属工艺 | 635篇 |
机械仪表 | 2037篇 |
建筑科学 | 753篇 |
矿业工程 | 677篇 |
能源动力 | 398篇 |
轻工业 | 334篇 |
水利工程 | 275篇 |
石油天然气 | 1210篇 |
武器工业 | 155篇 |
无线电 | 1082篇 |
一般工业技术 | 510篇 |
冶金工业 | 1192篇 |
原子能技术 | 191篇 |
自动化技术 | 1441篇 |
出版年
2024年 | 32篇 |
2023年 | 108篇 |
2022年 | 245篇 |
2021年 | 295篇 |
2020年 | 352篇 |
2019年 | 233篇 |
2018年 | 215篇 |
2017年 | 292篇 |
2016年 | 361篇 |
2015年 | 408篇 |
2014年 | 790篇 |
2013年 | 646篇 |
2012年 | 969篇 |
2011年 | 1079篇 |
2010年 | 779篇 |
2009年 | 723篇 |
2008年 | 662篇 |
2007年 | 950篇 |
2006年 | 903篇 |
2005年 | 777篇 |
2004年 | 655篇 |
2003年 | 608篇 |
2002年 | 470篇 |
2001年 | 433篇 |
2000年 | 348篇 |
1999年 | 284篇 |
1998年 | 250篇 |
1997年 | 184篇 |
1996年 | 152篇 |
1995年 | 121篇 |
1994年 | 95篇 |
1993年 | 50篇 |
1992年 | 45篇 |
1991年 | 38篇 |
1990年 | 31篇 |
1989年 | 33篇 |
1988年 | 13篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1984年 | 5篇 |
1965年 | 7篇 |
1964年 | 7篇 |
1962年 | 5篇 |
1961年 | 8篇 |
1960年 | 5篇 |
1959年 | 13篇 |
1958年 | 8篇 |
1957年 | 6篇 |
1956年 | 5篇 |
1955年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
11.
运用过程中各类相关因子的变化,会使得机车柴油机配气相位出现一定程度变化,采取某种措施调整或是处理可以解决动力不足的问题。 相似文献
12.
In the early design stage, automotive modeling should both meet the requirements of aesthetics and engineering. Therefore, a vehicle CAD (computer aided design) model that can be easily adjusted by feedbacks is necessary. Based on CE-Bézier surface, this paper presents a set of algorithms for parametric segmentation and fairing surface generation in a car model. This model is defined by a simplified automotive template and relevant control points, shape parameters and segmentation parameters, which can be modified to alter the car form efficiently. With this model and the corresponding adjustment method, more than fifty various vehicle models are established in this research according to different parameters. And two methods for calculating similarity index between car models are constructed, which are suitable for brand design trend analysis and modelling design decisionmaking. 相似文献
13.
The polymer electrolyte based solid-state lithium metal batteries are the promising candidate for the high-energy electrochemical energy storage with high safety and stability. Moreover, the intrinsic properties of polymer electrolytes and interface contact between electrolyte and electrodes have played critical roles for determining the comprehensive performances of solid-state lithium metal batteries. In this review, the development of polymer electrolytes with the design strategies by functional units adjustments are firstly discussed. Then the interfaces between polymer electrolyte and cathode/anode, including the interface issues, remedy strategies for stabilizing the interface contact and reducing resistances, and the in-situ polymerization method for enhancing the compatibilities and assembling the batteries with favorable performances, have been introduced. Lastly, the perspectives on developing polymer electrolytes by functional units adjustment, and improving interface contact and stability by effective strategies for solid-state lithium metal batteries have been provided. 相似文献
14.
15.
16.
Silverberg Koerner Susan; Wallace Sara; Jacobs Lehman Stephanie; Lee Sun-A; Escalante Kristine A. 《Canadian Metallurgical Quarterly》2004,18(1):46
This study addressed two main questions: (a) Are adolescent sons and daughters exposed to sensitive maternal disclosures after divorce with similar frequency and in similar detail? and (b) Does gender act as a moderator in the association between maternal disclosures and adolescent adjustment difficulties? Forced-choice and open-ended data were collected from 194 adolescents within 2 years after their parents' divorce. Quantitative analyses revealed that although the majority of adolescents experience some level of maternal disclosure, neither frequency nor detail of maternal disclosure differed as a function of adolescent gender. Frequent and detailed maternal disclosures were associated with adolescent adjustment difficulties, primarily psychological distress. Gender did not moderate that significant association. Qualitative analysis shed light on the link between maternal disclosures and adolescent distress, suggested the importance of how disclosures are made, and revealed several gender differences in reactions to maternal disclosures. Implications of the findings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
17.
测向定位技术是无线电管理的一个重要课题。测向定位过程中的误差的种类和产生的原因很多。选择适当的方法对误差进行校正,可以有效的减小测向误差带来的损失,提高无线电管理的效率。 相似文献
18.
19.
20.