全文获取类型
收费全文 | 27078篇 |
免费 | 4256篇 |
国内免费 | 2865篇 |
专业分类
电工技术 | 1278篇 |
技术理论 | 1篇 |
综合类 | 2073篇 |
化学工业 | 2217篇 |
金属工艺 | 846篇 |
机械仪表 | 1174篇 |
建筑科学 | 4316篇 |
矿业工程 | 2020篇 |
能源动力 | 703篇 |
轻工业 | 757篇 |
水利工程 | 868篇 |
石油天然气 | 1895篇 |
武器工业 | 112篇 |
无线电 | 1815篇 |
一般工业技术 | 2356篇 |
冶金工业 | 2617篇 |
原子能技术 | 135篇 |
自动化技术 | 9016篇 |
出版年
2024年 | 520篇 |
2023年 | 1393篇 |
2022年 | 2349篇 |
2021年 | 2203篇 |
2020年 | 1919篇 |
2019年 | 1345篇 |
2018年 | 900篇 |
2017年 | 882篇 |
2016年 | 824篇 |
2015年 | 897篇 |
2014年 | 1440篇 |
2013年 | 1521篇 |
2012年 | 1446篇 |
2011年 | 1748篇 |
2010年 | 1374篇 |
2009年 | 1442篇 |
2008年 | 1286篇 |
2007年 | 1471篇 |
2006年 | 1376篇 |
2005年 | 1241篇 |
2004年 | 933篇 |
2003年 | 858篇 |
2002年 | 726篇 |
2001年 | 570篇 |
2000年 | 529篇 |
1999年 | 477篇 |
1998年 | 508篇 |
1997年 | 313篇 |
1996年 | 264篇 |
1995年 | 183篇 |
1994年 | 183篇 |
1993年 | 141篇 |
1992年 | 134篇 |
1991年 | 122篇 |
1990年 | 118篇 |
1989年 | 68篇 |
1988年 | 64篇 |
1987年 | 49篇 |
1986年 | 69篇 |
1985年 | 78篇 |
1984年 | 51篇 |
1983年 | 47篇 |
1982年 | 31篇 |
1981年 | 17篇 |
1980年 | 23篇 |
1979年 | 17篇 |
1978年 | 12篇 |
1977年 | 8篇 |
1975年 | 5篇 |
1959年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
深基坑支护结构计算的有限元方法 总被引:3,自引:0,他引:3
针对软土地基的特性,本文提出了考虑土体抗力释放与结构模型随施工过程改变的新杆系有限元法,并 编制了求解支护结构内力与变形的计算程序,通过对事例分析.计算结果与实际情况非常吻合,证明了该方法的合理 性。 相似文献
12.
13.
PLC 控制电梯教学模型的设计与调试 总被引:1,自引:0,他引:1
主要介绍了8层集选电梯的PLC控制系统的总体设计方案、组成,PLC的控制方案及模块化程序设计、在实际的安装与调试中遇到的问题,以及制作该教学模型的现实意义。 相似文献
14.
15.
16.
Javier Roca-Pardiñas Carmen Cadarso-Suárez María J. Lado 《Computational statistics & data analysis》2008,52(4):1958-1970
In many applications, the joint effect of two continuous covariates on the target binary response may vary across groups defined by levels of a given factor. A testing procedure that would enable this type of surface-by-factor interactions to be detected has been designed. To accomplish this goal, a logistic generalized additive model (GAM) with bivariate continuous interactions varying across groups defined by levels of a factor is considered. A local scoring algorithm based on local linear kernel smoothers was implemented to estimate the proposed logistic GAM. Bootstrap resampling techniques were used for the purpose of testing for factor-by-surface interactions. Given the high computational cost involved, binning techniques were used to speed up computation in the estimation and testing processes. The adequacy of the bootstrap-based test was assessed by means of a simulation study. If a factor-by-surface interaction is detected in the model, it is then established that the use of the odds-ratio curves is very useful in obtaining a direct interpretation of the fitted model. The benefits of using this methodology when analyzing real data are illustrated by applying the technique to the outputs produced by a computerized system dedicated to the early detection of breast cancer. 相似文献
17.
18.
19.
Awareness of the construction environment can be improved by automatic three-dimensional (3D) sensing and modeling of job sites in real time. Commercially available 3D modeling approaches based on range scanning techniques are capable of modeling static objects only, and thus cannot model dynamic objects in real time in an environment comprised of moving humans, equipment, and materials. Emerging prototype video range cameras offer an alternative by facilitating affordable, wide field of view, dynamic object tracking at frame rates better than 1?Hz (real time). This paper describes a methodology to model, detect, and track the position of static and moving objects in real time, based on data obtained from video range cameras. Experiments with this technology have produced results that indicate that video rate 3D data acquisition and analysis of construction environments can support effective modeling, detection, and tracking of project resources. This approach to job site awareness has inherent value and broad application. In combination with effective management practices and other sensing techniques, this technology has the potential to significantly improve safety on construction job sites. 相似文献
20.
This paper presents an analysis of the data collected in the ambient vibration test of the International Guadiana cable-stayed Bridge, which links Portugal and Spain, based on different output-only identification techniques: peak-picking, frequency domain decomposition, covariance-driven stochastic subspace identification, and data-driven stochastic subspace identification. The purpose of the analysis is to compare the performance of the four techniques and evaluate their efficiency in dealing with specific challenges involved in the modal identification of the tested cable-stayed bridge, namely the existence of closely spaced modes, the perturbation produced by the local vibration of stay-cables, and the variation of modal damping coefficients with wind velocity. The identified natural frequencies and mode shapes are compared with the corresponding modal parameters provided by a previously developed numerical model. Additionally, the variability of some modal damping coefficients is related with the variation of the wind characteristics and associated with a component of aerodynamic damping. 相似文献