全文获取类型
收费全文 | 9587篇 |
免费 | 1532篇 |
国内免费 | 1143篇 |
专业分类
电工技术 | 595篇 |
综合类 | 1545篇 |
化学工业 | 597篇 |
金属工艺 | 124篇 |
机械仪表 | 616篇 |
建筑科学 | 575篇 |
矿业工程 | 135篇 |
能源动力 | 131篇 |
轻工业 | 300篇 |
水利工程 | 286篇 |
石油天然气 | 254篇 |
武器工业 | 170篇 |
无线电 | 1520篇 |
一般工业技术 | 1477篇 |
冶金工业 | 305篇 |
原子能技术 | 81篇 |
自动化技术 | 3551篇 |
出版年
2024年 | 44篇 |
2023年 | 167篇 |
2022年 | 328篇 |
2021年 | 378篇 |
2020年 | 443篇 |
2019年 | 388篇 |
2018年 | 394篇 |
2017年 | 405篇 |
2016年 | 469篇 |
2015年 | 435篇 |
2014年 | 594篇 |
2013年 | 697篇 |
2012年 | 693篇 |
2011年 | 691篇 |
2010年 | 537篇 |
2009年 | 563篇 |
2008年 | 588篇 |
2007年 | 605篇 |
2006年 | 550篇 |
2005年 | 458篇 |
2004年 | 400篇 |
2003年 | 333篇 |
2002年 | 286篇 |
2001年 | 250篇 |
2000年 | 226篇 |
1999年 | 176篇 |
1998年 | 131篇 |
1997年 | 132篇 |
1996年 | 96篇 |
1995年 | 127篇 |
1994年 | 93篇 |
1993年 | 66篇 |
1992年 | 69篇 |
1991年 | 54篇 |
1990年 | 61篇 |
1989年 | 57篇 |
1988年 | 54篇 |
1987年 | 23篇 |
1986年 | 28篇 |
1985年 | 18篇 |
1984年 | 12篇 |
1983年 | 11篇 |
1982年 | 16篇 |
1981年 | 10篇 |
1980年 | 7篇 |
1977年 | 10篇 |
1965年 | 7篇 |
1964年 | 8篇 |
1961年 | 12篇 |
1959年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
31.
32.
Scale selection using three different representations for images 总被引:1,自引:0,他引:1
J. Martinez-Baena J. A. García J. Fdez-Valdivia Rosa Rodriguez-Sanchez 《Pattern recognition letters》1997,18(14):1453-1467
33.
利用随机振动复模态分析,提出了一种求解时变线性系统,在确定性激励与随机激励共同作用下非平稳随机响应的计算方法,并以舰载火箭武器系统为研究对象,用该法探讨了海浪对舰面火箭发射初始扰动和系统振动特性的影响。 相似文献
34.
设{Z,(W)}是定义在概率空间上的独立的随机变量序列,Z(W)具有方差为期望E(Zn)=0.本文证明了对任意算数序列{bn}及任意的存在充分大的整数N>0使当N'>N″>N时.有此不等式在随机级数研究中有重要作用. 相似文献
35.
36.
介绍了为光敏丝室探测器PET而设计的触发判选处理器(TRIG)的结构和原理,该处理器具有触发判选,计数率损失测量,随机符合事例率测量,探测器分区计数统计以及系统定标等多项功能,由于应用了EPLD技术和流水线作业等技术,实现了TRIG系统的高集成度和高性能 。 相似文献
37.
There is a need for developing low cost, easily and abundantly available, yet efficient, adsorbents for the removal of phosphates during the tertiary treatment of wastewaters. The tamarind nut shell activated carbon (TNSAC) prepared on a laboratory scale has been used to evaluate its performance for phosphate adsorption. This paper describes the laboratory production of this adsorbent material in its various forms, and discusses the effects of the TNSAC process variables (the unrinsed and rinsed forms of the TNSAC and the impregnation ratio) on its performance in adsorbing phosphate. The material has been shown to be a good alternative adsorbent. As much as 95% phosphate removal by the unrinsed TNSAC is possible in about 30 min under the test conditions. The phosphate adsorbing capacity is about two times higher for the unrinsed TNSAC in comparison to the rinsed TNSAC. The adsorption rates, however, transit to extremely low rates towards the end when equilibrium conditions could be attained in about 2 h contact time. The phosphate removal mechanics are adsorption and precipitation/ion exchange when unrinsed TNSAC is used, and adsorption alone for the rinsed TNSAC. The maximum phosphate removal is found to take place at an impregnation ratio of 1.0 for both forms of the TNSAC. 相似文献
38.
A semi-analytic boundary element method for parabolic problems 总被引:1,自引:0,他引:1
A new semi-analytic solution method is proposed for solving linear parabolic problems using the boundary element method. This method constructs a solution as an eigenfunction expansion using separation of variables. The eigenfunctions are determined using the dual reciprocity boundary element method. This separation of variables-dual reciprocity method (SOV-DRM) allows a solution to be determined without requiring either time-stepping or domain discretisation. The accuracy and computational efficiency of the SOV-DRM is found to improve as time increases. These properties make the SOV-DRM an attractive technique for solving parabolic problems. 相似文献
39.
Giorgio Vittadini Marco Fattore Pietro G. Lovaglio 《Computational statistics & data analysis》2007,51(12):5828-5846
A new approach for the estimation and the validation of a structural equation model with a formative-reflective scheme is presented. The basis of the paper is a proposal for overcoming a potential deficiency of PLS path modeling. In the PLS approach the reflective scheme assumed for the endogenous latent variables (LVs) is inverted; moreover, the model errors are not explicitly taken into account for the estimation of the endogenous LVs. The proposed approach utilizes all the relevant information in the formative manifest variables (MVs) providing solutions which respect the causal structure of the model. The estimation procedure is based on the optimization of the redundancy criterion. The new approach, entitled redundancy analysis approach to path modeling (RA-PM) is compared with both traditional PLS Path Modeling and LISREL methodology, on the basis of real and simulated data. 相似文献
40.
Identification of Chaos Representations of Elastic Properties of Random Media Using Experimental Vibration Tests 总被引:1,自引:1,他引:0
This paper deals with the experimental identification of the probabilistic representation of a random field modelling the
Young modulus of a nonhomogeneous isotropic elastic medium by experimental vibration tests. Experimental data are constituted
of frequency response functions on a given frequency band and for a set of observed degrees of freedom on the boundary of
specimens. The random field representation is based on the polynomial chaos decomposition. The coefficients of the polynomial
chaos are identified setting an inverse problem and then in solving an optimization problem related to the maximum likelihood
principle. 相似文献