全文获取类型
收费全文 | 23011篇 |
免费 | 2815篇 |
国内免费 | 2319篇 |
专业分类
电工技术 | 2462篇 |
综合类 | 3281篇 |
化学工业 | 1650篇 |
金属工艺 | 1196篇 |
机械仪表 | 1455篇 |
建筑科学 | 1068篇 |
矿业工程 | 363篇 |
能源动力 | 441篇 |
轻工业 | 749篇 |
水利工程 | 451篇 |
石油天然气 | 517篇 |
武器工业 | 269篇 |
无线电 | 3344篇 |
一般工业技术 | 2725篇 |
冶金工业 | 465篇 |
原子能技术 | 265篇 |
自动化技术 | 7444篇 |
出版年
2024年 | 96篇 |
2023年 | 370篇 |
2022年 | 509篇 |
2021年 | 593篇 |
2020年 | 740篇 |
2019年 | 701篇 |
2018年 | 655篇 |
2017年 | 925篇 |
2016年 | 966篇 |
2015年 | 927篇 |
2014年 | 1389篇 |
2013年 | 1834篇 |
2012年 | 1662篇 |
2011年 | 1777篇 |
2010年 | 1388篇 |
2009年 | 1461篇 |
2008年 | 1340篇 |
2007年 | 1509篇 |
2006年 | 1261篇 |
2005年 | 1153篇 |
2004年 | 976篇 |
2003年 | 847篇 |
2002年 | 744篇 |
2001年 | 643篇 |
2000年 | 593篇 |
1999年 | 485篇 |
1998年 | 370篇 |
1997年 | 370篇 |
1996年 | 284篇 |
1995年 | 231篇 |
1994年 | 224篇 |
1993年 | 174篇 |
1992年 | 154篇 |
1991年 | 144篇 |
1990年 | 138篇 |
1989年 | 105篇 |
1988年 | 64篇 |
1987年 | 48篇 |
1986年 | 30篇 |
1985年 | 28篇 |
1984年 | 39篇 |
1983年 | 41篇 |
1982年 | 34篇 |
1981年 | 29篇 |
1980年 | 21篇 |
1979年 | 12篇 |
1978年 | 11篇 |
1977年 | 14篇 |
1976年 | 6篇 |
1975年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
121.
谈国新 《华中科技大学学报(城市科学版)》1994,(2)
本文提出了一种基于自然数线性八叉树的优化构造算法。该算法以活动结点表为中间辅助结构,在图像输入过程中直接生成基于N码的八叉树叶结点.与常规构造算法相比,新提出的优化构造算法省去了N码的计算及合并过程,从而具有较高的时空效率. 相似文献
122.
线性规划模型的自动生成与求解 总被引:1,自引:0,他引:1
本文描述了《有色企业经济活动分析决策支持系统》模型库中线性规划模型的自动生成与求解系统的设计思想、方法及实现 相似文献
123.
采用同调约束快速识别的有功校正控制计算 总被引:1,自引:0,他引:1
本文发展了文(5)提出的同调约束概念,将同调约束进一步分为正同调约束和反同调约束两组。文中提出了一种新的同调约束识别方法,不必增加任何计算便可快速识别出正反同调约束,显著地降低了解题规模。IEEE30节点样本网络的计算实例证实了本文方法的有效性。 相似文献
124.
125.
具有多值约束的线性递归查询的有效计算 总被引:1,自引:0,他引:1
本文给出三个算法,分别用于把给定的右线性、左线性或左-右线性递归程序改写为一组更有效的规则.与Ullman等人的变换算法不同,本文的算法允许查询的初始约束可以是含任意多个约束元组的集合,而不必是单值的;这样,本文的算法不仅可以用于查询的求值,而且也可以用于子目标的处理.变换算法的正确性和变换后规则的有效性也在本文简略讨论. 相似文献
126.
Junya Kondoh Yoichi Tomii Katsuhiro Kawachi 《Journal of the American Ceramic Society》2003,86(12):2093-2102
Methods of suppressing decreased conductivity in 8 mol% Y2 O3 -stabilized–92 mol% ZrO2 (8YSZ) with aging were investigated. Different amounts of Sc2 O3 were doped into 8YSZ. The electrochemical properties of Sc2 O3 -doped 8YSZ were measured, and the microstructural and local structural changes were characterized. The present results indicate that an appropriate amount of Sc2 O3 doping, 3 or 4 mol%, effectively suppresses decreased conductivity with aging in 8YSZ. 相似文献
127.
A new curvature technique calculation for surface tension contribution in PLIC-VOF method 总被引:1,自引:0,他引:1
The volume of fluid (VOF) methods have been used for numerous numerical simulations. Among these techniques used to define
the moving interface, the piecewise linear interface reconstruction (PLIC-VOF) is one of the most accurate. A study of the
superficial tension impact on two-phase flow with free surface is presented. A new method based on direct staggered grid is
developped to include surface tension in PLIC-VOF. The new numerical curvature calculation method doesn't need smoothed colour
function and leads to less “spurious current”. This technique is applied to the calculus of surface tension force in the case
of the rise of air bubble in viscous liquid and the fall of liquid drop in the same liquid on free surface. Droplets, thin
layer and capillarity waves are observed after the free surface rupture for different Bond number. The influence of surface
tension calculus is then obvioused and when the drop hit the free surface, wavelets propagate toward the virtual boundaries
imposed. 相似文献
128.
William E Acree Jr Michael H Abraham 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(8):1441-1446
The contentions made in an earlier paper [J Chem Technol Biotechnol 80 : 133–137 (2005)] that the coefficients of the Abraham solvation equation do not provide meaningful information on the molecular properties of ionic liquid solvents is refuted. The objections noted in the earlier paper disappear when the solvation equation model is correctly applied to the experimental data. It is further shown that the coefficients of the Abraham solvation equations can be used to characterize ionic liquids and can be used to select solvents for the solubility of gaseous solutes. Copyright © 2006 Society of Chemical Industry 相似文献
129.
N. I. Bobyr’ A. P. Grabovskii A. V. Timoshenko A. P. Khalimon 《Strength of Materials》2006,38(1):92-98
Within framework of the continual fracture mechanics, we describe the engineering approach to the assessment of scattered
microdamage accumulation kinetics in metallic materials under elastoplastic loading conditions in case of plane stressed state.
Automatized experimental stand and the respective investigation technique are discussed. The stand has been developed based
on modification of the UMé-10T electromechanic test machine. State-of-the-art computer technologies and microprocessing hardware
are incorporated in the stand automation. We present the technique of experimental assessment of damage accumulation kinetics
in metallic structural materials under complex elastoplastic loading conditions with account of two different fracture (cleavage
and shear) processes, which technique is based on measuring the specific electric resistance of the specimen.
__________
Translated from Problemy Prochnosti, No. 1, pp. 128–137, January–February, 2006. 相似文献
130.
High accuracy path tracking for vehicles in presence of sliding: Application to farm vehicle automatic guidance for agricultural tasks 总被引:1,自引:0,他引:1
Roland Lenain Benoit Thuilot Christophe Cariou Philippe Martinet 《Autonomous Robots》2006,21(1):79-97
When designing an accurate automated guidance system for vehicles, a major problem is sliding and pseudo-sliding effects. This is especially the case in agricultural applications, where five-centimetre accuracy with respect to the desired trajectory is required, although the vehicles are moving on slippery ground. It has been established that RTK GPS was a very suitable sensor to achieve automated guidance with such high precision: several control laws have been designed for vehicles equipped with this sensor, and provide the expected guidance accuracy as long as the vehicles do not slide. In previous work, further control developments have been proposed to take sliding into account: guidance accuracy in slippery environments has been shown to be preserved, except transiently at the beginning/end of curves. In this paper, the design of this control law is first recalled and discussed. A Model Predictive Control method is then applied in order to preserve accuracy of guidance even during these curvature transitions. Finally, the overall control scheme is implemented, and improvements with respect to previous guidance laws are demonstrated through full-scale experiments. 相似文献