全文获取类型
收费全文 | 53536篇 |
免费 | 3789篇 |
国内免费 | 2322篇 |
专业分类
电工技术 | 2771篇 |
技术理论 | 2篇 |
综合类 | 6655篇 |
化学工业 | 2837篇 |
金属工艺 | 1425篇 |
机械仪表 | 1931篇 |
建筑科学 | 23171篇 |
矿业工程 | 3332篇 |
能源动力 | 996篇 |
轻工业 | 1465篇 |
水利工程 | 3429篇 |
石油天然气 | 1691篇 |
武器工业 | 261篇 |
无线电 | 1655篇 |
一般工业技术 | 2953篇 |
冶金工业 | 1660篇 |
原子能技术 | 205篇 |
自动化技术 | 3208篇 |
出版年
2024年 | 128篇 |
2023年 | 383篇 |
2022年 | 816篇 |
2021年 | 1006篇 |
2020年 | 972篇 |
2019年 | 814篇 |
2018年 | 834篇 |
2017年 | 1040篇 |
2016年 | 1266篇 |
2015年 | 1516篇 |
2014年 | 4060篇 |
2013年 | 2397篇 |
2012年 | 4027篇 |
2011年 | 4307篇 |
2010年 | 3764篇 |
2009年 | 4069篇 |
2008年 | 3435篇 |
2007年 | 4226篇 |
2006年 | 3699篇 |
2005年 | 3112篇 |
2004年 | 2503篇 |
2003年 | 2136篇 |
2002年 | 1790篇 |
2001年 | 1476篇 |
2000年 | 1206篇 |
1999年 | 991篇 |
1998年 | 723篇 |
1997年 | 637篇 |
1996年 | 515篇 |
1995年 | 473篇 |
1994年 | 323篇 |
1993年 | 219篇 |
1992年 | 191篇 |
1991年 | 130篇 |
1990年 | 101篇 |
1989年 | 84篇 |
1988年 | 56篇 |
1987年 | 64篇 |
1986年 | 24篇 |
1985年 | 15篇 |
1984年 | 20篇 |
1983年 | 17篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 18篇 |
1979年 | 21篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 656 毫秒
991.
CPU桥ASIC设计中CPU模拟器的设计 总被引:1,自引:1,他引:0
功能模拟是设计高性能微处理器接口ASIC芯片的重要环节,目的是消除ASIC的功能性设计错误。为了更好地对ASIC芯片进行模拟,需要灵活、方便、能够体现微处理器行为的CPU模型,文章将介绍了对一个CPU行为模拟器的开发。 相似文献
992.
Daizhan Cheng 《Asian journal of control》2000,2(2):132-139
This paper tackles the problem of stabilization of a class of non‐minimum phase nonlinear systems which have zero dynamics with an eigenvalue zero of multiplicity 2. By adding some new terms, called cross terms, we are able to generalize the concept of the Lyapunov function with a homogeneous derivative along the trajectory, which was introduced in [4], to produce a suitable Lyapunov function. The Lyapunov function assures that the stability of an approximate system, which consists of some lower order terms of a nonlinear system with an eigenvalue zero of multiplicity 2, implies the stability of the whole system. Applying these to non‐minimum phase zero dynamics of nonlinear systems with such a center, a sufficient condition and a design method of state feedback control are obtained for stabilizing the systems. 相似文献
993.
N.V. Banichuk F. Ragnedda M. Serra 《Structural and Multidisciplinary Optimization》2000,19(4):303-310
The problem of optimal structural design of shallow thin-walled elements such as curved rectangular plates are formulated
and solved for dynamic conditions. The distribution of the initial curvature of shallow plates in a nonstrained state is taken
as the control function. Dynamic compliance is considered as the minimized performance functional. Optimality conditions are
derived for the distributed parameter system considered and applied for the construction of the analytical solution. The rigorous
analysis of extremum conditions and behavioural equations shows that the initial optimization problem is decomposed into several
problems of classical structural analysis, which can be successfully solved analytically. Some optimal designs obtained for
rectangular plates under stretching and bending, and a plate lying on an elastic foundation and subjected to lateral forces
are presented.
Received: November 27, 1998 相似文献
994.
36 left-handed and 36 right-handed kindergarten children were asked to print after seeing a series of reversible letters and numbers presented individually on slides or flash cards. Regardless of handedness, both groups of Ss found the left–right orientation cues of the same letters and numbers difficult to recall. This challenges a proposal expressed in the "grammar of action" that claims that certain reversal errors in children's printing result from the inappropriate application of the horizontal motor rule, because although left- and right-handed children use this rule, they do so in different ways and therefore should have produced different errors. Another sample of 86 right-handed children from nursery school through Grade 1 was given the same printing task. Findings from this 2nd sample provide an additional challenge to the grammar of action by showing that reversals of the letter N, which are also thought to result from a misapplication of motor rules, decrease in frequency along with reversals of other letters and numbers, instead of increasing as predicted, during the developmental period when the motor rules that are said to be responsible for reversals of this particular letter become more strongly established. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
995.
996.
997.
998.
采用二维数学模型对漕河洪泛区进行了模拟计算,分析漕河大桥建设对河道防洪产生的影响,同时分析大桥自身的设防标准是否满足要求,并提出可行的肪治与补救措施,为项目审批和建设提供了有力的科学依据。 相似文献
999.
以越南湄公河支流入海口火力发电厂循环水泵房的深基坑工程为例,分析得出沿海基坑工程土质类型基本特点为含水量高,强度小,基岩深度大,结构受到土体物理力学性能影响大;深基坑开挖引起围护结构侧向变形、基坑底部隆起以及开挖后引起地面沉降,变形量受开挖深度、围护方式等因素的影响;水位下降引起土体应力重分布,产生主、被动土压力以及渗透力;沿海深基坑工程适宜采用格构式布置水泥搅拌桩或排桩+钢筋混凝土内支撑进行围护。 相似文献
1000.