全文获取类型
收费全文 | 147468篇 |
免费 | 6787篇 |
国内免费 | 3748篇 |
专业分类
电工技术 | 4694篇 |
技术理论 | 3篇 |
综合类 | 6969篇 |
化学工业 | 21632篇 |
金属工艺 | 8279篇 |
机械仪表 | 6749篇 |
建筑科学 | 7515篇 |
矿业工程 | 2291篇 |
能源动力 | 2706篇 |
轻工业 | 8693篇 |
水利工程 | 2454篇 |
石油天然气 | 4117篇 |
武器工业 | 481篇 |
无线电 | 16989篇 |
一般工业技术 | 23802篇 |
冶金工业 | 5722篇 |
原子能技术 | 954篇 |
自动化技术 | 33953篇 |
出版年
2024年 | 399篇 |
2023年 | 1427篇 |
2022年 | 2353篇 |
2021年 | 3234篇 |
2020年 | 2317篇 |
2019年 | 1889篇 |
2018年 | 16232篇 |
2017年 | 15450篇 |
2016年 | 11774篇 |
2015年 | 3245篇 |
2014年 | 3568篇 |
2013年 | 4201篇 |
2012年 | 7144篇 |
2011年 | 13658篇 |
2010年 | 11953篇 |
2009年 | 9030篇 |
2008年 | 10220篇 |
2007年 | 11121篇 |
2006年 | 3445篇 |
2005年 | 4060篇 |
2004年 | 3117篇 |
2003年 | 2987篇 |
2002年 | 2387篇 |
2001年 | 1719篇 |
2000年 | 1577篇 |
1999年 | 1571篇 |
1998年 | 1300篇 |
1997年 | 1083篇 |
1996年 | 1054篇 |
1995年 | 781篇 |
1994年 | 693篇 |
1993年 | 470篇 |
1992年 | 421篇 |
1991年 | 333篇 |
1990年 | 238篇 |
1989年 | 206篇 |
1988年 | 169篇 |
1987年 | 120篇 |
1986年 | 99篇 |
1985年 | 66篇 |
1984年 | 63篇 |
1983年 | 38篇 |
1982年 | 46篇 |
1968年 | 45篇 |
1966年 | 44篇 |
1965年 | 46篇 |
1959年 | 39篇 |
1957年 | 37篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
EP和GEMM是科学计算领域中常用的计算核心,并广泛应用于高性能计算机体系结构的性能评测.基于一种当今热门的体系结构--流体系结构,设计实现了这两个测试程序在FT64并行系统上的并行算法,并取得了很好的效果. 相似文献
992.
SoC上的晶体管集成度在不断增长,系统功能越来越复杂,传统的设计方法已经不再适应现在的SoC设计.为了解决这种不适应性带来的"硬件危机",人们初步探索将软件中的面向对象技术引入到SoC设计领域中.设计模式是面向对象技术的核心,可以给同类问题提供比较合理的解决方案.在对软件中的设计模式进行分析的基础上,将用于SoC中的CPU指令译码模块进行基于模式的设计,并给出了部分实现. 相似文献
993.
ZhiMing Zheng ShiLong Ma Wei Li Wei Wei Xin Jiang ZhanLi Zhang BingHui Guo 《中国科学F辑(英文版)》2009,52(8):1328-1334
Developing trusted softwares has become an important trend and a natural choice in the development of software technology
and applications, and software trustworthiness modeling has become a prerequisite and necessary means. To discuss and explain
the basic scientific problems in software trustworthiness and to establish theoretical foundations for software trustworthiness
measurement, combining the ideas of dynamical system study, this paper studies evolutionary laws of software trustworthiness
and the dynamical mechanism under the effect of various internal and external factors, and proposes dynamical models for software
trustworthiness, thus, software trustworthiness can be considered as the statistical characteristics of behaviors of software
systems in the dynamical and open environment. By analyzing two simple examples, the paper explains the relationship between
the limit evolutionary behaviors of software trustworthiness attributes and dynamical system characteristics, and interprets
the dynamical characteristics of software trustworthiness and their evolutionary complexity.
Supported partially by the National Basic Research Program of China (Grant No. 2005CB321900) and the National Natural Science
Foundation of China (Grant No. 60473091) 相似文献
994.
Sampled-data based average consensus with measurement noises: convergence analysis and uncertainty principle 总被引:1,自引:0,他引:1
In this paper, sampled-data based average-consensus control is considered for networks consisting of continuous-time first-order
integrator agents in a noisy distributed communication environment. The impact of the sampling size and the number of network
nodes on the system performances is analyzed. The control input of each agent can only use information measured at the sampling
instants from its neighborhood rather than the complete continuous process, and the measurements of its neighbors’ states
are corrupted by random noises. By probability limit theory and the property of graph Laplacian matrix, it is shown that for
a connected network, the static mean square error between the individual state and the average of the initial states of all
agents can be made arbitrarily small, provided the sampling size is sufficiently small. Furthermore, by properly choosing
the consensus gains, almost sure consensus can be achieved. It is worth pointing out that an uncertainty principle of Gaussian
networks is obtained, which implies that in the case of white Gaussian noises, no matter what the sampling size is, the product
of the steady-state and transient performance indices is always equal to or larger than a constant depending on the noise
intensity, network topology and the number of network nodes. 相似文献
995.
Recently, international academic circles advanced a class of new stochastic control models of a geometric Brownian motion
which is an important kind of impulse control models whose cost structure is different from the others before, and it has
a broad applying background and important theoretical significance in financial control and management of investment. This
paper generalizes substantially the above stochastic control models under quite extensive conditions and describes the models
more exactly under more normal theoretical system of stochastic process. By establishing a set of proper variational equations
and proving the existence of its solution, and applying the means of stochastic analysis, this paper proves that the generalized
stochastic control models have optimal controls. Meanwhile, we also analyze the structure of optimal controls carefully. Besides,
we study the solution function of variational equations in a relatively deep-going way, which constitutes the value function
of control models to some extent. Because the analysis methods of this paper are greatly different from those of original
reference, this paper possesses considerable originality to some extent. In addition, this paper gives the strict proof to
the part of original reference which is not fairly well-knit in analyses, and makes analyses and discussions of the model
have the exactitude of mathematical sense.
Supported by the National Natural Science Foundation of China (Grant No. 19671004) 相似文献
996.
This paper reports on recent results in a series of the work of the authors on the stability and nonlinear control for general
dynamical systems described by retarded functional differential and difference equations. Both internal and external stability
properties are studied. The corresponding Lyapunov and Razuminkhin characterizations for input-to-state and input-to-output
stabilities are proposed. Necessary and sufficient Lyapunov-like conditions are derived for robust nonlinear stabilization.
In particular, an explicit controller design procedure is developed for a new class of nonlinear time-delay systems. Lastly,
sufficient assumptions, including a small-gain condition, are presented for guaranteeing the input-to-output stability of
coupled systems comprised of retarded functional differential and difference equations. 相似文献
997.
With its advantages in wirelength reduction and routing flexibility compared with conventional Manhattan routing, X architecture
has been proposed and applied to modern IC design. As a critical part in high-performance integrated circuits, clock network
design meets great challenges due to feature size decrease and clock frequency increase. In order to eliminate the delay and
attenuation of clock signal introduced by the vias, and to make it more tolerant to process variations, in this paper, we
propose an algorithm of a single layer zero skew clock routing in X architecture (called Planar-CRX). Our Planar-CRX method
integrates the extended deferred-merge embedding algorithm (DME-X, which extends the DME algorithm to X architecture) with
modified Ohtsuki’s line-search algorithm to minimize the total wirelength and the bends. Compared with planar clock routing
in the Manhattan plane, our method achieves a reduction of 6.81% in total wirelength on average and gets the resultant clock
tree with fewer bends. Experimental results also indicate that our solution can be comparable with previous non-planar zero
skew clock routing algorithm.
Supported in part by the National Natural Science Foundation of China (Grant No. 60876026), and the Specialized Research Fund
for the Doctoral Program of Higher Education (Crant No. 200800030026) 相似文献
998.
Spirals are curves with one-signed, monotone increasing or decreasing curvature. They are commonly useful in a variety of applications, either for aesthetic or for engineering requirements. In this paper we propose a new iterative subdivision scheme for generating planar spiral segments from two points and their tangent vectors. The subdivision process consists of two main steps, computing new points and adjusting tangent vectors adaptively for each iteration. We categorize this iterative scheme as geometry... 相似文献
999.
High fidelity repeater false-target badly affects a radar system’s detecting, tracking, and data processing. It is an available approach of confronting false-target for radar that discriminates firstly and then eliminates. Whereas for the technique progress about the repeater false-target jam, it is more and more difficult to discriminate this jam in the time-domain, frequency-domain, or space-domain. The technique using polarization information to discriminate the target and false-target is discussed in th... 相似文献
1000.
This paper investigates the controllability of multi-agent systems based on agreement protocols. First, for a group of single-integrator
agents, the controllability is studied in a unified framework for both networks with leader-following structure and networks
with undirected graph. Some new necessary/sufficient conditions for the controllability of networks of single-integrator agents
are established. Second, we prove that, under the same topology and same prescribed leaders, a network of high-order dynamic
agents is completely controllable if and only if so is a network of single-integrator agents. Third, how the selection of
leaders and the coupling weights of graphs affect the controllability is analyzed. Finally, some numerical simulations are
presented to demonstrate the effectiveness of the theoretical results. 相似文献