全文获取类型
收费全文 | 41885篇 |
免费 | 4317篇 |
国内免费 | 2530篇 |
专业分类
电工技术 | 3808篇 |
技术理论 | 2篇 |
综合类 | 3310篇 |
化学工业 | 5618篇 |
金属工艺 | 2494篇 |
机械仪表 | 2304篇 |
建筑科学 | 3258篇 |
矿业工程 | 1489篇 |
能源动力 | 4325篇 |
轻工业 | 1521篇 |
水利工程 | 1001篇 |
石油天然气 | 2002篇 |
武器工业 | 389篇 |
无线电 | 5461篇 |
一般工业技术 | 6006篇 |
冶金工业 | 1526篇 |
原子能技术 | 722篇 |
自动化技术 | 3496篇 |
出版年
2024年 | 200篇 |
2023年 | 708篇 |
2022年 | 1235篇 |
2021年 | 1412篇 |
2020年 | 1531篇 |
2019年 | 1288篇 |
2018年 | 1232篇 |
2017年 | 1537篇 |
2016年 | 1601篇 |
2015年 | 1705篇 |
2014年 | 2634篇 |
2013年 | 2785篇 |
2012年 | 2989篇 |
2011年 | 3584篇 |
2010年 | 2639篇 |
2009年 | 2789篇 |
2008年 | 2549篇 |
2007年 | 2568篇 |
2006年 | 2228篇 |
2005年 | 1822篇 |
2004年 | 1575篇 |
2003年 | 1422篇 |
2002年 | 1188篇 |
2001年 | 891篇 |
2000年 | 791篇 |
1999年 | 646篇 |
1998年 | 508篇 |
1997年 | 441篇 |
1996年 | 417篇 |
1995年 | 311篇 |
1994年 | 301篇 |
1993年 | 215篇 |
1992年 | 179篇 |
1991年 | 181篇 |
1990年 | 140篇 |
1989年 | 109篇 |
1988年 | 67篇 |
1987年 | 59篇 |
1986年 | 46篇 |
1985年 | 40篇 |
1984年 | 40篇 |
1983年 | 29篇 |
1982年 | 30篇 |
1981年 | 20篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1959年 | 6篇 |
1955年 | 3篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
921.
针对武器电子系统质量评估过程中客观性不强、实用度较差的问题,引入评估指标的区分度与重要度概念,提出基于DSmT改进权值的TOPSIS质量评估方法;首先,从主客观角度构建指标重要度和区分度作为广义信度赋值;然后采用DSmT(Dezert-Smarandache Theory)理论融合不同冲突证据源的广义信度赋值,消除证据源间的冲突,得到改进权值;接着构造基于改进权值的TOPSIS(Technique for Order Preference by Similarity to an Ideal Solution)法隶属贴近度;最后,以某型感应装定器为例进行实验验证,结果表明,该方法确定的指标权重具有更高可信度,对系统的质量评估更加准确,符合装备实际情况,具有较好的工程应用价值。 相似文献
922.
针对现有眩光效果绘制方法的真实感和速度问题,提出一种基于GPU的真实感眩光效果绘制方法.首先根据光圈和镜头生成带有随机镜头噪声的二维衍射光栅图像;其次考虑夫琅禾费和菲涅耳2种不同的衍射效果,利用预存算法系数的快速傅里叶变换模拟衍射效果的光学过程,并通过衍射效果的光谱模型实现真实感绘制,同时利用2个独立的一维高斯卷积核加速实现bloom效果;再通过随机小角度旋转和混合操作进行真实感增强;最后采用实时光线跟踪渲染框架,在三维场景中实现了真实感眩光效果的实时绘制.该方法的主要步骤采用CUDA实现,充分利用了GPU强大的并行计算能力并兼顾考虑存储器优化策略.实验结果表明,文中方法绘制结果具有较强的真实感和实时性. 相似文献
923.
为提高摆线泵的容积效率,优化泵内部的流场分布,减少回流和空化现象.利用CFD方法对摆线泵内部流场进行数值模拟,定量分析月牙状进出油腔对泵容积效率的影响.仿真结果表明,适当减小G0并增大F0可以改善泵的内部流场分布,提高容积效率.仿真结果可以为摆线泵的结构设计提供参考. 相似文献
924.
张俊 《电脑编程技巧与维护》2013,(8):113-114
介绍了硬盘保护系统的主要功能和在计算机实验室的实际应用,阐述了硬盘分区规划、实验室机器IP地址的自动分配、硬盘保护系统的使用技巧。 相似文献
925.
926.
927.
928.
AutoCAD软件由于其强大的绘制功能,目前已经广泛应用于各个行业领域,但是如果对一些技巧应用得当就会使绘图效率提高很多,起到事半功倍的效果。就AutoCAD的表格制作、对象的选择,点划线的显示以及快捷命令的应用等作了一些探索。 相似文献
929.
余建军 《中国水能及电气化》2011,(10):47-49,46
本文针对目前每个小型水电站扩容增效技改中微机监控设计和改造中必须解决的同期点选择和同期方式确定问题结合相关理论、规范,在总结常规监控方式下同类问题的解决办法基础上结合工程实际提出了切实可行解决问题的方法和依据。 相似文献
930.
Andrzej Daniluk 《Computer Physics Communications》2011,182(6):1389-1390
A computational model is a computer program, which attempts to simulate an abstract model of a particular system. Computational models use enormous calculations and often require supercomputer speed. As personal computers are becoming more and more powerful, more laboratory experiments can be converted into computer models that can be interactively examined by scientists and students without the risk and cost of the actual experiments. The future of programming is concurrent programming. The threaded programming model provides application programmers with a useful abstraction of concurrent execution of multiple tasks. The objective of this release is to address the design of architecture for scientific application, which may execute as multiple threads execution, as well as implementations of the related shared data structures.
New version program summary
Program title: GrowthCPCatalogue identifier: ADVL_v4_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADVL_v4_0.htmlProgram obtainable from: CPC Program Library, Queen?s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 32 269No. of bytes in distributed program, including test data, etc.: 8 234 229Distribution format: tar.gzProgramming language: Free Object PascalComputer: multi-core x64-based PCOperating system: Windows XP, Vista, 7Has the code been vectorised or parallelized?: NoRAM: More than 1 GB. The program requires a 32-bit or 64-bit processor to run the generated code. Memory is addressed using 32-bit (on 32-bit processors) or 64-bit (on 64-bit processors with 64-bit addressing) pointers. The amount of addressed memory is limited only by the available amount of virtual memory.Supplementary material: The figures mentioned in the “Summary of revisions” section can be obtained here.Classification: 4.3, 7.2, 6.2, 8, 14External routines: Lazarus [1]Catalogue identifier of previous version: ADVL_v3_0Journal reference of previous version: Comput. Phys. Comm. 181 (2010) 709Does the new version supersede the previous version?: YesNature of problem: Reflection high-energy electron diffraction (RHEED) is an important in-situ analysis technique, which is capable of giving quantitative information about the growth process of thin layers and its control. It can be used to calibrate growth rate, analyze surface morphology, calibrate surface temperature, monitor the arrangement of the surface atoms, and provide information about growth kinetics. Such control allows the development of structures where the electrons can be confined in space, giving quantum wells or even quantum dots. In order to determine the atomic positions of atoms in the first few layers, the RHEED intensity must be measured as a function of the scattering angles and then compared with dynamic calculations. The objective of this release is to address the design of architecture for application that simulates the rocking curves RHEED intensities during hetero-epitaxial growth process of thin films.Solution method: The GrowthCP is a complex numerical model that uses multiple threads for simulation of epitaxial growth of thin layers. This model consists of two transactional parts. The first part is a mathematical model being based on the Runge–Kutta method with adaptive step-size control. The second part represents first-principles of the one-dimensional RHEED computational model. This model is based on solving a one-dimensional Schrödinger equation. Several problems can arise when applications contain a mixture of data access code, numerical code, and presentation code. Such applications are difficult to maintain, because interdependencies between all the components cause strong ripple effects whenever a change is made anywhere. Adding new data views often requires reimplementing a numerical code, which then requires maintenance in multiple places. In order to solve problems of this type, the computational and threading layers of the project have been implemented in the form of one design pattern as a part of Model-View-Controller architecture.Reasons for new version: Responding to the users? feedback the Growth09 project has been upgraded to a standard that allows the carrying out of sample computations of the RHEED intensities for a disordered surface for a wide range of single- and epitaxial hetero-structures. The design pattern on which the project is based has also been improved. It is shown that this model can be effectively used for multithreaded growth simulations of thin epitaxial layers and corresponding RHEED intensities for a wide range of single- and hetero-structures. Responding to the users? feedback the present release has been implemented using a well-documented free compiler [1] not requiring the special configuration and installation additional libraries.Summary of revisions:1.
The logical structure of the Growth09 program has been modified according to the scheme showed in Fig. 1.1 The class diagram in Fig. 11 is a static view of the main platform-specific elements of the GrowthCP architecture. Fig. 21 provides a dynamic view by showing the creation and destruction simplistic sequence diagram for the process. 2.
The program requires the user to provide the appropriate parameters in the form of a knowledge base for the crystal structures under investigation. These parameters are loaded from the parameters.ini files at run-time. Instructions to prepare the .ini files can be found in the new distribution. 3.
The program enables carrying out different growth models and one-dimensional dynamical RHEED calculations for the fcc lattice with basis of three-atoms, fcc lattice with basis of two-atoms, fcc lattice with single atom basis, Zinc-Blende, Sodium Chloride, and Wurtzite crystalline structures and hetero-structures, but yet the Fourier component of the scattering potential in the TRHEEDCalculations.crystPotUgXXX() procedure can be modified and implemented according to users? specific application requirements. The Fourier component of the scattering potential of the whole crystalline hetero-structures can be determined as a sum of contributions coming from all thin slices of individual atomic layers. To carry out one-dimensional calculations of the scattering potentials, the program uses properly constructed self-consistent procedures. 4.
Each component of the system shown in Figs. 11 and 21 is fully extendable and can easily be adapted to new changeable requirements. Two essential logical elements of the system, i.e. TGrowthTransaction and TRHEEDCalculations classes, were designed and implemented in this way for them to pass the information to themselves without the need to use the data-exchange files given. In consequence each of them can be independently modified and/or extended. Implementing other types of differential equations and the different algorithm for solving them in the TGrowthTransaction class does not require another implementation of the TRHEEDCalculations class. Similarly, implementing other forms of scattering potential and different algorithm for RHEED calculation stays without the influence on the TGrowthTransaction class construction.
[1]
http://sourceforge.net/projects/lazarus/files/.