全文获取类型
收费全文 | 22367篇 |
免费 | 2111篇 |
国内免费 | 1522篇 |
专业分类
电工技术 | 1554篇 |
技术理论 | 1篇 |
综合类 | 1960篇 |
化学工业 | 1751篇 |
金属工艺 | 2029篇 |
机械仪表 | 1598篇 |
建筑科学 | 2427篇 |
矿业工程 | 586篇 |
能源动力 | 366篇 |
轻工业 | 261篇 |
水利工程 | 816篇 |
石油天然气 | 612篇 |
武器工业 | 257篇 |
无线电 | 3146篇 |
一般工业技术 | 2947篇 |
冶金工业 | 466篇 |
原子能技术 | 198篇 |
自动化技术 | 5025篇 |
出版年
2024年 | 88篇 |
2023年 | 344篇 |
2022年 | 483篇 |
2021年 | 592篇 |
2020年 | 586篇 |
2019年 | 561篇 |
2018年 | 478篇 |
2017年 | 606篇 |
2016年 | 612篇 |
2015年 | 722篇 |
2014年 | 1334篇 |
2013年 | 1330篇 |
2012年 | 1558篇 |
2011年 | 1574篇 |
2010年 | 1251篇 |
2009年 | 1286篇 |
2008年 | 1266篇 |
2007年 | 1571篇 |
2006年 | 1413篇 |
2005年 | 1280篇 |
2004年 | 1088篇 |
2003年 | 998篇 |
2002年 | 815篇 |
2001年 | 709篇 |
2000年 | 617篇 |
1999年 | 469篇 |
1998年 | 441篇 |
1997年 | 359篇 |
1996年 | 296篇 |
1995年 | 258篇 |
1994年 | 210篇 |
1993年 | 210篇 |
1992年 | 145篇 |
1991年 | 93篇 |
1990年 | 82篇 |
1989年 | 70篇 |
1988年 | 51篇 |
1987年 | 18篇 |
1986年 | 30篇 |
1985年 | 25篇 |
1984年 | 19篇 |
1983年 | 12篇 |
1982年 | 12篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 10篇 |
1978年 | 4篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
A general numerical model is described for the dissolution kinetics of spherical particles in binary systems for any combination of first order reactions at the particle-matrix interface and long distance diffusion within the matrix. The model is applicable to both finite and infinite media and handles both complete and partial particle dissolution. It is shown that interfacial reactions can have a strong effect on the dissolution kinetics, the solute concentration at the particle-matrix interface and the solute concentration profile in the matrix. 相似文献
62.
雷震海 《湖南工业职业技术学院学报》2006,6(1):82-83
“佛靠金装,人靠衣装”。封面设计是书籍装帧设计的重要内容。封面设计要体现书的内容、性质、色彩要考虑读书对象、文化层次,装帧设计给人以美的感觉。 相似文献
63.
研究H90-钢-H90反向凝固复合过程中复合层厚度的变化规律以及复合带的组织和性能,探讨界面结合机理。结果表明:随着浸渍时间的增加,复合层的厚度变化经历了凝固生长、平衡相持和回熔3个阶段,钢带的预热温度越低,获得的最大复合层厚度越厚;H90复合层的组织为等轴晶粒,复合界面处Cu和Fe发生了扩散,而Zn未发生明显扩散,扩散层较薄,约为4μm;复合带的界面结合牢固;不同复合层厚度的复合带,其力学性能略有差异,但均达到GB5213——85所规定的F级深冲钢板的力学性能要求。 相似文献
64.
水轮机调速器现代调节技术及选型 总被引:4,自引:4,他引:0
对目前比较先进的微机调速器的两种系统结构进行了分析,并对微机调节的控制策略和调节参数的设置及系统配置等作了介绍,并提出了对凋速器技术性能的评价标准和调速器选型时的突出问题,可为实际应用提供参考。 相似文献
65.
住宅给水铜管分水布置是一种技术可行、经济合理的管道布置方式。在确定了管道的设计要求后,分析了分水缩径后的流速情况,明确了分水布置方式中支管缩径的技术状况。分析表明,支管缩径是可行的。 相似文献
66.
Sven Beyer Christian Jacobi Daniel Kröning Dirk Leinenbach Wolfgang J. Paul 《International Journal on Software Tools for Technology Transfer (STTT)》2006,8(4-5):411-430
In the verified architecture microprocessor (VAMP) project we have designed, functionally verified, and synthesized a processor
with full DLX instruction set, delayed branch, Tomasulo scheduler, maskable nested precise interrupts, pipelined fully IEEE
compatible dual precision floating point unit with variable latency, and separate instruction and data caches. The verification
has been carried out in the theorem proving system PVS. The processor has been implemented on a Xilinx FPGA.
A shorter version of this article with the title “Instantiating uninterpreted functional units and memory system: functional
verification of the VAMP” appeared in [8]. The work reported here was done while all the authors were with Saarland University. 相似文献
67.
杨怀义 《数字社区&智能家居》2006,(14)
网格袋布局管理器是java布局中最有用、最灵活、最复杂、最难掌握的一种布局管理器,实际上,如果我们明白了在布局时它利用了单元格相对坐标定位这一点,以及各个约束条件在布局中的作用,网格袋布局也会变得很轻松。 相似文献
68.
H. Ji D. Chopp J. E. Dolbow 《International journal for numerical methods in engineering》2002,54(8):1209-1233
A hybrid numerical method for modelling the evolution of sharp phase interfaces on fixed grids is presented. We focus attention on two‐dimensional solidification problems, where the temperature field evolves according to classical heat conduction in two subdomains separated by a moving freezing front. The enrichment strategies of the eXtended Finite Element Method (X‐FEM) are employed to represent the jump in the temperature gradient that governs the velocity of the phase boundary. A new approach with the X‐FEM is suggested for this class of problems whereby the partition of unity is constructed with C1(Ω) polynomials and enriched with a C0(Ω) function. This approach leads to jumps in temperature gradient occurring only at the phase boundary, and is shown to significantly improve estimates for the front velocity. Temporal derivatives of the temperature field in the vicinity of the phase front are obtained with a projection that employs discontinuous enrichment. In conjunction with a finer finite difference grid, the Level Set method is used to represent the evolution of the phase interface. An iterative procedure is adopted to satisfy the constraints on the temperature field on the phase boundary. The robustness and utility of the method is demonstrated with several benchmark problems of phase transformation. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
69.
In the late eighties and up to the beginning of nineties computation of turbulent flows is mostly dominated by RANS (Reynolds
Averaged Navier-Stokes Simulation) type modelling. During the last few years URANS (Unsteady RANS) and LES (Large Eddy Simulation)
type of approaches have been attempted with some success. Yet, there have been many difficulties when LES is applied to practical
engineering problems and to high Reynolds number flows as energy dissipating eddies become really small and mesh resolution
required for a reasonably resolved LES approaches that of DNS (Direct Numerical Simulation). An alternative solution suggested
was to combine RANS and LES, which in general referred to as Hybrid LES. There have been many proposals for combining RANS
and LES in different ways. In this article, some of the issues involved in performing hybrid LES reported in the recent literature
is briefly reviewed. 相似文献
70.
Influence of Ni Interlayers on the Mechanical Properties of Ti6Al4V/(WC-Co) Friction Welds 总被引:2,自引:0,他引:2
M. Shamanian M. Salehi A. Saatchi T. H. North 《Materials and Manufacturing Processes》2003,18(4):581-598
Ni interlayers were introduced prior to dissimilar friction welding of Ti6Al4V base material to three cemented carbide substrates. The fracture strength of Ti6Al4V/(WC-6 wt% Co) welds were poor and were markedly improved when 20-µm thick Ni interlayers were introduced prior to dissimilar friction welding. These results were only produced when the (WC-6 wt% Co) cermet was electroplated prior to friction welding. When the Ti6Al4V alloy was electroplated prior to friction welding, fractured WC particles and cracking were observed in the (WC-Co) carbide substrate. The fracture strengths of Ti6Al4V/(WC-11 wt% Co) and Ti6Al4V/(WC-24 wt% Co) welds were not improved when 20-µm thick Ni interlayers were introduced prior to friction welding. During mechanical testing, the Ni layer retained at the dissimilar joint interface created a region of weakness. 相似文献