全文获取类型
收费全文 | 22722篇 |
免费 | 2238篇 |
国内免费 | 1391篇 |
专业分类
电工技术 | 2067篇 |
综合类 | 2021篇 |
化学工业 | 2392篇 |
金属工艺 | 1366篇 |
机械仪表 | 2796篇 |
建筑科学 | 3853篇 |
矿业工程 | 1748篇 |
能源动力 | 560篇 |
轻工业 | 1227篇 |
水利工程 | 774篇 |
石油天然气 | 469篇 |
武器工业 | 170篇 |
无线电 | 1872篇 |
一般工业技术 | 2460篇 |
冶金工业 | 879篇 |
原子能技术 | 125篇 |
自动化技术 | 1572篇 |
出版年
2024年 | 102篇 |
2023年 | 355篇 |
2022年 | 514篇 |
2021年 | 669篇 |
2020年 | 789篇 |
2019年 | 586篇 |
2018年 | 609篇 |
2017年 | 680篇 |
2016年 | 757篇 |
2015年 | 878篇 |
2014年 | 1437篇 |
2013年 | 1406篇 |
2012年 | 1624篇 |
2011年 | 1673篇 |
2010年 | 1310篇 |
2009年 | 1428篇 |
2008年 | 1311篇 |
2007年 | 1710篇 |
2006年 | 1469篇 |
2005年 | 1245篇 |
2004年 | 997篇 |
2003年 | 869篇 |
2002年 | 722篇 |
2001年 | 577篇 |
2000年 | 519篇 |
1999年 | 394篇 |
1998年 | 362篇 |
1997年 | 300篇 |
1996年 | 233篇 |
1995年 | 174篇 |
1994年 | 148篇 |
1993年 | 108篇 |
1992年 | 93篇 |
1991年 | 66篇 |
1990年 | 56篇 |
1989年 | 36篇 |
1988年 | 32篇 |
1987年 | 22篇 |
1986年 | 9篇 |
1985年 | 15篇 |
1984年 | 17篇 |
1983年 | 5篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 12篇 |
1977年 | 4篇 |
1966年 | 2篇 |
1959年 | 3篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
81.
R. A. SMITH 《Fatigue & Fracture of Engineering Materials & Structures》2003,26(10):901-907
The importance of the wheel–rail interface to the safe operation of railways is discussed. Some aspects of the history of rails and wheels are introduced. Several recent accidents involving the wheel–rail interface are described. The great importance of operating both vehicles and track as a system is emphasized, together with the necessity of maintaining both in good condition. 相似文献
82.
贵金属及其合金铆钉型复合电触点除了应考核其冷态复合强度之外,还必须增加在热态下复合强度的考核,只有这样才能满足用户在产际运行时对复合触点复合强度的要求。 相似文献
83.
J. Gegner Priv.‐Doz. Dr. W. Nierlich M. Brückner 《Materialwissenschaft und Werkstofftechnik》2007,38(8):613-623
Due to clearly distinguishable damage symptoms, it is differentiated between the surface and sub‐surface failure mode of rolling bearings. Material states red out by X‐ray diffraction (XRD) residual stress measurements point to a variety of loading conditions especially at raceway surfaces that are associated with several competing failure mechanisms. The corresponding lifetime reduction can range from the lower fatigue strength region to material ratcheting in extreme cases. Relevant position of the microstructural changes and nature of the failure mechanisms are characterized. The time alteration of the XRD material parameters measured at or near the surface and at the depth of the maximum equivalent stress correlates, in a different manner, with the statistical parameter of the 10 % bearing life. Both failure modes are illustrated by concrete examples. Contaminated lubricant and boundary lubrication, which represent practically important surface‐induced failures, are discussed in more detail. Gray staining, i.e. shallow pitting, often occurs without distinct indication of global material aging by means of XRD characteristics. Here, scanning electron microscopy observations and electron microprobe analyses point to corrosion fatigue as acting surface failure mechanism. The interaction between material and lubricant under complex loading regimes particularly of mixed friction and corrosion opens further failure research areas in the field of tribology. 相似文献
84.
Jaroslav Mackerle 《International Journal of Pressure Vessels and Piping》1996,69(3):279-339
The paper gives a bibliographical review of the finite element methods (FEMs) applied for the analysis of pressure vessel structures/components and piping from the theoretical as well as practical points of view. The range of applications of FEMs in this area is wide and cannot be presented in a single paper; therefore the aim of this review is to give the reader an encyclopaedic view of the differnt possibilities that exist today for the finite element analysis in the fields of pressure vessels and piping. The bibliography at the end of the paper contains approximately 1900 references to papers, conference proceedings and theses/dissertations on the subject that were published in 1976–1996. These are classified in the following categories: linear and non-linear, static and dynamic, stress and deflection analysis; stability problems; thermal problems; fracture mechanics problems; contact problems; fluid-structure interaction problems; manufacturing of pipes and tubes; welded pipes and pressure vessel components; development of special finite elements for pressure vessels and pipes; finite element software; and other topics. Also finite element software, general purpose and special purpose codes, used for the analysis of pressure vessels and pipes are briefly discussed and presented. 相似文献
85.
86.
采用Ge/Pd/GaAs结构和快速热退火在n-GaAs上形成了低阻欧姆接触。利用H次离子质谱(SIMS)技术揭示和讨论了低欧姆接触形成的机理。比较了采用X 和CsX 信号检测的Ge,Pd,Ga和As的深度分布。结果表明采用CSX 可以提供更准确的结果和成分信息。 相似文献
87.
A roll-coating experimental system is used to study the effect of pre-wetting on dynamic contact angles, the interfacial displacement depth, and the associated phenomenon of air entrainment. The system consists of a roll, which is horizontally rotating in a liquid pool. The dynamic contact angle is recorded by a macrophotography system. The test liquids are glycerol solutions with viscosities in the range 104 < μ < 748 mPa · s. The value of (μV/ρg)0.5 is taken as the characteristic length to be used in the dimensionless relationships which correlate experimental measurements. The effect of base layer entry angle into the liquid pool on the dynamic contact angles and other flow parameters is studied. Comparison is made with measurements in dry tape-coating and other pre-wet roll–coating systems. 相似文献
88.
89.
高速公路各种软基处理工后沉降的试验研究和分析 总被引:6,自引:0,他引:6
从地质条件、软基处理和现场试验等几方面,对排水固结法中的超载预压和真空预压,复合地基法中的粉喷桩和CFG桩等处理的效果进行了系统的试验研究和分析,为类似工程提供了可借鉴的经验。 相似文献
90.
A.P.S. Selvadurai 《International Journal of Engineering Science》2003,41(7):721-739
This paper examines the axisymmetric elastostatic problem related to the unilateral receding contact at a pre-compressed smooth bimaterial elastic interface. The separation at the interface is caused by the action of axisymmetric stress fields of unequal magnitude, which are applied at any location of the separate halfspace regions. The analysis of the problem focuses on the determination of the zone of separation as a function of the pre-compression, the magnitudes and locations of the axisymmetric stress fields inducing the separation, and the elasticity characteristics of the halfspace regions. It is found that the radius of the separation zone can be evaluated in explicit form. In the particular instance when the loadings applied at the surface of the halfspace regions are equal in magnitude and distribution, the analysis reveals that the radius of the separation zone is independent of the elasticity properties of the halfspace regions and can be evaluated in exact closed form. 相似文献