全文获取类型
收费全文 | 13309篇 |
免费 | 1022篇 |
国内免费 | 1459篇 |
专业分类
电工技术 | 365篇 |
综合类 | 1092篇 |
化学工业 | 135篇 |
金属工艺 | 186篇 |
机械仪表 | 939篇 |
建筑科学 | 489篇 |
矿业工程 | 160篇 |
能源动力 | 62篇 |
轻工业 | 111篇 |
水利工程 | 107篇 |
石油天然气 | 73篇 |
武器工业 | 61篇 |
无线电 | 1251篇 |
一般工业技术 | 292篇 |
冶金工业 | 124篇 |
原子能技术 | 169篇 |
自动化技术 | 10174篇 |
出版年
2024年 | 6篇 |
2023年 | 27篇 |
2022年 | 61篇 |
2021年 | 93篇 |
2020年 | 118篇 |
2019年 | 97篇 |
2018年 | 104篇 |
2017年 | 137篇 |
2016年 | 221篇 |
2015年 | 286篇 |
2014年 | 615篇 |
2013年 | 749篇 |
2012年 | 877篇 |
2011年 | 1056篇 |
2010年 | 1044篇 |
2009年 | 1157篇 |
2008年 | 1383篇 |
2007年 | 1475篇 |
2006年 | 1398篇 |
2005年 | 1177篇 |
2004年 | 984篇 |
2003年 | 805篇 |
2002年 | 592篇 |
2001年 | 474篇 |
2000年 | 352篇 |
1999年 | 188篇 |
1998年 | 85篇 |
1997年 | 53篇 |
1996年 | 29篇 |
1995年 | 19篇 |
1994年 | 13篇 |
1993年 | 17篇 |
1992年 | 6篇 |
1991年 | 16篇 |
1990年 | 12篇 |
1989年 | 11篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 11篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
《无线互联科技》2015,(24)
文章主要介绍了实现机票预订系统的管理过程,该设计的完成也切实的体现了系统管理实施的优点。首先让大家了解了该系统开发的背景、研究现状及其发展趋势,让读者清楚设计该系统的目的及意义。然后较为详细地叙述了系统设计的可行性分析、需求分析、概要设计和功能的实现,其中主要以技术可行性和功能需求为主要叙述对象。最后把系统测试的方法和设计该系统出现的问题及修改完善的方法加以说明让大家更好的了解设计的过程。系统的功能主要包括基本的查询系统、订票系统、退票系统;主要的工作处理包括机票预订处理和退票处理;信息资料查询主要是管理员对客户信息查询、用户对航班信息查询、机票预定查询和退票信息查询;这些功能都满足了客户对机票预订系统的使用需求和对信息检索的要求。 相似文献
2.
This paper deals with three-dimensional non-linear finite element analyses to assess the structural behavior of adhesively-bonded double supported tee joint of laminated FRP composites having embedded interfacial failures. The onset of interfacial failures is predicted by using Tsai–Wu coupled stress failure criterion with pre-determined stress values. The concept of fracture mechanics principle is utilized to study the sustainability of the tee joint having interfacial failures pre-existed at the critical locations. Individual modes of the strain energy release rates (SERR) GI, GII and GIII, are considered as the damage growth parameters and, are evaluated using the Modified crack closure integral (MCCI) technique based on the concept of linear elastic fracture mechanics (LEFM). Based on the stress analyses, it has been observed that the interfacial failures in tee joint structure trigger at the interface of base plate and adhesive layer from both ends of base plate. Depending on the SERR magnitudes, it has been noticed that the interfacial failure propagates under mixed mode condition. Therefore total SERR (GT) is considered as the governing parameter for damage propagation. Furthermore, efforts have been made to retard damage propagation rate by employing functionally graded adhesive (FGA) instead of monolithic adhesive material. Series of numerical simulations have been performed for varied interfacial failure length in functionally graded adhesively bonded double supported tee joint structure in order to achieve the significant effect of FGA with various modulus ratios on SERR. Material gradation of adhesive indicates significant SERR reduction at the incipient stage of failure which necessitates the use of functionally graded adhesive for the tee joint and prolong the service life of the structure. 相似文献
3.
4.
Chih-Ming Chen Hahn-Ming Lee Chia-Chen Tan 《Engineering Applications of Artificial Intelligence》2006,19(8):967-978
The explosion of on-line information has given rise to many manually constructed topic hierarchies (such as Yahoo!!). But with the current growth rate in the amount of information, manual classification in topic hierarchies results in an immense information bottleneck. Therefore, developing an automatic classifier is an urgent need. However, classifiers suffer from enormous dimensionality, since the dimensionality is determined by the number of distinct keywords in a document corpus. More seriously, most classifiers are either working slowly or they are constructed subjectively without any learning ability. In this paper, we address these problems with a fair feature-subset selection (FFSS) algorithm and an adaptive fuzzy learning network (AFLN) for classification. The FFSS algorithm is used to reduce the enormous dimensionality. It not only gives fair treatment to each category but also has ability to identify useful features, including both positive and negative features. On the other hand, the AFLN provides extremely fast learning ability to model the uncertain behavior for classification so as to correct the fuzzy matrix automatically. Experimental results show that both FFSS algorithm and the AFLN lead to a significant improvement in document classification, compared to alternative approaches. 相似文献
5.
基于ERP系统的电子商务平台的分析 总被引:2,自引:1,他引:1
提出了利用DNA和XML技术构建基于ERP系统的电子商务平台的解决方案,并且给出了数据接口的几种实现方式。 相似文献
6.
根据惠斯通电桥工作原理,采用回路法可以简便快捷地确定电视地下电缆接地、短路故障点的位置。电容法也是一种常用的检查开路的检测方法。这样维修人员可以迅速排除故障,保证电视节目的正常传送。 相似文献
7.
Steel box sections are usually fabricated from flat plates which are welded at the corners. The welding process can introduce residual stresses and geometric imperfections into the sections which can influence their strength. For some thin-walled sections, large periodic geometric imperfections have been observed in manufactured sections. Subsequent investigations have indicated that the imperfections are in fact buckling deformations i.e. the box section has buckled due to welding residual stresses prior to any application of external load. The welding procedure and the behaviour of the box sections under load has been modelled using a finite element analysis that accounts for both geometric and material non-linearities. Tests have been carried out on box sections with a range of width to thickness ratios for the plate elements. Modelling has been shown to give good correlation with the test results. The conditions for buckling to take place as a result of the welding process have been established. A design method has been proposed. 相似文献
8.
Web型课件的开发与应用 总被引:2,自引:0,他引:2
分析了Web型课件的优点及功能,并针对Web型课件的开发和应用进行了初步研究。 相似文献
9.
Although the literature on the mechanics of cellular materials is vast, there is no theoretical model to account for the effects of axial yielding of struts aligned to the applied loading direction on the plastic yield surface under multiaxial loading conditions. An anisotropic hexagonal model having tapered strut morphology is developed to show these effects on the plastic yield surface under multiaxial tensile loading condition. This model covers several types of cellular structure such as two-dimensional (2D) hexagonal and square cellular materials, and three-dimensional (3D) hexagonal and rhombic cellular materials of rod-like columnar structure. A tetrahedral element with tapered strut morphology is also used for a foam model to illustrate these effects on the yield surface under axisymmetric loading condition. Plastic collapse due to bending moment in the inclined struts is a dominant mode. However, under multiaxial tensile loading, the collapse due to axial yielding of struts parallel to the loading direction is found to be an important mode. The shape of plastic yield surface was found to depend not only on relative density but also on the strut morphology. 相似文献
10.
加强交叉铺网机控制的探讨 总被引:5,自引:1,他引:4
介绍了比利时OCTIR公司LF36型交叉铺网机的基本原理,并总结了对其安装、调试及纤网控制的心得体会。 相似文献