全文获取类型
收费全文 | 5856篇 |
免费 | 101篇 |
国内免费 | 83篇 |
专业分类
电工技术 | 43篇 |
综合类 | 129篇 |
化学工业 | 666篇 |
金属工艺 | 301篇 |
机械仪表 | 502篇 |
建筑科学 | 944篇 |
矿业工程 | 142篇 |
能源动力 | 259篇 |
轻工业 | 158篇 |
水利工程 | 44篇 |
石油天然气 | 224篇 |
武器工业 | 51篇 |
无线电 | 169篇 |
一般工业技术 | 989篇 |
冶金工业 | 538篇 |
原子能技术 | 48篇 |
自动化技术 | 833篇 |
出版年
2024年 | 6篇 |
2023年 | 82篇 |
2022年 | 95篇 |
2021年 | 144篇 |
2020年 | 117篇 |
2019年 | 107篇 |
2018年 | 110篇 |
2017年 | 136篇 |
2016年 | 152篇 |
2015年 | 165篇 |
2014年 | 279篇 |
2013年 | 316篇 |
2012年 | 283篇 |
2011年 | 501篇 |
2010年 | 362篇 |
2009年 | 338篇 |
2008年 | 358篇 |
2007年 | 345篇 |
2006年 | 273篇 |
2005年 | 248篇 |
2004年 | 246篇 |
2003年 | 220篇 |
2002年 | 176篇 |
2001年 | 102篇 |
2000年 | 127篇 |
1999年 | 144篇 |
1998年 | 129篇 |
1997年 | 111篇 |
1996年 | 65篇 |
1995年 | 61篇 |
1994年 | 57篇 |
1993年 | 39篇 |
1992年 | 26篇 |
1991年 | 21篇 |
1990年 | 20篇 |
1989年 | 17篇 |
1988年 | 13篇 |
1987年 | 11篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有6040条查询结果,搜索用时 15 毫秒
51.
一种新型的多层复合软包装材料 总被引:3,自引:0,他引:3
综述了高阻隔性层合食品软包装的现状及发展趋势。介绍了以PC为结构层的新型多层复合材料PC/EVOH/PP,并评价了它在高阻隔性、高温、高湿、共挤加工等方面的综合性能及用于层含软包装的可行性。 相似文献
52.
Cost estimation of structural skeleton using an interactive automation algorithm: A conceptual approach 总被引:1,自引:0,他引:1
This paper addresses a new concept for generating bills of quantities (B.o.Qs) using AutoCAD drawings for a building project, which demonstrates the application of Industry Foundation Class (IFC), developed by International Alliance for Interoperability (IAI). The procedure considers types of materials and the structural shapes of the AutoCAD drawings to compute the cost of the structural skeleton elements using interactive automation. The main concept focuses on using layer computation of the AutoCAD drawing after converting it into a drawing inter-exchangeable file format (DXF). Once the coordinates are detected, it is easier to determine the area and volume for any structural shape, including circles and polygons. The extracting method is a new technique for structural engineers and quantity surveyors to estimate required material for beam, columns, slabs and foundations. The algorithm extracts and recognizes the layers and objects from a two dimensional DXF drawing along with the coordinates information. The results obtained using this technique are more accurate and reliable than manual procedures or any other traditional techniques. In this paper, an automated and interactive procedure for B.o.Q computation is demonstrated. The process involves a user-friendly interface, dynamic linking to the structural drawings and tracking of B.o.Q modifications at the same time. 相似文献
53.
The twinning of YBa2Cu3O7 (YBCO) thin films with c-axis orientation on (001) MgO, (001) SrTiO3, (012) LaAlO3, (110) NdGaO3 and (001) NdGaO3 substrates, prepared by laser ablation, has been examined using a combination of and θ/2θ scans at a four-circle diffractometer. On all substrates, except for (001) NdGaO3, the tetragonal to orthorhombal phase transition results in four different orientations of YBCO twins relating to the substrate. On (001) NdGaO3 only two different twin orientations, accompanied by a slight lattice monoclinization, has been observed. 相似文献
54.
首先在结构上创造了新型螺栓、螺母和一套崭新的安装机。在主机上去掉了精密、复杂、昂贵的机器人或机械手,改用结构简单的集成齿轮机构,以实现同步旋拧功能;运用现代流体传动与控制的理论,建立流本控制的数学模型和传递函数,从而实现了4个同步安装的效果。 相似文献
55.
A New Approach to Abstract Syntax with Variable Binding 总被引:1,自引:1,他引:0
The permutation model of set theory with atoms (FM-sets), devised by Fraenkel and Mostowski in the 1930s, supports notions
of ‘name-abstraction’ and ‘fresh name’ that provide a new way to represent, compute with, and reason about the syntax of formal
systems involving variable-binding operations. Inductively defined FM-sets involving the name-abstraction set former (together
with Cartesian product and disjoint union) can correctly encode syntax modulo renaming of bound variables. In this way, the
standard theory of algebraic data types can be extended to encompass signatures involving binding operators. In particular,
there is an associated notion of structural recursion for defining syntax-manipulating functions (such as capture avoiding
substitution, set of free variables, etc.) and a notion of proof by structural induction, both of which remain pleasingly
close to informal practice in computer science.
Received October 2000 / Accepted in revised form April 2001 相似文献
56.
Wan Fokkink Rob van Glabbeek Paulien de Wind 《Electronic Notes in Theoretical Computer Science》2006,156(1):97
We present congruence formats for η- and rooted η-bisimulation equivalence. These formats are derived using a method for decomposing modal formulas in process algebra. To decide whether a process algebra term satisfies a modal formula, one can check whether its subterms satisfy formulas that are obtained by decomposing the original formula. The decomposition uses the structural operational semantics that underlies the process algebra. 相似文献
57.
The research literature has seen a number of studies aimed at understanding customer attitudes towards banking technologies, and thereby providing implications for developmental planning and marketing. However, even though banking technologies have a significant amount of information systems (IS) component to them, there is a paucity of research that considers them from the IS perspective. In this paper, we fill this gap by considering three constructs, namely usefulness, ease of use and usage, that are all rooted in the IS literature. We study user’s perceptions of these constructs, as well as the relationships among them, for both online and telephone banking. 相似文献
58.
零售业是生活中常见的行业,在零售业中引入了电子收款机系统(Point of Sells,POS)即进销存管理系统,是商店经营中的最热门的话题之一。这种进销存管理系统一般是现在比较常见的客户端/服务器模式也即C/S模式。文章介绍了采用INSPRISE公司的DELPHI7.0开发工具结合SQL SERVER2000数据库服务器。首先在短时间内建立系统应用原型,然后,对初始原型系统进行需求更迭,不断修正和改进,直到形成用户满意的可行系统。 相似文献
59.
电流变材料及其结构设计 总被引:6,自引:1,他引:5
对各种电流变材料做了较贩综述,并从结构与性能关系的角度进行了简单的分析,以鱼电流变材料的结构设计。 相似文献
60.
黄怀德 《导弹与航天运载技术》1996,(1)
重点介绍有关H—Ⅱ运载火箭(以下简称H—Ⅱ)的一些动力学课题的研究状况。其中,重要的动力学课题有全箭振动、POGO、防液体晃动、分离动力学试验、动力学环境试验等。针对这些动力学课题,日本有关部门已研究多年,既作了充分的地面试验,又进行了有效的工程应用研究,最终保证了H—Ⅱ的首次飞行成功。 相似文献