全文获取类型
收费全文 | 174275篇 |
免费 | 21004篇 |
国内免费 | 18622篇 |
专业分类
电工技术 | 13616篇 |
技术理论 | 71篇 |
综合类 | 22300篇 |
化学工业 | 17061篇 |
金属工艺 | 5195篇 |
机械仪表 | 11907篇 |
建筑科学 | 27582篇 |
矿业工程 | 6164篇 |
能源动力 | 7216篇 |
轻工业 | 5051篇 |
水利工程 | 10348篇 |
石油天然气 | 8189篇 |
武器工业 | 2668篇 |
无线电 | 12739篇 |
一般工业技术 | 15833篇 |
冶金工业 | 5629篇 |
原子能技术 | 1441篇 |
自动化技术 | 40891篇 |
出版年
2024年 | 920篇 |
2023年 | 2787篇 |
2022年 | 4922篇 |
2021年 | 5844篇 |
2020年 | 6236篇 |
2019年 | 5267篇 |
2018年 | 5033篇 |
2017年 | 6222篇 |
2016年 | 7215篇 |
2015年 | 7539篇 |
2014年 | 11858篇 |
2013年 | 11208篇 |
2012年 | 12674篇 |
2011年 | 13632篇 |
2010年 | 10925篇 |
2009年 | 11293篇 |
2008年 | 11305篇 |
2007年 | 12961篇 |
2006年 | 11329篇 |
2005年 | 9998篇 |
2004年 | 8243篇 |
2003年 | 6944篇 |
2002年 | 5380篇 |
2001年 | 4364篇 |
2000年 | 3766篇 |
1999年 | 2898篇 |
1998年 | 2351篇 |
1997年 | 1950篇 |
1996年 | 1786篇 |
1995年 | 1545篇 |
1994年 | 1249篇 |
1993年 | 908篇 |
1992年 | 757篇 |
1991年 | 557篇 |
1990年 | 444篇 |
1989年 | 372篇 |
1988年 | 241篇 |
1987年 | 156篇 |
1986年 | 116篇 |
1985年 | 120篇 |
1984年 | 133篇 |
1983年 | 66篇 |
1982年 | 80篇 |
1981年 | 45篇 |
1980年 | 62篇 |
1979年 | 53篇 |
1978年 | 18篇 |
1974年 | 10篇 |
1959年 | 17篇 |
1951年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
A cell vertex finite volume method for the solution of steady compressible turbulent flow problems on unstructured hybrid
meshes of tetrahedra, prisms, pyramids and hexahedra is described. These hybrid meshes are constructed by firstly discretising
the computational domain using tetrahedral elements and then by merging certain tetrahedra. A one equation turbulence model
is employed and the solution of the steady flow equations is obtained by explicit relaxation. The solution process is accelerated
by the addition of a multigrid method, in which the coarse meshes are generated by agglomeration, and by parallelisation.
The approach is shown to be effective for the simulation of a number of 3D flows of current practical interest.
Sponsored by The Research Council of Norway, project number 125676/410
Dedicated to the memory of Prof. Mike Crisfield, a respected colleague 相似文献
12.
电信企业信息化的实质就是赋予电信企业精细化的企业资源整合能力,本以此认识为出发点,通过定义基本的信息化业务元素,需求参数和基本信息处理机制,构建出带有行业共性的电信企业信息化统一模型,该模型针对目前电信企业信息化中常见的和潜在的问题提供了有效的解决措施。 相似文献
13.
地理空间信息网格调度技术,要比传统的高性能计算中的调度技术复杂,原因是如果将全部网格资源作为一个应用程序的调度和执行目标,必将导致通信延迟、成本昂贵、执行低效等。为此,综合考虑应用程序特性、机器特性等,研究设计了地理空间信息网格高性能调度技术中的应用程序调度模型,包括地理空间信息网格应用程序分析;资源特性分析;应用程序分解;性能预测;资源调度;机器选择;任务映射;任务调度;任务调度器和调度器管理模块。以实现为不同的应用程序匹配不同的计算资源,提高计算资源的利用率和应用程序的执行效率。 相似文献
14.
The present work deals with the modelling of damage behaviour for sheet moulding compound (SMC) composite materials using a finite element analysis package. Specifically, a comparison is made between the results obtained experimentally for a three-point bending test, and those obtained from numerical simulation using a material model already implemented. The simulation has been performed for the material models available within the PAM-CRASH software. The simulation results are compared and validated with respect to experimentation. 相似文献
15.
为了提高非稳定渗流计算的计算精度 ,通过数学分析得到了水位传导系数随时间变化时 ,一类非稳定渗流井流模型的半解析解 ,并进行了计算比较 相似文献
16.
17.
18.
From its foundation until 2004, ETRI has registered over 1,000 US patents. This letter analyzes the characteristics of these patents and addresses the explanatory factors affecting their citation counts. For explanatory variables, research team related variables, invention specific variables, and geographical domain related variables are suggested. Zero‐altered count data models are used to test the impact of independent variables. A key finding is that technological cumulativeness, the scale of invention, outputs in the electronic field, and the degree of dependence on the US technology domain positively affect the citation counts of ETRI‐invented US patents. The magnitude of international presence appears to negatively affect the citation counts of ETRI‐invented US patents. 相似文献
19.
The Intellectual Development of Science and Engineering Students. Part 2: Teaching to Promote Growth
As college students experience the challenges of their classes and extracurricular activities, they undergo a developmental progression in which they gradually relinquish their belief in the certainty of knowledge and the omniscience of authorities and take increasing responsibility for their own learning. At the highest developmental level normally seen in college students (which few attain before graduation), they display attitudes and thinking patterns resembling those of expert scientists and engineers, including habitually and skillfully gathering and analyzing evidence to support their judgments. This paper proposes an instructional model designed to provide a suitable balance of challenge and support to advance students to that level. The model components are (1) variety and choice of learning tasks; (2) explicit communication and explanation of expectations; (3) modeling, practice, and constructive feedback on high‐level tasks; (4) a student‐centered instructional environment; and (5) respect for students at all levels of development. 相似文献
20.