全文获取类型
收费全文 | 141693篇 |
免费 | 9867篇 |
国内免费 | 5639篇 |
专业分类
电工技术 | 10249篇 |
技术理论 | 7篇 |
综合类 | 12577篇 |
化学工业 | 9435篇 |
金属工艺 | 5374篇 |
机械仪表 | 14919篇 |
建筑科学 | 29039篇 |
矿业工程 | 4096篇 |
能源动力 | 3501篇 |
轻工业 | 5224篇 |
水利工程 | 3960篇 |
石油天然气 | 4200篇 |
武器工业 | 1581篇 |
无线电 | 10101篇 |
一般工业技术 | 13867篇 |
冶金工业 | 3162篇 |
原子能技术 | 712篇 |
自动化技术 | 25195篇 |
出版年
2024年 | 618篇 |
2023年 | 1598篇 |
2022年 | 2664篇 |
2021年 | 3347篇 |
2020年 | 3676篇 |
2019年 | 2892篇 |
2018年 | 2755篇 |
2017年 | 3509篇 |
2016年 | 3952篇 |
2015年 | 4343篇 |
2014年 | 10234篇 |
2013年 | 8189篇 |
2012年 | 10082篇 |
2011年 | 10642篇 |
2010年 | 9043篇 |
2009年 | 9348篇 |
2008年 | 8516篇 |
2007年 | 10125篇 |
2006年 | 8391篇 |
2005年 | 7549篇 |
2004年 | 6135篇 |
2003年 | 5677篇 |
2002年 | 4534篇 |
2001年 | 3782篇 |
2000年 | 3068篇 |
1999年 | 2414篇 |
1998年 | 1966篇 |
1997年 | 1644篇 |
1996年 | 1393篇 |
1995年 | 1118篇 |
1994年 | 901篇 |
1993年 | 622篇 |
1992年 | 488篇 |
1991年 | 405篇 |
1990年 | 257篇 |
1989年 | 253篇 |
1988年 | 201篇 |
1987年 | 146篇 |
1986年 | 94篇 |
1985年 | 104篇 |
1984年 | 128篇 |
1983年 | 87篇 |
1982年 | 97篇 |
1981年 | 35篇 |
1980年 | 43篇 |
1979年 | 32篇 |
1978年 | 17篇 |
1977年 | 13篇 |
1959年 | 12篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Ken Smith 《Color research and application》2007,32(4):249-255
This study describes a process of relating the perceptual analysis of the colors of the terrestrial atmosphere to currently available pigments used in artists' painting systems. This process sought to discover how the colors of the sky could be defined and simulated by these pigments. The author also describes how confusion over the bewildering choice of suitable pigments on offer in the market place can be clarified. © 2006 Wiley Periodicals, Inc. Col Res Appl, 32, 249–255, 2007 相似文献
32.
Design for a high power-density Astron reactor 总被引:1,自引:0,他引:1
N. C. Christofilos 《Journal of Fusion Energy》1989,8(1-2):97-105
A liquid lithium blanket surrounding the plasma volume is described. The liquid lithium flows along magnetic flux tubes at a high speed. There is no vacuum wall between the blanket and the plasma. The E-layer of relativistic particles within which the plasma is confined serves as a vacuum wall protecting the plasma from the lithium vapor, which is continuously produced at the surface of the blanket, by ionizing the lithium atoms and ejecting the same along open magnetic lines. The heat load at the surface of the blanket generated by 14 MeV neutrons can be several hundred MW per square meter.Work performed under the auspices of the U.S. Atomic Energy Commission.Deceased September 24, 1972. 相似文献
33.
Combined shape and sizing optimization of truss structures 总被引:1,自引:0,他引:1
In this paper, an evolutionary optimization method is presented for weight minimum problem of a 3-dimensional truss structure
in terms of nodal coordinates and element cross-sectional areas. The structure is subject to stress, local buckling and displacement
constraints. Two types of design variables with different natures are optimized separately: (1) a fully stressed design (FSD)
and scaling techniques are applied to sizing variables and (2) the evolutionary node shift method is applied to shape variables.
Alternating procedure is utilized to couple the two types of variables and to combine the results. The optimum solution is
achieved gradually from the initial configuration design. Two typical truss structures are examined to illustrate the validity
of the method.
Received: 22 October 2001 / Accepted: 04 June 2002
This research work is supported by the National Natural Science Foundation of China under the guarantees no. 10072050 and
10172072, respectively. 相似文献
34.
35.
36.
37.
The aim of this study was to evaluate the effects of paste properties on residence time during drying in a spouted bed dryer with inert bodies. The effect of paste solids content, surface tension, and viscosity on the residence time distribution and the mean residence times were studied using factorial experimental designs. The inert bodies used were glass and polyethylene beads. The mean residence times varied from 13.6 to 16.3 and 12.2 to 17.7 min for drying on glass and polyethylene beads, respectively. The analysis of variance showed that mean residence times significantly depended on solids content and surface tension for glass beads and also on viscosity for polyethylene beads. The residence time distributions for all conditions studied fitted well to the perfect mixing cell when applying the continuous stirred vessels in series model analysis. The powder density, flowability, and particle size depended on paste properties and inert type. 相似文献
38.
M. Portillo
J. H. Dohr
《Design Studies》1994,15(4):403-416Scholars in design face two central challenges in design methods inquiry: firstly, to integrate process and solution, and secondly, to examine developmental junctures leading to innovation. With these goals in mind, we maintain that design criteria deserve greater attention and illustrate this position with a study of noted designers' use of criteria. The primary finding was that five criteria functions were considered during the design process. The study also explored potential relationships between designer variables (i.e., professional expertise and personality type) and criteria use. 相似文献
39.
This paper presents observations regarding the cracking behavior of tensile-loaded structural adhesive joints. Experiments showed that fracture occurred by the development and propagation of a damage zone, rather than a single, sharp crack, and that the presence of the adhesive spew fillet did not affect the fracture load of the adhesive joints studied. For joints bonded with the mineral-filled epoxy Cybond 4523GB (American Cyanamid), there was approximately 5 mm of subcritical crack propagation prior to final fracture. Fracture-load predictions based on the initial uncracked geometry made in previous papers were unaffected by this small change in geometry. For joints bonded with the rubber-toughened epoxy Permabond ESP 310, approximately 50 mm of subcritical crack propagation was observed. It was again found that predictions made in previous papers on the basis of the initial geometry gave a good estimate of the final fracture load even though this subcritical crack propagation significantly altered the geometry, and thus the applied energy release rates. The effect of shear deformations of the adherends was also investigated, and it was found that shear deformations could be neglected in engineering calculations for joints subject to remote tensile loading. 相似文献
40.
《燃气红外线辐射供暖系统设计选用及施工安装》国家标准图集介绍 总被引:1,自引:0,他引:1
介绍了该国家标准图集的主要内容:设计说明、典型设计、工程实例、系统设备、燃气管道安装、液化石油气气化站、电气控制及温度检测、施工安装说明。 相似文献