全文获取类型
收费全文 | 127927篇 |
免费 | 7180篇 |
国内免费 | 3586篇 |
专业分类
电工技术 | 6221篇 |
技术理论 | 10篇 |
综合类 | 11193篇 |
化学工业 | 9325篇 |
金属工艺 | 5278篇 |
机械仪表 | 14146篇 |
建筑科学 | 29377篇 |
矿业工程 | 3966篇 |
能源动力 | 3021篇 |
轻工业 | 5194篇 |
水利工程 | 4022篇 |
石油天然气 | 4089篇 |
武器工业 | 1439篇 |
无线电 | 7710篇 |
一般工业技术 | 13353篇 |
冶金工业 | 3046篇 |
原子能技术 | 662篇 |
自动化技术 | 16641篇 |
出版年
2024年 | 458篇 |
2023年 | 1255篇 |
2022年 | 2097篇 |
2021年 | 2672篇 |
2020年 | 2948篇 |
2019年 | 2265篇 |
2018年 | 2207篇 |
2017年 | 2807篇 |
2016年 | 3229篇 |
2015年 | 3514篇 |
2014年 | 9159篇 |
2013年 | 7195篇 |
2012年 | 8985篇 |
2011年 | 9653篇 |
2010年 | 8196篇 |
2009年 | 8472篇 |
2008年 | 7646篇 |
2007年 | 9154篇 |
2006年 | 7683篇 |
2005年 | 6768篇 |
2004年 | 5432篇 |
2003年 | 5117篇 |
2002年 | 4095篇 |
2001年 | 3430篇 |
2000年 | 2796篇 |
1999年 | 2175篇 |
1998年 | 1792篇 |
1997年 | 1508篇 |
1996年 | 1273篇 |
1995年 | 1007篇 |
1994年 | 812篇 |
1993年 | 567篇 |
1992年 | 447篇 |
1991年 | 382篇 |
1990年 | 239篇 |
1989年 | 244篇 |
1988年 | 186篇 |
1987年 | 143篇 |
1986年 | 86篇 |
1985年 | 95篇 |
1984年 | 128篇 |
1983年 | 81篇 |
1982年 | 94篇 |
1981年 | 32篇 |
1980年 | 38篇 |
1979年 | 28篇 |
1978年 | 13篇 |
1977年 | 12篇 |
1976年 | 9篇 |
1959年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
34.
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
35.
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
36.
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
37.
《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
38.
Daniela D'Amato Maria Rosaria Corbo Matteo Alessandro Del Nobile & Milena Sinigaglia 《International Journal of Food Science & Technology》2006,41(10):1152-1157
In enology, alcoholic fermentation is a complex process involving several mechanisms. Slow and incomplete alcoholic fermentation is a chronic problem for the wine industry and factors leading to sluggish and stuck fermentations have been extensively studied and reviewed. The most studied cause of sluggish and stuck fermentation is the nitrogen content limitation. Nevertheless, other factors, such as temperature of fermentation and sugar concentration can affect the growth of yeasts. In this study we modelled the yeast growth‐cycle in wine model system as a function of temperature, sugar and ammonium concentrations; the individual effects and the interaction of these factors were analysed by means of a quadratic response surface methodology. Cell concentrations and weight loss were monitored in the whole wine fermentation process. The results of central composite design show that lower is the availability of nitrogen, higher is the cell growth rate; moreover, initial nitrogen concentration also influences survival time of Saccharomyces cerevisiae. 相似文献
39.
Menberu Lulu 《Quality Engineering》2003,16(1):105-111
Quality and reliability design practitioners have utilized Taguchi's methodology of matrix experimentation to generate computer simulation data for characterizing performance variation of product designs. However, the sampling strategy employed renders computer implementation of matrix experimentation cumbersome and statistically invalid. Weaknesses of this approach also include sample size limitation and overestimation of performance variation. An alternative approach that combines Monte Carlo simulation with the strategies of independent sampling across runs and correlated sampling between runs is presented. An application case study shows that the proposed approach constitutes an improvement on the matrix approach with respect to statistical validity and estimation accuracy. 相似文献
40.