全文获取类型
收费全文 | 71810篇 |
免费 | 7286篇 |
国内免费 | 4009篇 |
专业分类
电工技术 | 5827篇 |
技术理论 | 3篇 |
综合类 | 6134篇 |
化学工业 | 5487篇 |
金属工艺 | 6795篇 |
机械仪表 | 8138篇 |
建筑科学 | 12244篇 |
矿业工程 | 2833篇 |
能源动力 | 1990篇 |
轻工业 | 3180篇 |
水利工程 | 3368篇 |
石油天然气 | 4305篇 |
武器工业 | 1510篇 |
无线电 | 4437篇 |
一般工业技术 | 6894篇 |
冶金工业 | 2965篇 |
原子能技术 | 658篇 |
自动化技术 | 6337篇 |
出版年
2024年 | 345篇 |
2023年 | 1023篇 |
2022年 | 1891篇 |
2021年 | 2241篇 |
2020年 | 2577篇 |
2019年 | 2044篇 |
2018年 | 2013篇 |
2017年 | 2700篇 |
2016年 | 2813篇 |
2015年 | 2903篇 |
2014年 | 4390篇 |
2013年 | 4086篇 |
2012年 | 5251篇 |
2011年 | 5469篇 |
2010年 | 4163篇 |
2009年 | 4211篇 |
2008年 | 3747篇 |
2007年 | 4692篇 |
2006年 | 4360篇 |
2005年 | 3671篇 |
2004年 | 3132篇 |
2003年 | 2554篇 |
2002年 | 2203篇 |
2001年 | 1894篇 |
2000年 | 1529篇 |
1999年 | 1253篇 |
1998年 | 1045篇 |
1997年 | 864篇 |
1996年 | 824篇 |
1995年 | 688篇 |
1994年 | 500篇 |
1993年 | 347篇 |
1992年 | 322篇 |
1991年 | 205篇 |
1990年 | 193篇 |
1989年 | 155篇 |
1988年 | 109篇 |
1987年 | 70篇 |
1986年 | 48篇 |
1985年 | 37篇 |
1984年 | 35篇 |
1981年 | 22篇 |
1980年 | 65篇 |
1979年 | 47篇 |
1965年 | 26篇 |
1964年 | 34篇 |
1960年 | 23篇 |
1959年 | 32篇 |
1956年 | 29篇 |
1955年 | 32篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
以灌溉、防洪为主的峡口水库大坝,为沥青混凝土面板堆石坝,为研究低温抗裂性能,对沥青混凝土面板破损取样,进行了配比和多种力学性能试验,并与原面板设计指标进行了对比。由于面板经受住了-20℃以下的低温考验,其所用沥青指标、破损取样试验结果,特别是冻断低温指标,对确定水工沥青混凝土低温抗裂检验标准有重要参考价值。 相似文献
53.
One of the new physical methods that provides much information about the processes going on in a friction contact zone in real time is acoustic emission (AE). Basic experimental results of AE in friction are presented and analysed. Using AE signals we can get an indication about the state of the friction processes, about the quality of solid and liquid layers on the contacting surfaces in real time, sometimes about intensity of wear, changing of wear and friction regimes and so on. The influence of sliding velocity, load, roughness and some physical and mechanical properties of the body on the parameters of AE are also given. Some attention to the practical implementation of these techniques for control of capability for work of friction pairs in real conditions are given. Modern methods and devices enable condition monitoring of sliding and rolling bearings. 相似文献
54.
文章探讨了GB 12437-2000标准规定的产品检验项目中,中包浸水试验的科学性问题和对批产品进行抽样时的样本代表性问题以及使用多段爆速仪测试爆速时应注意的样本量问题. 相似文献
55.
棉织物手感值的模糊综合评判研究 总被引:4,自引:0,他引:4
利用模糊综合评判数学模型对棉织物的手感值进行了计算与分析,这种方法简单、可靠,与主观评估结果有很好的一致性,为纺织生产的质量判断提供了便利。 相似文献
56.
L. M. CRUZ-ORIVE 《Journal of microscopy》2005,219(1):18-28
A new principle is presented to generate isotropic uniform random (IUR) test lines hitting a geometric structure in three-dimensional space (3D). The principle therefore concerns the estimation of surface area, volume, membrane thickness, etc., of arbitrary structures with piecewise smooth boundary. The principle states that a point-sampled test line on an isotropic plane through a fixed point in 3D is effectively an invariant test line in 3D. Particular attention is devoted to the stereology of particles, where an alternative to the surfactor method is obtained to estimate surface area. An interesting case arises when the particle is convex. The methods are illustrated with synthetic examples. 相似文献
57.
58.
Gomatofu (sesame tofu) is one of the traditional Japanese healthy foods and is representative of all shojin (vegetarian) dishes. Gomatofu, one of the mixed gels consisting of kudzu (arrowroot) starch and sesame, possesses an extremely unusual textural characteristic which is soft, smooth, and springy. The textural properties are greatly influenced by preparation, ingredients and roasting conditions of sesame seeds. Hence there are many kinds of sesame materials which can be used to prepare gomatofu such as white, black, huskless or not and roasted or unroasted sesame materials, in this study, the effects of these materials on the physical properties of gomatofu were studied. The sample of Ra-W prepared with unroasted huskless sesame seed had the least hardness, but mouthfeel of this sample were the highest. The samples of Ro-B and Ro-W prepared with roasted husk (black and white) sesame seed were evaluated to have the best palatability because of their superior springiness. It was clarified that different kinds of sesame materials affected the forming of structure and physical properties of gomatofu, because the chemical components were different from varieties of sesame materials. 相似文献
59.
60.
Thin hard coatings fracture propagation during the impact test 总被引:2,自引:0,他引:2
One of the most significant applications of the impact test is to investigate thin hard coatings fatigue properties. Herein the test conditions and duration up to the film damage initiation, are considered in order to determine the critical stresses associated with the coating fatigue strength. Moreover, the subsequent film damage propagation is a significant mechanism as well, since it refers to the ability of the coating to withstand loads after its fatigue damage initiation. In order to describe the film fracture propagation the failed area ratio was introduced and an algorithm to determine this magnitude developed, based on the analysis of imprint scanning electron microscopy graphs. The application of the coating failed area ratio will be demonstrated in various impact test film cases, also with superficial thin layers. The top layers do not affect, in general, the failure initiation of the basic coating. However, according to the obtained results, the superficial films influence the basic coating failure propagation rate during the impact test. 相似文献