全文获取类型
收费全文 | 364524篇 |
免费 | 29083篇 |
国内免费 | 19215篇 |
专业分类
电工技术 | 28338篇 |
技术理论 | 52篇 |
综合类 | 43931篇 |
化学工业 | 50404篇 |
金属工艺 | 19463篇 |
机械仪表 | 19646篇 |
建筑科学 | 45789篇 |
矿业工程 | 17510篇 |
能源动力 | 12729篇 |
轻工业 | 21056篇 |
水利工程 | 14691篇 |
石油天然气 | 13922篇 |
武器工业 | 3573篇 |
无线电 | 24082篇 |
一般工业技术 | 36731篇 |
冶金工业 | 20259篇 |
原子能技术 | 3640篇 |
自动化技术 | 37006篇 |
出版年
2024年 | 1323篇 |
2023年 | 3850篇 |
2022年 | 7187篇 |
2021年 | 8675篇 |
2020年 | 9233篇 |
2019年 | 7752篇 |
2018年 | 7352篇 |
2017年 | 9252篇 |
2016年 | 10430篇 |
2015年 | 11290篇 |
2014年 | 19968篇 |
2013年 | 18681篇 |
2012年 | 24302篇 |
2011年 | 25984篇 |
2010年 | 20363篇 |
2009年 | 21211篇 |
2008年 | 19429篇 |
2007年 | 25791篇 |
2006年 | 24359篇 |
2005年 | 21187篇 |
2004年 | 18076篇 |
2003年 | 16371篇 |
2002年 | 13582篇 |
2001年 | 11618篇 |
2000年 | 9760篇 |
1999年 | 7988篇 |
1998年 | 6147篇 |
1997年 | 5287篇 |
1996年 | 4765篇 |
1995年 | 4037篇 |
1994年 | 3504篇 |
1993年 | 2690篇 |
1992年 | 2286篇 |
1991年 | 1683篇 |
1990年 | 1407篇 |
1989年 | 1222篇 |
1988年 | 963篇 |
1987年 | 672篇 |
1986年 | 474篇 |
1985年 | 406篇 |
1984年 | 404篇 |
1983年 | 311篇 |
1982年 | 275篇 |
1981年 | 185篇 |
1980年 | 157篇 |
1979年 | 124篇 |
1978年 | 67篇 |
1977年 | 74篇 |
1976年 | 59篇 |
1975年 | 60篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
The purpose of this study was to analyze the symbolization of colors as cultural codes, based on costume colors. In order to study the significance of colors in cultural changes, we carried out a quantitative analysis and interpreted it from the perspective of cultural semiotics. The range of this study was focused on Korean costume colors, over diverse diachronic stages of Korean culture. For this study 1535 color samples were collected, measured with a spectrophotometer, and analyzed quantitatively according their diachronic stages of origin. As a result, red, blue, and yellow were found to be the most frequently used colors during the Chosun Dynasty, a period based on Confucianism. These colors acted as cultural codes with cultural significance. During the Modern times pink, light blue, and black increased in frequency and represented the reception of western culture, the changing sex role of women in society, and utilitarianism. In these days, neutral colors and grayish tones of all colors are the most significant colors of high frequency. The use of such colors is closely related to industrialization, mechanization, functionalism, and the changes of women's sex roles in the societies. They are used as cultural codes, especially to emphasize a rational and masculine image rather than a feminine image. © 2006 Wiley Periodicals, Inc. Col Res Appl, 32, 71–79, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20290 相似文献
112.
113.
介绍了造成铁路油槽车底油收不尽的原因,一是节约意识差;二是设备设施陈旧或维护不够;三是操作不当。提出了增强节约意识,挖掘设备潜力,采用合理的吸油方法的对策。 相似文献
114.
O. V. Konstantinova A. V. Kuz’mov V. V. Skorokhod M. B. Shtern 《Powder Metallurgy and Metal Ceramics》2007,46(1-2):25-31
A theoretical method for determining the percolation limit and effective conductivity of composites based on polydisperse
mixtures of insulator and conductor powders is proposed. The effect of the particle size ratio between the insulator and conductor
on the percolation limit and effective conductivity is studied. Numerical simulation of the microstructure, effective properties,
and percolation limit in composites is discussed.
__________
Translated from Poroshkovaya Metallurgiya, Vol. 46, No. 1–2(453), pp. 31–40, 2007. 相似文献
115.
B. E. Rytsar 《Cybernetics and Systems Analysis》2007,43(2):192-207
The paper considers the set-theoretical approach to the joint decomposition of systems of Boolean functions of variables specified
in different representation forms. The approach is based on the method of q-partitions of conjuncterms and concept of decomposition
clones. Theorems on joint decomposition of a system of full and partial functions are formulated. The approach is illustrated
by examples.
Parts I and II of this article are published in No. 5 (2001) and No. 1 (2002).
__________
Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 39–58, March–April 2007. 相似文献
116.
紫杉醇的全合成困难,许多工作还只能停留在实验室的模型化合物上。作者以思想实验方法提出了:先以D-A反应形成A环和C环,然后用两步形成B环,最后形成D环,以此完成紫杉醇母核的全合成。 相似文献
117.
118.
The iron rhenate was compounded by chemical method, which may be generated during wear process of Fe-Re alloys at elevated
temperature. The friction coefficient of iron rhenate has been determined by a pin-on-disc device. The results show that iron
rhenate plays role of lubricating at RT-600 °C. The lubricating behavior is related to the matching pairs. The hardness of
the materials of matching pairs, compatibility of iron rhenate with materials of matching pairs and surface roughness of disc
affect the lubricating behavior of iron rhenate mostly. The principle of matching pairs is proposed.
Project supported by the National Natural Science Foundation of China
Synopsis of the first author Xiong Dangsheng. associated professor, born in 1960. Current research fields include high-temperature self-lubricating alloys
and tribological properties of material. 相似文献
119.
房地产开发企业会计核算问题探讨 总被引:1,自引:0,他引:1
本文就房地产开发企业会计核算的现状及特点进行了分析,并提出了完善房地产开发企业会计核算规范的对策。 相似文献
120.
DS2000-M1是高性能、开放式的LED控制系统,本文从软硬件两方面简述其设计原理。 相似文献