全文获取类型
收费全文 | 95182篇 |
免费 | 1231篇 |
国内免费 | 713篇 |
专业分类
电工技术 | 1643篇 |
综合类 | 65篇 |
化学工业 | 15485篇 |
金属工艺 | 3927篇 |
机械仪表 | 3001篇 |
建筑科学 | 2546篇 |
矿业工程 | 589篇 |
能源动力 | 2383篇 |
轻工业 | 7721篇 |
水利工程 | 1098篇 |
石油天然气 | 2504篇 |
武器工业 | 42篇 |
无线电 | 8595篇 |
一般工业技术 | 19707篇 |
冶金工业 | 16812篇 |
原子能技术 | 2794篇 |
自动化技术 | 8214篇 |
出版年
2022年 | 712篇 |
2021年 | 1139篇 |
2020年 | 890篇 |
2019年 | 1037篇 |
2018年 | 1836篇 |
2017年 | 1855篇 |
2016年 | 2118篇 |
2015年 | 1224篇 |
2014年 | 1995篇 |
2013年 | 4775篇 |
2012年 | 3084篇 |
2011年 | 3735篇 |
2010年 | 3105篇 |
2009年 | 3385篇 |
2008年 | 3481篇 |
2007年 | 3486篇 |
2006年 | 2940篇 |
2005年 | 2631篇 |
2004年 | 2470篇 |
2003年 | 2384篇 |
2002年 | 2272篇 |
2001年 | 2033篇 |
2000年 | 2030篇 |
1999年 | 1911篇 |
1998年 | 4099篇 |
1997年 | 2975篇 |
1996年 | 2304篇 |
1995年 | 1874篇 |
1994年 | 1624篇 |
1993年 | 1695篇 |
1992年 | 1300篇 |
1991年 | 1272篇 |
1990年 | 1342篇 |
1989年 | 1327篇 |
1988年 | 1198篇 |
1987年 | 1123篇 |
1986年 | 1154篇 |
1985年 | 1229篇 |
1984年 | 1070篇 |
1983年 | 1046篇 |
1982年 | 900篇 |
1981年 | 941篇 |
1980年 | 908篇 |
1979年 | 895篇 |
1978年 | 845篇 |
1977年 | 1002篇 |
1976年 | 1132篇 |
1975年 | 772篇 |
1974年 | 721篇 |
1973年 | 720篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
K. A. Abdikalikov V. K. Zadiraka O. S. Kondratenko S. S. Mel'nikova 《Cybernetics and Systems Analysis》1991,27(3):414-419
A fast algorithm is proposed for estimating the auto- and cross-correlation functions of a large signal. The algorithm is based on the sectioning method by the fast Fourier transform. We determine the optimal length of the portion of data read from external memory into RAM which achieves Tmin—a minimum processing time. An estimate of Tmin is obtained.Translated from Kibernetika, No. 3, pp. 78–81, May–June, 1991. 相似文献
13.
Samples of nine different fruits grown in Oyo State of Nigeria were obtained from different market locations within Ibadan Municipality and analysed for their vitamin C content. Sweet orange was found to contain the highest amount of vitamin C ( edible portion) whilst sweet banana variety II contained the lowest amount ( edible portion). Lime, grapefruit, pawpaw and ‘agbalumo’ were found to contain considerable amounts of vitamin C, having 46·5, 47·0, 43·2 and respectively. Consumption of these fruits would thus meet the nutritional requirement for vitamin C in this part of Nigeria. It is also recommended that sweet orange, agbalumo, grapefruit, lime and pawpaw, found to contain considerable amounts of vitamin C, should be processed either at home or factory level to make them available to the people all year round. 相似文献
14.
15.
In the development of a novel freeze-drying technique in a fluidized bed at atmospheric pressure, a parallel study was undertaken using a conventional vacuum equipment. Two kinetically distinct phases were observed during freeze drying of representative Pood samples:
(1) a period during which the rate of drying was constant and (2) a second period during which the drying rate sufferedcontinual reduction. This paper focused attention on the primary drying period which corresponded with the kinetics of sublimation of pure 相似文献
(1) a period during which the rate of drying was constant and (2) a second period during which the drying rate sufferedcontinual reduction. This paper focused attention on the primary drying period which corresponded with the kinetics of sublimation of pure 相似文献
16.
测定钠中杂质的手动阻塞计的研究 总被引:1,自引:1,他引:0
文章介绍了测定钠中杂质浓度的手动阻塞计的原理、装置和实验结果。为了减少测量误差,我们研究了影响准确测定阻塞温度的因素,并且找到了减少测量误差的办法。在同样的杂质饱和温度下,该阻塞计测得的高、低阻塞温度所对应的杂质浓度差是很接近的。对氧其差值为1.03ppm;对氢为0.0763ppm。 相似文献
17.
Action calculi, which generalise process calculi such as Petri nets, π-calculusand ambient calculus, have been presented
in terms of action graphs. We here offer linear action graphs as a primitive basis for action calculi. This paper presents the category of embeddings of undirected linear
action graphs without nesting, using a novel form of graphical reasoning which simplifies some otherwise complex manipulations
in regular algebra. The results are adapted in a few lines to directed graphs. This work is part of a long-term search for
a uniform behavioural theory for process calculi.
Received October 2000 / Accepted in revised form April 2001 相似文献
18.
I. N. Polandov V. K. Novik O. K. Gulish B. P. Bogomolov V. B. Morozov 《Measurement Techniques》1989,32(9):888-890
Translated from Izmeritel'naya Tekhnika, No. 9, pp. 34–35, September, 1989. 相似文献
19.
20.
Commault C. Dion J.-M. Sename O. Motyeian R. 《Automatic Control, IEEE Transactions on》2002,47(12):2074-2079