全文获取类型
收费全文 | 827736篇 |
免费 | 12655篇 |
国内免费 | 2550篇 |
专业分类
电工技术 | 15095篇 |
综合类 | 1008篇 |
化学工业 | 124537篇 |
金属工艺 | 30169篇 |
机械仪表 | 23495篇 |
建筑科学 | 21598篇 |
矿业工程 | 3030篇 |
能源动力 | 22542篇 |
轻工业 | 77155篇 |
水利工程 | 7482篇 |
石油天然气 | 10814篇 |
武器工业 | 57篇 |
无线电 | 98050篇 |
一般工业技术 | 155831篇 |
冶金工业 | 163203篇 |
原子能技术 | 14334篇 |
自动化技术 | 74541篇 |
出版年
2021年 | 7086篇 |
2020年 | 5176篇 |
2019年 | 6415篇 |
2018年 | 10837篇 |
2017年 | 10592篇 |
2016年 | 11289篇 |
2015年 | 8353篇 |
2014年 | 13442篇 |
2013年 | 38937篇 |
2012年 | 21808篇 |
2011年 | 30269篇 |
2010年 | 23815篇 |
2009年 | 26659篇 |
2008年 | 27805篇 |
2007年 | 27653篇 |
2006年 | 24413篇 |
2005年 | 22370篇 |
2004年 | 21457篇 |
2003年 | 21111篇 |
2002年 | 20183篇 |
2001年 | 20097篇 |
2000年 | 18684篇 |
1999年 | 19954篇 |
1998年 | 50358篇 |
1997年 | 35708篇 |
1996年 | 27557篇 |
1995年 | 20991篇 |
1994年 | 18403篇 |
1993年 | 17967篇 |
1992年 | 12934篇 |
1991年 | 12331篇 |
1990年 | 11869篇 |
1989年 | 11524篇 |
1988年 | 10862篇 |
1987年 | 9460篇 |
1986年 | 9299篇 |
1985年 | 10906篇 |
1984年 | 10187篇 |
1983年 | 8953篇 |
1982年 | 8367篇 |
1981年 | 8467篇 |
1980年 | 8024篇 |
1979年 | 7803篇 |
1978年 | 7392篇 |
1977年 | 9003篇 |
1976年 | 12230篇 |
1975年 | 6334篇 |
1974年 | 6038篇 |
1973年 | 6039篇 |
1972年 | 4894篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
132.
The dynamic interaction between the mechanical and electrical drive parameters when damage suddenly appears in the mechanical part of a conveyer belt is investigated. The possibility of using the change in the motor’s electrical parameters as a diagnostic signal is assessed. A model for investigating the dynamic processes in the system consisting of the grid, the induction motor, and the conveyer belt is proposed. The grid and induction motor are described by a model of fourth-order state space, whose output is the torque at the motor shaft. The moments of inertia and pliability of the links between the elements in the mechanical part of the conveyer belt are determined. By gradually identifying the elements with the minimum moment of inertia and distributing their moments of inertia and pliabilities among the adjacent elements, we obtain a three-mass system simulating the mechanical part of the conveyer belt. This dynamic model is solved by means of Matlab Simulink software. The energy characteristics of the drive are determined in dynamic processes following a mechanical accident. 相似文献
133.
Karolina M. Wójciak Dariusz M. Stasiak Joanna Stadnik Karolina Ferysiuk Anna Kononiuk 《International Journal of Food Science & Technology》2019,54(1):75-83
In this study, the influence of sonication time on the biogenic amines formation as a critical point in uncured dry-fermented beef manufacturing was studied. Samples of musculus semimembranosus were sonicated at different times (5 and 10 min) using ultrasound cold bath (4 °C) in acid whey (US 40 kHz and acoustic power 480 W). The effect of sonication on biogenic amine (BA) formation was investigated during 93 days of ripening period. Other parameters (pH value, water activity, microbial counts) that might provide further information on the product under study were also determined. The use of ultrasound during beef marinating in acid whey has a positive effect on retarding histamine (HIS), cadaverine (CAD), tyramine (TYR) and putrescine (PUT) formation. Moreover, the sonication treatment did not inhibit the growth of lactic acid bacteria (LAB) in dry-fermented beef during the whole ripening period. The pathogen bacteria (Staphylococcus aureus, Clostridium sp., Listeria monocytogenes) were not detected in all samples neither after 31 nor after 93 days of ripening period. 相似文献
134.
Jialong Tian M. Babar Shahzad Wei Wang Lichang Yin Zhouhua Jiang Ke Yang 《材料科学技术学报》2018,34(9):1671-1675
The effect of Co addition on the formation of Ni-Ti clusters in maraging stainless steel was studied by three dimensional atom probe (3DAP) and first-principles calculation. The cluster analysis based on the maximum separation approach showed an increase in size but a decrease in density of Ni-Ti clusters with increasing the Co content. The first-principles calculation indicated weaker Co-Ni (Co-Ti) interactions than Co-Ti (Fe-Ti) interactions, which should be the essential reason for the change of distribution characteristics of Ni-Ti clusters in bcc Fe caused by Co addition. 相似文献
135.
136.
137.
138.
Senthilkumar M. Vasundhara M. G. Kalavathi G. K. 《International Journal of Mechanics and Materials in Design》2019,15(3):611-627
International Journal of Mechanics and Materials in Design - The resonant frequency of electromechanical energy harvester should be tuned to ambient frequency so as to maximize the harvester power.... 相似文献
139.
Radiochemistry - Azathioprine, an antitumor agent, was labeled with 99mTc using stannous chloride dihydrate as a reducing agent. Factors such as the amounts of the reducing agent and substrate, pH,... 相似文献
140.