全文获取类型
收费全文 | 189584篇 |
免费 | 12453篇 |
国内免费 | 5687篇 |
专业分类
电工技术 | 10025篇 |
技术理论 | 11篇 |
综合类 | 13821篇 |
化学工业 | 28201篇 |
金属工艺 | 10516篇 |
机械仪表 | 10562篇 |
建筑科学 | 10506篇 |
矿业工程 | 4284篇 |
能源动力 | 4819篇 |
轻工业 | 14276篇 |
水利工程 | 3653篇 |
石油天然气 | 7682篇 |
武器工业 | 1302篇 |
无线电 | 20768篇 |
一般工业技术 | 22206篇 |
冶金工业 | 10091篇 |
原子能技术 | 3062篇 |
自动化技术 | 31939篇 |
出版年
2025年 | 519篇 |
2024年 | 2366篇 |
2023年 | 2328篇 |
2022年 | 3815篇 |
2021年 | 5295篇 |
2020年 | 4498篇 |
2019年 | 4068篇 |
2018年 | 4065篇 |
2017年 | 4475篇 |
2016年 | 4473篇 |
2015年 | 5859篇 |
2014年 | 7757篇 |
2013年 | 9853篇 |
2012年 | 11535篇 |
2011年 | 14750篇 |
2010年 | 11864篇 |
2009年 | 11669篇 |
2008年 | 11602篇 |
2007年 | 11090篇 |
2006年 | 10345篇 |
2005年 | 8776篇 |
2004年 | 7222篇 |
2003年 | 6549篇 |
2002年 | 7029篇 |
2001年 | 5876篇 |
2000年 | 4153篇 |
1999年 | 3086篇 |
1998年 | 2615篇 |
1997年 | 2065篇 |
1996年 | 1804篇 |
1995年 | 1529篇 |
1994年 | 1257篇 |
1993年 | 974篇 |
1992年 | 817篇 |
1991年 | 705篇 |
1990年 | 672篇 |
1989年 | 626篇 |
1988年 | 555篇 |
1987年 | 497篇 |
1986年 | 441篇 |
1985年 | 445篇 |
1984年 | 458篇 |
1983年 | 391篇 |
1978年 | 424篇 |
1977年 | 404篇 |
1976年 | 439篇 |
1975年 | 381篇 |
1974年 | 431篇 |
1973年 | 413篇 |
1972年 | 383篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
The effect of the temperature conditions of melting and the design features of the glass melting furnaces on the increase in the specific removal of glass melt in processing quenched insulating parts of high-voltage suspension insulators is demonstrated. Designs are proposed for glass melting furnaces and glass melting temperature regimes whose use will increase the economy of manufacturing insulators. 相似文献
82.
83.
The empirical equation, 1/ti = AeEi/RT, which expresses the exponential dependence of the reciprocal of crystallization induction time, ti, has been analyzed and shown to be equivalent to the nucleation rate equations derived earlier in Part III (1). Consequently we have used the ti measurements obtained earlier by Krueger and Yeh to calculate not only the nucleation rate enhancements but also the melting point elevations, the relative crystal thickness changes and molecular coil extension ratios of shear-crystallization polyethylene. It is shown that polyethylene when crystallized between 129 and 131°C at shear rates between 1.56 and 9.70 sec?1 can have melting point increases of 4.2 to 7.2°C and crystal thickness decreases of 20 to 25 percent, when compared to those crystallized at 130°C in the quiescent state. The predicted “coil” extension in the melt just prior to shear-induced crystallization ranges between 21 and 36 percent. The results of these analyses as well as those on nucleation rates of polyethylene oxide are discussed in detail. 相似文献
84.
Chang Yang Chengyin Liu Ning Wu Xiang Wu Yidong Li Zhiying Wang 《Neural computing & applications》2014,25(7-8):1741-1754
Collaboration representation-based classification (CRC) was proposed as an alternative approach to the sparse representation method with similar efficiency. The CRC is essentially a competition scheme for the training samples to compete with each other in representing the test sample, and the training class with the minimum representation residual from the test sample wins the competition in the classification. However, the representation error is usually calculated based on the Euclidean distance between a test sample and the weighted sum of all the same-class samples. This paper exploits alternative methods of calculating the representation error in the CRC methods to reduce the representation residual in a more optimal way, so that the sample classes compete with each other in a closer range to represent the test sample. A large number of face recognition experiments on three face image databases show that the CRC methods with optimized presentation residual achieve better performance than the original CRC, and the maximum improvement in classification accuracy is up to 12 %. 相似文献
85.
A. N. Zolotko Ya. I. Vovchuk V. G. Shevchuk N. I. Poletaev 《Combustion, Explosion, and Shock Waves》2005,41(6):611-621
The ignition and combustion of dust-gas suspensions are considered. It is shown that the ability of these systems to accumulate
heat is determined not only by their kinetic and thermal properties but also by the relation between their reaction surface
and the heat-removal surface (f). Experimental information on flame temperatures, ignition delays, and flame propagation over gas suspensions is processed
using the parameter f, and the postulate on the stimulating role of the developed reaction surface in activating these processes is validated.
It is shown that during overall burning, diffusion combustion of particles occurs only for rather small values of f. The ambiguous effect of the parameter f on the ignition and combustion processes leads to the necessity of optimizing the fuel size distribution and concentration
for the effective operation of the power devices. The role of the macroparameters of two-phase flames of refractory metals
in the synthesis of combustion nanoproducts is analyzed.
__________
Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 6, pp. 3–14, November–December, 2005. 相似文献
86.
Yu. N. Shebeko A. Ya. Korol'chenko V. G. Shamonin S. G. Tsarichenko 《Combustion, Explosion, and Shock Waves》1991,27(2):173-175
Through numerical simulation of flame propagation through a methane- and hydrogen-air mixture, with consideration given to the transfer and chemical reactions, we have investigated the relationship between the kinetics of trimolecular reactions and the baric index of the normal burning velocity. It has been demonstrated that the lower the constants of the trimolecular reaction rates, the higher the magnitude of the baric index. In the case of methane the baric index, although it grows, it nevertheless remains negative, while in the case of hydrogen this index changes sign.Balashikha. Translated from Fizika Goreniya i Vzryva, No. 2, pp. 46–49, March–April, 1991. 相似文献
87.
88.
从节能、降低成本、优化工艺的角度,对无菌空气制备过程中,空气预处理流程的选择、空气净化设备、过滤介质以及设备的遴选进行探讨,以实现工艺和工程设计的优化结合。 相似文献
89.
O. N. Fedyaeva A. A. Vostrikov D. Yu. Dubov S. A. Psarov M. Ya. Sokol 《Solid Fuel Chemistry》2007,41(6):323-330
The product composition of the dynamic conversion of brown coal, which was continuously supplied as a water-coal slurry to a flow reactor at 30 MPa, was studied. The temperature of water and coal particles was increased from room temperature to 400°C (top part of the reactor). The conversion of the organic matter of coal was ~48%, and the products collected at the reactor outlet consisted of solid tar components, substances dissolved and emulsified in water, and volatile substances, whose major constituent was CO2. The composition of solid tar components and oils was determined. 相似文献
90.
Shapiro Ya. Z. Zhuchenko O. V. Gaodu A. N. 《Refractories and Industrial Ceramics》1986,27(3-4):159-164
Conclusions The possibility is shown of obtaining lightweight refractories with an operational temperature of 1750°C and having a wide range of properties. The use of these refractories depends on the particular requirements and the conditions of service.Translated from Ogneupory, No. 3, pp. 24–28, March, 1986. 相似文献