全文获取类型
收费全文 | 20024篇 |
免费 | 2059篇 |
国内免费 | 1349篇 |
专业分类
电工技术 | 1414篇 |
综合类 | 1756篇 |
化学工业 | 2193篇 |
金属工艺 | 1963篇 |
机械仪表 | 1891篇 |
建筑科学 | 1196篇 |
矿业工程 | 1367篇 |
能源动力 | 730篇 |
轻工业 | 1728篇 |
水利工程 | 608篇 |
石油天然气 | 810篇 |
武器工业 | 215篇 |
无线电 | 1569篇 |
一般工业技术 | 2128篇 |
冶金工业 | 604篇 |
原子能技术 | 211篇 |
自动化技术 | 3049篇 |
出版年
2024年 | 73篇 |
2023年 | 275篇 |
2022年 | 523篇 |
2021年 | 600篇 |
2020年 | 652篇 |
2019年 | 542篇 |
2018年 | 568篇 |
2017年 | 693篇 |
2016年 | 779篇 |
2015年 | 837篇 |
2014年 | 1229篇 |
2013年 | 1303篇 |
2012年 | 1495篇 |
2011年 | 1637篇 |
2010年 | 1235篇 |
2009年 | 1180篇 |
2008年 | 996篇 |
2007年 | 1406篇 |
2006年 | 1221篇 |
2005年 | 933篇 |
2004年 | 806篇 |
2003年 | 706篇 |
2002年 | 594篇 |
2001年 | 500篇 |
2000年 | 448篇 |
1999年 | 406篇 |
1998年 | 274篇 |
1997年 | 282篇 |
1996年 | 244篇 |
1995年 | 181篇 |
1994年 | 168篇 |
1993年 | 126篇 |
1992年 | 107篇 |
1991年 | 71篇 |
1990年 | 74篇 |
1989年 | 57篇 |
1988年 | 42篇 |
1987年 | 24篇 |
1986年 | 26篇 |
1985年 | 20篇 |
1984年 | 22篇 |
1983年 | 19篇 |
1982年 | 20篇 |
1981年 | 6篇 |
1980年 | 9篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
151.
152.
Sand casting process and directional solidification technique combining thermal-rate treatment(TRT) were used. The influence of process parameters on TRT was investigated according to the values of impact toughness. At the same time, the mechanism of TRT was discussed. The results showed that TRT can improve the impact toughness of this alloy, while the hardness is basically constant. The time of heat preservation should not be more than 5min. Different forms of cooling intensification additive have different effects among which the zinc ingot solidified in graphite mold is the best one that can improve impact toughness of samples by more than 80%. With increasing the cooling temperature, the value of α(Al) crystal lattice constant increases. The element Sb has negative effect on TRT. 相似文献
153.
154.
The solubility parameter of poly(ethylene oxide) at 25°C has been determined using the method developed by DiPaola-Baranyi and Guillet, by the extrapolation of the values of the interaction parameter χ, at high temperatures, ranging from 70°–90°, 90°–110° and 110°–130°C down to 25°C. The values of the solubility parameter obtained, depending on the temperature ranges employed, are 9.8, 9.9 and 10.1, respectively. 相似文献
155.
156.
157.
Design of fluidized bed photoreactors: Optical properties of photocatalytic composites of titania CVD-coated onto quartz sand 总被引:1,自引:0,他引:1
Volumetric optical properties (spectral absorption, scattering and extinction coefficients) of differently expanded narrow-path fluidized beds (FB) of a photocatalyst obtained by plasma-CVD deposition of titania onto quartz sand, relevant for photoreactor design purposes, are determined by using an unidirectional and unidimensional (1DD) model for the solution of the radiative transfer equation (RTE). Two simplified approaches are used: a Kubelka-Munk (KM) type of solution, by which the RTE is transformed into a pair of ordinary differential equations, and a discrete ordinate method (DOM) by which the complete RTE is transformed into an algebraic system that can be solved computationally. The second approach was validated by introducing the obtained optical parameters into a more elaborated bi-directional and two-dimensional (2DD) DOM model. Despite its simplicity, the KM method was able to yield fair order-of-magnitude estimates of the spectral optical properties of these FB. 相似文献
158.
Shigezo Naito 《臭氧:科学与工程》2006,28(6):425-429
Ozone has the strongest oxidization effect after fluorine, and this property has been used in sterilization for food and processing plants in Japan. Moreover, there is no fear of toxic residues as with chlorine-based sterilizers and no hazardous trihalomethanes are formed. Based on these advantages, ozone has been used in water and air treatment for food products food materials and food processing plants. Use in the food processing is now increasing in Japan. This paper describes ozone sterilization, introducing sterilization systems and equipment applied to food in Japan. 相似文献
159.
160.
概述了广义线性模型(含半参数广义线性模型)与非线性模型研究的新进展,着重讨论了它们参数估计的统计推断。近年来,广义线性模型与非线性模型的研究发展迅速,有着广泛的应用前景。 相似文献