全文获取类型
收费全文 | 1438篇 |
免费 | 33篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 124篇 |
综合类 | 4篇 |
化学工业 | 324篇 |
金属工艺 | 32篇 |
机械仪表 | 30篇 |
建筑科学 | 49篇 |
能源动力 | 50篇 |
轻工业 | 119篇 |
水利工程 | 5篇 |
无线电 | 137篇 |
一般工业技术 | 220篇 |
冶金工业 | 193篇 |
原子能技术 | 80篇 |
自动化技术 | 108篇 |
出版年
2022年 | 14篇 |
2021年 | 19篇 |
2020年 | 11篇 |
2019年 | 7篇 |
2018年 | 11篇 |
2017年 | 16篇 |
2016年 | 16篇 |
2015年 | 16篇 |
2014年 | 19篇 |
2013年 | 57篇 |
2012年 | 40篇 |
2011年 | 52篇 |
2010年 | 51篇 |
2009年 | 76篇 |
2008年 | 70篇 |
2007年 | 48篇 |
2006年 | 48篇 |
2005年 | 45篇 |
2004年 | 36篇 |
2003年 | 30篇 |
2002年 | 48篇 |
2001年 | 18篇 |
2000年 | 23篇 |
1999年 | 38篇 |
1998年 | 92篇 |
1997年 | 76篇 |
1996年 | 41篇 |
1995年 | 46篇 |
1994年 | 57篇 |
1993年 | 43篇 |
1992年 | 17篇 |
1991年 | 21篇 |
1990年 | 15篇 |
1989年 | 19篇 |
1988年 | 17篇 |
1987年 | 23篇 |
1986年 | 23篇 |
1985年 | 14篇 |
1984年 | 22篇 |
1983年 | 23篇 |
1982年 | 17篇 |
1981年 | 15篇 |
1980年 | 10篇 |
1979年 | 13篇 |
1978年 | 8篇 |
1977年 | 10篇 |
1976年 | 14篇 |
1975年 | 8篇 |
1973年 | 7篇 |
1972年 | 4篇 |
排序方式: 共有1475条查询结果,搜索用时 31 毫秒
1.
2.
3.
In recent years, computer technology has made remarkable progress and a computer has become an indispensable tool for both engineers and scientists. In this article, utilization of computers in welding research is briefly summarized. Their use in numerical analysis is particularly discussed and applied to physical phenomena in molten pool, hydrogen diffusion and residual stresses due to welding. A comparison is made between theoretical and experimental results. 相似文献
4.
A temperature sensor using a fiber-optic Fabry-Perot interferometer is described. A pseudo-heterodyne detection scheme is adopted to read the light phase difference in the Fabry-Perot interference output. A higher harmonic components comparison method is used to stabilize the system and to increase detection linearity. This system realizes not only highly sensitive temperature sensing with good linearity and minimal adjusting error, but also application to the sensing of other physical quantities such as vibrations. Additionally, the signal-to-noise ratio and distortion of the detected signal are investigated as functions of fiber end reflectivity. These results will be useful in designing a high performance fiber-optic Fabry-Perot thermometer. 相似文献
5.
Y Miyamoto N Imamoto T Sekimoto T Tachibana T Seki S Tada T Enomoto Y Yoneda 《Canadian Metallurgical Quarterly》1997,272(42):26375-26381
The targeting of karyophilic proteins to nuclear pores is mediated via the formation of a nuclear pore-targeting complex, through the interaction of nuclear localization signal (NLS) with its NLS receptor. Recently, a novel human protein, Qip1, was identified from a yeast two-hybrid system with DNA helicase Q1. This study demonstrates that Qip1 is a novel third class of NLS receptor that efficiently recognizes the NLS of the helicase Q1. Moreover, the data obtained in this study show that the specific interaction between Qip1 and the NLS of the helicase Q1 requires its upstream sequence of the minimal essential NLS. By using purified recombinant proteins alone in the digitonin-permeabilized cell-free transport system, it was demonstrated that the two known human NLS receptors, Rch1 and NPI-1, are able to transport all the tested NLS substrates into the nucleus, while Qip1 most efficiently transports the helicase Q1-NLS substrates, which contain its upstream sequence in so far as we have examined the system. Furthermore, in HeLa cell crude cytosol, it was found that endogenous Rch1 binds to all the tested NLS substrates, while the binding of endogenous NPI-1 is restricted to only some NLSs, despite the fact that NPI-1 itself shows binding activity to a variety of NLSs. These results indicate that at least three structurally and functionally distinct NLS receptors exist in the human single cell population, and suggest that the nuclear import of karyophilic proteins may be controlled in a complex manner at the NLS recognition step by the existence of a variety of NLS receptors with various specificities to each NLS. 相似文献
6.
Masato Miyauchi Atsuko Miyake Yukio Nakanishi Yasuyuki Sagara 《Drying Technology》1995,13(8):1741-1761
An experimental study has been carried out on the characteristics of binary adsorption isotherms of water and volatile flavor for typical materials used in a box of a tobacco product or cigarettes. Ethyl acetate chosen as a model for water-soluble volatile flavor. Binary adsorption isotherms for the tobacco, papers, filters, and activated carbons were measured with a flow-type multi-component adsorption system under the canstant conditions of temperature a t 303 K and vapor pressure of water a t 2.5 kPain the vapor pressure range of ethyl acetate from 0 to 4.2 kPa. A linear equation was applied to express the binary adsorption isotherms for the tobacco, papers and filters, while a Dubinin-Astakhov equation was applied for the activated carbons. The binary adsorption was characterized into three groups, depending on the selectivity as well as the mechanism of adsorption; i.e.(l) for tobacco and papers, water was adsorbed much greater rather than ethyl acetate, (2) for filters, ethyl acetate was adsorbed on the surface as great as water, (3) for activated carbons, ethyl acetate was adsorbed much greater onto their micropores rather than water. The results showed that ethyl 相似文献
7.
Few investigations have been made concerning hormonal changes and dyspareunia in fertile aged women with alcoholics experiencing sexual dysfunction. Twenty-seven Japanese woman with alcoholics under 40 years of age excluded with liver cirrhosis were studied to describe alcohol drinking related to sexual dysfunction. Among 21 sexually active women, 20(95.2%) had both symptoms of dyspareunia and vaginal dryness, and only one had neither symptom. Most of patients have lower estradiol levels and 92.0% of patients have the moderately elevated prolactin levels. Eleven of them were having the second grade amenorrhea associated with hyperprolactinemia and hypergonadotropic hypogonadism and 14 were having the first grade amenorrhea. In this study alcoholic abuse women may have deeply related to the hyperprolactinemia, dyspareunia, amenorrhoea, vaginal dryness, ovarian dysfunction and fetal alcohol syndrome. 相似文献
8.
Yukio Tateishi 《Tribology International》1994,27(1)
In this paper improvement in fuel economy by reducing piston ring friction is studied and reduction of piston ring tension and the use of two-ring packages are found to be effective. However, these can be accompanied by adverse effects such as excessive wear and increasing oil consumption, and measures to overcome these problems are studied in detail. 相似文献
9.
Yi Jin Chieko Toeda Takeo Kawaguchi Toshinobu Seki Kazuhiko Juni 《Drug development and industrial pharmacy》1996,22(7):653-658
Permeation of zidovudine (3'-azido-3'-deoxythymidine, AZT) and probenecid from oily bases containing an alcohol through rat skin was examined. Isopropyl myristate (IPM), as an oily vehicle, showed a penetration enhancing effect for AZT and probenecid. Ethanol, n-propanol, and n-butanol were used as additives in IPM and were examined for their own permeation and the enhancing effect on the permeation of AZT and probenecid. The skin permeation of AZT and probenecid from IPM was enhanced by addition of the alcohol in IPM. The degree of the enhancement was decreased with increasing lipophilicity of the alcohol used. me permeation rate of the drug from those systems was shown to be governed by penetration-enhancing effects of the oily base and alcohol, and the penetration of the alcohol itself through the skin. 相似文献
10.
A cryogenic power cable is expected to be capable of carrying bulk power as a main transmission line in a future metropolitan electric power system. It is important to establish a strategy of how to sustain power supply when such a highly densified power supply route trips from the network due to contingency. It is proposed here that the bulk power transmitted by the cryogenic cable could be distributed into the parallel conventional transmission lines by suitable circuit breaker operations in the system. In this process, power-flow routes are forced to be changed with a remarkable modification in the system configuration. In this paper, the power swings associated with the large power-flow change following contingent faults are analyzed by means of a transient network analyzer. It is found that the proposed system modification could be realized without any harmful power swing if the parameters in generators as well as in control devices have conventional magnitudes. It is shown also by simulations that the margin to occurrence in an unstable power swing is left sufficient even if the parameters deviate somewhat from the present magnitudes. 相似文献