全文获取类型
收费全文 | 1020篇 |
免费 | 16篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 94篇 |
综合类 | 4篇 |
化学工业 | 289篇 |
金属工艺 | 20篇 |
机械仪表 | 21篇 |
建筑科学 | 51篇 |
能源动力 | 34篇 |
轻工业 | 90篇 |
水利工程 | 10篇 |
无线电 | 111篇 |
一般工业技术 | 138篇 |
冶金工业 | 70篇 |
原子能技术 | 46篇 |
自动化技术 | 61篇 |
出版年
2022年 | 12篇 |
2021年 | 19篇 |
2020年 | 9篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 11篇 |
2016年 | 20篇 |
2015年 | 7篇 |
2014年 | 13篇 |
2013年 | 43篇 |
2012年 | 31篇 |
2011年 | 31篇 |
2010年 | 34篇 |
2009年 | 38篇 |
2008年 | 50篇 |
2007年 | 35篇 |
2006年 | 39篇 |
2005年 | 39篇 |
2004年 | 31篇 |
2003年 | 25篇 |
2002年 | 48篇 |
2001年 | 9篇 |
2000年 | 20篇 |
1999年 | 25篇 |
1998年 | 37篇 |
1997年 | 42篇 |
1996年 | 28篇 |
1995年 | 29篇 |
1994年 | 32篇 |
1993年 | 23篇 |
1992年 | 13篇 |
1991年 | 15篇 |
1990年 | 15篇 |
1989年 | 14篇 |
1988年 | 14篇 |
1987年 | 20篇 |
1986年 | 19篇 |
1985年 | 14篇 |
1984年 | 17篇 |
1983年 | 14篇 |
1982年 | 14篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1979年 | 12篇 |
1978年 | 10篇 |
1977年 | 4篇 |
1976年 | 9篇 |
1975年 | 7篇 |
1973年 | 9篇 |
1972年 | 3篇 |
排序方式: 共有1039条查询结果,搜索用时 15 毫秒
1.
2.
The cover image is based on the Mini‐Review Well‐defined, environment‐friendly synthesis of polypeptides based on phosgene‐free transformation of amino acids into urethane derivatives and their applications by Takeshi Endo et al., https://doi.org/10.1002/pi.5952 . Cover image © Takeshi Endo Images.
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.
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
5.
6.
K Sudo Y Matsumoto M Matsushima M Fujiwara K Konno K Shimotohno S Shigeta T Yokota 《Canadian Metallurgical Quarterly》1997,238(2):643-647
This study evaluated the inhibitory effects of thiazolidine derivatives on hepatitis C virus (HCV) protease and other human serine proteases. The inhibition efficacy was tested with a reversed-phase high-performance liquid chromatography (HPLC) assay system using a NS3-NS4A fusion protein as the HCV protease and a synthetic peptide substrate that mimics the NS5A-5B junction. Nine thiazolidine derivatives showed more than 50% inhibition at 50 microg/ml. The most potent derivative was RD4-6250, with 50% inhibition at a concentration of 2.3 microg/ml; this concentration was lower than those of other protease inhibitors reported previously. The most selective derivative was RD4-6205, with 50% inhibition at a concentration of 6.4 microg/ml, a lower concentration than those on other serine proteases (chymotrypsin, trypsin, plasmin, and elastase). These results suggest that the RD4-6205 skeleton is an important structure for inhibitory activity on the HCV protease NS3-NS4A. 相似文献
7.
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
8.
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
9.
In this paper, we study the existence of cycles of all lengths in the recursive circulant graphs, and we show a necessary and sufficient condition for the graph being pancyclic and bipancyclic. 相似文献
10.
Yukio Sato Tomohito Tanaka Fumiyasu Oba Takahisa Yamamoto Yuichi Ikuhara Taketo Sakuma 《Science and Technology of Advanced Materials》2003,4(6):137
SrTiO3 and ZnO bicrystals with various types of boundaries were fabricated in order to examine their current–voltage characteristics across single grain boundaries. Their grain boundary structures were also investigated by high-resolution transmission electron microscopy. In Nb-doped SrTiO3, electron transport behaviors depend on the type of boundaries. Random type boundaries exhibit highly non-linear current–voltage characteristics, while low angle boundaries show a slight non-linearity. On the contrary, undoped ZnO does not exhibit non-linear current–voltage characteristics in any type of boundaries including random ones. It is suggested that the differences observed in current–voltage properties between the two systems are mainly due to the difference in the accumulation behavior of acceptor-like native defects at grain boundaries. A clear non-linearity is obtained by means of Co-doping even for the highly coherent Σ1 boundary in a ZnO bicrystal. This is considered to result from the production of acceptor-like native defects by Co-doping. 相似文献