全文获取类型
收费全文 | 1713篇 |
免费 | 32篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 117篇 |
综合类 | 2篇 |
化学工业 | 495篇 |
金属工艺 | 50篇 |
机械仪表 | 36篇 |
建筑科学 | 23篇 |
能源动力 | 110篇 |
轻工业 | 131篇 |
水利工程 | 10篇 |
石油天然气 | 1篇 |
无线电 | 134篇 |
一般工业技术 | 306篇 |
冶金工业 | 114篇 |
原子能技术 | 54篇 |
自动化技术 | 165篇 |
出版年
2023年 | 8篇 |
2022年 | 19篇 |
2021年 | 25篇 |
2020年 | 17篇 |
2019年 | 26篇 |
2018年 | 16篇 |
2017年 | 18篇 |
2016年 | 33篇 |
2015年 | 22篇 |
2014年 | 49篇 |
2013年 | 118篇 |
2012年 | 93篇 |
2011年 | 96篇 |
2010年 | 76篇 |
2009年 | 102篇 |
2008年 | 96篇 |
2007年 | 67篇 |
2006年 | 64篇 |
2005年 | 65篇 |
2004年 | 48篇 |
2003年 | 54篇 |
2002年 | 46篇 |
2001年 | 32篇 |
2000年 | 36篇 |
1999年 | 44篇 |
1998年 | 63篇 |
1997年 | 34篇 |
1996年 | 42篇 |
1995年 | 22篇 |
1994年 | 23篇 |
1993年 | 28篇 |
1992年 | 26篇 |
1991年 | 17篇 |
1990年 | 14篇 |
1989年 | 22篇 |
1988年 | 18篇 |
1987年 | 9篇 |
1986年 | 13篇 |
1985年 | 16篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 9篇 |
1981年 | 15篇 |
1980年 | 18篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1977年 | 10篇 |
1976年 | 10篇 |
1975年 | 5篇 |
1968年 | 4篇 |
排序方式: 共有1748条查询结果,搜索用时 31 毫秒
121.
The dynamics of magnetic reversal process plays an important role in the design of the magnetic recording devices in the long time scale limit. In addition to long time scale, microscopic effects such as the entropic effect become important in magnetic nano-scale systems. Many advanced simulation methods have been developed, but few have the ability to simulate the long time scale limit and to accurately model the microscopic effects of nano-scale systems at the same time. We develop a new Monte Carlo method for calculating the dynamics of magnetic reversal at arbitrary long time. For example, actual calculations were performed up to 1050 Monte Carlo steps. This method is based on microscopic interactions of many constituents and the master equation for magnetic probability distribution function is solved symbolically. 相似文献
122.
Hiroshi Kihira Takehide Senuma Kiyoshi Nishioka Yutaka Sakata 《Corrosion Science》2005,47(10):2377-2390
Japanese Specification for Highway Bridges [Japan Road Association: Specification for Highway Bridges—I & II, 2002.3] has been revised in 2002, which clearly states that degradation of bridge members, including those of weathering steels, to occur in prolonged period of time must be taken into account at the design stage to realize long term structural durability. To cope with the revised paradigm, SABI chemistry committee in Japan Society of Corrosion Engineers has proposed durable state concept [SABI Chemistry Committee of Japan Society of Corrosion Engineers, in: Proc. 132nd Symposium for Corrosion and Protection, 2001.6.25, p. 3], which is defined as a condition in which corrosion rate of steel is slow enough not to form thick rust [H. Kihira, K. Shiotani, H. Miyuki, T. Nakayama, M. Takemura, Y. Watanabe, Doboku Gakkai Ronbun-shu (J. Japan Soc. Civil Engineers) No. 745/I-65, 2003.10, pp.77-87]. Since corrosiveness of atmosphere differs by location, a corrosion prediction method for both conventional and advanced weathering steels [H. Kihira, A. Usami, K. Tanabe, M. Ito, G. Shigesato, Y. Tomita, T. Kusunoki, T. Tsuzuki, S. Ito, T. Murata, in: Electrochemical Society Proceedings, vol. 99-26, 2000, pp. 127-136] is needed to ensure structural durability for future. Thus, versatile computational scheme for it has been derived through mathematical modeling based upon the durable state concept. 相似文献
123.
124.
Yutaka Tokuda Youichi Nagae Hitoshi Sakane Jyoji Ito 《Journal of Electronic Materials》2010,39(6):719-722
Defect production behavior in hydrogen-implanted n-type silicon has been studied by varying the implantation temperature from 88 K to 303 K. Deep-level transient spectroscopy
has been used to reveal electron trap spectra for Schottky diodes fabricated at room temperature after implantation. Metastable
defects are observed in addition to vacancy- and hydrogen-related defects. It is found that the production rates of these
defects are greatly enhanced by hydrogen implantation near 270 K. It is suggested that hydrogen plays an important role in
enhancement of defect production rates, since such defect production behavior is not observed in He-implanted samples. 相似文献
125.
126.
Numata M Nakamura N Koshikawa H Terashima Y 《Environmental science & technology》2002,36(20):4389-4394
Chlorine isotope fractionation during reductive dechlorination of trichloroethene (TCE) and tetrachloroethene (PCE) to cis-1,2-dichloroethene (cDCE) by anaerobic bacteria was investigated. The changes in the 37Cl/35Cl ratio observed during the one-step reaction (TCE to cDCE) can be explained by the regioselective elimination of chlorine accompanied by the Rayleigh fractionation. The fractionation factors (alpha) of the TCE dechlorination by three kinds of anaerobic cultures were approximately 0.994-0.995 at 30 degrees C. The enrichment of 37Cl in the organic chlorine during the two-step reaction (PCE to cDCE) can be explained by the random elimination of one chlorine atom in the PCE molecule followed by the regioselective elimination of one chlorine atom in the TCE molecule. The fractionation factors for the first step of the PCE dechlorination with three kinds of anaerobic cultures were estimated to be 0.987-0.991 at 30 degrees C using a mathematical model. Isotope fractionation during the first step would be the primary factor for the chlorine isotope fractionation during the PCE dechorination to cDCE. The developed models can be utilized to evaluate the fractionation factors of regioselective and multistep reactions. 相似文献
127.
Takeda K Ishiguro Y Tanaka R Maruyama J Kasamatsu T Okawa S Hori S 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2002,43(5):280-288
Ion-trap GC/MS/MS was evaluated for the multi-residue determination of pesticides in agricultural products. Matrices were extracted from samples (spinach, carrot, onion and brown rice) with acetone and submitted to gel permeation chromatography, followed by a clean-up step through a graphite carbon cartridge. Thirty-five pesticides were added to either matrix, and analyzed by GC/MS/MS. Detection limits of pesticides by GC/MS/MS was almost the same as those by GC/MS (SIM). Coefficients of variation of peak area in 5 measurements of each pesticide at 0.1 microgram/mL or 0.05 microgram/mL with or without matrices were mostly acceptable, though those of 20 pesticides out of 35 were higher than 10% at a concentration of 0.02 microgram/mL. It was indicated that matrix artifacts, which interfere with GC/MS-Scan analysis, could be eliminated in some cases by using GC/MS/MS. 相似文献
128.
Tomohiro Itoh Kenji Ohguchi Chizuru Nakajima Masayoshi Oyama Munekazu Iinuma Yoshinori Nozawa Yukihiro Akao Masafumi Ito 《Food chemistry》2011
We found that two distinct flavonoid glycosides isolated from the peel of Japanese persimmon (Diospyros kaki Fuyu), isoquercitrin (Isq) and hyperin (Hyp), are capable of inhibiting antigen-stimulated degranulation in rat basophilic leukaemia RBL-2H3 cells. In order to elucidate the underlying mechanisms, we examined effects of Isq and Hyp on cellular responses induced by antigen stimulation. Treatment with both Isq and Hyp markedly inhibited antigen-stimulated elevation of intracellular free Ca2+ concentration and reactive oxygen species (ROS). Isq and Hyp did not affect NADPH oxidase (NOX) activity, but they possessed DPPH radical-scavenging activity similar to that of epigallocatechin gallate, a potent anti-oxidant, Finally, Isq and Hyp showed little or no effects on Ag-stimulated Syk activation or phosphorylation of signalling molecules. These results indicate that inhibition of antigen-stimulated degranulation by Isq and Hyp is mainly due to suppression of intracellular Ca2+ elevation, which is caused by direct scavenging of ROS that are generated by NOX. Our findings suggest that Isq and Hyp, isolated from the peel of persimmon, would be beneficial for alleviating symptoms of type I allergy. 相似文献
129.
The 2005 Fukuoka-ken Seiho-oki earthquake caused damage to structures due to liquefaction, slope failure and strong shaking in Fukuoka City. One of the authors had conducted microzonation for liquefaction, slope failure and strong shaking about 17 years before the earthquake. After the earthquake, the authors compared the zoning map with the actual damage. The results showed that liquefied sites coincided fairly well with predicted zones in the reclaimed lands. However, they were slightly different in a big sand spit named Uminonakamichi. Failure occurred at several slopes inside the predicted areas, while damage to buildings occurred due to strong shaking along the Kego Fault. The damaged area was slightly different from the predicted area. Furthermore, a liquefaction analysis was conducted and the results of this analysis were compared with the results of microzonation in 1988. In this paper, the authors discuss the validity of microzonation based on this comparison. 相似文献
130.
Takayuki Ban Naoya Nakashima Tomohiko Nakatani Yutaka Ohya 《Journal of the American Ceramic Society》2009,92(6):1230-1235
We hydrothermally synthesized anatase films on Ti substrates from transparent aqueous solutions of layered titanate colloids. The morphology and wetting properties of the films were examined. The films consisted of columnar aggregates grown on the Ti substrates, which resulted in high orientation. Randomly oriented films were obtained when alumina was used as a substrate, whereas the sol–gel precoating of a titanium oxide (TiO2 ) layer on alumina substrates resulted in similar orientation as that of the films on Ti substrates. Thus, the presence of TiO2 on the substrate surface plays an important role in the orientation of columnar aggregates. The columnar aggregates were similar in microstructure to the arms of a type of six-pointed star-like anatase aggregate synthesized hydrothermally from the same reaction solutions. They were composed of twins of tapered anatase nanocrystals, which provided a rough film surface. The film surface was highly hydrophilic and oleophilic due to the nanoscale roughness even when the film was not irradiated with UV light. 相似文献