全文获取类型
收费全文 | 585篇 |
免费 | 16篇 |
专业分类
电工技术 | 45篇 |
化学工业 | 164篇 |
金属工艺 | 7篇 |
机械仪表 | 6篇 |
建筑科学 | 10篇 |
能源动力 | 25篇 |
轻工业 | 55篇 |
水利工程 | 4篇 |
无线电 | 32篇 |
一般工业技术 | 127篇 |
冶金工业 | 49篇 |
原子能技术 | 8篇 |
自动化技术 | 69篇 |
出版年
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 12篇 |
2015年 | 6篇 |
2014年 | 12篇 |
2013年 | 23篇 |
2012年 | 26篇 |
2011年 | 31篇 |
2010年 | 21篇 |
2009年 | 32篇 |
2008年 | 30篇 |
2007年 | 16篇 |
2006年 | 24篇 |
2005年 | 27篇 |
2004年 | 19篇 |
2003年 | 23篇 |
2002年 | 22篇 |
2001年 | 14篇 |
2000年 | 18篇 |
1999年 | 16篇 |
1998年 | 28篇 |
1997年 | 19篇 |
1996年 | 18篇 |
1995年 | 16篇 |
1994年 | 7篇 |
1993年 | 11篇 |
1992年 | 3篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 8篇 |
1987年 | 9篇 |
1986年 | 4篇 |
1985年 | 9篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有601条查询结果,搜索用时 31 毫秒
41.
对电解二氧化锰(EMD)的粉末与大颗粒中和工艺进行了考察。电子微探分析(EPMA)结果表明:大颗粒中和的EMD粒子内部及粒子之间,存在Na含量的偏差。粉末中和EMD的Na含量,较大颗粒中和的EMD低30%~50%。大颗粒中和与粉末中和相比,需要较强的中和条件。 相似文献
42.
43.
44.
Mizutani A Kikuta H Iwata K Toyota H 《Journal of the Optical Society of America. A, Optics, image science, and vision》2002,19(7):1346-1351
We describe a new structure of guided-mode resonant grating (GMRG) filters with low sideband reflectance. This GMRG filter consists of a high-index thin film on an antireflective structured surface called "moth-eye structure." Since the high-index film undulates along the surface structure, the film acts as a modulated optical waveguide. An incident light wave satisfying a resonant condition is reflected by the GMRG filter, and nonresonant light waves pass through the filter. This GMRG filter is valid for reducing reflection of nonresonant light waves in a wide spectral range. The resonant reflection of this new filter was investigated by numerical calculation based on an electromagnetic grating analysis. In the case of a triangular antireflective surface structure whose thickness is 2x greater than its period, the sideband reflectance for nonresonant light waves was lower than 0.5% for TM-polarized light in a wide range of wavelengths. 相似文献
45.
Surface structures of synthetic diamonds 总被引:2,自引:0,他引:2
Hisao Kanda Minoru Akaishi Nobuo Setaka Sinobu Yamaoka Osamu Fukunaga 《Journal of Materials Science》1980,15(11):2743-2748
Diamond crystals of about 2 mm in size were grown by the temperature gradient method using Ni, Ni-Fe alloy and Fe as solvent metals. Several characteristic patterns were seen on the surfaces of the grown diamonds and were found to correspond to the texture of the quenched solvent metals. A vague vein-like pattern appeared when Ni was used. The surface patterns became finer with the increase of the content of Fe in Ni-Fe alloy, and when 70 wt% Fe-30 wt% Ni alloy was used, very fine dendritic patterns were seen on all of the faces of diamond in accordance with the symmetries of the lattice. The patterns are formed by the precipitation of carbon atoms in the space of the dendrites of the solvent metals during the quenching process. Lamellar patterns and etch pits were seen when Fe was used. The patterns are formed when Fe dissolves the diamond surfaces to produce Fe3C during the quenching process. 相似文献
46.
Thermal and nonthermal effects originating when a system is subjected to a microwave radiation field in the TiO2-photocatalyzed transformation of model substances containing various functional groups (e.g., benzoic acid, phthalic acid, o-formylbenzoic acid, phthalaldehyde, succinic acid, dimethyl phthalate, diethyl phthalate, and phenol) have been examined under simultaneous irradiation by ultraviolet (UV) and microwave (MW) radiations. Characteristics of the microwave effects and the fate of each substrate during the microwave-assisted photocatalytic process were monitored by UV absorption spectroscopy, HPLC methods, total organic carbon assays, and identification of intermediates using electrospray mass spectral techniques. Microwave thermal and nonthermal effects were delineated by comparing results from MW-generated internal heat versus conventional external heating, and at constant ambient temperature under a microwave field. Factors involved in the nonthermal component of the microwave radiation were inferred for the initial adsorption of the substrate and its subsequent degradation occurring on the surface of TiO2 particles. Microwave effects bear on the mechanism through which a model substrate undergoes oxidative degradation. A characteristic feature of these effects was briefly examined by considering the behavior of polar (dipole moments) substrates in a microwave radiation field. 相似文献
47.
Tajima T Takiguchi N Kato J Ikeda T Kuroda A Ohtake H 《Journal of Bioscience and Bioengineering》2003,96(2):149-153
The nematode Caenorhabditis elegans exhibits chemotaxis toward a wide variety of chemicals including water-soluble molecules and volatile organic compounds. We have previously discovered that C. elegans wild-type strain N2 is strongly attracted by cycloheximide which has long been known as a bitter tastant for humans and other mammals. We describe here the isolation and initial characterization of the first mutants which were defective specifically in their attraction to cycloheximide. In our screenings, we selected two mutants that were defective in chemotaxis to cycloheximide but normal in their attraction to NH4Cl and histidine. These mutants also avoided quinine hydrochloride, CuSO4 and high concentrations of NaCl similar to the wild-type strain N2. Furthermore, no observable defect was detected in their attraction to volatile odorants such as isoamyl alcohol and diacetyl. Dye-filling experiments suggested that they have no morphological defect in the sensory endings of the amphid neurons. 相似文献
48.
Takeba K Fujinuma K Sakamoto M Jimbo K Oka H Ito Y Nakazawa H 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2003,44(5):246-252
A simple and rapid liquid chromatographic method was developed for the simultaneous determination of twelve benzimidazole anthelmintics in livestock foods using reversed-phase high-performance liquid chromatography with photodiode array detection (PDA). A sample was homogenized with acetonitrile and n-hexane, and centrifuged. The acetonitrile phase was isolated and evaporated. The residue was dissolved in 0.1 mol/L carbonate buffer solution (pH = 9.1), sonicated, and then subjected to clean-up on a Bond Elut LRC-C18 cartridge. The benzimidazole compounds were separated isocratically on a Capcell Pak C18 UG 120 (5 microns, 150 x 4.6 mm i.d.) column and detected by PDA at 295 and 313 nm. Mixtures of acetonitrile and 0.05 mol/L ammonium acetate in mixing ratios of (20:80) and (40:60) were used as the mobile phase, and the flow-rate was 1.0 mL/min at 40 degrees C. The mean recoveries (n = 3) from 0.1-0.5 microgram/g added samples were 72.6-97.2% with coefficients of variation of 0.3-8.5%. The detection limits were 0.01-0.05 microgram/g. 相似文献
49.
Oikawa D Nakanishi T Nakamura Y Takahashi Y Yamamoto T Shiba N Tobisa M Takagi T Iwamoto H Tachibana T Furuse M 《Lipids》2003,38(6):609-614
This study investigated the influence of PUFA on the properties of mouse skin. Mice (3 wk old) were given free access to oils
high in linoleic acid, CLA, or DHA for 4 wk. At the end of the experiment, their skins were compared by both biochemical and
histological methods. No significant differences in lipid and collagen contents were detected among treatments, although the
FA composition in the skin was altered depending upon the FA composition of the supplemented oils. Electron microscopy revealed
that the subcutaneous tissue layers in the CLA and DHA groups were significantly thinner than that in the high linoleic acid
group, whereas no differences in the thickness of dermis layers were observed among the three groups. These results suggest
that skin properties in mice are readily modified by dietary FA sources within 4 wk of dietary oil supplementation. 相似文献
50.
Iida Takahiko Iwamoto Hideo Oka Hisao Funakawa Shigeru 《Industry Applications, IEEE Transactions on》1980,(1):111-118
Fast- switching reverse-conducting thyristors have been developed and used in dc chopper apparatus to control the speed of highvoltage dc traction motors. The newly developed dc chopper circuit and its application for low-voltage dc motor control are discussed. The fast-switching reverse-conducting thyristor is utilized as the main thyristor to control load current. 相似文献