全文获取类型
收费全文 | 1457篇 |
免费 | 41篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 88篇 |
综合类 | 6篇 |
化学工业 | 338篇 |
金属工艺 | 61篇 |
机械仪表 | 25篇 |
建筑科学 | 28篇 |
矿业工程 | 1篇 |
能源动力 | 48篇 |
轻工业 | 131篇 |
水利工程 | 6篇 |
石油天然气 | 1篇 |
无线电 | 109篇 |
一般工业技术 | 224篇 |
冶金工业 | 329篇 |
原子能技术 | 18篇 |
自动化技术 | 87篇 |
出版年
2023年 | 8篇 |
2022年 | 21篇 |
2021年 | 39篇 |
2020年 | 27篇 |
2019年 | 26篇 |
2018年 | 17篇 |
2017年 | 14篇 |
2016年 | 27篇 |
2015年 | 20篇 |
2014年 | 32篇 |
2013年 | 58篇 |
2012年 | 60篇 |
2011年 | 67篇 |
2010年 | 40篇 |
2009年 | 67篇 |
2008年 | 67篇 |
2007年 | 50篇 |
2006年 | 45篇 |
2005年 | 40篇 |
2004年 | 33篇 |
2003年 | 37篇 |
2002年 | 36篇 |
2001年 | 28篇 |
2000年 | 31篇 |
1999年 | 41篇 |
1998年 | 135篇 |
1997年 | 82篇 |
1996年 | 43篇 |
1995年 | 26篇 |
1994年 | 27篇 |
1993年 | 37篇 |
1992年 | 17篇 |
1991年 | 15篇 |
1990年 | 14篇 |
1989年 | 8篇 |
1988年 | 14篇 |
1987年 | 11篇 |
1986年 | 16篇 |
1985年 | 13篇 |
1984年 | 16篇 |
1983年 | 6篇 |
1982年 | 16篇 |
1981年 | 8篇 |
1980年 | 10篇 |
1979年 | 9篇 |
1978年 | 6篇 |
1977年 | 12篇 |
1976年 | 11篇 |
1975年 | 6篇 |
1974年 | 6篇 |
排序方式: 共有1500条查询结果,搜索用时 15 毫秒
51.
An optical interference method was used to display the distorted film shape in nominally parallel surface thrust washers. The bearings were made of aluminium to accentuate thermal expansion and were carefully lapped flat before use. Both the experimental results and an analysis of the coupled elasticity, Reynolds and energy equations confirm that these bearings operate by the formation of a slightly converging film over the leading 80 percent (or less) of the pad. Fair agreement was obtained between the analysis and previously developed multiple regression equations. Thrust washers for industrial use with random waviness are likely lo perform better than lapped bearings. 相似文献
52.
53.
54.
Hiromi Yoshida Takaaki Tanigawa Naoko Yoshida Isoko Kuriyama Yuka Tomiyama Yoshiyuki Mizushina 《Food chemistry》2011
Endogenous tocochromanols in extracted lipids from rice brans of the five cultivars were determined by high-performance liquid chromatography, and were investigated in relation to the fatty acid (FA) distribution of triacylglycerols (TAG) and phospholipids (PL). The dominant tocols were α-tocopherol and γ-tocotrienol, followed by α-tocotrienol and with much smaller amounts of γ-tocopherol and δ-tocotrienol. The lipids of these rice brans comprised mainly TAG (80.6–86.0 wt.%), free FA (4.2–9.0 wt.%), and phospholipids (5.5–6.7 wt.%), whilst other components were also detected in minor proportions (0.2–2.1 wt.%). The PL components included phosphatidyl choline (31.8–46.8 wt.%), phosphatidyl ethanolamine (25.0–38.9 wt.%) and phosphatidyl inositol (20.2–23.2 wt.%). Comparison of these different cultivars showed, with a few exceptions, no significant differences (P > 0.05) in FA distribution. FA distribution of TAG among the five cultivars was evident in the rice brans: unsaturated FA were predominantly concentrated at the sn-2 position and saturated FA primarily occupying the sn-1 or sn-3 position. These results suggest that the tocopherol content, lipid component, and FA distribution in rice brans are not dependent on the cultivation areas during the growing season. 相似文献
55.
In a sample of 263 male GO players at 48 levels of expertise and ranging from 18 to 78 years of age, it was found that factors of expertise deductive reasoning (EDR) and expertise working memory (EWM) were independent of factors of fluid reasoning (Gf) and short-term working memory (STWM) that, along with cognitive speed (Gs), have been found to characterize decline of intelligence in adulthood. The main effects of analyses of cross-sectional age differences indicated age-related decline in EDR and EWM as well as in Gf, STWM, and Gs. However, interaction and partialing analyses indicated that decline in EDR and EWM decreased to no decline with increase in level of expertise. The results thus suggest that with increase in factors known to raise the level of expertise—particularly, intensive, well-designed practice there may be no age-related decline in the intelligence that is measured in the abilities of expertise. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
56.
Takeda Y. Sanada M. Morimoto S. Hirasa T. Taniguchi K. 《Industry Applications, IEEE Transactions on》1994,30(1):141-145
The advantages of the conventional cylindrical linear pulse motor (C-LPM), which has a ring permanent magnet between the A- and B-phase stators, are its simple magnet shape and small motor diameter; the disadvantages are the thrust imbalance resulting from the magnetic flux path of the outer poles being longer than that of the inner poles. This thrust imbalance decreases the pull-in thrust and increases the positioning error. In this paper, a new C-LPM with an interior permanent magnet mover which reduces this thrust imbalance is proposed. Steady and dynamic thrust are also examined and a magnetic equivalent circuit is discussed. It is shown that a C-LPM with an interior permanent magnet mover effectively improves the thrust imbalance and the dynamic thrust 相似文献
57.
The deposition of perovskite-type oxides thin films [La0.8Sr0.2MnO3 and La1–xSrxCo1–yFeyO3 (0 x 0.4 and 0 y 1)] was investigated using the electrostatic spray deposition (ESD) technique. Lanthanum nitrate, strontium chloride and manganese nitrate, or cobalt nitrate and iron nitrate were dissolved into a mixture of 33 vol% ethanol and 67 vol% butyl carbitol, which was used as precursor solution. The effect of process parameters, such as deposition temperature, deposition time and concentration of precursor solution, on the surface morphology and microstructure of thin films were examined with scanning electron microscope (SEM). The deposited La0.8Sr0.2MnO3 and La1–xSrxCo1–yFeyO3 thin films were amorphous at the used deposition temperature (573K). Subsequently, the samples were heated at 1173 K for 2 h and were studied using X-ray diffraction (XRD). As the result, the crystal structure of the samples transformed to the desired perovskite phase. The chemical analysis of the thin films was investigated using energy dispersion X-ray (EDX) analysis. The observed chemical compositions of the samples were in a fair agreement with the ones of the starting solutions. 相似文献
58.
T. Isa T. Fukase M. Sasaki M. Koyano N. Taniguchi T. Kimura Y. Isobe H. Negishi 《Journal of Low Temperature Physics》2002,127(1-2):63-79
We have measured electrical resistivity, Hall coefficient, thermoelectric power, and magnetization for charge-density wave (CDW) material 1T-TaS2 single crystals grown by varying the excess sulfur content x
es. We have revealed that a small mid-gap state is formed inside the Mott gap and that anomalous low temperature transport is not governed by the Mott gap state itself but by the mid-gap state. The electric properties of the mid-gap state are modified by increasing x
es (or hole doping), and we have found the insulator-metal transition occurs by hole doping below 60K. 相似文献
59.
Taniguchi Shigeji Zhu Yao-Can Fujita Kazuhisa Iwamoto Nobuya 《Oxidation of Metals》2002,58(3-4):375-390
Coupon specimens of TiAl were implanted with Nb ions at an acceleration voltage of 50 kV with a dose of 1021 ions m.–2 They were then slightly oxidized during heating to 900 or 1200 K, or at 1200 K for 3.6 ksec (1 hr) in a flow of purified oxygen under atmospheric pressure. The implanted specimens and oxidized specimens were characterized and observed by AES, X-ray diffractometry, SEM, TEM, EDS, and EPMA. Implantation improves the oxidation resistance significantly by forming virtually -Al2O3 scales. The implanted layer is about 75 nm thick; the outer part of 30-nm thickness is -Ti phase and the rest of 45-nm thickness is amorphous. Heating to 900 K in O2 results in partial crystallization of the amorphous layer to Ti5Al3O2 (Z-phase) and to 1200 K results in oxide scales of 270 to 400 nm thickness consisting mainly of Al2O3. The fraction of Al2O3 in the scale increases toward the substrate. Oxidation at 1200 K for 3.6 ksec results in Al2O3-rich scales of about 400-nm thickness. The oxide grain size is very fine, about 80 nm in size, and becomes smaller toward the outer scale surface. This implies that implantation enhanced the nucleation of Al2O3 grains relative to the growth of TiO2 grains. This finding and the formation of -Ti phase are thought to be responsible for the excellent oxidation resistance obtained. 相似文献
60.
This paper presents calibration of the Vehicle Routing and scheduling Problems with Time Windows-Probabilistic (VRPTW-P) model
which takes into account the uncertainty of travel times. Probe vehicle data of travel times were obtained from usual operation
of pickup-delivery trucks in South Osaka area. The optimal solution of the VRPTW-P model resulted in reducing total cost,
running times and CO2, NOx and Particle Materials (PM) emissions compared with the usual operation. This is attributed to better routing of VRPTW-P
to choose more reliable roads. Therefore, VRPTW-P can contribute to establish efficient and environmentally friendly delivery
systems in urban area. 相似文献