全文获取类型
收费全文 | 816篇 |
免费 | 32篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 74篇 |
综合类 | 4篇 |
化学工业 | 264篇 |
金属工艺 | 9篇 |
机械仪表 | 10篇 |
建筑科学 | 23篇 |
能源动力 | 36篇 |
轻工业 | 89篇 |
水利工程 | 3篇 |
石油天然气 | 6篇 |
无线电 | 53篇 |
一般工业技术 | 159篇 |
冶金工业 | 16篇 |
原子能技术 | 16篇 |
自动化技术 | 89篇 |
出版年
2023年 | 4篇 |
2022年 | 13篇 |
2021年 | 15篇 |
2020年 | 8篇 |
2019年 | 9篇 |
2018年 | 11篇 |
2017年 | 19篇 |
2016年 | 16篇 |
2015年 | 11篇 |
2014年 | 13篇 |
2013年 | 41篇 |
2012年 | 45篇 |
2011年 | 39篇 |
2010年 | 49篇 |
2009年 | 44篇 |
2008年 | 44篇 |
2007年 | 39篇 |
2006年 | 31篇 |
2005年 | 34篇 |
2004年 | 36篇 |
2003年 | 28篇 |
2002年 | 24篇 |
2001年 | 23篇 |
2000年 | 14篇 |
1999年 | 13篇 |
1998年 | 20篇 |
1997年 | 20篇 |
1996年 | 11篇 |
1995年 | 9篇 |
1994年 | 14篇 |
1993年 | 8篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 9篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 12篇 |
1985年 | 15篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有851条查询结果,搜索用时 0 毫秒
121.
Yasuhiro Yamada Hajime Yasuda Kazumasa Murota Masashi Nakamura Toshiaki Sodesawa Satoshi Sato 《Journal of Materials Science》2013,48(23):8171-8198
X-ray photoelectron spectroscopy (XPS) is among the most powerful methods to determine the surface chemical properties of carbon materials. Because heat-treated graphite oxide includes various defects, analyses of the structure by XPS help us understand the structures of various carbon materials. Thus, XPS spectra of graphene-related materials containing various functional groups and other defects on edges and in the basal plane were simulated and full width at half maximums (FWHMs) and peak shifts were obtained by density functional theory calculation. Shifts of whole C1s spectra were influenced by the electron-withdrawing functional groups such as C=O-containing functional groups. FWHMs of the main peak of C1s spectra were influenced by mainly electron-withdrawing functional groups in addition to defects such as vacancy, pentagons, and heptagons. Analyses using only XPS provide us limited information, even though the peak tops and FHWMs of simulated XPS spectra are used for assignment. Combination use of peak shifts and FWHMs of XPS spectra, infrared spectroscopy, and density functional theory calculation provided more reliable assignments of defects including oxygen-containing functional groups of carbon materials than commonly used methods using only peak shifts of XPS spectra. 相似文献
122.
123.
Shinya Inai Yuji Hiruma Muneyasu Suzuki Hajime Nagata Tadashi Takenaka 《Ceramics International》2008,34(4):741-744
The temperature dependence of the piezoelectric properties of vanadium substituted strontium bismuth niobate, SrBi2Nb1.95V0.05O9 (SBNV) ceramics, were investigated in various vibration modes. The effects of grain orientation in SBNV ceramics on the piezoelectric properties were also studied by the hot-forging (HF) method. The anisotropy of the piezoelectric properties of each vibration mode was confirmed by observing the grain orientation. In particular, HF-SBNV ceramics of the (33) and (15) modes showed excellent piezoelectric properties with relatively high mechanical quality factors, Qm (2200, 4600), and high electrical quality factors, Qe max (66.0, 21.6), respectively. In addition, HF-SBNV ceramics showed low temperature coefficients of resonance frequency TC-fr (−16.5, −27.0). HF-SBNV ceramics are considered to be superior candidates for the lead-free piezoelectric application of ceramic resonators. 相似文献
124.
Ogawa M Tohma Y Ohgushi H Takakura Y Tanaka Y 《International journal of molecular sciences》2012,13(5):5528-5541
To establish the methods of demonstrating early fixation of metal implants to bone, one side of a Cobalt-Chromium (CoCr) based alloy implant surface was seeded with rabbit marrow mesenchymal cells and the other side was left unseeded. The mesenchymal cells were further cultured in the presence of ascorbic acid, β-glycerophosphate and dexamethasone, resulting in the appearance of osteoblasts and bone matrix on the implant surface. Thus, we succeeded in generating tissue-engineered bone on one side of the CoCr implant. The CoCr implants were then implanted in rabbit bone defects. Three weeks after the implantation, evaluations of mechanical test, undecalcified histological section and electron microscope analysis were performed. Histological and electron microscope images of the tissue engineered surface exhibited abundant new bone formation. However, newly formed bone tissue was difficult to detect on the side without cell seeding. In the mechanical test, the mean values of pull-out forces were 77.15 N and 44.94 N for the tissue-engineered and non-cell-seeded surfaces, respectively. These findings indicate early bone fixation of the tissue-engineered CoCr surface just three weeks after implantation. 相似文献
125.
126.
Spatial confinement is known to induce a drastic change in the viscosity, relaxation times, and flow profile of liquids near the glass (or jamming) transition point. The essential underlying question is how a wall affects the dynamics of densely packed systems. Here we study this fundamental problem, using experiments on a driven granular hard-sphere liquid and numerical simulations of polydisperse and bidisperse colloidal liquids. The nearly hard-core nature of the particle-wall interaction provides an ideal opportunity to study purely geometrical confinement effects. We reveal that the slower dynamics near a wall is induced by wall-induced enhancement of 'glassy structural order', which is a manifestation of strong interparticle correlations. By generalizing the structure-dynamics relation for bulk systems, we find a quantitative relation between the structural relaxation time at a certain distance from a wall and the correlation length of glassy structural order there. Our finding suggests that glassy structural ordering may be the origin of the slow glassy dynamics of a supercooled liquid. 相似文献
127.
Shogo Ishizuka Akimasa Yamada Paul J. Fons Hajime Shibata Shigeru Niki 《Progress in Photovoltaics: Research and Applications》2014,22(7):821-829
Simultaneous realization of high values of open circuit voltage (Voc), fill factor (FF), and energy conversion efficiency (η) in wide‐gap CuGaSe2 (CGS) solar cells has long been one of the most challenging issues in the realm of chalcopyrite photovoltaics. In this communication, structural tuning of CGS thin films by means of controlling the amount of Se flux used during CGS film growth and improvements in solar cell performance (Voc > 0.9 V, FF > 0.7, and η > 10%) are demonstrated. Systematic variations in CGS film properties with the Se flux and correlation with device properties are shown. The unique CGS thin‐film growth kinetics, which are different from narrow‐gap Cu(In,Ga)Se2, are also presented and discussed. This development of double digit efficiency for CGS solar cells opens a new frontier for the broad application of a new class of chalcopyrite‐based devices. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
128.
Hiromichi Maeno Kazato Oishi Tadayoshi Mitsuhashi Hajime Kumagai Hiroyuki Hirooka 《Meat science》2014
The objective of this study was to develop equations to predict carcass tissue weights and percentages and boneless carcass non-trimmed cut weights by using the cold carcass weight (CCW) and three other traits at the 6–7th rib section, which are routinely collected in carcass markets in Japan. Carcasses from 94 Japanese Black steers were used for the multiple regression analysis with a stepwise procedure and a novel Least Absolute Shrinkage and Selection Operator (LASSO). The accuracies of prediction (R2) and RMSEs for the carcass tissue and cut weights were similar between the two procedures. In contrast, LASSO appeared to be the better procedure for predicting carcass tissue percentages. The longissimus muscle area and subcutaneous fat thickness were the important predictors for the lean percentage in the stepwise procedure, and CCW was additionally selected when the LASSO procedure was used. 相似文献
129.
We study external quantum efficiency (ηEQE) roll-off in organic light-emitting diodes (OLEDs) using thermally-activated delayed fluorescence (TADF) of 4,5-di (9H-carbazol-9-yl) phthalonitrile (2CzPN). Using 2CzPN intramolecular rate constants from optical analyses, we construct an exciton quenching model incorporating intersystem crossing and reverse intersystem crossing. The model indicates that singlet–triplet annihilation and triplet–triplet annihilation dominate ηEQE roll-off because of the relatively long 2CzPN triplet lifetime of 273 μs. This work yields a method to relax the exciton quenching process in TADF based OLEDs. 相似文献
130.
Choa An Takahiro Yazaki Hajime Takahashi Takashi Kuda Bon Kimura 《Journal of Functional Foods》2013,5(1):389-394
Brown algae contain soluble polysaccharides, such as alginic acid, fucoidan and laminaran. To assess the induction of dietary fiber-fermenting bacteria in the intestine, rats were fed diet containing no dietary fiber (control) or 2% w/w of the polysaccharides for 2 weeks. The levels of dietary fiber-fermenting bacteria in caecal contents were determined using decimal dilution culture containing 1% w/v of the fibers. Caecal microbiota in the rats was analyzed using polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). In the culture method, 4–9 log viable cells/g caecal content of alginate-fermenting bacteria was detected in rats fed alginate, while this was not detected in rats fed the control diet. Although laminaran-fermenting bacteria were detected in control rats (4–9 log viable cells/g), the level observed in rats fed laminaran was 8 or 9 log viable cells/g. On the other hand, fucoidan-fermenting bacteria were not detected in rats fed fucoidan. DGGE analysis showed laminaran administration increased the diversity of bacterial bands. Clostridium spp. and Parabacteroides distasonis were detected as typical species in rats fed alginate and laminaran. The results indicate that the intake of soluble fermentable fibers in edible brown algae can alter the intestinal microbiota and its fermentation capacity. 相似文献