全文获取类型
收费全文 | 1196篇 |
免费 | 54篇 |
国内免费 | 19篇 |
专业分类
电工技术 | 63篇 |
综合类 | 1篇 |
化学工业 | 325篇 |
金属工艺 | 40篇 |
机械仪表 | 35篇 |
建筑科学 | 22篇 |
能源动力 | 67篇 |
轻工业 | 102篇 |
水利工程 | 2篇 |
石油天然气 | 2篇 |
无线电 | 93篇 |
一般工业技术 | 230篇 |
冶金工业 | 130篇 |
原子能技术 | 38篇 |
自动化技术 | 119篇 |
出版年
2023年 | 11篇 |
2022年 | 27篇 |
2021年 | 62篇 |
2020年 | 29篇 |
2019年 | 32篇 |
2018年 | 37篇 |
2017年 | 25篇 |
2016年 | 46篇 |
2015年 | 25篇 |
2014年 | 51篇 |
2013年 | 84篇 |
2012年 | 57篇 |
2011年 | 91篇 |
2010年 | 59篇 |
2009年 | 56篇 |
2008年 | 61篇 |
2007年 | 38篇 |
2006年 | 37篇 |
2005年 | 40篇 |
2004年 | 25篇 |
2003年 | 31篇 |
2002年 | 28篇 |
2001年 | 20篇 |
2000年 | 17篇 |
1999年 | 27篇 |
1998年 | 45篇 |
1997年 | 34篇 |
1996年 | 29篇 |
1995年 | 17篇 |
1994年 | 23篇 |
1993年 | 15篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1977年 | 6篇 |
1976年 | 11篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 4篇 |
1970年 | 3篇 |
排序方式: 共有1269条查询结果,搜索用时 31 毫秒
61.
Kotaka A Bando H Kaya M Kato-Murai M Kuroda K Sahara H Hata Y Kondo A Ueda M 《Journal of Bioscience and Bioengineering》2008,105(6):622-627
Three beta-glucosidase- and two endoglucanase-encoding genes were cloned from Aspergillus oryzae, and their gene products were displayed on the cell surface of the sake yeast, Saccharomyces cerevisiae GRI-117-UK. GRI-117-UK/pUDB7 displaying beta-glucosidase AO090009000356 showed the highest activity against various substrates and efficiently produced ethanol from cellobiose. On the other hand, GRI-117-UK/pUDCB displaying endoglucanase AO090010000314 efficiently degraded barley beta-glucan to glucose and smaller cellooligosaccharides. GRI-117-UK/pUDB7CB codisplaying both beta-glucosidase AO090009000356 and endoglucanase AO090010000314 was constructed. When direct ethanol fermentation from 20 g/l barley beta-glucan as a model substrate was performed with the codisplaying strain, the ethanol concentration reached 7.94 g/l after 24 h of fermentation. The conversion ratio of ethanol from beta-glucan was 69.6% of the theoretical ethanol concentration produced from 20 g/l barley beta-glucan. These results showed that sake yeast displaying A. oryzae cellulolytic enzymes can be used to produce ethanol from cellulosic materials. Our constructs have higher ethanol production potential than the laboratory constructs previously reported. 相似文献
62.
Koji Fushimi Takatoshi Shimada Hiroki Habazaki Hidetaka Konno Masahiro Seo 《Electrochimica acta》2011,(4):1773
Depassivation–repassivation of iron surfaces in boric–borate solutions were investigated by using the micro-indentation test. A pair of current peaks due to repair of the passive film following rupture of the film were observed during a series of indenter drives, i.e., loading and unloading of the indenter. The shape of the current peak depended on environmental conditions (conductivity and pH of the solution) and substrate conditions (mechanical processing history, alloyed element) as well as indentation conditions (repetition, maximum depth, and maximum load). Plastic deformation of the surface was accompanied by surface depassivation, while no depassivation occurred during the elastic deformation, indicating that the passive film on iron has a ductile property. The solution conditions did not affect the scale of depassivation but affected the rate of repassivation. Dislocations in the substrate made surface depassivation difficult but enhanced reactivity during the repassivation. The test also revealed that type-312L stainless steel has high corrosion resistance in a concentrated NaCl solution. 相似文献
63.
Kazuto Takashima Rei Shimomura Takayuki Kitou Hiroki Terada Kiyoshi Yoshinaka Ken Ikeuchi 《Tribology International》2007,40(2):319
Therapeutic vascular catheterization techniques are sometimes hampered by the frictional forces between the blood vessel and the catheter, when contact points of the vessel are changing and deforming during the movement of the catheter. The goal of the present study was to characterize frictional interactions between the blood vessel wall and the catheter using experimental and numerical analysis. First, the frictional force was measured with an experimental apparatus that uses a ball and flattened porcine aorta to simulate frictional forces between the catheter and the vessel. Second, catheter motion was characterized by two-dimensional numerical calculations based on the experimental results. Experimental analysis demonstrated that slip occurred and that friction coefficient between the vessel and the catheter and the deformation of the specimen were small when the contact between the ball and the aorta occurred at a small angle. The compliance of the specimen in the normal direction obtained by the experiment was by far larger than that calculated according to the Hertzian contact theory. Numerical analysis shows that this difference of the parameter of the vessel, which must be determined accurately in surgical simulator, could affect the trajectory of the catheter. 相似文献
64.
Hiroki Iwamoto Alexey Stankovskiy Luca Fiorito Gert Van den Eynde 《Journal of Nuclear Science and Technology》2018,55(5):539-547
The applicability of Monte Carlo techniques, namely the Monte Carlo sensitivity method and the random-sampling method, for uncertainty quantification of the effective delayed neutron fraction βeff is investigated using the continuous-energy Monte Carlo transport code, MCNP, from the perspective of statistical convergence issues. This study focuses on the nuclear data as one of the major sources of βeff uncertainty. For validation of the calculated βeff, a critical configuration of the VENUS-F zero-power reactor was used. It is demonstrated that Chiba's modified k-ratio method is superior to Bretscher's prompt k-ratio method in terms of reducing the statistical uncertainty in calculating not only βeff but also its sensitivities and the uncertainty due to nuclear data. From this result and a comparison of uncertainties obtained by the Monte Carlo sensitivity method and the random-sampling method, it is shown that the Monte Carlo sensitivity method using Chiba's modified k-ratio method is the most practical for uncertainty quantification of βeff. Finally, total βeff uncertainty due to nuclear data for the VENUS-F critical configuration is determined to be approximately 2.7% with JENDL-4.0u, which is dominated by the delayed neutron yield of 235U. 相似文献
65.
Saeko Yanaka Shigetaka Nishiguchi Rina Yogo Hiroki Watanabe Jiana Shen Hirokazu Yagi Takayuki Uchihashi Koichi Kato 《International journal of molecular sciences》2022,23(4)
Immunoglobulin G (IgG) adopts a modular multidomain structure that mediates antigen recognition and effector functions, such as complement-dependent cytotoxicity. IgG molecules are self-assembled into a hexameric ring on antigen-containing membranes, recruiting the complement component C1q. In order to provide deeper insights into the initial step of the complement pathway, we report a high-speed atomic force microscopy study for the quantitative visualization of the interaction between mouse IgG and the C1 complex composed of C1q, C1r, and C1s. The results showed that the C1q in the C1 complex is restricted regarding internal motion, and that it has a stronger binding affinity for on-membrane IgG2b assemblages than C1q alone, presumably because of the lower conformational entropy loss upon binding. Furthermore, we visualized a 1:1 stoichiometric interaction between C1/C1q and an IgG2a variant that lacks the entire CH1 domain in the absence of an antigen. In addition to the canonical C1q-binding site on Fc, their interactions are mediated through a secondary site on the CL domain that is cryptic in the presence of the CH1 domain. Our findings offer clues for novel-modality therapeutic antibodies. 相似文献
66.
We previously demonstrated that the organogermanium compound 3-(trihydroxygermyl)propanoic acid (THGP) enhances the enzymatic and alkaline isomerization of an aldose to a ketose through cis-diol complex formation by multiple mechanisms. Its higher affinity for the ketose than the aldose protects the ketose complex from alkaline decomposition. Furthermore, it has been reported that the aldose-ketose alkaline isomerization pathway includes 1,2-enediol. Therefore, we speculated that the complex-forming ability of THGP could also be applied to enediol, a transient intermediate of alkaline isomerization. To test this prediction, we analyzed the initial rates of glucose or lactose isomerization in a region where there was no substantial difference in pH with and without THGP addition. The results showed that THGP enhanced the rate of fructose or lactulose formation per unit time by approximately 2-fold compared to the control. This finding indicated that THGP could form a complex with the transition state of aldose-ketose alkaline isomerization. 相似文献
67.
Koichi Mitsukura Hiromu Sakamoto Haruka Kubo Toyokazu Yoshida Toru Nagasawa 《Journal of Bioscience and Bioengineering》2010,109(6):550-553
To efficiently produce 1,3-adamantanediol (1,3-ad(OH)2) from 1-adamantanol (1-adOH), our stocks of culture strains and soil microorganisms were surveyed for hydroxylation activity towards 1-adOH. Among them, the soil actinomycete SA8 showing the highest hydroxylation activity was identified as Streptomyces sp. based on 16S ribosomal DNA sequence analysis. The reaction products were purified by silica gel column chromatography, and from NMR and MS analyses, they were identified as 1,3-ad(OH)2 and 1,4-ad(OH)2. Streptomyces sp. SA8 produced 5.9 g l? 1 1,3-ad(OH)2from 6.2 g l? 1 1-adOH in culture broth after 120 h at 25 °C. Using resting cells, 2.3 g l? 1 1,3-ad(OH)2 was produced after 96 h of incubation at a 69% conversion rate. In both cases, 1,4-ad(OH)2 was formed as a byproduct at a rate of about 15%. Strain SA8 also hydroxylated 2-adamantanol and 2-methyl-2-adamantanol. 相似文献
68.
Hiroki Ishikawa Ryoko Komaki Haruo Naitoh Akira Yamaba Hiroki Katoh 《Electrical Engineering in Japan》2010,173(1):51-59
This paper presents a current control design for switched reluctance motors (SRMs). The electric transfer characteristic of the motors is studied first. Their transfer function is shown to be expressible by a pure resistive component, which is not constant but varies depending on the motor current and speed. The current control design for SRMs follows the classical design technique used for DC machines, where the zeros of the PI controller cancel the poles of Ls+R. Because the transfer function of SRMs does not have any poles, an I controller is suitable for them. The integral gain should be adjusted in order to compensate the nonlinearity, that is, the variation in the equivalent resistor of the SRMs' transfer function. The values of the integral gain are tuned and tabulated for the motor speed and current. Simulation and experiment demonstrate that the current and speed of the SRMs present good responses without dependence on the motor speed and current. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(1): 51–59, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20987 相似文献
69.
Koh Matsumoto Kazutada Ikenaga Jun Yamamoto Kazuki Naito Yoshiki Yano Akinori Ubukata Hiroki Tokunaga Tadanobu Arimura Katsuaki Cho Toshiya Tabuchi Akira Yamaguchi Yasuhiro Harada Yuzaburo Ban Kousuke Uchiyama 《半导体学报》2011,32(1):21-23
Growth rate has a direct impact on the productivity of nitride LED production.Atmospheric pressure growth of GaN with a growth rate as high as 10μm/h and also Al0.1Ga0.9N growth of 1μm/h by using 4 inch by 11 production scale MOVPE are described.XRD of(002) and(102) direction was 200 arcsec and 250 arcsec, respectively.Impact of the growth rate on productivity is discussed. 相似文献
70.
Hironao Ogura Hiroki Ishida Ryuta Yokooji Hiroyuki Kage Yoshizo Matsuno Arun S. Mujumdar 《Drying Technology》2001,19(7):1461-1477
The authors have been studying Chemical Heat Pumps (CHP) from the viewpoints of energy saving and environmental impact. The CHP can store thermal energy in the form of chemical energy by an endothermic reaction, and release it at various temperature levels during heat demand periods by exo/endothermic reactions. The authors have proposed in an earlier study a novel chemical heat pump (CHP) system for environmentally-friendly effective utilization of thermal energy in drying as a chemical heat pump dryer (CHPD). In this exploratory study, we test the effectiveness of operating the proposed CHPDs experimentally. Basic experiments on the CHPDs such as hot dry air production for convective drying are performed on lab-scale CHPD apparatuses using gas-solid reactions in calcium oxide/calcium hydroxide reactant beds. The proposed CHPDs are found to produce hot air by CHP operation for drying. The temperature levels of the produced hot air and the reaction rates/conversions are as good as in the case of hot water supply system using basically same CHP operation. The cold heat for air dehumidification is also found to be generated/recovered by the same CHPD system. The generated heat amounts can be increased by changing the operating conditions although the heat recovery must be enhanced for practical application of CHPDs. 相似文献