全文获取类型
收费全文 | 641篇 |
免费 | 18篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 33篇 |
化学工业 | 169篇 |
金属工艺 | 13篇 |
机械仪表 | 43篇 |
建筑科学 | 16篇 |
能源动力 | 28篇 |
轻工业 | 54篇 |
水利工程 | 3篇 |
无线电 | 46篇 |
一般工业技术 | 132篇 |
冶金工业 | 35篇 |
原子能技术 | 11篇 |
自动化技术 | 77篇 |
出版年
2023年 | 2篇 |
2021年 | 15篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 8篇 |
2017年 | 12篇 |
2016年 | 6篇 |
2015年 | 9篇 |
2014年 | 11篇 |
2013年 | 35篇 |
2012年 | 29篇 |
2011年 | 34篇 |
2010年 | 24篇 |
2009年 | 28篇 |
2008年 | 51篇 |
2007年 | 49篇 |
2006年 | 33篇 |
2005年 | 30篇 |
2004年 | 14篇 |
2003年 | 22篇 |
2002年 | 24篇 |
2001年 | 20篇 |
2000年 | 13篇 |
1999年 | 9篇 |
1998年 | 26篇 |
1997年 | 10篇 |
1996年 | 14篇 |
1995年 | 10篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 9篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有660条查询结果,搜索用时 15 毫秒
651.
We focus on condensation and collapse processes of vapor bubble(s) in a subcooled pool. We generate the vapor in the vapor
generator and inject it/them to form vapor bubble(s) at a designated temperature into the liquid at a designated degree of
subcooling. In order to evaluate the effect of induced flow around the condensing/collapsing vapor bubble, two different boundary
conditions are employed; that is, the vapor is injected through the orifice and the tube. We also focus on interaction between/among
the condensing/collapsing vapor bubbles laterally injected to the pool. Through this system we try to simulate an interaction
between the vapor bubble and the subcooled bulk in a complex boiling phenomenon, especially that known as MEB (microbubble
emission boiling) in which a higher heat flux than critical heat flux (CHF) accompanying with emission of micrometer-scale
bubbles from the heated surface against the gravity is realized under a rather high subcooled condition. 相似文献
652.
Yuya Kasho Hidetoshi Hirai Masanori Tsukuda Ichiro Omura 《Microelectronics Reliability》2011,51(9-11):1689-1692
“Stealth” electric current probing technique for power electronics circuits, power device modules and chips makes it possible to measure electric current without any change or disassembling the circuit and the chip connection for the measurement. The technique consists of a tiny-scale magnetic-field coil, a high speed analog amplifier and a digitizer with numerical data processing. This technique can be applied to a single bonding wire current measurement inside IGBT modules, chip scale current redistribution measurement and current measurement for surface mount devices. The “stealth” current measurement can be utilized in the failure mechanism understanding of power devices including IGBT short circuit destruction. 相似文献
653.
Ultrafast Terahertz Gating of the Polarization and Giant Nonlinear Optical Response in BiFeO3 Thin Films 下载免费PDF全文
654.
Kazuya Nishina Shigeto Sudo Kazuyuki Yagi Tomohito Sano Yusuke Takata Hiroshi Obara Sadao Eguchi Noriko Oura Shinji Yano Satoru Ohkoshi Yutaka Fujita Yutaka Shiratori Masaki Tsuji Hiroyuki Hasukawa Yasufumi Suzue Yasunao Yamada Hiroyuki Mizukami Ichiro Uezono 《Nutrient Cycling in Agroecosystems》2015,103(1):87-99
655.
We synthesized a conjugate in which gelatin was covalently crosslinked to agarose using 1,1-carbonyldiimidazole (CDI) in dimethyl sulfoxide in order to obtain gels with cellular adhesiveness that showed a sol-to-gel transition, but no gel-to-sol transition, around body temperature. The gelatin content of the conjugate increased by 2.7-fold when the concentration of CDI was increased from 1.3 to 32.7 mM. Aqueous solutions of the conjugate gelled upon cooling from 40 degrees C to 20 degrees C, but did not remelt at 37 degrees C. The percentage of adhered cells after 4 h of culture on a gel created from a conjugate containing about 25 wt% gelatin was similar to that for cells grown on tissue culture dishes. The adhered cells proliferated on the conjugate gel during culture for a further 5 d. In addition, the conjugate used in this study did not result in mechanical instability of the resultant gel compared to that of an unmodified agarose gel. These results demonstrate that this agarose-gelatin conjugate is a good candidate material for tissue engineering. 相似文献
656.
Shin‐Ichiro Tanifuji Tsuyoshi Kikuchi Jun‐Ichi Takimoto Kiyohito Koyama 《Polymer Engineering and Science》2000,40(8):1878-1893
This paper focuses on the overall numerical simulation of the parison formation and inflation process of extrusion blow molding. The competing effects due to swell and drawdown in the parison formation process were analyzed by a Lagrangian Eulerian (LE) finite element method (FEM) using an automatic remeshing technique. The parison extruded through an annular die was modeled as an axisymmetric unsteady nonisothermal flow with free surfaces and its viscoelastic properties were described by a K‐BKZ integral constitutive equation. An unsteady die‐swell simulation was performed to predict the time course of the extrudate parison shape under the influence of gravity and the parison controller. In addition, an unsteady large deformation analysis of the parison inflation process was also carried out using a three‐dimensional membrane FEM for viscoelastic material. The inflation sequence for the parison molded into a complex‐shaped mold cavity was analyzed. The numerical results were verified using experimental data from each of the sub‐processes. The greatest advantage of the overall simulation is that the variation in the parison dimension caused by the swell and drawdown effect can be incorporated into the inflation analysis, and consequently, the accuracy of the numerical prediction can be enhanced. The overall simulation technique provides a rational means to assist the mold design and the determination of the optimal process conditions. 相似文献
657.
Masakazu Michihira Mitsuo Ueda Tsuyoshi Funaki Zen‐Ichiro Kawasaki Kenji Matsu‐ura 《Electrical Engineering in Japan》2000,130(2):88-98
In recent years, the soft‐switching techniques have attracted attention for their peculiar advantages such as low switching loss, high power density, EMI/RFI noise reduction, and so on. The authors have previously reported on a quasi‐resonant dc–dc converter using new phase‐shift PWM control scheme. By using the proposed control scheme, circulating current is eliminated and ZVS (Zero Voltage Switching) is achieved with small commutating current. As a result, the conduction losses caused by their currents are substantially reduced. In this paper, the authors apply a proposed control scheme to a quasi‐resonant high‐frequency transformer link dc–ac converter. As a result, all switching devises in this dc–ac converter can achieve soft switching with small commutating current irrespective of inverter mode and rectifier mode. Its operating principle and unique features are described as compared with the symmetrical control scheme of dc–ac converter. Operating performance of this dc–ac converter in the steady state is illustrated by means of simulation results. © 1999 Scripta Technica, Electr Eng Jpn, 130(2): 88–98, 2000 相似文献
658.
Ichiro Minami 《Lubrication Science》1995,7(4):319-331
The addition of more antioxidant to aged oils is not always effective in preventing autoxidation. To investigate this phenomenon, a solution of antioxidant and model oxide in hexadecane was examined by means of the induction period method. Aldehydes were found to be the most active species for reducing the antioxidation properties of zinc dialkyldithiophosphate (ZDTP), 2,6-di(tert. butyl)-4-methylphenol (DBPC), and N-phenyl-1-naphtylamine (PNA). Carboxylic acids, ethers, alcohols, and ketones to some extent reduced the induction period with these antioxidants. Esters showed almost no influence on reducing their antioxidant properties. Reaction of ZDTP with aldehyde was studied by means of 31P-NMR analysis. It was found that (a) aldehydes accelerate conversion of ZDTP, and thereby reduce its antioxidant performance. (b) Conversion of ZDTP in the presence of aldehydes under oxygen at 130° in hexadecane and no reaction was observed under nitrogen at the same temperature. Active intermediates derived by the autoxidation of aldehyde were suspected. (c) Reaction of peroxycarboxylic acid with ZDTP took place smoothly at 0°C under nitrogen to give bis(dialkylthiorophosphoro)disulphide and the corresponding carboxylic acid. Reaction of hydroperoxide with ZDTP took place at room temperature to give oxo-hexa(dialkylphosphorothiorothionato)-tetrazinc. Two mechanisms for decomposition of ZDTP promoted by aldehydes, namely hydroperoxide and peroxycarboxylic acid mechanisms, are proposed. Reaction of peroxycarboxylic acid with DBPC or PNA barely took place at room temperature: for these antioxidants, the peroxycarboxylic acid mechanism would be excluded. Radical species derived by the autoxidation of aldehydes were considered as active intermediates. It is considered that classification of the types of oxides that exist in used oils in the key to optimising the effect of re-added antioxidants. 相似文献
659.
Gopal Prasad Khanal Ichiro Fujii Shintaro Ueno Satoshi Wada 《Journal of the American Ceramic Society》2023,106(5):2930-2940
The 〈100〉 grain-oriented 0.11(Bi0.5K0.5)TiO3–0.23BaTiO3–0.02Bi(Mg0.5Ti0.5)O3–0.64BiFeO3 piezoelectric ceramics were prepared by a reactive templated grain growth method using a platelike H1.08Ti1.73O4·nH2O (HTO) template and Bi2O3–KHCO3–MgO–Fe2O3–BaCO3 matrix particles. The high degree of texturing (a Lotgering orientation factor of 80%) and high density (95%) were achieved by employing weight-pressing treatment during the binder-removal and sintering treatment along with optimizing the sintering temperature. The water-quenching treatment has a significant impact on the enhancement of dielectric, ferroelectric, and piezoelectric properties with the increase of dielectric constant, remanent polarization, and piezoelectric strain constant from 764, 13.6 μC/cm2, and 384 pm/V for the as-sintered ceramics to 812, 29.9 μC/cm2, and 526 pm/V after the water-quenching treatment at 850°C, respectively. The obtained piezoelectric strain constant with a 1.8 times enhancement compared to that of the ceramics with randomly oriented grains is significantly higher than those reported for other lead-free piezoelectric ceramics with Curie temperature >300°C. This study suggested the strong potentiality of this material system for high-temperature actuator application. 相似文献
660.
Shinya Sekizaki Teruyuki Kato Ichiro Nishizaki Tomohiro Hayashida Kazuhisa Hikoyama Tomoaki Nonoyama 《Electrical Engineering in Japan》2023,216(3):e23442
The service restoration to sound sections within a short period as much as possible, performed after the permanent fault occurs in a distribution system, is significant for maintaining power supply reliability. This paper proposes an efficient method to find service restoration procedures based on fault searching and the optimal work scheduling of crews, considering the power supply priorities of loads and the probability of occurrence of faults. The proposed method is composed of two-stage problems to reduce the outage sections efficiently: (i) the problem to find a series of searching procedures for unknown fault locations in the first stage and (ii) the optimization problem of work schedules of crews in the second stage. In the first stage, the order of operation of switches opened for searching for the fault direction is determined, constituting the searching tree. After that, the proposed optimization method can efficiently solve the work scheduling problem by formulating it as a mixed-integer linear programming problem in the second stage. The computational experiments using a large-scale distribution system model with many remote and manual switches show that the proposed method can provide efficient service restoration procedures within a reasonable computational time. 相似文献