全文获取类型
收费全文 | 415篇 |
免费 | 34篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 8篇 |
化学工业 | 167篇 |
金属工艺 | 7篇 |
机械仪表 | 5篇 |
建筑科学 | 6篇 |
能源动力 | 18篇 |
轻工业 | 29篇 |
无线电 | 30篇 |
一般工业技术 | 55篇 |
冶金工业 | 51篇 |
原子能技术 | 5篇 |
自动化技术 | 69篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 7篇 |
2018年 | 14篇 |
2017年 | 17篇 |
2016年 | 10篇 |
2015年 | 11篇 |
2014年 | 17篇 |
2013年 | 27篇 |
2012年 | 24篇 |
2011年 | 14篇 |
2010年 | 11篇 |
2009年 | 18篇 |
2008年 | 16篇 |
2007年 | 16篇 |
2006年 | 22篇 |
2005年 | 22篇 |
2004年 | 16篇 |
2003年 | 15篇 |
2002年 | 12篇 |
2001年 | 6篇 |
2000年 | 8篇 |
1999年 | 9篇 |
1998年 | 24篇 |
1997年 | 10篇 |
1996年 | 12篇 |
1995年 | 9篇 |
1994年 | 8篇 |
1993年 | 11篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 10篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1978年 | 3篇 |
1976年 | 4篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有450条查询结果,搜索用时 15 毫秒
41.
Weinstein Herbert Fu Benedict S. Acosta Raul Bernstein Barry Shaffer Aaron B. 《IEEE transactions on bio-medical engineering》1973,(4):269-277
A method is developed for analyzing sudden injection dye (tracer) curves in order to obtain the distribution of first passage times in the mammalian circulation. The moments of the distribution yield useful quantities such as circulating blood volume. The method involves the use of Liouville-Neumann series. The calculation of the first passage time distribution (FPD) also requires a deconvolution through the use of Fourier transforms, but the calculation of moments does not. 相似文献
42.
In the present work, the changed properties of isotactic polypropylene caused by adding untreated sepiolite and n-decylaldehyde treated sepiolite were analyzed by studying the isothermal crystallization processes and the dynamic properties of the resulting composites. Variations in the surface activity of the n-decylaldehyde treated sepiolite leads to significant changes in the measured properties compared to those observed in the composites containing untreated sepiolite. This allows the assumption that the structure of the interface filler/polymer is modified as a function of filler activity. 相似文献
43.
44.
The reaction between acroleindiethylacetal (3.3-diethoxypropene) and free radicals and the behaviour of this acetal in the free radical copolymerization with unsaturated monomers has been investigated. The decomposition of benzoyl peroxide and tert.-butyl peroxide in acroleindiethylacetal has been studied in the liquid phase. On the basis of the obtained products a mechanism is proposed which involves the abstraction of a hydrogen atom by a primary radical from a carbon atom which is adjacent to oxygen. We also tried to copolymerize the acetal with several conventional comonomers but copolymers were only obtained when acrylonitrile and maleic anhydride were used. The remarkably uniform composition of the copolymers from the acetal and maleic anhydride is explained through a donor-acceptor complex between the two monomers. 相似文献
45.
Acosta EJ Nguyen T Witthayapanyanon A Harwell JH Sabatini DA 《Environmental science & technology》2005,39(5):1275-1282
In this work we have studied the formulation of biocompatible microemulsions using lecithin as the main surfactant and bio-compatible linker molecules (hexyl polyglucoside asthe hydrophilic linker and sorbitan monoleate as the lipophilic linker). These bio-compatible systems are discussed as potential substitutes for chlorinated solvents in dry-cleaning applications and as solvent delivery systems for pharmaceutical applications. Formulation parameters and conditions were evaluated using isopropyl myristate (IPM) as the model oil. It was found that the proposed linker-based formulations were able to form alcohol-free microemulsions while achieving higher solubilization capacity than similar systems reported in the literature. In addition, these lecithin/linker formulations were able to form microemulsions with a wide range of oils, from polar chlorinated hydrocarbons to hydrophobic oils such as squalene. These microemulsions were achieved under isotonic conditions (0.9% NaCl) by only varying the relative proportions of the linkers. The "solvency" power of these bio-compatible formulations was tested for the removal of hexadecane (used as model oil) from cotton fabrics and compared to the solvency power of a typical dry cleaning solvent tetrachloroethylene (PCE). While PCE and the linker-based lecithin formulation removed the same amount of hexadecane at low loading ratios (less than 1% oil volume fraction), at higher loading ratios the linker-based lecithin formulation retained its oil removal capacity while the efficiency of the PCE system declined rapidly. These initial results thus demonstrate the remarkable oil solubilization capacity of these bio-compatible linker-based lecithin formulations and illustrate their potential as environmentally friendly replacements for organic solvents. 相似文献
46.
This paper reports on a study of dynamic moduli and thermal transitions of poly(vinylidene fluoride) in compatible blends with poly(methylmethacrylate) and in non-compatible blends with polystyrene. The effects of sepiolite on the compatibility of these blends have been studied. 相似文献
47.
Antonio J. Lopez‐Martin Lucia Acosta Coro Garcia‐Alberdi Ramon G. Carvajal Jaime Ramirez‐Angulo 《International Journal of Circuit Theory and Applications》2012,40(11):1143-1163
A class AB version of the conventional super source follower (SSF) is described. The circuit greatly increases slew rate (SR) and current efficiency, maintaining the low distortion and low output resistance of the SSF. Class AB operation is achieved without extra power dissipation or supply requirements, and without bandwidth or noise degradation. The circuit can advantageously replace the SSF in a wide variety of analog systems, opening a new research line in analog design. To illustrate the widespread application of this cell, a class AB differential unity‐gain buffer, a class AB differential current mirror and two class AB differential transconductors are designed, fabricated in a 0.5µm CMOS technology and tested. Measurement results using a dual supply of ±1.65V show that the proposed class AB version of the SSF improves SR by a factor 21.5 and increases bandwidth by 10%, keeping noise level, input range, power consumption, and supply requirements unaltered. The fabricated class AB current mirror features a THD at 100 kHz of ? 62dB for signal currents 20 times larger than the bias current. The fabricated transconductors feature an IM3 at 1 MHz of ? 56.6dB for output currents more than 13 times larger than the bias currents. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
48.
Wook Jo Robert Dittmer Matias Acosta Jiadong Zang Claudia Groh Eva Sapper Ke Wang Jürgen R?del 《Journal of Electroceramics》2012,29(1):71-93
In response to the current environmental regulations against the use of lead in daily electronic devices, a number of investigations have been performed worldwide in search for alternative piezoelectric ceramics that can replace the market-dominating lead-based ones, representatively Pb(Zr x Ti1-x )O3 (PZT)-based solid solutions. Selected systems of potential importance such as chemically modified and/or crystallographically textured (K, Na)NbO3 and (Bi1/2Na1/2)TiO3-based solid solutions have been developed. Nevertheless, only few achievements have so far been introduced to the marketplace. A recent discovery has greatly extended our tool box for material design by furnishing (Bi1/2Na1/2)TiO3-based ceramics with a reversible phase transition between an ergodic relaxor state and a ferroelectric with the application of electric field. This paired the piezoelectric effect with a strain-generating phase transition and extended opportunities for actuator applications in a completely new manner. In this contribution, we will present the status and perspectives of this new class of actuator ceramics, aiming at covering a wide spectrum of topics, i.e., from fundamentals to practice. 相似文献
49.
Rizwan Ahmed Malik Ali Hussain Matias Acosta John Daniels Hyoung-Su Han Myong-Ho Kim Jae-Shin Lee 《Journal of the European Ceramic Society》2018,38(6):2511-2519
In this work, the relationship between the structural mechanisms and macroscopic electrical properties of the Nb-modified 0.96(Bi0.5Na0.84K0.16TiO3)–0.04SrTiO3 (BNKT–ST) system were elucidated by using temperature dependent and in situ synchrotron X-ray diffraction (XRD) techniques. For the composition x?=?0.0175, a large-signal piezoelectric coefficient (Smax/Emax?=?d33*) of 735 pm?V?1 at 6?kV mm?1 was observed at room temperature. Interestingly, at a higher temperature of 110?°C, the sample still showed a large d33* of 570 pm V?1. Furthermore, the temperature-invariant electrostrictive coefficient for this sample was found to be 0.0285?m4?C?2 over the temperature range of 25–170?°C. Moreover, the energy density for x?=?0.030 sample was ~1.0?J?cm?3 with an energy storage efficiency of ?70% in the temperature range of 25–135?°C. These results suggest that the synthesized Nb-modified BNKT–ST system is promising for the design of ceramic actuators as well as capacitor applications. 相似文献
50.