全文获取类型
收费全文 | 4168篇 |
免费 | 105篇 |
国内免费 | 19篇 |
专业分类
电工技术 | 41篇 |
综合类 | 7篇 |
化学工业 | 739篇 |
金属工艺 | 78篇 |
机械仪表 | 68篇 |
建筑科学 | 208篇 |
矿业工程 | 15篇 |
能源动力 | 151篇 |
轻工业 | 329篇 |
水利工程 | 20篇 |
石油天然气 | 19篇 |
无线电 | 367篇 |
一般工业技术 | 592篇 |
冶金工业 | 1103篇 |
原子能技术 | 50篇 |
自动化技术 | 505篇 |
出版年
2023年 | 30篇 |
2022年 | 48篇 |
2021年 | 64篇 |
2020年 | 50篇 |
2019年 | 52篇 |
2018年 | 54篇 |
2017年 | 55篇 |
2016年 | 66篇 |
2015年 | 50篇 |
2014年 | 81篇 |
2013年 | 293篇 |
2012年 | 124篇 |
2011年 | 160篇 |
2010年 | 144篇 |
2009年 | 119篇 |
2008年 | 149篇 |
2007年 | 145篇 |
2006年 | 118篇 |
2005年 | 113篇 |
2004年 | 92篇 |
2003年 | 94篇 |
2002年 | 89篇 |
2001年 | 82篇 |
2000年 | 56篇 |
1999年 | 82篇 |
1998年 | 229篇 |
1997年 | 167篇 |
1996年 | 121篇 |
1995年 | 92篇 |
1994年 | 81篇 |
1993年 | 73篇 |
1992年 | 50篇 |
1991年 | 48篇 |
1990年 | 56篇 |
1989年 | 35篇 |
1988年 | 42篇 |
1987年 | 42篇 |
1986年 | 55篇 |
1985年 | 45篇 |
1984年 | 57篇 |
1983年 | 39篇 |
1982年 | 47篇 |
1981年 | 51篇 |
1980年 | 45篇 |
1979年 | 35篇 |
1978年 | 32篇 |
1977年 | 56篇 |
1976年 | 60篇 |
1975年 | 45篇 |
1974年 | 37篇 |
排序方式: 共有4292条查询结果,搜索用时 15 毫秒
1.
H. L. Du S. R. Rose Z. D. Xiang P. K. Datta X. Y. Li 《Materialwissenschaft und Werkstofftechnik》2003,34(4):421-426
The oxidation/sulphidation behaviour of a Ti‐46.7Al‐1.9W‐0.5Si alloy with a TiAl3 diffusion coating was studied in an environment of H2/H2S/H2O at 850oC. The kinetic results demonstrate that the TiAl3 coating significantly increased the high temperature corrosion resistance of Ti‐46.7Al‐1.9W‐0.5Si. The SEM, EDX, XRD and TEM analysis reveals that the formation of an Al2O3 scale on the surface of the TiAl3‐coated sample was responsible for the enhancement of the corroison resistance. The Ti‐46.7Al‐1.9W‐0.5Si alloy was also modified by Nb ion implantation. The Nb ion implanted and as received sampels were subjected to cyclic oxidation in an open air at 800oC. The Nb ion implantation not only increased the oxidation resistance but also substantially improved the adhesion of scale to the substrate. 相似文献
2.
This paper presents new inverse modeling for synchronous reluctance motor (SyRM). This modeling is valid when the inductances are sinusoidal or nonsinusoidal and even when the machine is saturated. This technique involves the generation of constant torque curves as a function of two-phase currents in the Concordia's reference frame when the rotor angle is fixed. We also introduce an experimental method to obtain directly the inverse modeling. This practical method takes into account the saturation of the motor. This technique allows the reduction of the low torque ripple in the case of nonsinusoidal inductances. 相似文献
3.
4.
5.
Ockene Judith K.; Kristeller Jean; Pbert Lori; Hebert James R.; Luippold Rose; Goldberg Robert J.; Landon Joan; Kalan Kathryn 《Canadian Metallurgical Quarterly》1994,13(3):278
Patterns of smoking cessation using 6- and 12-mo follow-up data are reported for 1,261 primary care patients randomized to 3 physician-delivered smoking interventions: advice only (AO), counseling (CI), and counseling plus availability of nicotine-containing gum (CI?+?NCG). One-week point-prevalence cessation rates at 12 mo did not differ among the interventions: AO (15.2%), CI (12.9%) and CI?+?NCG (16.7%). However, maintained cessation rates (abstinent at both 6 and 12 mo) increased with intervention intensity: AO (6.0%), CI (7.8%), and CI?+?NCG (10.0%): Test of trend χ–2?=?5.06, p?=?.02. CI?+?NCG was significantly higher than AO (p?=?.02). The findings support the following conclusions: Brief physician delivered intervention with availability of nicotine-containing gum can have a beneficial long-term effect on smoking cessation, and cohort data as well as point-prevalence rates are important when assessing the long-term impact of lifestyle interventions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
6.
Auguste Commeyras Hlne Collet Laurent Boiteau Jacques Taillades Odile Vandenabeele‐Trambouze Herv Cottet Jean‐Philippe Biron Raphaël Plasson Louis Mion Olivier Lagrille Herv Martin Franck Selsis Michel Dobrijevic 《Polymer International》2002,51(7):661-665
Addressing the still open question of the prebiotic origin of sequential macromolecules (peptides, nucleic acids) on the primitive Earth, we describe a molecular engine (the primary pump), which works at ambient temperature and continuously generates, elongates and complexifies sequential peptides. This new scenario is based on a cyclic reaction sequence, whose keystep is the activation of amino acids into their N‐carboxyanhydrides (NCA) through nitrosation by NOx. This process could have taken place on tidal beaches; it requires a buffered ocean, emerged land and a nitrosating atmosphere. With the help of geochemical studies and computer simulations of atmosphere photochemistry, we show that the primitive Earth during the Hadean may have satisfied all these requirements. © 2001 Society of Chemical Industry. 相似文献
7.
Raphaëlle Savoire Jean‐Louis Lanoisellé Hélène Ducatel Eugène Vorobiev 《European Journal of Lipid Science and Technology》2008,110(8):725-734
Seven linseed varieties were harvested at seven times before complete maturity. Microscale oilseed expressions were subsequently carried out on it. A pressure of 10 MPa was applied for 1 h under uniaxial stress. The results were characterized in terms of oil, water and mucilage content, harvest date and oil yield. The piston displacement versus time (creep curves) was described by a four‐Kelvin‐Voigt elements viscoelastic model. Parameters were derived from the model, such as the mechanical properties of seeds (compressibility moduli), showing that the viscoelastic model fits well the experimental data (R² ≈ 0.999). The modeling parameters were combined with some biochemical data in order to predict the kinetics of oil extraction. 相似文献
8.
9.
Sensors, mounted on the dexterous end of a robot, can be used for feedback control or calibration. When you mount a sensor on a robot it becomes necessary to find the pose (orientation and position) of the sensor relative to the robot. This is the sensor registration problem. Many researchers have provided closed-form solutions to the sensor registration problem; however, the published solutions apply only to sensors that can measure a complete pose (three positions and three orientations). Many sensors, however, can provide only position information; they cannot measure the orientation of an object. This article provides a closed-form solution to the sensor registration problem applicable when: (1) the sensor can provide only position information and (2) the robot can move along and rotate about straight lines. © 1994 John Wiley & Sons, Inc. 相似文献
10.