全文获取类型
收费全文 | 1472篇 |
免费 | 42篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 20篇 |
化学工业 | 253篇 |
金属工艺 | 30篇 |
机械仪表 | 25篇 |
建筑科学 | 48篇 |
矿业工程 | 9篇 |
能源动力 | 30篇 |
轻工业 | 148篇 |
水利工程 | 9篇 |
石油天然气 | 3篇 |
无线电 | 145篇 |
一般工业技术 | 212篇 |
冶金工业 | 410篇 |
原子能技术 | 9篇 |
自动化技术 | 165篇 |
出版年
2022年 | 12篇 |
2021年 | 30篇 |
2020年 | 23篇 |
2019年 | 14篇 |
2018年 | 36篇 |
2017年 | 19篇 |
2016年 | 9篇 |
2015年 | 12篇 |
2014年 | 28篇 |
2013年 | 61篇 |
2012年 | 32篇 |
2011年 | 66篇 |
2010年 | 40篇 |
2009年 | 45篇 |
2008年 | 55篇 |
2007年 | 42篇 |
2006年 | 51篇 |
2005年 | 41篇 |
2004年 | 27篇 |
2003年 | 26篇 |
2002年 | 41篇 |
2001年 | 30篇 |
2000年 | 17篇 |
1999年 | 29篇 |
1998年 | 93篇 |
1997年 | 54篇 |
1996年 | 51篇 |
1995年 | 28篇 |
1994年 | 33篇 |
1993年 | 41篇 |
1992年 | 26篇 |
1991年 | 20篇 |
1990年 | 32篇 |
1989年 | 20篇 |
1988年 | 24篇 |
1987年 | 21篇 |
1986年 | 11篇 |
1985年 | 24篇 |
1984年 | 20篇 |
1983年 | 16篇 |
1982年 | 19篇 |
1981年 | 13篇 |
1980年 | 14篇 |
1979年 | 14篇 |
1978年 | 8篇 |
1977年 | 24篇 |
1976年 | 22篇 |
1975年 | 13篇 |
1974年 | 14篇 |
1973年 | 10篇 |
排序方式: 共有1516条查询结果,搜索用时 312 毫秒
91.
Photorealistic rendering of graphical models continues to be a topic of considerable research effort in the computer graphics community. However, photorealism isn't the only criterion for judging an image's value. In visualization, where rendering is the conduit through which abstract, nonrealistic forms (such as isosurfaces or streamtubes) become perceivable to users, photorealism may neither be the most useful nor appropriate property. This article describes our long-term research vision in an area that, in our view, should gain a lot of importance in the future 相似文献
92.
93.
We present a study of the infrared reflectance of porous silicon carbide (PSC) formed by the electrochemical dissolution of silicon carbide substrates of both 6H and 4H polytypes. The reflectance from n-PSC, both as-anodized and passivated, is reported for the first time. The passivation of PSC has been accomplished using a short thermal oxidation. Fourier transform infrared (FTIR) reflectance spectroscopy is employed ex situ after different stages of the thermal oxidation process. The characteristics of the reststrahlen band normally observed in bulk SiC are altered by anodization; further changes in the reflectance spectra occur following oxidation for different periods of time. An effective medium theory model that includes air, SiC and SiO2 as component materials is shown to characterize the observed changes in the reflectance spectra after different stages of PSC oxidation. 相似文献
94.
Andrew P. ChafinMatthew C. Davis William W. LaiGeoffrey A. Lindsay Dong H. ParkWarren N. Herman 《Optical Materials》2011,33(8):1307-1315
Molecular first hyperpolarizabilities and dipole moments of new benzo-fused dyes were calculated using quantum-mechanical density functional theory (DFT). Two new infrared dyes were synthesized: each one was terminated with 6-diethylaminobenzo[b]furan on one end, and with CF3-tricyanodihydrofuran on the other end. The midsection of the π-electron framework for one dye contained a morpholino-substituted cyclohexenylene unit, and the other dye contained an ethoxysiloxane-substituted cyclohexenylene unit. Guest-host films were deposited on ITO-glass and contact poled. Electro-optic coefficients (r33) were measured at a wavelength of 1550 nm by the attenuated total reflection method and by a modified simple Teng-Man reflection method. The measured values of r33 were compared with values estimated from a well-known model that employs the molecular properties of the dyes and the film poling parameters. Thermal stability and electronic absorption spectra of the dyes were measured. 相似文献
95.
Herman Doffiné 《Holz als Roh- und Werkstoff》1961,19(4):129-136
Ohne Zusammenfassung
H. Gebhardt, H. v. Grudzinski u. H. Matz: Vergleich zwischen der europ?ischen und der amerikanischen Sperrholzindustrie, Holz als Roh- u. Werkstoff Bd.9 (1951) S. 190/193.—Dieselben: Herstellungsmethoden in amerikanischen Sperrholzfabriken. Holz als Roh- u. Werkstoff Bd.9 (1951)S. 273/278.—Dieselben: Erzeugnisse der nordamerikanischen Sperrholzindustrie. Holz als Roh- u. Werkstoff Bd.9 (1961) S. 348/351.—Dieselben: Folgerungen aus einer kritischen Betrachtung der Arbeitsmethoden in der amerikanischen Sperr-Roh- und Werkstoff Bd.9 (1951) S. 391/395. 相似文献
Tendencies in the American plywood industry
H. Gebhardt, H. v. Grudzinski u. H. Matz: Vergleich zwischen der europ?ischen und der amerikanischen Sperrholzindustrie, Holz als Roh- u. Werkstoff Bd.9 (1951) S. 190/193.—Dieselben: Herstellungsmethoden in amerikanischen Sperrholzfabriken. Holz als Roh- u. Werkstoff Bd.9 (1951)S. 273/278.—Dieselben: Erzeugnisse der nordamerikanischen Sperrholzindustrie. Holz als Roh- u. Werkstoff Bd.9 (1961) S. 348/351.—Dieselben: Folgerungen aus einer kritischen Betrachtung der Arbeitsmethoden in der amerikanischen Sperr-Roh- und Werkstoff Bd.9 (1951) S. 391/395. 相似文献
96.
Deduction Graphs are meant to generalise both Gentzen-Prawitz style natural deductions and Fitch style flag deductions. They have the structure of acyclic directed graphs with boxes. In [Herman Geuvers and Iris Loeb. Natural Deduction via Graphs: Formal Definition and Computation Rules. Mathematical Structures in Computer Science (Special Issue on Theory and Applications of Term Graph Rewriting), Volume 17(03):485–526, 2007.] we have investigated the deduction graphs for minimal proposition logic. This paper studies the extension with first-order universal quantification, showing the robustness of the concept of deduction graphs. 相似文献
97.
Ananth Dodabalapur V. P. Kesan D. P. Neikirk B. G. Streetman M. H. Herman I. D. Ward 《Journal of Electronic Materials》1990,19(3):265-270
In this study, we describe the correlations between the photoluminescence (PL) spectra and electrical properties of pseudomorphic
modulation-doped AlGaAs/InGaAs/GaAs quantum wells (MDQWs) grown by molecular beam epitaxy. In MDQWs, the presence of a large
sheet carrier density contributes significantly to the PL linewidth. At low temperatures (4.2 K), free carrier induced broadening
of the PL linewidth is influenced by the material quality of the structure. At higher temperatures (77 K), differences in
the material quality do not affect the linewidth significantly, and under these conditions the PL linewidth is a good measure
of the sheet carrier density. The ratio of the 77 K to 4.2 K PL linewidths provides useful information about the crystalline
quality of the MDQW structures as illustrated by the correlation with 77 K Hall mobility data and a simple model. We present
results of Electron Beam Electroreflectance (EBER) to characterize MDQWs and undoped quantum wells in the AlGaAs/InGaAs/GaAs
material system. Several transitions have been observed and fitted to excitonic Lorentzian lineshapes, providing accurate
estimates of transition energy and broadening parameter at temperatures of 96 K and 300 K. 相似文献
98.
99.
A Flotronic silver membrane has been used as a vehicle to process, via freeze substitution, collagenase-derived rabbit pancreatic islets. The procedure provides: (1) a simple, inexpensive method for handling larger numbers of tightly clustered islet aggregates; (2) a metal surface for rapid heat transfer from specimen to cryogen resulting in an increased circumferential zone of fine structural preservation; (3) the elimination of possible artifacts associated with impact or rotation of biological specimens against a cooled, highly polished metal block; (4) superior preservation of structural components not usually observed by conventional modes of fixation; (5) retention of metabolic components which may subsequently be available for immunocytochemical or X-ray energy dispersive procedures. 相似文献
100.
Lijffijt Marijn; Kenemans J. Leon; Verbaten Marinus N.; van Engeland Herman 《Canadian Metallurgical Quarterly》2005,114(2):216
This review discusses whether deficient inhibitory motor control is the core deficit of attention-deficit/hyperactivity disorder (ADHD). Inhibitory motor control is commonly assessed using the stop-signal paradigm. Since the last meta-analysis that was performed, 33 new studies have appeared. The current meta-analysis revealed a significant difference between ADHD patients and matched controls in stop latency (stop-signal reaction time) in both children and adults. Basic reaction time was significantly longer in children with ADHD, but not in adults, and there was a significant interaction between the elongation of the latency to stop and to respond in adults, but not in children. Deficient inhibitory motor control may be less crucial in children than in adults with ADHD. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献