全文获取类型
收费全文 | 3089篇 |
免费 | 207篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 18篇 |
综合类 | 2篇 |
化学工业 | 496篇 |
金属工艺 | 54篇 |
机械仪表 | 59篇 |
建筑科学 | 107篇 |
矿业工程 | 10篇 |
能源动力 | 46篇 |
轻工业 | 559篇 |
水利工程 | 25篇 |
石油天然气 | 11篇 |
无线电 | 134篇 |
一般工业技术 | 504篇 |
冶金工业 | 835篇 |
原子能技术 | 8篇 |
自动化技术 | 429篇 |
出版年
2024年 | 3篇 |
2023年 | 14篇 |
2022年 | 12篇 |
2021年 | 52篇 |
2020年 | 47篇 |
2019年 | 44篇 |
2018年 | 90篇 |
2017年 | 108篇 |
2016年 | 108篇 |
2015年 | 89篇 |
2014年 | 109篇 |
2013年 | 224篇 |
2012年 | 203篇 |
2011年 | 179篇 |
2010年 | 151篇 |
2009年 | 126篇 |
2008年 | 149篇 |
2007年 | 140篇 |
2006年 | 81篇 |
2005年 | 68篇 |
2004年 | 75篇 |
2003年 | 62篇 |
2002年 | 62篇 |
2001年 | 42篇 |
2000年 | 36篇 |
1999年 | 45篇 |
1998年 | 299篇 |
1997年 | 179篇 |
1996年 | 127篇 |
1995年 | 80篇 |
1994年 | 54篇 |
1993年 | 55篇 |
1992年 | 22篇 |
1991年 | 23篇 |
1990年 | 21篇 |
1989年 | 10篇 |
1988年 | 13篇 |
1987年 | 12篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1977年 | 9篇 |
1976年 | 24篇 |
1975年 | 3篇 |
1973年 | 2篇 |
1972年 | 2篇 |
排序方式: 共有3297条查询结果,搜索用时 12 毫秒
1.
2.
Hierarchical micro-nanostructured albite-based glass-ceramic for high dielectric strength insulators
V. Fuertes M.J. Cabrera J. Seores D. Muñoz J.F. Fernández E. Enríquez 《Journal of the European Ceramic Society》2018,38(7):2759-2766
A novel glass-ceramic material based on albite type Na-rich feldspar has been synthesized by conventional ceramic process. High crystallinity, >94%?Vol.% is obtained by fast sintering which allows energy saving processing. Albite is the main crystalline phase and tetragonal SiO2 is a secondary phase. Electrical properties were examined by complex impedance, DC measurements, and dielectric breakdown test. Dielectric characterization shows a non-Debye type dielectric behavior with low dielectric constant, 4.6 at 1?MHz, low dielectric losses, (~10?3 at 1?MHz, and a large dielectric strength, ~60?kV/mm), that it is the largest value reported in ceramic insulators. Those dielectric properties are attained by the low glassy phase content in the samples and their unique micro-nanostructure. All these properties make this novel material a very promising candidate in the market of ceramic electrical insulator, highlighting for high-voltage applications. 相似文献
3.
4.
Generation of Technology-Independent Retargetable Analog Blocks 总被引:1,自引:0,他引:1
R. Castro-López F. V. Fernández F. Medeiro A. Rodríguez-Vázquez 《Analog Integrated Circuits and Signal Processing》2002,33(2):157-170
This paper introduces a complete methodology for retargeting of analog cells to different sets of specifications. This methodology is technology-independent, thus allowing the migration, from one technology to another, of the circuit under retargeting. Careful integration of the device sizing and layout generation tasks via the incorporation of layout constraints during the sizing process allows to generate fully functional designs in a few minutes. The methodology is illustrated via the retargeting of a fully-differential Miller-compensated two-stage operational amplifier for a new set of specifications and two different technological processes.An erratum to this article can be found at 相似文献
5.
Vanesa Rodríguez-Amor Juan P. Fernández-Blázquez Antonio Bello Ernesto Pérez María L. Cerrada 《Polymer Bulletin》2008,60(1):89-96
Summary The effect of molecular weight on the uniaxial orientation process has been analyzed in two samples of thermotropic poly(diethylene
glycol p,p′-bibenzoate), evaluating the influence of that parameter on the type of orientation obtained. Several strain rates and deformation
temperatures have been tested in order to map out the conditions for obtaining the two different kinds of orientation. The
results show that in the lower molecular weight PDEB sample (Mw=31200) it is rather easy to get exclusively perpendicular “anomalous” orientation, with the molecular axes aligned transversely
to the stretching direction. However, it is extremely difficult to obtain 100% parallel “normal” orientation. On the contrary,
either type of orientation or a mixture of them can be easily developed for the higher molecular weight PDEB sample (Mw=102900). 相似文献
6.
Lie‐Fern Hsu 《Quality and Reliability Engineering International》2007,23(2):269-272
He and Grigoryan (Quality and Reliability Engineering International 2002; 18 :343–355) formulated the design of a double‐sampling (DS) s control chart as an optimization problem and solved it with a genetic algorithm. They concluded that the DS s control charts can be a more economically preferable alternative in detecting small shifts than traditional s control charts. We explain that, since they only considered the average sample size when the process is in control, their conclusion is questionable. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
7.
8.
C Fernández Pinilla M Luque Otero N Martell Claros JM Alcázar de la Osa JL Rodicio Díaz LM Ruilope Urioste 《Canadian Metallurgical Quarterly》1993,101(5):168-171
BACKGROUND: Hypertension and hypercholesterolemia are frequently associated with this leading to considerable cardiovascular risk. METHODS: An open parallel randomized study was performed in which the effects of doxazosin, an alpha-adrenergic blocker and enalapril, an inhibitor of the angiotensin converting enzyme were compared in 70 patients with essential high blood pressure and plasma cholesterol levels greater than 240 mg/dl. Following 2-4 weeks of placebo administration the patients were randomly treated with one of the two drugs. When required doses were increased and hydrochlorothiazide added until blood pressure lower than 160/95 mmHg was achieved. After this period the patients were observed for a minimum of 8 weeks. The mean length of the study was of 22 weeks. RESULTS: Both drugs significantly reduced blood pressure without modifying cardiac frequency. Doxazosin tended to favorably modify the lipid profile of the plasma while enalapril significantly reduced the levels of cholesterol, lipids and high density lipoproteins (HDL). Upon termination of the study the total HDL/cholesterol index increased 8.6% in those treated with doxazosin and decreased 5.5% in those receiving enalapril (p < 0.05). CONCLUSIONS: Although doxazosin and enalapril are potent antihypertensive drugs, the effects on plasma lipid obtained with doxazosin indicate that a reduction in cardiovascular risk was achieved with this drug in the patients included in this study. 相似文献
9.
10.