全文获取类型
收费全文 | 2420篇 |
免费 | 95篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 37篇 |
综合类 | 7篇 |
化学工业 | 633篇 |
金属工艺 | 45篇 |
机械仪表 | 49篇 |
建筑科学 | 113篇 |
矿业工程 | 4篇 |
能源动力 | 38篇 |
轻工业 | 143篇 |
水利工程 | 13篇 |
石油天然气 | 1篇 |
无线电 | 201篇 |
一般工业技术 | 436篇 |
冶金工业 | 494篇 |
原子能技术 | 7篇 |
自动化技术 | 302篇 |
出版年
2023年 | 35篇 |
2022年 | 40篇 |
2021年 | 57篇 |
2020年 | 39篇 |
2019年 | 37篇 |
2018年 | 55篇 |
2017年 | 40篇 |
2016年 | 75篇 |
2015年 | 49篇 |
2014年 | 77篇 |
2013年 | 110篇 |
2012年 | 96篇 |
2011年 | 128篇 |
2010年 | 81篇 |
2009年 | 89篇 |
2008年 | 99篇 |
2007年 | 92篇 |
2006年 | 90篇 |
2005年 | 77篇 |
2004年 | 60篇 |
2003年 | 54篇 |
2002年 | 69篇 |
2001年 | 46篇 |
2000年 | 44篇 |
1999年 | 52篇 |
1998年 | 131篇 |
1997年 | 73篇 |
1996年 | 58篇 |
1995年 | 49篇 |
1994年 | 42篇 |
1993年 | 29篇 |
1992年 | 25篇 |
1991年 | 23篇 |
1990年 | 26篇 |
1989年 | 19篇 |
1988年 | 25篇 |
1987年 | 33篇 |
1986年 | 21篇 |
1985年 | 22篇 |
1984年 | 21篇 |
1983年 | 22篇 |
1982年 | 22篇 |
1981年 | 14篇 |
1980年 | 13篇 |
1979年 | 16篇 |
1977年 | 11篇 |
1976年 | 29篇 |
1975年 | 12篇 |
1974年 | 16篇 |
1973年 | 13篇 |
排序方式: 共有2523条查询结果,搜索用时 0 毫秒
1.
2.
This study examines the links between antecedents and consequences of Gabonese teachers' (N= 152) work motivation. The theoretical underpinnings are based on the Motivational Model of Job Burnout (MMJB) which is grounded in Self-Determination Theory (SDT) and states that the more supervisors satisfy an employee's need for self-determination, competence, and relatedness, the more self-determined is the latter's work motivation. The level of self-determined motivation has an impact on job satisfaction, which in turn determines life satisfaction. Higher levels of self-determined motivation also buffer emotional exhaustion and psychological distress. The model was confirmed via structural equation modeling and provides support for the validity and generalizability of the MMJB and SDT. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
In this paper, we summarize our recent efforts to analyze transmission probabilities of extremely thin SiO2 gate oxides using microscopic models of Si[100]-SiO2-Si[100] heterojunctions. We predict energy-dependent tunneling masses and their influence on transmission coefficients, discuss tunneling probabilities and analyze effects arising from the violation of parallel momentum conservation. As an application of the present method, gate currents in short bulk MOSFETs are calculated, including elastic defect-assisted contributions. 相似文献
4.
Many-Body Terms in van der Waals Cohesion Energy of Nanotubes 总被引:2,自引:0,他引:2
We have developed a model for the calculation of van der Waals force for layered systems with axial symmetry. Our result can be applied to compute the cohesion of a carbon nanotube to a substrate, the cohesion between nanotubes, and between shells of multiwall nanotubes. We have obtained unusal power laws for the distance dependence of the many-body van der Waals potential. 相似文献
5.
6.
Many industrial processes and scientific experiments utilize large amounts of ac power at frequencies from 3 kHz to 500 kHz. The phase angle and the impedances of these loads often vary over a wide range. This paper describes an instrument to provide an accurate measurement of currents (1 A to 1000 A), voltages (100 V to 20 kV), and powers (100 W to 20 MW) over the frequency range from 25 kHz to 500 kHz. It deals with loads having power factors down to nearly zero and with load impedances from 10 Ω to 20 kΩ. The paper contains practical details of both the design and the calibration of the front-end voltage and current transducers. The characteristics of a nearly ideal broadband current transducer are presented. Overall instrument calibration, verification and traceability problems are considered in detail 相似文献
7.
OBJECTIVE: We report a case of candidiasis of the upper urinary tract that presented as acute renal failure associated with septic syndrome. The patient initially required hemodialysis. Right hydronephrosis and perirenal collection were observed on ultrasound examination. METHODS: A percutaneous nephrostomy was performed. Nephrostomy urine cytology and cultures were positive for Candida tropicalis. An anterograde pyelography showed a 'fungus ball' in the urinary tract. RESULTS: Therapy with oral fluconazole and percutaneous amphotericin B achieved excellent results. CONCLUSIONS: Candidiasic urinary infection of the upper urinary tract often produces obstructive uropathy requiring percutaneous nephrostomy, which can also be used to instill amphotericin B. Combination therapy with amphotericin B and fluconazole can achieve excellent results. 相似文献
8.
9.
10.
Dynamics of a single fluxon in an annular Josephson junction is studied in the presence of an externally applied magnetic
field H. Due to the interaction of the fluxon with the radial field component, the fluxon moves in a potential well which
height is proportional to H. Several spectacular features of fluxon dynamics analogous to the motion of a particle in a washboard
potential are clearly observed experimentally. Periodic revolutions of the fluxon in the junction lead to a potential induced
emission of plasma waves. These waves are indicated by a resonance at a certain fluxon velocity which depends on the junction
length. Good agreement between experiment, theoretical model and numerical simulations is found. 相似文献