全文获取类型
收费全文 | 1015篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 71篇 |
综合类 | 5篇 |
化学工业 | 238篇 |
金属工艺 | 24篇 |
机械仪表 | 46篇 |
建筑科学 | 14篇 |
能源动力 | 88篇 |
轻工业 | 75篇 |
无线电 | 80篇 |
一般工业技术 | 188篇 |
冶金工业 | 51篇 |
原子能技术 | 49篇 |
自动化技术 | 106篇 |
出版年
2023年 | 5篇 |
2022年 | 17篇 |
2021年 | 15篇 |
2020年 | 11篇 |
2019年 | 8篇 |
2018年 | 12篇 |
2017年 | 15篇 |
2016年 | 19篇 |
2015年 | 17篇 |
2014年 | 25篇 |
2013年 | 57篇 |
2012年 | 34篇 |
2011年 | 60篇 |
2010年 | 45篇 |
2009年 | 54篇 |
2008年 | 64篇 |
2007年 | 54篇 |
2006年 | 34篇 |
2005年 | 45篇 |
2004年 | 50篇 |
2003年 | 43篇 |
2002年 | 26篇 |
2001年 | 28篇 |
2000年 | 21篇 |
1999年 | 23篇 |
1998年 | 19篇 |
1997年 | 28篇 |
1996年 | 27篇 |
1995年 | 20篇 |
1994年 | 15篇 |
1993年 | 4篇 |
1992年 | 9篇 |
1991年 | 11篇 |
1990年 | 3篇 |
1989年 | 8篇 |
1988年 | 13篇 |
1987年 | 10篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1974年 | 3篇 |
1966年 | 1篇 |
排序方式: 共有1035条查询结果,搜索用时 15 毫秒
91.
NiInGe ohmic contact materials, which are attractive to use in future GaAs devices, were previously developed in our laboratories.
Although the NiInGe contacts provided low contact resistances of about 0.3 Ω-mm and excellent thermal stability, further reduction
of the contact resistance (RC) of the NiInGe contacts was mandatory to use these contacts in submicron devices. In this paper, the microstructural parameters,
which influence the RC values, were investigated by correlating the RC values with the microstructure at the interface between the contact materials and the GaAs substrate. The RC values of the NiInGe contacts were found to depend strongly on the volume fraction and the In concentration (x) of the InxGa1−xAs compound semiconductor layers, which were formed at the metal/GaAs interface. Both the volume fraction and the In concentration
of the InxGa1−xAs layers were found to depend on the thickness of the In layer used in the NiInGe contact and the annealing temperature to
form the ohmic contact. A RC value of 0.18 Ω-mm was obtained for the Ni (18 nm)/In (13 nm)/Ge (30 nm) contact (where a slash “/” indicates the deposition
sequence) after annealing at temperature of 650°C for 5 sec. 相似文献
92.
The entropy and the mutual entropy for states and channels are totally studied in general quantum systems described byC*-algebras. In particular, we discuss the relations among theS-entropy and the mutual entropy introduced by Ohya and the Connes-Narnhofer-Thirring entropy. 相似文献
93.
94.
Any solution for an inverse heat conduction problem makes the estimation of surface temperature and surface heat flux worsen in the case where these values behave like a triangular shape change with time. In order to compensate for this defect, Monde and colleagues, who succeeded in obtaining analytical inverse solutions using the Laplace transform technique, introduce a new idea where these changes over the entire measurement time can be split into several parts depending on the behavior. Therefore, an approximate equation to trace the measured temperature change can be derived, resulting in good estimation of surface temperature and surface heat flux even in the case of the triangular shape change and sharp change. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(7): 630–638, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10117 相似文献
95.
Observations of high temperature impinging-jet boiling phenomena 总被引:1,自引:0,他引:1
Peter Lloyd Woodfield Masanori Monde Aloke Kumar Mozumder 《International Journal of Heat and Mass Transfer》2005,48(10):2032-2041
A high-speed video camera and microphone were used to capture the flow behavior and boiling sound of a free-surface water jet impinging on a high temperature surface during quench cooling. It was found that depending on the superheat of the surface considerably different flow patterns appeared. For cases where the initial surface temperature was above about 300 °C an almost explosive pattern appeared. This was in contrast to slightly lower temperatures where a liquid sheet flow structure was apparent. The change in phenomena was accompanied by a sudden change in the boiling sound and an increase in the heat transfer rate. 相似文献
96.
The time-dependent behavior of non-equilibrium condensation of moist air through a Ludwieg tube with a diaphragm downstream is investigated by using a computational fluid dynamics work. The two-dimensional, compressible, Navier-Stokes equations, fully coupled with the condensate droplet growth equations, are numerically solved by a third-order MUSCL type TVD finite-difference scheme with a second-order fractional time step. Baldwin-Lomax turbulence model is employed to close the governing equations. The present computations represent the experimental flows well. The results obtained show that for an initial relative humidity over 40 %, the periodic excursions of the condensation shock occurs in the Ludwieg tube, and the frequency increases with the initial relative humidity. It is also found that total pressure loss due to non-equilibrium condensation in the Ludwieg tube should not be ignored even for a very low initial relative humidity. Furthermore, the variations of condensation properties are also di 相似文献
97.
An analytical method using Laplace transformation has been developed for one‐dimensional heat conduction. This method succeeded in explicitly deriving the analytical solution by which the surface temperature for the first kind of boundary condition can be well predicted. The analytical solutions for the surface temperature and heat flux are applied to the second and third of the boundary conditions. These solutions are also found to estimate the corresponding surface conditions with a high degree of accuracy when the surface conditions smoothly change. On the other hand, when these conditions erratically change such as the first derivative of temperature with time, the accuracy of the estimation becomes slightly less than that for a smooth condition. This trend in the estimation is similar irrespective of any kind of boundary condition. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(1): 29–41, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10069 相似文献
98.
Koichi OkadaShigemi Kohiki Suning Luo Daiichiro SekibaSatoshi Ishii Masanori MitomeAtsushi Kohno Takayuki TajiriFumiya Shoji 《Thin solid films》2011,519(11):3557-3561
Thin films of indium tin oxide (ITO) sputter-deposited by dc-plasma containing deuterium on glass substrate without any heat treatments exhibited gradual lowering in electrical resistivity with increasing the deuterium content [D2] in plasma gas by 1% and then demonstrated a jump in resistivity by further increase of [D2] than 1%. X-ray photoelectron spectroscopy revealed that hydroxyl-bonded oxygen in ITO grew continuingly with [D2]. Deuterium positioned at the interstitial site increased almost quantitatively with increasing [D2]. Rutherford backscattering spectroscopy showed gradual reduction in the oxygen content of ITO with increasing [D2] by 1% and then demonstrated an abrupt increase of the oxygen content with the increase of [D2] than 1%. The films with [D2] < 1% were oxygen deficient, but those with [D2] > 1% were excess of oxygen. The most oxygen deficient film of [D2] = 1% was the most conductive. Behavior in the resistivity with [D2] looks parallel to that in the oxygen content. A lower resistivity of the films corresponded well to oxygen vacancy rather than hydrogen interstitial. 相似文献
99.
Photoluminescence properties from water soluble CdSe/ZnS QDs encapsulated with hybrid trioctylphosphine-poly(acrylamide-co-acrylic acid)-ethanolamine (TOPO-PSMA-EA) shell have been investigated. It was found that PL efficiency of CdSe/ZnS QDs in water was increased 5–30% after introducing PSMA-EA polymers to encapsulate CdSe/ZnS-TOPO QDs. Higher PSMA concentrations were found to enhance the PL efficiency of QDs up to 1.8 folds, which is ascribed to a better packing and passivation of the TOPO-PSMA-EA shell over the QDs. Time-resolved photoluminescence suggested that the mean lifetime of photoexcited carriers in the water-soluble CdSe/ZnS-TOPO-PSMA-EA QDs elongated 2–17 ns compared with that of uncoated samples, indicating that PL quenching defects were effectively removed for CdSe/ZnS QDs with hybrid TOPO-PSMA-EA shell. 相似文献
100.
Critical Heat Flux (CHF) is an important parameter for the thermal design of any heat generating system, most importantly, nuclear reactors. Owing to the complex mechanisms of CHF there has been a large proliferation of the correlations, each having narrow range of validity, which shows that the empirical correlation is not an appropriate approach for the CHF prediction for a wide range of validity. This limitation has led to the development of the phenomenological approach of the CHF prediction. The film dryout mechanism is applicable to the high quality CHF corresponding to the annular flow pattern in which the progressive depletion of the liquid film leads to dryout. The basic concern in the prediction of dryout is the accuracy in the evaluation of the droplet deposition and entrainment. There are various models for the estimation of the entrainment and deposition of droplets. However, most of these models are based on the air-water data at the atmospheric conditions and hence their applicability to the BWR conditions needs to be confirmed. Some of the models are based on the steam-water data which needs to be validated for the dryout prediction under BWR conditions. In this paper, the film dryout modelling has been carried out for the prediction of CHF using appropriate models for entrainment fraction and deposition coefficient. The results have been compared with the CHF data generated to substantiate the appropriateness of the selected models under BWR conditions. 相似文献