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231.
D. Sidoti S. Xhurxhi T. Kujofsa S. Cheruku J. Reed B. Bertoli P. B. Rago E. N. Suarez F. C. Jain J. E. Ayers 《Journal of Electronic Materials》2010,39(8):1140-1145
Exponentially graded semiconductor layers are of interest for use as buffers in heteroepitaxial devices because of their tapered dislocation density and strain profiles. Here we have calculated the critical layer thickness for the onset of lattice relaxation in exponentially graded In x Ga1?x As/GaAs (001) heteroepitaxial layers. Upwardly convex grading with \( x = x_{\infty } \left( {1 - {\rm e}^{ - \gamma /y} } \right) \) was considered, where y is the distance from the GaAs interface, γ is a grading length constant, and x ∞ is the limiting mole fraction of In. For these structures the critical layer thickness was determined by an energy-minimization approach and also by consideration of force balance on grown-in dislocations. The force balance calculations underestimate the critical layer thickness unless one accounts for the fact that the first misfit dislocations are introduced at a finite distance above the interface. The critical layer thickness determined by energy minimization, or by a detailed force balance model, is approximately \( h_{\rm{c}} \approx <Exponentially graded semiconductor layers are of interest for use as buffers in heteroepitaxial devices because of their tapered
dislocation density and strain profiles. Here we have calculated the critical layer thickness for the onset of lattice relaxation
in exponentially graded In
x
Ga1−x
As/GaAs (001) heteroepitaxial layers. Upwardly convex grading with x = x¥ ( 1 - e - g/y ) x = x_{\infty } \left( {1 - {\rm e}^{ - \gamma /y} } \right) was considered, where y is the distance from the GaAs interface, γ is a grading length constant, and x
∞ is the limiting mole fraction of In. For these structures the critical layer thickness was determined by an energy-minimization
approach and also by consideration of force balance on grown-in dislocations. The force balance calculations underestimate
the critical layer thickness unless one accounts for the fact that the first misfit dislocations are introduced at a finite
distance above the interface. The critical layer thickness determined by energy minimization, or by a detailed force balance
model, is approximately hc ? < h_{\rm{c}} \approx < Although these results were developed for exponentially graded In
x
Ga1−x
As/GaAs (001), they may be generalized to other material systems for application to the design of exponentially graded buffer
layers in metamorphic device structures such as modulation-doped field-effect transistors and light-emitting diodes. 相似文献
232.
A Simple Conceptual Model of Sediment Yield 总被引:2,自引:0,他引:2
Pradeep Kumar Bhunya S. K. Jain P. K. Singh S. K. Mishra 《Water Resources Management》2010,24(8):1697-1716
The sediment graphs (time distribution of sediment yield) are very essential if the sediment transports the pollutants that
are toxic at high concentrations, requiring determination of peak, rather than average sediment flow rate. In this paper,
an effort has been made to develop a simple conceptual model of sediment yield based on Soil Conservation Service Curve Number
(SCS-CN) method, instantaneous unit sediment graph (IUSG) method, and Power law and the performance is tested using real field
data of Chaukhutia watershed of Ramganga river catchment (area = 452.25 km2). The proposed model is found to provide realistic estimates of temporal variation of sediment yield as well as total sediment
yield during a storm event. The model is found to be most sensitive to parameter β followed by k,
\upalpha\upalpha, A, and ns. A comparison is made with the existing IUSG based models of Kumar and Rastogi (J Hydrol 95:155–163, 1987) and Raghuwanshi et al. (J Hydraul Eng ASCE 120(4):495–503, 1994) for developing sediment graphs. 相似文献
233.
Additively manufactured polymeric products for automotive, aerospace, and biomedical applications are usually intended for service in an outdoor environment with high mechanical loading conditions. The strength and sustainability of the products can be significantly degraded due to the outdoor environmental conditions such as UV light, moisture, heat, and so forth. In this research work, a novel weather-resistant polymer (WRP) material, that is, acrylonitrile styrene acrylate (ASA), has been studied. Furthermore, this work aims to study the effect of process parameters and enhance the strength of WRP (ASA) specimens using the FFF process. The optimized process parameters, that is, build orientation (BO), extrusion temperature (ET), layer thickness (LT), and printing speed (PS), were identified based on the tensile and flexural strength using the Taguchi technique and statistical analysis. The best tensile and flexural strengths for the specimen were achieved at both orientations (XYZ and ZXY) TS: 255°C ET, 0.14 mm LT, 50 mm/s PS; and FS: 245°C ET, 0.28 mm LT, 50 mm/s PS, respectively. Regression model was developed to investigate the correlation between the process parameters with tensile and flexural strength. A validation test confirmed the findings, and the error between the actual and predicted values is less than ±10%. 相似文献
234.
Silicon - In this article, a Heterogeneous Gate-Dielectric Nanosheet Tunnel Field Effect Transistor (HD-NSH-TFET) with three channels is investigated using the 3-D Visual TCAD simulator. The HD... 相似文献
235.
236.
Knowledge of the business domain (e.g., insurance claim, human resources) is crucial to analysts’ ability to conduct good requirements analysis (RA). However, current practices afford little assistance to analysts in acquiring domain knowledge. We argue that traditional reuse repositories could be augmented by adding rich faceted information on component/services and artifacts such as business-process templates to help analysts acquire domain knowledge during RA. In this paper, we present the design of a Knowledge Based Component Repository (KBCR) for facilitating RA. Then, we report on the design and development of a KBCR prototype. We illustrate its application in a system that is populated with components and process templates for the auto insurance claim domain. An empirical study was conducted to assess its effectiveness in improving RA. Results showed that KBCR enhanced analysts’ business domain knowledge and helped them better prepare for RA. Our key research contribution is to offer analysts a rich repository (i.e., KBCR) containing domain knowledge that they could utilize to acquire domain knowledge that is crucial for carrying out RA. While repositories of reusable components have been employed for some time, no one has used such repositories to help analysts acquire domain knowledge in order improve the RA of the system. 相似文献
237.
Advances in design and application of neural networks 总被引:1,自引:1,他引:0
Lakhmi C. Jain 《Neural computing & applications》2010,19(2):167-168
238.
The effects of Bi4Ti3O12 addition on the microstructure and dielectric properties of Mn-modified BaTiO3 were investigated to develop low temperature fired BaTiO3-based ceramics with stable temperature characteristics. The sintering temperature of Mn-doped BaTiO3 could be reduced to 1200 °C by adding more than 1 mol% Bi4Ti3O12. TEM results show an apparent core–shell structure with 2 mol% Bi4Ti3O12 addition. However, it was destroyed when the Bi4Ti3O12 content increased from 2 to 4 mol%. The permittivity decreased and the Curie temperature shifted to higher temperature when the Bi4Ti3O12 content increased from 0 to 3 mol%. The temperature characteristic of capacitance was very close to the EIA X8R specification when 2 mol% Bi4Ti3O12 was added due to the presence of the core–shell grain structure and raised Curie temperature. With adequate Bi4Ti3O12 addition, the BaTiO3-based system shows great potential for applications in EIA X8R-type multilayer ceramic capacitors. 相似文献
239.
F. C. Jain B. Miller E. Suarez P.-Y. Chan S. Karmakar F. Al-Amoody M. Gogna J. Chandy E. Heller 《Journal of Electronic Materials》2011,40(8):1717-1726
This paper presents the implementation of a novel InGaAs field-effect transistor (FET), using a ZnSe-ZnS-ZnMgS-ZnS stacked
gate insulator, in a spatial wavefunction-switched (SWS) structural configuration. Unlike conventional FETs, SWS devices comprise
two or more asymmetric coupled quantum wells (QWs). This feature enables carrier transfer vertically from one quantum well
to another or laterally to the wells of adjacent SWS-FET devices by manipulation of the gate voltages (V
g). Observation of an extra peak (near both accumulation and inversion regions) in the capacitance–voltage data in an InGaAs-AlInAs
two-quantum-well SWS structure is presented as evidence of spatial switching. The peaks are attributed to the appearance of
carriers first in the lower well and subsequently their transfer to the upper well as the gate voltage is increased. The electrical
characteristics of a fabricated SWS InGaAs FET are also presented along with simulations of capacitance–voltage (C–V) behavior, showing the effect of wavefunction switching between wells. Finally, logic operations involving simultaneous processing
of multiple bits in a device, using coded spatial location of carriers in quantum well channels, are also described. 相似文献
240.
The present work describes a theoretical investigation into the effect of surface roughness on the stability margin of an orifice-compensated, hole-entry hybrid journal bearing system. A modified form of the average Reynolds equation is used for the solution of a lubricant flow field in the clearance space of a rough journal bearing system. The effects of surface roughness parameter (Λ), variance ratio (V?rj), and the surface orientations (γ) on the bearing flow, load-carrying capacity, and stability threshold speed margin are studied. The study indicates that the bearing configurations having surface roughness on one of the opposing surfaces (stationary or moving roughness) show an opposite trend between stability threshold speed margin and load-carrying capacity. However, the bearing configurations having transverse- and isotropic-type roughness patterns on both bearing and journal surfaces provide an improved value of both stability threshold speed margin and load-carrying capacity only when the surface roughness has a variance ratio value between 0.49 and 0.59 for the transverse roughness pattern and between 0.59 and 0.84 for the isotropic roughness pattern. 相似文献