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111.
PDF文档与WEB网页有很大的差别,虽然其结构更复杂,但通常都有明确的标题、摘要和关键词等信息.重点研究如何利用WEB技术获取这些信息并利用它们对PDF文档中的图像进行索引,对其中的几种算法进行说明. 相似文献
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XML is a standard for the exchange of business data that is completely platform and vendor neutral. Because XML data comes in many forms, one of the most important technologies needed for XML applications is the ability to convert the data into visible renderings. This paper focuses on the rendering of XML/XSL documents into a readable and printable format by means of a platform-independent process that enables high-quality printing of the product. This paper introduces the core components in the data rendering engine, the X2P server and different levels of object abstraction. The design pattern and the complete formatting and representation of the XSL stylesheet into different types of output formats in the X2P server are also given. The results show that the X2P sever simultaneously constructs the formatting object tree and the area tree in a very efficient design that saves execution time and memory. 相似文献
114.
基于PDF-LES模型的凹腔支板火焰稳定器模拟 总被引:1,自引:0,他引:1
航空发动机加力燃烧室有进口气体温度高、速度高、湍流度大的特点,是极为典型的湍流与燃烧相互耦合的工况。大涡模拟(LES)兼具高精度与合理计算量两个特点,概率密度函数模型(PDF)适用于湍流与复杂化学反应相互耦合的问题。本文在基于PDF-LES的Aero Engine Combustor Simulation Code(AECSC)程序基础上,对凹腔支板火焰稳定器进行数值模拟。使用气相版本对有无凹腔支板结构分别进行三个速度入口条件下的甲烷湍流燃烧模拟,并用两相版本对带凹腔支板结构进行设计工况下煤油喷雾的模拟。结果表明:凹腔结构的火焰稳定性要优于无凹腔结构;凹腔支板结构对于液相燃料的控制能力较气相更强。 相似文献
115.
Hai-Wen Ge Min-Ming Zhu Yi-Liang Chen Eva Gutheil 《Flow, Turbulence and Combustion》2007,78(2):91-109
A hybrid unsteady Reynolds-averaged numerical simulation (U-RANS) and probability density function (PDF) method is developed
for turbulent non-reactive and reactive flows. The resulting modeled equations are solved by a consistent hybrid finite volume
and Lagrangian Monte-Carlo particle method. Both turbulent non-reactive and reactive flows in a rectangular channel containing
a triangular-shaped bluff-body are simulated. One-step and two-step mechanisms for propane/air combustion are used for the
reactive case. The time-averaged results are compared with both experimental data and numerical results from the literature
using large eddy simulation (LES) and steady RANS. The results of the present method are in good agreement with the experimental
data, and they improve the numerical results available in the literature. 相似文献
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Vibration energy harvesting has emerged as a promising method to harvest energy for small-scale applications. Enhancing the performance of a vibration energy harvester(VEH) incorporating nonlinear techniques, for example, the snap-through VEH with geometric non-linearity, has gained attention in recent years. A conventional snap-through VEH is a bi-stable system with a time-invariant potential function, which was investigated extensively in the past. In this work, a modified snap-through VEH wit... 相似文献
118.
A spray pyrolysis of a water solution of iron, manganese and iron nitrates is applied to prepare Zn0.5Mn0.5Fe2O4 single-phase ferrite with a spinel-type structure. The samples are characterized by means of differential scanning calorimetry, scanning and transmission electron microscopy, X-ray diffraction, infrared and 57Fe Mössbauer spectroscopy. The mass magnetization σ and the magnetic susceptibility 1/χ of the ferrites are measured as a function of temperature over the range of 78–728 K. The obtained sample contains nanoparticles with an average diameter d ∼7 nm possessing MnxZnyFe3−(x+y)O4 spinel-type structure with a uniform distribution of manganese and zinc atoms over the ferrite lattice. The Curie temperature is determined to be 375 ÷ 380 K. 相似文献
119.
许婴 《上饶师范学院学报》2001,21(1):95-97
作为信息与知识传播和积累工具的学报有必要实现网络化:(1)网络化有利于扩大高校学报的影响;(2)网络版的传播信息量巨大,形式多样;(3)网络化将改变出版技术和流程模式,提高工作效率,(4)网络化将促进学报的效率。目前学术期刊上网主要采用CAJ,HTML,PDF三种格式。 相似文献
120.
The joint scalar PDF method, as implemented in FLUENT, was used to simulate the autoignition of a jet of hydrogen in a turbulent co-flow of heated air. While the autoignition phenomenon is intermittent in the experiment, ensemble-averaged data on the effect of the flow on ignition length are available, which enables us to compare them with the steady state calculations.Results of sensitivity tests showed that the choice of chemical mechanism affects the calculation more than the mixing model and model constants. Further calculations for different initial conditions (i.e. temperature and velocity of the jet T jet and U jet and the co-flow T air and U air) have been done using a set of parameters selected after the sensitivity study. Scatter plots and conditional scalar profiles confirmed that the ignition is always initiated in lean mixture fractions. The ignition length was predicted with good accuracy for the case of U jet>U air but not so well for the case of U jet≈U air. For the equal velocity case, increasing the velocity resulted in delayed autoignition time (defined as the ignition length divided by the mean velocity), in agreement with the experimental trend. The results give credence to the use of the joint scalar PDF method for autoignition in non-premixed flows. 相似文献