全文获取类型
收费全文 | 302篇 |
免费 | 39篇 |
国内免费 | 21篇 |
专业分类
化学 | 36篇 |
晶体学 | 1篇 |
力学 | 78篇 |
综合类 | 2篇 |
物理学 | 245篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 9篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 12篇 |
2013年 | 6篇 |
2012年 | 14篇 |
2011年 | 12篇 |
2010年 | 10篇 |
2009年 | 15篇 |
2008年 | 14篇 |
2007年 | 15篇 |
2006年 | 23篇 |
2005年 | 11篇 |
2004年 | 17篇 |
2003年 | 15篇 |
2002年 | 12篇 |
2001年 | 9篇 |
2000年 | 10篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 11篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 10篇 |
1992年 | 11篇 |
1991年 | 14篇 |
1990年 | 7篇 |
1989年 | 16篇 |
1988年 | 10篇 |
1987年 | 8篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1979年 | 1篇 |
排序方式: 共有362条查询结果,搜索用时 46 毫秒
71.
为揭示置障管道内甲烷/空气预混火焰传播特性,运用高速摄影技术对甲烷/空气预混火焰的形状变化和火焰前锋的速度特性进行实验,并利用大涡模拟对管道内的流场结构进行数值分析。结果表明:置障管道内依次出现了球形火焰、指尖形火焰及“蘑菇”状火焰,且“蘑菇”状火焰出现之后,火焰开始反向传播;“蘑菇”状火焰是双涡旋结构与火焰前锋面相互作用的结果,而火焰的反向传播是由流场中出现逆流结构引起的;障碍物对火焰前锋有明显的加速作用;大涡模拟成功再现了实验中观察到的火焰形状、火焰前锋速度及流场结构,说明大涡模拟适用于置障管道内预混火焰传播特性的研究。 相似文献
72.
73.
《Ultrasonics sonochemistry》2014,21(6):2037-2043
The decreasing effect of sonoluminescence (SL) in water at high acoustic powers was investigated in relation to bubble dynamics and acoustic emission spectra. The intensity of SL was measured in the power range of 1–18 W at 83.8 kHz for open-end (free liquid surface and film-covered surface) and fixed-end boundaries of sound fields. The power dependence of the SL intensity showed a maximum and then decrease to zero for all the boundaries. Similar results were obtained for sonochemiluminescence in luminol solution. The power dependence of the SL intensity was strongly correlated with the bubble dynamics captured by high-speed photography at 64 k fps. In the low-power range where the SL intensity increases, bubble streamers were observed and the population of streaming bubbles increased with the power. At powers after SL maximum occurred, bubble clusters came into existence. Upon complete SL reduction, only bubble clusters were observed. The subharmonic in the acoustic emission spectra increased markedly in the region where bubble clusters were observed. Nonspherical oscillations of clustering bubbles may make a major contribution to the subharmonic. 相似文献
74.
This paper focuses on extracting depth information with an aperture-rotating camera. Compared with previous work, the proposed method is applicable for arbitrary rotation angle by making use of pixel registration to get pixel shift angle, and calculating the pixel shift along this angle. Besides, consumption time for shift angle is reduced by means of sampling. Compared with point-by-point method, the proposed method reduces the computation time from about 1 h to 1 min for a 15-megapixel image. Experimental results of a scene named “bottles” show that the depth value has a margin of error of 5%. Proposed method makes it possible to extract depth information with a single camera and expands the application of DSLR camera. 相似文献
75.
76.
提出了采用超快激光脉冲与光纤阵列形成的光延时、跟CCD相机相结合的方法,对门控型像增强器进行了开门时间的测量,分析了该测量方法的可行性,建立了门控型像增强器开门时间的测量系统。用该测量方法对超高速光电分幅相机中的门控型像增强器开门时间进行了测量,得到了10,20,30,50 ns档开门时间的实验图片,与所加的快高压脉冲时间12.50,18.50,28.75,48.60 ns相比较,开门时间的测量精度得到了提高,该测量方法可用于超高速光电分幅相机曝光时间的标定。 相似文献
77.
分析了影响转镜扫描相机时间分辨率的各种因素,给出了极限时间分辨率和基于相机动态摄影分辨率计算的时间分辨率的理论计算公式和结果。结合国内普遍使用的SJZ-15型转镜扫描相机,用自研设备动态像质检查仪和100ps超短脉冲激光照明两种测试方法,计算出了该相机钢转镜和铍转镜在不同转速下的实测时间分辨率值,并对数据进行了分析、比对和讨论。实测数据表明:钢转镜的转速为12×104 r/min,其最高时间分辨率约为8ns;铍转镜的实用最高转速为30×104 r/min,其最高时间分辨率约为4ns。 相似文献
78.
《Analytical letters》2012,45(10):2011-2026
Abstract In HPLC with a sodium dodecyl sulphate micellar mobile phase, a perturbation of the sodium ion equilibrium gives rise to a refractive index gradient associated to a concentration gradient. This produces a loss of sensitivity and an increase of noise at a reproducible value of the retention time when thermal lens spectrometric detection is used. Baseline perturbations as this one produced by retained components of the mobile phase can overlap with the peaks of the analytes. 相似文献
79.
闪光辐射照相及光学高速摄影图象的增强处理 总被引:3,自引:0,他引:3
本文介绍图象增强处理技术在闪光辐射照相图象及光学高速摄影图象中的应用.针对闪光图象及高速摄影图象的特点,研究了一些有效的图象增强方法,取得了很好的应用效果. 文中给出了部分应用实例. 相似文献
80.
A speckle photographic technique is used for visualizing the planar distribution of the refractive deflection angles of light
transmitted through a compressible turbulent flow. Double exposure speckle photography is applied for the statistical analysis
of such flows. Quantitative visualization of the planar distribution of the refractive deflection angles of the light transmitted
through the compressible turbulent flow is performed. Turbulent structures are visible in the patterns of the deflection angles
isolines. The 2-D correlation functions of these deflection angles are constructed and analyzed. A mathematical procedure
for solving Erbeck-Merzkirch integral transformation is described and the 3-D density correlation functions are evaluated
using 2-D correlation functions of deflection angles of the light passed through the turbulence.
Received 14 November 1999 / Accepted 3 June 2000 相似文献