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排序方式: 共有49条查询结果,搜索用时 31 毫秒
1.
Ultrasonics has the potential to reduce the cost and environmental impact of textile processing. This work investigates the effects of ultrasonic irradiation during wool scouring on fibre surface morphologies, fibre mechanical properties, and fibre dyeing abilities. A range of ultrasonic frequencies were used in the scouring bath to examine the forms of fibre cuticle damage. It is observed that wool fibres underwent ultrasonic irradiation at a low frequency have severe modifications of the fibre surface structure. Despite some visible disruptions to the fibre scale structure however, ultrasonic irradiation has shown a negligible impact on the fibre mechanical properties, especially bending abrasion resistance which depends largely on the fibre surface conditions, and is responsible for the handle and pilling propensity of the resultant fabrics. Dyeing abilities were investigated on wool samples using commercially available acid dye and reactive dye. It is found that ultrasonically scoured wool has a quicker dye uptake in the early stage of low temperature dyeing for both acid dye and reactive dye, than the conventionally scoured wool. 相似文献
2.
The mechanical behaviour of metallic materials subjected to plastic deformation is altered with the superposition of ultrasonic vibrations. A significant effect is the reduction of flow stress or acoustic softening. This phenomenon is utilized in metal forming and other deformation based manufacturing processes. Experimental investigations on ultrasonic assisted tensile tests focus on the effect of ultrasonic vibrations along the longitudinal axis of the specimen, whereas the manufacturing processes employs in transverse directions. In the present work, transverse ultrasonic vibrations are imposed during a uniaxial tensile test using an aluminium alloy. The trend of acoustic softening due to transverse direction vibrations is similar to that along longitudinal direction. A dislocation density based constitutive model is extended to model the softening due to ultrasonic effect. The predicted results agree well with the experimental observations. 相似文献
3.
本文评述了各向同性和横向各向同性柱状分层固体声散射理论和实验研究进展 ,介绍了描述圆柱状界面薄层特性的弹簧模型 ,也讨论了该领域中有待进一步研究的一些问题。 相似文献
4.
5.
Ultrasonic wave speed measurements are widely used to infer the elastic properties of solids. In the standard method, longitudinal
and shear transducers are used separately to measure the corresponding wave speeds in a material. A new experimental method
is introduced for simultaneously measuring the longitudinal and the shear wave speeds using a single set of longitudinal or
shear transducers. The method can also be used to measure the wave speeds in situ during deformation by placing the transducers along the loading axis. The transducers are housed in a specially designed
fixture such that they are not subjected to loading. The technique is demonstrated by performing uniaxial compression experiments
on fully dense isotropic solids (where the wave speeds are not expected to change during deformation) and in polymeric foams
(where the wave speeds are affected by damage). 相似文献
6.
本文评述了各向同性和横向各向同性柱状分层固体声散射理论和实验研究进展介绍了描述圆柱状界面薄层特性的弹簧模型,也讨论了该领域中有待进一步研究的一些问题。 相似文献
7.
Shear impedance of the liquid eutectic mixture CH3NHCONH2–NH4SO3NH2 was studied in the temperature range 291.7–313.2 K by using ultrasonic shear waves in the frequency range 12–80 MHz. Ultrasonic technique allowed the determination of the real part of the complex mechanical impedance and of the complex rigidity modulus. The relaxation region was shifted towards higher frequency in comparison to the Maxwell model and was fitted by the modified BEL model. 相似文献
8.
A methodology designed to monitor thermally induced loads on continuous welded rails (CWR) is presented. The technique is
based on the use of sub-surface longitudinal ultrasonic waves (l.c.r. waves) and, by means of a daily data elaboration, allows
to obtain the value of the neutral temperature of the rail as a function of time. From such information an estimation of longitudinal
stresses, to be used as a reference, can be derived. The methodology here presented has undergone a 2 years testing period,
through the instrumentation of about 3 km of railway track. All acquired data have been remotely processed in a single control
station. 相似文献
9.
Measurements of acoustic absorption and velocity as a function of frequency and concentration in KH2PO4–K2HPO4 buffers at 4°C and pH 5-7 are reported. The dependence of the observed acoustic relaxation parameters on concentration is consistent with that to be expected from perturbation of a monomer-dimer equilibrium with an equilibrium constant [for 2H2PO
4
–
(H2PO4)2
2–] of 0.21 M–1, a bimolecular rate constant of 5×108 M–1-sec–1 and a standard volume change of –5 cm3 mole. The equilibrium constant for H2PO
4
–
+ HPO4
2–H3(PO4)2
3– is estimated to be 0.7 M–1. 相似文献
10.
H. J. Hilke 《Applied Physics A: Materials Science & Processing》1973,1(6):317-329
Summary The theory of piezoelectric transducer vibrations, which may be treated as onedimensional, is developed in detail for thin
discs vibrating in a pure thickness extensional mode. An effort has been made to obtain relations of general validity, which
include losses, and which are in a simple explicit form convenient for practical calculations. The behaviour of transducers
is discussed with special attention to their characteristics at the two fundamental frequencies, the so-called parallel and
series resonances. Several peculiarities occur when transducers are coupled to media with considerably different acoustic
impedances. These peculiarities are discussed and illustrated by numerical results for quartz and PZT 4 piezoelectric discs
radiating into water, air and liquid hydrogen. The application of the theory to different types of vibrations is briefly illustrated
for thin bars vibrating longitudinally. Short discussions are included on compound transducer systems, and on the properties
of thin discs as receivers. 相似文献