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排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
王芬 《武汉理工大学学报(材料科学英文版)》2005,20(Z1)
1Introduction Harmfulbacteriaexistanywhereintheworldsuchas soil,air,water,surfacesofobjectsandourskins,etc.Thenumberofbacteriumisenormous,withmanydiffer entspecies.Theyhavethreatenedthehealthofhuman beingsseriously.Withthedevelopmentofeconomyand environme… 相似文献
83.
针对武钢热轧厂层流冷却系统能耗高,水压不稳,系统反应慢,供水泵工作效率低等缺陷,进行系统改造。提高了系统的控制精度和产品质量,节能降耗取得了明显的效果。 相似文献
84.
Tang Helen H. Y.; McNally Gavan P.; Richardson Rick 《Canadian Metallurgical Quarterly》2007,121(6):1421
The authors studied the role of gamma-aminobutyric acid (GABA) in 2 types of forgetting of fear in the developing rat. One type of forgetting studied was that observed after an intermediate retention interval (the "Kamin effect"); the other type studied was that observed after a longer interval (infantile amnesia). Rats were given pairings of an auditory conditioned stimulus with shock, and learned fear was assessed by freezing. Forgetting at an intermediate retention interval (1 hr) was not alleviated by the GABAA receptor partial inverse agonist FG7142 (0, 1, 5, or 10 mg/kg), whereas forgetting at a longer retention interval (48 hr) was alleviated. These results suggest that in the developing rat, forgetting observed at different retention intervals is mediated by different physiological mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
85.
The effect of ductile crack growth on the near tip stress field in two different specimen geometries has been investigated. For homogeneous specimens it is observed that the peak stress level increases with ductile crack growth. The effect is most pronounced up to about 1 mm of crack growth. For low and intermediate hardening there is a significant effect of specimen size on the stress level. In case of mismatch in yield stress, the simulations show that the increase in stress level in the material with the lower yield stress is of a similar magnitude as is the case for stationary cracks. In case of ductile crack growth deviation from the original crack plane occurs, the highest stresses are still found close to the interface, and not in front of the current crack tip. 相似文献
86.
J Schlipf 《Bulletin of Materials Science》1989,12(3-4):185-193
A model for propagating deformation bands is developed, based on a mechanical equation of state and on evolution equations
for the structure parameters. It is shown that, contrary to normal deformation, it is necessary to discriminate between global
parameters which depend solely on time elapsed and local parameters which are functions of the strain history. Correspondingly,
two sets of equations are presented, one describing the development of the global parameters in the course of time, the other
giving the evolution of the local state parameters in the course of deformation, i.e. as a function of strain. Measurable
quantities derived from the first set are the load serrations and the band velocity, while the second set yields the flow
stress and the strain profile of the propagating band. 相似文献
87.
The dynamics of a thin liquid film falling down a uniformly heated wall is studied. The model introduced by Kalliadasis et al. [J. Fluid Mech. 475 (2003) 377] for the same problem is revisited and its deficiencies, namely the prediction of a critical
Reynolds number with 20% error, cured. For the energy equation a high-order Galerkin projection in terms of polynomial test
functions is developed. It is shown that not only does this more refined formulation correct the critical Reynolds number,
but it also gives, with an appropriate expansion close to criticality, the long-wave theory. Bifurcation diagrams for permanent
solitary waves are constructed and compared with the solution branches obtained from different models. It is shown that, in
all cases, the long-wave theory exhibits limit points and branch multiplicity, while the other models predict the continuing
existence of solitary waves. Time-dependent computations show that the free surface and interfacial temperature approach a
train of coherent structures that resemble the infinite-domain stationary solitary pulses. 相似文献
88.
碾压混凝土穿透型诱导缝不同扩展阶段的强度指标试验研究 总被引:2,自引:0,他引:2
在不同削弱度碾压混凝土轴拉试件的穿透型诱导缝周围粘贴了应变片,得到在不同应力状态下诱导缝应变发展规律为:在加载初期,离缝端不同距离的应变发展较为均匀,数值上相差不突出;随着荷载的增加,应变开始出现不均匀发展,离缝端越远,应变变化越缓慢;当接近最大荷载的阶段,缝端应变急速发展,试件瞬间断裂。应变从均匀发展变为不均匀发展,实质上隐含了诱导缝起裂、稳定发展、失稳断裂的整个过程,针对这一试验现象,结合断裂力学理论,建立了诱导缝不同开裂阶段的远场温度应力强度指标模型。 相似文献
89.
We obtain a necessary and sufficient condition for a discrete-time nonlinear system to be locally state equivalent to the nonlinear observer form. The result looks similar to the continuous counterpart except for the fact that Ad-operation is utilized instead of ad-operation. 相似文献
90.
The stress intensity factors for a short crack partially penetrating an inclusion of arbitrary shape
Some approximate solutions for predicting the stress intensity factor of a short crack penetrating an inclusion of arbitrary
shape have been developed under mode I and mode II loading conditions. The derivation of the fundamental formula is based
on the transformation toughening theory. The transformation strains in the inclusion are induced by the crack-tip field and
remotely applied stresses, and approximately evaluated by the Eshelby equivalent inclusion theory. As validated by detailed
finite element (FE) analyses, the developed solutions have good accuracy for different inclusion shape and for a wide range
of modulus ratio between inclusion and matrix material. 相似文献