全文获取类型
收费全文 | 117篇 |
免费 | 0篇 |
专业分类
化学工业 | 8篇 |
金属工艺 | 2篇 |
机械仪表 | 2篇 |
建筑科学 | 1篇 |
能源动力 | 1篇 |
轻工业 | 1篇 |
无线电 | 2篇 |
一般工业技术 | 26篇 |
冶金工业 | 69篇 |
原子能技术 | 3篇 |
自动化技术 | 2篇 |
出版年
2011年 | 2篇 |
2010年 | 3篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 1篇 |
1983年 | 8篇 |
1982年 | 1篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 4篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有117条查询结果,搜索用时 15 毫秒
1.
A crack-tip screening analysis of cleavage fracture of steel is developed. The analysis incorporates evidence that reinitiation
of an arrested cleavage crack requires less stress intensity than cleavage initiation from a fatigue precrack. Fractographic
evidence as well as metallographic sectioning of arrested cracks have previously shown that the mechanism of rapid crack propagation
by cleavage is affected strongly by partial crack-plane deflection which leaves unbroken ligaments in its wake. The tearing
of these ligaments by dimple rupture is the dominant energy-absorbing mechanism. Earlier etch-pit experiments using an Fe-Si
alloy showed that the crack-tip stress intensity based on plastic zone size is extremely low. These observations are incorporated
into a model in which cleavage crack reinitiation is analyzed using a sharp crack that is shielded by a distribution of pinching
forces along its faces. During reloading of the arrested crack, the ligaments restrict crack-tip blunting, leading to higher
local stresses. As a result, lower stress intensities are needed for reinitiation than for initiation from a fatigue precrack. 相似文献
2.
Conditioned eyeblink responses are presumably learned in the cerebellum and relayed to motoneurons by way of the red nucleus. Projections from the red nucleus to cerebellar cortex (Larsell's lobule HVI) could be important for shaping temporally adaptive features of the conditioned response. Rabbits that had pipettes containing wheat germ agglutinated horseradish peroxidase (WGA-HRP) implanted unilaterally into HVI showed retrograde labeling of neurons within subregions of the contralateral red nucleus implicated in eyeblink conditioning by lesioning and recording studies. Retrogradely labeled neurons were also observed in the pontine nuclei, inferior olive, and spinal trigeminal nucleus pars oralis. Projections to HVI provide a possible neural substrate for implementing time-derivative computational models of learning in the cerebellum. Time-derivative models are capable of describing the timing and topography of conditioned responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
J. G. Schroth J. P. Hirth R. G. Hoagland A. R. Rosenfield 《Metallurgical and Materials Transactions A》1987,18(13):1061-1072
Special formulations of theJ integral were used to quantify the combined mode I-mode III fracture behavior of ASTM A710 Grade A steel, a tough material which displays elastic-plastic behavior at room temperature. Experimental fracture initiation loci for two heat-treated conditions were linear inJ i-Jiii space, agreeing with analytical predictions based on linear elasticity. As commonly observed in mode I fracture behavior, large tearing modulus values accompanied largeJ values for mode I and mode III components, individually as well as for totalJ values. There was a pronounced tendency toward antiplane shear flow in the modified compact tension specimens tested. This may result from the concentration of mode III shear strains in the plane of the propagating crack as predicted by slip line theory. Shear fractures with the crack propagating at inclined angles to both load line and plate free surfaces are favored energetically over pure mode I cracks even though the total surface area formed by the latter is much smaller. 相似文献
4.
William D. Rosenfield 《Journal of the American Oil Chemists' Society》1967,44(12):703-707
Although oils and oil distillates are usually dextrorotatory, some levorotations can be measured in lower boiling distillates.
Fractional distillation of a Colombia crude oil of Eocene age showed that optical rotation is maximal at an average molecular
weight of 464. The rotatory power of petroleum reflects the extent to which its composition has been transformed during geochemical
maturation. Optical rotations thus can be correlated with the degree of maturity in much the same way as can such other compositional
features as aromatic character or content of steroid-like substances, which are demonstrable in petroleums.
The optical activity of petroleum is gradually degraded by maturational influences, and a decreasing trend in rotatory power
is recognized in a comparison of oils produced from rocks of progressively greater geologic age. The optical rotation of dark
crude oils can be measured in a polarimeter of suitable photometric sensitivity. The measurements extend geochemical application
of oil polarimetry, which was restricted formerly to oil distillates and decolorized oils. 相似文献
5.
Crack extension in commercial aluminum alloys proceeds by the “ductile” or fibrous mode. The process involves the large, ~1 μm to ~10μm, Fe-, Si-, and Cu-bearing inclusions which break easily, and the growth of voids at the cracked particles. The linking-up of the voids is accomplished by the rupture of the intervening ligaments, and this is affected by the fine, ~0.01μm precipitate particles that strengthen the matrix. The ~0.1μm Cr-, Mn-, and Zr-rich intermediate particles are more resistant to cracking and may enter the process in the linking-up stage. The fracture toughness of aluminum alloys therefore depends on a) the extent of the heavily strained region ahead of the crack tip, which is a function of the yield strength arad modulus, b) the size of the ligaments which is related tof c, the volume fraction of cracked particles, and c) the work of rupturing the ligaments. An approximate analysis predicts KIc varies asf c-1/6, and this is in agreement with measurements on alloys with comparable yield strength levels. Studies in which the aging conditions are altered for the samef cshow that the toughness decreases with increasing yield strength level. This degradation in toughness is related to the localization of plastic deformation. The tendency for localization is illustrated with the help of “plane strain” tension and bend specimens whose behavior is related to the toughness. Measurements of the strain distribution on the microscale show that slip is relatively uniformly distributed in a 7000-type alloy with low inclusion and particle content when the material is in the as-quenched and overaged conditions. In contrast the distribution is highly nonuniform in the peak aged condition where slip is concentrated in widely spaced superbands involving coarse slip bands with large offsets that crack prematurely. The connection between the tendency for slip localization and the fine precipitate particles which strengthen the matrix remains to be established. In overaged alloys grain boundary ruptures occur within the superbands. The amount of intergranular failure increases with grain size and is accompanied by a loss of fracture toughness. 相似文献
6.
Jouriles Ernest N.; Brown Alan S.; Rosenfield David; McDonald Renee; Croft Kathryn; Leahy Matthew M.; Walters Scott T. 《Canadian Metallurgical Quarterly》2010,24(4):592
This study evaluated methods of enhancing college students' retention of information provided to them in a computer-delivered personalized drinking feedback intervention and whether enhanced retention reduced alcohol consumption during the two-week period following the intervention. Participants were 98 college students who reported at least one heavy drinking episode in the past two weeks. After participating in an online, personalized drinking feedback intervention, students were randomly assigned to one of three experimental conditions: 1) typical, in which they were simply sent home, 2) reading, in which they were asked to spend the next 20 minutes re-reading the feedback, and 3) recall, in which they were asked to spend the next 20 minutes writing down as much of the information from the feedback as they could remember. Two weeks following the intervention, participants completed a recall test and provided information on their alcohol use during the previous two weeks. Results indicated that participants in the reading and recall conditions retained more of the feedback information than did participants in the typical condition. In addition, participants in the reading and recall conditions reported reduced alcohol consumption in the two-week period following the intervention, compared to those in the typical condition. Information retention partially mediated the effects of the reading and recall conditions on drinking outcomes. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
Rosenfield 《Fatigue & Fracture of Engineering Materials & Structures》1998,21(5):603-610
This paper discusses the fracture prevention aspects of lifetime prediction. Initially, it is pointed out that lifetime can be determined by factors such as obsolescence and consumer rejection. Lifetime is then related to acceptable risk in order to make it compatible with advances in design philosophy for large welded structures. Accident statistics are cited and the argument made that the major opportunities for lifetime improvement are revealed by failure analysis, and are shown to lie in design and production. However, there are some structures, e.g. boilers and pressure vessels, where the construction rules are so well established that failures occur mainly because of operational errors. Based on the results of the Battelle/NBS Cost of Fracture Study, attention is focused on the effect of material–property reproducibility in driving failure probability. Little evidence could be found regarding reproducibility improvements of fatigue lifetime and brittle fracture toughness in production lots of alloys over time. 相似文献
8.
Describes a university 66-credit professional diploma sequence that includes 1 yr of internship experience for the training of school psychologists to work with bilingual/bicultural populations. Competence for working with these populations involves 3 general areas: language, cross-cultural expertise, and assessment. An integrated curriculum and faculty offers linguistics, cultural-urban studies, and bilingual education courses in addition to the core courses in professional school psychology. Bilingual students and faculty have been recruited. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
10.
M. T. Miglin J. P. Hirth A. R. Rosenfield W. A. T. Clark 《Metallurgical and Materials Transactions A》1986,17(5):791-798
The grain structure, inclusion content, and precipitate types were characterized for six heat treatments of a copper-bearing
HSLA steel. A higher austenitizing temperature combined with water-quenching resulted in an acicular ferrite microstructure,
while lower temperatures produced equiaxed ferrite or ferrite-pearlite structures. Refinement of equiaxed ferrite was observed
in material austenitized at a high enough temperature to dissolve a portion of the carbonitrides, allowing reprecipitation
during the austenite-ferrite transformation. Age-hardening precipitated body-centered cubic copper clusters; face-centered
cubic copper precipitates were observed in overaged material. 相似文献