全文获取类型
收费全文 | 369篇 |
免费 | 50篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 97篇 |
金属工艺 | 23篇 |
机械仪表 | 7篇 |
建筑科学 | 9篇 |
能源动力 | 4篇 |
轻工业 | 81篇 |
水利工程 | 1篇 |
无线电 | 21篇 |
一般工业技术 | 84篇 |
冶金工业 | 65篇 |
自动化技术 | 22篇 |
出版年
2024年 | 1篇 |
2022年 | 8篇 |
2021年 | 11篇 |
2020年 | 12篇 |
2019年 | 11篇 |
2018年 | 19篇 |
2017年 | 15篇 |
2016年 | 23篇 |
2015年 | 13篇 |
2014年 | 21篇 |
2013年 | 21篇 |
2012年 | 9篇 |
2011年 | 15篇 |
2010年 | 9篇 |
2009年 | 16篇 |
2008年 | 14篇 |
2007年 | 7篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 6篇 |
2000年 | 10篇 |
1999年 | 4篇 |
1998年 | 20篇 |
1997年 | 18篇 |
1996年 | 29篇 |
1995年 | 13篇 |
1994年 | 13篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1973年 | 3篇 |
1967年 | 1篇 |
排序方式: 共有419条查询结果,搜索用时 15 毫秒
71.
72.
73.
Rios R. Amantea R. Smeltzer R.K. Rothwarf A. 《Electron Devices, IEEE Transactions on》1992,39(3):581-586
Simulations of the electrical behavior of MOS-SOI devices pose a difficult numerical problem due to the floating substrate region. The numerical analysis techniques required to solve the floating region problem are discussed. Models for the carrier mobilities and lifetime variation with depth into the silicon film are introduced to fit measured SOS device data. The current-voltage characteristics of SOS transistors, including the kink, are accurately simulated and compared to measurements. The floating potential variation with applied gate and drain bias predicted by the simulation is discussed 相似文献
74.
75.
R. Rios Ph.D. Student T. Magnin D. Noel O. de Bouvier 《Metallurgical and Materials Transactions A》1995,26(4):925-939
In order to study the mechanisms involved in the stress-corrosion cracking (SCC) of Alloy 600 in primary water, the influence
of the relevance of physicochemical and metallurgical parameters was assessed: hydrogen and oxygen overpressures, microstructure,
and local chemical com-position. The obtained results show that, even if the dissolution/oxidation seems to be the first and
necessary step responsible for crack initiation and if hydrogen effects can also be involved in cracking, neither a dissolution/oxidation
model nor a hydrogen model appears sufficient to account for cracking. Moreover, fractographic examinations performed on specimens’
fracture surfaces lead to the fact that attention should be paid to a cleavagelike microcracking mechanism involving interactions
between corrosion and plasticity at the vicinity of grain boundaries. A corrosion-enhanced plasticity model is proposed to
describe the intergranular and transgranular cracking in Alloy 600. 相似文献
76.
Ivani de S. Bott Luis F. G. De Souza José C. G. Teixeira Paulo R. Rios 《Metallurgical and Materials Transactions A》2005,36(2):443-454
The production of American Petroleum Institute (API) class steels using the traditional controlled rolling route rather than
the process involving accelerated cooling necessitates a careful adjustment of steel composition associated with the optimization
of the rolling schedule for the deformation and phase transformation characteristics of these modified alloys. The current
work presents a study of two, NbCr and NbCrMo, steel systems. The microstructure obtained is correlated not only with the
resulting mechanical properties, but also with the weldability and resistance to damage in the aggressive environments to
which the materials are exposed. The evaluation of the steels was undertaken at two stages along the production route, sampling
the material as plate and as tubular product, according to the API 5L 2000 standard. Tensile testing, Charpy-V impact testing,
and hardness measurements were used to determine the mechanical properties, and microstructural characterization was performed
by optical and scanning electron microscopy. The results showed that it was possible to obtain good impact properties, for
both steels, in plate and tube formats. The Charpy-V impact energy, measured at −20 °C from 100 to 250 J corresponds to a
toughness level above that required by the API 5L 2000 standard, which specifies 68 to 101 J at 0 °C. The yield strength (YS)
to ultimate tensile strength (UTS) ratio was determined to be 0.8, the API standard establishing a maximum limit of 0.93.
Both of the alloys investigated exhibited a bainitic microstructure and were successfully processed to fabricate tubular products
by the “UOE” (bending in “U”, closing in “O,” and expanding “E”) route. with regard to weldability, the two experimental steels
exhibited a heat-affected zone (HAZ) for which toughness levels (using the temperature associated with a 100 J impact energy
as a base for comparison) were higher than those for both the base metal (BM) and the weld metal (WM) itself. In order to
perform the evaluation of the behavior of the steels in an aggressive environment, more specifically their resistance to the
deleterious effects of H2S, slow strain rate tests (SSRTs) were carried out, immersing the samples in a sodium thiosulfate solution during the tests.
Though no secondary cracking was observed in the test samples, the ductility levels measured were lower than those for the
same materials tested in air. Constant load tests were also conducted according to the standard NACE conditions. Despite the
more aggressive nature of the test solution in these cases, no samples of either steel suffered failure. 相似文献
77.
S. Ratnajeevan H. Hoole Rafael Rios S. Yoganathan 《International journal for numerical methods in engineering》1988,26(1):95-108
In field systems containing a divergenceless vector, the problem may be posed in terms of a vector potential for convenience. For the solution of the magnetic vector potential in three dimensional problems with current sources, there exist three standard variational formulations in the literature. While all these are known to give verifiable physical solutions, there is some question as to which is to be preferred. Indeed, one of them is invalid for infinite dimensional fields in that, without the finite element trial functions, it will not give unique solutions since it does not explicitly impose the divergence of the vector potential. In this paper, we look at the formulations in the light of the restrictions imposed by the finite element trial functions for tetrahedral elements and arrive at the curious result that that formulation which is totally invalid when the vector potential is unrestricted by trial functions, is in fact valid in finite element analysis and, at the same time, is the best. We further show that this formulation yields naturally non-divergent vector potential solutions, strictly as a result of the trial functions. 相似文献
78.
H. Gao W. Cao C. Fang E. R. de los Rios 《Fatigue & Fracture of Engineering Materials & Structures》1994,17(10):1213-1220
Abstract— The distribution of hydrogen in the vicinity of a crack tip was studied using SIMS (Secondary Ion Mass Spectrometry) under different ratios of I/II mixed mode loads. Modified WOL specimens with kinked slits were employed in the course of the experimental work. Spectrographic measurements show that under I/II mixed mode loading, both in the HIC and in the r max p directions, there are two hydrogen accumulation peaks ahead of the crack tip, corresponding to the location of the maximum hydrostatic stress and maximum equivalent plastic strain, respectively. Based on results obtained over a range of loading conditions from mode I to a high KII / KI , ratio, it is shown that the mode II component has a clear influence on both peaks. The conditions for hydrogen redistribution are discussed in terms of crack tip stress-strain fields. 相似文献
79.
HM Kantarjian SM O'Brien M Keating M Beran E Estey S Giralt S Kornblau MB Rios D de Vos M Talpaz 《Canadian Metallurgical Quarterly》1997,11(10):1617-1620
The aim of the study was to evaluate the activity of decitabine, a hypomethylating agent, in the treatment of patients with chronic myelogenous leukemia (CML) in transformation. Thirty-seven patients with CML in blastic (20 patients) or accelerated phases (17 patients) were treated. Their median age was 52 years; 36 had Philadelphia chromosome-positive disease. Decitabine was given at 100 mg/m2 over 6 h every 12 h x 10 doses (1000 mg/m2) to 13 patients, and at 75 mg/m2 over 6 h every 12 h x 10 doses (750 mg/m2) to 24 patients. In blastic phase, two patients (10%) achieved a complete hematologic response (one with Ph suppression), and three (15%) had a hematologic improvement (marrow CR, platelets <100 x 10[3]/microl), for an overall response rate of 25%. In accelerated phase, six patients (35%) returned to a second chronic phase (two with Ph suppression), one (6%) had a hematologic improvement, and two (12%) had a partial hematologic response, for an overall response rate of 53%. Prolonged myelosuppression was the most significant side-effect. The median time to recovery of granulocytes above 500/microl was 48 days, and to recovery of platelets above 30 x 10(3)/microl, 31 days. Febrile episodes occurred in 25 patients (68%) including documented infections in 17 patients (46%). Decitabine has promising activity in CML. The most significant side-effect is prolonged myelosuppression. Decitabine may show activity in other myeloid disorders such as acute myeloid leukemia and myelodysplastic syndrome, as well as in other hematologic malignancies, alone or with other drug combinations. Its value in the context of stem cell support should also be investigated. 相似文献
80.
A. A. Rakitsky E. R. de los Rios K. J. Miller 《Fatigue & Fracture of Engineering Materials & Structures》1994,17(5):563-570
Abstract— The fatigue behaviour of a Ni-Cr-base powder flame-spray coating on a 0.4% C steel is investigated. Fatigue tests were carried out using mild hour-glass profile specimens. Cracks were detected and measured using plastic replicas and an image analysis system. Coated specimens showed a slightly lower fatigue endurance than plain specimens under torsion loading, while the opposite was observed for push-pull loading. Microcracks in coated specimens invariably form at pores.
Contrary to the usual case of stage I shear growth for a plain 0.4% C steel in tension or torsion loading, the coated specimens show initial crack growth from pores along directions perpendicular to the maximum tensile stress. The crucial behaviour of short cracks, and their growth rates, relative to the thickness of the coating, are discussed in some detail. 相似文献
Contrary to the usual case of stage I shear growth for a plain 0.4% C steel in tension or torsion loading, the coated specimens show initial crack growth from pores along directions perpendicular to the maximum tensile stress. The crucial behaviour of short cracks, and their growth rates, relative to the thickness of the coating, are discussed in some detail. 相似文献