全文获取类型
收费全文 | 103篇 |
免费 | 0篇 |
专业分类
化学 | 35篇 |
力学 | 7篇 |
数学 | 22篇 |
物理学 | 39篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2013年 | 3篇 |
2012年 | 1篇 |
2011年 | 5篇 |
2009年 | 1篇 |
2008年 | 3篇 |
2007年 | 4篇 |
2006年 | 3篇 |
2005年 | 7篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 4篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1938年 | 2篇 |
排序方式: 共有103条查询结果,搜索用时 15 毫秒
11.
12.
Gas-phase and catalytic combustion in heat-recirculating burners 总被引:5,自引:0,他引:5
Jeongmin Ahn Craig Eastwood Lars Sitzki Paul D. Ronney 《Proceedings of the Combustion Institute》2005,30(2):2463-2472
An experimental study of a spiral counterflow “Swiss roll” burner was conducted, with emphasis on the determination of extinction limits and comparison of results with and without bare-metal Pt catalyst. A wide range of Reynolds numbers (Re) were tested using propane–air mixtures. Both lean and rich extinction limits were extended with the catalyst, though rich limits were extended much further. With the catalyst, combustion could be sustained at Re as low as 1.2 with peak temperatures as low as 350 K. A heat transfer parameter characterizing the thermal performance of both gas-phase and catalytic combustion at all Re was identified. At low Re, the “lean” extinction limit was actually rich of stoichiometric, and rich-limit had equivalence ratios exceeded 40 in some cases. No corresponding behavior was observed without the catalyst. Gas-phase combustion, in general, occurred in a “flameless” mode near the burner center. With or without catalyst, for sufficiently robust conditions (high Re, near-stoichiometric) not requiring heat recirculation, a visible flame would propagate out of the center, but this flame could only be re-centered if the catalyst were present. Gas chromatography indicated that at low Re, even in extremely rich mixtures, CO and non-propane hydrocarbons did not form. For higher Re, where both gas-phase and catalytic combustion could occur, catalytic limits were slightly broader but had much lower limit temperatures. At sufficiently high Re, catalytic and gas-phase limits merged. It is concluded that combustion at low Re in heat-recirculating burners greatly benefits from catalytic combustion with the proper choice of mixtures that are different from those preferred for gas-phase combustion. In particular, the importance of providing a reducing environment for the catalyst to enhance O2 desorption, especially at low Re where heat losses are severe thus peak temperatures are low, is noted. 相似文献
13.
This article describes the construction of a natural family of conformally invariant differential operators on a four-dimensional (pseudo-)Riemannian manifold. Included in this family are the usual massless field equations for arbitrary helicity but there are many more besides. The article begins by classifying the invariant operators on flat space. This is a fairly straightforward task in representation theory best solved through the theory of Verma modules. The method generates conformally invariant operators in the curved case by means of Penrose's local twistor transport.S.E.R.C. Advanced Fellow and Flinders University Visiting Research Fellow 相似文献
14.
For a sequence of partial sums ofd-dimensional independent identically distributed random vectors a corresponding multivariate renewal process is defined componentwise. Via strong invariance together with an extreme value limit theorem for Rayleigh processes, a number of weak asymptotic results are established for thed-dimensional renewal process. Similar theorems for the estimated version of this process are also derived. These results are suggested to serve as simultaneous asymptotic testing devices for detecting changes in the multivariate setting. 相似文献
15.
16.
M.J. Corden J.D. Dowell D. Eastwood J. Garvey R.J. Homer M. Jobes I.R. Kenyon T. McMahon R.J. Vallance P.M. Watkins J.A. Wilson J. Gago M. Jung P. Sonderegger D. Treille P.L. Woodworth V. Eckardt J. Fent K.C.T.O. Sumorok 《Physics letters. [Part B]》1977,68(1):96-100
Measurements have been made of relative production cross sections of the by π±, K±, p and p? at 39.5 GeV/c incident on copper. production rates from π?, K? and p? are similar. The relative particle/anti-particle production cross sections for x>0 are , σ(K+)/σ(K?)=(0.85±0.5) and . The small p/p? cross section ratio disagrees with models of J/ψ production by gluon amalgamation. 相似文献
17.
18.
19.
Hao Xia Paul G. Tucker Simon Eastwood 《International Journal of Heat and Fluid Flow》2009,30(6):1067-1079
Hybrid large-eddy type simulations for chevron nozzle jet flows are performed at Mach 0.9 and Re = 1.03 × 106. Without using any subgrid scale model (SGS), the numerical approach applied in the present study is essentially implicit large-eddy simulation (ILES). However, a Reynolds-averaged Navier–Stokes (RANS) solution is patched into the near wall region. This makes the overall solution strategy hybrid RANS–ILES. The disparate turbulence length scales, implied by these different modeling approaches, are matched using a Hamilton–Jacobi equation. The complex geometry features of the chevron nozzles are fully meshed. With numerical fidelity in mind, high quality, hexahedral multi-block meshes of 12.5 × 106 cells are used. Despite the modest meshes, the novel RANS–ILES approach shows encouraging performance. Computed mean and second-order fluctuating quantities of the turbulent near field compare favorably with measurements. The radiated far-field sound is predicted using the Ffowcs Williams and Hawkings (FW–H) surface integral method. Encouraging agreement of the predicted far-field sound directivity and spectra with measurements is obtained. 相似文献
20.
Myron Miller Eugene Keating Delyle Eastwood Martha Schulz Hendrk 《Spectrochimica Acta Part B: Atomic Spectroscopy》1985,40(4):593-616
Enhancement of sensitive transition metal lines by a sodium matrix is measured in a 3-electrode d.c. plasma jet. Spiking with 0.43 M NaCI causes enhancement by factors of 1.85–2.92 in ionic lines and of 1.22–1.99 in atomic lines for eight of the structurally related analyte elements, but suppresses Zn I and Zn II emissions by about 25 %. Emission response to NaCI of lines within the same spectrum, or between different spectra of like ionization stage, can be simulated to 15 % and 20–25 %, respectively, by approximations linear in energy differences. For ionic lines these differences are the absolute value of the line excitation potential minus the energy of the ion state most readily pumped by Penning ionization by argon. For atomic lines it is the difference between emitting state excitation potential and the first ionization potential. Analyses of the experimental data strongly suggest that: (1) Na acts mainly to pertub radiative transfer rather than collisional redistribution processes; (2) population pumping of excited analyte states is largely driven by Penning ionization; (3) accelerated radiative cooling due to Na is manifested in a lowering of local kinetic temperature; (4) to a first-order of approximation, ambipolar diffusion, analyte-Na collisions of the second kind, and analyte ground state spin, do not influence emission line enhancement by easily ionized elements (EIE). Approximations are developed for predicting transition metal enhancements by arbitrary Na doping concentrations, and means are sketched for extending the method to other analyte group/EIE combinations. Practical implications of the work are noted. 相似文献