全文获取类型
收费全文 | 292篇 |
免费 | 4篇 |
国内免费 | 3篇 |
专业分类
化学 | 137篇 |
晶体学 | 1篇 |
力学 | 2篇 |
数学 | 29篇 |
物理学 | 130篇 |
出版年
2021年 | 1篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2016年 | 4篇 |
2015年 | 1篇 |
2014年 | 4篇 |
2013年 | 16篇 |
2012年 | 10篇 |
2011年 | 18篇 |
2010年 | 9篇 |
2009年 | 8篇 |
2008年 | 21篇 |
2007年 | 17篇 |
2006年 | 26篇 |
2005年 | 25篇 |
2004年 | 11篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 5篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1970年 | 2篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1942年 | 2篇 |
1935年 | 2篇 |
排序方式: 共有299条查询结果,搜索用时 15 毫秒
1.
Transport in Porous Media - Membrane filtration of feed containing multiple species of particles is a common process in the industrial setting. In this work, we propose a model for filtration of a... 相似文献
2.
We report non-equilibrium molecular dynamics simulations of rigid and non-rigid dumbbell fluids to determine the contribution of internal degrees of freedom to strain-rate-dependent shear viscosity. The model adopted for non-rigid molecules is a modification of the finitely extensible nonlinear elastic (FENE) dumbbell commonly used in kinetic theories of polymer solutions. We consider model polymer melts — that is, fluids composed of rigid dumbbells and of FENE dumbbells. We report the steady-state stress tensor and the transient stress response to an applied Couerte strain field for several strain rates. We find that the rheological properties of the rigid and FENE dumbbells are qualitatively and quantitatively similar. (The only exception to this is the zero strain rate shear viscosity.) Except at high strain rates, the average conformation of the FENE dumbbells in a Couette strain field is found to be very similar to that of FENE dumbbells in the absence of strain. The theological properties of the two dumbbell fluids are compared to those of a corresponding fluid of spheres which is shown to be the most non-Newtonian of the three fluids considered.Symbol Definition
b
dimensionless time constant relating vibration to other forms of motion
-
F
force on center of mass of dumbbell
-
F
i
force on bead i of dumbbell
-
F
force between center of masses of dumbbells and
-
F
ij
force between beads i and j
-
h
vector connecting bead to center of mass of dumbbell
-
H
dimensionless spring constant for dumbbells, in units of /
2
-
I
moment of inertia of dumbbell
-
J
general current induced by applied field
-
k
B
Boltzmann's constant
-
L
angular momentum
-
m
mass of bead, (= m/2)
-
M
mass of dumbbell, g
-
N
number of dumbbells in simulation cell
-
P
translational momentum of center of mass of dumbbell
-
P
pressure tensor
-
P
xy
xy component of pressure tensor
-
Q
separation of beads in dumbbell
-
Q
eq
equilibrium extension of FENE dumbbell and fixed extension of rigid dumbbell
-
Q
0
maximum extension of dumbbell
-
r
ij
vector connecting beads i and j
-
r
position vector of center of mass dumbbell
-
R
vector connecting centers of mass of two dumbbells
-
t
time
-
t
*
dimensionless time, in units of m/
-
T
*
dimensionless temperature, in units of /k
-
u
potential energy
-
u
velocity vector of flow field
-
u
x
x component of velocity vector
-
V
volume of simulation cell
-
X
general applied field
-
strain rate, s–1
-
*
dimensionless shear rate, in units of /m 2
-
general transport property
-
Lennard-Jones potential well depth
-
friction factor for Gaussian thermostat
-
shear viscosity, g/cms
-
*
dimensionless shear viscosity, in units of m/
2
-
*
dimensionless number density, in units of
–3
-
Lennard-Jones separation of minimum energy
-
relaxation time of a fluid
-
angular velocity of dumbbell
-
orientation angle of dumbbell 相似文献
3.
David M. Berube Christopher L. Cummings Jordan H. Frith Andrew R. Binder Robert Oldendick 《Journal of nanoparticle research》2011,13(8):3089-3099
Over the last decade social scientific researchers have examined how the public perceives risks associated with nanotechnology.
The body of literature that has emerged has been methodologically diverse. The findings have confirmed that some publics perceive
nanotechnology as riskier than others, experts feel nanotechnology is less risky than the public does, and despite risks the
public is optimistic about nanotechnology development. However, the extant literature on nanotechnology and risk suffers from
sometimes widely divergent findings and has failed to provide a detailed picture of how the public actually feels about nanotechnology
risks when compared to other risks. This study addresses the deficiencies in the literature by providing a comparative approach
to gauging nanotechnology risks. The findings show that the public does not fear nanotechnology compared to other risks. Out
of 24 risks presented to the participants, nanotechnology ranked 19th in terms of overall risk and 20th in terms of “high
risk.” 相似文献
4.
5.
Daniel G. Cummings James D. Sommers Mary L. Adamic Marcos Jimenez Jeffrey J. Giglio Kevin P. Carney Karl Grimm 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(3):923-928
A radioactive 137Cs source has been analyzed for the radioactive parent 137Cs and stable decay daughter 137Ba. The ratio of the daughter to parent atoms is used to estimate the date when Cs was purified prior to source encapsulation
(an “age” since purification). The isotopes were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) after chemical
separation. In addition, Ba was analyzed by isotope dilution ICP-MS (ID-ICP-MS). A detailed error analysis of the mass spectrometric
work has been undertaken to identify areas of improvement, as well as quantifying the effect the errors have on the “age”
determined. This paper reports an uncertainty analysis to identifying areas of improvement and alternative techniques that
may reduce the uncertainties. In particular, work on isotope dilution using ICP-MS for the “age” determination of sealed sources
is presented. The results will be compared to the original work done using external standards to calibrate the ICP-MS instrument. 相似文献
6.
MaxwellD. Cummings Jimmy Lindberg Tse‐I Lin Herman deKock Oliver Lenz Elisabet Lilja Sara Fellnder Vera Baraznenok Susanne Nystrm Magnus Nilsson Lotta Vrang Michael Edlund sa Rosenquist Bertil Samuelsson Pierre Raboisson Kenneth Simmen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2010,122(9):1552-1552
7.
Maxwell D. Cummings Jimmy Lindberg Tse‐I Lin Herman de Kock Oliver Lenz Elisabet Lilja Sara Felländer Vera Baraznenok Susanne Nyström Magnus Nilsson Lotta Vrang Michael Edlund Åsa Rosenquist Bertil Samuelsson Pierre Raboisson Kenneth Simmen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2010,122(19):3320-3320
8.
9.
10.
J. F. Reed und R. W. Cummings 《Fresenius' Journal of Analytical Chemistry》1942,123(3-4):155-156
Ohne Zusammenfassung 相似文献