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71.
To investigate the viscoelastic behavior of fluid dispersions under steady shear flow conditions, an apparatus for parallel superimposed oscillations has been constructed which consists of a rotating cup containing the liquid under investigation in which a torsional pendulum is immersed. By measuring the resonance frequency and bandwidth of the resonator in both liquid and in air, the frequency and steady-shear-rate-dependent complex shear modulus can be obtained. By exchange of the resonator lumps it is possible to use the instrument at four different frequencies: 85, 284, 740, and 2440 Hz while the steady shear rate can be varied from 1 to 55 s–1. After treatment of the theoretical background, design, and measuring procedure, the calibration with a number of Newtonian liquids is described and the accuracy of the instrument is discussed.Notation
a
radius of the lump
-
A
geometrical constant
-
b
inner radius of the sample holder
-
c
constant
-
C
1, C
2
apparatus constants
-
D
damping of the pendulum
-
e
x
, e
y
, e
z
Cartesian basis
-
e
r
, e
, e
z
orthonormal cylindrical basis
-
E
geometrical constant
-
E
t
, 0
E
t
,
t
relative strain tensor
-
f
function of shear rate
-
F
t
relative deformation tensor
-
G
(t)
memory function
-
G
*
complex shear modulus
-
G
Re(G
*
)
-
G
Im(G
*
)
-
h
distance between plates
-
H
*
transfer function
-
,
functional
-
i
imaginary unit: i
2= – 1
-
I
moment of inertia
-
J
exc
excitation current
-
J
0
amplitude of J
exc
-
k
* = k – ik
complex wave number
-
K
torsional constant
-
K
fourth order tensor
-
l
length of the lump
-
L
mutual inductance
-
M
dr
driving torque
-
M
liq
torque exerted by the liquid
-
0
M
liq,
liq
steady state and dynamic part of Mliq
-
n
power of the shear rate
-
p
isotropic pressure
-
Q
quality factor
-
r
radial position
-
R,R
0, R
c
Re(Z
*, Z
0
*
, Z
c
*
)
-
s
time
-
t, t
time
-
T
temperature
-
T, 0
T,
stress tensor
-
u
velocity
-
U
lock-in output
- 0
velocity
-
V
det
detector output voltage
-
V
sig, V
cr
signal and cross-talk part of V
det
-
x
Cartesian coordinate
-
X , X
0, X
c
Im(Z
*, Z
0
*
, Z
c
*
)
-
y
Cartesian coordinate
-
z
Cartesian coordinate, axial position 相似文献
72.
在液晶电视机的型式试验中经常遇到产品不符合标准要求的问题,这些问题会对用户的人身安全造成侵害。针对液晶电视机安规认证中常见的发热、防触电结构、接触电流和拔出插头放电量试验、电气间隙和爬电距离以及防火等问题,文章对标准进行深入解读并探讨相应的解决方案。 相似文献
73.
74.
75.
Large eddy simulation of fire plumes 总被引:1,自引:0,他引:1
Yi Wang Prateep Chatterjee John L. de Ris 《Proceedings of the Combustion Institute》2011,33(2):2473-2480
FireFOAM, a new fire modeling code based on the OpenFOAM platform (www.openfoam.org), is developed and applied to model a series of purely buoyant fire plumes with heat release rates from 14 to 58 kW. The calculations are compared with McCaffrey’s (1979) experiments. The simulation results demonstrate good quantitative agreement with experimental measurements, and show the scaling relations of mean temperature and velocity in the continuous flame, intermittent and plume regions. The numerical simulations are shown to be strictly conservative in energy. Predicted flame heights and entrainment rates also compare well with experimental correlations. The good agreements in all aspects examined show that the current CFD model performs well for small-scale fire plumes. Turbulent fluctuation intensities and PDF of mixture fraction are presented to gain more insights into the structure of fire plumes. 相似文献
76.
通过考虑某些不应态也可以被激发,在离散可激发介质Greenberg-Hasting模型中引入早期后去极化行为,研究了早期后去极化对螺旋波的影响.数值结果表明:在适当选择参数下,早期后去极化对螺旋波有很大影响,这些影响包括使螺旋波漫游、漂移和破碎,导致螺旋波波纹被扭曲和波臂粗细交替变化,以及导致螺旋波的周期在两个值之间交替变化,产生从稳定螺旋波到呼吸螺旋波和反螺旋波的相变等.当不应态的激发阈值很高时,早期后去极化对螺旋波没有影响.对发生上述现象作了简要的讨论.
关键词:
离散可激发介质
螺旋波
早期后去极化 相似文献
77.
火灾每年给中国带来了巨大的损失,春节期间的火灾损失更是严重.根据1999-2010年春节期间火灾统计资料,火灾四项指标数据具有时序性以及随机波动性、模糊性.运用时间序列与灰色拓扑预测方法相结合预测春节期间火灾发生规律,且预测出未来3年内的火灾发生情况.结果表明,时间序列预测模型的平均绝对误差较小,且所建立的灰色拓扑预测模型的拟合精度都达到"好"的标准.因此,采用时间序列与灰色拓扑预测模型相结合对春节火灾发生情况进行预测,其结果合理可靠,可供理论研究和消防部门做出相应的预防措施参考,以达到有效控制和预防春节火灾的目的. 相似文献
78.
《Analytical letters》2012,45(12):2072-2079
Platinum, palladium, ruthenium, rhodium, and iridum were determined in ultrabasic rock from the Great Dyke of Zimbabwe by inductively coupled plasma optical emission spectrometry. The limits of detection for these elements were less than 7 ng/g. The samples were fused at 1100°C to separate the noble metals which were enriched into a nickel sulfide button and dissolved in hydrochloric acid. The insoluble noble metals were filtered, dissolved in aqua regia in a boiling water bath, and determined by inductively coupled plasma optical emission spectrometry. This method was employed for the characterization of large quantities of ultrabasic rock from the Great Dyke of Zimbabwe. 相似文献
79.
Ji Won Jung In Ki Lee Duk Gun Choi Jin Hee Jeong Ki Man Kim Eun‐A Choi Deock Gil Oh 《ETRI Journal》2005,27(5):525-532
In this paper, we propose and present implementation results of a high‐speed turbo decoding algorithm. The latency caused by (de)interleaving and iterative decoding in a conventional maximum a posteriori turbo decoder can be dramatically reduced with the proposed design. The source of the latency reduction is from the combination of the radix‐4, center to top, parallel decoding, and early‐stop algorithms. This reduced latency enables the use of the turbo decoder as a forward error correction scheme in real‐time wireless communication services. The proposed scheme results in a slight degradation in bit error rate performance for large block sizes because the effective interleaver size in a radix‐4 implementation is reduced to half, relative to the conventional method. To prove the latency reduction, we implemented the proposed scheme on a field‐programmable gate array and compared its decoding speed with that of a conventional decoder. The results show an improvement of at least five fold for a single iteration of turbo decoding. 相似文献
80.
This paper proposes two kinds of complexity‐reduced algorithms for a low density parity check(LDPC) decoder. First, sequential decoding using a partial group is proposed. It has the same hardware complexity and requires a fewer number of iterations with little performance loss. The amount of performance loss can be determined by the designer, based on a tradeoff with the desired reduction in complexity. Second, an early detection method for reducing the computational complexity is proposed. Using a confidence criterion, some bit nodes and check node edges are detected early on during decoding. Once the edges are detected, no further iteration is required; thus early detection reduces the computational complexity. 相似文献