全文获取类型
收费全文 | 461篇 |
免费 | 9篇 |
国内免费 | 5篇 |
专业分类
化学 | 249篇 |
晶体学 | 9篇 |
力学 | 26篇 |
数学 | 74篇 |
物理学 | 117篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 10篇 |
2017年 | 7篇 |
2016年 | 5篇 |
2015年 | 8篇 |
2014年 | 17篇 |
2013年 | 22篇 |
2012年 | 27篇 |
2011年 | 19篇 |
2010年 | 12篇 |
2009年 | 12篇 |
2008年 | 22篇 |
2007年 | 27篇 |
2006年 | 22篇 |
2005年 | 26篇 |
2004年 | 14篇 |
2003年 | 12篇 |
2002年 | 11篇 |
2001年 | 9篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1989年 | 5篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1977年 | 8篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1971年 | 4篇 |
1937年 | 4篇 |
1934年 | 4篇 |
1933年 | 3篇 |
1931年 | 4篇 |
1929年 | 4篇 |
1928年 | 5篇 |
1927年 | 4篇 |
排序方式: 共有475条查询结果,搜索用时 93 毫秒
81.
Complex tree-like nanostructures with controlled morphology are becoming increasingly important for the development of nanoscale
devices. The position of branches on III–V semiconductor nanotrees is determined by the distribution of Au seed particles.
Here we report the dependence of the distribution of Au aerosol nanoparticles on nanowires on parameters including distance
between wires, particle size, wire length, wire diameter, III–V material and particle charge. It was observed that different
wire lengths and separation distances as well as different particle polarities have a significant effect on the resulting
particle distribution while different wire diameters, particle diameters, materials and deposition voltages do not. 相似文献
82.
Rainer Dick 《International Journal of Theoretical Physics》1997,36(9):2005-2012
I examine the potential of a pointlike particle carrying SU (N
c) charge in a gauge theory with a dilaton. The potential depends on boundary conditions imposed on the dilaton: For a dilaton
that vanishes at infinity the resulting potential is a regulatized Coulomb potential of the form (r+r
ϕ)−1, withr
ϕ, inversely proportional to the decay constant of the dilaton. Another natural constraint on the dialaton ϕ is independence
of (1/g
2) exp(ϕ/fϕ) from the gauge couplingg. This requirement yields a confining potential proportional tor. 相似文献
83.
In this paper, we give a formula for computing the number of different planat embeddings of any planar biconnected graph. The enumeration method used in deriving the formula readily gives rise to efficient algorithms for the ranking, unranking and random generation of embeddings of the given graph. We also give linear time algorithms for checking planarity and constructing any particular embedding. 相似文献
84.
85.
E. Dick 《国际流体数值方法杂志》1988,8(3):317-326
The flux-vector splitting method is applied to the convective part of the steady Navier-Stokes equations for incompressible flow. By the use of partial upwind differences in the split first-order part and central differences in the second-order part, a set of discrete equations is obtained which can be solved by vector variants of classical relaxation schemes. It is shown that accurate results can be obtained on one of the GAMM backward-facing step test problems. 相似文献
86.
87.
88.
We study the problem of multivariate integration and the construction of good lattice rules in weighted Korobov spaces with
general weights. These spaces are not necessarily tensor products of spaces of univariate functions. Sufficient conditions
for tractability and strong tractability of multivariate integration in such weighted function spaces are found. These conditions
are also necessary if the weights are such that the reproducing kernel of the weighted Korobov space is pointwise non-negative.
The existence of a lattice rule which achieves the nearly optimal convergence order is proven. A component-by-component (CBC)
algorithm that constructs good lattice rules is presented. The resulting lattice rules achieve tractability or strong tractability
error bounds and achieve nearly optimal convergence order for suitably decaying weights. We also study special weights such
as finite-order and order-dependent weights. For these special weights, the cost of the CBC algorithm is polynomial. Numerical
computations show that the lattice rules constructed by the CBC algorithm give much smaller worst-case errors than the mean
worst-case errors over all quasi-Monte Carlo rules or over all lattice rules, and generally smaller worst-case errors than
the best Korobov lattice rules in dimensions up to hundreds. Numerical results are provided to illustrate the efficiency of
CBC lattice rules and Korobov lattice rules (with suitably chosen weights), in particular for high-dimensional finance problems. 相似文献
89.
Dick Bebelaar 《Chemical physics》1974,3(2):205-216
A nanosecond laser spectrometer consisting of a 3nsec ruby/Nd PTM laser, fast detection system and high brightness analysing source is described. An analysis of the geometry considerations is given for crossed beam and collinear arrangement. The excited-state absorption spectra of naphthalene in 3MP at 85°K and 293°K from 14000 to 30000 cm?1 are given. The results provide a direct method to evaluate the quantum yields for fluorescence φf and intersystem crossing φT. Also the excited-state absorption spectra of anthracene in PMM from 16000 to 26000 cm?1 and in 3MP from 26000 to 36000 cm?1 are reported. 相似文献
90.
A spectrophotometric study of an analytically useful hafnium chelate of hematein is presented. The stoichiometry, the formation constant, the optimal pH range and the free energy of formation of the chelate are described. Beer's law is obtained in the range 3–25 μg of hafnium(IV).The red-brown chelate, of probable formula HfO[hematein]2, can be used for the colorimetric determination of hafnium in the presence of zirconium, if the molar concentrations of both metals are the same. The molar absorptivity of the hafnium chelate is 5.8·104 1 mole-1 cm-1 at 520 nm and pH 2.0 at room temperature. 相似文献