全文获取类型
收费全文 | 284篇 |
免费 | 1篇 |
国内免费 | 5篇 |
专业分类
化学 | 66篇 |
力学 | 1篇 |
数学 | 39篇 |
物理学 | 184篇 |
出版年
2021年 | 1篇 |
2020年 | 3篇 |
2018年 | 8篇 |
2017年 | 9篇 |
2016年 | 22篇 |
2014年 | 2篇 |
2013年 | 39篇 |
2012年 | 7篇 |
2011年 | 6篇 |
2010年 | 6篇 |
2009年 | 3篇 |
2008年 | 6篇 |
2007年 | 4篇 |
2006年 | 12篇 |
2005年 | 6篇 |
2004年 | 9篇 |
2003年 | 5篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 7篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 9篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 10篇 |
1983年 | 10篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1976年 | 5篇 |
1975年 | 1篇 |
排序方式: 共有290条查询结果,搜索用时 15 毫秒
81.
82.
We show the existence of a high r. e. degree bounding only joins of minimal pairs and of a high2 nonbounding r. e. degree. MSC: 03D25. 相似文献
83.
Cowley AR Davis J Dilworth JR Donnelly PS Dobson R Nightingale A Peach JM Shore B Kerr D Seymour L 《Chemical communications (Cambridge, England)》2005,(7):845-847
The uptake of zinc bis(thiosemicarbazone) complexes in human cancer cells has been studied by fluorescence microscopy and the cellular distribution established, including the degree of uptake in the nucleus. 相似文献
84.
The polarization properties of vertical-cavity surface-emitting lasers (VCSELs) subject to optical feedback are studied experimentally. It is thereby demonstrated that polarization-selective optical feedback can be utilized to entirely eliminate VCSEL polarization switching over the entire device operating range. 相似文献
85.
Synchronization of three chaotic diode lasers is effected in a transmitter-mediator-receiver configuration. The transmitter laser's output is bidirectionally coupled to the mediator laser to achieve anticipating synchronization in their output intensities. The mediator laser's output is unidirectionally coupled to the receiver laser to achieve lag synchronization in their output intensities. This combination of lead and lag synchronization nullifies the time-of-flight lead-lag in synchronization between the transmitter and receiver lasers. This approach provides a means of eliminating time-of-flight delays in the synchronization of remote transmitters and receivers. 相似文献
86.
The properties of the twin-stripe injection laser are examined as functions of two parameters governing diffusion and waveguiding effects in the device. The carrier diffusion rate, as determined by the ambipolar diffusion coefficient,D, is shown to influence the current range over which lasing action is maintained. The curvature of the nonlinear portion of the light-current characteristic of the device is also changed asD is altered. It is found that the relative strengths of the guiding mechanisms acting upon the optical field further influence the characteristics of the structure. 相似文献
87.
We show that the promptly simple sets of Maass form a filter in the lattice ℰ of recursively enumerable sets. The degrees
of the promptly simple sets form a filter in the upper semilattice of r.e. degrees. This filter nontrivially splits the high
degrees (a is high ifa′=0″). The property of prompt simplicity is neither definable in ℰ nor invariant under automorphisms of ℰ. However, prompt simplicity
is easily shown to imply a property of r.e. sets which is definable in ℰ and which we have called the splitting property.
The splitting property is used to answer many questions about automorphisms of ℰ. In particular, we construct lowd-simple sets which are not automorphic, answering a question of Lerman and Soare. We produce classes invariant under automorphisms
of ℰ which nontrivially split the high degrees as well as all of the other classes of r.e. degrees defined in terms of the
jump operator. This refutes a conjecture of Soare and answers a question of H. Friedman.
During preparation of this paper, the first author was supported by the Heisenberg Programm der Deutschen Forschungsgemeinschaft,
West Germany. The second author was partially supported by NSF Grant MSC 77-04013. The third author was partially supported
by NSF Grant MSC 80-02937. 相似文献
88.
Through numerical solution of the Schrödinger equation we illustrate the influence of laser modulation upon the excitation of anN-level system irradiated by simultaneous laser pulses. We show that amplitude modulation, applied to a Gaussian statistical distribution of detunings, creates a sideband structure to the excitation-reaction profile which can enhance the excitation over that for monochromatic excitation.This work was performed under the auspices of the U.S. Energy Research and Development Administration under contract No. W-7405-Eng-48. 相似文献
89.
The ground state energy of small electron-hole drops is calculated for droplets ranging in size from 10 to 10,000 pairs. A new value for the bending energy of is derived. We also give a simple highly accurate formula for the total energy per pair. The surface energy is extracted from the total energy and found to agree well with a previous self-consistent calculation. The density at the center of the drop remains essentially constant over the entire range of N, indicating that the drop is not dramatically compressed by the surface tension. 相似文献
90.
H Shore 《The Journal of the Operational Research Society》2004,55(11):1218-1228
In a recent paper, Dekker et al developed a solution procedure for the newsboy problem with a cutoff transaction size (CTS), such that customers with orders larger than the cutoff value are satisfied in an alternative way, against additional cost. A compound Poisson demand with discrete order sizes is assumed, and a computational procedure developed to identify the optimal solution. In this paper, we discard all distributional assumptions, and, given that order size is random, only the first three moments of the arrival rate and the order size are specified. A general optimal solution is developed, using Shore's piece-wise linear approximations. For cases where a CTS exists, the derived optimal solution is extended to also identify the optimal CTS. The new solution approach requires minimal distributional information, and its merits relative to current approaches are discussed and numerically demonstrated. The new methodology, based on a ‘Calculus of moments’ combined with a distributional approximation, may be easily extended to other computationally intractable problems. 相似文献