全文获取类型
收费全文 | 1446篇 |
免费 | 39篇 |
专业分类
化学 | 663篇 |
晶体学 | 10篇 |
力学 | 41篇 |
数学 | 86篇 |
物理学 | 435篇 |
无线电 | 250篇 |
出版年
2021年 | 16篇 |
2020年 | 18篇 |
2019年 | 15篇 |
2018年 | 10篇 |
2016年 | 20篇 |
2015年 | 18篇 |
2014年 | 23篇 |
2013年 | 57篇 |
2012年 | 46篇 |
2011年 | 58篇 |
2010年 | 41篇 |
2009年 | 37篇 |
2008年 | 61篇 |
2007年 | 75篇 |
2006年 | 71篇 |
2005年 | 55篇 |
2004年 | 59篇 |
2003年 | 38篇 |
2002年 | 37篇 |
2001年 | 39篇 |
2000年 | 32篇 |
1999年 | 16篇 |
1998年 | 15篇 |
1997年 | 25篇 |
1996年 | 22篇 |
1995年 | 29篇 |
1994年 | 34篇 |
1993年 | 42篇 |
1992年 | 21篇 |
1991年 | 14篇 |
1990年 | 22篇 |
1989年 | 22篇 |
1988年 | 18篇 |
1987年 | 11篇 |
1986年 | 15篇 |
1985年 | 15篇 |
1984年 | 23篇 |
1983年 | 19篇 |
1982年 | 23篇 |
1981年 | 18篇 |
1980年 | 18篇 |
1979年 | 16篇 |
1978年 | 27篇 |
1977年 | 16篇 |
1976年 | 28篇 |
1975年 | 17篇 |
1974年 | 24篇 |
1973年 | 14篇 |
1972年 | 18篇 |
1970年 | 9篇 |
排序方式: 共有1485条查询结果,搜索用时 208 毫秒
81.
Neiman A Schimansky-Geier L Moss F Shulgin B Collins JJ 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》1999,60(1):284-292
We study, in terms of synchronization, the nonlinear response of noisy bistable systems to a stochastic external signal, represented by Markovian dichotomic noise. We propose a general kinetic model which allows us to conduct a full analytical study of the nonlinear response, including the calculation of cross-correlation measures, the mean switching frequency, and synchronization regions. Theoretical results are compared with numerical simulations of a noisy overdamped bistable oscillator. We show that dichotomic noise can instantaneously synchronize the switching process of the system. We also show that synchronization is most pronounced at an optimal noise level-this effect connects this phenomenon with aperiodic stochastic resonance. Similar synchronization effects are observed for a stochastic neuron model stimulated by a stochastic spike train. 相似文献
82.
Osipov GV Collins JJ 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》1999,60(1):54-57
Here we propose mechanisms for suppressing non-steady-state motions--propagating pulses, spiral waves, spiral-wave chaos--in excitable media. Our approach is based on two points: (1) excitable media are multistable; and (2) traveling waves in excitable media can be separated into fast and slow motions, which can be considered independently. We show that weak impulses can be used to change the values of the slow variable at the front and back of a traveling wave, which leads to wave front and wave back velocities that are different from each other. This effect can destabilize the traveling wave, resulting in a transition to the rest state. 相似文献
83.
Davanloo F. Collins C.B. Agee F.J. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1998,26(5):1463-1475
The stacked Blumlein pulse generators developed at the University of Texas at Dallas consist of several triaxial Blumleins stacked in series at one end. The lines are charged in parallel and synchronously commutated with a single switching element at the other end, In this may, relatively low charging voltages are multiplied to give a higher desired voltage across an arbitrary load. Extensive characterization of the stacked Blumlein pulsers indicates that these devices are capable of producing high-power pulses with rise times and repetition rates in the range of 0.3-50 ns and 1-300 Hz, respectively, using a conventional thyratron, spark gap, or photoconductive switch. This paper presents the progress in the development and use of these novel pulsers. Recent adaptation of the design has enabled the stacked Blumlein to produce 50-70 MW nanosecond pulses with risetimes on the order of 200-300 ps into nominally matched loads. The device has a compact line geometry and is commutated by a single photoconductive switch triggered by a low power laser diode 相似文献
84.
85.
The forced magnetostriction of the linear-chain antiferromagnet CsNiCl3 has been measured from 1.6 to 20K. For the applied field parallel to the c-axis the data below the Néel temperature TN clearly show the effects of the spin-flop near 20 kG. Effects ascribed to domain realignment are observed below 5 kG for the field normal to the c-axis. In the paramagnetic phase above TN the magnetostrictive behavior conforms to a simple model in which the intrachain exchange J is a function only of the c-parameter. The resulting partial Grüneisen parameter is compared with that obtained from thermal expansion measurements. 相似文献
86.
The photoemission spectra of PtCu alloys of a number of different compositions has been measured. A new method of sample preparation by an interdiffusion technique allowed rapid measurement as a function of composition. The results are in general agreement with the coherent potential approximation to the electronic structures of alloys. 相似文献
87.
88.
89.
90.