全文获取类型
收费全文 | 617篇 |
免费 | 7篇 |
国内免费 | 10篇 |
专业分类
化学 | 251篇 |
晶体学 | 2篇 |
力学 | 20篇 |
数学 | 141篇 |
物理学 | 220篇 |
出版年
2019年 | 8篇 |
2016年 | 8篇 |
2015年 | 7篇 |
2014年 | 10篇 |
2013年 | 27篇 |
2012年 | 18篇 |
2011年 | 32篇 |
2010年 | 12篇 |
2009年 | 10篇 |
2008年 | 32篇 |
2007年 | 28篇 |
2006年 | 41篇 |
2005年 | 23篇 |
2004年 | 18篇 |
2003年 | 13篇 |
2002年 | 13篇 |
2001年 | 14篇 |
2000年 | 5篇 |
1999年 | 10篇 |
1998年 | 6篇 |
1997年 | 11篇 |
1996年 | 12篇 |
1995年 | 11篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 11篇 |
1991年 | 12篇 |
1990年 | 14篇 |
1989年 | 6篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 10篇 |
1985年 | 11篇 |
1983年 | 4篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1975年 | 8篇 |
1974年 | 11篇 |
1973年 | 7篇 |
1972年 | 5篇 |
1970年 | 4篇 |
1967年 | 8篇 |
1934年 | 4篇 |
1932年 | 5篇 |
1927年 | 4篇 |
1914年 | 3篇 |
1905年 | 5篇 |
排序方式: 共有634条查询结果,搜索用时 225 毫秒
1.
2.
3.
L R Bernstein 《The Journal of the Acoustical Society of America》1991,89(3):1306-1313
Several investigations suggest that sensitivity to changes in interaural disparities within select spectral regions may be degraded by the presence of energy at other, even remote, spectral regions. This study assessed whether similar degradations would be observed in an MLD paradigm. Detection thresholds were measured for NoSo and NoS pi. The signal, an 800-Hz tone (100-ms), was presented in continuous, broadband noise. Thresholds were also measured in the presence of a 400-Hz tone (the interferer) presented with an interaural phase disparity of 180 degrees and gated simultaneously with the signal or presented continuously. NoS pi thresholds increased by about 7 dB with the gated interferer at 80 dB SPL. Smaller increases were observed with lower levels of the interferer. Presenting the interferer continuously reduced substantially its effect. NoSo thresholds were affected only slightly by the interferer. Reversing the roles of the signal and interferer (400-Hz signal, 800-Hz interferer) led to smaller, but reliable degradations in performance. Diotic interferers had, in general, smaller effects on performance. The possible relation between the mechanisms that produce interference and those that foster an ability to segregate sources of sound is discussed. 相似文献
4.
Ashwani K. Padthe Nalin A. Chaturvedi Dennis S. Bernstein Sanjay P. Bhat Anthony M. Waas 《International Journal of Non》2008,43(4):277-291
We study a linearly damped preloaded two-bar linkage that exhibits hysteresis due to the presence of multiple attracting equilibria. The dynamics at the unstable equilibrium, through which a snap-through buckle occurs, are not linearizable due to a solution-dependent singularity. We stabilize the unstable equilibrium using two distinct non-linear controllers. The feedback-linearization controller requires knowledge of the linkage parameters, whereas the robust version of the intrinsic non-linear proportional-derivative controller requires only an upper bound on the stiffness. 相似文献
5.
We consider biased random walk on supercritical percolation clusters in ℤ2. We show that the random walk is transient and that there are two speed regimes: If the bias is large enough, the random
walk has speed zero, while if the bias is small enough, the speed of the random walk is positive.
Received: 20 November 2002 / Revised version: 17 January 2003
Published online: 15 April 2003
Research supported by Microsoft Research graduate fellowship.
Research partially supported by the DFG under grant SPP 1033.
Research partially supported by NSF grant #DMS-0104073 and by a Miller Professorship at UC Berkeley.
Mathematics Subject Classification (2000): 60K37; 60K35; 60G50
Key words or phrases: Percolation – Random walk 相似文献
6.
Serge Bernstein 《Mathematische Annalen》1926,95(1):585-594
Sans résumé 相似文献
7.
Jeff D. Kahn Nathan Linial Noam Nisan Michael E. Saks 《Journal of Theoretical Probability》1989,2(1):121-128
This article deals with random walks on arbitrary graphs. We consider the cover time of finite graphs. That is, we study the expected time needed for a random walk on a finite graph to visit every vertex at least once. We establish an upper bound ofO(n
2) for the expectation of the cover time for regular (or nearly regular) graphs. We prove a lower bound of (n logn) for the expected cover time for trees. We present examples showing all our bounds to be tight.Mike Saks was supported by NSF-DMS87-03541 and by AFOSR-0271. Jeff Kahn was supported by MCS-83-01867 and by AFOSR-0271. 相似文献
8.
9.
Mishra SR Bachmann KT Bernstein RH Blair RE Foudas C Lefmann WC Leung WC Oltman E Quintas PZ Sciulli FJ Shaevitz MH Smith WH Merritt FS Oreglia MJ Schellman H Schumm BA Borcherding F Fisk HE Lamm MJ Marsh W Merritt KW Yovanovitch DD Bodek A Budd HS Sakumoto WK 《Physical review letters》1989,63(2):132-135
10.
One important difference between the results of collinear and of full 3-D dynamical computations arises from the difference in the available volume in phase space (1-D versus 3-D) which can be termed a “dimensionality-bias”. Correction for this phase space factor allows for a more realistic estimate of reaction cross sections, branching ratios and 3-D product energy distributions from collinear calculations. 相似文献