首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   423篇
  免费   8篇
  国内免费   3篇
化学   254篇
力学   9篇
数学   45篇
物理学   126篇
  2016年   3篇
  2015年   5篇
  2014年   6篇
  2013年   19篇
  2012年   18篇
  2011年   11篇
  2010年   8篇
  2009年   9篇
  2008年   23篇
  2007年   23篇
  2006年   18篇
  2005年   20篇
  2004年   18篇
  2003年   11篇
  2002年   12篇
  2001年   5篇
  2000年   11篇
  1999年   14篇
  1998年   2篇
  1997年   5篇
  1996年   7篇
  1995年   12篇
  1994年   10篇
  1993年   4篇
  1992年   19篇
  1991年   10篇
  1990年   16篇
  1989年   11篇
  1988年   8篇
  1987年   2篇
  1984年   3篇
  1983年   3篇
  1982年   9篇
  1981年   2篇
  1980年   6篇
  1979年   2篇
  1978年   2篇
  1977年   6篇
  1976年   3篇
  1975年   3篇
  1974年   5篇
  1973年   3篇
  1972年   9篇
  1971年   4篇
  1969年   4篇
  1968年   4篇
  1966年   5篇
  1965年   2篇
  1880年   2篇
  1875年   2篇
排序方式: 共有434条查询结果,搜索用时 46 毫秒
101.
102.
The prediction of a novel transient mass fluctuation expected in relativistic theories of gravitation that satisfy the globally-local Mach condition (that the cosmic gravitational potential is roughly equal to the square of the speed of light) is set forth. Cosmological consequences of the Mach condition are mentioned, and an experiment that tests the prediction is discussed. The apparatus, procedure, and results of this experiment are described. The predicted effect is seen with better than order of magnitude accuracy.  相似文献   
103.
The Schuster-Blackett (S-B) conjecture, which supposes the relationshipM/J=G 1/2 /2c between the magnetic dipole moments (M) of celestial objects and their angular momenta (J), where G is the Newtonian constant of gravitation, c the speed of light, and a dimensionless constant of order unity, is examined in the context of the evolution of pulsar gyromagnetic ratios. It is demonstrated that the evolution of pulsar gyromagnetic ratios is not consistent with the strong form of the S-B conjecture where is taken to be a constant. The pulsar evidence, which shows evolution withM/J constant for individual short-period pulsars, however, does admit the validity of a weaker form of the S-B conjecture, where is allowed to take on a range of values. It is also shown that the only conventional explanation of the origin of pulsar magnetic fields that produces evolution where the gyromagnetic ratio remains constant for individual pulsars which generates magnetic fields of sufficient strength, the thermally driven Hall-field-limited battery effect, may not convincingly account for the observed behavior of pulsars. A few of the implications of the S-B conjecture and the pulsar evidence are explored.  相似文献   
104.
105.
A laboratory experiment that tests the validity of Mach's principle — the relativity and gravitational induction of inertia — and relativistic gravity in strong-field circumstances is described. It consists of looking for a stationary shift in the apparent weight of an object when a transient mass fluctuation is induced in one of its parts, that part then being subjected to a pulsed thrust. The transient mass fluctuation induced is of the order of a few tens of milligrams, and the stationary weight shift observed is several milligrams. Details of the apparatus used (capable of detecting an effect at the level of about a tenth of a milligram) are presented. Procedural protocols are laid out. The results obtained — signals some 10 to 15 times the standard error in magnitude — confirm to better than order of magnitude that the predicted effect is indeed present. The consequences of this confirmation of Mach's principle and relativistic gravity are briefly addressed. In particular, it is pointed out that in light of these results radical timelessness seems to be the correct way to understand reality and, from the practical point-of-view, it may prove possible to make traversable wormholes whenever we choose to devote sufficient resources to that end.  相似文献   
106.
The study of the hypothetical activities of arbitrarily advanced cultures, particularly in the area of space and time travel, as a means of investigating fundamental issues in physics is briefly discussed. Hawking's chronology protection conjecture as it applies to wormhole spacetimes is considered. The nature of time, especially regarding the viability of time travel, as it appears in several interpretations of quantum mechanics is investigated. A conjecture on the plausibility of theories of reality that admit relativistically invariant interactions and irreducibly stochastic processes is advanced. A transient inertial reaction effect that makes it technically feasible, fleetingly, to induce large concentrations of negative mass-energy is presented and discussed in the context of macroscopic wormhole formation. Other candidates for chronology protection are examined. It is pointed out that if the strong version of Mach's principle (the gravitational induction of mass) is correct, then wormhole formation employing negative mass-energy is impossible. But if the bare masses of elementary particles are large, finite and negative, as is suggested by a heuristic general relativistic model of elementary particles, then, using the transient effect, it is technically feasible to trigger a non-linear process that may lead to macroscopic wormhole formation. Such wormholes need not be destroyed by the Hawking protection mechanism.  相似文献   
107.
108.
109.
110.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号