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   225254篇
  免费   2260篇
  国内免费   754篇
化学   125014篇
晶体学   3358篇
力学   8843篇
综合类   9篇
数学   24561篇
物理学   66483篇
  2021年   2158篇
  2020年   2327篇
  2019年   2695篇
  2018年   3650篇
  2017年   3478篇
  2016年   4858篇
  2015年   2778篇
  2014年   4371篇
  2013年   10292篇
  2012年   7681篇
  2011年   9177篇
  2010年   6620篇
  2009年   6365篇
  2008年   8622篇
  2007年   8627篇
  2006年   7929篇
  2005年   7241篇
  2004年   6352篇
  2003年   5821篇
  2002年   5651篇
  2001年   6020篇
  2000年   4732篇
  1999年   3530篇
  1998年   3048篇
  1997年   3084篇
  1996年   2866篇
  1995年   2351篇
  1994年   2454篇
  1993年   2469篇
  1992年   2628篇
  1991年   2688篇
  1990年   2587篇
  1989年   2565篇
  1988年   2489篇
  1987年   2465篇
  1986年   2384篇
  1985年   3068篇
  1984年   3228篇
  1983年   2580篇
  1982年   2855篇
  1981年   2720篇
  1980年   2521篇
  1979年   2735篇
  1978年   2849篇
  1977年   2863篇
  1976年   2845篇
  1975年   2699篇
  1974年   2680篇
  1973年   2821篇
  1972年   1885篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Galkina  E. G.  Zaspel  C. E.  Ivanov  B. A.  Kulagin  N. E.  Lerman  L. M. 《JETP Letters》2019,110(7):481-486
JETP Letters - The motion of domain walls in GdFeCo-type ferrimagnets near the point of compensation of sublattice spins s1 and s2, when the effects of the exchange increase in the limiting wall...  相似文献   
62.
Prostate cancer is a highly prevalent disease and ranks second among malignant neoplasms that affect men around the world, behind lung cancer alone. Trace elements are very important and are involved in many cellular processes. The X-ray microfluorescence technique is an advanced tool of high spatial resolution, sensitivity, multielemental analysis, and nondestructiveness for trace element study. This study aimed to investigate the elemental distribution in spheroids obtained through the following human prostate cell lines using synchrotron X-ray microfluorescence: tumor cell line androgen independent (DU145), tumor cell line androgen dependent (LNCaP), and normal cell line (RWPE-1). The measurements were performed with a standard geometry of 45° of incidence, excited by a white beam using a pixel of 25 μm and an acquisition time of 300 ms/pixel at the X-ray fluorescence beamline at the Synchrotron Light National Laboratory (Campinas, Brazil). The synchrotron X-ray microfluorescence results showed differences between groups in all elements analyzed and suggested that further studies should be performed to understand the relationship of these trace elements with the progression and development of the disease.  相似文献   
63.
Optics and Spectroscopy - Scattering of light by disordered structures is normally detrimental to their applicability in many optoelectronic devices. However, some micro and nanostructures are...  相似文献   
64.
65.
Optics and Spectroscopy - 10.1134/S0030400X17050095  相似文献   
66.
Optics and Spectroscopy - The transmission of intrinsic, antimony-doped, and gallium-doped Ge single crystals in the THz spectral range have been experimentally investigated. It is shown that the...  相似文献   
67.
68.
In this paper, the deformation of the Heisenberg algebra, consistent with both the generalized uncertainty principle and doubly special relativity, has been analyzed. It has been observed that, though this algebra can give rise to fractional derivative terms in the corresponding quantum mechanical Hamiltonian, a formal meaning can be given to them by using the theory of harmonic extensions of function. Depending on this argument, the expression of the propagator of the path integral corresponding to the deformed Heisenberg algebra, has been obtained. In particular, the consistent expression of the one dimensional free particle propagator has been evaluated explicitly. With this propagator in hand, it has been shown that, even in free particle case, normal generalized uncertainty principle and doubly special relativity show very much different result.  相似文献   
69.
The launch of the gamma-ray telescope Fermi Large Area Telescope (Fermi-LAT) started a pivotal period in indirect detection of dark matter. By outperforming expectations, for the first time a robust and stringent test of the paradigm of weakly interacting massive particles (WIMPs) is within reach. In this paper, we discuss astrophysical targets for WIMP detection and the challenges they present, review the analysis tools which have been employed to tackle these challenges, and summarize the status of constraints on and the claimed detections in the WIMP parameter space. Methods and results will be discussed in comparison to Imaging Air Cherenkov Telescopes. We also provide an outlook on short term and longer term developments.  相似文献   
70.
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