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   552107篇
  免费   7276篇
  国内免费   1842篇
化学   297323篇
晶体学   8041篇
力学   24505篇
综合类   18篇
数学   64619篇
物理学   166719篇
  2021年   4425篇
  2020年   4958篇
  2019年   5332篇
  2018年   6659篇
  2017年   6539篇
  2016年   10400篇
  2015年   6900篇
  2014年   10241篇
  2013年   25656篇
  2012年   19825篇
  2011年   24548篇
  2010年   16746篇
  2009年   16711篇
  2008年   22351篇
  2007年   22320篇
  2006年   20866篇
  2005年   18862篇
  2004年   17369篇
  2003年   15279篇
  2002年   15023篇
  2001年   16949篇
  2000年   12841篇
  1999年   10101篇
  1998年   8247篇
  1997年   8019篇
  1996年   7834篇
  1995年   7022篇
  1994年   6810篇
  1993年   6567篇
  1992年   7395篇
  1991年   7461篇
  1990年   7064篇
  1989年   6870篇
  1988年   6878篇
  1987年   6736篇
  1986年   6402篇
  1985年   8503篇
  1984年   8665篇
  1983年   6910篇
  1982年   7155篇
  1981年   7049篇
  1980年   6603篇
  1979年   7006篇
  1978年   7190篇
  1977年   7051篇
  1976年   6975篇
  1975年   6594篇
  1974年   6488篇
  1973年   6541篇
  1972年   4424篇
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
191.
192.
193.
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   
194.
195.
Davidovich  M. V. 《JETP Letters》2019,109(7):472-477

The elastic moduli of bilayer graphene nanomeshes, i.e., nanomeshes of bilayer graphene, where layers at the edges of “closed” holes are coupled to each other by a continuous network of sp2-hybridized atoms, have been calculated by ab initio methods. Structures with different configurations of holes in layers with AA, AB, and 30° stackings have been studied. It has been shown that the ultimate tensile strength of the nanomeshes under consideration is higher than that of graphene nanostructures and is comparable with the ultimate tensile strength of bilayer graphene and single-layer carbon nanotubes. A possible application of such strong nanomeshes as nanocontainers for hydrogen storage and other compressed gases has been also discussed.

  相似文献   
196.
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   
197.
Hopersky  A. N.  Nadolinsky  A. M.  Petrov  I. D. 《JETP Letters》2020,111(2):72-75
JETP Letters - The leading role of the bremsstrahlung at resonant Compton scattering of a hard X-ray photon by a multielectron atom has been theoretically predicted. This result can be important in...  相似文献   
198.
The kinetics of the O3, OH and NO3 radical reactions with diazomethane were studied in smog chamber experiments employing long-path FTIR and PTR-ToF-MS detection. The rate coefficients were determined to be k CH2NN+O3?=?(3.2?±?0.4)?×?10?17 and k CH2NN+OH?=?(1.68?±?0.12)?×?10?10 cm3 molecule?1 s?1 at 295?±?3?K and 1013?±?30 hPa, whereas the CH2NN?+?NO3 reaction was too fast to be determined in the static smog chamber experiments. Formaldehyde was the sole product observed in all the reactions. The experimental results are supported by CCSD(T*)-F12a/aug-cc-pVTZ//M062X/aug-cc-pVTZ calculations showing the reactions to proceed exclusively via addition to the carbon atom. The atmospheric fate of diazomethane is discussed.  相似文献   
199.
200.
Optics and Spectroscopy - 10.1134/S0030400X17050095  相似文献   
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