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   751478篇
  免费   8076篇
  国内免费   2197篇
化学   390889篇
晶体学   10205篇
力学   35910篇
综合类   23篇
数学   98267篇
物理学   226457篇
  2021年   6254篇
  2020年   6919篇
  2019年   7649篇
  2018年   9856篇
  2017年   9895篇
  2016年   14436篇
  2015年   8611篇
  2014年   13702篇
  2013年   33772篇
  2012年   25879篇
  2011年   31299篇
  2010年   22347篇
  2009年   22187篇
  2008年   29256篇
  2007年   29249篇
  2006年   27147篇
  2005年   24286篇
  2004年   22412篇
  2003年   20057篇
  2002年   19895篇
  2001年   21329篇
  2000年   16488篇
  1999年   12949篇
  1998年   10976篇
  1997年   10730篇
  1996年   10330篇
  1995年   9338篇
  1994年   9141篇
  1993年   8827篇
  1992年   9549篇
  1991年   9923篇
  1990年   9436篇
  1989年   9238篇
  1988年   9271篇
  1987年   8883篇
  1986年   8497篇
  1985年   11261篇
  1984年   11664篇
  1983年   9752篇
  1982年   10369篇
  1981年   9931篇
  1980年   9464篇
  1979年   9947篇
  1978年   10198篇
  1977年   10134篇
  1976年   10050篇
  1975年   9601篇
  1974年   9371篇
  1973年   9812篇
  1972年   6667篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Optical and Quantum Electronics - Classification of hyperspectral image (HSI) is widely used for the study of remotely sensed images. Convolutional Neural Networks (CNNs) are one of the most...  相似文献   
82.
Journal of Applied Mechanics and Technical Physics - Turbulent mixing at interfaces of three-layer gas systems after shock-wave passage has been studied. The influence of the initial roughness of...  相似文献   
83.
Radiophysics and Quantum Electronics - We find self-consistent stationary distributions of the electric field and plasma density in the process of ionization self-channeling of quasielectrostatic...  相似文献   
84.
Chen  R. J.  Chen  W.  Kong  F. L. 《Analysis Mathematica》2022,48(1):19-28

Restricted testing conditions were considered recently. For the maximal operator, Hytönen, Li and Sawyer [8] first obtained parental testing condition. Later, they [9] showed that it suffices to restrict testing to doubling cubes. Chen and Lacey [3] gave a similar restricted testing condition. In our paper, we discuss a version of the latter in the multilinear setting.

  相似文献   
85.
Melnikov  A.  Aksentyev  A.  Senichev  Y. 《Physics of Atomic Nuclei》2021,84(11):1871-1873
Physics of Atomic Nuclei - We have investigated the robustness of the spin-navigator based method for manipulating the beam polarization to bend magnet installation errors. Toward that end,...  相似文献   
86.
Crystallography Reports - The orientation of grains and the special boundaries formed by them in multicrystalline silicon has been studied by electron backscattered diffraction. It is found that...  相似文献   
87.
Crystallography Reports - Some questions related to the establishment, development, and prospects of physical studies using inelastic thermal-neutron scattering are briefly reviewed. The directions...  相似文献   
88.
Theoretical and Mathematical Physics - The fractional derivative method is used to take wave dispersion into account in the wave equation when describing the propagation of gravitational soliton...  相似文献   
89.
A facile biosynthesis route was followed to prepare zinc oxide nanoparticles (ZnO NPs) using Euphorbia milii (E. milii) leaf constituents. The SEM images exhibited presence of spherical ZnO NPs and the corresponding TEM images disclosed monodisperse nature of the ZnO NPs with diameter ranges between 12 and 20 nm. The Brunauer–Emmett–Teller (BET) analysis revealed that the ZnO NPs have specific surface area of 20.46 m2/g with pore diameter of 2 nm–10 nm and pore volume of 0.908 cm3/g. The EDAX spectrum exemplified the existence of Zn and O elements and non-appearance of impurities that confirmed pristine nature of the ZnO NPs. The XRD pattern indicated crystalline peaks corresponding to hexagonal wurtzite structured ZnO with an average crystallite size of 16.11 nm. The FTIR spectrum displayed strong absorption bands at 512 and 534 cm?1 related to ZnO. The photocatalytic action of ZnO NPs exhibited noteworthy degradation of methylene blue dye under natural sunlight illumination. The maximum degradation efficiency achieved was 98.17% at an illumination period of 50 min. The reusability study proved considerable photostability of the ZnO NPs during photocatalytic experiments. These findings suggest that the E. milii leaf constituents can be utilized as suitable biological source to synthesis ZnO NPs for photocatalytic applications.  相似文献   
90.
Crystallography Reports - Methods of coherent X-ray diffraction imaging of the spatial structure of noncrystalline objects and nanocrystals (nanostructures) are considered. Particular attention is...  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