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   494268篇
  免费   3347篇
  国内免费   1065篇
化学   226116篇
晶体学   6597篇
力学   28995篇
综合类   9篇
数学   86235篇
物理学   150728篇
  2021年   3826篇
  2020年   4251篇
  2019年   5046篇
  2018年   17222篇
  2017年   17122篇
  2016年   15539篇
  2015年   5540篇
  2014年   8944篇
  2013年   17689篇
  2012年   17615篇
  2011年   26720篇
  2010年   18646篇
  2009年   19273篇
  2008年   22226篇
  2007年   24069篇
  2006年   14528篇
  2005年   13828篇
  2004年   13310篇
  2003年   12765篇
  2002年   12024篇
  2001年   11386篇
  2000年   9051篇
  1999年   6759篇
  1998年   6253篇
  1997年   6030篇
  1996年   5543篇
  1995年   5017篇
  1994年   5020篇
  1993年   4930篇
  1992年   5105篇
  1991年   5614篇
  1990年   5378篇
  1989年   5380篇
  1988年   5124篇
  1987年   5117篇
  1986年   4749篇
  1985年   5753篇
  1984年   6073篇
  1983年   5138篇
  1982年   5411篇
  1981年   5003篇
  1980年   4707篇
  1979年   5273篇
  1978年   5520篇
  1977年   5517篇
  1976年   5625篇
  1975年   5263篇
  1974年   5187篇
  1973年   5357篇
  1972年   4224篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Ukrainian Mathematical Journal - We establish new criteria of compatibility for a linear system of equations (equivalent to the Kronecker–Capelli theorem) or inequalities (equivalent to the...  相似文献   
52.
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   
53.
Physics of the Solid State - The external factors which influence the ferromagnetic resonance (FMR) line width in bilayer (ferromagnet/antiferromagnet) exchange-biased systems are studied. The...  相似文献   
54.
Atopic dermatitis is characterized by leukocyte migration into the skin dermis and typically driven by excessive chemokine production at the site of inflammation. Conventional topical formulations such as gels, creams, and ointments are insufficient for this treatment because of low penetration of drug molecules into the targeted skin tissues. Herein, using a simple, green, sustainable strategy, we have developed novel primary zein nanoparticles embedded in curcumin (Cur) and coated with silk sericin (ZHSCs) for the topical delivery of Cur to penetrate into the dermis and exercise anti-dermatitis effects on the lesion with minimal side-effects. Transdermal delivery experiments and porcine skin fluorescence imaging indicated that ZHSCs facilitate the penetration of Cur across the epidermis layer of skin to reach deep-seated sites. Notably, ZHSCs = 1:0.25 (zein-to-silk sericin mass ratios of 1:0.25) markedly elevated the skin permeability and cumulative turnover of Cur transferred, which were provided a greater than a 3.8-fold increase relative to free Cur. The special nanoparticles of ZHS = 1:0.25 possessed the deepest localization depth and experience a transition of the particle structure and core-shell separation after penetrating into the dermis of skin. In a cell model of dermatitis induced by tumor necrosis factor α/interferon γ co-stimulation, compared with free Cur, Cur-loaded ZHS nanoparticles down-regulated the generation of inflammatory cytokines and chemokines in keratinocytes through suppression of the nuclear translocation of NF-κBp65 and hence exerted an anti-dermatitis effect. This strategy may provide new avenues and direction for the demanding issues of valid topical delivery systems.  相似文献   
55.
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   
56.
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   
57.
58.
Journal of Mathematical Chemistry - The analytical solutions of an asymmetric double well potential $$V(x)=a\, x^2-b\, x^3+c\, x^4$$ are found to be a triconfluent Heun function $$H_{T}(\alpha ,...  相似文献   
59.
60.
Physics of Particles and Nuclei Letters - When creating accelerators and storage-ring installations in a compact space, there is not always enough space for all the necessary magnet elements. In...  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