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   399834篇
  免费   4435篇
  国内免费   1271篇
化学   213941篇
晶体学   4747篇
力学   18213篇
综合类   16篇
数学   45434篇
物理学   123189篇
  2020年   3008篇
  2019年   3294篇
  2018年   4098篇
  2017年   4108篇
  2016年   6444篇
  2015年   4293篇
  2014年   6369篇
  2013年   17189篇
  2012年   13224篇
  2011年   16350篇
  2010年   11110篇
  2009年   11032篇
  2008年   15199篇
  2007年   15452篇
  2006年   14579篇
  2005年   13364篇
  2004年   12162篇
  2003年   10882篇
  2002年   10708篇
  2001年   11611篇
  2000年   8737篇
  1999年   6523篇
  1998年   5405篇
  1997年   5477篇
  1996年   5163篇
  1995年   5022篇
  1994年   5101篇
  1993年   4663篇
  1992年   5389篇
  1991年   5408篇
  1990年   5091篇
  1989年   4986篇
  1988年   5050篇
  1987年   4947篇
  1986年   4642篇
  1985年   6482篇
  1984年   6753篇
  1983年   5562篇
  1982年   5808篇
  1981年   5656篇
  1980年   5573篇
  1979年   5559篇
  1978年   5917篇
  1977年   5850篇
  1976年   5872篇
  1975年   5523篇
  1974年   5480篇
  1973年   5697篇
  1972年   3839篇
  1971年   3018篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Physics of the Solid State - Using the X-ray diffraction and electron microscopy methods, the structure and the elemental and phase compositions of hypereutectic alloy Al86Ni2Co6Gd6 (hereinafter,...  相似文献   
2.
Physics of the Solid State - The phase transitions in the two-dimensional diluted Potts model with the number of spin states q = 3 are studied by computer simulation method. The systems...  相似文献   
3.
Journal of Analytical Chemistry - The work is dedicated to the determination of polyaromatic hydrocarbons (PAHs) in soils and bottom sediments by gas chromatography–mass spectrometry using...  相似文献   
4.
Statistical Inference for Stochastic Processes - The class of autoregressive (AR) processes is extensively used to model temporal dependence in observed time series. Such models are easily...  相似文献   
5.
Journal of Applied Spectroscopy - IR reflectance spectroscopy at 50–450 cm–1 was used to study homogeneous monocrystals of (FeIn2S3)x?(In2S3)1–x grown by the method of...  相似文献   
6.
Crystallography Reports - A geometrical and topological analysis has been performed, and self-assembly of the crystal structures of intermetallic compounds CsnMk (М = Na, K, Rb, Pt, Au, Hg,...  相似文献   
7.
Avchyan  B. R.  Ghazaryan  A. G.  Sargsyan  K. A.  Sedrakian  Kh. V. 《JETP Letters》2022,116(7):428-435
JETP Letters - We present results of numerical investigations of high-order wave mixing/harmonic generation (HWM/HHG) with many-body interaction processes derived by a strong two-frequency circular...  相似文献   
8.
Automotive proton exchange membrane fuel cell stacks need to meet manufacturer specified rated beginning-of-life (BOL) performance before being assembled into vehicles and shipped off to customers. The process of “breaking-in” of a freshly assembled stack is often referred to as “conditioning.” It has become an intensely researched area especially in automotive companies, where imminent commercialization of fuel cell electric vehicles (FCEVs) demands a short, energy- and cost-efficient, and practical conditioning protocol. Significant advances in reducing the conditioning time from 1 to 2 days to as low as 4h or less, in some cases without the use of additional inert gases such as nitrogen, and with minimal use of hydrogen, and specialized test stations will be discussed.  相似文献   
9.
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   
10.
Radiophysics and Quantum Electronics - Wind-related weather hazards remain difficult to recognize targets for weather radars. Methods that use estimates of the width of the reflected-signal...  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