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   17034篇
  免费   2815篇
  国内免费   3129篇
化学   13896篇
晶体学   288篇
力学   773篇
综合类   265篇
数学   1822篇
物理学   5934篇
  2024年   17篇
  2023年   291篇
  2022年   407篇
  2021年   571篇
  2020年   690篇
  2019年   712篇
  2018年   596篇
  2017年   594篇
  2016年   815篇
  2015年   884篇
  2014年   1103篇
  2013年   1486篇
  2012年   1582篇
  2011年   1649篇
  2010年   1263篇
  2009年   1119篇
  2008年   1307篇
  2007年   1220篇
  2006年   1058篇
  2005年   871篇
  2004年   705篇
  2003年   583篇
  2002年   537篇
  2001年   502篇
  2000年   409篇
  1999年   373篇
  1998年   256篇
  1997年   213篇
  1996年   193篇
  1995年   184篇
  1994年   155篇
  1993年   125篇
  1992年   87篇
  1991年   86篇
  1990年   82篇
  1989年   36篇
  1988年   43篇
  1987年   23篇
  1986年   39篇
  1985年   28篇
  1984年   19篇
  1983年   17篇
  1982年   9篇
  1981年   10篇
  1980年   5篇
  1979年   4篇
  1976年   3篇
  1974年   2篇
  1973年   3篇
  1957年   4篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
21.
Zhang  Liying  Li  Hao  Yang  Bingwang  Zhou  Ying  Zhang  Zhongtao  Wang  Yu 《Journal of Solid State Electrochemistry》2019,23(12):3287-3297
Journal of Solid State Electrochemistry - Co3O4 has attracted extensive interests as a non-noble-metal electrocatalyst of oxygen evolution reaction, which is critical to many electrical energy...  相似文献   
22.
The practical application of advanced personalized electronics is inseparable from flexible, durable, and even self-healable energy storage devices. However, the mechanical and self-healing performance of supercapacitors is still limited at present. Herein, highly transparent, stretchable, and self-healable poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA)/poly(vinyl alcohol) (PVA)/LiCl polyelectrolytes were facilely prepared by one-step radical polymerization. The cooperation of PAMPSA and PVA significantly increased the mechanical and self-healing capacity of the polyelectrolyte, which exhibited superior stretchability of 938 %, stress of 112.68 kPa, good electrical performance (ionic conductivity up to 20.6 mS cm−1), and high healing efficiency of 92.68 % after 24 h. After assembly with polypyrrole-coated single-walled carbon nanotubes, the resulting as-prepared supercapacitor had excellent electrochemical properties with high areal capacitance of 297 mF cm−2 at 0.5 mA cm−2 and good rate capability (218 mF cm−2 at 5 mA cm−2). Besides, after cutting in two the supercapacitor recovered 99.2 % of its original specific capacitance after healing for 24 h at room temperature. The results also showed negligible change in the interior contact resistance of the supercapacitor after ten cutting/healing cycles. The present work provides a possible solution for the development of smart and durable energy storage devices with low cost for next-generation intelligent electronics.  相似文献   
23.
24.
25.
26.
Poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP) receives increasing attention in membrane separation field based on its advantages such as high mechanical strength, thermal and chemical stability. However, controlling the microporous structure is still challenging.In this work, we attempted to tailor the morphology of PVDF-HFP membrane via a one-step reactive vapor induced phase separation method.Namely, PVDF-HFP was dissolved in a volatile solvent and then was cast in an ammonia water vapor atmosphere. After complete evaporation of solvent, membranes with adjustable porous structure were prepared, and the microstructures of the membranes were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction characterizations. Based on the results, a mechanism of dehydrofluorination induced cross-linking of PVDF-HFP has been suggested to understand the morphology tailoring.To our knowledge, this is the first report of one-step reactive vapor induced phase separation strategy to tailor morphology of PVDF-HFP membrane. In addition, the membranes prepared in the ammonia water vapor exhibited enhanced mechanical strength and achieved satisfactory separation efficiency for water-in-oil emulsions, suggesting promising potential.  相似文献   
27.
Lipid metabolism has a significant function in the central nervous system and Alzheimer's disease (AD) is an age-related senile disease characterized by central nerve degeneration. The pathological development of AD is closely related to lipid metabolism disorders. To reveal the influence of Kai-Xin-San (KXS) on lipid metabolism in APP/PSI transgenic mice and potential therapeutic targets for treating AD, brain tissue samples were collected and analyzed by high-throughput lipidomics based on UPLC–Q/TOF-MS. The collected raw data were processed by multivariate data analysis to discover the potential biomarkers and lipid metabolic profiles. Compared with the control wild-type mouse group, nine potential lipid biomarkers were found in the AD model group, of which seven were up-regulated and two were down-regulated. Orally administrated KXS can reverse the changes in these potential biomarkers. Compared with the model group, a total of six differential metabolites showed a recovery trend and may be potential targets for KXS to treat AD. This study showed that high-throughput lipidomics can be used to discover the perturbed pathways and lipid biomarkers as potential targets to reveal the therapeutic effects of KXS.  相似文献   
28.
钙钛矿/硅叠层太阳电池可以充分利用太阳光谱,提高光电转换效率.平面硅异质结太阳电池可以作为叠层电池的底电池,其性能直接影响叠层电池的性能表现.采用传统反应热蒸发技术,在低温(170 ℃)条件下制备了掺锡氧化铟薄膜,并在170 ℃的氧气氛围下后退火处理,对ITO薄膜的特性进行了详细的表征和分析.结果表明:后退火工艺改善了ITO的结晶特性,使得材料的光学特性和电学特性得到明显提高,将其应用于平面硅异质结太阳电池,短路电流密度得到极大提高,尤其红外光响应改善明显.引入MgF2薄膜作为减反射层,进一步增强了电池的光响应,转换效率达到19.04;.  相似文献   
29.
Song  Ying  Liu  Renwei  Li  Shaofan  Kang  Zhuang  Zhang  Feng 《Meccanica》2020,55(4):961-976
Meccanica - In this work, a bond-based peridynamic de-icing model has been developed to simulate the thermo-mechanical ice removal process of frozen structures. In the proposed numerical method,...  相似文献   
30.
在线社交网络已发展成为一个独特的电子生态系统,其应用深刻影响着人们生活的方方面面。由于在线社交网络特性复杂,分析在线社交网络形成和变化中的规律成为当前计算机科学、社会学和物理学的一项挑战。传统上,在线社交网络实证研究主要采用计算机辅助的被动数据获取和分析方式。近年来,在真实大规模在线社交网络上直接进行控制实验从而主动获取数据并开展分析研究的方式广受关注。评述了这一领域的研究进展,包括:社交网络控制实验的主要研究模式;控制实验方法在社交网络结构、信息传播、行为和心理学等领域取得的主要成果以及主要实验工具的适用条件和局限性。最后,展望了人工智能技术在社交网络控制实验中的应用潜力,分析了智能算法对降低实验成本和提高实验效率的作用。  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