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   15222篇
  免费   729篇
  国内免费   305篇
化学   11196篇
晶体学   143篇
力学   391篇
综合类   40篇
数学   1773篇
物理学   2713篇
  2023年   109篇
  2022年   317篇
  2021年   400篇
  2020年   351篇
  2019年   362篇
  2018年   288篇
  2017年   240篇
  2016年   509篇
  2015年   455篇
  2014年   566篇
  2013年   866篇
  2012年   1040篇
  2011年   1147篇
  2010年   700篇
  2009年   645篇
  2008年   977篇
  2007年   919篇
  2006年   875篇
  2005年   819篇
  2004年   731篇
  2003年   597篇
  2002年   549篇
  2001年   328篇
  2000年   247篇
  1999年   194篇
  1998年   139篇
  1997年   140篇
  1996年   174篇
  1995年   116篇
  1994年   122篇
  1993年   124篇
  1992年   101篇
  1991年   61篇
  1990年   67篇
  1989年   48篇
  1988年   73篇
  1987年   47篇
  1986年   50篇
  1985年   97篇
  1984年   61篇
  1983年   54篇
  1982年   68篇
  1981年   55篇
  1980年   42篇
  1979年   42篇
  1978年   50篇
  1977年   45篇
  1976年   38篇
  1975年   33篇
  1974年   35篇
排序方式: 共有10000条查询结果,搜索用时 361 毫秒
1.
2.
3.
Journal of Thermal Analysis and Calorimetry - The aim of this work is to synthesize and characterize a new structured silver–clay dried, calcined or sintered at different temperatures...  相似文献   
4.
We have synthesized a series of triarylamine‐cored molecules equipped with an adjacent amide moiety and dendritic peripheral tails in a variety of modes. We show by 1H NMR and UV/Vis spectroscopy that their supramolecular self‐assembly can be promoted in solution upon light stimulation and radical initiation. In addition, we have probed their molecular arrangements and mesomorphic properties in the bulk by integrated studies on their film state by using differential scanning calorimetry (DSC), variable‐temperature polarizing optical microscopy (VT‐POM), variable‐temperature X‐ray diffraction (VT‐XRD), and atomic force microscopy (AFM). Differences in the number and the disposition of the peripheral tails significantly affect their mesomorphic properties associated with their lamellar‐ or columnar‐packed nanostructures, which are based on segregated stacks of the triphenylamine cores and the lipophilic/lipophobic periphery. Such structural tuning is of interest for implementation of these soft self‐assemblies as electroactive materials from solution to mesophases.  相似文献   
5.
6.
Editorial 69     
Foundations of Chemistry -  相似文献   
7.
8.
Oral microbes have the capacity to spread throughout the gastrointestinal system and are strongly associated with multiple diseases. Given that tonsils are located between the oral cavity and the laryngopharynx at the gateway of the alimentary and respiratory tracts, tonsillar tissue may also be affected by microbiota from both the oral cavity (saliva) and the alimentary tract. Here, we analyzed the distribution and association of the microbial communities in the saliva and tonsils of Korean children subjected to tonsillectomy because of tonsil hyperplasia (n = 29). The microbiome profiles of saliva and tonsils were established via 16S rRNA gene sequencing. Based on the alpha diversity indices, the microbial communities of the two groups showed high similarities. According to Spearman’s ranking correlation analysis, the distribution of Treponema, the causative bacterium of periodontitis, in saliva and tonsils was found to have a significant positive correlation. Two representative microbes, Prevotella in saliva and Alloprevotella in tonsils, were negatively correlated, while Treponema 2 showed a strong positive correlation between saliva and tonsils. Taken together, strong similarities in the microbial communities of the tonsils and saliva are evident in terms of diversity and composition. The saliva microbiome is expected to significantly affect the tonsil microbiome. Furthermore, we suggest that our study creates an opportunity for tonsillar microbiome research to facilitate the development of novel microbiome-based therapeutic strategies.Subject terms: Comparative genomics, Metagenomics  相似文献   
9.
Central European Journal of Operations Research - Societal awareness and legislation changes concerning sustainability have affected how organizations generate value for stakeholders, as well as...  相似文献   
10.
Meccanica - Fiber reinforced materials are used in assorted engineering application and for this reason, new additive manufacturing technologies have been developed for this type of materials. With...  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