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   78923篇
  免费   6497篇
  国内免费   4986篇
化学   23513篇
晶体学   1809篇
力学   3517篇
综合类   343篇
数学   18013篇
物理学   43211篇
  2023年   153篇
  2021年   322篇
  2020年   620篇
  2019年   924篇
  2018年   889篇
  2017年   592篇
  2016年   445篇
  2015年   407篇
  2014年   1074篇
  2013年   1610篇
  2012年   1159篇
  2011年   1706篇
  2010年   2298篇
  2009年   6806篇
  2008年   7862篇
  2007年   6332篇
  2006年   5794篇
  2005年   3939篇
  2004年   3764篇
  2003年   3979篇
  2002年   4705篇
  2001年   3670篇
  2000年   3489篇
  1999年   3311篇
  1998年   2740篇
  1997年   1906篇
  1996年   1723篇
  1995年   2197篇
  1994年   2140篇
  1993年   1596篇
  1992年   1101篇
  1991年   833篇
  1990年   677篇
  1989年   599篇
  1988年   565篇
  1987年   402篇
  1986年   191篇
  1985年   947篇
  1984年   620篇
  1983年   487篇
  1982年   641篇
  1981年   794篇
  1980年   723篇
  1979年   561篇
  1978年   582篇
  1977年   538篇
  1976年   540篇
  1975年   317篇
  1974年   354篇
  1973年   462篇
排序方式: 共有10000条查询结果,搜索用时 219 毫秒
71.
72.
73.
74.
The first part of this article is an overview on some recent major developments in the field of analysis and partial different equations.It is a brief presentation given by the author at a round table discussion.The second part is a supplement of various details provided by several outstanding researchers on subjects.  相似文献   
75.
76.
In this paper, a reconstruction problem of the spatial dependent acoustic source from multiple frequency data is discussed. Suppose that the source function is supported on a bounded domain and the piecewise constant intensities of the source are known on the support. We characterize unknown domain by the level set technique. And the level set function can be modeled by a Hamilton-Jacobi system. We use the ensemble Kalman filter approach to analyze the system state. This method can avoid to deal with the nonlinearity directly and reduce the computation complexity. In addition, the algorithm can achieve the stable state quickly with the Hamilton-Jacobi system. From some numerical examples, we show these advantages and verify the feasibility and effectiveness.  相似文献   
77.
78.
79.
80.
《Arabian Journal of Chemistry》2020,13(11):8424-8457
Nowadays, increasing extortions regarding environmental problems and energy scarcity have stuck the development and endurance of human society. The issue of inorganic and organic pollutants that exist in water from agricultural, domestic, and industrial activities has directed the development of advanced technologies to address the challenges of water scarcity efficiently. To solve this major issue, various scientists and researchers are looking for novel and effective technologies that can efficiently remove pollutants from wastewater. Nanoscale metal oxide materials have been proposed due to their distinctive size, physical and chemical properties along with promising applications. Cupric Oxide (CuO) is one of the most commonly used benchmark photocatalysts in photodegradation owing to the fact that they are cost-effective, non-toxic, and more efficient in absorption across a significant fraction of solar spectrum. In this review, we have summarized synthetic strategies of CuO fabrication, modification methods with applications for water treatment purposes. Moreover, an elaborative discussion on feasible strategies includes; binary and ternary heterojunction formation, Z-scheme based photocatalytic system, incorporation of rare earth/transition metal ions as dopants, and carbonaceous materials serving as a support system. The mechanistic insight inferring photo-induced charge separation and transfer, the functional reactive radical species involved in a photocatalytic reaction, have been successfully featured and examined. Finally, a conclusive remark regarding current studies and unresolved challenges related to CuO are put forth for future perspectives.  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