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   1098篇
  免费   22篇
  国内免费   6篇
化学   803篇
晶体学   7篇
力学   22篇
数学   44篇
物理学   250篇
  2021年   8篇
  2020年   6篇
  2019年   11篇
  2018年   8篇
  2016年   8篇
  2015年   29篇
  2014年   17篇
  2013年   43篇
  2012年   37篇
  2011年   38篇
  2010年   41篇
  2009年   25篇
  2008年   50篇
  2007年   51篇
  2006年   40篇
  2005年   44篇
  2004年   32篇
  2003年   36篇
  2002年   25篇
  2001年   28篇
  2000年   36篇
  1999年   14篇
  1998年   7篇
  1997年   12篇
  1996年   9篇
  1995年   11篇
  1994年   12篇
  1993年   8篇
  1992年   16篇
  1991年   13篇
  1990年   14篇
  1989年   29篇
  1988年   24篇
  1987年   13篇
  1986年   16篇
  1985年   37篇
  1984年   17篇
  1983年   16篇
  1982年   20篇
  1981年   29篇
  1980年   20篇
  1979年   22篇
  1978年   15篇
  1977年   23篇
  1976年   26篇
  1975年   27篇
  1974年   12篇
  1973年   9篇
  1969年   6篇
  1965年   4篇
排序方式: 共有1126条查询结果,搜索用时 15 毫秒
111.
112.
113.
Many 8-[(2-benzimidazolyl)sulfinyl]-5,6,7,8-tetrahydroquinolines were synthesized and examined for their (H+ + K+) adenosine triphosphatase ATPase-inhibitory and antisecretory activities. These sulfinyl compounds could be considered to be rigid analogues of the 2-[(2-pyridyl)methylsulfinyl]benzimidazole class of antisecretory agents. All the compounds tested were potent inhibitors of (H+ + K+)ATPase. Most of the compounds also inhibited histamine-induced gastric acid secretion in rats. Among them, 8-[(5-fluoro-2-benzimidazolyl)sulfinyl]-3-methyl-5,6,7,8-tetrahydroqu inoline (XIVm) was found to have the most potent activity. The structure-activity relationships are discussed.  相似文献   
114.
115.
116.
Hydroxymaleimide was irradiated in N2-saturated 2-propanol solutions by high-energy heavy ions over a wide range of LET values. The differential G-values of the degradation of hydroxymaleimide by irradiation with the heavier ions were lower than those of the lighter ions for the same LET value. An opposite result obtained in the air-saturated system. The degradation efficiency was 1.5 times higher, when the dose rate was 1/10 times lower. When irradiated at an LET value lower than 8 eV/nm, the G-values converged to a value less than that obtained by γ-irradiation.  相似文献   
117.
Kim MS  Scharf T  Haq MT  Nakagawa W  Herzig HP 《Optics letters》2011,36(19):3930-3932
We report on the fabrication and characterization of nanoscale solid immersion lenses (nano-SILs) with sizes down to a subwavelength range. Submicrometer-scale cylinders fabricated by electron-beam lithography are thermally reflowed to form a spherical shape. Subsequent soft lithography leads to nano-SILs on transparent substrates for optical characterization. The optical characterization is performed using a high-resolution interference microscope with illumination at 642 nm wavelength. The focal spots produced by the nano-SILs show both spot-size reduction and enhanced optical intensity, which are consistent with the immersion effect.  相似文献   
118.
This paper proposes a method of structuring public policy by incorporating reciprocal expectation analysis. The proposed method is characterized by three components: identification of the problem structure perceived by stakeholders using cognitive maps, policy structuring analysis with a value–driver matrix and a reciprocal expectation matrix, and feasibility analysis of agreements among the stakeholders. The three types of relationship among stakeholders are derived from the feasibility analysis, which are “Dosho-imu”, “Isho-imu”, and “Domu”. Three tests of feasibility to reach the agreement are then proposed: “information-sharing test”, “bargaining test”, and “reframing test”. A case study is presented, applying the method to strategic transportation planning in the Kanto region of Japan. Finally, the potential functions of the proposed method in practice are discussed.  相似文献   
119.
We have developed an optical fiber length stabilization system for the distribution of reference millimeter wave signals in a long-baseline phased-array radio telescope. The fiber length was compared with an absolute wavelength reference laser using a Michelson interferometer. We used a digital servo system including a digital phase-frequency discriminator with a wide phase dynamic range and a digital signal processor (DSP) for the digital servo system. All-digital servo system made it possible to realize a robust and precise length stabilization of a 25-km long optical fiber. PACS 42.62.Eh; 42.81.Uv; 95.55.Jz  相似文献   
120.
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