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   884篇
  免费   22篇
  国内免费   1篇
化学   716篇
晶体学   11篇
力学   9篇
数学   30篇
物理学   141篇
  2023年   3篇
  2022年   5篇
  2021年   7篇
  2020年   5篇
  2019年   7篇
  2018年   7篇
  2017年   9篇
  2016年   13篇
  2015年   16篇
  2014年   13篇
  2013年   36篇
  2012年   30篇
  2011年   47篇
  2010年   32篇
  2009年   33篇
  2008年   73篇
  2007年   59篇
  2006年   61篇
  2005年   43篇
  2004年   56篇
  2003年   54篇
  2002年   65篇
  2001年   10篇
  2000年   16篇
  1999年   13篇
  1998年   9篇
  1997年   6篇
  1996年   15篇
  1995年   10篇
  1994年   8篇
  1993年   9篇
  1992年   6篇
  1991年   3篇
  1990年   5篇
  1989年   7篇
  1988年   6篇
  1987年   5篇
  1986年   4篇
  1985年   16篇
  1984年   17篇
  1983年   5篇
  1982年   13篇
  1981年   7篇
  1980年   6篇
  1979年   4篇
  1978年   4篇
  1977年   4篇
  1976年   8篇
  1973年   7篇
  1968年   2篇
排序方式: 共有907条查询结果,搜索用时 15 毫秒
81.
The purpose of this paper is to derive a generalization of Shimura's results concerning Fourier coefficients of Hilbert modular forms of half integral weight over total real number fields in the case of Hilbert-Maass wave forms over algebraic number fields by following the Shimura's method. Employing theta functions, we shall construct the Shimura correspondence Ψτ from Hilbert-Maass wave forms f of half integral weight over algebraic number fields to Hilbert-Maass wave forms of integral weight over algebraic number fields. We shall determine explicitly the Fourier coefficients of in terms of these f. Moreover, under some assumptions about f concerning the multiplicity one theorem with respect to Hecke operators, we shall establish an explicit connection between the square of Fourier coefficients of f and the central value of quadratic twisted L-series associated with the image of f.  相似文献   
82.
The reversible cross-catenation of two different coordination rings (Pd(II)- and Pt(II)-linked rings) has been achieved by using the labile nature of the Pd-N interaction and efficient hydrophobic contact between the rings.  相似文献   
83.
84.
Four new aromatic constituents, rhododendroketoside, (-)-sakuraresinoside, acernikol, and nikoenoside, were isolated from a Japanese folk medicine, the stem bark of Acer nikoense MAXIM. The structures of the new constituents were determined on the basis of chemical and physicochemical evidence. The principle cyclic diarylheptanoids were found to show inhibitory effects on the release of beta-hexosaminidase in RBL-2H3 cells.  相似文献   
85.
Two new friedelane-type triterpenes, salasones D and E, a new norfriedelane-type triterpene, salaquinone B, and a new polyacylated eudesmane-type sesquiterpene, salasol B, were isolated from the stems of Salacia chinensis LINN. (S. prinoides DC., Hippocrateaceae) collected in Thailand. Their stereostructures were elucidated on the basis of chemical and physicochemical evidence. Some norfriedelane-type triterpene, lignan, and catechin constituents were found to show radical scavenging activity.  相似文献   
86.
87.
88.
89.
Two-dimensional axisymmetric numerical simulation reproduced flames with repetitive extinction and ignition (FREI) in a micro flow reactor with a controlled temperature profile with a stoichiometric n-heptane/air mixture, which have been observed in the experiment. The ignition of hot flame occurred from consumption reactions of CO that was remained in the previous cycle of FREI. Between extinction and ignition locations of hot flames, several other heat release rate peaks related to cool and blue flames were observed for the first time. After the extinction of the hot flame, cool flame by the low-temperature oxidation of n-heptane appeared first and was stabilized in a low wall temperature region. In the downstream of the stable cool flame, a blue flame by the consumption reactions of cool flame products of CH2O and H2O2 appeared. After that, the hot flame ignition occurred from the remaining CO in the downstream of the blue flame. Then after the next hot flame ignition, the blue flame was swept away by the propagating hot flame. Soon before the hot flame merged with the stable cool flame, the hot flame propagation was intensified by the cool flame. After the hot flame merged with the stable cool flame, the hot flame reacted with the incoming fresh mixture of n-C7H16 and O2.  相似文献   
90.
From the methanolic extract of the aerial parts of Isodon japonicus, two new ent-kaurane diterpenes, isodonterpenes I and II, were isolated together with 10 known diterpenes. Their chemical structures were elucidated on the basis of chemical and physicochemical evidence. The absolute configuration of isodonterpene I was elucidated by Cu-Kα X-ray crystallographic analysis. Antimutagenic activities of the major diterpenes were evaluated by the Ames test. This study represents the first evaluation of the antimutagenic activities of ent-kaurane diterpenes.  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