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   325篇
  免费   7篇
  国内免费   1篇
化学   267篇
晶体学   6篇
力学   2篇
数学   19篇
物理学   39篇
  2022年   2篇
  2021年   3篇
  2020年   5篇
  2019年   12篇
  2018年   10篇
  2017年   8篇
  2016年   3篇
  2015年   4篇
  2014年   7篇
  2013年   7篇
  2012年   23篇
  2011年   21篇
  2010年   20篇
  2009年   17篇
  2008年   24篇
  2007年   28篇
  2006年   15篇
  2005年   17篇
  2004年   25篇
  2003年   18篇
  2002年   13篇
  2001年   9篇
  2000年   2篇
  1999年   2篇
  1998年   9篇
  1997年   3篇
  1996年   3篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1989年   1篇
  1988年   1篇
  1986年   1篇
  1985年   6篇
  1984年   4篇
  1982年   2篇
  1975年   4篇
  1971年   1篇
排序方式: 共有333条查询结果,搜索用时 0 毫秒
51.
In this paper, we consider the relationship between the congruence of cuspidal Hecke eigenforms with respect to Sp n (Z) and the special values of their standard zeta functions. In particular, we propose a conjecture concerning the congruence between Saito-Kurokawa lifts and non-Saito-Kurokawa lifts, and prove it under certain condition. Partially supported by Grant-in-Aid for Scientific Research C-17540003, JSPS.  相似文献   
52.
We consider a certain Dirichlet series of Rankin-Selberg type associated with two Siegel cusp forms of the same integral weight with respect to Spn(Z). In particular, we give an explicit formula for the Dirichlet series associated with the Ikeda lifting of cuspidal Hecke eigenforms with respect to SL2(Z). We also comment on a contribution to the Ikeda's conjecture on the period of the lifting.  相似文献   
53.
Several aspects of vortex motion are considered, with a special stress on the present status of idealization, such as point vortices or vortex filament. As an introduction, elements of vortices induced by the transient flow past an obstacle are considered and their role and development are stated.

Following this introduction, a general survey of the issues in this symposium is made sketchily. As an example, the motion of point vortices in the presence of an external flow or a boundary is discussed on the basis of the Hamiltonian formalism. The cases of linear flow and semicircular boundary are taken as examples of regular and chaotic motions. Secular behaviour of a pair of vortices in the flow is remarked.  相似文献   

54.
LaCuOSe is a wide band gap (~2.8 eV) semiconductor with unique optoelectronic properties, including room-temperature stable excitons, high hole mobility ~8 cm(2)/(Vs), and the capability of high-density hole doping (up to 1.7 × 10(21) cm(-3) using Mg). Moreover, its carrier transport and doping behaviors exhibit nonconventional results, e.g., the hole concentration increases with decreasing temperature and the high hole doping does not correlate with other properties such as optical absorption. Herein, secondary ion mass spectroscopy and photoemission spectroscopy reveal that aliovalent ion substitution of Mg at the La site is not the main source of hole doping and the Fermi level does not shift even in heavily doped LaCuOSe:Mg. As the hole concentration increases, the subgap optical absorption becomes more intense, but the increase in intensity does not correlate quantitatively. Transmission electron microscopy indicates that planar defects composed of Cu and Se deficiencies are easily created in LaCuOSe. These observations can be explained via the existence of a degenerate low-mobility layer and formation of complex Cu and Se vacancy defects with the assistance of generalized gradient approximation band calculations.  相似文献   
55.
We give an explicit formula for the twisted Koecher–Maaß series of the Duke–Imamoglu–Ikeda lift. As an application we prove a certain algebraicity result for the values of twisted Rankin–Selberg series at integers of half-integral weight modular forms, which was not treated by Shimura (J Math Soc Japan 33:649–672, 1981).  相似文献   
56.
A modified solvent microextraction with back extraction method (SME/BE) combined with high performance liquid chromatography and fluorescence detection (HPLC-FD) was developed for the determination of citalopram in human plasma. Extraction process was performed in a home-made total glass vial without using a teflon ring, usually employed in SME/BE. Citalopram was first extracted from 0.5 mL of plasma, modified with sodium hydroxide, into hexane. Back extraction step was then performed into 5.2 μL of 45 mM ammonium formate solution (pH 4) using a GC microsyringe. The extract was subsequently transferred into a liner-like vial and then injected into the HPLC system. An enrichment factor of 150 along with a good sample clean-up was obtained. The calibration curve showed linearity in the range of 1.0–130.0 ng mL−1 with regression coefficient corresponding to 0.992. This range covers therapeutic window and even lower amounts which is important in pharmacokinetic studies. Limits of detection and quantification, based on a signal to noise ratio (S/N) of 3 and 10, were 0.3 and 0.8 ng mL−1, respectively. The method was also applied for the determination of citalopram in plasma samples after oral administration of 40 mg single dose of citalopram.  相似文献   
57.
Unlike conventional electrospun polymer fibers deposited on a target electrode as a randomly oriented mesh, poly(p‐xylenetetrahydrothiophenium chloride) was electrospun into centimeters‐long yarns vertically on the surface of the electrode but parallel to the electric field. The diameter of the yarn was strongly affected by the concentration, spinning rate, and viscosity of the polymer solution, but less dependent on the applied voltage. The subsequent carbonization of thus‐electrospun yarns at 600–1000 °C resulted in uniaxially aligned carbon nanofibers with average diameters of 127–184 nm. On the basis of Raman spectra, the graphitic crystallite size and the molar fraction of graphite were estimated to be 1.2–1.4 and 0.21–0.24 nm, respectively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 305–310, 2008  相似文献   
58.
The reaction of helical quinone with alcohols in the presence of Brønsted acid such as para-toluenesulfonic acid (pTSA) or HCl proceeded smoothly to produce the corresponding alkoxy substituted oxa[9]helicenes in good yields.  相似文献   
59.
We have studied the algorithm for the automatic chromatic dispersion compensation using bit error rate (BER) and Q-factor optimization for realization of dynamically reconfigurable all-optical network. We have made sure good performance using the compensation system by laboratory experiments.  相似文献   
60.
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