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   129篇
  免费   6篇
  国内免费   2篇
化学   76篇
力学   1篇
数学   9篇
物理学   51篇
  2022年   3篇
  2021年   7篇
  2020年   3篇
  2019年   9篇
  2018年   14篇
  2017年   4篇
  2016年   11篇
  2015年   9篇
  2014年   10篇
  2013年   9篇
  2012年   6篇
  2011年   7篇
  2010年   6篇
  2009年   12篇
  2008年   7篇
  2007年   6篇
  2006年   3篇
  2005年   5篇
  2004年   5篇
  2001年   1篇
排序方式: 共有137条查询结果,搜索用时 15 毫秒
131.
We define generalized cat states as linear superpositions of the semi-coherent states. They can be considered as superpositions of two distinguishable components of the Schrödinger cat states. We study the statistical properties of the introduced states in detail. The physical properties of these states, like the sub-Poissonian statistics and normal-order as well as amplitude-squared squeezing effect, are discussed analytically. Moreover, we find some interesting properties of their optical tomogram derived in terms of the exponential function. Finally, we suggest a new theoretical framework for preparing generalized cat states.  相似文献   
132.
A novel parallel source implementation approach to near-infrared tomography is demonstrated through spectral encoding of the light delivery. This new technique allows many sources to be input into the tissue at the same time, and a high-resolution spectrometer is used to spatially spread out the signals from each spectrally encoded source. The parallel sampling of all sources at all detection locations renders rapid imaging. Acquisition of complete tomographic data sets at a video rate of 35 frames/s is achieved for imaging of a 6.35 mm diameter inclusion with an absorption coefficient of 0.01 mm(-1) and a reduced scattering coefficient of 1.5 mm(-1) that is moving along a circular path inside a 1% Intralipid solution.  相似文献   
133.
Spectra of the nitrous oxide dimer (N2O)2 are studied in the region of the N2O nu1 fundamental band around 2230 cm-1 using a rapid-scan tunable diode laser spectrometer to probe a pulsed supersonic jet expansion. The previously known band of the centrosymmetric nonpolar dimer is analyzed in improved detail, and a new band is observed and assigned to a polar isomer of (N2O)2. This polar form of the dimer has a slipped parallel structure, rather similar to the slipped antiparallel structure of the nonpolar form but with a slightly larger intermolecular distance. The accurate rotational parameters determined here should enable a microwave observation of the polar N2O dimer. The need for a modern ab initio investigation of the N2O-N2O intermolecular potential energy surface is emphasized.  相似文献   
134.
An electrochemical sensor for simultaneous quantification of Levodopa (L‐dopa) and Carbidopa (C‐dopa) using a β‐cyclodextrin/poly(N‐acetylaniline) (β‐CD/PNAANI) modified carbon paste electrode has been developed. Preconcentrating effect of β‐CD as well as its different inclusion complex stability with L‐dopa and C‐dopa was used to construct an electrochemical sensor for quantification of these important analytes. The overlapping anodic peaks of L‐dopa and C‐dopa at 810 mV on bare carbon paste electrode resolved in two well‐defined voltammetric peaks at 450 and 880 mV vs. Ag/AgCl, respectively, with a drastic enhancement of the anodic peak currents. Under optimized conditions, linear calibration curves were obtained in the ranges of 0.5–117 µM and 1.6–210 µM with detection limits down to 0.2 and 0.8 µM for L‐dopa and C‐dopa, respectively. The proposed electrode was successfully applied for the determination of L‐dopa /C‐dopa in pharmaceutical formulations and the results were in close agreement with the labeled values.  相似文献   
135.
In this paper, we consider a Sturm–Liouville operator with eigenparameter-dependent boundary conditions and transmission conditions at a finite number of interior points. We introduce a Hilbert space formulation such that the problem under consideration can be interpreted as an eigenvalue problem for a suitable self-adjoint linear operator. We construct Green function of the problem and resolvent operator. We establish the self-adjointness of the discontinuous Sturm–Liouville operator.  相似文献   
136.
Aluminum chloride (AlCl3) efficiently catalyzes one‐pot multicomponent condensation of enolizable ketones or alkyl acetoacetates with aldehydes, acetonitrile and acetyl chloride to afford β‐acetamido ketone or ester derivatives in high to excellent yields and in relatively short reaction times. Moreover, by this synthetic method, some novel β‐acetamido ketones and esters (i.e. one complex structure) are prepared.  相似文献   
137.
Spectrally resolved bioluminescence optical tomography is an approach to recover images of luciferase activity within a volume using multiwavelength emission data from internal bioluminescence sources. The underlying problem of uniqueness associated with nonspectrally resolved intensity-based bioluminescence tomography is highlighted. Reconstructed images of bioluminescence are presented by using as input both simulated and real multiwavelength data from a tissue-simulating phantom. The location of the internal bioluminescence is obtained with 1 mm accuracy. Further, the amplitude of the reconstructed source is proportional to the actual bioluminescence intensity.  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