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   135篇
  免费   14篇
  国内免费   29篇
化学   84篇
力学   7篇
数学   54篇
物理学   33篇
  2023年   8篇
  2022年   5篇
  2021年   6篇
  2020年   12篇
  2019年   7篇
  2018年   9篇
  2017年   4篇
  2016年   11篇
  2015年   7篇
  2014年   10篇
  2013年   12篇
  2012年   10篇
  2011年   20篇
  2010年   13篇
  2009年   11篇
  2008年   5篇
  2007年   5篇
  2006年   4篇
  2005年   3篇
  2003年   3篇
  2002年   1篇
  2001年   3篇
  2000年   3篇
  1999年   3篇
  1998年   1篇
  1997年   1篇
  1994年   1篇
排序方式: 共有178条查询结果,搜索用时 15 毫秒
1.
Near-infrared (NIR) light-driven photoelectrochemical (PEC) sensing is a highly promising analytical technique, especially for in situ bioanalysis, due to the deep penetration capability and minimal invasiveness of NIR light. In this mini review, we provide a brief overview of recently developed NIR PEC sensors, focusing on NIR light-responsive materials and the representative applications of this type of PEC sensor. Future perspectives for NIR PEC sensors are also described.  相似文献   
2.
《中国化学快报》2020,31(7):1855-1858
By virtue of electrochemistry, a series of α,α-dihaloacetophenones were easily obtained with good to excellent yields. This electrochemical procedure was taken in a divided cell with constant current in aqueous media. The reaction can be carried out smoothly at room temperature under metal and oxidant free condition, which provides an eco-friendly synthesis for the α,α-dihaloacetophenone derivatives.  相似文献   
3.
《中国化学快报》2020,31(12):2989-2990
The recent molecular iodine catalyzed [1,2]-rearrangement of aryl amines and 3-amino-1H-indazolesfor the synthesis of 1,2,3-benzotriazines is highlighted.  相似文献   
4.
In this article, we shall give a brief review on the fully discrete mixed finite element method for general optimal control problems governed by parabolic equations. The state and the co-state are approximated by the lowest order Raviart–Thomas mixed finite element spaces and the control is approximated by piecewise constant elements. Furthermore, we derive a posteriori error estimates for the finite element approximation solutions of optimal control problems. Some numerical examples are given to demonstrate our theoretical results.  相似文献   
5.
An efficient time‐stepping procedure is investigated for a two‐dimensional compressible miscible displacement problem in porous media in which the mixed finite element method with Raviart‐Thomas space is applied to the flow equation, and the transport one is solved by the symmetric interior penalty discontinuous Galerkin approximation on Cartesian meshes. Based on the projection interpolations and the induction hypotheses, a superconvergence error estimate is obtained. During the analysis, an extension of the Darcy velocity along the Gauss line is also used in the evaluation of the coefficients in the Galerkin procedure for the concentration. © 2013 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2013  相似文献   
6.
In this paper, we discuss nonlocal Cauchy problems for fractional order nonlinear differential systems. Firstly, an important matrix associated with fractional order and two functionals are constructed. Further, some sufficient conditions which guarantee such matrix convergent to zero matrix are presented. Secondly, by using three fixed point theorems via the techniques that use convergent to zero matrix and vector norm, some existence results for the solutions of such fractional order nonlinear differential systems are given under different conditions. Finally, some examples are given to illustrate the results.  相似文献   
7.
Albeit its chemical inertness, rare gas doping can substantially enhance the quantum size effect of nanocrystals, yet little attention has been paid on this fascination and the mechanism behind remains unclear. Here, we show that the rare gas dopant breaks bonds of its neighboring atoms, which effects the same to atomic under‐coordination on the bond strain, energy quantum entrapment, and valence electron polarization of Li and Na clusters. Consistency between density functional theory calculation and the bond‐order‐length‐strength correlation prediction revealed that the bond strain by 16.86% and 21.12% before and after He doping for Na30 clusters. Observations suggest an effective yet simple means to modulate the physical properties by doping the inert gases.  相似文献   
8.
In this paper, gas-assisted magnetic separation (GAMS), a technique that combines magnetic separation with flotation, was investigated for the potential large-scale separation of proteins. The GAMS process includes adsorption of target proteins and magnetic separation to recover protein-loaded magnetic particles from the dilute biosuspension with the assistance of bubbles. Microsized ethylenediamine-functionalized poly(glycidyl methacrylate) superparamagnetic microspheres (MPMs) and bovine serum albumin (BSA) were used as a model system. The feasibility of GAMS for capturing BSA-loaded MPMs from an appropriate medium was shown. High recovery of BSA-loaded MPMs was obtained by simple adjustment of the initial solution pH without extra detergents and antifoaming agents. The GAMS conditions were consistent with the adsorption conditions, and no proteins were desorbed from the MPMs during this process. Under the optimal conditions, the separation rate and recovery percentage reached 410 mL/min and 98% in 0.61 min, respectively. Conformational changes of BSA during the GAMS process were investigated by fluorescence spectroscopy and circular dichroism spectrometry.  相似文献   
9.
Embedding endohdedral metallofullerenes (EMFs) into electron donor–acceptor systems is still a challenging task owing to their limited quantities and their still largely unexplored chemical properties. In this study, we have performed a 1,3‐dipolar cycloaddition reaction of a corrole‐based precursor with Sc3N@C80 to regioselectively form a [5,6]‐adduct ( 1 ). The successful attachment of the corrole moiety was confirmed by mass spectrometry. In the electronic ground state, absorption spectra suggest sizeable electronic communications between the electron acceptor and the electron donor. Moreover, the addition pattern occurring at a [5,6]‐bond junction is firmly proven by NMR spectroscopy and electrochemical investigations performed with 1 . In the electronically excited state, which is probed in photophysical assays with 1 , a fast electron‐transfer yields the radical ion pair state consisting of the one‐electron‐reduced Sc3N@C80 and of the one‐electron‐oxidized corrole upon its exclusive photoexcitation. As such, our results shed new light on the practical work utilizing EMFs as building blocks in photovoltaics.  相似文献   
10.
A bidentate ligand, 1‐{4‐[4‐(1H‐1,2,4‐triazol‐1‐yl)phenoxy]phenyl}‐1H‐1,2,4‐triazole (TPPT), has been designed and synthesized. By using TPPT as a building block for self‐assembly with Cd(NO3)2 ? 4 H2O and CdCl2 ? 10.5 H2O, novel 1D double‐chain {[Cd(TPPT)(NO3)2] ? 3 H2O}n ( 1 ) and 2D (4,4) layer [Cd(TPPT)Cl2(H2O)]n ( 2 ) have been constructed. When 1 was employed as a precursor and exposed to DMF or N,N′‐dimethylacetamide (DMAC), the crystals of 1 dissolved and reassembled into two types of brown block‐shaped crystals of 1D double chains: {[Cd(TPPT)2(NO3)2] ? DMF}n ( 1 a ) and {[Cd(TPPT)2(NO3)2] ? DMAC}n ( 1 b ). The anion‐exchange reactions of complex 2 have also been investigated. After gently stirring crystals of 2 in CHCl3/C2H5OH/H2O containing NaBr, NaI ? 2 H2O, or NaOAc ? 3 H2O, the crystals retained their crystalline appearances. A remarkable single crystal to single crystal transformation was observed and 1D double chains of {[Cd(TPPT)Br2] ? C2H5OH}n ( 2 a ) and {[Cd(TPPT)2I2] ? CHCl3}n ( 2 b ), and 1D single chains of [Cd(TPPT)(H2O)2(CH3COO)2]n ( 2 c ), can be obtained. Luminescent properties indicate that 1 shows excellent selectivity for Ca2+ and cyano complexes. To the best of our knowledge, this is the first example of a luminescent probe for Ca2+ based on triazole derivatives.  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