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   162篇
  免费   17篇
  国内免费   14篇
化学   73篇
力学   40篇
数学   50篇
物理学   30篇
  2023年   4篇
  2022年   10篇
  2021年   11篇
  2020年   13篇
  2019年   13篇
  2018年   12篇
  2017年   7篇
  2016年   6篇
  2015年   8篇
  2014年   8篇
  2013年   8篇
  2012年   9篇
  2011年   12篇
  2010年   11篇
  2009年   6篇
  2008年   8篇
  2007年   8篇
  2006年   10篇
  2005年   2篇
  2004年   5篇
  2003年   1篇
  2002年   3篇
  2001年   1篇
  2000年   2篇
  1999年   2篇
  1998年   2篇
  1997年   3篇
  1996年   1篇
  1995年   1篇
  1994年   2篇
  1993年   2篇
  1992年   2篇
排序方式: 共有193条查询结果,搜索用时 0 毫秒
81.
Chemodynamic therapy kills cancer cells with reactive oxygen species generated by endogenous triggers in the tumor microenvironment. Although chemodynamic therapy is blossoming in recent years, their therapy process still faces a series of hampers. The unknown catalytic activity of chemodynamic therapy reagents may lead to unpredictable therapy effects, so it is necessary to reveal the therapeutic mechanism of chemodynamic therapy and develop self-monitoring probes. In this mini-review, we summarize and illustrate the most recent progress of chemodynamic therapy, focusing on the applications of magnetic imaging and optical imaging probe for monitoring cancer chemodynamic therapy. Furthermore, we also discuss the potential challenges and the further directions of this field.  相似文献   
82.
A molecularly thin layer of 2‐aminobenzenethiol (2‐ABT) was adsorbed onto nanoporous p‐type silicon (b‐Si) photocathodes decorated with Ag nanoparticles (Ag NPs). The addition of 2‐ABT alters the balance of the CO2 reduction and hydrogen evolution reactions, resulting in more selective and efficient reduction of CO2 to CO. The 2‐ABT adsorbate layer was characterized by Fourier transform infrared (FTIR) spectroscopy and modeled by density functional theory calculations. Ex situ X‐ray photoelectron spectroscopy (XPS) of the 2‐ABT modified electrodes suggests that surface Ag atoms are in the +1 oxidation state and coordinated to 2‐ABT via Ag?S bonds. Under visible light illumination, the onset potential for CO2 reduction was ?50 mV vs. RHE, an anodic shift of about 150 mV relative to a sample without 2‐ABT. The adsorption of 2‐ABT lowers the overpotentials for both CO2 reduction and hydrogen evolution. A comparison of electrodes functionalized with different aromatic thiols and amines suggests that the primary role of the thiol group in 2‐ABT is to anchor the NH2 group near the Ag surface, where it serves to bind CO2 and also to assist in proton transfer.  相似文献   
83.
84.
Chen  Qi  Wu  Di  Zhang  Zhifei 《中国科学 数学(英文版)》2023,66(4):679-722
Science China Mathematics - In this paper, we study the stability of shear flows of Prandtl type as $$left({Uleft({y/sqrt nu} right),0} right)$$ for the steady Navier-Stokes equations under a...  相似文献   
85.
Luo W  Chen Z  Zhu L  Chen F  Wang L  Tang H 《Analytica chimica acta》2007,588(1):117-122
A sensitive method for carbon tetrachloride (CCl4) determination has been developed with the aid of ultrasonic oxidation decolorization of methyl orange (MO). It is found that the ultrasonic oxidation decolorization rate of MO can be significantly promoted by adding a little amount of CCl4. The increased ultrasonic decolorization rate of MO is strongly dependent on the concentration of CCl4 added, and a linear correlation is observed between the amount of CCl4 and the decolorization rate of MO in the ultrasonic oxidation process. Thus, the CCl4 determination is transformed to a simple and direct determination of the decoloration extent of MO solution at a given concentration. As an indirect spectrophotometric determination of CCl4, the new method is sensitive and easy of operation with a maximum wavelength of 508 nm, molar absorptivity of 3.83 × 104 L mol−1 cm−1, and a Sandell sensitivity of 7.96 × 10−3 μg cm−2. Under optimized conditions, Beer's law is obeyed in the range of 0.4-20 mg L−1 of CCl4 (DL = 0.19 mg L−1, r = 0.9996). The concentrations of CCl4 in several practical samples have been determined satisfactorily by using this method.  相似文献   
86.
本文介绍了空气动力学中几个基本概念与定律的起源。其中,升力与阻力分别是空气对物体作用力的两个方向上的分量,它们均是由空气与物体的相对运动而产生的,并与该运动速度的平方成正比。库塔儒可夫斯基升力环量定理给出了翼型升力与翼型绕流之间的关系,开启了20世纪早期各国对翼型性能的研究。同时,鉴于理想流体圆柱绕流无阻力的理论结果与实验观察存在的矛盾开始激发人们对黏性流体运动的研究兴趣,并由此诞生了纳维斯托克斯方程组。而后普朗特提出边界层概念,巧妙解决了局部流动与整体流动的关系问题。针对大展弦比直机翼,普朗特又提出了基于升力线假设的升力线模型,并根据翼型气动数据得到三维机翼的气动性能。  相似文献   
87.
88.
饱和多孔介质耦合系统的变分原理   总被引:2,自引:0,他引:2  
本文采用变积方法,建立了等温准静态下饱和多孔介质的六类变量的广义变分原理.在此基础上,通过引入约束条件得到各级变分原理,其中包括五类变量,四类变量,三类变量和二类变量的变分原理.除得到文献中已有的变分原理外,本文给出了许多新的变分原理,为建立饱和多孔介质的有限元模型提供了基础.  相似文献   
89.
Based on the weak form quadrature element method, a perturbation approach is developed. Waves propagating in periodic beams on a nonlinear elastic foundation are studied by using the new proposed method. The feasibility and accuracy of the proposed method are verified by comparing the present results with those available in literatures in linear cases. Detailed modal analysis of the linear cases is conducted in order to obtain the dispersion relations of the nonlinear cases. The theoretical results show that the dispersion relations of the nonlinear cases are amplitude dependent. Furthermore, the effects of geometric parameters and degree of nonlinearity on the amplitude‐dependent dispersion relations are discussed in detail. This work provides a new method for analyzing the dispersion relations of nonlinear periodic structures and gives some useful guidelines for designing periodic beams or pipelines with nonlinear structure–foundation interaction. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
90.
In two space dimension, we prove the global existence of smooth solutions to a coupled microscopic-macroscopic co-rotational FENE dumbbell model which arises from the kinetic theory of diluted solutions of polymeric liquids with noninteracting polymer chains.  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