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   68篇
  免费   9篇
  国内免费   8篇
化学   62篇
晶体学   1篇
力学   10篇
数学   3篇
物理学   9篇
  2023年   2篇
  2022年   3篇
  2021年   6篇
  2020年   8篇
  2019年   1篇
  2018年   5篇
  2017年   4篇
  2016年   4篇
  2015年   4篇
  2014年   3篇
  2012年   8篇
  2011年   4篇
  2010年   2篇
  2008年   3篇
  2007年   3篇
  2006年   2篇
  2005年   2篇
  2004年   3篇
  2003年   2篇
  2002年   3篇
  2000年   1篇
  1999年   6篇
  1998年   2篇
  1993年   1篇
  1992年   2篇
  1990年   1篇
排序方式: 共有85条查询结果,搜索用时 31 毫秒
1.
2.
3.
An immersed smoothed point interpolation method using 3‐node triangular background cells is proposed to solve 2D fluid‐structure interaction problems for solids with large deformation/displacement placed in incompressible viscous fluid. In the framework of immersed‐type method, the governing equations can be decomposed into 3 parts on the basis of the fictitious fluid assumption. The incompressible Navier‐Stokes equations are solved using the semi‐implicit characteristic‐based split scheme, and solids are simulated using the newly developed edge‐based smoothed point interpolation method. The fictitious fluid domain can be used to calculate the coupling force. The numerical results show that immersed smoothed point interpolation method can avoid remeshing for moving solid based on immersed operation and simulate the contact phenomenon without an additional treatment between the solid and the fluid boundary. The influence from information transfer between solid domain and fluid domain on fluid‐structure interaction problems has been investigated. The numerical results show that the proposed interpolation schemes will generally improve the accuracy for simulating both fluid flows and solid structures.  相似文献   
4.
贾志谦 《大学化学》2007,22(5):33-35
介绍超滤回收溶液中聚乙二醇的实验。采用Dragendorff试剂方法测定聚乙二醇浓度和截留率,研究操作条件对渗透速率的影响,探讨膜污染机理以及清洗方法,并根据实验中发现的问题,改进了Dragendorff测定方法。  相似文献   
5.
We describe the first example of Rh-catalyzed intermolecular C-alkylation of cyclic 1,2-diketones using simple terminal olefins as alkylating agents. Aminopyridine is employed as a recyclable directing group. First, it reacts with ketones to give enamines and delivers Rh to activate the vinyl C-H bonds in the same pot; second, it can be cleaved off and recovered via hydrolysis. A broad range of olefins can be utilized as substrates, including aliphatic, aromatic olefins and vinyl esters. The efficiency of this method is also demonstrated in the synthesis of a natural flavoring compound, 3-ethyl-5-methyl-1,2-cyclopentadione (one-pot 53% yield vs a previous four-step route 16% yield from the same starting material). This work is expected to serve as a seminal study toward catalytic ketone α-alkylation with unactivated olefins.  相似文献   
6.
The morphological evolution on the size and shape of Ge island on the Si(100) surface by depositing and subsequent annealing processes is studied in situ by using scanning tunneling microscopy at ultrahigh vacuum environment. A slower growth rate is maintained when the islands grow to larger sizes beyond the wetting layers. While at room temperature, the epitaxial strain is relieved by the formation of three‐dimensional islands (so‐called ‘hut’ clusters). When the sample is annealed at 200 °C, the strain is relieved by forming pits, having the circular cone shape but with their apex pointing down, with Ge clusters formed at the rim of pits. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
7.
The rational design of high‐performance fluorescent materials for cancer targeting in vivo is still challenging. A unique molecular design strategy is presented that involves tailoring aggregation‐induced emission (AIE)‐active organic molecules to realize preferable far‐red and NIR fluorescence, well‐controlled morphology (from rod‐like to spherical), and also tumor‐targeted bioimaging. The shape‐tailored organic quinoline–malononitrile (QM) nanoprobes are biocompatible and highly desirable for cell‐tracking applications. Impressively, the spherical shape of QM‐5 nanoaggregates exhibits excellent tumor‐targeted bioimaging performance after intravenously injection into mice, but not the rod‐like aggregates of QM‐2.  相似文献   
8.
时滞对结构振动半主动控制效果的影响   总被引:5,自引:0,他引:5  
应用磁流变阻尼器对结构振动进行控制,采用最优控制原理设计了控制器,给出在地震激励下结构半主动控制的仿真计算。研究了时滞对结构振动半主动控制效果的影响。数值结果表明:本文设计的半主动控制策略可有效地减小结构的振动响应,时滞对磁流变半主动控制效果随着时滞的增大而变差,但时滞不会导致该反馈控制系统的失稳。  相似文献   
9.
Trans-Resveratrol (RV) is a natural polyphenol characterized by interesting pleiotropic potentials and health benefits, but its administration is hampered by a unsatisfactory pharmacokinetics. Various approaches have been identified to circumvent it: among them, 2-hydroxypropyl-β-cyclodextrins (HPβCD) are valuable strategy. Here, we compare the employment of HPβCD based formulation with a resveratrol nanosupension (obtained by diluting a RV ethanol solution with PBS, added of 0.05 % hydroxyethylcellulose) to improve RV bioavailability after oral administration to mice. The inclusion of RV in HPβCD was confirmed by differential scanning calorimetry, Fourier transformed infrared spectroscopy, and phase solubility study. The two formulations were orally administered to BALB-c mice. RV concentrations in plasma and tissues were detected at different time (0–120 min) by HPLC method. HPβCD complexation mediate a approximately fourfold increment in plasma RV Cmax and  approximately twofold augment of RV AUC0-120 in comparison with RV nanosuspension. Similar increased concentrations were observed in heart, liver, kidney and gut. In particular, HPβCD mediated a 5.5-folds increase of resveratrol concentration in the intestine, in comparison to the nanosuspension. In conclusion, based on our results, HPβCD complexation is a promising approach to increase the oral bioavailability of RV. Moreover, the achievement of high concentrations in gut suggested a potential employment of oral RV-HPβCD as anti-inflammatory/chemopreventive agent in this tissue.  相似文献   
10.
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