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   37篇
  免费   18篇
  国内免费   8篇
化学   25篇
力学   1篇
数学   12篇
物理学   25篇
  2021年   3篇
  2020年   1篇
  2019年   1篇
  2016年   2篇
  2015年   5篇
  2013年   2篇
  2012年   4篇
  2011年   4篇
  2010年   6篇
  2009年   9篇
  2008年   3篇
  2007年   1篇
  2006年   2篇
  2005年   4篇
  2004年   1篇
  2002年   2篇
  2000年   5篇
  1999年   1篇
  1998年   2篇
  1994年   1篇
  1992年   2篇
  1990年   1篇
  1988年   1篇
排序方式: 共有63条查询结果,搜索用时 709 毫秒
41.
42.
Polymeric resins are practically important adsorbents in a wide variety of applications, but they generally suffer from low surface areas and limited functionalized adsorption sites owing to their closely compacted and tangled polymeric chains. A metal–organic framework (MOF)–polymer composite with enhanced adsorption capacity against the compacted polymeric resins was reported. The strategy to incorporate functionalized oligomer within the cavities of the MOF was demonstrated by the preparation of MIL‐101(Cr) incorporated with N‐methyl‐d ‐glucamine‐based organosiloxane polymer. The resulting MOF composite shows high efficiency for the removal of boric acid from water because of exceptionally high loading of functional groups responsible for the boron adsorption. This material offers promising perspectives for boron removal applications in seawater desalination.  相似文献   
43.
合肥光源升级改造任务已基本完成,注入器实现满能量注入。为适应新的注入器束流强度的测量需求,设计了新的注入器束流强度测量系统,该系统利用安装在真空腔上的3个快速束流变压器(FCT)和2个积分束流变压器(ICT),能够实现束流流强和电荷量的非拦截实时测量。为了准确获取束流参数,首先对束流变压器(CT)传输电缆进行了在线和离线标定;由于ICT输出信号信号幅度较小,噪声大,设计了低噪声前置放大器以改善信噪比;考虑低频谐波噪声和Kicker噪声的干扰,软件中通过适当的算法对噪声进行了处理;最后给出了部分在线实验结果。实验结果表明,束流传输效率约为27.4%,注入效率约为44.3%。  相似文献   
44.
We have succeeded in preparing magnetically anisotropic SmCo5 ribbons with high permanent performance by single-roller melt spinning at low wheel velocity. The anisotropy is associated with a crystallographic texture formed during melt-spinning process, with the c-axis parallel to the longitudinal direction of the ribbons. The formation of the crystallographic texture is attributed to a directional solidification process resulting from a thermal gradient. A remanence of 9.1 kG, remanence ratio of 0.9, intrinsic coercivity of 16.2 kOe and energy product of 18.2 MGOe at room temperature are obtained in the melt-spun and subsequently annealed SmCo5 ribbons prepared at 5 m/s.  相似文献   
45.
 本文在0~0.8 GPa的压力范围内对金属玻璃Cu100-xZrx(x=70,75)进行了室温下的电阻测量。利用实验得到的负的电阻-压力系数αp及推广的Ziman理论着重计算并讨论了压力下d波相移η2(EF)项对αp的贡献。  相似文献   
46.
Two classes of edge domination in graphs   总被引:2,自引:0,他引:2  
Let (, resp.) be the number of (local) signed edge domination of a graph G [B. Xu, On signed edge domination numbers of graphs, Discrete Math. 239 (2001) 179-189]. In this paper, we prove mainly that and hold for any graph G of order n(n?4), and pose several open problems and conjectures.  相似文献   
47.
The solubilities of cholesterol and desmosterol in binary solvent mixtures of n-hexane + ethanol at temperatures of 293.2–323.2 K were determined by a static equilibrium method. The solubilities increase with temperature and go through a maximum at a specific solvent composition. The fusion enthalpy ΔfusH and the melting point Tm, determined by differential scanning calorimeter (DSC), are 28.5 kJ/mol, 421.7 K for cholesterol and 15.9 kJ/mol, 388.2 K for desmosterol, respectively. The solubilities of cholesterol and desmosterol in pure n-hexane or ethanol follow a linear Van’t Hoff relation with temperature. Activity models, such as Wilson, NRTL and UNIQUAC models were used to correlate and predict the solubilities of cholesterol and desmosterol in n-hexane + ethanol mixed solvents. The interaction parameters were expressed as a function of temperature.  相似文献   
48.
On signed cycle domination in graphs   总被引:2,自引:0,他引:2  
Baogen Xu 《Discrete Mathematics》2009,309(4):1007-1387
Let G=(V,E) be a graph, a function f:E→{−1,1} is said to be an signed cycle dominating function (SCDF) of G if ∑eE(C)f(e)≥1 holds for any induced cycle C of G. The signed cycle domination number of G is defined as is an SCDF of G}. In this paper, we obtain bounds on , characterize all connected graphs G with , and determine the exact value of for some special classes of graphs G. In addition, we pose some open problems and conjectures.  相似文献   
49.
新型跑道腔式束流位置监测器   总被引:2,自引:2,他引:0       下载免费PDF全文
系统提出了一种新的腔式束流位置监测器(BPM),即跑道型腔式BPM,并使用微波工作室软件进行了理论研究和模拟计算,提出了通用设计方法。跑道型腔式BPM的金属腔部分具有跑道形横截面,引出束流位置偏移激励起的一对偶极模式作为束流位置信号。该方案的偶极模式极化方向固定,频率分离,可以解决随机误差产生的横向串扰问题,其理论位置分辨力可以达到15 nm。  相似文献   
50.
On edge domination numbers of graphs   总被引:1,自引:0,他引:1  
Let and be the signed edge domination number and signed star domination number of G, respectively. We prove that holds for all graphs G without isolated vertices, where n=|V(G)|?4 and m=|E(G)|, and pose some problems and conjectures.  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