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   82篇
  免费   18篇
  国内免费   16篇
化学   44篇
力学   15篇
综合类   2篇
数学   8篇
物理学   47篇
  2023年   2篇
  2022年   4篇
  2021年   5篇
  2020年   5篇
  2019年   8篇
  2018年   6篇
  2017年   1篇
  2016年   7篇
  2015年   6篇
  2014年   4篇
  2013年   5篇
  2012年   8篇
  2011年   6篇
  2010年   1篇
  2009年   3篇
  2008年   1篇
  2006年   4篇
  2005年   1篇
  2004年   2篇
  2003年   5篇
  2002年   1篇
  1998年   6篇
  1997年   7篇
  1996年   7篇
  1995年   3篇
  1994年   2篇
  1993年   2篇
  1992年   2篇
  1991年   1篇
  1983年   1篇
排序方式: 共有116条查询结果,搜索用时 78 毫秒
1.
30年前,甚至十几年前物理系还是一个众生向往的殿堂,那些决心献身科学并且品学兼优的佼佼者进入到这个领域,从而受到同龄人的尊敬和羡慕.一代优秀的物理学工作者就是在这个环境中成长起来,成为今天物理科研与教学领域的中坚力量.然而随着时代的发展,社会的需求,职业市场的选择以及人们价值观的改变,部分优秀的中学毕业生选择了更现实的领域,如经济、计算机等,他们毕业后可以较轻松地获得工作条件优越,报酬丰厚的职业.因而大量的人才从物理学,特别是纯物理学领域中流失了.这些年再加上出国留学热,甚至在高中毕业就已走上出国之路,对我们人才培养的冲击之大是难以估计的.物理学在许多学生及家长眼中已沦为第二等的学科,或是不得已的选择.  相似文献   
2.
钟纪泉  张学谦 《中国物理 C》1996,20(12):1087-1090
壳模型计算表明,1/2+[411]出现于157Tm核的基态可能是由非轴对称形变造成的.但是新近从157Yb衰变纲图给出的157Tm低激发谱中,指认了一个建立在1/2+[411]带头上的基态转动带,并认为该带的性质是轴对称的,提取了该带的惯性参数与脱耦合参数.通过对奇ATm核1/2+[411]转动带的系统分析,强调了在157Tm核中非轴对称γ自由度效应的重要性.  相似文献   
3.
Manganese‐ and cerium oxide‐modified titania catalysts were prepared by the deposition precipitation for the removal of elemental mercury (Hg0) from simulated yellow phosphorus off‐gas at low temperature. In addition, these catalysts were characterized by X‐ray diffraction, Brunauer–Emmett–Teller measurements, X‐ray photoelectron spectroscopy and field‐emission scanning electron microscope to determine the surface morphology of the obtained compounds and explore their formation mechanism. The results revealed that a Mn–Ce loading and reaction temperature of 10% and 150 °C, respectively, as well as a Mn/Ce molar ratio of 2:1, led to an optimal efficiency for the oxidation of elemental mercury. Furthermore, the effects of flue gas components were investigated. The presence of O2 clearly promoted the oxidation of Hg0. A CO atmosphere did not affect the Hg0 oxidation, when compared with N2, whereas the presence of H2S and water vapor inhibited the oxidation process. Furthermore, the X‐ray photoelectron spectroscopy spectra of Hg 4f revealed that the elemental mercury adsorbed by the catalyst is present as HgO. Finally, the Hg0 catalytic oxidation mechanism was discussed on the basis of the experimental results and characterization analysis.  相似文献   
4.
在热乙醇中合成了2-乙酰基噻吩缩异烟酰肼及其与Cd(II)、Cu(II)和Zn(II)形成的三种配合物;利用元素分析、摩尔电导测定,以及红外光谱、紫外光谱和热分析确定了合成产物的组成和结构,并测定了配合物的组成及发光性质.结果表明,酰肼的配位方式的不同导致配合物呈现不同的发光性质.  相似文献   
5.
Clifford algebraic geometry corresponds to Minkowski space. Using the discrete structure of Minkowski space, we can abstract a class n-dimensional hyperbolic Hilbert phase space. To discussing the causality of physical event in Minkowski space, we can obtain the geometrical interpretation of uncertainty relation.  相似文献   
6.
吕景文  李学谦 《光学学报》1994,14(12):285-1287
研制出了掺铈、钐的滤紫外和红外光的硼硅酸盐荧光玻璃,测试了该玻璃的吸收光谱和荧光谱,并用其做了固体激光器工作物质的紫外和红外滤光套,能使激光效率提高25%-505,从而促进固体激光器的微型化和实用化。  相似文献   
7.
A series of adsorbents were studied for removal efficiency of carbon disulfide (CS2) under micro-oxygen conditions. It was found that activated carbon modified by Cu and cobalt sulfonated phthalocyanine (CoSPc) denoted as ACCu–CoSPc showed significantly enhanced adsorption ability. Reaction temperature was found to be a key factor for adsorption, and 20 °C seems to be optimal for CS2 removal. Samples were analyzed by N2-BET, XRD, XPS, SEM–EDS and CO2-TPD. The characterization results demonstrated that large quantities of SO4 2? anions were formed and adsorbed in the reaction process. SO2, CS2 and COS were detected in the effluent gas generated from the temperature programmed desorption of ACCu–CoSPc–CS2. Therefore, it can be concluded that ACCu–CoSPc most likely acted as a catalyst in the adsorption/oxidation process on the surface of the impregnated sample. The generated sulfide and sulfur oxide can cover the active sites of adsorbents, resulting in pronounced reduction of adsorbent activity. Finally, the exhausted ACCu–CoSPc can be regenerated by thermal desorption.  相似文献   
8.
In this work, a new monoclonal antibody specific for glycyrrhizic acid was prepared and characterized. A hybridoma secreting an anti‐glycyrrhizic acid monoclonal antibody was produced by fusing splenocytes from a mouse immunized against a glycyrrhizic acid–bovine serum albumin conjugate with the hypoxanthine–aminopterin–thymidine‐sensitive mouse myeloma cell line (Sp2/0‐Ag14). Subsequently, an indirect, competitive enzyme‐linked immunosorbent assay for glycyrrhizic acid was developed using the monoclonal antibody. In this assay, we detected an effective measuring range of 78.12–2500 ng/mL. Both intra‐assay and inter‐assay repeatability and precision were achieved, with relative standard deviations lower than 10%. In addition, glycyrrhizic acid levels in both formulated Chinese medicines and biological samples were determined with high sensitivity and efficiency. We then successfully developed a reliable immunoaffinity chromatography to separate glycyrrhizic acid completely from its parent medicine. These methods will contribute to further research investigations to better understand the interactions of glycyrrhizic acid with other drugs in the complex system of traditional Chinese medicine.  相似文献   
9.
本文用序列二次规划方法(SQP)结合Wolfe-Powell不精确线性搜索准则求解非线性规划问题.Wolfe-Powell准则是一种能够使目标函数获得充分下降而运行时间较省的确定步长方法.不精确线性搜索滤子方法比较其它结合精确线性搜索和信赖域方法求解问题的滤子方法更灵活更易实现.如果目标函数的预测下降量为负,我们的工作将主要利用可行恢复项改善可行性.一般条件下,本文提出的算法较易实现,且具有全局收敛性.数值试验显示了算法的有效性.  相似文献   
10.
新重丰中子同位素239Pa   总被引:1,自引:0,他引:1  
用50MeV/u 18O离子同天然铀靶反应产生了新重丰中子同位素239Pa.用放射化学法从反应产物中分离Pa活性,通过观测239Pa及子体239U衰变所得到的结果显示:首次合成和鉴别了新重丰中子核素239Pa,并测定出239Pa的半衰期为106±30min.  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