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   261篇
  免费   20篇
  国内免费   46篇
化学   174篇
晶体学   2篇
力学   19篇
综合类   1篇
数学   54篇
物理学   77篇
  2023年   8篇
  2022年   12篇
  2021年   16篇
  2020年   13篇
  2019年   13篇
  2018年   10篇
  2017年   10篇
  2016年   12篇
  2015年   8篇
  2014年   21篇
  2013年   19篇
  2012年   19篇
  2011年   15篇
  2010年   15篇
  2009年   19篇
  2008年   20篇
  2007年   19篇
  2006年   8篇
  2005年   6篇
  2004年   5篇
  2003年   4篇
  2002年   6篇
  2001年   5篇
  2000年   1篇
  1999年   13篇
  1998年   6篇
  1997年   1篇
  1996年   5篇
  1995年   4篇
  1994年   1篇
  1993年   3篇
  1992年   3篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
  1987年   2篇
  1984年   1篇
  1983年   1篇
排序方式: 共有327条查询结果,搜索用时 765 毫秒
91.
殷志祥  张世昆 《实验力学》1995,10(3):252-256
本文根据晶体光塑性材料氯化银光力学性能的研究,提出了对于具有拉伸、压缩屈服特性不同的光弹塑性材料所应满足的应力、应变相似转换关系。  相似文献   
92.
本文对晶体光塑性材料氯化银在单轴和双轴应力状态下的屈服轨迹进行了测试,给出了在σ_1σ_2平面上的屈服轨迹,为深入了解该材料屈服特性和用该材料模拟研究实际问题提供了实验根据。  相似文献   
93.
姚志祥  罗国煜 《力学学报》2003,11(4):360-366
随着城市化进程加快,济南市在城市建设中面临日益严重的环境工程地质问题。为了更好地服务于城市建设,做好岩土地基的工程地质环境质量评价与分区有重要实际意义。本文分析了济南市区的工程地质环境条件,研究了济南市区岩土地基工程地质环境质量评价模型与优势指标,并采用BP神经网络模型对济南市区的岩土地基工程地质环境质量进行评价与分级。  相似文献   
94.
An organic-inorganic hybrid functionalized material was successfully synthesized by a surface molecular imprinting technique combined with a nonhydrolytic sol-gel (NHSG) process using acrylamide (AA) as the template, methacrylic acid as the functional monomer, methacryloxypropyltrimethoxysilane as the cross-linker and magnetic chitosan (CTS) microspheres as the support material. The adsorption ability and selectivity of this material toward AA was characterized. Experimental results showed that the imprinted polymer exhibited better recognition and selective performance toward AA than the nonimprinted polymer (NIP). The saturated binding capacity (Q max) was 104.68 mg/g, and the equilibrium dissociation constant was 263.16 mg/mL. This prepared material also offered fast kinetics for the adsorption and desorption of AA. After shaking for 5 min, an adsorption capacity of 4.71 mg/g was obtained, and it almost reached the adsorption equilibrium within 90 min.  相似文献   
95.
Novel hybridized multi-walled carbon nanotubes (CNTs), consisting of a unique hyperbranched polyaniline (HSiPA) and CNTs, were prepared. The interaction between HSiPA and CNTs was investigated by many techniques, and results show that there are strong ππ and electrostatic interactions between HSiPA and CNTs, so HSiPA can stack firmly onto the surface of CNTs to form a coating. Based on this, a new kind of ternary composites made up of hybridized CNTs and epoxy (EP) resin was prepared, the influence of the ratio of HSiPA to CNTs on the structure and properties of the HSiPA/CNT/EP composites was intensively studied. The percolation threshold of HSiPA/CNT/EP composites is very low (1.26 wt%); besides, with a suitable ratio of HSiPA to CNTs, the HSiPA/CNT/EP composite has much higher dielectric constant and lower dielectric loss than the CNT/EP composite with the same loading of CNTs. When the ratio of HSiPA to CNTs is 0.5:1, the dielectric constant and loss at 100 Hz of the resultant HSiPA/CNT0.5/EP composite are 711 and 1.53, about 7.1 and 4.3 × 10?3 times the corresponding value of CNT0.5/EP composite, respectively. In addition, compared with traditional CNT/EP composites, the HSiPA/CNT0.5/EP composites have different equivalent circuit models. These attractive results are attributed to unique structure of hybridized CNTs, and thus leading to greatly different structures between the CNT0.5/EP and HSiPA/CNT0.5/EP composites. This investigation reported herein suggests a new approach to prepare new CNTs and related composites with controllable dielectric properties.  相似文献   
96.
以氧、硫、硅、氮、磷等杂原子取代芴中sp3杂化的碳原子所形成的杂芴,不仅可以通过杂原子和π共轭体系间的相互作用有效地调控材料的电子结构,而且可以影响芴不同位置的修饰,从而得到了广泛关注。本文详细分析了1,8-位修饰杂芴的分子结构特点和光电特性,根据不同的杂原子分类论述了相关材料的合成方法和原理,综述了1,8-位修饰杂芴类材料在磷光主体材料、电致发光材料、太阳能电池材料以及有机配体材料等方面的应用进展,展望了其在有机光电材料方面的应用前景和发展趋势。  相似文献   
97.
In this article,we compute cohomology groups of the semisimple Lie conformal algebra S =Vir × Cur g with coefficients in its irreducible modules for a finite-dimensional simple Lie algebra g.  相似文献   
98.
Noncontact atomic force microscopy (AFM) has recently progressed tremendously in achieving atomic resolution imaging through the use of small oscillation amplitudes and well-defined modification of the tip apex. In particular, it has been shown that picking up simple inorganic molecules (such as CO) by the AFM tip leads to a well-defined tip apex and to enhanced image resolution. Here, we use the same approach to study the three-dimensional intermolecular interaction potential between two molecules and focus on the implications of using molecule-modified AFM tips for microscopy and force spectroscopy experiments. The flexibility of the CO at the tip apex complicates the measurement of the intermolecular interaction energy between two CO molecules. Our work establishes the physical limits of measuring intermolecular interactions with scanning probes.  相似文献   
99.
A GOx/Ag/TiO2 glucose biosensor was achieved by photoreducing Ag nanoparticles on TiO2 nanotube arrays (NTAs) following with adsorption of GOx. The morphology, structure, and element component of Ag/TiO2 NTAs were characterized by scanning electron microscope, transmission electron microscope, and X-ray diffraction. Ag nanoparticles were uniformly deposited on surface of TiO2 NTAs with average size of 15 nm and the size and distribution changed with the immersing time of TiO2 NTAs in AgNO3 aqueous solution. Electrochemical properties of Ag/TiO2 NTAs were characterized by cyclic voltammetry and amperometric detection of H2O2, revealing that TiO2 NTAs with immersing time of 30 min achieve the best electrochemical activity. The GOx/Ag/TiO2 NTAs biosensor with optimum conditions achieves a sensitivity of 0.39μA mM?1 cm?2 with liner range from 0.1 to 4 mM.  相似文献   
100.
离子色谱法同时测定大气降水中的5种阴离子   总被引:1,自引:0,他引:1  
以保留时间定性、峰面积外标法定量,建立了离子色谱同时测定大气降水中F–,Cl–,NO2–,NO3–,SO42–5种阴离子的分析方法。结果表明,5种阴离子标准曲线线性相关系数均大于0.999 8,检出限(3s/k)在0.000 3~0.006 6 mg/L之间。F–,Cl–,NO2–,NO3–,SO42–测定结果的相对标准偏差(n=10)分别为1.70%,2.46%,9.30%,0.73%,0.67%。用该方法对水样进行测定并进行加标回收试验,5种阴离子加标回收率在91.2%~102.7%之间。该方法灵敏度高,简便、快速,能满足大气降水中阴离子分析的要求。  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