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   208篇
  免费   34篇
  国内免费   41篇
化学   81篇
晶体学   25篇
力学   5篇
数学   74篇
物理学   98篇
  2024年   6篇
  2023年   5篇
  2022年   12篇
  2021年   8篇
  2020年   11篇
  2019年   7篇
  2018年   9篇
  2017年   8篇
  2016年   8篇
  2015年   16篇
  2014年   9篇
  2013年   20篇
  2012年   32篇
  2011年   42篇
  2010年   28篇
  2009年   14篇
  2008年   7篇
  2007年   8篇
  2006年   3篇
  2005年   3篇
  2004年   3篇
  2003年   2篇
  2001年   5篇
  2000年   4篇
  1999年   1篇
  1998年   2篇
  1996年   1篇
  1993年   1篇
  1991年   1篇
  1990年   2篇
  1988年   1篇
  1987年   2篇
  1986年   2篇
排序方式: 共有283条查询结果,搜索用时 15 毫秒
1.
Crystallography Reports - A zinc coordination polymer with V-shaped ligands, [L1Zn(npa)]n (L1 = bis(4-(2'-methylimidazol)phenyl)sulfone, H2npa = 4-nitrophthalic acid) has been synthesized under...  相似文献   
2.
Crystallography Reports - Two mononuclear tetra-coordinated cobalt(II) complexes with molecular formula [Co(L)2(SCN)2] (L = 1-methylbenzimidazole (mbim), 1; L = 1-methyl-2-aminobenzimidazole...  相似文献   
3.
Crystallography Reports - A cobalt coordination polymer, {[Co(L1)2(H2O)2] · (HCOO)2 · H2O}n, where L1 is a bis(4-(1H-imidazol-1-yl)phenyl)methanone, has been synthesized and characterized...  相似文献   
4.
Catechol adsorbed on TiO2 is one of the simplest models to explore the relevant properties of dye-sensitized solar cells. However, the effects of water and defects on the electronic levels and the excitonic properties of the catechol/TiO2 interface have been rarely explored. Here, we investigate four catechol/TiO2 interfaces aiming to study the influence of coverage, water, and defects on the electronic levels and the excitonic properties of the catechol/TiO2 interface through the first-principles many-body Green's function theory. We find that the adsorption of catechol on the rutile (110) surface increases the energies of both the TiO2 valence band maximum and conduction band minimum by approximately 0.7 eV. The increasing coverage and the presence of water can reduce the optical absorption of charge-transfer excitons with maximum oscillator strength. Regarding the reduced hydroxylated TiO2 substrate, the conduction band minimum decreases greatly, resulting in a sub-bandgap of 2.51 eV. The exciton distributions in the four investigated interfaces can spread across several unit cells, especially for the hydroxylated TiO2 substrate. Although the hydroxylated TiO2 substrate leads to a lower open-circuit voltage, it may increase the separation between photogenerated electrons and holes and may therefore be beneficial for improving the photovoltaic efficiency by controlling its concentration. Our results may provide guidance for the design of highly efficient solar cells in future.  相似文献   
5.
Russian Journal of Coordination Chemistry - Two 2D cobalt complexes, namely {[(Bipmo)2Co2(Ipa)2](DMF)]·2.25H2O}n (I), {[(Bipmo)-Co(Ipa)]·2H2O}n (II), have been constructed solvothermally...  相似文献   
6.
7.
《结构化学》2020,39(5):873-883
Food waste orange peel was employed as a raw material to prepare biomass adsorbent to solve the indoor Total Volatile Organic Compounds(TVOC). The preparation process of orange peel treated with KOH was optimized by the quadratic regression orthogonal rotation, and the regression model and optimal processing conditions were obtained. The structure of the adsorbent was characterized by BET, SEM, TEM, EDS, XRD and FTIR analysis. The adsorption properties and desorption regeneration were discussed. The results showed the maximal removal rate Ymax was 9.4824% when KOH concentration was 0.3 mol/L, the soaking time of KOH was 26 h and that of HCl was 2.89 h. The best single factor condition was the adsorbent with 40 mesh size and 6.0 g. The adsorption of modified orange peel on TVOC conformed to the Freundlich models, which was more inclined to multi-layer active site adsorption. The adsorption law followed the quasi-second-order kinetic model(R~2 = 0.955), indicating the adsorption was a physico-chemical mixture but controlled by physical adsorption and it was a spontaneous endothermic process. The modified orange peel exposed more sites and had stronger chemical groups, which were beneficial to adsorption. The adsorbent has a significantly better TVOC removal rate than other materials at 1% level, that is, modified orange peel diatomite activated carbon bamboo charcoal macroporous resin. In addition, it had good recycling and regeneration capacity.  相似文献   
8.
水热条件下,环境友好的K2[Ni(CN)4]能缓慢水解形成cis-[Ni(CN)2(H2O)4]单元和氰基配体,并进一步与金属铜(Ⅰ)原子组装形成异金属的五边形带。这些五边形带通过亲铜聚集作用形成二维有色的超分子多形体[(CuCN)2Ni(CN)2(H2O)4](12)。研究发现,低温条件下形成了密集态的深蓝色的化合物1,然而高温反应条件形成疏松态的紫色化合物2,这一现象与高温高压的反应条件形成密集态的物质这一规律相违背。结构的进一步分析发现五边形环尺寸的微小改变和二维超分子层间距离的差异是引起这一反常的原因。除此之外,这两个新的化合物也是少见的由亲铜性聚集作用诱导的着色异常的多形体的例子,显示了从深蓝色到紫色的颜色改变。磁性研究证实了平面正方形的[Ni(CN)4]2-中的金属镍(Ⅱ)转换成了有着基态自旋S=1的八面体配位几何中心。  相似文献   
9.
《Tetrahedron: Asymmetry》2005,16(20):3385-3393
The recently reported diastereoselective three-component reaction for the synthesis of chiral propargylamines was used for a new stereoselective synthesis of JOSIPHOS-type ligands 2ad. The present synthesis gives the desired diphosphines in good yields without the need of resolution. Ligands 2ad were applied to the rhodium-catalyzed hydroboration of styrene.  相似文献   
10.
Qichang Jiang  Yanli Su  Xuanmang Ji 《Optik》2011,122(6):490-493
We investigate numerically the effects of higher-order space-charge field on the self-deflection of bright photovoltaic spatial solitons in two-photon photovoltaic photorefractive crystals under steady-state conditions. The expression for an induced space-charge electric field, including higher-order space-charge field terms is obtained. The dynamical evolution equation is built in which the effects that arise from these higher-order terms are considered. Numerical results indicate that bright photovoltaic solitons can bend towards both the same direction as the crystal's c-axis and the opposite direction, respectively. Specifically, self-deflection cannot occur for bright photovoltaic solitons if the strength of the photovoltaic field and the intensity of the input beam are appropriately selected. Relevant examples are provided.  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