全文获取类型
收费全文 | 506篇 |
免费 | 44篇 |
国内免费 | 79篇 |
专业分类
化学 | 531篇 |
力学 | 10篇 |
综合类 | 5篇 |
数学 | 20篇 |
物理学 | 63篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2014年 | 30篇 |
2013年 | 47篇 |
2012年 | 43篇 |
2011年 | 9篇 |
2010年 | 1篇 |
2009年 | 3篇 |
2008年 | 20篇 |
2007年 | 19篇 |
2006年 | 15篇 |
2005年 | 18篇 |
2004年 | 28篇 |
2003年 | 35篇 |
2002年 | 85篇 |
2001年 | 193篇 |
2000年 | 31篇 |
1999年 | 20篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 1篇 |
1995年 | 3篇 |
排序方式: 共有629条查询结果,搜索用时 203 毫秒
621.
Xiao Yan WANG Yi CHEN* Center for Molecular Science Institute of Chemistry Chinese Academy of Sciences Beijing 《中国化学快报》2000,11(12)
Precolumn derivatization is the most widely used means to overcome the detection problem in capillary electrophoresis. However most of the adopted reactions in carbohydrate labeling are time-consuming and not very selective, leading to lots of byproducts produced. We have thus tried to explored hydrazino-containing reagents which have been applied to TLC1,2 and HPLC2~5 with quite successfulness. Perez and Colón6 have also reported that dansylhydrazine can be used in CE-LIF of sugars. Th… 相似文献
622.
Guang Yue BAI Hai Ke YAN* Institute of Chemistry the Chinese Academy of Sciences Beijing 《中国化学快报》2000,11(12)
Gemini surfactants, as a new generation of surfactants in 1990's1, are the surfactants with two polar groups and two alkyl chains connected with a spacer. The most widely studied gemini surfactants are as follows: [CmH2m+1N (CH3)2- (CH2)S -N (CH3 )2CmH2m+1] Br2, or Cm-CS-Cm(2Br -where Cs stands for its spacer. Studies on their interesting physico chemical properties2,3 have made much progress, predicting that the repulsive interaction between the two head groups, hydrophobic interactio… 相似文献
623.
1 INTRODUCTIONSulfoxideisknowntoformcoordinationcompoundswithLanthanide(Ⅲ)andtheirsyntheses,propertiesandvariousphysicalcharacteristicshavebeenreport-ed〔1~9〕.However,therearesomanydifficultyinpreparingthekindoflanthanidecomplexesbecausetheanionsuseda… 相似文献
624.
1 INTRODUCTIONThe coordination chemistry oftransition metalcomplexeshasbecomeofremark able interestin recentyears.Sotoftetal.reported the structure of Ni( CH3CN) 6·Zn Cl4 〔1〕.Recently,Shyu etal.reported the structure of〔 Ni( bipy) 3〕〔 Fe( CN) 5 ( NO)〕· 3 H2 O〔2〕.Herein we reportthe structure oftitle complex〔 Ni( bipy) 3〕〔 Zn Cl4 〕 which issimilarto theformertwo complexes.Itisvery interesting to synthesizebimetallic compoundsfor both theoreticalstudy and practicalapp… 相似文献
625.
三甲川菁染料敏化TiO2纳米
结构电极的光电化学 总被引:1,自引:0,他引:1
The
photoelectrochemical behaviors of the TiO2 nanostructured porous film
sensitized by cyanine dye were investigated in this paper.The results showed that the
excitaed state level matched the conduction band edge of TiO2
nanoparticle.Therefore the sensitization of the dye can increase the photocurrent
intensity of the TiO2 nanostructured electrode obviously and results in a
red-shift of optical absorption from the ultra-violet region to the visible.As a
result,the light-to-electricity conversion efficiency was improved evidently,the maximum
value of IPCE has reached 12.1%. 相似文献
626.
ZHENG Yue qing * 《高等学校化学研究》1999,(3)
IntroductionPreviously,wereportedthecrystalstructureofK2[Ni(CO3)2(H2O)4][1],whichcrystallizedinthebaylissitetypestructureandwasfoundtobeisostructuralwithK2[Co(CO3)2(H2O)4][2]andK2Mg(CO3)2·4H2O[3].Inordertosystematicallyinvestigatetheoccurrenceoftheco… 相似文献
627.
IntroductionAmrinon,asyntheticbipyridinederivative,nonglycosideandnoncatecholaminecar-diotonicstimulant,iscurrentlyusedinthetreatmentoftheheartfailureandforcardiovascu-larsupportinpediatricpatients.Itpossessespotentcardiacandbloodvesselspreadingef-fe… 相似文献
628.
1 INTRODUCTIONRecently,anumberofderivativesofbenzothiazepinehavebeenpreparedandstudiedfortheirpharmacologicalactivities〔15〕.Inourpreviouswork,wehaveincorporatedtheβlactamringinto1,5benzothiazepinebyreactionof1,5benzothiazepinewithsomeacylchlorid… 相似文献
629.
Weinan E~* Jianfeng LU~ 《数学年刊B辑(英文版)》2007,28(6):665-676
The authors consider the simplest quantum mechanics model of solids,the tight binding model,and prove that in the continuum limit,the energy of tight binding model converges to that of the continuum elasticity model obtained using Cauchy-Born rule.The technique in this paper is based mainly on spectral perturbation theory for large matrices. 相似文献