全文获取类型
收费全文 | 508篇 |
免费 | 47篇 |
国内免费 | 84篇 |
专业分类
化学 | 536篇 |
力学 | 7篇 |
综合类 | 8篇 |
数学 | 21篇 |
物理学 | 67篇 |
出版年
2020年 | 1篇 |
2019年 | 1篇 |
2016年 | 1篇 |
2014年 | 29篇 |
2013年 | 47篇 |
2012年 | 44篇 |
2011年 | 8篇 |
2010年 | 1篇 |
2009年 | 5篇 |
2008年 | 21篇 |
2007年 | 20篇 |
2006年 | 20篇 |
2005年 | 18篇 |
2004年 | 29篇 |
2003年 | 35篇 |
2002年 | 86篇 |
2001年 | 194篇 |
2000年 | 34篇 |
1999年 | 21篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
排序方式: 共有639条查询结果,搜索用时 15 毫秒
101.
和频振动光谱(SFG-VS)研究中由基团在界面上取向所引起的光谱增强或相消的干涉现象为研究分子在界面上的绝对取向提供了一种直接的测量方法. 这一方法比SFG实验中复杂的相位测量方法更为直接和简单可行. 以在空气/水界面取向已知的对羟基苯腈(PCP)分子的氰基(-CN)基团为相位参考来获得3,5-二甲基对羟基苯腈(35DMHBN)和2,6-二甲基对羟基苯腈(26DMHBN)分子在空气/水界面的取向信息. 通过对这三种分子的水溶液和它们两两混合溶液界面上-CN基团和频振动光谱强度的比较,发现在空气/水界面的3 相似文献
102.
CHEN Rongsheng * LIAO Yanbiao 《Chinese Journal of Lasers》2001,10(3):195
Asweknow ,asinglemodefibercouplerisasimplebutveryimportantfiberopticdevice ,whichcanbeusedincommunicationandsensors.Usingsinglemodeopticalfiberdevices,wecanfabricateseveralacoustic opticdevices ,suchasfrequencyshifters ,modulatorsandtunablefilters .Several… 相似文献
103.
YANG Hong-li * VAULTIER MichelSynthèse et Electrosynthèse Organiques UMR CNRS Université de Rennes Campus de Beaulieu Avenue du Général Leclerc RENNES CEDEX France 《高等学校化学研究》2002,18(4):414-418
IntroductionGrubbs catalyst bis(tricyclohexylphosphine)benzylidene ruthenium( ) dichloride1 can be usedin a variety of ring- closing metathesis (RCM )reactions,cross metathesis(CM) reactions andring- opening metathesis polymerization(ROMP) [1— 4 ] .It remains metathetically active inthe presence of a variety of functional groups,suchas carbonyls,alcohols,and amides[1] .The use ofcatalyst1 in the synthesis has drawn more andmore attention[5— 13] . However,this catalyst is veryexpensive,an… 相似文献
104.
Cigang Xu Emmanuel Flahaut Sam R. Bailey Gareth Brown Jeremy Sloan Karl S. Coleman V. Clifford Williams Malcolm L. H. Green * . Inorganic Chemistry Laboratory University of Oxford Oxford OX QR UK 《高等学校化学研究》2002,18(2):130-132
IntroductionSingle walledcarbonnanotubes(SWNTs)havebeensynthesisedbyusingvariousmethods[1— 3] andthechemicalvapourdeposition (CVD )methodhasbeenconsideredasa promisingmethodto produceSWNTsonanindustrialscale[3— 5] .However ,alltheSWNT productssynthesisedtodateco… 相似文献
105.
Jian Liang YE Xing Wang ZHOU Zhong CHEN* Zhi Wei CHEN Pei Qiang HUANG* Department of Chemistry Department of Biology Xiamen University Xiamen 《中国化学快报》2001,(11)
K3[VO(O2)2(C2O4)]2H2O, (abbr. BpV (ox)) pertains to peroxovanadium (abbr. pV) complexes, which have been attracted considerable attention nowadays, since they are inhibitors of tyrosine phosphatase and may be developed into a new kind of drugs for the treatment of diabetes1. According to the evidence on water-biperoxovanadium, the molecular mechanism of insulin-like effects of pV involves in irreversibly oxidizing the catalytic cysteine at the active site of the target enzyme2,3. However… 相似文献
106.
Recently, the studies on the interaction of DNA with small molecules have been attracting much interest1-6. These researches not only gave the important information about thermodynamics and kinetics, but also can prompt the combination between the electrode substances and biomacromolecule with super catalysis and sensor character. It is of great significance in understanding energy conversion and metabolism in live body, biomolecular structure, various physical and chemical characters for e… 相似文献
107.
Neng Dong WANG Liu Min CHEN Sheng JIN= Xiu ZHANG Jia Hua CHEN* The Key Lab of Bioorganic Chemistry Molecular Engineering Ministry of Education China College of Chemistry Molecular Engineering Peking University Beijing 《中国化学快报》2001,(10)
The drug overdose and addiction is a serious international problem. Therefore developing a rapid, accurate, convenient and cheap method for detecting morphine in urea is useful and necessary, especially for investigation of epidemiology, identification of medical jurisprudence and determination of drug addict etc. There are many compounds that are similar to morphine in chemical structure and tend to have cross-reaction with the anti-morphine antibody. In order to reduce the cross reaction a… 相似文献
108.
Jian Guo DENG Xiao Bin DING Yu Xing PENG* Albert S. C. CHAN* Chengdu Institute of Organic Chemistry Chinese Academy of Sciences Chengdu Open Laboratory of Chirotechnology Department of Applied Biology Chemical Technology 《中国化学快报》2001,(11)
Among various conducting polymers, polyaniline (PANI) is a unique and promising candidate for practical applications because it is not only highly stable in air and in some solvents, but also exhibits dramatic changes in its electronic structure and physical properties in protoactivate state1,2,3. The carbon nanotubes (CNTs) have been proven to possess exotic properties, such as high mechanical strength, flexibility and electric conductivity. The study of carbon-based nanostructures and ma… 相似文献
109.
Jian Feng GE Li Fen ZHANG Zong Xuan SHEN Ya Wen ZHANG* Department of Chemistry Chemical Engineering Suzhou University Suzhou Department of Material Engineering Suzhou University Suzhou 《中国化学快报》2001,(7)
Mercaptoalcohols are a rare class of natural products. Some optically active mercaptoalcohols have been used as catalysts in asymmetric reduction of prochiral Ketone1,2. In this letter, we report the synthesis of a new optically active (-mercaptoalcohols, (R)-1,1-diphenyl-2-mercapto-3-methyl-1-butanol 7, from L- valine.Our first attempt is showed in Scheme 1. According to literature's method L-valine was converted to (S)-2-Hydroxy-3-methylbutanoic acid 21,2. 2 was treated with MeOH/SOCl2… 相似文献
110.
Sai Jing ZHENG Xiang Qin LIN* Department of Chemistry University of Science Technology of China Hefei 《中国化学快报》2001,(7)
Interactions of DNA with various molecules are interesting because of its importance in gene expression process of living cells. Several models for the interaction between DNA and some small molecules have been proposed1-4. We are interested in the possibility of the interaction between DNA/RNA and neurotransmitters, such as dopamine and epinephrine, because these species are very important substances for keeping normal physiological functions of brain and neuro system. However, no report… 相似文献