全文获取类型
收费全文 | 234篇 |
免费 | 10篇 |
专业分类
化学 | 158篇 |
晶体学 | 2篇 |
力学 | 3篇 |
数学 | 19篇 |
物理学 | 62篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 8篇 |
2019年 | 6篇 |
2018年 | 7篇 |
2017年 | 5篇 |
2016年 | 11篇 |
2015年 | 7篇 |
2014年 | 4篇 |
2013年 | 16篇 |
2012年 | 10篇 |
2011年 | 17篇 |
2010年 | 20篇 |
2009年 | 12篇 |
2008年 | 20篇 |
2007年 | 12篇 |
2006年 | 22篇 |
2005年 | 7篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有244条查询结果,搜索用时 15 毫秒
51.
The novel (E,E)-dioxime 5,6:13,14-dibenzo-9,10-benzo(15-crown-5)-2,3-bis(hydroxyimino)-7,12-dioxo-1,4,8,11-tetraazacyclotetradecane (H2L) has been synthesized by the reaction of 4′,5′-diaminobenzo(15-crown-5) with N,N′-bis(2-carbomethoxyphenyl)diaminoglyoxime (1). Only mononuclear CoIII and RuII complexes with a metal/ligand ratio of 1:2 have been isolated. The cobalt(III) complex bridged with BF2+ is achieved with H-bonded cobalt(III) complex and borontrifluoride ethyl ether complex. The reaction of BF2 bridged cobalt(III) complex with bis(benzonitril)palladium(II) chloride gives a trinuclear complex. The structures of dioxime and its complexes are proposed according to elemental analyses, 1H and 13C-NMR, IR and mass spectral data. 相似文献
52.
Murat Çelik Cemalettin Alp M. Serdar Gültekin Metin Balci 《Tetrahedron letters》2006,47(22):3659-3663
1,2- and 1,3-Bis(trifluoroacetoxy) alcohols are easily obtained from the one-pot reaction of alkenes with phenyliodine(III) bis(trifluoroacetate) (PIFA) in the absence of any additive or catalyst. The products were converted into the corresponding diols by ammonolysis. The use of bicyclic alkenes has shown that rearranged 1,3-diacetoxy alcohols are mostly formed as the major products. 相似文献
53.
U. Tunca T. Erdogan G. Hizal 《Journal of polymer science. Part A, Polymer chemistry》2002,40(12):2025-2032
An asymmetric difunctional initiator 2‐phenyl‐2‐[(2,2,6,6 tetramethylpiperidino)oxy] ethyl 2‐bromo propanoate ( 1 ) was used for the synthesis of ABC‐type methyl methacrylate (MMA)‐tert‐butylacrylate (tBA)‐styrene (St) triblock copolymers via a combination of atom transfer radical polymerization (ATRP) and stable free‐radical polymerization (SFRP). The ATRP‐ATRP‐SFRP or SFRP‐ATRP‐ATRP route led to ABC‐type triblock copolymers with controlled molecular weight and moderate polydispersity (Mw/Mn < 1.35). The block copolymers were characterized by gel permeation chromatography and 1H NMR. The retaining chain‐end functionality and the applying halide exchange afforded high blocking efficiency as well as maintained control over entire routes. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2025–2032, 2002 相似文献
54.
Dipl.-Phys. Lena Scherthan Rouven F. Pfleger Dr. Hendrik Auerbach Dipl.-Phys. Tim Hochdörffer Dr. Juliusz A. Wolny Dr. Wenli Bi Dr. Jiyong Zhao Dr. Michael Y. Hu Dr. E. Ercan Alp Dr. Christopher E. Anson Prof. Rolf Diller Prof. Annie K. Powell Prof. Volker Schünemann 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(23):8902-8907
55.
Tuba Erdogan Eda Gungor Hakan Durmaz Gurkan Hizal Umit Tunca 《Journal of polymer science. Part A, Polymer chemistry》2006,44(4):1396-1403
We prepared a novel miktoarm star copolymer with an azobenzene unit at the core via combination of atom transfer radical polymerization (ATRP) and nitroxide‐mediated free radical polymerization (NMP) routes. For this purpose, first, mikto‐functional initiator, 3 , with tertiary bromide (for ATRP) and 2,2,6,6‐tetramethylpiperidin‐1‐yloxy (TEMPO) (for NMP) functionalities and an azobenzene moiety at the core was synthesized. The initiator 3 thus obtained was used in the subsequent living radical polymerization routes such as ATRP of MMA and NMP of St, respectively, to give A2B2 type miktoarm star copolymer, (PMMA)2‐(PSt)2 with an azobenzene unit at the core with controlled molecular weight and low polydispersity (Mw/Mn < 1.15). The photoresponsive properties of 3 and (PMMA)2‐(PSt)2 miktoarm star copolymer were investigated. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1396–1403, 2006 相似文献
56.
Humeyra Mert Umit Tunca Gurkan Hizal 《Journal of polymer science. Part A, Polymer chemistry》2006,44(20):5923-5932
The copper‐catalyzed living radical polymerization (LRP) of styrene (St) was carried out in the presence of thiophenol derivative such as sodium thiophenolate (PhSNa) or p‐methoxythiophenol as a reducing agent for Cu(II) by using either 1‐chloro‐1‐phenyl ethane or ethyl‐2‐bromoisobutyrate as an initiator and N,N,N′,N″,N″‐pentamethyldiethylenetriamine as ligand at 110 °C. Kinetic experiments were carried out to reveal the effect of PhSNa concentration on copper‐catalyzed LRP of St. This technique was successfully applied for the preparation of both chain‐extended polymer and block copolymer polystyrene‐b‐poly(methyl methacrylate). The obtained polymers were characterized using GPC, 1H‐NMR, and MALDI‐TOF measurements. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5923–5932, 2006 相似文献
57.
Aydan Dag Mehtap Aydin Hakan Durmaz Gurkan Hizal Umit Tunca 《Journal of polymer science. Part A, Polymer chemistry》2012,50(21):4476-4483
In this work, we used Diels–Alder click reaction for the preparation of various types of aliphatic polycarbonates (PCs). We first prepared a novel anthracene‐functionalized cyclic carbonate monomer, anthracen‐9‐ylmethyl 5‐methyl‐2‐oxo‐1,3‐dioxane‐5‐carboxylate (2), followed by ring‐opening polymerization of this monomer to prepare PC with pendant anthracene groups (PC‐anthracene) using 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU)/1‐(3,5‐bis(trifloromethyl)phenyl)‐3‐cyclohexylthiourea (TU) as the catalyst and benzyl alcohol as the initiator in CH2Cl2 at room temperature. Subsequently, the resulting PC‐anthracene (Mn,TDGPC = 6000 g/mol, Mw/Mn = 1.22) was grafted with a linear α‐furan protected‐maleimide terminated‐poly(methyl methacrylate) (PMMA‐MI) (Mn,GPC = 3100 g/mol, Mw/Mn = 1.31), or poly(ethylene glycol) (PEG‐MI) (Mn,GPC = 550 g/mol, Mw/Mn = 1.09), or a mixture of PMMA‐MI and PEG‐MI to yield well‐defined PC graft or hetero graft copolymers, PC‐g‐PMMA (Mn,TDGPC = 59000 g/mol, Mw/Mn = 1.22) or PC‐g‐PEG, or PC‐g‐(PMMA)‐co‐PC‐g‐(PEG) (Mn,TDGPC = 39900 g/mol, Mw/Mn = 1.16), respectively, using Diels–Alder click reaction in toluene at 110°C. The Diels–Alder grafting efficiencies were found to be over 97% using UV spectroscopy. Moreover, the structural analyses and the molecular weights of resulting graft copolymers were determined via 1H NMR and triple detection GPC (TD‐GPC), respectively. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
58.
59.
The São Paulo School of Advanced Sciences (ESPCA) on Recent Developments in Synchrotron Radiation was held July 13–24, 2015, at the Brazilian Synchrotron Light Laboratory (LNLS) in Campinas, Brazil. The school was attended by 96 students, 48 from Brazil and 48 from 17 different countries. A total of 27 different nationalities were represented in this 12-day school. In addition, 22 lecturers presented 34 talks. 相似文献
60.
Semanur Parlayan Aysel Başoğlu Yasemin Göbel Miraç Ocak Hakan Alp Halit Kantekin Ümmühan Ocak 《Journal of inclusion phenomena and macrocyclic chemistry》2010,67(3-4):451-460
A new 14-membered crown ether with nitrogen–sulfur donor atom carrying two anthryl groups was designed and synthesized by the reaction of the corresponding macrocyclic compound and 9-(chloromethyl) anthracene. The influence of metal cations such as Al3+, Zn2+, Fe2+, Fe3+, Co2+, Ni2+, Mn2+, Cu2+, Cd2+, Hg2+ and Pb2+ on the spectroscopic properties of the ligand was investigated in acetonitrile–dioxane solution (1/1) by means of absorption and emission spectrometry. The results of spectrophotometric titration experiments disclosed the complexation stoichiometry and complex stability constant of the novel ligand with Fe2+, Fe3+, Al3+, Cd2+, Cu2+, Zn2+, Pb2+ and Hg2+ cations. Absorption spectra show isobestic points in the spectrophotometric titration of these cations. The presence of excess of Al3+, Zn2+, Fe2+, Fe3+, Co2+, Ni2+, Mn2+, Cu2+, Cd2+, Hg2+ and Pb2+ cations caused an enhancement of anthryl fluorescence. Especially, the enhancement in case of the interaction of Hg2+ and Al3+ cations with the ligand was pronounced. 相似文献