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141.
Anna Maria Raspolli Galletti Guido Pampaloni Aldo D'Alessio Yogesh Patil Filippo Renili Simone Giaiacopi 《Macromolecular rapid communications》2009,30(20):1762-1768
Ring‐opening metathesis polymerization (ROMP) of norbornene catalyzed by niobium(V) N,N‐dialkylcarbamates Nb(O2CNR2)5, R = Et ( 1 ), Me ( 2 ) was studied in the presence of methylaluminoxane (MAO) as a cocatalyst. These novel catalytic systems resulted very active in chlorobenzene: 1 in the presence of methylaluminoxane catalyzes the ROMP of norbornene with the highest activity (29 000 kg of polymer/mol of catalyst × hour) never reported up to now for niobium catalysts. The high productivity appears particularly attractive considering that these precursors are rather cheap and easy to synthesize and to handle. Polynorbornenes were characterized by FT‐IR and NMR spectroscopies and by DSC calorimetry. A new FT‐IR method for the swift determination of the cis/trans content of the polymer is presented.
142.
Xiaohui He Yueman Liu Lu Chen Yiwang Chen Defu Chen 《Journal of polymer science. Part A, Polymer chemistry》2012,50(22):4695-4704
A serial of late transition metal complexes, which bearing Benzocyclohexane–ketoarylimine ligand and named as Mt(benzocyclohexane–ketoarylimino)2 {Mt(bchkai)2: Mt=Ni or Pd; bchkai=C10H8(O)CN(Ar)CH3; Ar=naphthyl or fluoryl}, have been synthesized and characterized. The molecular structures of the ligands and nickel complex have been confirmed by X‐ray single‐crystal analyses. The nickel complexes exhibited very high activity up to 2.7 × 105 gpolymer/molNi·h and palladium complexes showed high activity up to 2.3 × 105 gpolymer/molPd·h for norbornene (NB) homo‐polymerization with tris(pentafluorophenyl)borane as cocatalyst. The four complexes were effective for copolymerization of NB and 5‐norbornene‐2‐carboxylic acid methyl ester (NB‐COOCH3) in relatively high activities (0.1–2.4 × 105 gpolymer/molMt·h) and produced the addition‐type copolymers with relatively high molecular weights (0.5 × 105–1.2 × 105 g/mol) as well as narrow molecular weight distributions (PDI < 2 for all polymers). Influences of the metals and comonomer feed content on the polymerization activity as well as on the incorporation rates (20.9–42.6%) were investigated. The achieved NB/NB‐COOCH3 copolymers were confirmed to be noncrystalline, exhibited good thermal stability (Td > 400°C) and showed good solubility in common organic solvents. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
143.
Anne‐Claire Le Meur Cyril Aymonier Valérie Heroguez 《Journal of polymer science. Part A, Polymer chemistry》2012,50(9):1746-1754
This article proposes the first report on the synthesis of nanometric crosslinked polynorbornene particles by ring‐opening metathesis polymerization in dispersion using ruthenium‐based complex (PCy3)2Cl2Ru?CHPh as initiator. Stable but raspberry‐shaped particles were obtained. In this study, a particular attention was paid to the influence of the crosslinker nature and addition mode on reaction kinetics and morphology of the latex particles. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
144.
Yuka Sakurai Dr. Yohei Ogiwara Prof. Dr. Norio Sakai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(57):12972-12977
A palladium-catalyzed annulation of acyl fluorides with norbornene is described. This study reports the first example of an annulation of acyl fluorides in the presence of a transition-metal catalyst. Polycyclic ketones are obtained from the cleavage of the C−F and C−H bonds of the acyl fluoride and the rearrangement of the carbonyl moiety by decarbonylation and CO reinsertion. 相似文献
145.
Anna Maria Raspolli Galletti Mohammad Hayatifar 《Journal of polymer science. Part A, Polymer chemistry》2012,50(21):4459-4464
Highly active, cheap, and easy to synthesize catalytic systems, obtained in situ by the oxidative addition of salicylaldimine ligands to bis(1,5‐cyclooctadiene)nickel(0) and activated by methylaluminoxane (MAO), are now reported for the vinyl polymerization of norbornene. Their activity resulted mainly influenced by the nature of the substituents present both on the phenolate moiety and on the N‐aryl ring as well as the content of free trimethylaluminum (TMA) present in the commercial MAO. In particular, the maximum activity, up to about 78,000 kg polynorbornene/mol Ni × h, was ascertained when 3,5‐dinitro‐N‐(2,6‐diisopropylphenyl)salicylaldimine ligand was adopted in conjunction with Ni(cod)2 and TMA‐depleted MAO. This remarkable performance, to the best of our knowledge, the highest never reported working in toluene instead of chlorinated aromatics, was reached adopting this more sustainable reaction medium. The influence of the main reaction parameters such as reaction time, temperature, monomer/Ni, and Al/Ni molar ratios on the catalytic performances and polymer characteristics was studied as well. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
146.
Gwang‐Su Byun Sang Youl Kim Iwhan Cho 《Journal of polymer science. Part A, Polymer chemistry》2006,44(3):1263-1270
(?)‐(1S,2R)‐Norbornene‐2‐carboxylic acid alkyl esters (alkyl = Me, Bz, L ‐menthyl, or D ‐menthyl) were successfully prepared by the Diels–Alder reaction of cyclopentadiene with (R)‐(?)‐pantolactone‐O‐yl acrylate followed by epimerization and column chromatography. The enantiomeric excess was 99.9%. These monomers were polymerized by Pd(II)‐based catalysts, and high yields of the polymers were obtained. The methyl ester gave an optically active polymer of high optical rotation (monomer [α]D = ?24.7, polymer [α]D = ?98.5). This high rotation value of the polymer was attributed to the isotactic chain regulation of the polymer. This high rotation was not observed with methyl esters prepared by the transesterification of menthyl esters. The stereoregular polymer exhibited notable resonance peaks at 39 ppm in 13C NMR spectra. No crystallinity was observed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1263–1270, 2006 相似文献
147.
The reaction of the lithium salt of backbone fluorinated β‐diketiminate ligands, ArNC(CF3)CHC(CF3) NArLi, with trans‐[NiCl(Ph)(PPh3)2] gives nickel (II) complexes, ArNC(CF3)CHC(CF3)NAr(Ph) (PPh3)Ni (Ar = 2, 6‐Me2C6H3: 1 ; 2, 6‐iPr2C6H3: 2 ). When activated by methylaluminoxane (MAO), both complexes polymerize norbornene rapidly via a vinyl‐type polymerization mechanism. Treatment of nickel complex 1 with oxygen gives rise to intramolecular aerobic hydroxylation. The oxygenated species 3 was characterized by X‐ray crystallography. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
148.
Haiyang Gao Yan Chen Fangming Zhu Qing Wu 《Journal of polymer science. Part A, Polymer chemistry》2006,44(18):5237-5246
Copolymerizations of norbornene with styrene were carried out with a catalytic system of anilido–imino nickel complex (ArN?CHC6H4NAr)NiBr (Ar = 2,6‐dimethylphenyl) and methylaluminoxane in toluene. The influence of the comonomer feed content and polymerization temperature on the conversion and composition of the copolymers with (ArN?CHC6H4NAr)NiBr/methylaluminoxane was investigated. An increase in the initial styrene feed content led to an increase in the incorporated styrene content of the resulting copolymer. The determination of the reactivity ratios showed a much high reactivity for norbornene (reactivity ratio for styrene = 0.26, reactivity ratio for norbornene = 20.78), which was consistent with a coordination mechanism. NMR analysis of the end groups further confirmed that the chain was initiated through a styrene secondary insertion or a norbornene insertion into Ni? H and terminated through β‐H elimination from an inserted styrene unit. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5237–5246, 2006 相似文献
149.
Kinetics and mechanism of the thermal degradation for the synthesis of poly(norbornene sulfone)s by two different polymerization methods 下载免费PDF全文
The recent development of sulfur dioxide (SO2) polymerization has seen a renaissance in its chemistry, especially poly(olefin sulfone)s from the copolymerization of SO2, and unsaturated hydrocarbons can be found to have many applications, including transient electronic packaging, drug delivery, and electron beam‐resistant materials. In this work, a type of functional poly(norbornene sulfone) was synthesized via two different polymerization methods. Aiming to understanding the effects of different polymerization methods on poly(olefin sulfone)s and gain further understanding on the kinetics of poly(olefin sulfone)s's thermal instability, we investigated their detailed thermal degradation behaviors using thermogravimetry and analyzed the resultant kinetics in accordance with three kinetic models. The results supported the conclusion that although the poly(norbornene sulfone)s obtained have different activation energy, the thermal degradation kinetics are the same and also obey the Dn type. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
150.
Kaiti Wang Yiwang Chen Xiaohui He Yueman Liu Weihua Zhou 《Journal of polymer science. Part A, Polymer chemistry》2011,49(15):3304-3313
Two complexes Mt{C10H8(O)C[N(C6H5)]CH3}2 [Mt = Ni(II); Mt = Pd(II)] were synthesized, and the solid‐state structures of the complexes have been determined by single‐crystal X‐ray diffractions. Homopolymerization of norbornene (NB) and copolymerization of NB and 5‐norbornene‐2‐yl acetate (NB‐OCOCH3) were carried out in toluene with both the two complexes mentioned above in combination with B(C6F5)3. Both the catalytic systems exhibited high activity toward the homopolymerization of NB (as high as 2.7 × 105 gpolymer/molNi h, for Ni(II)/B(C6F5)3 and 2.1 × 105 gpolymer/molPd h for Pd(II)/B(C6F5)3, respectively.). Although the Pd(II)/B(C6F5)3 shows very lower activity toward the copolymerization of NB with NB‐OCOCH3, Ni(II)/B(C6F5)3 shows a high activity and produces the addition‐type copolymer with relatively high molecular weights (MWs; 1.80–2.79 × 105 g/mol) as well as narrow MW distribution (1.89–2.30). The NB‐OCOCH3 content in the copolymers can be controlled up to 5.8–12.0% by varying the comonomer feed ratios from 10 to 50%. The copolymers exhibited high transparency, high glass transition temperature (Tg > 263.9 °C), better solubility, and mechanical properties compared with the homopolymer of NB. The reactivity ratios of the two monomers were determined to be rNB‐OCOMe = 0.08, rNB = 7.94 for Ni(II)/B(C6F5)3 system, and rNB‐OCOMe = 0.07, rNB = 6.49, for Pd(II)/B(C6F5)3 system by the Kelen‐Tüdõs method. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献