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51.
Photocleavable and tunable thermoresponsive amphiphilic random copolymer: Self‐assembly into micelles,dye encapsulation,and triggered release
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Somdeb Jana Avijit Bose Anupam Saha Tarun K. Mandal 《Journal of polymer science. Part A, Polymer chemistry》2017,55(10):1714-1729
A double‐responsive amphiphilic random copolymer (P(OEtOxA)‐ran‐PNBA) composed of thermoresponsive poly(oligo(2‐ethyl‐2‐oxazoline)acrylate) (P(OEtOxA)) segments and photocleavable poly(2‐nitrobenzyl acrylate) (PNBA) segments is synthesized via combination of cationic ring‐opening polymerization (CROP) and reversible addition‐fragmentation chain transfer (RAFT) polymerization techniques. The P(OEtOxA)‐ran‐PNBA copolymer exhibits lower critical solution (LCST)‐type soluble‐to‐turbid phase transition in water with tunable cloud point (Tcp) with respect to chain length of P(OEtOxA) segment present. The photocleavage of PNBA segments by UV irradiation transforms amphiphilic P(OEtOxA)‐ran‐PNBA to fully hydrophilic P(OEtOxA)‐ran‐poly(acrylic acid) resulting in the appreciable increase of Tcp of copolymer in aqueous solution. Owing to the amphiphilic nature, the P(OEtOxA)‐ran‐PNBA copolymer molecules self‐assemble into well‐dispersed spherical micelles in water. There is a disruption of the copolymer micelles with UV light irradiation as well as shrinkage of micellar size with increasing temperature above the LCST of copolymer in solution. Finally, the encapsulation of hydrophobic guest molecule (nile red) into P(OEtOxA)‐ran‐PNBA copolymer micelles and thermo‐ and photo‐triggered release of nile red are demonstrated. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1714–1729 相似文献
52.
Azomethine ylides derived in situ from l ‐proline and aryl aldehydes underwent regioselective and stereoselective cycloadditions with diaryl cycloahexanone to form a series of spiro‐pyrrolizidine compounds. By using equimolar proportions of the reactants in DMF, only a single mono‐adduct, namely 6′‐arylidene‐1‐aryl‐3‐aryl‐spiro[pyrrolizidine‐2,2′‐cyclohexanone], was formed, the second double bond in the dipolarophile remaining unaffected. Structure elucidation was achieved by detailed spectroscopic analyses and XRD studies. Interesting solid‐state structural characteristics were revealed by XRD analysis. 相似文献
53.
Srinivasan Natarajan Sukhendu Manual Partha Mahata Vandavasi Koteswara Rao Padmini Ramaswamy Abhishek Banerjee Avijit Kumar Paul K. V. Ramya 《Journal of Chemical Sciences》2006,118(6):525-536
The preparation of inorganic compounds, exhibiting open-framework structures, by hydrothermal methods has been presented.
To illustrate the efficacy of this approach, few select examples encompassing a wide variety and diversity in the structures
have been provided. In all the cases, good quality single crystals were obtained, which were used for the elucidation of the
structure. In the first example, simple inorganic network compounds based on phosphite and arsenate are described. In the
second example, inorganic-organic hybrid compounds involving phosphite/arsenate along with oxalate units are presented. In
the third example, new coordination polymers with interesting structures are given. The examples presented are representative
of the type and variety of compounds one can prepare by careful choice of the reaction conditions. 相似文献
54.
Three‐Arm,Biotin‐Tagged Carbazole–Dicyanovinyl–Chlorambucil Conjugate: Simultaneous Tumor Targeting,Sensing, and Photoresponsive Anticancer Drug Delivery
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Yarra Venkatesh Dr. S. Karthik Y. Rajesh Prof. Mahitosh Mandal Dr. Avijit Jana Prof. N. D. Pradeep Singh 《化学:亚洲杂志》2016,11(24):3482-3486
The design, synthesis, and in vitro biological studies of a biotin–carbazole–dicyanovinyl–chlorambucil conjugate (Bio‐CBZ‐DCV‐CBL; 6 ) are reported. This conjugate ( 6 ) is a multifunctional single‐molecule appliance composed of a thiol‐sensor DCV functionality, a CBZ‐derived phototrigger as well as fluorescent reporter, and CBL as the anticancer drug, and Bio as the cancer‐targeting ligand. In conjugate 6 , the DCV bond undergoes a thiol–ene click reaction at pH<7 with intracellular thiols, thereby shutting down internal charge transfer between the donor CBZ and acceptor DCV units, resulting in a change of the fluorescence color from green to blue, and thereby, sensing the tumor microenvironment. Subsequent photoirradiation results in release of the anticancer drug CBL in a controlled manner. 相似文献
55.
Saha A Tiwary AS Mukherjee AK 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,71(3):835-840
4-Acetamidophenol (paracetamol) is shown to form charge transfer complex with 2,3-dichloro1,4-naphthoquinone in aqueous ethanol media exhibiting the unusual 2:1 (paracetamol:quinone) stoichiometry. The complexation enthalpy and entropy have been estimated from the formation constant (K) determined spectrophotometrically at five different temperatures. In aqueous ethanol mixtures of varying composition K increases with increasing dielectric constant of the medium. This has been rationalized by calculating the electronic charge distribution in paracetamol molecule and its conjugate base at the DFT/B3LYP/6-31++G(d,p) level. The theoretically calculated vertical ionization potential of paracetamol also agrees with reported experimental value. 相似文献
56.
57.
Avijit Hazra Mitchell T. Lee Justin F. Chiu Prof. Gojko Lalic 《Angewandte Chemie (International ed. in English)》2018,57(19):5492-5496
We have developed a photoinduced copper‐catalyzed alkylation of terminal alkynes with primary, secondary, or tertiary alkyl iodides as electrophiles. The reaction has a broad substrate scope and can be successfully performed in the presence of ester, nitrile, aryl halide, ketone, sulfonamide, epoxide, alcohol, and amide functional groups. The alkylation is promoted by blue light (λ≈450 nm) and proceeds at room temperature in the absence of any additional metal catalysts. The use of a terpyridine ligand is essential for the success of the reaction and is shown to prevent photoinduced copper‐catalyzed polymerization of the starting materials. 相似文献
58.
Avijit Khanra 《Operations Research Letters》2017,45(1):84-89
We study the impact of suboptimal decisions in the newsvendor model, one of the popular inventory models. We establish a lower bound for the deviation of inventory cost from its minimum, when the order quantity is suboptimal. Demonstration of the bound shows the model to be sensitive to suboptimal decisions. 相似文献
59.
Peptide‐poly(2‐(dimethylamino)ethyl methacrylate) conjugates: Synthesis and aqueous/nonaqueous self‐aggregation into nanostructures of dendritic and spherical morphologies
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Anupam Saha Somdeb Jana Avijit Bose Tarun K. Mandal 《Journal of polymer science. Part A, Polymer chemistry》2017,55(19):3286-3297
Peptide–polymer conjugate consisting of a sequence‐defined tripeptide and poly(2‐(dimethylamino)ethyl methacrylate) (PDMAEMA) is synthesized by a simple “grafting from” atom transfer radical polymerization (ATRP) approach. The ATRP of PDMAEMA using peptide‐macroinitiator and CuBr/1,1,4,7,10,10‐hexamethyltriethylenetetramine system in anisole follows pseudo first order kinetics up to a conversion of about 25% within a time span of 125 min. The attachment of peptide moiety at the end of PDMAEMA chain is confirmed from MALDI‐TOF‐MS and circular dichroism analyses. The self‐assembly of as‐synthesized peptide‐PDMAEMA conjugate in organic solvents leads to the formation of spherical nanoparticles as observed through FESEM. Peptide‐PDMAEMA conjugate become soluble in water due to the protonation of the pendent —N(CH3)2 moiety of DMAEMA group of the conjugate. Owing to the amphiphilic nature of the protonated conjugate (peptide‐PDMAEMAH), it also undergoes self‐aggregation in water into nanostructures of various morphologies such as dendrite, small sphere and large sphere at pHs of 2, 8, and 10, respectively. Peptide‐PDMAEMA‐IBu conjugate obtained by the post‐modification of —N(CH3)2 moiety of DMAEMA group of the conjugate with n‐butylbromide also undergoes self‐aggregation into dendritic nanostructures in water. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3286–3297 相似文献
60.
The moduli space of triples of the form (E,θ,s) are considered, where (E,θ) is a Higgs bundle on a fixed Riemann surface X, and s is a nonzero holomorphic section of E. Such a moduli space admits a natural map to the moduli space of Higgs bundles simply by forgetting s. If (Y,L) is the spectral data for the Higgs bundle (E,θ), then s defines a section of the line bundle L over Y. The divisor of this section gives a point of a Hilbert scheme, parametrizing 0-dimensional subschemes of the total space
of the canonical bundle K
X
, since Y is a curve on K
X
. The main result says that the pullback of the symplectic form on the moduli space of Higgs bundles to the moduli space of
triples coincides with the pullback of the natural symplectic form on the Hilbert scheme using
the map that sends any triple (E,θ,s) to the divisor of the corresponding section of the line bundle on the spectral curve.
Received: 15 January 2000 / Accepted: 25 March 2001 相似文献