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111.
Leszek Pazderski Andrzej Surdykowski Magorzata Pazderska-Szabowicz Jerzy Sitkowski Lech Kozerski Bohdan Kamieski Edward Szyk 《Central European Journal of Chemistry》2008,6(1):55-64
trans-[Co(py)4Cl2]Cl·6H2O, mer-[Co(py)3Cl3] and mer-[Co(py)3(CO3)Cl] were studied by UV-Vis, far-IR and 1H, 13C, 15N NMR. The formation of Co-N bonds lead to variable in sign and magnitude changes of 1H NMR chemical shifts, heavily dependent on proton position, coordination sphere geometry and character of auxiliary ligands.
13C nuclei were deshielded upon Co(III) coordination, while 15N NMR studies exhibited ca. 85–110 ppm shielding effects (ca. 15–25 ppm more expressed for nitrogens trans to N than trans to Cl or O). 13C and 15N CPMAS spectra revealed a slight inequivalency of formally identical Co-py bonds in trans-[Co(py)4Cl2]Cl·6H2O and mer-[Co(py)3Cl3], suggesting for the latter complex an existence of distortion isomers. In chloroform, a spontaneous trans-[Co(py)4Cl2]Cl → mer-[Co(py)3Cl3] + py reaction was monitored by 1H NMR and UV-Vis. This process of py → Cl substitution allowed the design of a more convenient and efficient method of mer-[Co(py)3Cl3] preparation.
相似文献
112.
Lapinski L Reva I Nowak MJ Fausto R 《Physical chemistry chemical physics : PCCP》2011,13(20):9676-9684
Photoisomerization processes involving five isomers of cytosine were induced by narrowband tunable UV irradiation of matrix-isolated monomers of the compound. Irradiation of an argon matrix containing cytosine monomers with UV λ = 313 nm laser light resulted in syn?anti photoisomerizations between the two imino-oxo forms, whereas the substantially more populated amino-hydroxy and amino-oxo forms stayed intact. Subsequent irradiation with shorter-wavelength UV λ = 311 nm laser light led to two concomitant phototautomeric processes consuming the amino-oxo isomer: (i) an oxo → hydroxy hydrogen-atom transfer photoprocess converting the amino-oxo form into the amino-hydroxy tautomer; (ii) amino → imino hydrogen-atom transfer converting the amino-oxo form into the imino-oxo isomers. The UV-induced phototransformations, together with mutual conversions of the two amino-hydroxy conformers induced by irradiation with narrowband NIR light, allowed positive detection and identification of the five isomeric forms of monomeric cytosine. This is the first experimental observation of all five low-energy isomers of cytosine. 相似文献
113.
Pazderski L Pawlak T Sitkowski J Kozerski L Szlyk E 《Magnetic resonance in chemistry : MRC》2011,49(5):237-241
(1)H, (13)C and (15)N NMR studies of iron(II), ruthenium(II) and osmium(II) bis-chelated cationic complexes with 2,2':6',2″-terpyridine ([M(terpy)(2) ](2+) ; M = Fe, Ru, Os) were performed. Significant shielding of nitrogen-adjacent H(6) and deshielding of H(3'), H(4') protons were observed, both effects being mostly expressed for Fe(II) compounds. The metal-bonded nitrogens were shielded, this effect being much larger for the outer N(1), N(1″) than the inner N(1') atoms, and enhanced in the Fe(II) → Ru(II) → Os(II) series. 相似文献
114.
Teobald Kupka Michał Stachów Leszek Stobiński Jakub Kaminský 《Magnetic resonance in chemistry : MRC》2013,51(8):463-468
The 3He nuclear magnetic shieldings were calculated for single helium atom, its dimer, simple models of fullerene cages (He@Cn), and single wall carbon nanotubes. The performances of several levels of theory (HF, MP2, DFT‐VSXC, CCSD, CCSD(T), and CCSDT) were tested. Two sets of polarization‐consistent basis sets were used (pcS‐n and aug‐pcS‐n), and an estimate of 3He nuclear magnetic shieldings in the complete basis set limit using a two‐parameter fit was established. Theoretical 3He results reproduced accurately previously reported theoretical values for helium gas, dimer, and helium probe inside several fullerene cages. Excellent agreement with experimental values was achieved. 3He nuclear magnetic shieldings of single helium atom approaching various points of benzene ring were tested, and an impact of 3He confinement within fullerene cages of different size on the 3He chemical shift was determined. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
115.
Elwira Chrobak Andrzej Maślankiewicz Magdalena Chyćko Leszek Skrzypek Małgorzata Szmielew Maria J. Maślankiewicz 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):1208-1225
Abstract Treatment of 1,4-dithiino[2,3-c:5,6-c′]diquinoline (a thioquinanthrene) (1a) with an excess of nitrating mixture (0 °C, 14 days) led to a mixture of mono- and dinitrothioquinanthrene 7-oxides 2b–e and 2f–h. This mixture was: (i) reduced to a mixture of mono- and dinitrothioquinanthrenes 1b– e, or (ii) oxidatively chlorinated with a gaseous chlorine/80% acetic acid/hydrochloric acid system to a mixture of 4-chloro-3-chlorosulfonylquinoline 3a and its 5- and 8-nitroderivatives 3b and 3d. Sulfochlorides 3a– d were independently synthesized from 3,4′-diquinolinyl sulfides 4 and converted to the respective 4-dimethylamino-3-quinoline-N,N-dimethylsulfonamides 9a–d. 相似文献
116.
Danuta Potoczna-Petru Leszek K?piński Ludwina Krajczyk 《Reaction Kinetics and Catalysis Letters》2009,97(2):321-327
The interaction of 1 and 4 nm thick Co films with SiO2 support in vacuum at high temperature has been investigated by TEM, SAED and HRTEM methods. It was found that annealing in
vacuum at 800 °C caused the transformation of the smallest Co particles into Co2Si silicide. 相似文献
117.
Handong Li Leszek Czuchajowski William R. Trumble 《Journal of heterocyclic chemistry》1997,34(3):999-1003
A new type of porphyrinyl-nucleoside was synthesized by the Heck reaction of meso-tri(4-pyndyl)-p-acrylamidophenylporphyrin with (+)5-iodo-2′-deoxyuridine. The porphyrin used in this reaction was also applied in obtaining a water soluble porphyrin polymer and a copolymer with acrylamide. The porphyrinyl-nucleoside and the polymer and copolymer were investigated for their interaction with ds DNA, oligonucleotides and oligonucleotide duplexes. The extend of the red-shift of the Soret band of porphyrins and the slowing of the mobolity of DNA during electrophoresis of the interacting systems suggested that intercalation of cationic porphyrin units into ds DNA cannot be solely responsible for the observed phenomena. 相似文献
118.
119.
Leszek Zalewski Dr. Michael Wykes Sergio Brovelli Dr. Massimo Bonini Dr. Thomas Breiner Dr. Marcel Kastler Dr. Florian Dötz Dr. David Beljonne Dr. Harry L. Anderson Prof. Franco Cacialli Prof. Paolo Samorì Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(13):3933-3941
A dithiophene rotaxane 1 ?β‐CD and its shape‐persistent corresponding dumbbell 1 were synthesized and fully characterized. 2D NOESY experiments, supported by molecular dynamics calculations, revealed a very mobile macrocycle (β‐CD). Steady‐state and time‐resolved photoluminescence experiments in solution were employed to elucidate the excited‐state dynamics for both systems and to explore the effect of cyclodextrin encapsulation. The photoluminescence (PL) spectrum of 1 ?β‐CD was found to be blueshifted with respect to the dumbbell 1 (2.81 and 2.78 eV, respectively). Additionally, in contrast to previous observations, neither PL spectra nor the decay kinetics of both threaded and unthreaded systems showed changes upon increasing the concentration or changing the polarity of the solutions, thereby providing evidence for a lack of tendency toward aggregation of the unthreaded backbone. 相似文献
120.
Hoffmann M Eitner K von Grotthuss M Rychlewski L Banachowicz E Grabarkiewicz T Szkoda T Kolinski A 《Journal of computer-aided molecular design》2006,20(5):305-319
The modeling of the severe acute respiratory syndrome coronavirus helicase ATPase catalytic domain was performed using the protein structure prediction Meta Server and the 3D Jury method for model selection, which resulted in the identification of 1JPR, 1UAA and 1W36 PDB structures as suitable templates for creating a full atom 3D model. This model was further utilized to design small molecules that are expected to block an ATPase catalytic pocket thus inhibit the enzymatic activity. Binding sites for various functional groups were identified in a series of molecular dynamics calculation. Their positions in the catalytic pocket were used as constraints in the Cambridge structural database search for molecules having the pharmacophores that interacted most strongly with the enzyme in a desired position. The subsequent MD simulations followed by calculations of binding energies of the designed molecules were compared to ATP identifying the most successful candidates, for likely inhibitors—molecules possessing two phosphonic acid moieties at distal ends of the molecule. 相似文献