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401.
Renata Paprocka Leszek Pazderski Liliana Mazur Magorzata Wiese-Szadkowska Jolanta Kutkowska Michalina Nowak Anna Helmin-Basa 《Molecules (Basel, Switzerland)》2022,27(9)
1H-pyrrole-2,5-dione derivatives are known for their wide range of pharmacological properties, including anti-inflammatory and antimicrobial activities. This study aimed to synthesize new 3,4-dimethyl-1H-pyrrole-2,5-dione derivatives 2a–2f in the reaction of N3-substituted amidrazones with 2,3-dimethylmaleic anhydride and evaluate their structural and biological properties. Compounds 2a–2f were studied by the 1H-13C NMR two-dimensional techniques (HMQC, HMBC) and single-crystal X-ray diffraction (derivatives 2a and 2d). The anti-inflammatory activity of compounds 2a–2f was examined by both an anti-proliferative study and a production study on the inhibition of pro-inflammatory cytokines (IL-6 and TNF-α) in anti-CD3 antibody- or lipopolysaccharide-stimulated human peripheral blood mononuclear cell (PBMC) cultures. The antibacterial activity of compounds 2a–2f against Staphylococcus aureus, Enterococcus faecalis, Micrococcus luteus, Esherichia coli, Pseudomonas aeruginosa, Yersinia enterocolitica, Mycobacterium smegmatis and Nocardia corralina strains was determined using the broth microdilution method. Structural studies of 2a–2f revealed the presence of distinct Z and E stereoisomers in the solid state and the solution. All compounds significantly inhibited the proliferation of PBMCs in anti-CD3-stimulated cultures. The strongest effect was observed for derivatives 2a–2d. The strongest inhibition of pro-inflammatory cytokine production was observed for the most promising anti-inflammatory compound 2a. 相似文献
402.
Summary. This analysis of convergence of a coupled FEM-IEM is based on our previous work on the FEM and the IEM for exterior Helmholtz
problems. The key idea is to represent both the exact and the numerical solution by the Dirichlet-to-Neumann operators that
they induce on the coupling hypersurface in the exterior of an obstacle. The investigation of convergence can then be related
to a spectral analysis of these DtN operators. We give a general outline of our method and then proceed to a detailed investigation
of the case that the coupling surface is a sphere. Our main goal is to explore the convergence mechanism. In this context,
we show well-posedness of both the continuous and the discrete models. We further show that the discrete inf-sup constants
have a positive lower bound that does not depend on the number of DOF of the IEM. The proofs are based on lemmas on the spectra
of the continuous and the discrete DtN operators, where the spectral characterization of the discrete DtN operator is given
as a conjecture from numerical experiments. In our convergence analysis, we show algebraic (in terms of N) convergence of arbitrary order and generalize this result to exponential convergence.
Received April 10, 1999 / Revised version received November 10, 1999 / Published online October 16, 2000 相似文献
403.
William R. Trumble Vinay Wandrekar Leszek Czuchajowski 《Journal of heterocyclic chemistry》1996,33(6):1775-1783
meso-Tri(N-memyl-4-pyridinium)porphyrinyl-p-phenylene-5′-O-thymidine, interacting with plasmid ds DNA showed an 8 nm red-shift of the Soret band. The observed Soret band shift was 4 run less than the shift of the respective meso-tetra(N-methyl-4-pyridinium)porphyrin, which is usually assumed to indicate intercalation. Experimental spectra and the MMX- and AM-1 calculations of a series of model structures further suggest that the investigated porphyrinyl-thymidine also interacts with adenine due to its nucleobase. The possibility of intercalation was also viewed based on interaction of immobilized porphyrin with ds DNA. Theoretical considerations suggested that there are no steric limitations to the formation of a system in which the porphyrinyl-thymidine in question interacts with a molecule of porphyrinyl-adenosine, via A-T base pairing, to join two ds DNA molecules. 相似文献
404.
This paper is devoted to an orthotropic cylindricall simply supported shell subjected to external pressure. This analysis is focused on determining geometrical shape of shell. Main subject of investigation is to maximize the stability of the shell. Mathematical model of double layer shell was implemented. Numerical solution was obtained for particular class of shells by using the finite element code ABAQUS. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
405.
Elbieta Jankowska Mirosaw Gilski Mariusz Jasklski Zbigniew Grzonka Leszek ankiewicz 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(6):o353-o354
The crystal structure of the title compound, alternatively called 3‐[4‐(benzyloxy)phenyl]‐2‐(N‐tert‐butoxycarbonyl‐N‐methylamino)propionic acid, C22H27NO5, has been studied in order to examine the role of N‐methylation as a determinant of peptide conformation. The conformation of the tert‐butoxycarbonyl group is trans–trans. The side chain has a folded conformation and the two phenyl rings are effectively perpendicular to one another. The carboxylate hydroxyl group and the urethane carbonyl group form a strong intermolecular O—H?O hydrogen bond. 相似文献
406.
407.
Teobald Kupka Łukasz Gajda Leszek Stobiński Łukasz Kołodziej Adrianna Mnich Aneta Buczek Małgorzata A. Broda 《Magnetic resonance in chemistry : MRC》2019,57(7):359-372
We report on nucleus-independent magnetic shielding (NICS) scans over the centers of six- and five-membered rings in selected metal phthalocyanines (MPc) and fullerene C60 for more accurate characterization of local aromaticity in these compounds. Detailed tests were conducted on model aromatic molecules including benzene, pyrrole, indole, isoindole, and carbazole and subsequently applied to H2Pc, ZnPc, Al(OH)Pc, and CuPc. Similar behavior of three selected magnetic probes, Bq, 3He, and 7Li+, approaching perpendicularly the ring centers, was observed. For better visualization of shielding zone over the centers of aromatic rings, we introduced a simple mathematical procedure: the first and second derivatives of scan curves with respect to magnetic probe position enabled their additional examination. It allowed an easier localization of curve minimum and discrimination between areas in space varying by the magnetic field magnitude and to illustrate local aromaticity of two different kinds of rings in MPc with better resolution. Our results supported earlier reports on very low aromaticity indexes of pyrrole ring incorporated into MPc and significant aromaticity of the central macrocycle. No direct dependence between harmonic oscillator model of aromaticity and NICS was observed. Instead, a correlation between position of scan curve minimum and its magnitude were observed. In addition, the NICS values and 3He chemical shifts in the middle of neutral C60 and C606− anion agreed well with the reported experimental NMR values for He@C60 and He@C606−. 相似文献
408.
409.
Leszek Pazderski Tomasz Pawlak Jerzy Sitkowski Lech Kozerski Edward Szłyk 《Magnetic resonance in chemistry : MRC》2010,48(6):417-426
1H, 13C and 15N NMR studies of gold(III), palladium(II) and platinum(II) chloride complexes with dimethylpyridines (lutidines: 2,3‐lutidine, 2,3lut; 2,4‐lutidine, 2,4lut; 3,5‐lutidine, 3,5lut; 2,6‐lutidine, 2,6lut) and 2,4,6‐trimethylpyridine (2,4,6‐collidine, 2,4,6col) having general formulae [AuLCl3], trans‐[PdL2Cl2] and trans‐/cis‐[PtL2Cl2] were performed and the respective chemical shifts (δ1H, δ13C, δ15N) reported. The deshielding of protons and carbons, as well as the shielding of nitrogens was observed. The 1H, 13C and 15N NMR coordination shifts (Δ1Hcoord, Δ13Ccoord, Δ15Ncoord; Δcoord = δcomplex ? δligand) were discussed in relation to some structural features of the title complexes, such as the type of the central atom [Au(III), Pd(II), Pt(II)], geometry (trans‐ or cis‐), metal‐nitrogen bond lengths and the position of both methyl groups in the pyridine ring system. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
410.
Several compounds may exist in LnCl3–MCl mixtures. Those corresponding to the M 2 LnCl5 and MLn 2Cl7 stoichiometries are formed in a few systems only, with diverse stability strongly dependent on both the corresponding lanthanide and alkali metal. On the other hand, M 3 LnCl6 that occur in most systems have a far larger stability range and melt congruently. These latter compounds were investigated in the present work by differential scanning calorimetry and electrical conductivity measurements. The thermodynamic and transport properties were correlated to structural features and related to the mechanism of compound formation. 相似文献