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51.
Wójcik Kamil Czaja Tomasz Szostak Roman Grzeszczuk Maria 《Journal of Solid State Electrochemistry》2018,22(12):3933-3945
Journal of Solid State Electrochemistry - Silver(I) halide particles embodied in polypyrrole matrices are synthesized and further processed electrochemically to get nanoparticles of silver with... 相似文献
52.
Effect of ligand radicals on vibrational IR, Raman and vibronic spectra of europium beta-diketonates
Tsaryuk V Zolin V Legendziewicz J Szostak R Sokolnicki J 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(1-2):185-191
Vibrational IR, Raman spectra and vibronic sidebands of Eu(3+) electronic transitions of europium tris-beta-diketonates Eu(beta)(3).Ph (beta-dipyvaloylmethane (DPM), acetylacetone (AA), benzoylacetone (BA), thenoyltrifluoroacetone (TTFA) and other beta-diketones; Ph-methyl-, phenyl-, and nitro-derivatives of 1,10-phenanthroline (Phen)) as well as Eu(beta)(3).Bpy and Eu(beta)(3).D-Bpy (Bpy- and D-Bpy-H- and D-2,2'-bipyridine) were studied. Effect of ligand radical properties on spectra and manifestation of the reciprocal influence of non-equivalent ligands in spectra are discussed. Dependence of the spectra on electronic density distribution in both ligands as well as on the strength of M-O and M-N bonds at the variation of radicals of one of the ligands, beta or Ph, was examined. Shape of vibronic sidebands was analysed. Behaviour of bands in the middle and far regions of IR spectra of the series Eu(beta)(3).Phen and Eu(TTFA)(3).Ph was investigated. Increase of the polarising influence of Eu(3+) ions on Phen and Bpy molecules and strengthening the Eu-N bonds in TTFA compounds in comparison with DPM compounds were disclosed from the Raman spectra of Eu(beta)(3).Phen and Eu(beta)(3).Bpy, that is in accordance with properties of beta-diketone radicals. Conclusion about weaker Eu-N bonds in europium beta-diketonates with heterocyclic diimines in comparison with corresponding nitrates was derived from the spectra. Spectral data concerning the relative strength of Eu-ligand bonds are in agreement with available X-ray data. 相似文献
53.
A. Migdał-Mikuli N. Górska E. Szostak 《Journal of Thermal Analysis and Calorimetry》2007,90(1):223-228
Phase transition and thermal decomposition of hexadimethylsulfoxidealuminium chloride were studied by differential scanning
calorimetry (DSC), thermogravimetry (TG) and simultaneous differential thermal analysis (SDTA). The gaseous products of the
decomposition were on-line identified by a quadrupole mass spectrometer (QMS). In the temperature range of 95–300 K, [Al(DMSO)6]Cl3 indicates one phase transition at T
ch=244.96 K (on heating) and at T
cc=220.87 K (on cooling). Large thermal hysteresis of the phase transition (∼24 K) indicates its first order character. Large
value of transition entropy (ΔS≈40 J mol−1 K−1) suggests its configurational character. Thermal decomposition of the title compound proceeds in four main stages. In the
first stage, which starts just above ca. 300 K, the compound loses two DMSO molecules per one formula unit and undergoes into
[Al(DMSO)4]Cl3. In the second stage, the next three DMSO ligands are released and simultaneously decomposed. The third stage, which continues
up to ca. 552 K, is connected with a loss of the last DMSO ligand and the formation of AlCl3. In the fourth stage AlCl3 reacts with carbon monoxide that originates from the decomposition of DMSO, and first aluminium oxychloride and next solid
Al2O3 plus carbon are created. 相似文献
54.
Pengcheng Gao Jihong Xu Tongliang Zhou Dr. Yanhong Liu Prof. Dr. Elwira Bisz Dr. Błażej Dziuk Prof. Dr. Roger Lalancette Prof. Dr. Roman Szostak Prof. Dr. Dongju Zhang Prof. Dr. Michal Szostak 《Angewandte Chemie (International ed. in English)》2023,62(12):e202218427
In the last decade, major advances have been made in homogeneous gold catalysis. However, AuI/AuIII catalytic cycle remains much less explored due to the reluctance of AuI to undergo oxidative addition and the stability of the AuIII intermediate. Herein, we report activation of aryl halides at gold(I) enabled by NHC (NHC=N-heterocyclic carbene) ligands through the development of a new class of L-shaped heterobidentate ImPy (ImPy=imidazo[1,5-a]pyridin-3-ylidene) N,C ligands that feature hemilabile character of the amino group in combination with strong σ-donation of the carbene center in a rigid conformation, imposed by the ligand architecture. Detailed characterization and control studies reveal key ligand features for AuI/AuIII redox cycle, wherein the hemilabile nitrogen is placed at the coordinating position of a rigid framework. Given the tremendous significance of homogeneous gold catalysis, we anticipate that this ligand platform will find widespread application. 相似文献
55.
Anna Migdał-Mikuli Elżbieta Szostak K. Drużbicki Diana Dołȩga 《Journal of Thermal Analysis and Calorimetry》2008,93(3):853-856
Tetrakis(dimethyl sulphoxide)nickel(II) bis(iodide) was studied by thermogravimetry (TG) and simultaneous differential thermal
analysis (SDTA) and differential scanning calorimetry (DSC). The gaseous products of the decomposition were on-line identified
by a quadrupole mass spectrometer (QMS). Thermal decomposition of the title compound proceeds in three main stages. In the
first stage, which starts just above ca. 419 K, the compound loses two dimethyl sulphoxide (DMSO) molecules per one formula
unit and small amount of iodide ion. In the second stage (464–552 K) the next DMSO ligands and the iodide ion simultaneously
are released. In the last stage (552–900 K) NiSO4 is created which next decomposes to NiO and SO3. 相似文献
56.
N-methyl amino acids (N-Me AAs) are a common component of nonribosomal peptides (NRPs), a class of natural products from which many clinically important therapeutics are obtained. N-Me AAs confer peptides with increased conformational rigidity, membrane permeability, and protease resistance. Hence, these analogues are highly desirable building blocks in the ribosomal synthesis of unnatural peptide libraries, from which functional, NRP-like molecules may be identified. By supplementing a reconstituted Escherichia coli translation system with specifically aminoacylated total tRNA that has been chemically methylated, we have identified three N-Me AAs (N-Me Leu, N-Me Thr, and N-Me Val) that are efficiently incorporated into peptides by the ribosome. Moreover, we have demonstrated the synthesis of peptides containing up to three N-Me AAs, a number comparable to that found in many NRP drugs. With improved incorporation efficiency and translational fidelity, it may be possible to synthesize combinatorial libraries of peptides that contain multiple N-Me AAs. Such libraries could be subjected to in vitro selection methods to identify drug-like, high-affinity ligands for protein targets of interest. 相似文献
57.
58.
59.
Roman Szostak 《Journal of Raman spectroscopy : JRS》2011,42(5):1185-1192
Raman spectra of the Cl3CCHO/CCl4 and Cl3CCHO/C6D12 binary systems were recorded as a function of the mole fraction. Features originating from self‐aggregates of chloral (trichloroethanal, trichloroacetaldehyde—TCAA) molecules were detected in different spectral regions. The most pronounced changes were observed in the vicinity of the ν(CO) and ν(C H) stretching vibration bands. Using two‐dimensional correlation spectroscopy (2D‐COS), evolving‐factor analysis (EFA) and multivariate curve resolution (MCR), dimer bands were identified, and their positions were determined. The ν(C H) stretching vibration band in dimers was blue‐shifted by nearly 18 cm−1, whereas the ν(CO) dimer band was red‐shifted by more than 5 cm−1. For these bands, the observed shifts were accompanied by an almost twofold change in the bandwidth, from approximately 19 and 6 cm−1 for dilute solutions (x = 0.05) to 36.6 and 11.5 cm−1, respectively, in pure TCAA. The formation of dimers was confirmed by multivariate analysis of the Raman spectra of chloral recorded as a function of temperature. Analogous analysis of dichloroacetyl chloride (DCAC) spectra gave an 8.9 cm−1 blue shift for the ν(C H) vibration band and − 5.5/− 10.1 cm−1 shifts for the ν(CO) stretching vibrations of the two conformers present. To facilitate the interpretation of experimental findings, the optimized geometries and vibrational wavenumbers of the Cl3CCHO/HCl2CCClO molecules and (Cl3CCHO)2/(HCl2CCClO)2 dimers were calculated at the B3LYP/6‐311 + + G(3df,3pd) level. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
60.
Powner MW Sutherland JD Szostak JW 《Journal of the American Chemical Society》2010,132(46):16677-16688
The recent development of a sequential, high-yielding route to activated pyrimidine nucleotides, under conditions thought to be prebiotic, is an encouraging step toward the greater goal of a plausible prebiotic pathway to RNA and the potential for an RNA world. However, this synthesis has led to a disparity in the methodology available for stepwise construction of the canonical pyrimidine and purine nucleotides. To address this problem, and further explore prebiotically accessible chemical systems, we have developed a high-yielding, aqueous, one-pot, multicomponent reaction that tethers masked-sugar moieties to prebiotically plausible purine precursors. A pH-dependent three-component reaction system has been discovered that utilizes key nucleotide synthons 2-aminooxazole and 5-aminoimidazoles, which allows the first divergent purine/pyrimidine synthesis to be proposed. Due to regiospecific aminoimidazole tethering, the pathway allows N9 purination only, thus suggesting the first prebiotically plausible mechanism for regiospecific N9 purination. 相似文献