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131.
Elena V. Popova Vladimir F. Mironov Yuliya M. Volodina Nail M. Azancheev Eleonora A. Ishmaeva Igor I. Patsanovsky 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1)
Abstract Tris(trimethy1silyl)phosphine (1) is the key reagent in the synthesis of one- and two-coordinated phosphorus compounds. Its characteristic features are extreme reactivity, high nucleophility of phosphorus atom and the P-Si bonds lability. The interaction of phosphine (1) with bis(catecho1)chlorophosphome (2) has been studied by dynamic 31P NMR method. On the reagents ratio 1:1 at first the nucleophilic substitution of chlorine occurs leading to formation of phosphome (3) with PIII-Pv bond (σP(III) -117.0, σP(V) 17.4 ppm, 1Jpp 305.0 Hz) which converts then into more stable 2-(trimethylsiloxyphenyloxy)-4,5-bem- 1,3,2-dioxaphospholane (4). 相似文献
132.
K. Michal Pietrusiewicz Igor I Patsanovsky Vladimir E. Kataev Eleonora A. Ishmaeva Aleksei V. Kataev W. Wieczorek 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1)
Abstract The molecular structure, polarity and conformations in solution of 1,3,5-tris(diphenylphosphinoxidemethy1ene)benzene 1,3,5-[Ph2P(0)CH2]3C6H3 have been studied by X-ray, dipole moments and quantum chemistry methods. It have been shown, that in crystal molecule has the conformation in which two diphenylphosphinoxide fragments dispose on one and the same side, but the third - on the other side of central benzene ring plane with torsion angles CSP2-CSP2-CSP3-P 60–80° and CSP2-CSP3-P=O about 50–70°. In solution conformational picture is more rich: side by side with the structures realized in crystal, conformations with all three diphenylphosphinoxide fragments disposed on one and the same side of central benzene ring plane with torsion angles CSP2-CSP2-CSP3-P 70-90° and CSP2-CSP3-P=O about 70–75° become preferable. 相似文献
133.
Eleonora Marian Bogdan Tiţa Tunde Jurca Adriana Fuliaş Laura Vicaş Dumitru Tiţa 《Journal of Thermal Analysis and Calorimetry》2013,111(2):1025-1031
The application of thermal methods is of great importance in the solution of pharmaceutical problems, such as the control of raw materials, the determination of purity, the qualitative and quantitative analysis of drug formulation, tests of thermal stability and compatibility, the determination of kinetic parameters etc. The evaluation of thermal stability in the solid state is mostly made by analyzing their decomposition under isothermal and non-isothermal conditions. This study reports the study on the thermal behaviour of erythromycin-active substance and tablets, respectively, the determination of the kinetic parameters for the decomposition process under non-isothermal conditions. For the determination of kinetic parameters from the TG/DTG curves, were utilized the following methods: Friedman isoconversional, Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Li–Tang, and Kissinger, respectively, a dynamic nitrogen atmosphere and different heating rates: 2.5, 5, 7.5, 10, and 15 °C min?1. Thermoanalytical curves showed that the active substance is thermally more stable than the tablets and the values of activation energy indicate a considerable thermal stability of active substance. The decrease in stability was attributed to the presence of excipients. 相似文献
134.
I. I. Patsanovsky E. A. Ishmaeva J. Z. Stepanova V. D. Romanenko L. N. Markovsky 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract Chemistry of twocoordinated phosphorus compounds has been rapidly developed in last years. Parallel with synthesis of new such compounds and investigating of their chemistry research of their spatial and electron structure assumes ever greater importanse. Electrical methods are very informative in this aspect and also permit to determine unknown polaritirs of PII-bonds, that have great self-dependent interest. We have been studed for the first time the acyclic PII-compounds containing P=N, P=C, P=P, P=As, P=Sb - double bonds. Phosphaazenes RIP=NR2, where RI: (Me3Si)2N, 2,4,6-tBu3C6H2; R2: Me3Si, tBu, 2,4,6-tBu3C6H2 have small polarity 1.5–2.0 D, wich describes by one set of parameteres. The main role in stabilization of -P=N-fragment having E-configuration belongs to sterical factors. 相似文献
135.
Fabio Gosetti Eleonora Mazzucco Maria Carla Gennaro Emilio Marengo 《Analytical and bioanalytical chemistry》2013,405(2-3):907-916
The broad group of biogenic amines includes polyamines and catecholamines, whose presence in human tissues and biological fluids can give important diagnostic information and act as marker of many pathologies. In particular, polyamines are involved in cancer cell growth while catecholamines act as neurotransmitters and hormones. Their simultaneous determination in biological tissues and fluids is therefore an important task. A high-performance liquid chromatography tandem mass spectrometry method is presented here for the simultaneous determination in urine of 16 biogenic amines: adrenaline (epinephrine), agmatine, cadaverine, dopamine, histamine, 3-methoxytyramine, noradrenaline (norepinephrine), norephedrine, octopamine, 2-phenylethylamine, putrescine, serotonin, spermidine, spermine, tryptamine, and tyramine. The method does not require any derivatization step. To guarantee the maximum of sensitivity, the mass spectrometer works in selected reaction monitoring mode, monitoring for each analyte the two most intensive transitions. Method validation includes the evaluation of limits of detection (that range from 0.3 to 6.6 μg L?1), limits of quantitation (that range from 1.0 to 21.9 μg L?1), linearity range (three orders of magnitude), recovery, intra- and inter-day precision on both concentration, and retention time. Recovery (R) is shown not to depend on the analyte concentration: the average R percent ranges from 72.9 to 100.0 %. Particular attention is devoted to the matrix effect and the correlated phenomena of ion enhancement or suppression in mass spectrometry detection. Figure
HPLC-MS/MS determination of 16 biogenic amines 相似文献
136.
Catia Contado Eleonora Vighi Alessandro Dalpiaz Eliana Leo 《Analytical and bioanalytical chemistry》2013,405(2-3):703-711
Poly(lactic-co-glycolic acid) particles in the 200–400-nm size range were formulated through nanoprecipitation and solvent evaporation methods. Different concentrations of the polymer and stabilizer (Pluronic® F 68) were tested in order to identify the best conditions for making poly(lactic-co-glycolic acid) particles of suitable size, stable in time, and to be used as carriers for brain-targeting drugs. The particles with the best characteristics for delivery system design were those formulated by nanoprecipitation with an organic/water phase ratio of 2:30, a polymer concentration of 25 mg/mL, and a surfactant concentration of 0.83 mg/mL; their surface charge was reasonably negative (approximately -27 mV) and the average size of the almost monodisperse population was roughly 250 nm. Particle characterization was obtained through ζ-potential measurements, scanning electron microscope observations, and particle size distribution determinations; the latter achieved by both photon-correlation spectroscopy and sedimentation field flow fractionation. Sedimentation field flow fractionation, which is considered more reliable than photon-correlation spectroscopy in describing the possible particle size distribution modifications, was used to investigate the effects of 3 months of storage at 4 °C had on the lyophilized particles. Figure
Particle size ditribution from the SdFFF and the PCS techniques 相似文献
137.
Yassine Oulad El Majdoub Filippo Alibrando Francesco Cacciola Katia Arena Eleonora Pagnotta Roberto Matteo Giuseppe Micalizzi Laura Dugo Paola Dugo Luigi Mondello 《Molecules (Basel, Switzerland)》2020,25(22)
Indian mustard or Brassica juncea (B. juncea) is an oilseed plant used in many types of food (as mustard or IV range salad). It also has non-food uses (e.g., as green manure), and is a good model for phytoremediation of metals and pesticides. In recent years, it gained special attention due to its biological compounds and potential beneficial effects on human health. In this study, different tissues, namely leaves, stems, roots, and flowers of three accessions of B. juncea: ISCI 99 (Sample A), ISCI Top (Sample B), and “Broad-leaf” (Sample C) were analyzed by HPLC-PDA/ESI-MS/MS. Most polyphenols identified were bound to sugars and phenolic acids. Among the three cultivars, Sample A flowers turned were the richest ones, and the most abundant bioactive identified was represented by Isorhamnetin 3,7-diglucoside (683.62 µg/100 mg dry weight (DW) in Sample A, 433.65 µg/100 mg DW in Sample B, and 644.43 µg/100 mg DW in Sample C). In addition, the most complex samples, viz. leaves were analyzed by GC-FID/MS. The major volatile constituents of B. juncea L. leaves extract in the three cultivars were benzenepropanenitrile (34.94% in Sample B, 8.16% in Sample A, 6.24% in Sample C), followed by benzofuranone (8.54% in Sample A, 6.32% in Sample C, 3.64% in Sample B), and phytone (3.77% in Sample B, 2.85% in Sample A, 1.01% in Sample C). The overall evaluation of different tissues from three B. juncea accessions, through chemical analysis of the volatile and non-volatile compounds, can be advantageously taken into consideration for future use as dietary supplements and nutraceuticals in food matrices. 相似文献
138.
Jielin Zhang Eleonora Grandi Haigen Fu Thangavelu Saravanan Laura Bothof Pieter G. Tepper Andy‐Mark W. H. Thunnissen Gerrit J. Poelarends 《Angewandte Chemie (International ed. in English)》2020,59(1):429-435
Aspartic acid derivatives with branched N‐alkyl or N‐arylalkyl substituents are valuable precursors to artificial dipeptide sweeteners such as neotame and advantame. The development of a biocatalyst to synthesize these compounds in a single asymmetric step is an as yet unmet challenge. Reported here is an enantioselective biocatalytic synthesis of various difficult N‐substituted aspartic acids, including N‐(3,3‐dimethylbutyl)‐l ‐aspartic acid and N‐[3‐(3‐hydroxy‐4‐methoxyphenyl)propyl]‐l ‐aspartic acid, precursors to neotame and advantame, respectively, using an engineered variant of ethylenediamine‐N,N′‐disuccinic acid (EDDS) lyase from Chelativorans sp. BNC1. This engineered C–N lyase (mutant D290M/Y320M) displayed a remarkable 1140‐fold increase in activity for the selective hydroamination of fumarate compared to that of the wild‐type enzyme. These results present new opportunities to develop practical multienzymatic processes for the more sustainable and step‐economic synthesis of an important class of food additives. 相似文献
139.
Tommaso Angelini Eleonora Ballerini Simona Bonollo Massimo Curini 《Green Chemistry Letters and Reviews》2014,7(1):11-17
A new protocol for the Henry addition of nitroalkanes to aryl- and alkyl-aldehydes promoted by PS-BEMP under solvent-free conditions (SolFC) is presented. The corresponding nitroaldol products were obtained in good yields and short times; furthermore minimization of the reaction waste was achieved by reducing the use of organic solvents. Extension of the protocol was obtained by setting up the tandem Michael-Henry reaction of α,β-unsaturated aldehydes and nitroalkane to yield the corresponding dinitro derivatives. 相似文献
140.
Mariana Dennehy Ricardo M. Ferullo Eleonora Freire Ricardo Baggio 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(6):627-631
In the title compound, bis(μ‐1,1‐dioxo‐1,2‐benzothiazole‐3‐thiolato)‐κ3N,S:S;κ3S:N,S‐bis[(1,1‐dioxo‐1,2‐benzothiazole‐3‐thiolato‐κ2N,S)(ethanol‐κO)bismuth(III)] ethanol hemisolvate, [Bi2(C7H4NO2S2)6(C2H5OH)2]·0.5C2H5OH, three independent thiosaccharinate (tsac) anions chelate the metal centre through the endocyclic N and exocyclic S atoms. The complex also presnts two `semicoordination' contacts, one from a pendant ethanol solvent molecule and a second one from an S atom of a centrosymmetrically related molecule. This latter interaction complements two π–π interactions between tsac rings to form a dimeric entity which is the elemental unit that builds up the crystal structure. These dinuclear units are connected to each other via a second type of π–π interaction, generating chains along [11]. Two ethanol molecules, one of them of full occupancy at a general position and semicoordinated to the central cation, and a second one depleted and disordered around a symmetry centre, stabilize the structure. The complex was studied theoretically and the vibrational assignations were confirmed by employing theoretical density functional theory (DFT) methods. 相似文献