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61.
Valeria N. Movchun Alexander A. Kolomeitsev Yurii L. Yagupolskii 《Journal of fluorine chemistry》1995,70(2):255-257
Aryltrifluoromethyl-sulfides, -sulfoxides and -sulfones can be prepared by trifluoromethylation of the corresponding arylsulfenyl, -sulfinyl and -sulfonyl halides using (trifluoromethyl)trimethylsilane in the presence of fluoride sources, such as TASF [tris(dimethylamino)sulfonium difluorotrimethylsilicate]. 相似文献
62.
Cali F Ragalmuto A Chiavetta V Calabrese G Fichera M Vinci M Ruggeri G Schinocca P Sturnio M Romano S Romano V Elia M 《Experimental & molecular medicine》2010,42(12):842-848
Angelman syndrome (AS) is a severe neurobehavioural disorder caused by failure of expression of the maternal copy of the imprinted domain located on 15q11-q13. There are different mechanisms leading to AS: maternal microdeletion, uniparental disomy, defects in a putative imprinting centre, mutations of the E3 ubiquitin protein ligase (UBE3A) gene. However, some of suspected cases of AS are still scored negative to all the latter mutations. Recently, it has been shown that a proportion of negative cases bear large deletions overlapping one or more exons of the UBE3A gene. These deletions are difficult to detect by conventional gene-scanning methods due to the masking effect by the non-deleted allele. In this study, we have used for the first time multiplex ligation-dependent probe amplification (MLPA) and comparative multiplex dosage analysis (CMDA) to search for large deletions affecting the UBE3A gene. Using this approach, we identified a novel causative deletion involving exon 8 in an affected sibling. Based on our results, we propose the use of MLPA as a fast, accurate and inexpensive test to detect large deletions in the UBE3A gene in a small but significant percentage of AS patients. 相似文献
63.
Sala F Bagnati R Livi V Cereda R D'Incalci M Zucchetti M 《Journal of mass spectrometry : JMS》2011,46(10):1039-1045
E-3810, 6-[[7-[(1-aminocyclopropyl)methoxy]-6-methoxy-4-quinolyl]oxy]-N-methyl-naphthalene-1-carboxamide, is a novel, potent, dual inhibitor of vascular endothelial growth factor and fibroblast growth factor receptors with antiangiogenic properties, now under early clinical evaluation as an anticancer agent. To investigate its clinical pharmacokinetics, a high-performance liquid chromatography-tandem mass spectrometry method was developed and validated to measure the drug in human plasma on the basis of simple protein precipitation with methanol after addition of deuterated E-3810 as internal standard. The method requires a small volume of sample (100 μl) and is rapid and selective, allowing good resolution of peaks in 5 min. It is sensitive, precise, and accurate, with overall precision, expressed as CV%, always ≤7.1%, accuracy in the range 92.7%-104.4%, and high recovery, close to 100%. The limit of detection is 0.01 ng/ml, and the lower limit of quantitation is 2.0 ng/ml. The assay was validated in the range from the lower limit of quantitation up to 500.0 ng/ml. This is the first method developed and validated for analyzing E-3810 in human plasma. The method has been successfully applied to study E-3810 pharmacokinetics in cancer patients with solid tumors who are receiving daily oral doses of the drug during the phase I trial. 相似文献
64.
Giovanni Di Fabio Valeria RomanucciMauro De Nisco Silvana PedatellaCinzia Di Marino Armando Zarrelli 《Tetrahedron letters》2013
A new and preparative oxidation of silibinin has been developed to give access to two different silibinin derivatives known for their enhanced antioxidant properties. Conventional heating methods were compared with results obtained from microwave (MW) heating. The base-catalysed oxidation of silibinin under MW heating is a very efficient method for the preparation of 2,3-dehydrosilybin and a related silybin rearrangement product. This latter compound shows enhanced radical scavenging properties. Optimised conditions were used to prepare 2,3-dehydrosilybins A and B from optically pure silybins A and B. An efficient, preparative purification method was also developed to enable isolation of different products in high purity. 相似文献
65.
Second-order rate constants, k(OH)(N), M(-)(1) s(-)(1), for the beta-elimination reactions of HF with 2-(2-fluoroethyl)pyridine (2), 3-(2-fluoroethyl)pyridine (3), and 4-(2-fluoroethyl)pyridine (4) in OH(-)/H(2)O, at 50 degrees C and mu = 1 M KCl, are = 0.646 x 10(-)(4) M(-)(1) s(-)(1), = 2.97 x 10(-)(6) M(-)(1) s(-)(1), and = 5.28 x 10(-)(4) M(-)(1) s(-)(1), respectively. When compared with the second-order rate constants for the same processes with the nitrogen-methylated substrates 1-methyl-2-(2-fluoroethyl)pyridinium iodide (5), 1-methyl-3-(2-fluoroethyl)pyridinium iodide (6), and 1-methyl-4-(2-fluoroethyl)pyridinium iodide (7), the methyl-activating factor (MethylAF) can be calculated from the ratio k(OH)(NCH)3/, and a value of 8.7 x 10(5) is obtained with substrates 5/2, a value of 1.6 x 10(3) with 6/3, and a value of 2.1 x 10(4) with 7/4. The high values of MethylAF are in agreement with an irreversible E1cb mechanism (A(N)D(E) + D(N)) for substrates 5 and 7 and with the high stability of the intermediate carbanion related to its enamine-type structure. In acetohydroxamate/acetohydroxamic acid buffers (pH 8.45-9.42) and acetate/acetic acid buffers (pH 4.13-5.13), the beta-elimination reactions of HF, with substrates 2 and 4, occur at NH(+), the substrates protonated at the nitrogen atom of the pyridine ring, even when the [NH(+)] is much lower than the [N], the unprotonated substrate, due to the high proton-activating factor (PAF) value observed: 3.6 x 10(5) for 2 and 6.5 x 10(4) for 4 with acetohydroxamate base. These high PAF values are indicative of an irreversible E1cb mechanism rather than a concerted E2 (A(N)D(E)D(N)) mechanism. Finally, the rate constant for carbanion formation from NH(+) with 2 is k(B)(NH)+ = 0.35 M(-)(1) s(-)(1), which is lower than when chlorine is the leaving group ( = 1.05 M(-)(1) s(-)(1); Alunni, S.; Busti, A. J. Chem. Soc., Perkin Trans. 2 2001, 778). This is direct experimental evidence that some lengthening of the carbon-leaving group bond can occur in the intermediate carbanion. This is a point of interest for interpreting a heavy-atom isotope effect. 相似文献
66.
Valeria Di Bussolo 《Tetrahedron》2010,66(3):689-697
The addition of primary and secondary aliphatic amines to glycal-derived allyl epoxides is completely 1,2-regio- and anti-stereoselective, whereas mixtures of the corresponding anti-1,2- [3-N-(substituted-amino) glycals] and anti-1,4-addition products (N-glycosyl amines) are obtained with N-(mesyl)-aziridines. In this way, structural moieties, otherwise difficult to synthesize, are obtained by means of a very simple protocol. The regio- and stereoselectivity observed with epoxides is the consequence of an isomerization process, whereas the result obtained with aziridines is explained by the absence of an effective substrate-nucleophile (amine) coordination. 相似文献
67.
Development and validation of a capillary electrophoresis method for determination of enantiomeric purity and related substances of esomeprazole in raw material and pellets 下载免费PDF全文
Pablo Estevez Sabrina Flor Oriana Boscolo Valeria Tripodi Silvia Lucangioli 《Electrophoresis》2014,35(6):804-810
A capillary electrophoresis method using CDs for quality control of esomeprazole (ESO) in terms of enantiomeric purity and related substances in raw material and pellets was developed. ESO is the S‐enantiomer of omeprazole (OMZ). Several parameters were evaluated, including type and concentration of buffer and CD, concentration of additives and electrolyte pH. Resolution between the enantiomers of OMZ obtained for each parameter tested was calculated and the presence of the main related substance such as OMZ sulfone was carefully monitored. The optimized system consisted of 100 mM Tris‐phosphate buffer pH 2.5 with 20 mM 2‐hydroxypropyl‐β‐CD, 1 mM sodium dithionite, temperature at 15°C, voltage at 28 kV, and UV detection at 301 nm. Once optimized, the electrophoretic system was validated according to ICH guidelines. The limits of detection and quantification for R‐OMZ were 0.6 μg/mL (0.06% w/w of ESO) and 2.0 μg/mL (0.2% w/w of ESO), respectively. A mean concentration of R‐OMZ <0.2% limit established by the United States Pharmacopeia (USP) was found in the raw material and six‐pellet samples of ESO. No other impurities were found in the samples under these conditions. Therefore, the developed method was found to be appropriate not only for enantiomeric quality control of ESO but also for the analysis of ESO and the main related substance in raw material and pharmaceutical formulations as well as for stability indicating studies. 相似文献
68.
Valeria Angeli Simona Biagi Silvia Ghimenti Massimo Onor Alessandro D'Ulivo Emilia Bramanti 《Spectrochimica Acta Part B: Atomic Spectroscopy》2011,66(11-12):799-804
Monomethylmercury and ethylmercury were determined on line using flow injection-chemical vapor generation atomic fluorescence spectrometry without neither requiring a pre-treatment with chemical oxidants, nor UV/MW additional post column interface, nor organic solvents, nor complexing agents, such as cysteine. Inorganic mercury, monomethylmercury and ethylmercury were detected by atomic fluorescence spectrometry in an Ar/H2 miniaturized flame after sodium borohydride reduction to Hg0, monomethylmercury hydride and ethylmercury hydride, respectively. The effect of mercury complexing agent such as cysteine, ethylendiaminotetracetic acid and HCl with respect to water and Ar/H2 microflame was investigated.The behavior of inorganic mercury, monomethylmercury and ethylmercury and their cysteine-complexes was also studied by continuous flow-chemical vapor generation atomic fluorescence spectrometry in order to characterize the reduction reaction with tetrahydroborate. When complexed with cysteine, inorganic mercury, monomethylmercury and ethylmercury cannot be separately quantified varying tetrahydroborate concentration due to a lack of selectivity, and their speciation requires a pre-separation stage (e.g. a chromatographic separation). If not complexed with cysteine, monomethylmercury and ethylmercury cannot be separated, as well, but their sum can be quantified separately with respect to inorganic mercury choosing a suitable concentration of tetrahydroborate (e.g. 10? 5 mol L? 1), thus allowing the organic/inorganic mercury speciation.The detection limits of the flow injection-chemical vapor generation atomic fluorescence spectrometry method were about 45 nmol L? 1 (as mercury) for all the species considered, a relative standard deviation ranging between 1.8 and 2.9% and a linear dynamic range between 0.1 and 5 μmol L? 1 were obtained. Recoveries of monomethylmercury and ethylmercury with respect to inorganic mercury were never less than 91%. Flow injection-chemical vapor generation atomic fluorescence spectrometry method was validated by analyzing the TORT-1 certificate reference material, which contains only monomethylmercury, and obtaining 83 ± 5% of monomethylmercury recovered, respectively. This method was also applied to the determination of monomethylmercury in saliva samples. 相似文献
69.
Siraye E. Debebe Desta A. Gedefaw Wendimagegn Mammo Teketel Yohannes Francesca Tinti Alberto Zanelli Valeria Fattori Nadia Camaioni 《Journal of polymer science. Part A, Polymer chemistry》2011,49(12):2693-2699
The synthesis and characterization of a novel polythiophene substituted with a 2′‐pentyloxy‐5′‐(1″′‐oxooctyl) phenyl group (PPOPT) is reported. The bulk transport properties of thin films of PPOPT are investigated by admittance spectroscopy. The dramatic effect of the phenyl side chain on the mobility of positive carriers in films of PPOPT is described. The photophysics of PPOPT in both solution and thin film is also investigated and correlated to substituent‐driven intrachain and interchain arrangements. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
70.
Valerio Annovazzi-Lodi Giuseppe Aromataris Mauro Benedetti Michael Hamacher Sabina Merlo Valeria Vercesi 《Optical and Quantum Electronics》2010,42(3):143-156
In this paper, we numerically evaluate private data transmission using a three-laser scheme, consisting of a pair of twin
semiconductor lasers, driven to chaos by delayed optical feedback in a short cavity, and optically injected by a third chaotic
laser which forces them to synchronize. This laser is selected with different internal parameters with respect to the twin
pair, so that the emissions of the synchronized, matched lasers, are highly correlated, whereas their correlation with the
driver is low. The digital message modulates the emission of the transmitter, as in a standard Chaos Modulation scheme. Message
recovery is then obtained by subtracting, from the transmitted chaos-masked message, the chaos, locally generated by the synchronized
receiver laser. Simulations have been performed with the Lang-Kobayashi model, and, in view of application to private transmission,
we have investigated the effect of the parameter mismatch, between transmitter and receiver, on message recovery. A preliminary
experimental evaluation has been also performed using specially designed InP integrated modules. 相似文献