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991.
Flores G Díaz-Plaza EM Cortés JM Villén J Herraiz M 《Journal of chromatography. A》2008,1211(1-2):99-103
The use of absorbents as retaining materials in the through oven transfer adsorption desorption interface (TOTAD) of an on-line coupled reversed-phase liquid chromatography-gas chromatography system (RPLC-GC) is proposed for the first time. A comparative study of an adsorbent (Tenax TA) and two absorbents, namely polydimethylsiloxane and poly(50% phenyl/50% methylsiloxane) is performed to establish the best experimental conditions for the automated and simultaneous determination of 15 organophosphorus and organochlorine pesticide residues in olive oil. The proposed method provides satisfactory repeatability (RSDs lower, in general, than 8.5%) and sensitivity (limits of detection ranging from 0.6 to 81.9 microg/L) for the investigated compounds. 相似文献
992.
Monika Wujec Agata Siwek Marta Swatko‐Ossor Liliana Mazur Zofia Rzaczynska 《Journal of heterocyclic chemistry》2008,45(6):1893-1896
993.
994.
Inverse problem for Lagrangian systems on Lie algebroids and applications to reduction by symmetries
María Barbero-Liñán Marta Farré Puiggalí David Martín de Diego 《Monatshefte für Mathematik》2016,180(4):665-691
The language of Lagrangian submanifolds is used to extend a geometric characterization of the inverse problem of the calculus of variations on tangent bundles to regular Lie algebroids. Since not all closed sections are locally exact on Lie algebroids, the Helmholtz conditions on Lie algebroids are necessary but not sufficient, so they give a weaker definition of the inverse problem. As an application the Helmholtz conditions on Atiyah algebroids are obtained so that the relationship between the inverse problem and the reduced inverse problem by symmetries can be described. Some examples and comparison with previous approaches in the literature are provided. 相似文献
995.
Single‐drop microextraction combined in‐line with capillary electrophoresis for the determination of nonsteroidal anti‐inflammatory drugs in urine samples
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Alejandro García‐Vázquez Francesc Borrull Marta Calull Carme Aguilar 《Electrophoresis》2016,37(2):274-281
This study describes a method to determine nonsteroidal anti‐inflammatory drugs (NSAIDs) in urine samples based on the use of single‐drop microextraction (SDME) in a three‐phase design as a preconcentration technique coupled in‐line to capillary electrophoresis. Different parameters affecting the extraction efficiency of the SDME process were evaluated (e.g. type of extractant, volume of the microdroplet, and extraction time). The developed method was successfully applied to the analysis of human urine samples with LODs ranging between 1.0 and 2.5 μg/mL for all of the NSAIDs under study. This method shows RSD values ranging from 8.5 to 15.3% in interday analysis. The enrichment factors were calculated, resulting 27‐fold for ketoprofen, 14‐fold for diclofenac, 12‐fold for ibuprofen, and 44‐fold naproxen. Samples were analyzed applying the SDME–CE method and the obtained results presented satisfactory recovery values (82–115%). The overall method can be considered a promising approach for the analysis of NSAIDs in urine samples after minimal sample pretreatment. 相似文献
996.
The novel derivative of quercetin 3′-O-(3-chloropivaloyl)quercetin (CPQ) inhibited a-glucosidase in a non-competitive manner with an efficacy exceeding that of the parent quercetin. In addition, it inhibited aldose reductase isolated from rat lenses with an IC50 in the low micromolar range and attenuated sorbitol accumulation in isolated rat eye lenses with an activity comparable with that of quercetin. Moreover, it scavenged stable free-radicals of DPPH more efficiently than did quercetin. By inhibiting α-glucosidase and affecting both the polyol pathway and oxidative stress, CPQ represents a promising agent for the multi-targeted pharmacology of diabetic complications. 相似文献
997.
Marek Gołębiowski Aleksandra Ostachowska Monika Paszkiewicz Mieczysława I. Boguś Emilia Włóka Marta Ligęza-Żuber Piotr Stepnowski 《Chemical Papers》2016,70(10):1360-1369
Entomopathogenic fungi are referred to as potential candidates as insect pest control agents. The objective of the study was to identify fatty acids and amino acids from Conidiobolus coronatus cultured on two different media. Each medium was extracted with ethyl acetate and its mixtures with isopropanol, acetonitrile and methanol. Analyses of fatty acids and amino acids of entomopathogenic fungus C. coronatus were performed by means of gas chromatography coupled with mass spectrometry. The analysis showed that the fungus C. coronatus produces the following groups of compounds: fatty acids and amino acids; α- and β-glucopyranose were also identified. The identified fatty acids included 12–20, 22 and 24 carbon atoms per chain. The highest content of fatty acids was detected in a mycelium sample cultured in a liquid minimal medium extracted with ethyl acetate. The lowest content of these organic compounds was identified in mycelium cultured in a liquid nutrient-rich medium extracted with ethyl acetate–methanol mixture. Fatty acids were found to account for 62.0 mass % to 94.4 mass % of all organic compounds in the analyzed mycelia. C18:1 acids were detected in the highest amounts when ethyl acetate was used as the extracting agent. The identified amino acids accounted for 4 mass % to 21 mass % of all organic compounds. Upon extraction of C. coronatus mycelium samples with the ethyl acetate—methanol mixture, two anomeric forms of glucose were also identified. An analysis of the studied material confirmed, that the entomopathogenic fungus C. coronatus is a very rich source of organic compounds, which might encourage its further research so as to identify an even larger number of compounds being produced by this species. 相似文献
998.
Marta Lores Maria LlompartAuthor VitaeGerardo Alvarez-RiveraAuthor Vitae Eugenia GuerraAuthor VitaeMarlene VilaAuthor Vitae Maria CeleiroAuthor VitaeJ. Pablo LamasAuthor Vitae Carmen Garcia-JaresAuthor Vitae 《Analytica chimica acta》2016
Cosmetic products placed on the market and their ingredients, must be safe under reasonable conditions of use, in accordance to the current legislation. Therefore, regulated and allowed chemical substances must meet the regulatory criteria to be used as ingredients in cosmetics and personal care products, and adequate analytical methodology is needed to evaluate the degree of compliance. This article reviews the most recent methods (2005–2015) used for the extraction and the analytical determination of the ingredients included in the positive lists of the European Regulation of Cosmetic Products (EC 1223/2009): comprising colorants, preservatives and UV filters. It summarizes the analytical properties of the most relevant analytical methods along with the possibilities of fulfilment of the current regulatory issues. The cosmetic legislation is frequently being updated; consequently, the analytical methodology must be constantly revised and improved to meet safety requirements. The article highlights the most important advances in analytical methodology for cosmetics control, both in relation to the sample pretreatment and extraction and the different instrumental approaches developed to solve this challenge. 相似文献
999.
Kézia Santana de Moura Hugo Rafael Chaves da Silva Leonardo Prezzi Dornelles Luana Cassandra Breitenbach Barroso Coelho Thiago Henrique Napoleão Maria Danielly Lima de Oliveira Patrícia Maria Guedes Paiva 《Applied biochemistry and biotechnology》2016,180(7):1361-1371
Moringa oleifera seeds contain a water-soluble lectin [water-soluble M. oleifera lectin (WSMoL)] that has shown coagulant activity. Magnesium ions are able to interfere with the ability of this lectin to bind carbohydrates. In this study, we performed structural characterization of WSMoL and analyzed its effect on the electrical resistance of a kaolin clay suspension in both presence and absence of monosaccharides (N-acetylglucosamine, glucose, or fructose) and magnesium ions. The coagulant activity of WSMoL was monitored by measuring optical density and electrical resistance over a period of 60 min. Native WSMoL had a molecular mass of 60 kDa and exhibited anionic nature (pI 5.5). In sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE), it appeared as three polypeptide bands of 30, 20, and 10 kDa. WSMoL reduced the optical density and electrical resistance of the kaolin suspension, which suggests that suspended particles are destabilized and that this is followed by formation of complexes. The coagulant activity of lectin decreased in the presence of Mg2+ ions and carbohydrates at concentrations that also inhibited hemagglutinating activity. This was most likely due to conformational changes in lectin structure. Our findings suggest that the coagulant activity of WSMoL is enhanced by lowering of electrical resistance of the medium and is impaired by lectin–carbohydrate and lectin–Mg2+ interactions. 相似文献
1000.
Near‐IR Emitting Iridium(III) Complexes with Heteroaromatic β‐Diketonate Ancillary Ligands for Efficient Solution‐Processed OLEDs: Structure–Property Correlations
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Dr. Sagar Kesarkar Dr. Wojciech Mróz Dr. Marta Penconi Dr. Mariacecilia Pasini Dr. Silvia Destri Dr. Marco Cazzaniga Dr. Davide Ceresoli Prof. Patrizia R. Mussini Dr. Clara Baldoli Dr. Umberto Giovanella Dr. Alberto Bossi 《Angewandte Chemie (International ed. in English)》2016,55(8):2714-2718
Three NIR‐emitting neutral IrIII complexes [Ir(iqbt)2(dpm)] ( 1 ), [Ir(iqbt)2(tta)] ( 2 ), and [Ir(iqbt)2(dtdk)] ( 3 ) based on the 1‐(benzo[b]thiophen‐2‐yl)‐isoquinolinate (iqtb) were synthesized and characterized (dpm=2,2,6,6‐tetramethyl‐3,5‐heptanedionate; tta=2‐thienoyltrifluoroacetonate; dtdk=1,3‐di(thiophen‐2‐yl)propane‐1,3‐dionate). The compounds emit between λ=680 and 850 nm with high luminescence quantum yields (up to 16 %). By combining electrochemistry, photophysical measurements, and computational modelling, the relationship between the structure, energy levels, and properties were investigated. NIR‐emitting, solution‐processed phosphorescent organic light‐emitting devices (PHOLEDs) were fabricated using the complexes. The devices show remarkable external quantum efficiencies (above 3 % with 1 ) with negligible efficiency roll‐off values, exceeding the highest reported values for solution‐processible NIR emitters. 相似文献