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991.
Study of the Complexation of Pb(II) with meso‐2,3‐ Dimercaptosuccinic Acid (DMSA) and 2,3‐Dimercapto‐1‐propanesulfonic acid (DMPS) Using a Bismuth‐Bulk Rotating Disk Electrode
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María de la Gala Morales Cristina Ariño José Manuel Díaz‐Cruz Miquel Esteban 《Electroanalysis》2014,26(9):1912-1919
For the first time, the suitability of bismuth bulk rotating disk electrode (BiB‐RDE) for the study of metal complexation has been tested. Cyclic (CV) and differential pulse (DPV) voltammetry have been used to study the complexation of Pb(II) with two of the most effective chelating agents for the treatment of Pb(II) poisoning (meso‐2,3‐dimercaptosuccinic acid, DMSA, and 2,3‐dimercapto‐1‐propanesulfonic acid, DMPS). Multivariate curve resolution has been applied to voltammetric data to obtain the stoichiometries and stability constants of the complexes formed. In both systems, the ML2 complex was predominant, with log β2 values of 10.13 and 8.80 for DMSA‐Pb(II) and DMPS‐Pb(II), respectively. 相似文献
992.
Pressure‐sensitive adhesives (PSA) are used to manufacture labels that are applied directly on the food. These adhesives could contain not only intentionally added compounds (IAS) to the adhesive formula but also non‐intentionally added substances (NIAS), due to the impurities from the raw materials used, decomposition of the initial components or from chemical interactions between them. These compounds could migrate to the food and contaminate it. In this study, gas chromatography coupled with mass spectrometry (GC‐MS/Q) and atmospheric pressure gas chromatography coupled to a quadrupole hyphenated to a time of flight mass spectrometer (APGC‐MS/Q‐TOF) have been used for identification of unknown compounds and NIAS coming from a PSA. Seven compounds were identified by GC‐MS/Q, and other eight compounds remained initially unknown. The structure of these eight new compounds was elucidated by working with the spectra obtained by APGC‐MS/Q‐TOF. Finally, two different migration studies were carried out. The first one with Tenax as solid food simulant in contact with the paper label containing the adhesive and the second one with isooctane filled in a natural pork intestine where the label containing the adhesive was applied on the external side. The results are shown and discussed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
993.
Hydride Migration from a Triangular Face to a Tetrahedral Cavity in Tetranuclear Iron Carbonyl Clusters upon Coordination of [AuPPh3]+ Fragments
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Dr. Marco Bortoluzzi Dr. Iacopo Ciabatti Dr. Cristina Femoni Dr. Mohammad Hayatifar Prof. Maria Carmela Iapalucci Prof. Giuliano Longoni Prof. Stefano Zacchini 《Angewandte Chemie (International ed. in English)》2014,53(28):7233-7237
Metal hydrides are of fundamental importance in chemistry, both as solid‐state materials and molecular compounds. The first low‐valent molecular metal cluster containing an interstitial four‐coordinate hydride in a tetrahedral site is decribed, which undergoes hydride migration from the surface to the tetrahedral cavity of the cluster upon coordination of a [AuPPh3]+ fragment. The [HFe4(CO)12(AuPPh3)2]? mono‐anion, which contains a surface μ3‐H, was obtained from the reaction of [HFe4(CO)12]3? with two equivalents of [Au(PPh3)Cl]. This is, in turn, transformed into the neutral [HFe4(CO)12(AuPPh3)3] upon addition of a third [AuPPh3]+ fragment, with concomitant migration of the unique hydride from the surface of the cluster to its tetrahedral cavity. All of these species have been fully characterized in solution by means of IR and multinuclear NMR spectroscopy, and in the solid state by single‐crystal X‐ray diffractometry. 相似文献
994.
Cavitand‐Grafted Silicon Microcantilevers as a Universal Probe for Illicit and Designer Drugs in Water
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Dr. Elisa Biavardi Dr. Stefania Federici Dr. Cristina Tudisco Dr. Daniela Menozzi Dr. Chiara Massera Andrea Sottini Prof. Guglielmo G. Condorelli Dr. Paolo Bergese Prof. Enrico Dalcanale 《Angewandte Chemie (International ed. in English)》2014,53(35):9183-9188
The direct, clean, and unbiased transduction of molecular recognition into a readable and reproducible response is the biggest challenge associated to the use of synthetic receptors in sensing. All possible solutions demand the mastering of molecular recognition at the solid–liquid interface as prerequisite. The socially relevant issue of screening amine‐based illicit and designer drugs is addressed by nanomechanical recognition at the silicon–water interface. The methylamino moieties of different drugs are all first recognized by a single cavitand receptor through a synergistic set of weak interactions. The peculiar recognition ability of the cavitand is then transferred with high fidelity and robustness on silicon microcantilevers and harnessed to realize a nanomechanical device for label‐free detection of these drugs in water. 相似文献
995.
Development of CN Coupling Using Mechanochemistry: Catalytic Coupling of Arylsulfonamides and Carbodiimides
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Davin Tan Cristina Mottillo Athanassios D. Katsenis Dr. Vjekoslav Štrukil Prof. Dr. Tomislav Friščić 《Angewandte Chemie (International ed. in English)》2014,53(35):9321-9324
Reported herein is the mechanochemical synthesis of sulfonyl guanidines, a family of molecules which are relevant as pharmaceuticals and herbicides, by direct coupling of sulfonamides and aromatic or aliphatic carbodiimides. Attempts to conduct the coupling in solution have either failed or given very low conversions, thus demonstrating mechanochemistry as the necessary component for the discovery of this synthetic strategy. 相似文献
996.
Dr. Luminita Marin Dr. Simona Moraru Dr. Maria‐Cristina Popescu Alina Nicolescu Cristina Zgardan Prof. Dr. Bogdan C. Simionescu Dr. Mihail Barboiu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(16):4814-4821
An investigation of the constitutional adaptive gelation process of chitosan/cinnamaldehyde ( C / Cy ) dynagels is reported. These gels generate timely variant macroscopic organization across extended scales. In the first stage, imine‐bond formation takes place “in‐water” and generates low‐ordered hydrogels. The progressive formation of imine bonds further induces “ out‐of‐water” increased reactivity within interdigitated hydrophobic self‐assembled layers of Cy , with a protecting environmental effect against hydrolysis and that leads to the stabilization of the imine bonds. The hydrophobic swelling due to Cy layers at the interfaces reaches a critical step when lamellar self‐organized hybrids are generated (24 hours). This induces an important restructuration of the hydrogels on the micrometric scale, thus resulting in the formation of highly ordered microporous xerogel morphologies of high potential interest for chemical separations, drug delivery, and sensors. 相似文献
997.
Cathepsin‐B Induced Controlled Release from Peptide‐Capped Mesoporous Silica Nanoparticles
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Cristina de la Torre Laura Mondragón Carmen Coll Félix Sancenón María D. Marcos Ramón Martínez‐Máñez Pedro Amorós Mar Orzáez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(47):15309-15314
New capped silica mesoporous nanoparticles for intracellular controlled cargo release within cathepsin B expressing cells are described. Nanometric mesoporous MCM‐41 supports loaded with safranin O ( S1‐P ) or doxorubicin ( S2‐P ) containing a molecular gate based on a cathepsin B target peptidic sequence were synthesized. Solids were designed to show “zero delivery” and to display cargo release in the presence of cathepsin B enzyme, which selectively hydrolyzed in vitro the capping peptide sequence. Controlled delivery in HeLa, MEFs WT, and MEFs lacking cathepsin B cell lines were also tested. Release of safranin O and doxorubicin in these cells took place when cathepsin B was active or present. Cells treated with S2‐P showed a fall in cell viability due to nanoparticles internalization, cathepsin B hydrolysis of the capping peptide, and cytotoxic agent delivery, proving the possible use of these nanodevices as new therapeutic tools for cancer treatment. 相似文献
998.
Microwave‐Assisted Tandem Organocatalytic Peptide‐Coupling Intramolecular aza‐Michael Reaction: α,β‐Unsaturated N‐Acyl Pyrazoles as Michael Acceptors
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Dr. María Sánchez‐Roselló Cristina Mulet Marta Guerola Dr. Carlos del Pozo Prof. Santos Fustero 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(48):15697-15701
Conjugated N‐acyl pyrazoles have been successfully employed in the organocatalytic enantioselective intramolecular aza‐Michael reaction as ester surrogates. Bifunctional squaramides under microwave irradiation provided the best results in this transformation. Furthermore, this protocol has been combined with a peptide‐coupling reaction in a tandem sequence. The final products were easily converted into the corresponding ethyl esters. 相似文献
999.
Single‐Molecule‐Magnet Behavior in the Family of [Ln(OETAP)2] Double‐Decker Complexes (Ln=Lanthanide,OETAP=Octa(ethyl)tetraazaporphyrin)
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Nelson Giménez‐Agulló Dr. Cristina Sáenz de Pipaón Louis Adriaenssens Dr. Marta Filibian Marta Martínez‐Belmonte Eduardo C. Escudero‐Adán Prof. Pietro Carretta Prof. Pablo Ballester Prof. José Ramón Galán‐Mascarós 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(40):12817-12825
Double‐decker complexes of lanthanide cations can be readily prepared with tetraazaporphyrins (porphyrazines). We have synthesized and characterized a series of neutral double‐decker complexes [Ln(OETAP)2] (Ln=Tb3+, Dy3+, Gd3+, Y3+; OETAP=octa(ethyl)tetraazaporphyrin). Some of these complexes show analogous magnetic features to their phthalocyanine (Pc) counterparts. The Tb3+ and Dy3+ derivatives exhibit single‐molecule magnet (SMM) behavior with high blocking temperatures over 50 and 10 K, respectively. These results confirm that, in double‐decker complexes that involve Tb or Dy, the (N4)2 square antiprism coordination mode has an important role in inducing very large activation energies for magnetization reversal. In contrast with their Pc counterparts, the use of tetraazaporphyrin ligands endows the presented [Ln(OETAP)2] complexes with extraordinary chemical versatility. The double‐decker complexes that exhibit SMM behavior are highly soluble in common organic solvents, and easily processable even through sublimation. 相似文献
1000.
Reversed‐phase high‐performance liquid chromatography method with fluorescence detection to screen nitric oxide synthases inhibitors
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Cristina Maccallini Mauro Di Matteo Alessandra Ammazzalorso Alessandra D'Angelo Barbara De Filippis Sara Di Silvestre Marialuigia Fantacuzzi Letizia Giampietro Assunta Pandolfi Rosa Amoroso 《Journal of separation science》2014,37(12):1380-1385
Nitric oxide synthase (NOS) inhibitors are potential drug candidates due to the critical role of an excessive production of nitric oxide in a range of diseases. At present, the radiometric detection of l ‐[3H]‐citrulline produced from l ‐[3H]‐arginine during the enzymatic reaction is one of the most accepted methods to assess the in vitro activity of NOS inhibitors. Here we report a fast, easy, and cheap reversed‐phase high‐performance liquid chromatography method with fluorescence detection, based on the precolumn derivatization of l ‐citrulline with o‐phthaldialdehyde/N‐acetyl cysteine, for the in vitro screening of NOS inhibitors. To evaluate enzyme inhibition by the developed method, N‐[3‐(aminomethyl)benzyl]acetamidine, a potent and selective inhibitor of inducible NOS, was used as a test compound. The half maximal inhibitory concentration obtained was comparable to that derived by the well‐established radiometric assay. 相似文献