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121.
In this paper, we study the flow of a compressible (density‐gradient‐dependent) non‐linear fluid down an inclined plane, subject to radiation boundary condition. The convective heat transfer is also considered where a source term, similar to the Arrhenius type reaction, is included. The non‐dimensional forms of the equations are solved numerically and the competing effects of conduction, dissipation, heat generation and radiation are discussed. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
122.
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124.
The objective of this study is to utilize the pH sensitivity of modified mesoporous silica nanoparticles (MSN) for oral drug delivery. In the first time, a pH‐sensitive ionic liquid was synthesized through the quaternization of 3‐aminopropyltrimethoxysilane (3‐ATMS) with sodium monochloroacetate (SMCA). Then, silica nanoparticle was modified by this pH‐sensitive ionic liquid and converted to a pH‐sensitive positive‐charge silica nanoparticle (PCSN). The nanoparticle was characterized by FTIR and SEM. Naproxen as anionic drug molecules was entrapped in this pH‐sensitive positive‐charge silica nanoparticles (PCSN) and the in vitro release profiles were established separately in both (SGF, pH 1) and (SIF, pH 7.4). 相似文献
125.
A facile preparation of the title compound by 1,3-dipolar cycloaddition reaction of benzonitrile oxides with isatin imines or isatin diimines, in excellent yield, are reported. 相似文献
126.
Mehrdad Pourayoubi Mahnaz Rostami Chaijan Zdenka Padelková Aleš Ružicka 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):224-231
Abstract In the crystal structure of the title compound C21H24N3OP · C2H5OH, there are three crystallographically independent phosphoric triamide molecules and three ethanol molecules. The environments of the nitrogen atoms are practically planar. The phosphorus atoms display a distorted tetrahedral environment; the maximum and minimum values of angles are observed for one O?P?N and one N?P?N angles, respectively. In this structure, the phosphoramide and ethanol molecules are linked by some different intermolecular O?H···O and N?H···O hydrogen bonds to form chains. The title solvated compound has been further characterized by IR and 31P{1H}, 1H and 13C NMR spectroscopy. The geometry of the nitrogen atoms in this compound is analyzed and compared with those of analogous structures deposited in the Cambridge Structural Database (CSD; Allen, Acta Cryst. 2002, B58, 380-388). 相似文献
127.
Atekeh Tarahhomi Mehrdad Pourayoubi Karla Fejfarov Michal Duek 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(3):225-228
The title complex, trans‐bis(dimethylformamide‐κO)bis{N,N′‐N′′,N′′′‐tetra‐tert‐butyl[oxybis(phosphonic diamide‐κO)]}manganese(II) dichloride dihydrate, [Mn(C16H40N4O3P2)2(C3H7NO)2]Cl2·2H2O, is the first example of a bis‐chelate amido–pyrophosphate (pyrophosphoramide) complex containing an O[P(O)(NH)2]2 fragment. Its asymmetric unit contains half of the complex dication, one chloride anion and one water molecule. The MnII atom, located on an inversion centre, is octahedrally coordinated, with a slight elongation towards the monodentate dimethylformamide ligand. Structural features of the title complex, such as the P=O bond lengths and the planarity of the chelate ring, are compared with those of previously reported complexes with six‐membered chelates involving the fragments C(O)NHP(O), (X)NP(O) [X = C(O), C(S), S(O)2 and P(O)] and O[P(O)(N)2]2. This analysis shows that the six‐membered chelate rings are less puckered in pyrophosphoramide complexes containing a P(O)OP(O) skeleton, such as the title compound. The extended structure of the title complex involves a linear aggregate mediated by N—H...O and N—H...Cl hydrogen bonds, in which the chloride anion is an acceptor in two additional O—H...Cl hydrogen bonds. 相似文献
128.
Banafsheh Vahdani Alviri Mehrdad Pourayoubi Abdul Ajees Abdul Salam Marek Ne
as Arie van der Lee Akshara Chithran Krishnan Damodaran 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(1):104-116
The crystal structures of diphenyl (cycloheptylamido)phosphate, C19H24NO3P or (C6H5O)2P(O)(NHC7H13), ( I ), and diphenyl (dibenzylamido)phosphate, C26H24NO3P or (C6H5O)2P(O)[N(CH2C6H5)2], ( II ), are reported. The NHC7H13 group in ( I ) provides two significant hydrogen‐donor sites in N—H…O and C—H…O hydrogen bonds, needed for a one‐dimensional hydrogen‐bond pattern along [100] in the crystal, while ( II ), with a (C6H5CH2)2N moiety, lacks these hydrogen bonds, but its three‐dimensional supramolecular structure is mediated by C—H…π interactions. The conformational behaviour of the phenyl rings in ( I ), ( II ) and analogous structures from the Cambridge Structural Database (CSD) were studied in terms of flexibility, volume of the other group attached to phosphorus and packing forces. From this study, synclinal (±sc), anticlinal (±ac) and antiperiplanar (±ap) conformations were found to occur. In the structure of ( II ), there is an intramolecular Cortho—H…O interaction that imposes a +sc conformation for the phenyl ring involved. For the structures from the CSD, the +sc and ±ap conformations appear to be mainly imposed by similar Cortho—H…O intramolecular interactions. The large contribution of the C…H/H…C contacts (32.3%) in the two‐dimensional fingerprint plots of ( II ) is a result of the C—H…π interactions. The differential scanning calorimetry (DSC) analyses exhibit peak temperatures (Tm) at 109 and 81 °C for ( I ) and ( II ), respectively, which agree with the strengths of the intermolecular contacts and the melting points. 相似文献
129.
Mehrdad Rezaei Khosrou Abdi Rassoul Dinarvand Sanaz Vosough-Ghanabri Mohsen Amini 《Chromatographia》2009,70(9-10):1491-1494
A gas chromatography-mass spectrometry method for determination of naltrexone in plasma is presented. The method is based on pre-column derivatization of analyte to trimethylsilyl derivative of naltrexone. The analyte and internal standard were extracted from plasma by liquid–liquid extraction. Validation of the method has been studied in the concentration range 1–50 ng mL−1.
相似文献130.
In this work, the intrinsic viscosities of poly(ethylene glycol) with molar mass of 20 kg mol− 1 were measured in water/dimethyl sulfoxide solutions from (298.15 to 318.15) K. The expansion factors of the polymer chains were calculated from the intrinsic viscosity data. The expansion factor were decreased by increasing temperature; therefore the chain of PEG shrinks and the end-to-end distance become smaller by increasing temperature. Perhaps the interactions of segment-segment are favored toward segment-solvent by increasing temperature; therefore the hydrodynamic volumes of the polymer coils become smaller by increasing temperature. The thermodynamic parameters (entropy of dilution parameter, the heat of dilution parameter, theta temperature and polymer-solvent interaction parameter) were derived by the temperature dependence of the polymer chain expansion factor. The thermodynamic parameters indicate that the interactions of segment-segment were increased by increasing temperature. 相似文献