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361.
The rather long yet variable terminal half-lives and detection times since last use of urinary cannabinoids may partly be attributed to their enterohepatic circulation which generally can be interrupted or restricted by chemical adsorbents. Therefore, an in vitro experiment was performed to study the adsorption/binding of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) and its glucuronide to activated charcoal and wheat bran; remaining concentrations were determined by liquid chromatography/tandem mass spectrometry. Adsorption/binding of 1,000 ng/mL of free or conjugated THC-COOH was complete using as little as 5 mg of charcoal whereas adsorption/binding to wheat bran increased with increasing amounts. Taking of remedies affecting enterohepatic recycling of THC-COOH and its glucuronide may challenge interpretation of cannabinoid concentrations used to detect or assess frequency of drug use or the time since last drug consumption. Figure
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362.
Muntazim Munir Khan Gisela BengtsonSergey Shishatskiy Bahadir N. GacalMd. Mushfequr Rahman Silvio NeumannVolkan Filiz Volker Abetz 《European Polymer Journal》2013
Polymer of Intrinsic Microporosity (i.e. PIM-1) has been crosslinked thermally via nitrene reaction using polyethylene glycol biazide (PEG-biazide) as a crosslinker. The crosslinking temperature was optimized using TGA coupled with FT-IR spectroscopy. The dense membranes containing different ratios of PIM-1 to PEG-biazide were cast from chloroform solution. Crosslinking of PIM-1 renders it insoluble even in excellent solvents for the uncrosslinked polymer. The resulting crosslinked membranes were characterized by FT-IR spectroscopy, TGA and gel content analysis. The influence of crosslinker content on the gas transport properties of PIM-1, its density and fractional free volume (FFV) were investigated. Compared to the pure PIM-1 membrane, the crosslinked PIM-1 membranes showed better gas separation performance especially for CO2/N2, CO2/CH4 and propylene/propane (C3H6/C3H8) gas pairs and as well as suppressed penetrant-induced plasticization under high CO2 pressure. 相似文献
363.
Nuclear Magnetic Resonance Relaxivities: Investigations of Ultrahigh‐Spin Lanthanide Clusters from 10 MHz to 1.4 GHz 下载免费PDF全文
Julyana R. Machado Dr. Amer Baniodeh Prof. Dr. Annie K. Powell Prof. Dr. Burkhard Luy Dr. Steffen Krämer Dr. Gisela Guthausen 《Chemphyschem》2014,15(16):3608-3613
Paramagnetic relaxation enhancement is often explored in magnetic resonance imaging in terms of contrast agents and in biomolecular nuclear magnetic resonance (NMR) spectroscopy for structure determination. New ultrahigh‐spin clusters are investigated with respect to their NMR relaxation properties. As their molecular size and therefore motional correlation times as well as their electronic properties differ significantly from those of conventional contrast agents, questions about a comprehensive characterization arise. The relaxivity was studied by field‐dependent longitudinal and transverse NMR relaxometry of aqueous solutions containing FeIII10DyIII10 ultrahigh‐spin clusters (spin ground state 100/2). The high‐field limit was extended to 32.9 T by using a 24 MW resistive magnet and an ultrahigh‐frequency NMR setup. Interesting relaxation dispersions were observed; the relaxivities increase up to the highest available fields, which indicates a complex interplay of electronic and molecular correlation times. 相似文献
364.
Dr. Pascal Kadjane Prof. Dr. Carlos Platas‐Iglesias Dr. Philipp Boehm‐Sturm Dr. Vincent Truffault Dr. Gisela E. Hagberg Prof. Dr. Mathias Hoehn Prof. Dr. Nikos K. Logothetis Priv.‐Doz. Dr. Goran Angelovski 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(24):7351-7362
Responsive or smart magnetic resonance imaging (MRI) contrast agents are molecular sensors that alter the MRI signal upon changes in a particular parameter in their microenvironment. Consequently, they could be exploited for visualization of various biochemical events that take place at molecular and cellular levels. In this study, a set of dual‐frequency calcium‐responsive MRI agents are reported. These are paramagnetic, fluorine‐containing complexes that produce remarkably high MRI signal changes at the 1H and 19F frequencies at varying Ca2+ concentrations. The nature of the processes triggered by Ca2+ was revealed, allowing a better understanding of these complex systems and their further improvement. The findings indicate that these double‐frequency tracers hold great promise for development of novel functional MRI methods. 相似文献
365.
María A. RamírezMaría V. Corona Gisela OrtizAlejandra Salerno Isabel A. PerilloMaría M. Blanco 《Tetrahedron letters》2011,52(13):1466-1468
A new approach for the synthesis of selectively N-substituted tetra- and pentamethylenediamines 1 (n = 4,5) is described. The method uses N-substituted ω-haloalkanamides 2 as precursors and involves the microwave-promoted conversion into ω-azidocarboxamides 3 and later the reduction of both azido and carboxamide groups with diborane. 相似文献
366.
Germund Höjer Sara Meza-Höjer Gisela Hernández de Pedrero 《Chemical physics letters》1976,37(2):301-306
The orbital order, the bonding properties of the orbitals and the orbital populations are discussed. It is concluded that the orbital order in the valence shell in all the ions is 1a1, 1t2, 2a1, 2t2, 1e, 3t2 and 1t1. The results are compared when possible with experimental data and ab initio results. 相似文献
367.
A new method for the determination of absolute fluorescence quantum yields based on simple relative measurements is described. This energy transfer method is particularly suited for studies of dyes in systems of monomolecular layers. The application of the new method to an investigation of the deactivation of excited thiacyanine dye molecules in monolayers gave evidence for radiationless deactivation processes other than thermal equilibration occurring in higher vibronic levels of the excited singlet state. 相似文献
368.
The acylazide 6, which is readily available from 19,20-dihydromutilin, is thermally decomposed to give the appropriate nitrene. Despite the proximity to the methyl group at C-9 this nitrene inserts regio-and stereospecifically into the C-13-βH bond. The resulting cyclic carbamate 7 is converted in several steps into the formylated amine 11. After introduction of the hererocyclic substituent which was chosen for biological reasons,15,16 followed by a hydride shift,12 the title compound 16 is obtained. 相似文献
369.
Coetzee J Cronje S Dobrzańska L Raubenheimer HG Jooné G Nell MJ Hoppe HC 《Dalton transactions (Cambridge, England : 2003)》2011,40(7):1471-1483
Ylideneamine functionalised heterocyclic ligands, 1,3-dimethyl-1,3-dihydro-benzimidazol-2-ylideneamine (I), 3-methyl-3H-benzothiazol-2-ylideneamine (II) or 3,4-dimethyl-3H-thiazol-2-ylideneamine (III), were employed in the preparation of a series of both charged and neutral gold(I) complexes consisting either of a Au(C(6)F(5)) fragment (1-3), a [Au(PPh(3))](+) unit (4-6) or a [Au(NHC)](+) unit (7) coordinated to the imine nitrogen of the neutral ylideneamine ligand. These complexes were fully characterised by various techniques including X-ray diffraction. In addition, the antitumour and antimalarial potential of selected compounds were assessed in a preliminary study aimed at determining the medicinal value of such compounds. Complexation of the azol-2-ylideneamine ligands with [Au(PPh(3))](+) increases their antitumour as well as antimalarial activity. 相似文献
370.