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991.
Saliu F Modugno F Orlandi M Colombini MP 《Analytical and bioanalytical chemistry》2011,401(6):1785-1800
The lipid fractions of residues from historical pharmaceutical ointments were analysed by reversed-phase liquid chromatography
coupled with atmospheric pressure chemical ionization and mass spectrometer detection. The residues were contained in a series
of historical apothecary jars, dating from the eighteenth century and conserved at the “Aboca Museum” in Sansepolcro (Arezzo,
Italy) and at the pharmacy of the “Real Cartuja de Valldemossa” in Palma de Majorca (Spain). The analytical protocol was set
up using a comparative study based on the evaluation of triacylglycerol (TAG) compositions in raw natural lipid materials
and in laboratory-reproduced ointments. These ointments were prepared following pharmaceutical recipes reported in historical
treatises and used as reference materials. The reference materials were also subjected to stress treatments in order to evaluate
the modification occurring in the TAG profiles as an effect of ageing. TAGs were successfully detected in the reproduced formulations
even in mixtures of up to ten ingredients and after harsh degradative treatments, and also in real historical samples. No
particular interferences were detected from other non-lipid ingredients of the formulations. The TAG compositions detected
in the historical ointments indicated a predominant use of olive oil and pig adipose material as lipid ingredients. The detection
of a high level of tristearine and myristyl-palmitoyl-stearyl glycerol in two of the samples suggested the presence of a fatty
material of a different origin (maybe a ruminant). On the basis of the positional isomer ratio, sn-PPO/sn-POP, it was possible to hypothesize an exclusive use of pig fat in one sample. We also evaluated the application of principal
component analysis of TAG profiles as an approach for the multivariate statistical comparison of the reference and historical
ointments. 相似文献
992.
Biarnés X Bongarzone S Vargiu AV Carloni P Ruggerone P 《Journal of computer-aided molecular design》2011,25(5):395-402
Metadynamics is emerging as a useful free energy method in physics, chemistry and biology. Recently, it has been applied also
to investigate ligand binding to biomolecules of pharmacological interest. Here, after introducing the basic idea of the method,
we review applications to challenging targets for pharmaceutical intervention. We show that this methodology, especially when
combined with a variety of other computational approaches such as molecular docking and/or molecular dynamics simulation,
may be useful to predict structure and energetics of ligand/target complexes even when the targets lack a deep binding cavity,
such as DNA and proteins undergoing fibrillation in neurodegenerative diseases. Furthermore, the method allows investigating
the routes of molecular recognition and the associated binding energy profiles, providing a molecular interpretation to experimental
data. 相似文献
993.
Massimiliano D’Arienzo Maurizio Crippa Paolo Gentile Claudio Maria Mari Stefano Polizzi Riccardo Ruffo Roberto Scotti Laura Wahba Franca Morazzoni 《Journal of Sol-Gel Science and Technology》2011,60(3):378-387
Mesoporous Cr or Pt-doped WO3 thin films to be employed as ammonia gas sensors were prepared by a fast one-step sol–gel procedure, based on the use of
triblock copolymer as templating agent. The obtained films were constituted by aggregates of interconnected WO3 nanocrystals (20–50 nm) separated by mesopores with dimensions ranging between 2 and 15 nm. The doping metals, Pt and Cr,
resulted differently hosted in the WO3 mesoporous matrix. Chromium is homogeneously dispersed in the oxide matrix, mainly as Cr(III) and Cr(V) centers, as revealed
by EPR spectroscopy; instead platinum segregated as Pt (0) nanoparticles (4 nm) mainly included inside the WO3 nanocrystals. The semiconductor layers containing Pt nanoclusters revealed, upon exposure to NH3, remarkable electrical responses, much higher than Cr-doped and undoped layers, particularly at low ammonia concentration
(6.2 ppm). This behavior was attributed to the presence of Pt nanoparticles segregated inside the semiconductor matrix, which
act as catalysts of the N–H bond cleavage, decreasing the activation barrier in the ammonia dissociation. The role of the
mesoporous structure in influencing the chemisorption and the gas diffusion in the WO3 matrix appeared less decisive than the electronic differences between the two examined doping metals. The overall results
suggest that a careful combination between mesoporous architecture and metal doping can really promote the electrical response
of WO3 toward ammonia. 相似文献
994.
Maddalena Bronzato Prof. Paolo Calvini Prof. Carlo Federici Prof. Sara Bogialli Prof. Gabriella Favaro Prof. Moreno Meneghetti Prof. Miriam Mba Prof. Marina Brustolon Prof. Alfonso Zoleo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(29):9569-9577
In this work, we present a wide‐range spectrochemical analysis of the degradation products from naturally aged paper. The samples obtained from wash waters used during the de‐acidification treatment of leaves from a 16th‐century‐printed book were analysed through NMR, IR, Raman UV/Vis, EPR and X‐ray fluorescence (XRF) spectroscopy and HPLC‐MS and inductively coupled plasma (ICP) analysis. By these methods we also studied some of the previous samples treated by acidification (sample AP) and catalytic hydrogenation (sample HP). Crossing all the data, we obtained precise indications about the main functional groups occurring on the degraded, water‐soluble cellulose oligomers. These results point out that the chromophores responsible for browning are conjugated carbonyl and carboxyl compounds. As a whole, we show that the analysis of wash waters, used in the usual conservation treatments of paper de‐acidification, gives much valuable information about both the conservation state of the book and the degradation reactions occurring on the leaves, due to the huge amount of cellulose by‐products contained in the samples. We propose therefore this procedure as a new very convenient general method to obtain precious and normally unavailable information on the cellulose degradation by‐products from naturally aged paper. 相似文献
995.
Overall yields better than 90% of pure diphenylacetic acid may be obtained by the route benzilic acid — benzilic acid dimeric ester — diphenylacetic acid. 相似文献
996.
Rino A. Michelin Paolo Sgarbossa Alessandro Scarso Giorgio Strukul 《Coordination chemistry reviews》2010,254(5-6):646-660
The Baeyer–Villiger oxidation of ketones to the corresponding esters or lactones is a valuable transformation that has been upgraded several times over the last century, from the original use of monopersulfuric acid as oxidant to more atom efficient and environmentally friendly oxidants such as hydrogen peroxide. The latter requires activation with organometallic complexes to explicate its oxidizing power. The catalytic version of the reaction can be achieved with several transition metal catalysts, but major differences are present among the various catalysts proposed in terms of scope of the reaction. In particular, most of the catalytic systems are active towards four-membered ring ketones leading to the corresponding substituted γ-butyro-lactones. PtII complexes characterized by the employment of chelating diphosphines turned out to be the most efficient in catalyzing the BV oxidation of a wider range of substrates, in particular cyclohexanones are suitable substrates and acyclic ketones can be converted into the corresponding esters, albeit with low turnover. As long as organometallic catalyzed BV reaction is concerned, PtII catalysts show the most versatile activity and selectivity. Such peculiar features are the result of the unique electronic properties of such metal combined with an easily tailored soft Lewis acid character modulated by the proper choice of the ancillary ligands. The enantioselective version of the reaction benefits from these properties and the compatibility of PtII species with water enabled the development of asymmetric catalytic BV reactions in water aided by the presence of micelles as dynamic self-assembled environments. 相似文献
997.
998.
Nicola D’Antona Raffaele Morrone Paolo Bovicelli Giovanni Gambera David Kubáč Ludmila Martínková 《Tetrahedron: Asymmetry》2010,21(20):2448-2454
A new route to synthesize cyclophellitol and epi-cyclophellitol from racemic starting materials in enantiopure forms has been developed. The synthesis involves a multi-enzymatic biotransformation pathway of the novel cyano-cyclitol (1R,4S,5R,6R)/(1S,4R,5S,6S)-4,5,6-trihydroxycyclohex-2-enecarbonitrile by a cooperative use of lipase, nitrile hydratase, and amidase. 相似文献
999.
Isabel M. Gomez-Monterrey Alessia Bertamino Maria V. Diurno Paolo Grieco 《Tetrahedron》2006,62(34):8083-8088
A novel synthetic route of diaza-bridged heterocycles based on natural 3,9-diazabicyclo[3.3.1]non-6-ene scaffold has been accomplished. The synthetic approach consists of a Pictet-Spengler condensation of the l-Dopa-OMe with an appropriate aldehyde, Fmoc-Aa-H, followed by intramolecular lactamization. This approach generated two configurationally distinct products (cis and trans-isomers), increasing the stereochemical diversity of these compounds. The synthesized compounds are potentially useful in the discovery of novel pharmacologically active compounds. 相似文献
1000.