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881.
Przemysław Sielicki Helena Janik Agnieszka Guzman Alan Reynolds Jacek Namieśnik 《Central European Journal of Chemistry》2011,9(2):308-313
In years 2006–2010 particulate matter analysis was undertaken for dust samples collected from Gdansk and London area in order
to compare their morphology and composition. Part of those studies was devoted to analysis of particulate matter (PM) bearing
metals. Characterization of the morphology and size of the particles collected onto the filters was performed using a scanning
electron microscope (SEM) and transmission electron microscope (TEM). Both electron microscopes were equipped with energy
dispersive X-ray spectrometers to identify the elemental composition of the particles. On analysis of the X-ray spectra acquired
by both TEM and SEM, the particles were divided into 10 groups as follows: Al-rich, Ba-rich, C-rich, Ca-rich, Cl-rich, Fe-rich,
Mg-rich, Na-rich, S-rich, Si-rich. Speciation of the particles based on the major element and accompanying minor elements
yielded 34 particle types. However, some pairs of elements repeat, for instance: Na-Cl and Cl-Na, Al-S and S-Al, Si-Al and
Al-Si, S-Ca and Ca-S. These are undoubtedly the same types of particles; variation in peak heights of the major and minor
elements is normal in a mixed particle population. 相似文献
882.
Grala A Ejfler J Jerzykiewicz LB Sobota P 《Dalton transactions (Cambridge, England : 2003)》2011,40(16):4042-4044
Alkyl-(S,S)-O-lactyllactate was prepared by chemoselective alcoholysis of lactide LA mediated by a magnesium catalyst. When ROH reacted with LA it yielded the ring-opened product R-(S,S)-O-lactyllactate exclusively, which remained intact as long as LA was present in the reaction mixture. Consumption of LA caused the reaction to proceed further giving R-(S)-lactate. 相似文献
883.
Kellett A O'Connor M McCann M McNamara M Lynch P Rosair G McKee V Creaven B Walsh M McClean S Foltyn A O'Shea D Howe O Devereux M 《Dalton transactions (Cambridge, England : 2003)》2011,40(5):1024-1027
Three, structurally characterised, bis-phen Cu(II) complexes of the phthalate isomers display rapid, low micromolar in vitro cytotoxicity against a range of epithelial tumour cells. The complexes induce relaxation of supercoiled plasmid DNA in the absence of external reducing agents and display efficient CT-DNA, Poly[d(A-T)](2) and Poly[d(G-C)](2) binding. 相似文献
884.
Purcaro G Quinto Tranchida P Conte L Obiedzińska A Dugo P Dugo G Mondello L 《Journal of separation science》2011,34(18):2411-2417
The performance of a novel rapid-scanning (20,000 amu/s) quadrupole mass spectrometer (qMS) has been evaluated in the comprehensive 2-D gas chromatography (GC×GC) analysis of pesticides contained in water. Analyte extraction was performed by using direct solid-phase microextraction (SPME). The MS system was operated using a rather wide m/z 50-450 mass range and a 33 Hz spectral production rate, a frequency which was found sufficient for reliable quantification. The qMS performance was evaluated considering: (i) number of data points per peak, (ii) mass spectral quality, (iii) extent of peak skewing, and (iv) consistency of retention times. Seven-point calibration curves (external calibration) were constructed for 28 pesticides over the limit of quantification range of 100 μg/L (1, 5, 10, 25, 50, and 100 μg/L). The solid-phase microextraction-GC×GC-qMS method was validated by calculating limits of detection and quantification, intraday peak area precision, accuracy, and intraday retention-time precision. A series of tap water samples were subjected to analysis, fortunately giving negative results. 相似文献
885.
Więckowska A Jabłonowska E Rogalska E Bilewicz R 《Physical chemistry chemical physics : PCCP》2011,13(20):9716-9724
The effect of a lipolytic enzyme, pork pancreatic phospholipase A(2), on hybrid bilayer membranes was monitored using voltammetry, impedance spectroscopy and surface plasmon resonance. The hybrid bilayers were prepared by Langmuir-Schaefer transfer of lipid monolayers onto gold electrodes modified with self-assembled alkanethiol monolayers, or by liposome spreading. The electrodes were immersed in the phospholipase aqueous solution to allow adsorption of the enzyme and cleavage of the ester bond in the sn-2 position of phospholipids in the outer leaflet of the hybrid layers. The action of phospholipase A(2) led to perforation of the lipid films. Impedance spectroscopy and surface plasmon resonance were used for monitoring enzyme adsorption, phospholipid hydrolysis and product desorption. The results obtained show that transport efficiency of an electroactive probe, ferrocyanate, and of an electroactive drug, doxorubicin, through the bilayer depends on the action of the enzyme; the state of the lipid layer covering the electrode surface depends on the latter as well. Cyclic voltammetry and electrochemical impedance spectroscopy were used to study this effect. The doxorubicin reduction/oxidation signals appearing at potentials close to those observed using a bare gold electrode indicated facilitated penetration of the drug into the layer. The results obtained were interpreted in terms of pore formation in the lipid matrix; phospholipase A(2) can be considered as a nano-device for high precision perforation of the lipid layer. 相似文献
886.
Góra RW Zaleśny R Zawada A Bartkowiak W Skwara B Papadopoulos MG Silva DL 《The journal of physical chemistry. A》2011,115(18):4691-4700
We report the partitioning of the interaction-induced static electronic dipole (hyper)polarizabilities for linear hydrogen cyanide complexes into contributions arising from various interaction energy terms. We analyzed the nonadditivities of the studied properties and used these data to predict the electric properties of an infinite chain. The interaction-induced static electric dipole properties and their nonadditivities were analyzed using an approach based on numerical differentiation of the interaction energy components estimated in an external electric field. These were obtained using the hybrid variational-perturbational interaction energy decomposition scheme, augmented with coupled-cluster calculations, with singles, doubles, and noniterative triples. Our results indicate that the interaction-induced dipole moments and polarizabilities are primarily electrostatic in nature; however, the composition of the interaction hyperpolarizabilities is much more complex. The overlap effects substantially quench the contributions due to electrostatic interactions, and therefore, the major components are due to the induction and exchange-induction terms, as well as the intramolecular electron-correlation corrections. A particularly intriguing observation is that the interaction first hyperpolarizability in the studied systems not only is much larger than the corresponding sum of monomer properties, but also has the opposite sign. We show that this effect can be viewed as a direct consequence of hydrogen-bonding interactions that lead to a decrease of the hyperpolarizability of the proton acceptor and an increase of the hyperpolarizability of the proton donor. In the case of the first hyperpolarizability, we also observed the largest nonadditivity of interaction properties (nearly 17%) which further enhances the effects of pairwise interactions. 相似文献
887.
Grzegorz Mloston Emilia Obijalska Agnieszka Tafelska-Kaczmarek 《Journal of fluorine chemistry》2010,131(12):1289-833
The reactions of α-imino ketones, derived from arylglyoxals, with (trifluoromethyl)trimethylsilane (CF3SiMe3) in DME solution, in the presence of catalytic amount of CsF, at room temperature, yield O-silylated β-imino alcohols in the chemoselective manner. Subsequent reduction of these products with NaBH4 in ethanolic solution leads to the corresponding β-(N-alkyl)amino-α-trifluoromethyl alcohols in good to excellent yields. Trifluoromethylation of enantiomerically pure α-imino ketones (with Ar = Ph or p-MeOC6H4), bearing as a chiral auxiliary the PhCH(Me) group attached to the nitrogen atom, yields mixtures of diastereomeric products in the ratio of ca. 3:2. 相似文献
888.
Carbanions of 3-substituted-3-chloropropyl phenyl sulfones add to carbonyl groups of aldehydes to produce aldol type adducts that undergo 1,5-intramolecular substitution giving 2,3,5-trisubstituted tetrahydrofurans. The effect of substituents in the 3-position of these sulfones on the relative rates of 1,3-intramolecular substitution of the corresponding γ-chlorocarbanions and their intramolecular addition are disclosed. 相似文献
889.
Nina-Luisa Michels Agnieszka Kapałka A.A. Abd-El-Latif Helmut Baltruschat Christos Comninellis 《Electrochemistry communications》2010,12(9):1199-1202
Electrochemical oxidation of ammonia (NH3 and NH4 + ) on boron-doped diamond (BDD) electrode was studied using differential electrochemical mass-spectrometry (DEMS) and chronoamperometry. Electro-oxidation of ammonia induces inhibition of the oxygen evolution reaction (OER) due to adsorption of the ammonia oxidation products on the BDD surface. The inhibition of the OER enhances ammonia electro-oxidation, which becomes the main reaction. The amino radicals, formed during ammonia oxidation, trigger a reaction chain in which molecular oxygen dissolved in solution is involved in the ammonia electro-oxidation. Nitrogen, nitrous oxide, and nitrogen dioxide were detected as the ammonia oxidation products, with nitrogen being the main gaseous product of the oxidation. 相似文献
890.
Agnieszka Kapałka Alexandros Katsaounis Nina-Luisa Michels Anna Leonidova Stamatis Souentie Christos Comninellis Kai M. Udert 《Electrochemistry communications》2010,12(9):1203-1205
The electrochemical oxidation of ammonia (NH3 and/or NH4+) in the presence of chloride was investigated on a Ti/PtOx–IrO2 electrode. It was shown that ammonia is effectively removed from solution via electrogenerated active chlorine. Based on mass balances, nitrogen is postulated to be the main product of ammonia electrolysis. In the bulk, the concentration of chloramines was low. This could be explained by the fact that the oxidation of ammonia takes place close to the electrode surface where an excess of chlorine relative to ammonia is ensured during the process. This results in the oxidation of ammonia to N2 and in a local pH decrease. As a result, chloramines were decomposed in the proximity of the electrode prior to diffusing into the bulk. 相似文献