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451.
Andrej Osterc 《International journal of environmental analytical chemistry》2013,93(5):553-564
129I is important as an environmental tracer of the biogeochemical cycling of iodine and of the dissemination of nuclear pollution, because anthropogenic 129I has been released from only few point sources and with its short mixing time its distribution therefore reveals the movement of 129I in the environment. A radiochemical neutron activation analysis method was developed to measure the concentration of 129I in soil samples. A procedure to pre-concentrate iodine from up to 150?g of soil was developed and validated using IAEA standard reference material IAEA-375 (Chernobyl soil). The method was applied to determine 129I/127I isotopic ratios as well as 129I and 127I concentrations in soils from several locations in Ukraine collected in 2006, 1996, 1993 and 1989, and from Slovenia, collected at various places in 2009 and 2006. The 127I concentrations in surface soils from Ukraine were in the range 2.3–23.1?µg?g?1 and for 129I (11.1–245.7)?·?10?8?µg?g?1 dry matter with the highest value of 1.47?·?10?3?µg?g?1 found in a soil sample collected in Yaniv, Ukraine in July 1993. In soil samples from Slovenia 127I concentrations ranged 0.73–130?µg?g?1 and 129I (8.0–245.7)?·?10?8?µg?g?1. The 129I/127I isotopic ratios of surface soils from Ukraine were in the range of the order of 10?9–10?5 and of 10?10–10?8 for soils from Slovenia. The highest isotopic ratio 13.6?·?10?5 was found in a soil sample collected in Yaniv, Ukraine in July 1993. 相似文献
452.
Polonca Trebše Boris Recelj Tanja Lukanc Simona Golič Grdadolnik Andrej Petrič Bojan Verček 《合成通讯》2013,43(15):2637-2644
6, 7-Dihydrocyclopenta[b]pyran-2, 5-dione 1 was converted with hydrazines to fused pyridine-2(1H)-ones of type a. In contrast, 2H-1-benzopyran-2, 5-diones 2–4 gave under the same reaction conditions 5-hydrazonobenzopyrans of type b. Calculated heats of formation matched experimental findings. 相似文献
453.
In situ photoexcitation of silver-doped titania nanopowders for activity against bacteria and yeasts
Kowal K Wysocka-Król K Kopaczyńska M Dworniczek E Franiczek R Wawrzyńska M Vargová M Zahoran M Rakovský E Kuš P Plesch G Plecenik A Laffir F Tofail SA Podbielska H 《Journal of colloid and interface science》2011,362(1):50-57
Photocatalytic and in situ microbial activity of the amorphous and annealed states of Ag-doped and un-doped titania were examined. Studies on their structure, morphology, composition, and the photo-absorption characteristics of these materials were performed. These results were correlated with the photocatalytic and microbial activity against methicillin resistant Staphylococcus aureus K324 (MRSA), methicillin susceptible S. aureus ATCC 25923 (MSSA), Escherichia coli PA 170, and yeasts Candida albicans ATCC 90028. The annealed powders containing anatase form of titania exhibited relatively higher photocatalytic activity,corresponding to activity against MRSA,when exposed to UV-A radiation. In comparison, amorphous powders exhibited low photoactivity and showed poor antibacterial performance against MRSA under UV-A exposure. Doping of amorphous titania with Ag resulted in an anti-MRSA effect without exposure to UV radiation. In the Ag-doped crystalline anatase samples, the size of Ag primary nanocrystallites increased, which led to the decrease in the surface concentration of Ag and detriment anti-MRSA activity. 相似文献
454.
Edelson-Averbukh M Shevchenko A Pipkorn R Lehmann WD 《Journal of the American Society for Mass Spectrometry》2011,22(12):2256-2268
Unambiguous differentiation between isobaric sulfated and phosphorylated tyrosine residues (sTyr and pTyr) of proteins by mass spectrometry is challenging, even using high resolution mass spectrometers. Here we show that upon negative ion mode collision-induced dissociation (CID), pTyr- and sTyr-containing peptides exhibit entirely different modification-specific fragmentation patterns leading to a rapid discrimination between the isobaric covalent modifications using the tandem mass spectral data. This study reveals that the ratio between the relative abundances of [M-H-80](-) and [M-H-98](-) fragment ions in ion-trap CID and higher energy collision dissociation (HCD) spectra of singly deprotonated +80 Da Tyr-peptides can be used as a reliable indication of the Tyr modification group nature. For multiply deprotonated +80 Da Tyr-peptides, CID spectra of sTyr- and pTyr-containing sequences can be readily distinguished based on the presence/absence of the [M-nH-79]((n-1)-) and [M-nH-79-NL]((n-1)-) (n=2, 3) fragment ions (NL=neutral loss). 相似文献
455.
Measurement of the appearance of an object consists of a group of measurements to characterize the color and surface finish
of the object. This group of measurements involves the spectral energy distribution of propagated light measured in terms
of reflectance and transmittance, and the spatial energy distribution of that light measured in terms of the bidirectional
reflectance distribution function (BRDF). In this article we present the virtual gonio-spectrophotometer, a device that measures
flux (power) as a function of illumination and observation. Virtual gonio-spectrophotometer measurements allow the determination
of the scattering profile of specimens that can be used to verify the physical characteristics of the computer model used
to simulate the scattering profile. Among the characteristics that we verify is the energy conservation of the computer model.
A virtual gonio-spectrophotometer is utilized to find the correspondence between industrial measurements obtained from gloss
meters and the parameters of a computer reflectance model. 相似文献
456.
Structural properties of effective potential model by liquid state theories 总被引:1,自引:0,他引:1 下载免费PDF全文
This paper investigates the structural properties of a model fluid dictated by an effective inter-particle oscillatory potential by grand canonical ensemble Monte Carlo (GCEMC) simulation and classical liquid state theories.The chosen oscillatory potential incorporates basic interaction terms used in modeling of various complex fluids which is composed of mesoscopic particles dispersed in a solvent bath,the studied structural properties include radial distribution function in bulk and inhomogeneous density distribution profile due to influence of several external fields.The GCEMC results are employed to test the validity of two recently proposed theoretical approaches in the field of atomic fluids.One is an Ornstein-Zernike integral equation theory approach;the other is a third order + second order perturbation density functional theory.Satisfactory agreement between the GCEMC simulation and the pure theories fully indicates the ready adaptability of the atomic fluid theories to effective model potentials in complex fluids,and classifies the proposed theoretical approaches as convenient tools for the investigation of complex fluids under the single component macro-fluid approximation. 相似文献
457.
Dominika Valachová Michaela Marčeková Dr. Oľga Caletková Dr. Andrej Kolarovič Dr. Pavol Jakubec 《European journal of organic chemistry》2023,26(13):e202201341
Protodenitration, a direct reduction of nitroalkanes to corresponding alkanes, already spans two centuries and is enabled by various reagents. This mini-review provides a historical development of the fundamental transformation and highlights the governing position of the Ono-Tanner reaction employing tributyltin hydride. Due to the unchallenged dominance of the toxic tributyltin hydride and environmentally unpopular solvents sharply contrasting with modern ecological trends, the current situation was dubbed “the last fortress of tin's tyranny.” 相似文献
458.
Čegovnik Tomaž Dobrovoljc Andrej Povh Janez Rogar Matic Tomšič Pavel 《Central European Journal of Operations Research》2023,31(3):833-851
Central European Journal of Operations Research - The measurement of electricity consumption at 15-minute granularity, including for households, is increasingly mandated in the EU and this also... 相似文献
459.
A statistical theory of conjugated macro- and microphase separation in flexile polydisperse block copolymer systems with a given arbitrary molecular structural distribution is developed in the mean field approximation. A special attention is paid to recognizing and calculating all terms having the least order of magnitude to be taken into account. To this end a special procedure is elaborated enabling to distinguish between strongly and weakly fluctuating order parameters characterizing polydisperse systems and to construct explicitly a one-field parametrization of the free energy of the systems under investigation. The contribution of so-called higher harmonics and effect of a redistribution of macromolecules among coexisting phases are taken into account therewith by a proper renormalization of the fourth vertex of the corresponding effective hamiltonian. In order to compare the presented approach and other existing theories phase diagrams of molten polydisperse diblock copolymer are built numerically in approximations corresponding to different theories. It is shown that our rigorous approach results in phase diagrams qualitatively different from the conventional ones. In particular, we predict the existence of one-phase region having a quasicrystal symmetry and regions of coexistence of this phase with disordered phase and one having the symmetry of the body-centered-oubic lattice as well as a considerable shrinking of the region of the existence of the lamellar phase. 相似文献