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91.
Luiz-Ferreira A Almeida AC Cola M Barbastefano V Almeida AB Batista LM Farias-Silva E Pellizzon CH Hiruma-Lima CA Santos LC Vilegas W Brito AR 《Molecules (Basel, Switzerland)》2010,15(10):7153-7166
Leaves and bark infusions Anacardium humile St. Hil. (Anacardiaceae), known as in Brazil as "cajuzinho do cerrado", have been used in folk medicine as an alternative treatment for ulcers and gastritis. This study evaluated the gastroprotective activity of an ethyl acetate extract of the leaves of A. humile (AcF) and the mechanism involved in this gastroprotection. Pretreatment concentrations (50, 100, 200 mg x kg?1) were administered by gavage. Following a 60 min. period, all the rats were orally administered 1 mL of absolute ethanol. One hour after the administration of ethanol, all groups were sacrificed, and the gastric ulcer index was calculated. Prostaglandin PGE? concentration, gastric adherent mucous, and the participation of nitric oxide (NO) and sulfhydryl compounds in the gastroprotection process were also analyzed using the most effective tested dose (50 mg x kg?1). A histological study of the glandular stomach for the evaluation of the epithelial damage and mucus content was also performed. AcF significantly reduced the gastric damage produced by ethanol. This effect was statistically significant for the 50 mg x kg?1 group compared to control. Also, it significantly increased the PGE? (by 10-fold) and mucous production, while pretreatment with NG-nitro-L-arginine methyl ester (L-NAME) or N-ethylmaleimide (NEM) completely abolished the gastroprotection. AcF has a protective effect against ethanol, and this effect, might be due to the augmentation of the protective mechanisms of mucosa. 相似文献
92.
Octavio Augusto Novaro María del Alba Pacheco-Blas Juan Horacio Pacheco-Sánchez 《Theoretical chemistry accounts》2010,126(3-4):109-116
A study of nonadiabatic transitions through avoided crossings between two potential energy curves, associated to the approach of a mercury atom to an organic gas molecule (silane or germane) is presented. We study the Si–H and Ge–H bond breaking in the molecules SiH4 and GeH4, which are an important subject in the production of hydrogenated amorphous thin films. We here emphasize the importance of the excited states, the avoided crossings generated during the molecule–metal approach and the nonadiabatic transition probabilities. We have developed a model to extend the Landau–Zener theory utilizing the angle instead of the distance as the main parameter of the reaction, which is particularly adapted for tetrahedral molecules (as silane and germane). The activation process of these molecules requires several stages; first, we solve the Schrödinger equation (within the Born-Oppenheimer approximation) for the metal–molecule system during interaction. We always take into account all those states that can play a role in the reaction, even those that because of their energetic separation from the ground state are forgotten by other groups. The calculations begin at a LCAO-MO approximation and thenceforth variational and perturbative CI including of the order of a million determinants are carried out. Usually, some states of the metal repel the gas molecule and others attract it. This produces a series of avoided crossings among the curves, demanding that the nonadiabatic transition probabilities are obtained. This is the ultimate goal of the present study. 相似文献
93.
94.
Inhibition of peroxyoxalate chemiluminescence by intercalation of fluorescent acceptors between DNA bases 总被引:2,自引:0,他引:2
We have examined the ability of different fluorescent DNA dyes to become chemically excited by the peroxyoxalate chemiluminescent reaction. The intercalating dyes ethidium bromide and propidium iodide, and the bis-intercalating dyes ethidium homodimer-1, benzoxazolium-4-pyridinium dimer-1 and benzoxazolium-4-quinolinium dimer-1, exhibit an intense chemiluminescence when they are excited by the bis(2,4,6-trichlorophenyl)oxalate (TCPO)-H2O2 reaction in the absence of DNA. However, the chemiluminescence of these dyes is very low when they are bound to double-stranded DNA (dsDNA). In contrast, the minor groove-binding dye Hoechst 33258 excited by the TCPO-H2O2 reaction shows approximately the same chemiluminescence intensity when it is free in solution or complexed with dsDNA. Structural alterations or partial dissociation of dsDNA-bis-intercalating dye complexes produced by the addition of acetone, NaCl, MgCl2 or the cationic surfactant cetyltrimethylammonium bromide increases the chemiluminescence intensity. A moderate chemiluminescence intensity is observed when bis-intercalating dyes are complexed with single-stranded DNA. Our results indicate that the energy from the intermediates produced in the peroxyoxalate chemiluminescent reaction cannot be efficiently transferred to fluorescent dyes complexed with DNA; chemiexcitation is almost completely inhibited when dyes are buried in the dsDNA structure by intercalation between the base pairs. 相似文献
95.
In the work reported herein we define a structure validation factor that depends on protein backbone 15N relaxation rates. This is an alternative method to the previously defined quality factors derived from anisotropic chemical shifts or residual dipolar couplings. We have used the structure dependence of 15N relaxation rates of anisotropically tumbling proteins to calculate this structure diagnosis factor and have used it to demonstrate the improvement of protein structures refined with residual dipolar couplings. 相似文献
96.
Alessandro Borghi Roberto Compagnoni Roberto Cossio Lorenzo Giuntini Mirko Massi Filippo Olmi Alba P. Santo Gloria Vaggelli 《Mikrochimica acta》2006,155(1-2):105-112
We present a multi-analytical and multi-instrumental approach to a petrologic study of garnets from metapelites characterized
by different metamorphic grades. The comparison between major, minor and trace element (Y) distribution in garnets crystallized
at different temperatures was performed by electron microprobe (EDS and WDS) and the Proton Induced X-ray Emission microprobe
(μ-PIXE).
Two garnet samples were selected from metapelite rocks at different metamorphic grades from the tectonic unit of Stilo, Calabrian–Peloritanian
Arc, Southern Italy. Quantitative spot analysis profiles and compositional X-ray maps of major elements and yttrium are reported.
The major element zoning of garnets is mostly characterized by a smoothed and gradual concentric variation of all elements
from core to rim. The Y concentration reveals a marked zoning with its distribution decreasing from about 7000 ppm to about
100 ppm from core to rim, respectively. The precise determination of the Y content by μ-PIXE technique allowed us to better
define the rock thermal history, by applying the Y geothermometer. In particular, a common starting temperature of about 450 °C
was calculated for the beginning of the garnet growth from all over the unit, but different temperatures in the range from
520 °C to 670 °C were estimated for the peak event in garnets from different areas, in agreement with the P–T values given
by the main rock mineral assemblages, reflecting a different metamorphic grade. 相似文献
97.
98.
Alba Pons‐Balagué Dr. Stergios Piligkos Dr. Simon J. Teat Dr. Jose Sánchez Costa Muhandis Shiddiq Dr. Stephen Hill Dr. German R. Castro Dr. Pilar Ferrer‐Escorihuela Dr. E. Carolina Sañudo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(27):9064-9071
Microwave‐assisted synthesis has been used to obtain the family of dodecanuclear NiII complexes [Ni12(NO3)(MeO)12(MeC6H4CO2)9(MeOH)10(H2O)2][ClO4]2 ( 1 ), [Ni12(NO3)(MeO)12(BrC6H4CO2)9(MeOH)10(H2O)2][ClO4]2 ( 2 ), [Ni12(CO3)(MeO)12(MeC6H4CO2)9(MeOH)10(H2O)2]2[SO4] ( 3 ) and [Ni12(NO3)(MeO)12(MeC6H4CO2)9(MeOH)8(H2O)7][NO3]2 ( 4 ). They contain three {Ni4O4} cubane units which template around a central μ6 anion, either NO3? or CO32?. Their magnetic properties have been studied by superconducting quantum interference device (SQUID) magnetometry and high‐field EPR measurements. The nanostructuration of the Ni12 species on mica surfaces is studied by AFM and grazing‐incidence X‐ray diffraction, which reveal the formation of polycrystalline thin layers. 相似文献
99.
100.
Frontispiece: Matrix‐Free DNP‐Enhanced NMR Spectroscopy of Liposomes Using a Lipid‐Anchored Biradical 下载免费PDF全文