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201.
Groenendaal B Vugts DJ Schmitz RF de Kanter FJ Ruijter E Groen MB Orru RV 《The Journal of organic chemistry》2008,73(2):719-722
An efficient, one-pot synthetic protocol toward triazinane diones, a rather unexplored class of heterocyclic scaffolds combining phosphonates, nitriles, aldehydes, and isocyanates is described. The optimization of the reaction, synthesis of a small library of different triazinane diones, as well as alternative routes toward the triazinane dione scaffold are discussed. 相似文献
202.
The relation between the self-diffusion coefficient, Dself, of water and the free volume hole size, Vh, has been investigated in a hydroxypropyl methylcellulose (HPMC)-water system in the water content range 0.08-0.36 w/w, at room temperature. Furthermore, the thermal properties of the water in the HPMC-water system, as measured with differential scanning calorimetry (DSC) and the tensile storage, E′, and tensile loss, E″, moduli, of the HPMC-water systems, as determined with dynamic mechanical analysis (DMA), have been probed. Pulsed-field gradient nuclear magnetic resonance (PFG NMR) was used to measure the Dself of water and positron annihilation lifetime spectroscopy (PALS) was used to measure the ortho-Positronium (o-Ps) lifetime in the HPMC-water system. The glass transition temperature of the HPMC was found to be reduced by the water to room temperature in the water content range 0.10-0.15 w/w. The relation between ln Dself of water and the inverse free volume hole size of the HPMC-water system was non-linear. Furthermore, the PALS measurements showed that molecular water co-existed with water clusters in the HPMC-water system. 相似文献
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Jungmann JH MacAleese L Buijs R Giskes F de Snaijer A Visser J Visschers J Vrakking MJ Heeren RM 《Journal of the American Society for Mass Spectrometry》2010,21(12):2023-2030
In mass spectrometry imaging, spatial resolution is pushed to its limits with the use of ion microscope mass spectrometric
imaging systems. An ion microscope magnifies and then projects the original spatial distribution of ions from a sample surface
onto a position-sensitive detector, while retaining time-of-flight mass separation capabilities. Here, a new type of position-sensitive
detector based on a chevron microchannel plate stack in combination with a 512 × 512 complementary metal-oxide-semiconductor
based pixel detector is coupled to an ion microscope. Spatial resolving power better than 6 μm is demonstrated by secondary
ion mass spectrometry and 8–10μm spatial resolving power is achieved with laser desorption ionization. A detailed evaluation
of key performance criteria such as spatial resolution, acquisition speed, and data handling is presented. 相似文献
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H. Monique H. Hurks Coby Out-Luiting Bert-Jan Vermeer Frans H. J. Claas A. Mieke Mommaas 《Photochemistry and photobiology》1997,66(1):76-81
Abstract— The mixed epidermal cell lymphocyte reaction (MECLR) is a commonly used method to study the immunomodulatory effects of UV radiation. The in vitro action spectrum for the MECLR showed that the UV-induced suppression of the MECLR responses is associated with UV-induced DNA damage. To investigate whether in vivo DNA damage also leads to the abrogation of the MECLR, in situ action spectra were made for the MECLR and the induction of thymine dimers (T<>T). Human skin, obtained from plastic surgery, was exposed to monochromatic light of 254, 297, 302 and 312 nm. After irradiation, epidermal cells were isolated and used as stimulator cells in the MECLR or processed for flow cytometric detection of T<>T. On the basis of dose-response curves for each wavelength, the action spectra for suppression of the MECLR and the induction of T<>T were calculated. These spectra showed close similarities, suggesting that, also in situ, UV-induced DNA damage is involved in the UV-induced suppression of the MECLR. Both action spectra showed a small decline from 254 nm to 302 nm, followed by a steep decline to 312 nm. These data show that, in situ, UVC can efficiently induce DNA damage and modulate cutaneous immune responses. 相似文献
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Johannes H. Sterba Frans Munnik Nick J. G. Pearce 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(1):25-35
Provenancing of ancient ceramics is a highly important scientific tool for archaeological studies. In general, ceramics are
not made from the original clay as it is found in deposits. To produce the needed physical properties in the finished product,
the clay has to be either tempered by adding sands or biological materials, or levigated, to remove the coarse fraction. Thus,
the chemical composition of the finished ceramic differs from the composition of the original clay bed. To overcome this obfuscation,
any information that can be gained about the temper is useful. In a small series, several pieces of ceramic were produced
from known clay and tempers and the resulting ceramics analysed by neutron activation analysis (NAA). As many attempts to
physically separate the temper from the clay matrix have failed, μ-spot analysis of temper inclusions was performed at the
microbeam particle induced X-ray Emission (μ-PIXE) facility in Rossendorf and with laser ablation inductively coupled plasma
mass spectroscopy (LA-ICP-MS) at the Aberystwyth University in Wales. It could be shown that from a small number of measurements,
a general impression of the temper used could be gained. Furthermore the μ-spot methods and the bulk data gained from INAA
are highly comparable, extending the set of elements that can be measured. With this information, the influence of the temper
on the bulk composition of the finished product can be estimated, which potentially adds crucial information to subsequent
dilution calculations. 相似文献