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81.
An automated turbidimetric method was developed for group level identification of penicillinase sensitive penicillins, tetracyclines and fluoroquinolones in kidney samples. A sample pretreatment procedure was elaborated for the extraction of incurred residues from kidney tissue in a translucent solution to enable the measurement of changes in optical density. The method was comprised of three pairs, one for each antibiotic group: a sensitive test bacterium strain and a resistant strain for the identification of fluoroquinolones and tetracyclines, and a sensitive strain with and without penicillinase for the identification of penicillinase sensitive penicillins. The algorithm employed compared the areas under the OD vs. time curves; threshold values and experimentally observed intra-test criteria were also included in the algorithm. Antibiotics were reliably identified to group level, and no false identifications were obtained with antibiotics belonging to groups not included in the reference panel. Incurred penicillin G, oxytetracycline and enrofloxacin-ciprofloxacin residues were identified at or below the MRL levels for kidney tissue. The graphically determined shortest possible identification times varied between 2 and 7 h. The method developed could furthermore easily be diversified to include other antibiotic groups by adding new "sensitive-resistant" bacterium and medium combinations. 相似文献
82.
Clemente-Juan JM Coronado E Gaita-Ariño A Giménez-Saiz C Güdel HU Sieber A Bircher R Mutka H 《Inorganic chemistry》2005,44(10):3389-3395
The magnetic exchange interactions in a C0(3)(11) moiety encapsulated in Na(17) [(NaOH(2))Co(3)(H(2)O)(P(2)W(15)O(56))(2)] (NaCo(3)) were studied by a combination of magnetic measurements (magnetic susceptibility and low-temperature magnetization), with a detailed Inelastic Neutron Scattering (INS) investigation. The novel structure of the salt was determined by X-ray crystallography. The ferromagnetic Co(3)O(14) triangular cluster core consists of three octahedrally oxo-coordinated Co(II) ions sharing edges. According to the single-ion anisotropy and spin-orbit coupling usually assumed for octahedral Co(II) ions, the appropiate exchange Hamiltonian to describe the ground-state properties of the isosceles triangular Co(3) spin cluster is anisotropic and is expressed as H = - 2sigma(alpha)(=)(x,y,z)(J(alpha)(12)S(1alpha)S(2alpha) + J(alpha)(23)S(2alpha)S(3alpha) + J(alpha)(13)S(1alpha)S(3alpha)), where J(alpha) are the components of the exchange interactions between the Co(II) ions. To reproduce the INS data, nonparallel anisotropic exchange tensors needed to be introduced, which were directly connected to the molecular symmetry of the complex. The following range of parameters (value +/- 0.5 cm(-1)) was found to reproduce all experimental information while taking magnetostructural relations into account: J(x)(12) = J(y)(13) = 8.6 cm(-1); J(y)(12) = J(x)(13) = 1.4 cm(-1); J(z)(12) = J(z)(13) = 10.0 cm(-1); J(x)(23) = J(y)(23) = 6.5 cm(-1) and = 3.4 cm(-1). 相似文献
83.
Välimaa L Ylikotila J Kojola H Soukka T Takalo H Pettersson K 《Analytical and bioanalytical chemistry》2008,391(6):2135-2144
Direct measurement of time-resolved fluorescence from a washed surface of an immunoassay well constitutes an advantage compared
with label development options involving signal generation in solution. Epi-fluorometric detection collects the signal from
only a small part of the microtiter well’s bottom surface and it is inadequate for the optimal assay sensitivity when using
binding surfaces introduced by large coating volume. This study reports on the use of streptavidin-coated spots intended to
condense the binding of the labeled antibodies to coincide with the excitation beam. The spots were generated in special microtiter
wells containing 2.5-mm, 3.5-mm, and 4.5-mm diameter indentations by adsorption from liquid droplets containing either native
(SAv) or modified high-capacity (GA-SAv) streptavidin. The SAv-coated and GA-SAv-coated spots exhibited maximum Eu–biotin
binding densities of 0.080 and 0.47 pmol/mm2, respectively. A sandwich-type immunoassay of thyroid-stimulating hormone (TSH) provided a fivefold to sixfold increase in
the signal-to-background ratios of the spot assay and an equivalent improvement in the detection limit (DL < 0.01 mU/L) compared
with a reference assay.
Figure The condensation of the binding area into a spot (right) results in a denser collection of the labeled antibodies and more favorable signal-to-background ratios compared with a
regular approach using a large binding area (left) 相似文献
84.
Characteristics of muon pair production in very high energy nucleus-nucleus collisions are discussed. Particular attention is given to comparing the rate of muon pairs produced from thermalized quark-gluon matter to that of pairs produced via the usual Drell-Yan mechanism. The thermal rate is at least of the same order of magnitude as the direct Drell-Yan rate and will certainly dominate whenx F for the pair approaches 1. Beyondx F =1 the thermal rate is also substantial. This region is particularly easily accessible in fixed target experiments. 相似文献
85.
86.
87.
A surface-sensitive fluorescence measurement platform is utilised in the detection of morphine. The platform is based on a
polystyrene parabolic lens that enables the simultaneous application of total internal reflection excitation and supercritical
angle fluorescence detection in the measurements. The molecular recognition of morphine is based on two antibodies, one against
morphine and the other against the immune complex formed between the anti-morphine antibody and a morphine molecule. The antibodies
are applied in a sandwich-like format in a one-step test, where the molecular binding onto a liquid-solid-interface is monitored
in real time. Morphine concentrations between 0.6 and 18.2 ng/mL were reliably determined in 60 s, while concentrations down
to 2.7 ng/mL were detected already in 20 s. With appropriate recognition molecules the technique is applicable also to other
drugs and small analytes. 相似文献
88.
89.
We consider five different peer-to-peer file-sharing systems with two chunks, assuming non-altruistic peers who leave the
system immediately after downloading the second chunk. Our aim is to find chunk selection algorithms that have provably stable
performance with any input rate. We show that many algorithms that first looked promising lead to unstable or oscillating
behaviour. However, we end up with a system with desirable properties. Most of our rigorous results concern the corresponding
deterministic large system limits, but in the two simplest cases we provide proofs for the stochastic systems also. 相似文献
90.
Katja Vähävihu Lasse Ylianttila Hannu Kautiainen Pentti Tuohimaa Timo Reunala Erna Snellman 《Photochemistry and photobiology》2010,86(5):1174-1178
The objective of the study was to compare Bacillus subtilis spore film dosimeters with a Robertson Berger UV meter (RB meter) and diary records for assessing personal UV-B doses during a 13-day heliotherapy (HT) for atopic dermatitis (AD). In addition, the relationship between the personal UV-B dose and change in serum 25-hydroxyvitamin D (25(OH)D) was studied. Altogether 21 adult patients with AD completed the study arranged in the Canary Islands, either in January or March 2005. The spore film dosimeters were used throughout the day during the HT. Serum 25(OH)D was analyzed using radioimmunoassay. The mean personal UV-B dose measured with the dosimeters was 75 SED in January and 131 SED in March. The respective results gained from the RB meter combined with diary records were 63 SED and 119 SED showing a close correlation with the dosimeter results. Serum 25(OH)D concentration increased by 9.7 nmol L−1 in January and by 26.0 7 nmol L−1 in March. The increase in serum 25(OH)D correlated with the UV-B dose received. The patients complied well to use the dosimeters. We conclude spore films to be a feasible and reliable personal UV dosimeter in vivo in field conditions. 相似文献