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41.
The main results of this paper are small-time heat comparison results for two points in two manifolds with characteristic functions as initial temperature distributions
(Theorems 1 and 2). These results are based on the geometric concepts of (essential) distance from the complement and spherical area function. We also discuss some other geometric results about the heat development and illustrate them by examples.
Mathematics subject classifications (2000): 58J35, 35K05 相似文献
42.
The absolute concentrations of iodine, bromine and chlorine in milk, have been determined by epithermal neutron activation followed by high resolution gamma-ray spectrometry. Two kinds of milk commonly consumed in Israel have been investigated. The concentration of iodine, bromine and chlorine were found to be 0.18–0.30 g/ml, 2.02–2.85 g/ml and 0.65 mg/ml, respectively. The method is fast, selective, accurate and highly sensitive. 相似文献
43.
44.
The ability to transport and store a large human blood inventory for transfusions is an essential requirement for medical institutions. Thus, there is an important need for rapid and low-cost characterization tools for analyzing the properties of human red blood cells (RBCs) while in storage. In this study, we investigate the ability to use dielectrophoresis (DEP) for measuring the storage-induced changes in RBC electrical properties. Fresh human blood was collected, suspended in K2-EDTA anticoagulant, and stored in a blood bank refrigerator for a period of 20 days. Cells were removed from storage at 5-day intervals and subjected to a glutaraldehyde crosslinking reaction to “freeze” cells at their ionic equilibrium at that point in time and prevent ion leakage during DEP analysis. The DEP behavior of RBCs was analyzed in a high permittivity DEP buffer using a three-dimensional DEP chip (3DEP) and also compared to measurements taken with a 2D quadrupole electrode array. The DEP analysis confirms that RBC electrical property changes occur during storage and are only discernable with the use of the cell crosslinking reaction above a glutaraldehyde fixation concentration of 1.0 w/v%. In particular, cytoplasm conductivity was observed to decrease by more than 75% while the RBC membrane conductance was observed to increase by more than 1000% over a period of 20 days. These results show that the presented combination of chemical crosslinking and DEP can be used as rapid characterization tool for monitoring electrical properties changes of human RBCs while subjected to refrigeration in blood bank storage. 相似文献
45.
Local existence of solutions to the Euler–Poisson system,including densities without compact support
Local existence and well posedness for a class of solutions for the Euler Poisson system is shown. These solutions have a density ρ which either falls off at infinity or has compact support. The solutions have finite mass, finite energy functional and include the static spherical solutions for . The result is achieved by using weighted Sobolev spaces of fractional order and a new non-linear estimate which allows to estimate the physical density by the regularised non-linear matter variable. Gamblin also has studied this setting but using very different functional spaces. However we believe that the functional setting we use is more appropriate to describe a physical isolated body and more suitable to study the Newtonian limit. 相似文献
46.
Zats GM Arora H Lavi R Yufit D Benisvy L 《Dalton transactions (Cambridge, England : 2003)》2011,40(41):10889-10896
The synthesis and characterisation of the new N,O-phenol-pyrazole pro-ligand, (pz)LH, comprising a pyrazole covalently linked to an o,p-di-tert-butyl-substituted phenol, are herein reported. In CH(2)Cl(2) at room temperature, the cyclic voltammogram (CV) of (pz)LH exhibits a quasi-reversible one-electron oxidation process (at E(1/2) = 0.66 V vs. Fc(+)/Fc) attributed to the formation of the phenoxyl radical cation [(pz)LH]˙(+). (pz)LH reacts with M(II)(BF(4))(2) (M = Cu, Co) in a 2:1 ratio to afford the bis-Cu(pz)L(2) (1) and tris-Co(pz)L(3) (2) complexes respectively. The X-ray structure of 1 reveals a Cu(II) ion in a square-planar trans-Cu(II)-N(2)O(2) coordination environment whereas that of 2 consists of a Co(III) ion with an octahedral mer-N(3)O(3) coordination sphere; formed by the chelation of two (in 1) or three (in 2) N,O-bidentate phenolate ligands respectively. Both structures are preserved in CH(2)Cl(2) solution, as revealed by their NMR (for 2) and EPR (for 1) data. The CVs of 1 and 2 consist of two (at E(1/2): 0.43 and 0.58 V vs. Fc(+)/Fc) and three (E(1/2) = 0.12, 0.54 and 0.89 V vs. Fc(+)/Fc) reversible one-electron oxidation processes, respectively. The one-electron electrochemical oxidation of 1 and 2 produces the oxidised species, 1(+) and 2(+), which are stable for several hours at room temperature under inert atmosphere in CH(2)Cl(2). The UV/vis and EPR data obtained for 1(+) and 2(+) are unambiguously consistent with the latter being formulated as Cu(II)- and Co(III)-phenoxyl radical complexes, as [Cu(II)((pz)L˙)((pz)L)](+) and [Co(III)((pz)L˙)((pz)L)(2)](+) respectively. 相似文献
47.
Rantala A Utriainen M Kaushik N Virta M Välimaa AL Karp M 《Analytical and bioanalytical chemistry》2011,400(4):1041-1049
A bacterial biosensor method for the selective determination of a bioavailable organomercurial compound, methylmercury, is
presented. A recombinant luminescent whole-cell bacterial strain responding to total mercury content in samples was used.
The bacterial cells were freeze-dried and used as robust, reagent-like compounds, without batch-to-batch variations. In this
bacteria-based sensing method, luciferase is used as a reporter, which requires no substrate additions, therefore allowing
homogenous, real-time monitoring of the reporter gene expression. A noninducible, constitutively light-producing control bacterial
strain was included in parallel for determining the overall cytotoxicity of the samples. The specificity of the total mercury
sensor Escherichia coli MC1061 (pmerRBlux) bacterial resistance system toward methylmercury is due to a coexpressed specific enzyme, organomercurial lyase. This enzyme
mediates the cleavage of the carbon–mercury bond of methylmercury to yield mercury ions, which induce the reporter genes and
produce a self-luminescent cell. The selective analysis of methylmercury with the total mercury strain is achieved by specifically
chelating the inorganic mercury species from the sample using an optimized concentration of EDTA as a chelating agent. After
the treatment with the chelating agent, a cross-reactivity of 0.2% with ionic mercury was observed at nonphysiological ionic
mercury concentrations (100 nM). The assay was optimized to be performed in 3 h but results can already be read after 1 h
incubation. Total mercury strain E. coli MC1061 (pmerRBlux) has been shown to be highly sensitive and capable of determining methylmercury at a subnanomolar level in optimized assay
conditions with a very high dynamic range of two decades. The limit of detection of 75 ng/l (300 pM) allows measurement of
methylmercury even from natural samples. 相似文献
48.
Bobin George Abraham Ville Santala Nikolai V. Tkachenko Matti Karp 《Analytical and bioanalytical chemistry》2014,406(28):7195-7204
Monitoring of intracellular redox status in a bacterial cell provides vital information about the physiological status of the cell, which can be exploited in several applications such as metabolic engineering and computational modeling. Fluorescent protein-based genetically encoded sensors can be used to monitor intracellular oxidation/reduction status. This study reports the development of a redox sensor for intracellular measurements using fluorescent protein pairs and the phenomenon of Förster resonance energy transfer (FRET). For the development of the sensor, fluorescent proteins Citrine and Cerulean were genetically modified to carry reactive cysteine residues on the protein surface close to the chromophore and a constructed FRET pair was fused using a biotinylation domain as a linker. In oxidized state, the FRET pairs are in close proximity by labile disulfide bond formation resulting in higher FRET efficiency. In reducing environment, the FRET is diminished due to the increased distance between FRET pairs providing large dynamic measurement range to the sensor. Intracellular studies in Escherichia coli mutants revealed the capability of the sensor in detecting real-time redox variations at single cell level. The results were validated by intensity based and time resolved measurements. The functional immobilization of the fluorescent protein-based FRET sensor at solid surfaces for in vitro applications was also demonstrated. Graphical Abstract
49.
The (n, n′) reaction with the epithermal and fast neutrons of a nuclear reactor has been studied for activation analysis of Sr, Cd, In, Ba, Hf, Os, Au, Hg and Pb. For some elements (In, Os, Au, Hg and Pb) the use of a cadmium sheet reduced the activity by less than a factor of two, while the interferences from the most abundant elements have been reduced by more than two orders of magnitude. 相似文献
50.
The precision of the determination of vanadium in the presence of aluminium by instrumental neutron activation analysis (INAA)
was studied by varying the amount of aluminium in the sample. A precision of ±30% is obtained when the aluminium/vanadium
ratio by weight is ∼350. When the ratio exceeds this value, it is probably desirble to perform a chemical separation prior
to INAA in order to concentrate the vanadium content in the sample. 相似文献