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排序方式: 共有354条查询结果,搜索用时 15 毫秒
61.
This paper presents an ADBASE-based parallel algorithm forsolving multiple objective linear programs (MOLPs). Job balance,speedup and scalability are of primary interest in evaluatingefficiency of the new algorithm. The scalability of a parallelalgorithm is a measure of its capacity to increase performance withrespect to the number of processors used. Implementation results onIntel iPSC/2 and Paragon multiprocessors show that the algorithmsignificantly speeds up the process of solving MOLPs, which isunderstood as generating all or some efficient extreme points andunbounded efficient edges. The algorithm is shown to be scalable andgives better results for large problems. Motivation andjustification for solving large MOLPs are also included. 相似文献
62.
Zurowski Radoslaw Gluszek Malgorzata Antosik Agnieszka Pietrzak Emilia Rokicki Gabriel Szafran Mikolaj 《Journal of Thermal Analysis and Calorimetry》2018,133(1):453-463
Journal of Thermal Analysis and Calorimetry - To study the effect of ionic liquids (ILs) of the microstructure on the surface of the coal, four ILs ([Emim][BF4], [Bmim][BF4], [Bmim][NO3], and... 相似文献
63.
Vakrat-Haglili Y Weiner L Brumfeld V Brandis A Salomon Y McLlroy B Wilson BC Pawlak A Rozanowska M Sarna T Scherz A 《Journal of the American Chemical Society》2005,127(17):6487-6497
Generation of reactive oxygen species (ROS) is the hallmark of important biological processes and photodynamic therapy (PDT), where ROS production results from in situ illumination of certain dyes. Here we test the hypothesis that the yield, fate, and efficacy of the species evolved highly depend on the dye's environment. We show that Pd-bacteriopheophorbide (Pd-Bpheid), a useful reagent for vascular targeted PDT (VTP) of solid tumors, which has recently entered into phase II clinical trials under the code name WST09 (trade name TOOKAD), forms appreciable amounts of hydroxyl radicals, superoxide radicals, and probably hydrogen peroxide in aqueous medium but not in organic solvents where singlet oxygen almost exclusively forms. Evidence is provided by pico- and nanosecond time-resolved spectroscopies, ESR spectroscopy with spin-traps, time-resolved singlet oxygen phosphorescence, and chemical product analysis. The quantum yield for singlet oxygen formation falls from approximately 1 in organic solvents to approximately 0.5 in membrane-like systems (micelles or liposomes), where superoxide and hydroxyl radicals form at a minimal quantum yield of 0.1%. Analysis of photochemical products suggests that the formation of oxygen radicals involves both electron and proton transfer from (3)Pd-Bpheid at the membrane/water interface to a colliding oxygen molecule, consequently forming superoxide, then hydrogen peroxide, and finally hydroxyl radicals, with no need for metal catalysis. The ability of bacteriochlorophyll (Bchl) derivatives to form such radicals upon excitation at the near infrared (NIR) domain opens new avenues in PDT and research of redox regulation in animals and plants. 相似文献
64.
The presented results show the usefulness of Raman spectroscopy in the investigation of polyacetylenes in carrot root. The components are measured directly in the plant tissue without any preliminary sample preparation. Compared with the strong polyacetylene signals the spectral impact of the surrounding biological matrix is weak, except for carotenoids, and therefore it does not contribute significantly to the obtained results. Three different Raman mapping techniques applied here have revealed essential information about the investigated compounds. Using point acquisition several spectra have been measured to demonstrate the complex composition of the polyacetylene fraction in carrot root. The molecular structures of falcarinol, falcarindiol and falcarindiol 3-acetate are similar but their Raman spectra exhibit differences demonstrated by the shift of their -C triple bond C- mode. Line mapping performed along the diameter of transversely cut carrot roots has been used to investigate the relative concentration of polyacetylenes and carotenoids. An area map provides detailed information regarding the distribution of both components. It has been found that high accumulation of polyacetylenes is located in the outer section of the root, namely the pericyclic parenchyma, and in the phloem part close to the secondary cambium. The highest concentration of carotenes is seen in the immediate vicinity to polyacetylene conglomerates. 相似文献
65.
The thermal decomposition of [Ni(H2O)6](ClO4)2 and [Ni(D2O)6](ClO4)2 were studied by thermogravimetric analysis (TG) and simultaneous differential thermal analysis (SDTA) at a constant heating
rate. The gaseous products of the decomposition were on-line identified by a quadrupole mass spectrometer (QMS). In both cases
the process of decomposition starts at ca. 410 K and is connected with removal of water molecules in a stepwise way; at the
beginning the first water molecule is lost, then the second and at higher temperature the third one. The rest of the water
molecules are lost in the temperature region of ClO4− decomposition.
The energy of activation of the process was calculated in both cases. 相似文献
66.
For elimination of copper interference in anodic stripping determinations of zinc at mercury and bismuth film electrodes gallium ions are usually added to the supporting electrolyte. In the presented studies novel ex situ formed gallium film electrode was applied for this purpose. The proposed electrode is less toxic than mercury one while the detection limit for zinc was lower than for bismuth film electrode following the same deposition time. The calibration graph for deposition time of 60 s was linear from 5 × 10−8 to 2 × 10−6 mol L−1. The determinations of zinc were carried out from undeaerated solutions. The proposed procedure was applied to zinc determination in certified reference material and tap water sample. 相似文献
67.
Bryszewska MA Ambroziak W Rudzinski J Lewis DJ 《Analytical and bioanalytical chemistry》2005,382(5):1279-1287
In the present study, selenium-enriched plant biomass was investigated to evaluate the ability of rye seedlings to take up, and assimilate, inorganic selenium. Two different analytical approaches were used. Electrophoretic separation (SDS-PAGE) of proteins extracted from 75Se-labelled biomass was used to investigate the biotransformation of selenite into organic forms of the element. Ion-pair chromatography coupled with ICP-MS detection was chosen for the analysis of selenium species, enzymatically extracted from the plant biomass. The results of three enzymatic hydrolysis procedures and three sequential enzymatic extractions procedures are compared. The most effective single extraction was proteolysis (using protease type XIV), giving an overall extraction efficiency of 48%. However, for combinations of enzymes, the most effective was cellulase (Trichoderma viride) followed by sequential extraction of the solid pellet using protease type XIV, giving an extraction efficiency of 70%. The complementary data from the electrophoretic fractionation of proteins, and the HPLC separation of Se-species in the proteolytic digests, reveal the existence of large number of selenium-containing compounds in the rye seedling plant biomass. The results showed the complete biotransformation of inorganic selenium into organic forms during germination of the rye seedlings. HPLC-ICP-MS analysis of extracts from the plant biomass did not show the presence of selenate or selenite. At the time of this study, the lack of suitable organic-MS facilities meant that it was not possible to characterise them fully. However, the data does show that a combination of different enzymes, rather than just the commonly-used protease, should be considered when developing an extraction strategy for selenium in different food types to those already reported in the literature. 相似文献
68.
Korolczuk M Moroziewicz A Grabarczyk M Kutyła R 《Analytical and bioanalytical chemistry》2004,380(1):141-145
A sensitive procedure for determination of micro-traces of Co(II) by adsorptive stripping voltammetry is proposed. The procedure exploits the enhancement of the cobalt peak obtained by use of the system Co(II)–dimethylglyoxime–piperazine-1,4-bis(2-ethanesulfonic acid)–cetyltrimethylammonium bromide. Using the optimized conditions, a detection limit (based on the 3 criterion) for Co(II) of 1.2×10–11 mol L–1 (0.7 ng L–1) was achieved. The calibration plot for an accumulation time of 30 s was linear from 5×10–11 to 4×10–9 mol L–1. The procedure was validated by analysis of certified reference materials and natural water samples. 相似文献
69.
Numerical Algorithms - A radialbasis function (RBF)–differentialquadrature (DQ) method is applied for the numerical solution of elliptic boundary value problems (BVPs) in three-dimensional... 相似文献
70.
Malgorzata A. Kaczorowska Helen J. Cooper 《Journal of the American Society for Mass Spectrometry》2010,21(8):1398-1403
We report electron induced dissociation (EID) Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry of the
singly-charged cations [Fe3O(CH3COO)6]+3 and [Fe3O (HCOO)6+H2O]+. Trinuclear oxo-centered carboxylate-bridged iron complexes of this type are of interest due to their electronic and magnetic
properties, and because of their role as synthetic precursors of single molecule magnets. EID of these complexes is particularly
efficient and provides detailed information about the triangular core, and the nature and number of ligands. EID behavior
is in marked contrast to the collision induced dissociation (CID) of these species. Whereas EID allows virtually complete
structural characterization, the structural information provided by CID is very limited. The results suggest that EID is particularly
suitable for the structural analysis of singly-charged polynuclear metal complexes. 相似文献