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81.
Marcelo Donadel Malesuik Simone Gonçalves Cardoso Martin Steppe 《Chromatographia》2008,67(1-2):131-136
A reversed-phase liquid chromatographic (LC) method was developed for the assay of nitazoxanide (NTZ) in solid dosage formulations.
An isocratic LC separation was performed on a Phenomenex Synergi Fusion C18 column (250 mm × 4.6 mm, i.d., 4 μm particle size) using a mobile phase of 0.1% o-phosphoric acid solution, pH 6.0: acetonitrile (45:55, v/v) at a flow rate of 1.0 mL min−1. Detection was achieved with a photodiode array detector at 240 nm. The detector response for NTZ was linear over the concentration
range from 2 to 100 μg mL−1 (r = 0.9999). The specificity and stability-indicating capability of the method were proved using stress conditions. The RSD
values for intra-day precision were less than 1.0% for tablets and powder for oral suspension. The RSD values for inter-day
precision were 0.6 and 0.7% for tablets and powder for oral suspension. The accuracy was 100.4% (RSD = 1.8%) for tablets and
100.9% (RSD = 0.3%) for powder for oral suspension. The limits of quantitation and detection were 0.4 and 0.1 μg mL−1. There was no interference of the excipients on the determination of the active pharmaceutical ingredient. The proposed method
was precise, accurate, specific, and sensitive. It can be applied to the quantitative determination of drug in tablets and
powder for oral suspension. 相似文献
82.
J. C. Maciel A. A. D. Mercês M. Cabrera W. T. Shigeyosi S. D. de Souza M. Olzon-Dionysio J. D. Fabris C. A. Cardoso D. F. M. Neri M. P. C. Silva L. B. CarvalhoJr. 《Hyperfine Interactions》2016,237(1):3
It is reported the synthesis of magnetic nanoparticles via the chemical co-precipitation of Fe 3+ ions and their preparation by coating them with polyaniline. The electronic micrograph analysis showed that the mean diameter for the nanoparticles is ~15 nm. FTIR, powder X-ray diffraction and Mössbauer spectroscopy were used to understand the chemical, crystallographic and 57Fe hyperfine structures for the two samples. The nanoparticles, which exhibited magnetic behavior with relatively high spontaneous magnetization at room temperature, were identified as being mainly formed by maghemite (γFe2O3). The coated magnetic nanoparticles (sample labeled “mPANI”) presented a real ability to bind biological molecules such as trypsin, forming the magnetic enzyme derivative (sample “mPANIG-Trypsin”). The amount of protein and specific activity of the immobilized trypsin were found to be 13±5 μg of protein/mg of mPANI (49.3 % of immobilized protein) and 24.1±0.7 U/mg of immobilized protein, respectively. After 48 days of storage at 4 °C, the activity of the immobilized trypsin was found to be 89 % of its initial activity. This simple, fast and low-cost procedure was revealed to be a promising way to prepare mPANI nanoparticles if technological applications addressed to covalently link biomolecules are envisaged. This route yields chemically stable derivatives, which can be easily recovered from the reaction mixture with a magnetic field and recyclable reused. 相似文献
83.
Steffany Manzan Marques de Souza Pedro Ivo Brandão e Melo Franco Maria Inês Gonçalves Leles Edemilson Cardoso da Conceição 《Journal of Thermal Analysis and Calorimetry》2016,123(3):1943-1949
Differential scanning calorimetry (DSC) and thermogravimetry (TG) were used in order to evaluate the thermal stability of an enalapril maleate formulation packaged in two types of packaging, polyvinyl chloride/aluminum blister and aluminum strip. Enalapril and the excipients employed in the formulation were also evaluated by TG and DSC. Tablets were analyzed before and after storage in an acclimatized room at 40 °C and relative humidity of 75 % for 90 days. The DSC and TG results were compared with the results of dosage of enalapril and related compounds obtained by high-performance liquid chromatography. These results indicate an occurrence of chemical interaction between enalapril maleate and the excipients during its storage. After storage, it was observed that the enalapril content reduced and the predominant degradation product was diketopiperazine for both types of packaging. The predominance of diketopiperazine could be related to the absence of sodium bicarbonate in the tablets, alkalinizing agent employed in the thermal stabilization of the drug. 相似文献
84.
Agibert SA Moreira MB Ratusznei SM Rodrigues JA Zaiat M Foresti E 《Applied biochemistry and biotechnology》2007,136(2):193-206
The effect of temperature on the performance of an anaerobic sequencing biofilm batch reactor (ASBBR) with liquid-phase recirculation
was assessed. Assays were performed using a recirculation velocity of 0.20 cm/s, 8-h cycles, and an average treated synthetic
wastewater volume of 2 L/cycle with a concentration of 500 mg of Chemical Oxygen Demand (COD)/L. Operation temperatures were
15, 20, 25, 30, and 35°C. At 25, 30, and 35°C, organic matter removal efficiencies for filtered samples ranged from 81 to
83%. At lower temperatures, namely 15 and 20°C, removal efficiency decreased significantly to 61 and 65%, respectively. A
first-order model could be fitted to the experimental concentration profile values. The first-order kinetic parameter value
of this model varied from 0.46 to 0.81 h1 considering the lowest and highest temperature studied. Moreover, analysis of the removal profile values allowed fitting
of an Arrhenius-type equation with an activation energy of 5715 cal/mol. 相似文献
85.
de Almeida MV Teixeira FM de Souza MV Amarante GW Alves CC Cardoso SH Mattos AM Ferreira AP Teixeira HC 《Chemical & pharmaceutical bulletin》2007,55(2):223-226
Fourteen thalidomide analogs bearing two phthalimido units were prepared in high yields (83-94%) by condensation of different diamines with phthalic or 3-nitrophthalic anhydride. An in vitro investigation of the compounds as inhibitors of the TNF-alpha production was performed. The inhibition was higher for compounds bearing amino and nitro groups and was modulated by increasing the size of the spacers between the phthalimide groups. 相似文献
86.
Gabriela Vargas‐Pineda Marcela Lpez‐Cardoso Patricia García y García Raymundo Cea‐Olivares 《Heteroatom Chemistry》2004,15(6):451-453
12‐Chloro‐12‐n‐butyl‐1,11‐dioxa‐4,8‐ dithia‐12‐stannacyclododecane ( 3a ) and 12‐chloro‐ 12‐n‐butyl‐1,4,8,11‐tetrathia‐12‐stannacyclododecane ( 3b ) have been prepared by reacting n‐butyltin trichloride with 1,11‐dioxa‐4,8‐dithiaundecane and 1,4,8,11‐tetrathiaundecane, respectively. Complexes 3a,b were characterized by elemental analyses, IR, electron impact mass spectrometry, and multinuclear NMR (1H, 13C, and 119Sn). The spectroscopic data are consistent with bonding of the ligands through both sulfur and oxygen atoms in 3a and through all sulfur atoms in 3b to the Sn(IV) center. We suggest hexacoordination around the Sn atoms. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:451–453, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20040 相似文献
87.
J. Cardoso R. Manrique M. Albores-Velasco A. Huanosta 《Journal of Polymer Science.Polymer Physics》1997,35(3):479-488
The synthesis, characterization, thermal, and dielectric properties of three different zwitterionic methacrylates of the sulfobetaine type are presented. Diethylamine-ethyl-, 2-(diethylaminoethoxy)-ethyl-, and 2-(2-diethylaminoethoxy) ethoxy-ethyl-methacrylates were made to react with butanosultone to prepare monomers with variable flexibility. The flexibility of the lateral chain of the polymethacrylates decreased the glass transition temperature (Tg down to 300 K) of the polymers. A linear relationship between Tg and the number of carbon atoms was shown for these materials. X-ray diffraction and DSC experiments showed the formation of new ordered phases in these polymers, which inhibited their dipole conductivity. On heating, these phases were destroyed and values of conductivity of 10−7–10−3 S cm−1 were obtained in the studied range of temperature. Variation of conductivity with temperature was established according to the Arrhenius equation. Dielectric properties exhibited a small deviation of the Debye type behavior, and β parameters of the Cole–Cole equations were calculated for the synthesized polymers. © 1997 John Wiley & Sons, Inc. 相似文献
88.
Yesenia Mendoza García Ana Luiza Coeli Cruz Ramos Afonso Henrique de Oliveira Júnior Ana Cardoso Clemente Filha Ferreira de Paula Angelita Cristine de Melo Moacir Alves Andrino Mauro Ramalho Silva Rodinei Augusti Raquel Linhares Bello de Araújo Eurico Eduardo Pinto de Lemos Júlio Onsio Ferreira Melo 《Molecules (Basel, Switzerland)》2021,26(23)
Myrciaria floribunda, also known as rumberry, is a tree native to the Brazilian Atlantic Forest, where its fruits have the potential for commercial use. This study evaluates the antioxidant potential, determines the phytochemical profile, and chemically characterizes the rumberry fruit. Accessions were sampled from the Rumberry Active Germplasm Bank of the Federal University of Alagoas, Brazil. Physical characteristics, chemical characteristics, and phenolic compound content were analyzed. Chemical profile characterization was carried out using PSMS. Accessions had an average weight of 0.86 g. Accession AC137 presented a higher pulp yield (1.12 g). AC132 and AC156 had larger fruits, AC137 showed greater firmness (5.93 N), and AC160 had a higher and total phenolic content ratio (279.01 ± 11.11). Orange-colored accessions scored higher in evaluated parameters, except for AC160 for phenolic content. Thirty-two compounds were identified on positive ionization mode and 42 compounds on negative ionization mode using PSMS. Flavonoids, followed by the derivatives of benzoic acid, sugars, and phenylpropanoids, were the most prominent. Myricitrin, quercitrin, and catechin stand out as flavonoids that have been reported in previous studies with antioxidant and antimicrobial properties, in addition to health and therapeutical benefits, demonstrating the potential of the rumberry fruit. 相似文献
89.
Juan Carlos Sandoval‐Santana Victor Guadalupe Ibarra‐Sierra Jos Luis Cardoso Alejandro Kunold Pedro Roman‐Taboada Gerardo Naumis 《Annalen der Physik》2019,531(8)
Time‐driven quantum systems are important in many different fields of physics as cold atoms, solid state, optics, etc. Many of their properties are encoded in the time evolution operator or the effective Hamiltonian. Finding these operators usually requires very complex calculations that often involve some approximations. To perform this task, a systematic scheme that can be cast in the form of a symbolic computational algorithm is presented. It is suitable for periodic and non‐periodic potentials and, for convoluted systems, can also be adapted to yield numerical solutions. The method exploits the structure of the associated Lie group and a decomposition of the evolution operator on each group generator. To illustrate the use of the method, five examples are provided: harmonic oscillator with time‐dependent frequency (Paul trap), modulated optical lattice, time‐driven quantum oscillator, a step‐wise driving of a free particle, and the non‐periodic Caldirola‐Kanai Hamiltonian. To the extent of the authors' knowledge, whereas the exact form of Paul trap's evolution operator is well known, its effective Hamiltonian was until now unknown. The remaining four examples accurately reproduce previous results. 相似文献
90.
The multiquark confining potential is proportional to the total distance of the fundamental strings linking the quarks and antiquarks. We address the computation of the total string distance and of the Fermat points where the different strings meet. For a meson the distance is trivially the quark–antiquark distance. For a baryon the problem was solved geometrically from the onset by Fermat and by Torricelli, it can be determined just with a rule and a compass, and we briefly review it. However we also show that for tetraquarks, pentaquarks, hexaquarks, etc., the geometrical solution is much more complicated. Here we provide an iterative method, converging fast to the correct Fermat points and the total distances, relevant for the multiquark potentials. 相似文献