全文获取类型
收费全文 | 116篇 |
免费 | 2篇 |
专业分类
化学 | 88篇 |
晶体学 | 2篇 |
数学 | 2篇 |
物理学 | 26篇 |
出版年
2022年 | 7篇 |
2021年 | 6篇 |
2020年 | 8篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 1篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 7篇 |
2012年 | 5篇 |
2011年 | 3篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 5篇 |
2007年 | 5篇 |
2006年 | 14篇 |
2005年 | 6篇 |
2004年 | 1篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1979年 | 1篇 |
排序方式: 共有118条查询结果,搜索用时 0 毫秒
51.
Luiz Gustavo Lacerda Tiago André Denck Colman Tabata Bauab Marco Aurélio da Silva Carvalho Filho Ivo Mottin Demiate Eliane Carvalho de Vasconcelos Egon Schnitzler 《Journal of Thermal Analysis and Calorimetry》2014,115(2):1893-1899
The avocado (Persea americana, Miller) is a tree that is native to Central/North America (Mexico) and it is very popular worldwide due to its food applications. Its seeds contain an important amount of starch and there is lack of study and understanding regarding the physico-chemical properties of this biopolymer. In this research, starch granules were extracted from avocado seeds and oxidised with standard sodium hypochlorite solutions at 0.5, 1.0 and 2.0 %. Untreated and modified samples were investigated using the following techniques: simultaneous thermogravimetry–differential thermal analysis, differential scanning calorimetry, non-contact atomic force microscopy, rapid viscoamylographic analysis and X-ray powder patterns diffractometry. The main purpose was to investigate the thermal, structural and rheological behaviour of native and oxidised avocado starch, and it was verified that the treated samples showed a decrease in gelatinisation enthalpy and average roughness as well as in the degree of relative crystallinity and pasting properties. 相似文献
52.
53.
M. F. S. Rezende A. M. Lacerda H. -D. Pfannes R. A. Mansur J. D. Ardisson A. I. C. Persiano 《Hyperfine Interactions》1994,83(1):231-234
The effects of filing FeCoV alloys with equiatomic FeCo and up to 14 at% V is studied by Mössbauer spectroscopy and X-ray diffraction. We observed that filing eliminates the paramagnetic component observed in samples in the form of plates. The filed material also presents a linear increase of the lattice parameter and a linear decrease of the average hyperfine field of the alpha phase due to extra low-field satellites with increasing vanadium contents. This indicates that filing produces a gamma to alpha phase transformation, which increases the amount of vanadium in solid solution in the FeCo alpha phase. 相似文献
54.
Martins VL de Almeida LF de Castro SL Galvão RK de Araújo MC da Silva EC 《Journal of chemical information and computer sciences》2003,43(6):1725-1732
Instrumental analysis techniques that employ measurements based on inflection points may have their accuracy compromised due to the need for signal differentiation, which is very sensitive to instrumental noise. This paper presents a strategy for localizing inflection points that exploits the multiscale processing capability of the Wavelet Transform and avoids the need for explicit signal differentiation. The strategy is illustrated in simulated examples and also in a real analytical problem involving the determination of Pb and Cd by potentiometric stripping analysis. In this application, the results were in good agreement with the expected values and were slightly better than those obtained from the first derivative of the curves after smoothing by a Windowed Fourier Transform. 相似文献
55.
56.
Prachi Gupta Caroline Lacerda Vinod S. Patil Dipti Biswal Paritosh Wattamwar J. Zach Hilt Thomas D. Dziubla 《Journal of polymer science. Part A, Polymer chemistry》2017,55(12):2019-2026
Poly(β amino ester) (PβAE) polymers have received growing attention in the literature, owing to their ease of synthesis, versatile co‐monomer selection, and highly tunable degradation kinetics. As such, they have shown extensive potential in many biomedical applications as well. In this work, it is demonstrated for the first time that PβAE polymers containing primary and secondary amine groups can undergo degradation by primary alcohols via transesterification mechanism. While this work emphasizes an important aspect of solvent compatibility of these networks, it also represents an interesting, simple mechanism for post synthesis drug incorporation, with riboflavin conjugation being demonstrated as a model compound. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2019–2026 相似文献
57.
Detailed assignments of (1)H and (13)C NMR spectral data for 13 beta-substituted cycloenones are reported. The assignments are based on 1D (1)H and (13)C NMR and on 2D shift-correlated ((1)H,(13)C-HMQC and HMBC), J-resolved and COSY and double irradiation experiments. 相似文献
58.
Marzena Jankowska Teobald Kupka Leszek Stobiński Rasmus Faber Evanildo G. Lacerda Jr. Stephan P. A. Sauer 《Journal of computational chemistry》2016,37(4):395-403
Hartree–Fock and density functional theory with the hybrid B3LYP and general gradient KT2 exchange‐correlation functionals were used for nonrelativistic and relativistic nuclear magnetic shielding calculations of helium, neon, argon, krypton, and xenon dimers and free atoms. Relativistic corrections were calculated with the scalar and spin‐orbit zeroth‐order regular approximation Hamiltonian in combination with the large Slater‐type basis set QZ4P as well as with the four‐component Dirac–Coulomb Hamiltonian using Dyall's acv4z basis sets. The relativistic corrections to the nuclear magnetic shieldings and chemical shifts are combined with nonrelativistic coupled cluster singles and doubles with noniterative triple excitations [CCSD(T)] calculations using the very large polarization‐consistent basis sets aug‐pcSseg‐4 for He, Ne and Ar, aug‐pcSseg‐3 for Kr, and the AQZP basis set for Xe. For the dimers also, zero‐point vibrational (ZPV) corrections are obtained at the CCSD(T) level with the same basis sets were added. Best estimates of the dimer chemical shifts are generated from these nuclear magnetic shieldings and the relative importance of electron correlation, ZPV, and relativistic corrections for the shieldings and chemical shifts is analyzed. © 2015 Wiley Periodicals, Inc. 相似文献
59.
Emmanoel V. Silva-Filho Silvia M. Sella Eduardo C. Spinola Isaac R. Santos Wilson Machado Luiz D. Lacerda 《Microchemical Journal》2006,82(2):196-200
This work evaluates Hg, Zn, Fe and Mn transfer from the leachate of a refuse tip based on their accumulation in a sediment core of 17 cm collected in a leachate pond of a small refuse tip ageing approximately 10 years. Sediment samples were digested with an acid mixture (50% acqua regia solution), heated at 70 °C during 1 h, in a thermal-kinetic reactor “cold finger”. The extract was analysed to obtain Hg content by cold vapour absorption atomic spectrometry (CVAAS). Fe, Mn and Zn contents were obtained by flame atomic absorption spectrometry (FAAS) after total decomposition of the samples. Concentration ranges along the core varied from 0.16 to 0.58 μg g− 1; 7.3 to 145 μg g− 1; 11.7 to 116 μg g− 1 and 0.21% to 1.82% for Hg, Zn, Mn and Fe, respectively. All metals showed enrichment in the upper layers (above 6 cm) which probably correspond to the year 1996. Results indicated that Hg transfer is one order of magnitude higher than Zn and suggest that metals accumulation in sediments probably reduce their migration to groundwater. 相似文献
60.
Hong JS Vreeland WN Lacerda SH Locascio LE Gaitan M Raghavan SR 《Langmuir : the ACS journal of surfaces and colloids》2008,24(8):4092-4096
Nanosized gel particles (nanogels) are of interest for a variety of applications, including drug delivery and single-molecule encapsulation. Here, we employ the cores of nanoscale liposomes as reaction vessels to template the assembly of calcium alginate nanogels. For our experiments, a liposome formulation with a high bilayer melting temperature (Tm) is selected, and sodium alginate is encapsulated in the liposomal core. The liposomes are then placed in an aqueous buffer containing calcium chloride, and the temperature is raised up to Tm. This allows permeation of Ca2+ ions through the bilayer and into the core, whereupon these ions gel the encapsulated alginate. Subsequently, the lipid bilayer covering the gelled core is removed by the addition of a detergent. The resulting alginate nanogels have a size distribution consistent with that of the template liposomes (ca. 120-200 nm), as confirmed by transmission electron microscopy and light scattering. Nanogels of different average sizes can be synthesized by varying the template dimensions, and the gel size can be further tuned after synthesis by the addition of monovalent salt to the solution. 相似文献