全文获取类型
收费全文 | 83篇 |
免费 | 4篇 |
专业分类
化学 | 43篇 |
力学 | 1篇 |
数学 | 29篇 |
物理学 | 14篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2021年 | 1篇 |
2020年 | 7篇 |
2019年 | 2篇 |
2017年 | 1篇 |
2016年 | 8篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 10篇 |
2012年 | 6篇 |
2011年 | 5篇 |
2010年 | 3篇 |
2009年 | 5篇 |
2008年 | 5篇 |
2007年 | 5篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 2篇 |
1989年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有87条查询结果,搜索用时 31 毫秒
71.
Cagdas Okutucu Gozde Duman Suat Ucar Ihsan Yasa Jale Yanik 《Journal of Analytical and Applied Pyrolysis》2011,91(1):140-146
The main objective of this study was to evaluate the feasibility of pistachio shell as a biomass feedstock for the production of fungicidal oil and a precursor for the production of activated carbon by physical activation. For this purpose, pistachio shell was pyrolyzed in a fixed bed reactor at the different temperatures (300-600 °C). The pyrolysis products were identified as gas, bio-oil, aqueous solution and char. The product distribution from pyrolysis process did not significantly change when the pyrolysis temperature was above 300 °C. The pyrolysis gas product had low calorific value since it contained the high proportion of carbon oxides. Because of their high oxygen content, the bio-oils were found not to be used as a fuel. Thus, the bio-oil was tested again four different types of fungi (pathogenetic, wood decaying and saprophyting). It was shown fungicidal activity again all tested fungi at the concentration of 10-50 mg ml−1. The pyrolysis char was evaluated as a precursor for the production of activated carbon. The surface area and micropore volume of the activated carbon produced from the char by CO2 activation at 900 °C were found to be 708 m2 g−1 and 0.280 cm3 g−1, respectively. 相似文献
72.
73.
74.
A new and simple high-performance liquid chromatography method was developed and validated for the simultaneous determination
of retinol, retinyl palmitate and β-carotene in rat serum treated with Hypericum Perforatum L. and 7,12-dimethylbenz[a]anthracene. Furthermore, vitamin C was determined spectrophotometrically. High-performance liquid chromatography analysis
was performed utilizing an Inertsil ODS3 reversed phase column with methanol-acetonitrile-tetrahydrofuran (65:30:5, v/v/v)
as mobile phase, at a flow rate of 1.5 mL min−1 and 40°C. Diode-array detection was conducted at 325 and 450 nm for retinol and retinyl palmitate, and β-carotene, respectively
with a running time of 26 min. The high-performance liquid chromatography assay and extraction procedure proposed are simple,
rapid, sensitive and accurate. This method was then applied to determine the amounts of retinol, retinyl palmitate and β-carotene
in rat serum. Results of this study demonstrated that at 60th day in the 7,12-dimethylbenz[a]anthracene-treated group there was a significant decrease (p<0.001), (p<0,01), (p<0.05) in levels of retinol, retinyl palmitate
and vitamin C, respectively compared to the control group levels. A significant decrease (p<0.01) in retinyl palimitate was
observed in the 7,12 dimethylbenz[a] anthracene + Hypericum Perforatum L. treated group compared to the control group.. 相似文献
75.
Polypropylene-based nanocomposites filled with polypropylene-grafted multiwalled carbon nanotubes (PP-g-MWNT) were compared to PP samples filled with pristine MWNT. The effect of such additives on the structure and morphology of the polymer matrix was studied by small angle X-ray scattering (SAXS), wide angle X-ray diffraction (WAXD), polarized light optical microscopy (PLOM) and differential scanning calorimetry (DSC). PP-g-MWNT allowed a more efficient and unhindered crystallization at a lamellar level, while MWNT disrupted the order of lamellar stacks, probably because of their tendency to aggregate. A common trend of tensile properties and lamellar morphology as a function of filler content was noted in the series filled with functionalized carbon nanotubes. 相似文献
76.
Feng L Geisselbrecht Y Blanck S Wilbuer A Atilla-Gokcumen GE Filippakopoulos P Kräling K Celik MA Harms K Maksimoska J Marmorstein R Frenking G Knapp S Essen LO Meggers E 《Journal of the American Chemical Society》2011,133(15):5976-5986
The generation of synthetic compounds with exclusive target specificity is an extraordinary challenge of molecular recognition and demands novel design strategies, in particular for large and homologous protein families such as protein kinases with more than 500 members. Simple organic molecules often do not reach the necessary sophistication to fulfill this task. Here, we present six carefully tailored, stable metal-containing compounds in which unique and defined molecular geometries with natural-product-like structural complexity are constructed around octahedral ruthenium(II) or iridium(III) metal centers. Each of the six reported metal compounds displays high selectivity for an individual protein kinase, namely GSK3α, PAK1, PIM1, DAPK1, MLCK, and FLT4. Although being conventional ATP-competitive inhibitors, the combination of the unusual globular shape and rigidity characteristics, of these compounds facilitates the design of highly selective protein kinase inhibitors. Unique structural features of the octahedral coordination geometry allow novel interactions with the glycine-rich loop, which contribute significantly to binding potencies and selectivities. The sensitive correlation between metal coordination sphere and inhibition properties suggests that in this design, the metal is located at a "hot spot" within the ATP binding pocket, not too close to the hinge region where globular space is unavailable, and at the same time not too far out toward the solvent where the octahedral coordination sphere would not have a significant impact on potency and selectivity. This study thus demonstrates that inert (stable) octahedral metal complexes are sophisticated structural scaffolds for the design of highly selective chemical probes. 相似文献
77.
Serhat Keser Fatma Keser Omer Kaygili Suat Tekin Ersin Demir Ismail Turkoglu 《Natural product research》2020,34(5):714-719
AbstractHypericum scabrum L. has been widely used in traditional medicine for the treatment of many diseases just as the other Hypericum species. In the present study, the antiradical, antimicrobial and cytotoxic activities of water and ethanol extracts of H. scabrum flowers were investigated. Their phytochemical contents and composition were also determined. The water and ethanol extracts are better scavenged ABTS (97.89 and 98.99%) and OH radicals (96.36 and 97.33%); the water extract is better scavenged DPPH radicals (91.66%) than the standard antioxidant BHA (94.33, 85.19, 90.16%, respectively). Flowers of H. scabrum contain flavonoids, phenolic acids, vitamins and phytosterols, dominated by catechin, vanillic acid, vitamin K and ergosterol. The extracts exhibit a strong cytotoxic activity against MCF-7, HCT-116, and LNCaP cancer cell lines. It is found that their antimicrobial activities are higher than the standard antibiotics. These results indicate that H. scabrum flowers have potent antiradical, antimicrobial and cytotoxic activities. 相似文献
78.
In this paper we present an efficient numerical algorithm for solving linear and nonlinear boundary value problems with two-point
boundary conditions of tenth-order. The differential transform method is applied to construct the numerical solutions. The
proposed algorithm avoids the complexity provided by other numerical approaches. Several illustrative examples are given to
demonstrate the effectiveness of the present algorithm.
相似文献
79.
Abdullah Ekin Dean C. Webster 《Journal of polymer science. Part A, Polymer chemistry》2006,44(16):4880-4894
Libraries of 3‐aminopropyl‐terminated poly(dimethylsiloxane) (APT–PDMS) and poly(?‐caprolactone)–poly(dimethylsiloxane)–poly(?‐caprolactone) (PCL—PDMS–PCL) triblock copolymers were synthesized. Preliminary experiments were carried out to select an appropriate catalyst and route for the poly(dimethylsiloxane) synthesis, and trial experiments were conducted to verify the successful synthesis of the intended polymer compositions. Then, a series of APT–PDMS oligomers were synthesized with an automated combinatorial high‐throughput synthesis system to cover a molecular weight range of 2500–50,000 g/mol. Trial PCL—PDMS–PCL triblock copolymers were synthesized with the automated reactor system and characterized in detail with rapid gel permeation chromatography, high‐throughput Fourier transform infrared, nuclear magnetic resonance, and differential scanning calorimetry. Finally, two library synthesis experiments were carried out in which the lengths of both the poly(dimethylsiloxane) and poly(?‐caprolactone) blocks in the PCL—PDMS–PCL triblock copolymers were varied. The results obtained from these experiments demonstrated that it was possible to synthesize libraries of well‐defined APT–PDMS oligomers and PCL—PDMS–PCL triblock copolymers with an automated high‐throughput system. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4880–4894, 2006 相似文献
80.
Preparation and characterization of activated carbon produced from pomegranate seeds by ZnCl2 activation 总被引:1,自引:0,他引:1
In this study, pomegranate seeds, a by-product of fruit juice industry, were used as precursor for the preparation of activated carbon by chemical activation with ZnCl2. The influence of process variables such as the carbonization temperature and the impregnation ratio on textural and chemical-surface properties of the activated carbons was studied. When using the 2.0 impregnation ratio at the carbonization temperature of 600 °C, the specific surface area of the resultant carbon is as high as 978.8 m2 g−1. The results showed that the surface area and total pore volume of the activated carbons at the lowest impregnation ratio and the carbonization temperature were achieved as high as 709.4 m2 g−1 and 0.329 cm3 g−1. The surface area was strongly influenced by the impregnation ratio of activation reagent and the subsequent carbonization temperature. 相似文献