全文获取类型
收费全文 | 154篇 |
免费 | 13篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 89篇 |
机械仪表 | 3篇 |
建筑科学 | 5篇 |
能源动力 | 6篇 |
轻工业 | 23篇 |
水利工程 | 2篇 |
石油天然气 | 4篇 |
无线电 | 5篇 |
一般工业技术 | 12篇 |
冶金工业 | 7篇 |
原子能技术 | 1篇 |
自动化技术 | 9篇 |
出版年
2023年 | 2篇 |
2022年 | 22篇 |
2021年 | 31篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 8篇 |
2016年 | 8篇 |
2015年 | 6篇 |
2014年 | 4篇 |
2013年 | 11篇 |
2012年 | 6篇 |
2011年 | 9篇 |
2010年 | 3篇 |
2009年 | 6篇 |
2008年 | 5篇 |
2007年 | 5篇 |
2005年 | 2篇 |
2004年 | 7篇 |
2003年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有167条查询结果,搜索用时 140 毫秒
151.
152.
153.
Paweł Wajer Edyta Woźniak Wlodek Kofman Marcin Rybicki Stanisław Lewiński 《International journal of remote sensing》2018,39(9):2671-2689
This study uses the ray tracing method to simulate synthetic aperture radar (SAR) images of urban areas. The images are constructed for polarisations: horizontal-horizontal (HH) and vertical-vertical (VV), and different types of buildings, vegetation, and streets. Simulated images of a given area are compared with real SAR images of the same area acquired by the TerraSAR-X satellite. The simulations use the measured backscatter coefficient for HH and VV polarisations and for five different classes of terrain: houses, trees, shrubs, grass, and ground. For multiple reflections, we apply the generalized bistatic Lambertian model. The results show that, despite the limits of the ray tracing method and the approximations involved in modelling three-dimensional objects in the simulated scene, the simulated SAR images correspond well with the actual scene. All features present in the real image are reproduced in the simulated image; in particular, the double reflections of buildings and the surrounding ground appear clearly. However, discrepancies exist, and these are also discussed. 相似文献
154.
Activated carbons modified with different chemical agents such as HNO3, H2SO4, peroxyacetic acid (PAA), air, NH3 and Cl2 have been tested as catalysts in decomposition (dehydration and dehydrogenation) of isopropanol. The majority of the samples obtained have been characterised by well-developed microporous surface with a small contribution of mesopores (8–18%). The influence of the surface area of the samples on their catalytic performance has been insignificant. The carbon oxidation with oxidants in the liquid or gas phase leads to an increased catalytic activity and the dominant process is dehydration of the alcohol studied. Carbon modification by contact with gas ammonia or chlorine results in a decrease in the catalytic activity and a significant increase in the contribution of dehydrogenation of isopropanol. It has been shown that such behaviour of the catalysts has been a consequence of changes in the acid-base character of the carbons induced by their modification. 相似文献
155.
156.
Anna Drzazga Daria Kamiska Anna Gliszczyska Edyta Gendaszewska-Darmach 《International journal of molecular sciences》2021,22(11)
Insulin plays a significant role in carbohydrate homeostasis as the blood glucose lowering hormone. Glucose-induced insulin secretion (GSIS) is augmented by glucagon-like peptide (GLP-1), a gastrointestinal peptide released in response to ingesting nutriments. The secretion of insulin and GLP-1 is mediated by the binding of nutrients to G protein-coupled receptors (GPCRs) expressed by pancreatic β-cells and enteroendocrine cells, respectively. Therefore, insulin secretagogues and incretin mimetics currently serve as antidiabetic treatments. This study demonstrates the potency of synthetic isoprenoid derivatives of lysophosphatidylcholines (LPCs) to stimulate GSIS and GLP-1 release. Murine insulinoma cell line (MIN6) and enteroendocrinal L cells (GLUTag) were incubated with LPCs bearing geranic acid (1-GA-LPC), citronellic acid (1-CA-LPC), 3,7-dimethyl-3-vinyloct-6-enoic acid (GERA-LPC), and (E)-3,7,11-trimethyl- 3-vinyldodeca-6,10-dienoic acid (1-FARA-LPC). Respective free terpene acids were also tested for comparison. Besides their insulin- and GLP-1-secreting capabilities, we also investigated the cytotoxicity of tested compounds, the ability to intracellular calcium ion mobilization, and targeted GPCRs involved in maintaining lipid and carbohydrate homeostasis. We observed the high cytotoxicity of 1-GERA-LPC and 1-FARA-LPC in contrast 1-CA-LPC and 1-GA-LPC. Moreover, 1-CA-LPC and 1-GA-LPC demonstrated the stimulatory effect on GSIS and 1-CA-LPC augmented GLP-1 secretion. Insulin and GLP-1 release appeared to be GPR40-, GPR55-, GPR119- and GPR120-dependent. 相似文献
157.
158.
Magdalena Hasik Wincenty Turek Anna Nyczyk Edyta Stochmal Andrzej Bernasik Agnieszka Sniechota Agnieszka Sołtysek 《Catalysis Letters》2009,127(3-4):304-311
Composites of polyaniline (PANI) or polypyrrole (PPy) doped with chloride ions and Pt or Rh particles were prepared by chemical reduction of metal ions conducted in the presence of the polymers. Based on X-ray diffraction studies it was established that the composites contained metal nanoparticles (5–9 in size). However, according to SEM investigations metal particles were agglomerated (40 nm–1.1 μm in size). Redox activity of the composites in the catalytic isopropyl alcohol conversion was ca. ten times higher than the acid–base one. Pt dispersed in polymer matrices showed higher catalytic activity than Rh. PPy doped with chloride ions had a promoting effect on the activity of Pt catalysts. 相似文献
159.
The use of new resonance integrals for determining the parameters of the epithermal neutron spectrum
A. M. Khil’manovich T. N. Korbut S. V. Korneev B. A. Martsynkevich A. Yu. Fokov 《Instruments and Experimental Techniques》2009,52(3):333-336
A simple method for determining parameters α and b in the presentation of the epithermal neutron spectrum in the form of φepi(E) = b/E 1 + α using expansion of function φepi(E) in Taylor series with respect to parameter α is described. The problem of determining the parameters is reduced to finding a solution to a system of algebraic equations. The approximation used describes the spectrum with an adequate accuracy up to energies of ~1–50 keV, depending on value α ~ 0.2?0.1, with the help of the first two or three expansion terms (resonance integrals), respectively. The first two resonance integrals for reactions 197Au(n, γ)198Au and 55Mn(n, γ)56Mn are estimated. The measured rates of the appropriate reactions and the values of parameters α and b for the case of an assembly with a graphite moderator are presented. 相似文献
160.
Agnieszka Krawczyk-ebek Monika Dymarska Tomasz Janeczko Edyta Kostrzewa-Susow 《International journal of molecular sciences》2021,22(17)
Flavonoids, including chalcones, are more stable and bioavailable in the form of glycosylated and methylated derivatives. The combined chemical and biotechnological methods can be applied to obtain such compounds. In the present study, 2′-hydroxy-2-methylchalcone was synthesized and biotransformed in the cultures of entomopathogenic filamentous fungi Beauveria bassiana KCH J1.5, Isaria fumosorosea KCH J2 and Isaria farinosa KCH J2.6, which have been known for their extensive enzymatic system and ability to perform glycosylation of flavonoids. As a result, five new glycosylated dihydrochalcones were obtained. Biotransformation of 2′-hydroxy-2-methylchalcone by B. bassiana KCH J1.5 resulted in four glycosylated dihydrochalcones: 2′-hydroxy-2-methyldihydrochalcone 3′-O-β-d-(4″-O-methyl)-glucopyranoside, 2′,3-dihydroxy-2-methyldihydrochalcone 3′-O-β-d-(4″-O-methyl)-glucopyranoside, 2′-hydroxy-2-hydroxymethyldihydrochalcone 3′-O-β-d-(4″-O-methyl)-glucopyranoside, and 2′,4-dihydroxy-2-methyldihydrochalcone 3′-O-β-d-(4″-O-methyl)-glucopyranoside. In the culture of I. fumosorosea KCH J2 only one product was formed—3-hydroxy-2-methyldihydrochalcone 2′-O-β-d-(4″-O-methyl)-glucopyranoside. Biotransformation performed by I. farinosa KCH J2.6 resulted in the formation of two products: 2′-hydroxy-2-methyldihydrochalcone 3′-O-β-d-(4″-O-methyl)-glucopyranoside and 2′,3-dihydroxy-2-methyldihydrochalcone 3′-O-β-d-(4″-O-methyl)-glucopyranoside. The structures of all obtained products were established based on the NMR spectroscopy. All products mentioned above may be used in further studies as potentially bioactive compounds with improved stability and bioavailability. These compounds can be considered as flavor enhancers and potential sweeteners. 相似文献