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排序方式: 共有347条查询结果,搜索用时 15 毫秒
271.
Harna Patel Erik Nunes Gomes Bo Yuan Weiting Lyu Qingli Wu James E. Simon 《Molecules (Basel, Switzerland)》2022,27(20)
Catnip (Nepeta cataria L.) is of scientific interest largely due to the production of nepetalactones, volatile iridoid terpenes with strong arthropod repellent activity. However, the plant can also produce other bioactive volatile iridoids, such as nepetalic acid (NA), nepetalactam (NT) and dihydronepetalactone (DHNL) that have not been studied extensively. Germplasm studies on plants that can produce such compounds are scarce. The present study evaluated the chemical diversity of catnip genotypes with a focus on NA, NT and DHNL. A total of 34 genotypes were harvested at different times over two years. The ethanolic extract of the plants was screened for iridoids by ultra-high-performance liquid chromatography/triple quadrupole mass spectrometry. CR9 × CR3 genotype had the highest value for biomass yield, while cultivar CR9 had the highest value for accumulated NA. Genotype UK.2 had the highest value for accumulated NT yield and CR5 had the highest value for accumulated DHNL. Overall, patented cultivars and elite selections performed better than other less studied genotypes. Harvest time influenced the accumulation of secondary metabolites differentially for the genotypes. This is the first germplasm study with a focus on these iridoid compounds, yet more studies are necessary as genotype characterization is essential for breeding and standardization of products for industry. 相似文献
272.
Kaoping Song Jianwen Tao Xiuqin Lyu Yang Xu Shaopeng Liu Zhengbo Wang Huifeng Liu Yuxuan Zhang Hongtao Fu En Meng Mingxi Liu Hu Guo 《Molecules (Basel, Switzerland)》2022,27(20)
Polymer flooding is drawing lots of attention because of the technical maturity in some reservoirs. The first commercial polymer flooding in China was performed in the Daqing oilfield and is one of the largest applications in the world. Some laboratory tests from Daqing researchers in China showed that the viscoelasticity of high molecular weight polymers plays a significant role in increasing displacement efficiency. Hence, encouraged by the conventional field applications and new findings on the viscoelasticity effect of polymers on residual oil saturation (ROS), some high-concentration high-molecular-weight (HCHMW) polymer-flooding field tests have been conducted. Although some field tests were well-documented, subsequent progress was seldom reported. It was recently reported that HCHMW has a limited application in Daqing, which does not agree with observations from laboratory core flooding and early field tests. However, the cause of this discrepancy is unclear. Thus, a systematic summary of polymer-flooding mechanisms and field tests in China is necessary. This paper explained why HCHMW is not widely used when considering new understandings of polymer-flooding mechanisms. Different opinions on the viscoelasticity effect of polymers on ROS reduction were critically reviewed. Other mechanisms of polymer flooding, such as wettability change and gravity stability effect, were discussed with regard to widely reported laboratory tests, which were explained in terms of the viscoelasticity effects of polymers on ROS. Recent findings from Chinese field tests were also summarized. Salt-resistance polymers (SRPs) with good economic performance using produced water to prepare polymer solutions were very economically and environmentally promising. Notable progress in SRP flooding and new amphiphilic polymer field tests in China were summarized, and lessons learned were given. Formation blockage, represented by high injection pressure and produced productivity ability, was reported in several oil fields due to misunderstanding of polymers’ injectivity. Although the influence of viscoelastic polymers on reservoir conditions is unknown, the injection of very viscous polymers to displace medium-to-high viscosity oils is not recommended. This is especially important for old wells that could cause damage. This paper clarified misleading notions on polymer-flooding implementations based on theory and practices in China. 相似文献
273.
Mingliang Ma Yuying Yang Dili Liao Ping Lyu Jinwei Zhang Jianli Liang Lizhi Zhang 《应用有机金属化学》2019,33(2)
A strategy has been developed for the synthesis, characterization and catalysis of magnetic Fe3O4/P(GMA‐EGDMA)‐NH2/HPG‐COOH‐Pd core‐shell structure supported catalyst. The P(GMA‐EGDMA) polymer layer was coated on the surface of hollow magnetic Fe3O4 microspheres through the effect of KH570. The core‐shell magnetic Fe3O4/P(GMA‐EGDMA) modified by ‐NH2 could be grafted with HPG. Then, the hyperbranched glycidyl (HPG) with terminal ‐OH were modified by ‐COOH and adsorbed Pd nanoparticles. The hyperbranched polymer layer not only protected the Fe3O4 magnetic core from acid–base substrate corrosion, but also provided a number of functional groups as binding sites for Pd nanoparticles. The prepared catalyst was characterized by UV–vis, TEM, SEM, FTIR, TGA, ICP‐OES, BET, XRD, DLS and VSM. The catalytic tests showed that the magnetic Fe3O4/P(GMA‐EGDMA)‐NH2/HPG‐COOH‐Pd catalyst had excellent catalytic performance and retained 86% catalytic efficiency after 8 consecutive cycles. 相似文献
274.
Wang Teng Lyu Chun-yi Jiang Yue-hua Dong Xue-yan Wang Yan Li Zong-hong Wang Jin-xin Xu Rui-rong 《Molecular diversity》2021,25(4):2351-2365
Molecular Diversity - A poor prognosis, relapse and resistance are burning issues during adverse-risk acute myeloid leukaemia (AML) treatment. As a natural medicine, Scutellaria barbata D. Don... 相似文献
275.
Wang Shifeng Wang Zhiwei Lyu Jiahang Zhou Yuan Meng Jin Hu Long 《Journal of Russian Laser Research》2022,43(2):258-265
Journal of Russian Laser Research - Multilayer-lidar-used solution is popular though financial consumption is extremely expensive. In addition, multilayer lidars are barely able to reconstruct an... 相似文献
276.
277.
Benjamin P. Williams Allison P. Young Ilektra Andoni Yong Han Wei‐Shang Lo Matthew Golden Jane Yang Lian‐Ming Lyu Chun‐Hong Kuo James W. Evans Wenyu Huang Chia‐Kuang Tsung 《Angewandte Chemie (International ed. in English)》2020,59(26):10574-10580
Controlling the surface composition of shaped bimetallic nanoparticles could offer precise tunability of geometric and electronic surface structure for new nanocatalysts. To achieve this goal, a platform for studying the intermixing process in a shaped nanoparticle was designed, using multilayered Pd‐Ni‐Pt core–shell nanocubes as precursors. Under mild conditions, the intermixing between Ni and Pt could be tuned by changing layer thickness and number, triggering intermixing while preserving nanoparticle shape. Intermixing of the two metals is monitored using transmission electron microscopy. The surface structure evolution is characterized using electrochemical methanol oxidation. DFT calculations suggest that the low‐temperature mixing is enhanced by shorter diffusion lengths and strain introduced by the layered structure. The platform and insights presented are an advance toward the realization of shape‐controlled multimetallic nanoparticles tailored to each potential application. 相似文献
278.
Ryk modulates the niche activity of mesenchymal stromal cells by fine-tuning canonical Wnt signaling
Seon-Yeong Jeong Jungmook Lyu Jin-A Kim Il-Hoan Oh 《Experimental & molecular medicine》2020,52(7):1140
The importance of modulating the intensity of Wnt signaling has been highlighted in various biological models, but their mechanisms remain unclear. In this study, we found that Ryk—an atypical Wnt receptor with a pseudokinase domain—has a Wnt-modulating effect in bone marrow stromal cells to control hematopoiesis-supporting activities. We first found that Ryk is predominantly expressed in the mesenchymal stromal cells (MSCs) of the bone marrow (BM) compared with hematopoietic cells. Downregulation of Ryk in MSCs decreased their clonogenic activity and ability to support self-renewing expansion of primitive hematopoietic progenitors (HPCs) in response to canonical Wnt ligands. In contrast, under high concentrations of Wnt, Ryk exerted suppressive effects on the transactivation of target genes and HPC-supporting effects in MSCs, thus fine-tuning the signaling intensity of Wnt in BM stromal cells. This ability of Ryk to modulate the HPC-supporting niche activity of MSCs was abrogated by induction of deletion mutants of Ryk lacking the intracellular domain or extracellular domain, indicating that the pseudokinase-containing intracellular domain mediates the Wnt-modulating effects in response to extracellular Wnt ligands. These findings indicate that the ability of the BM microenvironment to respond to extracellular signals and support hematopoiesis may be fine-tuned by Ryk via modulation of Wnt signaling intensity to coordinate hematopoietic activity.Subject terms: Mesenchymal stem cells, Mesenchymal stem cells, Haematopoietic stem cells 相似文献
279.
Dr. Jingfeng Huo Kangbao Zhong Yazhen Xue MyeeMay Lyu Dr. Yifan Ping Wenbai Ouyang Dr. Zhenxing Liu Prof. Yu Lan Prof. Jianbo Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(27):e202200191
We report herein a highly efficient palladium-catalyzed carbene insertion into strained Si−C bonds of benzosilacyclobutanes, which provides an efficient method to access α-chiral silanes. With a sterically hindered ligand, carbene insertion into the C(sp3)−Si bond of benzosilacyclobutanes occurred in excellent site- and enantioselectivity, while C(sp2)−Si bond insertion occurred selectively with less sterically hindered ligands. Reaction mechanism, in particular the roles of the chiral ligands in controlling the site-selectivity of the insertion reactions, are elucidated by using hybrid density functional theory. 相似文献
280.
Hydrogeochemical evolution and groundwater quality assessment in the Dake Lake Basin,Northwest China
Lyu Min Pang Zhonghe Huang Tianming Yin Lihe 《Journal of Radioanalytical and Nuclear Chemistry》2019,320(3):865-883
This study aims to study hydrochemical characteristics and evolution of groundwater, and to assess suitability for human drinking in Dake Lake Basin, Northwest China. Hierarchical cluster analysis produces two geochemically distinct clusters, C1 and C2, which are dominated by Ca·Mg–HCO3 and Na–HCO3 type, respectively. C1 and C2 belong to shallow local and deep regional flow systems, respectively. Carbonate dissolution and ion exchange process dominate in C1 and C2, respectively. C1 groundwater is not suitable for human drinking due to relatively high NO3? contents caused by agricultural activities; while C2 groundwater is suitable for human consumption.
相似文献