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排序方式: 共有4529条查询结果,搜索用时 11 毫秒
61.
Kazuo Tsubota Stephen C. Pflugfelder Zuguo Liu Christophe Baudouin Hyo Myung Kim Elisabeth M. Messmer Friedrich Kruse Lingyi Liang Jimena Tatiana Carreno-Galeano Maurizio Rolando Norihiko Yokoi Shigeru Kinoshita Reza Dana 《International journal of molecular sciences》2020,21(23)
Over the past decades, the number of patients with dry eye disease (DED) has increased dramatically. The incidence of DED is higher in Asia than in Europe and North America, suggesting the involvement of cultural or racial factors in DED etiology. Although many definitions of DED have been used, discrepancies exist between the various definitions of dry eye disease (DED) used across the globe. This article presents a clinical consensus on the definition of DED, as formulated in four meetings with global DED experts. The proposed new definition is as follows: “Dry eye is a multifactorial disease characterized by a persistently unstable and/or deficient tear film (TF) causing discomfort and/or visual impairment, accompanied by variable degrees of ocular surface epitheliopathy, inflammation and neurosensory abnormalities.” The key criteria for the diagnosis of DED are unstable TF, inflammation, ocular discomfort and visual impairment. This definition also recommends the assessment of ocular surface epitheliopathy and neurosensory abnormalities in each patient with suspected DED. It is easily applicable in clinical practice and should help practitioners diagnose DED consistently. This consensus definition of DED should also help to guide research and clinical trials that, to date, have been hampered by the lack of an established surrogate endpoint. 相似文献
62.
减摩耐磨用无机颗粒/高分子复合材料研究的进展 总被引:8,自引:1,他引:8
综述了减摩抗磨用无机颗粒/高分子复合材料的最新研究进展,重点阐述了不同类型无机颗粒的作用机理及其对复合材料最终性能的影响,指出这类材料的发展趋势在于应用纳米填料,通过发展适当的分散技术,同时加强粒子与基体的结合,有可能克服现有微米颗粒复合材料中存在的缺点,全面提高复合材料的综合性能。 相似文献
63.
Enzo Mangano Daniel Friedrich Stefano Brandani 《American Institute of Chemical Engineers》2015,61(3):981-991
The ideal adsorbed solution (IAS) theory has been shown to predict reliably multicomponent adsorption for both gas and liquid systems. There is a lack of understanding of the conditions which guarantee convergence for various algorithms used to solve the IAS theory equations and inconsistencies are present in the reported computational effort required for the different approaches. The original nested loop and the FastIAS technique are revisited. The resulting system of equations is highly nonlinear but both methods are shown to be robust if appropriate choices are made for the starting values of the unknown variables. New initial conditions are proposed and the resulting algorithms are compared in a consistent manner with the main methods available to solve the IAS theory equations. The algorithms are extended for the first time to all nontype I isotherms. © 2014 American Institute of Chemical Engineers AIChE J, 61: 981–991, 2015 相似文献
64.
Jarau S Hrncir M Ayasse M Schulz C Francke W Zucchi R Barth FG 《Journal of chemical ecology》2004,30(4):793-804
By depositing scent marks on flowers, bees reduce both the search time and the time spent with the handling of nonrewarding flowers. They thereby improve the efficiency of foraging. Whereas in honey bees the source of these scent marks is unknown, it is assumed to be the tarsal glands in bumble bees. According to histological studies, however, the tarsal glands lack any openings to the outside. Foragers of the stingless bee Melipona seminigra have previously been shown to deposit an attractant pheromone at sugar solution feeders, which is secreted at the tips of their tarsi. Here we show that the claw retractor tendons have specialized glandular epithelia within the femur and tibia of all legs that produce this pheromone. The secretion accumulates within the hollow tendon, which also serves as the duct to the outside, and is released from an opening at the base of the unguitractor plate. In choice experiments, M. seminigra was attracted by feeders baited with pentane extracts of the claw retractor tendons in the same way as it was attracted by feeders previously scent marked by foragers. Our results resolve the seeming contradiction between the importance of foot print secretions and the lack of openings of the tarsal glands. 相似文献
65.
Chemical functionalization of carbon nanotubes (CNT) with nucleophiles requires introduction of electrophilic reactive sites on the CNTs. This can, for instance, be accomplished by the chemical bromination procedure with elemental bromine and a set of Lewis acids (BBr3, BF3 × Et2O, AlBr3, FeBr3, ZnBr2, TiBr4, SiBr4, SnBr4, VBr3) or a radical starter like dibenzoylperoxide (DBPO) in appropriate solvents at varied temperature. The present approach to electrophilic sites relies on the well-known electrophilic aromatic substitution or addition of bromine with aromatic structural units. In addition to the use of bromine, the introduction of haloalkyl groups was also investigated here using bis-electrophiles or haloalcohols and Brønsted acids. The advantages and drawbacks of the studied reaction conditions, the obtained degree of bromination as analyzed by X-ray photoelectron spectroscopy (XPS) and the amount of introduced bromine that can be substituted by a nucleophile are presented and discussed. 相似文献
66.
Conrad F Massue C Kühl S Kunkes E Girgsdies F Kasatkin I Zhang B Friedrich M Luo Y Armbrüster M Patzke GR Behrens M 《Nanoscale》2012,4(6):2018-2028
Nanostructured Cu(x)Zn(1-x)Al(2)O(4) with a Cu:Zn ratio of ?:? has been prepared by a microwave-assisted hydrothermal synthesis at 150 °C and used as a precursor for Cu/ZnO/Al(2)O(3)-based catalysts. The spinel nanoparticles exhibit an average size of approximately 5 nm and a high specific surface area (above 250 m(2) g(-1)). Cu nanoparticles of an average size of 3.3 nm can be formed by reduction of the spinel precursor in hydrogen and the accessible metallic Cu(0) surface area of the reduced catalyst was 8 m(2) g(-1). The catalytic performance of the material in CO(2) hydrogenation and methanol steam reforming was compared with conventionally prepared Cu/ZnO/Al(2)O(3) reference catalysts. The observed lower performance of the spinel-based samples is attributed to a lack of synergetic interaction of the Cu nanoparticles with ZnO due to the incorporation of Zn(2+) in the stable spinel lattice. Despite its lower performance, however, the nanostructured nature of the spinel catalyst was stable after thermal treatment up to 500 °C in contrast to other Cu-based catalysts. Furthermore, a large fraction of the re-oxidized copper migrates back into the spinel upon calcination of the reduced catalyst, thereby enabling a regeneration of sintered catalysts after prolonged usage at high temperatures. Similarly prepared samples with Ga instead of Al exhibit a more crystalline catalyst with a spinel particle size around 20 nm. The slightly decreased Cu(0) surface area of 3.2 m(2) g(-1) due to less copper incorporation is not a significant drawback for the methanol steam reforming. 相似文献
67.
AdamsFriedrich 《制造技术与机床》2005,(5):69-71
机器的控制电路分为两大部分:一部分是负责机器运行功能的控制电路;另一部分是实现安全保护功能的控制电路(图1).控制电路的划分在国际标准中已有规定,而且有关"工作保护"的条目,在许多国家的法规中也可以找到. 相似文献
68.
Nasdala L Ruschel K Rhede D Wirth R Kerschhofer-Wallner L Kennedy AK Kinny PD Finger F Groschopf N 《Chimia》2010,64(10):705-711
The internal textures of crystals of moderately radiation-damaged monazite-(Ce) from Moss, Norway, indicate heavy, secondary chemical alteration. In fact, the cm-sized specimens are no longer mono-mineral monazite but rather a composite consisting of monazite-(Ce) and apatite pervaded by several generations of fractures filled with sulphides and a phase rich in Th, Y, and Si. This composite is virtually a 'pseudomorph' after primary euhedral monazite crystals whose faces are still well preserved. The chemical alteration has resulted in major reworking and decomposition of the primary crystals, with potentially uncontrolled elemental changes, including extensive release of Th from the primary monazite and local redeposition of radionuclides in fracture fillings. This seems to question the general alteration-resistance of orthophosphate phases in a low-temperature, 'wet' environment, and hence their suitability as potential host ceramics for the long-term immobilisation of radioactive waste. 相似文献
69.
Franziska Brauneck Elisa Seubert Jasmin Wellbrock Julian Schulze zur Wiesch Yinghui Duan Tim Magnus Carsten Bokemeyer Friedrich Koch-Nolte Stephan Menzel Walter Fiedler 《International journal of molecular sciences》2021,22(23)
This study aimed to characterize different natural killer (NK) cell phenotypes on bone marrow and peripheral blood cells from acute myeloid leukemia (AML) patients and healthy donors (HDs). Our data show that CD56dimCD16− and CD56brightCD16− NK cells represent the predominant NK cell subpopulations in AML, while the CD56dimCD16+ NK cells are significantly reduced compared to HDs. Moreover, TIGIT+ and PVRIG+ cells cluster on the CD56dimCD16+ subset whereas CD39+ and CD38+ cells do so on CD56brightCD16− NK cells in AML. Furthermore, functional effects of (co-)blockade of TIGIT and CD39 or A2AR on NK cell functionality were analyzed. These experiments revealed that the single blockade of the TIGIT receptor results in an increased NK-92 cell-mediated killing of AML cells in vitro. Combined targeting of CD39 or A2AR significantly augments the anti-TIGIT-mediated lysis of AML cells. Our data indicate that distinct NK cell subsets in AML exhibit different immunosuppressive patterns (via the TIGIT/PVRIG receptors and the purinergic pathway). In summary, we conclude that TIGIT, CD39, and A2AR constitute relevant inhibitory checkpoints of NK cells in AML patients. A combinatorial blockade synergistically strengthens NK-92 cell-mediated cytotoxicity. As inhibitors of TIGIT, CD39, and A2AR are clinically available, studies on their combined use could be conducted in the near future. 相似文献
70.
Tacke R Popp F Müller B Theis B Burschka C Hamacher A Kassack MU Schepmann D Wünsch B Jurva U Wellner E 《ChemMedChem》2008,3(1):152-164
Haloperidol (1 a), a dopamine (D(2)) receptor antagonist, is in clinical use as an antipsychotic agent. Carbon/silicon exchange (sila-substitution) at the 4-position of the piperidine ring of 1 a (R(3)COH --> R(3)SiOH) leads to sila-haloperidol (1 b). Sila-haloperidol was synthesized in a new multistep synthesis, starting from tetramethoxysilane and taking advantage of the properties of the 2,4,6-trimethoxyphenyl unit as a unique protecting group for silicon. The pharmacological profiles of the C/Si analogues 1 a and 1 b were studied in competitive receptor binding assays at D(1)-D(5), sigma(1), and sigma(2) receptors. Sila-haloperidol (1 b) exhibits significantly different receptor subtype selectivities from haloperidol (1 a) at both receptor families. The C/Si analogues 1 a and 1 b were also studied for 1) their physicochemical properties (log D, pK(a), solubility in HBSS buffer (pH 7.4)), 2) their permeability in a human Caco-2 model, 3) their pharmacokinetic profiles in human and rat liver microsomes, and 4) their inhibition of the five major cytochrome P450 isoforms. In addition, the major in vitro metabolites of sila-haloperidol (1 b) in human liver microsomes were identified using mass-spectrometric techniques. Due to the special chemical properties of silicon, the metabolic fates of the C/Si analogues 1 a and 1 b are totally different. 相似文献