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排序方式: 共有1925条查询结果,搜索用时 15 毫秒
1.
目的探讨lncRNA DNM3OS对直肠癌SW-480细胞的增殖、凋亡以及放射敏感性的影响及分子机制。方法选取30例直肠癌患者癌组织及癌旁组织,RT-qPCR检测DNM3OS和miR-193a-3p的表达水平;将抑制DNM3OS的表达载体、过表达miR-193a-3p载体转染至SW-480细胞,将DNM3OS与抑制miR-193a-3p的表达载体共转染至SW-480细胞,并用4 Gy射线照射;细胞集落形成实验检测细胞放射敏感性;四甲基偶氮唑盐比色法(MTT)检测SW-480细胞增殖抑制率;流式细胞测量术检测SW-480细胞凋亡;双荧光素酶报告基因实验检测DNM3OS和miR-193a-3p的靶向调控。结果直肠癌组织中DNM3OS表达水平高于癌旁组织,miR-193a-3p表达水平低于癌旁组织(P<0.05)。抑制DNM3OS表达或过表达miR-193a-3p后,SW-480细胞增殖抑制率和凋亡率升高(P<0.05);经射线照射后细胞存活分数降低,细胞增殖抑制率和凋亡率升高(P<0.05)。DNM3OS靶向调控miR-193a-3p,干扰miR-193a-3p表达逆转了...  相似文献   
2.
We propose a high order finite difference linear scheme combined with a high order bound preserving maximum-principle-preserving (MPP) flux limiter to solve the incompressible flow system. For such problem with highly oscillatory structure but not strong shocks, our approach seems to be less dissipative and much less costly than a WENO type scheme, and has high resolution due to a Hermite reconstruction. Spurious numerical oscillations can be controlled by the weak MPP flux limiter. Numerical tests are performed for the Vlasov-Poisson system, the 2D guiding-center model and the incompressible Euler system. The comparison between the linear and WENO type schemes, with and without the MPP flux limiter, will demonstrate the good performance of our proposed approach.  相似文献   
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Solar urticaria (SU) is a rare form of urticaria with a pathogenesis that is poorly understood. It affects all skin types, can be difficult to diagnose, and is challenging to manage effectively. We conducted a retrospective review of patients with SU in our institution. A total of 83 patients (56 females) were identified as having SU. The mean age was 32 years (7–74) at first development of symptoms/signs of SU. Pruritus was the most common symptom reported (79%). Of the 60 patients who underwent monochromator testing at least once, 35 had SU confirmed with most reacting to visible light and UVA, or to UVA alone. Antihistamines and sun avoidance remain the mainstay treatment for SU but other treatments, including omalizumab, are of potential interest in treating patients with recalcitrant SU. The characterisation of this large case series of patients may help dermatologists recognise and manage this rare disorder appropriately.  相似文献   
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目的研究真实世界中高血压病住院患者的临床特征以及各中医证型分布特点及中药处方用药规律。方法基于回顾性研究的方法,选择本院2018年1月—2019年12月信息系统(hospital information systerm,HIS)中主诊断为高血压的住院患者,采集其入院及治疗过程中的信息,使用频数分析和关联规则分析方法进行分析。结果共纳入2064例高血压患者,其中男性1007人(49%),女性1057人(51%);以3级高血压最多见(54%);证型分布上以痰瘀互结最多见(47%);各证型发病的平均年龄以肝火亢盛年龄最低(58岁),肾气虚证型最高(68岁)。高血压第2诊断常见合并病/症以冠心病为主(40%),其次为脑梗死(20%);住院时间的节气分布方面,总体上看以小满发病人数最多,其次是立夏、处暑、芒种、小暑等,各证型又不相同。中药使用方面:处方中共包括了235种中药材,各个证型高频用药以川芎使用的频次最高,其他使用频次较多的包括天麻、当归、半夏、丹参等。5个证型共计产生核心药对44对,肝火亢盛证以天麻配伍川牛膝、杜仲置信度最高;肾气虚证以川芎配伍山药、当归置信度最高;痰瘀互结证以川芎配伍当归、地龙置信度最高;阴虚阳亢证以川芎配伍半夏、酸枣仁置信度最高。结论基于临床特征及处方用药分析,高血压的基本病理因素以瘀、痰、虚为主,用药主要为活血通络、平肝补肾之品,常用核心药物为川芎,根据不同证型常以天麻、山药、当归、半夏等与之相配伍应用。  相似文献   
7.
India has set aggressive targets to install more than 400 GW of wind and solar electricity generation by 2030, with more than two-thirds of that capacity coming from solar. This paper examines the electricity and carbon mitigation costs to reliably operate India’s grid in 2030 for a variety of wind and solar targets (200 GW to 600 GW) and the most promising options for reducing these costs. We find that systems where solar photovoltaic comprises only 25 to 50% of the total renewable target have the lowest carbon mitigation costs in most scenarios. This result invites a reexamination of India’s proposed solar-majority targets. We also find that, compared to other regions and contrary to prevailing assumptions, meeting high renewable targets will avoid building very few new fossil fuel (coal and natural gas) power plants because of India’s specific weather patterns and need to meet peak electricity demand. However, building 600 GW of renewable capacity, with the majority being wind plants, reduces how often fossil fuel power plants run, and this amount of capacity can hold India’s 2030 emissions below 2018 levels for less than the social cost of carbon. With likely wind and solar cost declines and increases in coal energy costs, balanced or wind-majority high renewable energy systems (600 GW or 45% share by energy) could result in electricity costs similar to a fossil fuel-dominated system. As an alternative strategy for meeting peak electricity demand, battery storage can avert the need for new fossil fuel capacity but is cost effective only at low capital costs ( USD 150 per kWh).

India emitted 3.2 billion metric tons of CO2e in 2016, or 6% of annual global greenhouse gas emissions, placing it third only to China and the United States (1). One-third of these emissions were from coal-based electricity. At the same time, both per capita emissions and energy use remain well below global averages, suggesting a massive potential for growth of electricity generation and emissions (1). India’s primary energy demand is expected to double by 2040 compared to 2017 (2). Whether this energy comes from fossil or low-carbon sources will significantly affect the ability to limit average global temperature rise to below 2 °C.India is already pursuing significant technology-specific renewable energy targets—100 GW of solar and 60 GW of wind by 2022—and, in its Nationally Determined Contributions (NDC), committed to a 40% target for installed generation capacity from nonfossil fuel sources by 2030 (3). In 2019, in part to fulfill its NDC commitment, the Indian government proposed to install 440 GW of renewable energy capacity by 2030, with 300 GW of solar and 140 GW of wind capacity (4). Although costs of solar photovoltaic (PV) and wind technologies have declined significantly in recent years (57), the low cost of coal and integration costs associated with variable renewable energy (VRE) technologies like wind and solar may hinder India’s cost-effective transition to a decarbonized electricity system. This paper seeks to answer a number of questions that arise in the Indian context. What targets for wind and solar capacity have the lowest associated integration costs? Will these targets significantly offset the need to build fossil fuel generation capacity? What additional measures can we take to mitigate VRE integration costs?Merely comparing the levelized costs of VRE with the costs of conventional generation ignores additional cost drivers, which depend on the timing of VRE production and other conditions in the power system (8, 9). Quantifying these drivers requires models that choose lowest-cost generation capacity portfolios and simulate optimal system operation with detailed spatiotemporal data. Several prior studies address these system-level integration costs in a capacity expansion planning framework (1016), often making decisions based on a limited sample of representative hours. Other studies explicitly estimate the relationship between long-run economic value (including integration costs) of VRE penetration levels (17, 18) but do not include VRE investment costs in their analysis. Few prior studies explore the impacts of high VRE penetration on India’s electricity system, and those that do either use the capacity expansion framework and do not evaluate the economic value of multiple VRE targets (4, 19, 20) or do not optimize capacity build around proposed VRE targets (21).Here we address this gap by estimating how different VRE targets affect the cost to reliably operate the Indian electricity system. To do so, we work with three interrelated models. First, using a spatially explicit model for VRE site selection, we identify the lowest levelized cost wind and solar sites to meet different VRE capacity targets, and study how the resource quality—and corresponding levelized cost—of selected sites changes with increasing VRE targets.Second, using a capacity investment model that accounts for VRE production patterns and optimal dispatch of hydropower and battery storage, we determine the capacity requirements and investment costs for coal, combined cycle gas turbines (CCGT), and combustion turbine (CT) peaker plants. Due to uncertainties in their future deployment (22), and because their current targets are relatively low (4), we did not consider new nuclear or hydro capacity in the main scenarios but include those in the sensitivity scenarios presented in SI Appendix, section 2. Third, we use a unit commitment and economic dispatch model to simulate hourly operation of the electricity system and estimate annual system operational costs. This model captures important technical constraints, including minimum operating levels, daily unit commitment for coal and natural gas plants, and energy limits on hydropower and battery storage. Rather than cooptimize VRE capacity, we compute the system-level economic value of a range of VRE targets by comparing the sum of the avoided new conventional capacity and energy generation costs to a no-VRE scenario. The net cost for a scenario is then the difference between the levelized cost of the VRE and the system-level economic value. Materials and Methods provides more detail on this process.Our results show that, despite greater levelized cost reduction forecasts for solar PV compared to wind technologies, VRE targets with greater amounts of wind have the lowest projected net carbon mitigation costs. This finding is robust to a range of scenarios, including low-cost solar and storage, and lower minimum generation levels for coal generators.We find that, although VRE production displaces energy production from conventional generators, it does very little to defer the need for capacity from those generators due to low correlation between VRE production and peak demand. Our findings suggest that VRE in India avoids far less conventional capacity than VRE in other regions in the world. These capacity requirements are slightly mitigated if India’s demand patterns evolve to more closely resemble demand in its major cities. Overall, we conclude that the importance of choosing the right VRE mix is significant when measured in terms of carbon mitigation costs: Whereas most solar-majority scenarios we examined lead to costs greater than or equal to estimates of the social cost of carbon (SCC), wind-majority mixes all cost far less than the SCC.  相似文献   
8.
The emulation of the reflectance of green leaf in the solar spectral band (300–2500 nm) has garnered increasing attention from researchers. Currently, various materials have been proposed and investigated as potential bionic leaves. However, the problems such as poor weather durability, heavy metal pollution, and complex preparation technology still persist. Herein, a bionic leaf is prepared from an ultramarine green pigment as the functional material, polyvinylidene fluoride (PVDF) as the film-forming material, and LiCl as the humidizer. To prepare the ultramarine green pigment, the sulfur anion is added into the β cage of the 4A zeolite. The mechanisms and properties were discussed based on X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and spectroscopic methods. The results show that the as-fabricated bionic leaf based on the 4A zeolite-derived ultramarine green pigment was able to demonstrate a high spectral similarity coefficient of 0.91 with the green leaf. Furthermore, the spectral similarity coefficient was increased to 0.94 after being subjected to a simulated rainforest environment for 48 h, which indicated its high weather durability.  相似文献   
9.
目的 探讨不同放疗剂量对接受放(化)疗的食管癌术后局部区域复发患者的影响。方法 收集2009—2014年间河北医科大学第四医院收疗的331例食管癌术后局部区域复发患者资料,回顾性分析其复发部位、不同放疗剂量对患者预后影响及其独立性预后影响因素等。Kaplan-Meier法计算生存率并log-rank法检验和单因素预后分析,Cox模型多因素预后分析。结果 1、3、5年总生存率分别为54.3%、23.2%、16.6%,中位生存时间13.4个月(95%CI为11.7~15.0个月)。放疗剂量<60Gy和≥60Gy组患者中位生存时间分别为10.8个月和13.9个月(P=0.013)。分层分析结果显示年龄<60岁、无吸烟史、无饮酒史、无家族史、胸上段、左侧开胸、N0分期、阳性淋巴结对数比(LODDS)<0.030、复发时间≥13.1个月和复发部位≥2个组患者在接受≥60Gy的放疗剂量时预后较好(P值分别为0.038、0.033、0.001、0.003、0.018、0.010、0.041、0.039、0.043、0.007)。且≥60Gy剂量组患者近期疗效明显优于<60Gy剂量组患者(P<0.001),且不增加其≥2级放射性胃炎(P=0.977)和放射性肺炎(P=0.444)的发生率。多因素分析结果显示原发病变LODDS大小、处方剂量及近期疗效为影响患者预后的独立性因素(P值分别为0.006、0.008、<0.001)。结论 食管癌术后局部区域复发患者放疗处方剂量≥60Gy可使患者明显受益,但还需要进行大宗病例的前瞻性研究证实。  相似文献   
10.
A kind of low recombination firing-through screen-printing aluminum (Al) paste is proposed in this work to be used for a boron-diffused N-type solar cell front side metallization. A front side fire-through contact (FTC) approach has been carried out for the formation of local contacts for a front surface passivated solar cell. With a low contact resistivity (ρc) of 1.0 mΩ·cm2, good ohmic contact between the boron-doped front surface of the silicon sample and the Al paste was realized. To obtain a good energy conversion efficiency, a balance can be achieved between the open circuit voltage (Voc) and contact resistivity (ρc) of the cell by combining suitable Al powders and appropriate additives. The detailed micro-contact difference in Si/metallization between the firing-through Al paste and silver-aluminum (Ag-Al) paste was analyzed. The dark saturation current density beneath the metal contact (J0, metal) of the Si/metallization region using our firing-through Al paste was discussed, which was proven to be 61% lower than using Ag-Al paste. The pseudo energy conversion efficiency of the cell using Al paste measured by Suns-VOC was also higher than using Ag-Al paste. The role of Al paste in low surface metal recombination is discussed. The utilization of this new kind of Al paste was much cheaper and more convenient, compared to the traditional process using Ag or Ag-Al paste.  相似文献   
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