检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

立式加工中心铣圆精度分析与提升方法研究

机械工程与自动化 2024年第3期 110-113页

作者：徐永明沈阳机床股份有限公司辽宁沈阳110142

在数控机床长期使用过程中,滚珠丝杠、导轨及轴承存在一定程度的磨损,且数控系统动态响应不稳定,伺服优化不完善,也会影响数控机床的圆度误差。为此,提出了一种能够提升立式加工中心铣削圆精度的新方法。首先介绍立式加工中心加工中存... 详细信息

在数控机床长期使用过程中,滚珠丝杠、导轨及轴承存在一定程度的磨损,且数控系统动态响应不稳定,伺服优化不完善,也会影响数控机床的圆度误差。为此,提出了一种能够提升立式加工中心铣削圆精度的新方法。首先介绍立式加工中心加工中存在的精度问题;然后提出一种改进的立式加工中心加工方法,通过优化切削参数、建立循圆加工能力指数计算公式,根据实验找到机床加工极限进给,并通过设置合适的加工能力指数实现了铣削圆加工精度的提升;最后通过实验验证该方法的有效性,并进行综合评价和分析。实验通过调整系统参数更改反向间隙值来提高加工中心的精度,同时将参数K定义为设备的循圆加工能力指数,根据切削验证,得出K≤600时,插补铣削精度<0.01 mm;K为1 800时为机床极限加工进给。分析结果为立式加工中心精度提升提供了新的方法和思路。

关键词：立式加工中心孔加工精度提升刀具寿命

冠突散囊菌GT-1固态发酵对低次烟叶品质的影响

在线全文

学校读者我要写书评

暂无评论

陕西科技大学学报 2024年第3期42卷 38-45页

作者：李萌曾婷婷杨金初徐永明李欢马林饶智郑州轻工业大学烟草科学与工程学院河南郑州450001 河南中烟工业有限责任公司技术中心河南郑州450000 广西中烟工业有限责任公司柳州卷烟厂广西柳州545001 红云红河烟草(集团)有限责任公司云南昆明650202

为探究应用冠突散囊菌固态发酵提升低次烟叶品质的可行性,从茯砖茶中分离筛选冠突散囊菌并接种于低次烟叶进行固态发酵,通过感官评吸考察固态发酵对烟叶品质的影响,应用同时蒸馏萃取和GC/MS检测固态发酵过程中1、3、5、7 d的烟叶主要致... 详细信息

为探究应用冠突散囊菌固态发酵提升低次烟叶品质的可行性,从茯砖茶中分离筛选冠突散囊菌并接种于低次烟叶进行固态发酵,通过感官评吸考察固态发酵对烟叶品质的影响,应用同时蒸馏萃取和GC/MS检测固态发酵过程中1、3、5、7 d的烟叶主要致香成分的变化.结果表明,从茯砖茶中成功分离到候选菌株GT-1,经形态和分子生物学鉴定确认为冠突散囊菌.将GT-1接种于低次烟叶进行固态发酵,发酵5天烟叶感官质量最佳,香气量、香气质、浓度和余味较对照均有较为明显改善.发酵烟叶中共检测出33种主要致香成分,包含16种类胡萝卜素降解产物、9种芳香族氨基酸转化产物、1种叶绿素降解产物、1种类西柏烷降解产物、6种美拉德反应产物.随着固态发酵时间的延长,烟叶主要致香成分总量呈现先上升后下降的趋势,致香成分总量在第5 d达到最高,为402.03μg/g;相较于未发酵烟叶,致香成分含量提高了22.54%,其中4,7,9-巨豆三烯-3-酮、香叶基丙酮、二氢猕猴桃内酯、苯甲醇、苯乙醇、2-乙酰基吡咯等致香物质含量显著提高,极大的丰富了烟气的甘甜香、烟草香、果香、花香等香气.冠突散囊菌固态发酵可提高烟叶香气物质含量和种类,有效提升低次烟叶品质.

关键词：冠突散囊菌固态发酵低次烟叶致香成分发酵时间

Effects of epidermal growth factor on the growth of human gastric cancer cell and the implanted tumor of nude mice

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2002年第3期8卷 455-458页

作者： Lu Xia Yao-Zong Yuan Chun-Di xu yong-Pin Zhang ming-ming Qiao Jia-xu xu,Department of Gastroenterology,Ruijin Hospital,Shanghai Second Medical University,Shanghai 200025,China Department of Gastroenterology Ruijin Hospital Shanghai Second Medical University Shanghai 200025 China. xialu@***

AIM: Epidermal growth factor (EGF) plays an important role in the regulation of gastrointestinal tissue growth and development, and it can stimulate epithelial proliferation, cell differentiation and growth. It has been established that the EGF can promote gastric cytoprotection and ulcer healing. But the potential ability of EGF to regulate the gastric cancer growth is unknown. This study is to investigate the influence of EGF on human gastric cancer cell and the implanted tumor growth of nude mice. METHODS: The cell growth rates of human gastric adenocarcinoma cell lines MKN-28, MKN-45, SGC-7901 and normal human gastric epithelial cells 3T3 were assessed when incubated with recombinant human EGF (rhEGF, 0.05, 0.1, 0.5, 1.0, 10, 50, 100 mg.L(-1)) using MTT method. The cells of MKN-28, MKN-45, SGC-7901 (gastric cancer tissue 1.5mm(3)) were implanted in the BALB/cA nude mice for 10 *** EGF was given intraperitoneally (15, 30, 60 ***(-1)) for 3 weeks. The body weights of the tumor-bearing animals and their tumor mass were measured afterwards to assess the mitogenic effect of rhEGF in the nude mice. RESULTS: Within the concentration range of 0.05-100mg.L(-1), rhEGF could increase the cell growth of normal 3T3 cells (cell growth rate 100% vs 102.8%, P0.05), the mean tumor mass of SGC-7901 cell were 1.53 g, 1.07 g, 1.20 g/NS group 1.07 g (P>0.05), and for MKN-45 cell, the tumor mass were respectively 1.92 g, 1.29 g, 1.77 /NS group 1.82 g (P>0.05). So rhEGF had no obvious effect on implanted MKN-28, SGC-7901 and MKN-45 tumor growth. CONCLUSION: EGF has no stimulating effect on the human gastric cancer cell growth neither in vitro nor in vivo.

关键词： Animals Cell Division Epidermal Growth Factor Humans Male Mice Mice, Nude Neoplasm Transplantation Recombinant Proteins Stomach Neoplasms Transplantation, Heterologous Tumor Cells, Cultured

Ultrahigh spatiotemporal resolution beam signal reconstruction with bunch phase compensation

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第5期35卷 99-108页

作者： You-ming Deng yong-Bin Leng Xing-Yi xu Jian Chen Yi-Mei Zhou Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China University of the Chinese Academy of Sciences Beijing 100049China Shanghai Synchrotron Radiation Facility Chinese Academy of SciencesShanghai 201204China University of Science and Technology of China Hefei 230026China Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201204China

Various electromagnetic signals are excited by the beam in the acceleration and beam-diagnostic elements of a particle *** is important to obtain time-domain waveforms of these signals with high temporal resolution for research,such as the study of beam–cavity interactions and bunch-by-bunch parameter ***,a signal reconstruction algorithm with ultrahigh spatiotemporal resolution and bunch phase compensation based on equivalent sampling is proposed in this *** with traditional equivalent sampling,the use of phase compensation and setting the bunch signal zero-crossing point as the time reference can construct a more accurate reconstructed *** basic principles of the method,simulation,and experimental comparison are also *** on the beam test platform of the Shanghai Synchrotron Radiation Facility(SSRF)and the method of experimental verification,the factors that affect the reconstructed signal quality are analyzed and discussed,including the depth of the sampled data,quantization noise of analog-to-digital converter,beam transverse oscillation,and longitudinal *** results of the beam experiments show that under the user operation conditions of the SSRF,a beam excitation signal with an amplitude uncertainty of 2%can be reconstructed.

关键词： Turn-by-turn bunch phase compensation technique Equivalent sampling Signal reconstruction algorithm Ultrahigh spatiotemporal resolution SSRF

Tea Consumption is Associated with Increased Risk of Kidney Stones in Northern Chinese： A Cross-sectional Study

在线全文

学校读者我要写书评

暂无评论

Biomedical and Environmental Sciences 2017年第12期30卷 922-926页

作者： WU Zhong Biao JIANG Tian LIN Guo Bing WANG You Xin ZHOU yong CHEN Zhen Qian xu yong ming YE Hai Bo CHEN Bo Jun BAO Xiao Zhao ZHANG Cun ming Department of Urology The Affiliated Wenling Hospital of Wenzhou Medical University Wenling 317500 Zhejiang China Research Center for Translational Medicine The Affiliated Wenling Hospital of Wenzhou Medical University Wenling 317500 Zhejiang China Beijing Key Laboratory of Clinical Epidemiology School of Public Health Capital Medical University Beijing 100069 China Beijing Institute of Heart Lung and Blood Vessel Diseases Bejing Anzhen Hospital Capital Medical University Beijing 100029 China Department of Radiology The Affiliated Wenling Hospital of Wenzhou Medical University Wenling 317500 Zhejiang China

Kidney stones are a common urinary system condition that can progress to kidney disease. Previous studies on the association between tea consumption and kidney stones are inconsistent. A cross-sectional study to investigate the association between tea consumption and kidney stones was conducted from 2013 to 2014 and recruited 9,078 northern Chinese adults. A total of 8,807 participants were included in the final analysis. Participants＇ prevalence of kidney stones was 1.07%, 1.73%, and 2.25% based on their tea consumption frecluencv of never, occasionally,

关键词： Increased Risk of Kidney Stones Northern Chinese Cross-sectional Study

Activity and Composition of Ammonia-Oxidizing Bacteria in an Aquic Brown Soil as Influenced by Land Use and Fertilization

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2010年第6期20卷 789-798页

作者： YU Wan-Tai,xu yong-Gang,BI ming-Li,MA Qiang and ZHOU Hua Institute of Applied Ecology,Chinese Academy of Sciences,Shenyang 110016 (China) Institute of Applied Ecology Chinese Academy of Sciences Shenyang 110016 (China)

The effects of long-term (19 years) different land use and fertilization on activity and composition of ammonia-oxidizing bacteria (AOB) in an aquic brown soil were investigated in a field experiment in Liaoning Province,*** 19-year experiment conducted from 1990 to 2008 involved seven treatments designed: cropping rotation of soybean-corn-corn with no fertilizer (control,CK),recycled manure (RM),fertilizer nitrogen (N),phosphorous (P) and potassium (K) (NPK),NPK+RM,and no-crop bare land,mowed fallow,and non-mowed *** results showed that the potential nitrification rates of the RM,NPK+RM,mowed fallow,and non-mowed fallow treatments were significantly higher (P < 0.05) than those of the CK and NPK treatments,indicating that the long-term applications of recycled manure and return of plant residues both significantly increased the activity of *** the application of NPK did not enhance soil potential nitrification because of decreased pH,available K had an important effect on potential *** gradient gel electrophoresis (DGGE) fingerprint profiles showed that no-crop treatments had an increase in the diversity of the AOB community compared to the CK,RM,and NPK treatments,implying that agricultural practices,especially tillage,had an adverse effect on the soil AOB *** NPK+RM treatment had the most diverse DGGE patterns possibly because of the increased available P in this treatment.A phylogenetic analysis showed that most of the DGGE bands derived belonged to Nitrosospira cluster 3,not Nitrosospira cluster *** demonstrated that different land use and fertilization significantly influenced the activity and composition of the AOB community by altering the soil properties,mainly including pH,total C,available K,and available P.

关键词： community composition denaturing gradient gel electrophoresis nitrification Nitrosospira phylogenetic analysis

Influence of erosion voids and traffic loads on buried large-diameter reinforced concrete pipes

在线全文

学校读者我要写书评

暂无评论

Underground Space 2024年第4期17卷 120-131页

作者： ming xu Dawei Shen Department of Civil Engineering Tsinghua UniversityBeijing 100084China Beijing Institute of Technology Beijing 100081China

Geotechnical centrifuge tests were conducted to examine the influence of invert voids and surface traffic loads on 1400 mm diameter reinforced concrete pipes buried with a shallow soil cover depth of 700 *** formation beneath the pipe was simulated during centrifuge *** test results revealed that before void formation,the surface load directly above the middle of the pipe caused a significant increase in not only the circumferential bending moments but also the longitudinal bending moments,the latter of which was considerable and could not be *** formation beneath the middle of the pipe led to a reduction in both the circumferential bending moments and longitudinal bending moments at all measuring positions,i.e.,crown,springline,and *** most significant reduction occurred at the invert,and there was even a reversal in the sign of the invert longitudinal bending moment.A comparison was made between centrifuge tests with erosion voids and surface loads at different horizontal positions,which had a marked influence even when the positions differed by half a pipe *** rotation played an important role in relieving large bending moments of pipe barrels in a jointed pipeline when the void and surface load were located at the joint.

关键词： Centrifuge test Erosion void Reinforced concrete pipe Traffic loading Longitudinal bending moment Joint rotation

The Essential 2-rank for Classical Groups

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2024年第9期40卷 2169-2186页

作者： Jian Bei AN yong xu Department of Mathematics University of AucklandAucklandNew Zealand School of Mathematics and Statistics He’nan University of Science and TechnologyLuoyang 471023P.R.China

Let G be a symplectic or orthogonal group defined over a finite field with odd characteristic and let D≤G be a Sylow *** this paper,we classify the essential 2-subgroups and determine the essential 2-rank of the Frobenius category FD(G).Together with the results of An–Dietrich and Cao–An–Zeng,this completes the work of essential subgroups and essential ranks of classical groups.

关键词： Frobenius category conjugation families essential 2-rank symplectic groups orthogonal groups

Dual Frequency Transformer for Efficient SDR-to-HDR Translation

在线全文

学校读者我要写书评

暂无评论

Machine Intelligence Research 2024年第3期21卷 538-548页

作者： Gang xu Qibin Hou ming-ming Cheng Tianjin Media Computing Center College of Computer ScienceNankai UniversityTianjin300000China

The SDR-to-HDR translation technique can convert the abundant standard-dynamic-range (SDR) media resources to high-dynamic-range (HDR) ones, which can represent high-contrast scenes, providing more realistic visual experiences. While recent vision Transformers have achieved promising performance in many low-level vision tasks, there are few works attempting to leverage Transformers for SDR-to-HDR translation. In this paper, we are among the first to investigate the performance of Transformers for SDR-to-HDR translation. We find that directly using the self-attention mechanism may involve artifacts in the results due to the inappropriate way to model long-range dependencies between the low-frequency and high-frequency components. Taking this into account, we advance the self-attention mechanism and present a dual frequency attention (DFA), which leverages the self-attention mechanism to separately encode the low-frequency structural information and high-frequency detail information. Based on the proposed DFA, we further design a multi-scale feature fusion network, named dual frequency Transformer (DFT), for efficient SDR-to-HDR translation. Extensive experiments on the HDRTV1K dataset demonstrate that our DFT can achieve better quantitative and qualitative performance than the recent state-of-the-art methods. The code of our DFT is made publicly available at https://***/CS-Gangxu/DFT.

关键词： Standard-dynamic-range to high-dynamic-range(SDR-to-HDR)translation Transformer dual frequency attention(DFA) frequency-aware feature decomposition efficient model