背景:既往认为黄韧带骨化在人群中罕见发生,随着研究深入,发现其发病率逐渐上升,这引起大量学者的研究兴趣。目的:通过检索科学引文索引数据库核心集自1999年以来的有关黄韧带骨化的研究成果,使用文献计量学方法对数据进行可视化分析,...背景:既往认为黄韧带骨化在人群中罕见发生,随着研究深入,发现其发病率逐渐上升,这引起大量学者的研究兴趣。目的:通过检索科学引文索引数据库核心集自1999年以来的有关黄韧带骨化的研究成果,使用文献计量学方法对数据进行可视化分析,回顾黄韧带骨化的研究历史,指示重要文献,梳理研究热点,为学者寻找研究方向提供思路。方法:以Web of Science核心集数据库为主,搜索并筛选黄韧带骨化相关论文,使用VOSviewer 1.6.19和CiteSpace 6.2.R6软件对年度发文量、研究国家、机构、被引文献、期刊、作者和关键词等进行可视化分析。结果与结论:①共纳入347篇文献,自1999年发文量呈螺旋上升,中国研究较日本起步晚,但是发文量后来居上,北京大学是发文量最多的机构,北京大学的陈仲强教授是发文量最多的学者。②被引用最多的10篇文献中5篇都与黄韧带骨化的手术治疗有关。③去除与研究主题直接相关的关键词,综合词频和中介中心性的结果发现,“胸椎脊髓病”“硬膜骨化”“微创手术”“后纵韧带骨化”处于领域研究的核心地位。④关键词聚类分析显示,黄韧带骨化的临床表现和手术治疗在疾病的研究中占比较大。⑤关键词时间线图及关键词突现分析显示,“微创手术”作为关键词出现在2015年前后,是突现强度最高的关键词,也是突现开始时间最晚的关键词,2019年开始受到学者广泛关注,关键词“硬膜骨化”的突现尚未结束。⑥黄韧带骨化的手术治疗一直处于研究前沿,微创手术方式的开发和研究、黄韧带骨化继发硬膜骨化的研究是该领域的研究热点。展开更多
To enhance the catalytic activity of copper ferrite(CuFe_(2)O_(4))nanoparticle and promote its application as combustion catalyst,a low-cost silicon dioxide(SiO_(2))carrier was employed to construct a novel CuFe_(2)O_...To enhance the catalytic activity of copper ferrite(CuFe_(2)O_(4))nanoparticle and promote its application as combustion catalyst,a low-cost silicon dioxide(SiO_(2))carrier was employed to construct a novel CuFe_(2)O_(4)/SiO_(2)binary composites via solvothermal method.The phase structure,morphology and catalytic activity of CuFe_(2)O_(4)/SiO_(2)composites were studied firstly,and thermal decomposition,combustion and safety performance of ammonium perchlorate(AP)and 1,3,5-trinitroperhydro-1,3,5-triazine(RDX)with it affecting were then systematically analyzed.The results show that CuFe_(2)O_(4)/SiO_(2)composite can remarkably either advance the decomposition peak temperature of AP and RDX,or reduce the apparent activation energy at their main decomposition zone.Moreover,the flame propagation rate of RDX was promoted by about 2.73 times with SiO_(2)content of 3 wt%,and safety property of energetic component was also improved greatly,in which depressing the electrostatic discharge sensitivity of pure RDX by about 1.89 times.In addition,the effective range of SiO_(2)carrier content in the binary catalyst is found to be 3 to 5 wt%.Therefore,SiO_(2)opens a new insight on the design of combustion catalyst carrier and will promote the application of CuFe_(2)O_(4)catalyst in solid propellant.展开更多
Neuroprotection by ischemic preconditioning has been confirmed by many studies, but the precise mechanism remains unclear. In the present study, we performed cerebral ischemic pre- conditioning in rats by simulating a...Neuroprotection by ischemic preconditioning has been confirmed by many studies, but the precise mechanism remains unclear. In the present study, we performed cerebral ischemic pre- conditioning in rats by simulating a transient ischemic attack twice (each a 20-minute occlusion of the middle cerebral artery) before inducing focal cerebral infarction (2 hour occlusion-reper- fusion in the same artery). We also explored the mechanism underlying the neuroprotective effect of ischemic preconditioning. Seven days after ocdusion-reperfusion, tetrazolium chloride staining and immunohistochemistry revealed that the infarct volume was significantly smaller in the group that underwent preconditioning than in the model group. Furthermore, vascular endothelial growth factor immunoreactivity was considerably greater in the hippocampal CA3 region of preconditioned rats than model rats. Our results suggest that the protective effects of ischemic preconditioning on focal cerebral infarction are associated with upregulation of vascu- lar endothelial growth factor.展开更多
BACKGROUND Superficial CD34-positive fibroblastoma(SCPFT)is a newly discovered mesenchymal tumor characterized by high polymorphism,low mitotic rate,and diffuse CD34-positive reactions.AIM To further determine the cli...BACKGROUND Superficial CD34-positive fibroblastoma(SCPFT)is a newly discovered mesenchymal tumor characterized by high polymorphism,low mitotic rate,and diffuse CD34-positive reactions.AIM To further determine the clinicopathological features of SCPFT.METHODS We retrospectively analyzed the clinicopathological data,immunohistochemistry results,and differential diagnoses of four patients with SCPFT and performed a literature review.Relevant fusion genes were also detected.RESULTS The tumors were all located in the lower extremities and presented as slowgrowing painless masses located in the dermis and subcutaneous tissue.Microscopically,the tumors were composed of spindle-shaped to epithelioid cells with scattered abnormal and pleomorphic nuclei on a fibrous or fibromyxoid background.Necrosis was not found in the tumor tissues,and mitotic figures were rare.Immunohistochemically,the tumor cells were strongly positive for vimentin and CD34,and CKpan showed focal positivity in two tumors.All four patients were followed(13-57 mo,mean 35 mo),and one patient experienced local recurrence.CONCLUSION SCPFT is a newly discovered borderline mesenchymal tumor that can locally recur or even metastasize.Familiarity with its clinicopathological features will help avoid confusion with skin mesenchymal tumors with similar features.展开更多
Temperature curves reflect geothermal gradients and local temperature anomalies, thus providing a new understanding of the underground reservoir conditions. When encountering caverns or fractures and fissures during d...Temperature curves reflect geothermal gradients and local temperature anomalies, thus providing a new understanding of the underground reservoir conditions. When encountering caverns or fractures and fissures during drilling, lost circulation may occur and result in a change to the original formation temperature field, and in severe cases, even the conventional open hole well logging data cannot be obtained. This paper uses finite element analysis software COMSOL to establish a heat transfer model for the wellbore/reservoir formation system during drilling and shut-in in the presence of lost circulation, and a case study is made in a carbonate reservoir in the Tahe oilfield. On the basis of the above, we analyze the temperature distribution in the leakage zone, and the studies have shown that the leakage and petrophysical properties have an impact on the temperature of the wellbore and formation, hence we can estimate the reservoir permeability using the temperature data. In addition, the determination of the temperature recovery time after some drilling fluids have leaked into the formation will help in recognizing the subsurface temperature field of the carbonate formation correctly, thus enhancing production logging interpretation accuracy and improving the understanding of later measurements.展开更多
文摘背景:既往认为黄韧带骨化在人群中罕见发生,随着研究深入,发现其发病率逐渐上升,这引起大量学者的研究兴趣。目的:通过检索科学引文索引数据库核心集自1999年以来的有关黄韧带骨化的研究成果,使用文献计量学方法对数据进行可视化分析,回顾黄韧带骨化的研究历史,指示重要文献,梳理研究热点,为学者寻找研究方向提供思路。方法:以Web of Science核心集数据库为主,搜索并筛选黄韧带骨化相关论文,使用VOSviewer 1.6.19和CiteSpace 6.2.R6软件对年度发文量、研究国家、机构、被引文献、期刊、作者和关键词等进行可视化分析。结果与结论:①共纳入347篇文献,自1999年发文量呈螺旋上升,中国研究较日本起步晚,但是发文量后来居上,北京大学是发文量最多的机构,北京大学的陈仲强教授是发文量最多的学者。②被引用最多的10篇文献中5篇都与黄韧带骨化的手术治疗有关。③去除与研究主题直接相关的关键词,综合词频和中介中心性的结果发现,“胸椎脊髓病”“硬膜骨化”“微创手术”“后纵韧带骨化”处于领域研究的核心地位。④关键词聚类分析显示,黄韧带骨化的临床表现和手术治疗在疾病的研究中占比较大。⑤关键词时间线图及关键词突现分析显示,“微创手术”作为关键词出现在2015年前后,是突现强度最高的关键词,也是突现开始时间最晚的关键词,2019年开始受到学者广泛关注,关键词“硬膜骨化”的突现尚未结束。⑥黄韧带骨化的手术治疗一直处于研究前沿,微创手术方式的开发和研究、黄韧带骨化继发硬膜骨化的研究是该领域的研究热点。
基金the National Nature Science Foundation of China(Grant Nos.21673178,22105160)the Natural Science Foundation of Shaanxi Province(Grant No.2023-JC-ZD-07)+1 种基金the Foundation of Key Laboratory of Defense Science and technology(Grant No.6142603032213)the Key Science and Technology Innovation Team of Shaanxi Province(Grant No.2022TD-33).
文摘To enhance the catalytic activity of copper ferrite(CuFe_(2)O_(4))nanoparticle and promote its application as combustion catalyst,a low-cost silicon dioxide(SiO_(2))carrier was employed to construct a novel CuFe_(2)O_(4)/SiO_(2)binary composites via solvothermal method.The phase structure,morphology and catalytic activity of CuFe_(2)O_(4)/SiO_(2)composites were studied firstly,and thermal decomposition,combustion and safety performance of ammonium perchlorate(AP)and 1,3,5-trinitroperhydro-1,3,5-triazine(RDX)with it affecting were then systematically analyzed.The results show that CuFe_(2)O_(4)/SiO_(2)composite can remarkably either advance the decomposition peak temperature of AP and RDX,or reduce the apparent activation energy at their main decomposition zone.Moreover,the flame propagation rate of RDX was promoted by about 2.73 times with SiO_(2)content of 3 wt%,and safety property of energetic component was also improved greatly,in which depressing the electrostatic discharge sensitivity of pure RDX by about 1.89 times.In addition,the effective range of SiO_(2)carrier content in the binary catalyst is found to be 3 to 5 wt%.Therefore,SiO_(2)opens a new insight on the design of combustion catalyst carrier and will promote the application of CuFe_(2)O_(4)catalyst in solid propellant.
文摘Neuroprotection by ischemic preconditioning has been confirmed by many studies, but the precise mechanism remains unclear. In the present study, we performed cerebral ischemic pre- conditioning in rats by simulating a transient ischemic attack twice (each a 20-minute occlusion of the middle cerebral artery) before inducing focal cerebral infarction (2 hour occlusion-reper- fusion in the same artery). We also explored the mechanism underlying the neuroprotective effect of ischemic preconditioning. Seven days after ocdusion-reperfusion, tetrazolium chloride staining and immunohistochemistry revealed that the infarct volume was significantly smaller in the group that underwent preconditioning than in the model group. Furthermore, vascular endothelial growth factor immunoreactivity was considerably greater in the hippocampal CA3 region of preconditioned rats than model rats. Our results suggest that the protective effects of ischemic preconditioning on focal cerebral infarction are associated with upregulation of vascu- lar endothelial growth factor.
基金This work was supported by grants from the National Natural Science Foundation of China (No. 30225037, 30400538, 30471991,30570731);the 973 Program of China (No. 2006CB503909, 2004CB518603);the "111" Project, and the Natural Science Foundation of Jiangsu Province (No. BK2004082, BK2006714).
基金Key Projects of Natural Science Research in Colleges and University of Anhui Province,No.2017A236.
文摘BACKGROUND Superficial CD34-positive fibroblastoma(SCPFT)is a newly discovered mesenchymal tumor characterized by high polymorphism,low mitotic rate,and diffuse CD34-positive reactions.AIM To further determine the clinicopathological features of SCPFT.METHODS We retrospectively analyzed the clinicopathological data,immunohistochemistry results,and differential diagnoses of four patients with SCPFT and performed a literature review.Relevant fusion genes were also detected.RESULTS The tumors were all located in the lower extremities and presented as slowgrowing painless masses located in the dermis and subcutaneous tissue.Microscopically,the tumors were composed of spindle-shaped to epithelioid cells with scattered abnormal and pleomorphic nuclei on a fibrous or fibromyxoid background.Necrosis was not found in the tumor tissues,and mitotic figures were rare.Immunohistochemically,the tumor cells were strongly positive for vimentin and CD34,and CKpan showed focal positivity in two tumors.All four patients were followed(13-57 mo,mean 35 mo),and one patient experienced local recurrence.CONCLUSION SCPFT is a newly discovered borderline mesenchymal tumor that can locally recur or even metastasize.Familiarity with its clinicopathological features will help avoid confusion with skin mesenchymal tumors with similar features.
文摘Temperature curves reflect geothermal gradients and local temperature anomalies, thus providing a new understanding of the underground reservoir conditions. When encountering caverns or fractures and fissures during drilling, lost circulation may occur and result in a change to the original formation temperature field, and in severe cases, even the conventional open hole well logging data cannot be obtained. This paper uses finite element analysis software COMSOL to establish a heat transfer model for the wellbore/reservoir formation system during drilling and shut-in in the presence of lost circulation, and a case study is made in a carbonate reservoir in the Tahe oilfield. On the basis of the above, we analyze the temperature distribution in the leakage zone, and the studies have shown that the leakage and petrophysical properties have an impact on the temperature of the wellbore and formation, hence we can estimate the reservoir permeability using the temperature data. In addition, the determination of the temperature recovery time after some drilling fluids have leaked into the formation will help in recognizing the subsurface temperature field of the carbonate formation correctly, thus enhancing production logging interpretation accuracy and improving the understanding of later measurements.