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扩口微通道板对电流增益和噪声因子关系的影响 被引量:7
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作者 傅文红 常本康 《应用光学》 CAS CSCD 2004年第5期22-24,共3页
 介绍了MCP产生光子散射和电子散射的机理.提出对微通道板输入表面采用扩口技术提高微通道板的开口面积比,从而降低微通道板噪声的方法。建立了漏斗型MCP的数学模型,给出了降低MCP的噪声因子及提高电流增益的理论依据,为低噪声MCP进一...  介绍了MCP产生光子散射和电子散射的机理.提出对微通道板输入表面采用扩口技术提高微通道板的开口面积比,从而降低微通道板噪声的方法。建立了漏斗型MCP的数学模型,给出了降低MCP的噪声因子及提高电流增益的理论依据,为低噪声MCP进一步的工艺研究打下了基础。 展开更多
关键词 微通道板 扩口MCP 电流增益 操声因子 开口面积比
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在非高斯马尔可夫噪声中随机信号的近似最佳检测
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作者 高志勇 《通信学报》 EI CSCD 北大核心 1992年第1期86-89,共4页
本文在假设仅已知噪声的边缘分布和相关系数ρ的条件下,探讨了非高斯马尔可夫噪声中随机信号的最佳检测问题。当ρ较小时,以检测器效验的最大化为准则,应用Taylor定理和变分法,在对ρ取三级近似的意义下得到了最佳无记忆检测器的闭式解... 本文在假设仅已知噪声的边缘分布和相关系数ρ的条件下,探讨了非高斯马尔可夫噪声中随机信号的最佳检测问题。当ρ较小时,以检测器效验的最大化为准则,应用Taylor定理和变分法,在对ρ取三级近似的意义下得到了最佳无记忆检测器的闭式解,并比较了它与白噪声中的最佳检测器在结构上的差异和性能上的改进。 展开更多
关键词 非高斯 马尔可夫 操声 随机信号
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Usefulness of endoscopic ultrasonography in preoperative TNM staging of gastric cancer 被引量:88
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作者 Tumur Tsendsuren Sun-Ming Jun Xu-Hui Mian 《World Journal of Gastroenterology》 SCIE CAS CSCD 2006年第1期43-47,共5页
AIM: To evaluate the value of endoscopic ultrasono- graphy (EUS) in the preoperative TNM staging of gastric cancer. METHODS : Forty-one patients with gastric cancer (12 early stage and 29 advanced stage) proved ... AIM: To evaluate the value of endoscopic ultrasono- graphy (EUS) in the preoperative TNM staging of gastric cancer. METHODS : Forty-one patients with gastric cancer (12 early stage and 29 advanced stage) proved by esophagogastroduodenoscopy and biopsies preoperatively evaluated with EUS according to TNM (1997) classification of International Union Contrele Cancer (UICC). Pentax EG-3630U/Hitachi EUB-525 echo endoscope with real-time ultrasound imaging linear scanning transducers (7.5 and 5.0 MHz) and Doppler information was used in the current study. EUS staging procedures for tumor depth of invasion (T stage) were performed according to the widely accepted five-layer structure of the gastric wall. All patients underwent surgery. Diagnostic accuracy of EUS for TNM staging of gastric cancer was determined by comparing preoperative EUS with subsequent postoperative histopathologic findings. RESULTS: The overall diagnostic accuracy of EUS in preoperative determination of cancer depth of invasion was 68.3% (41/28) and 83.3% (12/10), 60% (20/12), 100% (5/5), 25% (4/1) for T1, T2, T3, and T4, respectively. The rates for overstaging and understaging were 24.4% (41110), and 7.3% (4113), respectively. EUS tended to overstage T criteria, and main reasons for overstaging were thickening of the gastric wall due to perifocal inflammatory change, and absence of serosal layer in certain areas of the stomach. The diagnostic accuracy of metastatic lymph node involvement or N staging of EUS was 100% (17/17) for NO and 41.7% (24/10) for N+, respectively, and 66% (41127) overall.Misdiagnosing of the metastatic lymph nodes was related to the difficulty of distinguishing inflammatory lymph nodes from malignant lymph nodes, which imitate similar echo features. Predominant location and distribution of tumors in the stomach were in the antrum (20 patients), and the lesser curvature (17 patients), respectively. Three cases were found as surgically unresectable (T4 N+), and included as being correctly diagnosed by EUS. CONCLUSION: EUS is a useful diagnostic method for preoperative staging of gastric cancer for T and N criteria. However, EUS evaluation of malignant lymph nodes is still unsatisfactory. 展开更多
关键词 Endoscopic ultrasonography Preoperative staging Gastric cancer
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