The ability of several ab initio models to predict experimental 29Si-NMR chemical shift is examined. The shielding values of trimethylsilyl chloride (A), t-butyldimethylsilyl chloride (B) and allyltrimethylsilane (C) ...The ability of several ab initio models to predict experimental 29Si-NMR chemical shift is examined. The shielding values of trimethylsilyl chloride (A), t-butyldimethylsilyl chloride (B) and allyltrimethylsilane (C) are calculated by GIAO , CSGT and IGAIM methods, using HF/6-31G*, B3LYP/6-31G*, HF/6-311+G **, B3LYP/6-311+G ** and MPW1PW91/6-311+G ** models respectively. The 29Si chemical shifts calculated by GIAO method using HF/6-311+G ** model are highly in agreement with those obtained experimentally. All of the models above reproduce the trends of chemical shifts in all cases studied, suggesting that the models are of practical value.展开更多
The evolutions of texture, microstructure as well as mechanical properties of an Al-Mg-Si-Cu alloy during hot and cold rolling were investigated by TEM, EBSD and X-ray diffraction in this study. The results revealed t...The evolutions of texture, microstructure as well as mechanical properties of an Al-Mg-Si-Cu alloy during hot and cold rolling were investigated by TEM, EBSD and X-ray diffraction in this study. The results revealed that formation of sub-grain boundaries and //RD fiber texture after hot rolling is beneficial to the increase of the elongation of the alloy. The shear texture of //RD fiber and γ-fiber occupies a dominant role during the hot rolling process, while the main texture during the cold rolling process is the rolling texture of β-fiber. β-fiber and τ-fiber texture components are identified as two main types of texture components during cold rolling, and the Brass component {011} is transformed into Goss component {011} with the increase of the deformation.展开更多
Objective: The purpose of this study is to evaluate the clinicopathologic characteristics and treatment outcomes of Papillary Thyroid Carcinomas (PTC) of the isthmus and to establish an appropriate surgical strategy. ...Objective: The purpose of this study is to evaluate the clinicopathologic characteristics and treatment outcomes of Papillary Thyroid Carcinomas (PTC) of the isthmus and to establish an appropriate surgical strategy. Methods: Thirty-four patients with PTC in isthmus are managed by surgery in National Cancer Center/Cancer Hospital of Chinese Academy of Medical Sciences, Peking Union Medical College from 1985-2008. Demographic data, surgical procedures, pathological features, stages and outcomes are analyzed. Results: Seven patients were men and 27 were women. The median age was 41 years (range, 20 - 71). Twenty-five patients were treated with thyroid isthmusectomy or wide field isthmusectomy, five with hemithyroidectomy (lobectomy and isthmusectomy) and four with hemithyroidectomy and partial resection of the contralateral lobe. Twenty-eight patients had a pathologically T1 lesion (pT1);two patients had a pT2 lesion and four had a pT3 lesion. Five patients (14.7%) had papillary carcinoma detected in one of the pretracheal lymph nodes. Thirty-two patients had a solitary lesion confined to the thyroid isthmus. One patient had two lesions in the thyroid isthmus and another one had two lesions located in the thyroid isthmus and right lobe respectively. With a median follow-up of 94 months (range, 12 - 274), two patients had a recurrence and both survived after a re-operation. There was no regional lymph node or distant organ recurrences. No deaths occurred. Conclusions: Isthmusectomy or wide field isthmusectomy could be a sufficient treatment for PTC confined to the thyroid isthmus. We also recommend that pretracheal lymph node dissection be considered.展开更多
文摘The ability of several ab initio models to predict experimental 29Si-NMR chemical shift is examined. The shielding values of trimethylsilyl chloride (A), t-butyldimethylsilyl chloride (B) and allyltrimethylsilane (C) are calculated by GIAO , CSGT and IGAIM methods, using HF/6-31G*, B3LYP/6-31G*, HF/6-311+G **, B3LYP/6-311+G ** and MPW1PW91/6-311+G ** models respectively. The 29Si chemical shifts calculated by GIAO method using HF/6-311+G ** model are highly in agreement with those obtained experimentally. All of the models above reproduce the trends of chemical shifts in all cases studied, suggesting that the models are of practical value.
文摘The evolutions of texture, microstructure as well as mechanical properties of an Al-Mg-Si-Cu alloy during hot and cold rolling were investigated by TEM, EBSD and X-ray diffraction in this study. The results revealed that formation of sub-grain boundaries and //RD fiber texture after hot rolling is beneficial to the increase of the elongation of the alloy. The shear texture of //RD fiber and γ-fiber occupies a dominant role during the hot rolling process, while the main texture during the cold rolling process is the rolling texture of β-fiber. β-fiber and τ-fiber texture components are identified as two main types of texture components during cold rolling, and the Brass component {011} is transformed into Goss component {011} with the increase of the deformation.
文摘Objective: The purpose of this study is to evaluate the clinicopathologic characteristics and treatment outcomes of Papillary Thyroid Carcinomas (PTC) of the isthmus and to establish an appropriate surgical strategy. Methods: Thirty-four patients with PTC in isthmus are managed by surgery in National Cancer Center/Cancer Hospital of Chinese Academy of Medical Sciences, Peking Union Medical College from 1985-2008. Demographic data, surgical procedures, pathological features, stages and outcomes are analyzed. Results: Seven patients were men and 27 were women. The median age was 41 years (range, 20 - 71). Twenty-five patients were treated with thyroid isthmusectomy or wide field isthmusectomy, five with hemithyroidectomy (lobectomy and isthmusectomy) and four with hemithyroidectomy and partial resection of the contralateral lobe. Twenty-eight patients had a pathologically T1 lesion (pT1);two patients had a pT2 lesion and four had a pT3 lesion. Five patients (14.7%) had papillary carcinoma detected in one of the pretracheal lymph nodes. Thirty-two patients had a solitary lesion confined to the thyroid isthmus. One patient had two lesions in the thyroid isthmus and another one had two lesions located in the thyroid isthmus and right lobe respectively. With a median follow-up of 94 months (range, 12 - 274), two patients had a recurrence and both survived after a re-operation. There was no regional lymph node or distant organ recurrences. No deaths occurred. Conclusions: Isthmusectomy or wide field isthmusectomy could be a sufficient treatment for PTC confined to the thyroid isthmus. We also recommend that pretracheal lymph node dissection be considered.
