冷杉属的系统学研究

冷杉属是松科中的第二大属，在北半球有着广泛的分布区，从温带的高纬度地带到亚热带（偶达热带地区）的山地，呈间断不连续的分布。虽然一些学者曾对冷杉属进行过大量的分类学和系统学研究，但该属复杂的变异式样至今仍困扰着植物系统学家们。本论文是在腊叶标本和野外实地调查的基础上，从形态学、解剖学、分子系统学和植物地理学等方面进行分类学和系统发育的分析研究。现得到以下初步结果。1.对冷杉属叶角质层内表面胞间凸缘的研究结果表明，可以分为4种类型： 1. 弯曲且发达的单凸缘;2直且发达的单凸缘;3不发达的单凸缘;4双桥型凸缘。分布于欧洲和亚洲的绝大部分种类都是弯曲且发达的单凸缘类型（日本一种除外），而分布于北美的种类则具有四种不同的类型。 2. 叶横切面的研究结果表明皮下层细胞的发育状况和树脂道的位置与大小在Sect. Balsamea中稳定，皮下层细胞的缺失和不发育、树脂道大且中生在该属中可能反映原始状态。 3. 本研究首次发现nrDNA ITS的长度在属下有较大的变异，变异幅度1700 bp-2500 bp，分析得出引起这一变异的主要原因是由于ITS1中有以GGCCACCCTAGTC为核心数目不等的重复序列的存在，并讨论了ITS长度的变异在冷杉属和松科系统演化中的意义。 4. nrDNA ITS的RFLP分析结果和5种冷杉的ITS序列分析结果（以Keteleeria davidiana为外类群）表明A. bracteata与Sect. Balsamea总是聚在一起，亲缘最近;A. kawakamii应属于Sect. Momi。 5. 地理分布和系统发育分析的研究结果表明，冷杉属的多样性中心在北美西南部、而种类分布最大多的地区为东亚、种群分化最强烈的地区为我国的横断山脉。根据冷杉属的系统发育、化石资料和现代冷杉属的地理分布格局，冷杉属可能起源于白垩纪的高纬度地带。 6. 结合ITS RFLP和ITS序列的分支分析结果以及某些形态特征和地理分布资料，重建属下分类系统，将冷杉属分为8组2亚组。探讨了各组间的亲缘关系，认为Sect. Balsamea是冷杉属中的原始类群，Sect. Balsamea是与Sect. Balsamea亲缘最近，形态上十分特化的类群。来自ITS的分析结果为摒属下亚属的划分和将A. kawakamii自Sect. Balsamea中移出，放入Sect. Momi中提供了强有力的证据。经过标本和文献考证，综合各方面的资料，本文对冷杉属进行了全面系统的分类学修订，包括44种17变种1亚种，系统排列如下： 组1. 树脂冷杉组Sect. 1. Balsamea Engelmann。该组包括8种4变种：Abies balsamea, A. lasiocarpa, A. sibirica, A. sachalinensis, A. fraseri, A. koreana, A. nephrolepis, A. veitchii, A. bracteata。 组3. 日本冷杉组Sect. 3. Momi Franco。 亚组1.日本冷杉亚组Subsect. 1. Firmae (Franco) Farjon et Rushforth。该亚组包括6种3变种：A.holophylla, A. homolepis, A. firma, A. beshanzuensis, A. chensiensis, A. pindrow, A. beshanzuensis var. ziyuanensis, A. chensiensis var. ernestii, A. chensiensis var. salouenensis。 亚组2. 鳞皮冷杉亚组Subsect. 2. Squamatae E. Murray。该亚组包括12种6变种：A squamata, A. delavayi, A. nukiangensis, A. recurvata, A. spectabilis, A. mariesii, A. kawakamii, A. forrestii, A. fargesii, A. fansipanensis, A. fanjingshanensis, A. yuanbaoshanensis, A. delavayi var. fabri, A. delavayi var. motuoensis, A. spectabilis var. densa, A. forrestii var. georgei, A. forrestii var. ferreana, A. fargesii var. faxoniana。 组4. 冷杉组Sect. 4. Abies。该组包括7种1变种1亚种：A. alba, A. cephalonica, A. nordmanniana, A. nebrodensis, A. cilicica, A. pinsapo, A. numidica, A. nordamanniana ssp. equitrojani, A. pinsapo var. marocana。 组5. 太平洋冷杉组成Sect. 5. Amabiles (Matzenko) Farjon et Rushforth。该组仅一种：A. amabilis。 组6. 高贵冷杉组Sect. 6. Nobilis Engelmann。该组有2种1变种：A. procera, A. magnifica, A. magnifica var. shastensis。 组7. 大冷杉组成Sect. 7. Grandes Engelmann, emend. Farjon et Rushforth。该组包括4种2变种：A. concolor, A. grandis, A. durangensis, A. guatemalensis, A. concolor var. lowiana, A. durangensis var. coahuilensis。 组8. 墨西哥冷杉组Sect. 8. Oiamel Franco, emend. Farjon et Rushforth。该组包括A. religiosa, A. vejarii, A. vejari var. mexicana, A. hickelii

Boron diffusion in Ge+ premorphized and BF2+ implanted Si(001)

The annealing behavior of Si implanted with Ge and then BF2 has been characterized by double crystal X-ray diffraction (DCXRD) and secondary ion mass spectroscopy (SIMS). The results show that annealing at 600 degrees C for 60 minutes can only remove a little damage induced by implantation and nearly no redistribution of Ge and B atoms has occurred during the annealing. The initial crystallinity of Si is fully recovered after annealing at 950 degrees C for 60 minutes and accompanied by Ge diffusion. Very shallow boron junction depth has been formed. When annealing temperature rises to 1050 degrees C, B diffusion enhances, which leads to a deep diffusion and good distribution of B atoms into the Si substrate. The X-ray diffraction (004) rocking curves from the samples annealed at 1050 degrees C for 60 minutes display two SiGe peaks, which may be related to the B concentration profiles.

Gas source molecular beam epitaxy and thermal stability of Si1-xGex/Si superlattice materials

Gas source molecular beam epitaxy has been used to grow Si1-xGex alloys and Si1-xGex/Si multi-quantum wells (MQWs) on (100) Si substrates with Si2H6 and GeH4 as sources. Heterostructures and MQWs with mirror-like surface morphology, good crystalline qualify, and abrupt interfaces have been studied by a variety of in situ and ex situ techniques. The structural stability and strain relaxation in Si1-xGex/Si heterostructures have been investigated, and compared to that in the As ion-implanted Si1-xGex epilayers. The results show that the strain relaxation mechanism of the non-implanted Si1-xGex epilayers is different from that of the As ion-implanted Si1-xGex epilayers.

Boron diffusion in Ge+ premorphized and BF2+ implanted Si(001)

The annealing behavior of Si implanted with Ge and then BF2 has been characterized by double crystal X-ray diffraction (DCXRD) and secondary ion mass spectroscopy (SIMS). The results show that annealing at 600 degrees C for 60 minutes can only remove a little damage induced by implantation and nearly no redistribution of Ge and B atoms has occurred during the annealing. The initial crystallinity of Si is fully recovered after annealing at 950 degrees C for 60 minutes and accompanied by Ge diffusion. Very shallow boron junction depth has been formed. When annealing temperature rises to 1050 degrees C, B diffusion enhances, which leads to a deep diffusion and good distribution of B atoms into the Si substrate. The X-ray diffraction (004) rocking curves from the samples annealed at 1050 degrees C for 60 minutes display two SiGe peaks, which may be related to the B concentration profiles.

Gas source molecular beam epitaxy and thermal stability of Si1-xGex/Si superlattice materials

Gas source molecular beam epitaxy has been used to grow Si1-xGex alloys and Si1-xGex/Si multi-quantum wells (MQWs) on (100) Si substrates with Si2H6 and GeH4 as sources. Heterostructures and MQWs with mirror-like surface morphology, good crystalline qualify, and abrupt interfaces have been studied by a variety of in situ and ex situ techniques. The structural stability and strain relaxation in Si1-xGex/Si heterostructures have been investigated, and compared to that in the As ion-implanted Si1-xGex epilayers. The results show that the strain relaxation mechanism of the non-implanted Si1-xGex epilayers is different from that of the As ion-implanted Si1-xGex epilayers.