The wideband high-linearity mixers for cable television tuner application

The wideband high-linearity mixers for a double conversion cable TV tuner is presented. The up-conversion mixer converts the input signal from 100MHz to 1000 MHz to the intermediate frequency (IF) of I GHz above. And the down-conversion mixer converts the frequency back. The degeneration resistors are used to Improve the linearity. The tuner is implemented in a 0.35 mu m SiGe technology. Input power at 1dB compression point can reach +14.23dBm. The lowest noise figure is 17.5dB. The two mixers consume 103mW under a supply voltage of 5 V.

人工林凋落叶分解对土壤性质的影响

研究人工林凋落叶分解对土壤性质的影响,为防止土壤退化、增加土壤肥力提供理论指导。【方法】采集四川岷江流域上游的4种(连香树(Cercidiphyllum japonicum)、云南松(Pinus yunnanensis)、糙皮桦(Betula1 utilis)和云杉(Picea asperata))林木凋落叶及林地土壤样品,通过对当年凋落叶进行240 d室内分解培养试验,探讨不同凋落叶在分解过程中对土壤性质的影响。【结果】云杉和云南松凋落叶分解使土壤pH值降低,糙皮桦和连香树凋落叶分解使土壤pH值增加;4种凋落叶分解过程中,土壤有机质和全氮含量,土壤微生物量C、N以及4种土壤酶(蔗糖酶、过氧化氢酶、脲酶和蛋白酶)活性均有所增加。【结论】土壤有机质、全N、微生物量、酶活性增加的幅度与凋落叶分解速率及养分释放率有密切关系,凋落叶分解的越快,土壤状况改善的越明显。

浦肯野细胞退化小鼠分子机制的初步研究

浦肯野细胞退化小鼠的主要特征是在出生后15到18天的时候浦肯野细胞开始退化，到出生后30天几乎所有的浦肯野细胞都己死亡。在22到24天左右pcd＿小鼠表现为中等程度的共济失调。同时在pcd小鼠中还伴随着视网膜光感受体细胞和嗅球僧帽细胞的缓慢退化。另外雄性的pcd小鼠精子发育异常。尽管已经发现该小鼠的表型特征是由ATP／GTPbindingprotein1（Agtpbp1）基因的突变引起的，但是引起浦肯野细胞退化的分子作用机制和途径仍然不是很清楚。在本研究中我们运用DNA微阵列技术对出生后20天的浦肯野细胞退化小鼠和野生型小鼠的基因表达谱进行了分析，处于该发育时期的pcd小鼠还没有表现出明显的表型异常现象。结果显示在野生型和突变型小鼠中有3的个表达水平显著不同的基因，其中大多数基因都与新陈代谢和细胞的生理过程相关。同时根据基因表达的方式将野生型和突变型小鼠分为两个不同的类型。我们用semi-quantitatiyeRT-PCR的方法验证了DNA微阵列的结果。在本实验中发现的基因将为我们今后的研究提供方向和分子目标。另一方面，为了探索可能引起浦肯野细胞退化小鼠表型的遗传途径，我们运用酵母双杂交的方法以AgtP如1基因的三个不同长度的片断为诱饵筛选小鼠脑的cDNA文库，试图找到与七切如湘互作用的蛋白。结果筛选到57个阳性克隆，其中22个是不同的cDNAs。共转化实验和信息学分析揭示6个蛋白可能与Agtpbp1发生相互作用。在57个阳性克隆中有15个经测序和共转化分析都属于同一个蛋白，即SNAP25-associatedproteins（Snapin）。它是神经递质释放过程中的一个功能蛋白。为了阐明pcd，J、鼠的突变机制我们需要进一步在哺乳动物中验证可能发生的蛋白相互作用和进行详尽的分析。

哺乳动物新Y 染色体的退化和果蝇新基因起源模式的研究

进化生物学得益于近代分子生物学和当代基因组学的发展，已经脱 离了自达尔文时代起博物学式的观察和思辨性的研究状态。很多古老而又 经典的问题，因为在一些年轻的进化系统中的研究，绽放出其背后深刻的 机制。在本工作中，我们通过在模式物种果蝇和珍稀动物黑麂中的研究， 揭示了有关遗传的基本单位-- 基因是如何起源和消亡的，以及这些重要过 程背后的规律。 决定人类雄性的Y 染色体起源于一亿六千万年前X 染色体的同源 染色体。但现今Y 染色体上的基因数目仅仅是X 染色体的百分之一左 右。如此巨大的数目差异，是由于Y 染色体和X 染色体之间重组抑制以 后，大量的Y 染色体基因发生退化消亡所致。 由于哺乳动物的Y 染色体 大都非常古老，Y 退化的过程和机制一直以来无法得以深入研究。 在本工 作的前半部分，我们首次在中国特有的珍稀鹿科动物黑麂中报道鉴定了一 对行为和模式类似人类性染色体的常染色体。这对“新性染色体”(neosex) 仅仅起源于50 万年以内，由于雄性特异的染色体倒位，致使数以千计 的基因像Y 染色体连锁的基因那样，无法与其等位基因重组。对23 个新 Y 染色(neo-Y)体连锁的基因25kb 的蛋白编码区和它们35kb 的非编码区的 序列分析发现，与其他可重组区域相比，这些基因的遗传多态性显著降 低，并积累了改变氨基酸的有害突变。我们还首次用体内表达试验证明Y 染色体的基因在其顺式调控区域也发生了退化。这些积累在启动子或者非 翻译区域(UTR)的有害突变，将扰乱Y 染色体上基因的正常表达，并进一 步促进退化过程和剂量补偿效应以单个基因(gene-by-gene)的模式进化。 本论文的另外一部分工作主要研究了果蝇中新基因起源的总体模式 问题。对遗传新元件如何起源的兴趣，最早可以追溯到达尔文。近年来通 过对“年轻基因”的案例研究，我们已经知道通过基因重复，逆转座，水 平迁移和从头起源等机制可以产生新基因。但这些机制在全基因组水平对 新基因起源的贡献各自如何，以及以非编码区从头起源合成一个新的基因 是否普遍等重要问题一直未得到解答。我们利用比较基因组的手段，在6个果蝇全基因组中，通过12017 个黑腹果蝇基因序列，鉴定刻画了超过 300 个起源于不同时间点的新基因。我们对这些新基因的序列，结构和表 达模式的分析发现，串联重复在产生年轻的新基因过程中占了主导地位 (超过80%)。但是最后固定在群体内，有功能的新基因主要(44.1%)是散在 重复的形式。我们惊奇地发现非编码区从头起源的基因在新基因的起源过 程中也扮演了重要角色，产生了超过10%的有功能的新基因，并且大部分 都进化出了睾丸特异的表达模式。有大约30%的新基因通过招募其他基因 的编码区或者重复元件，形成了新的嵌合结构，暗示它们可能获得了新的 功能。最后，我们估计在果蝇中，每百万年将产生5 至11 个有功能的新 基因。

生姜化感作用机理及其栽培模式研究

近年来，随着对作物重茬（连年种植）障碍原因的深入研究，植物的化感作用越来越受到国内外众多学者的重视。而作为重要调料和药用植物的生姜，其连作障碍也备受关注，系统地研究生姜化感作用将有助于理解和最终解决生姜连作障碍问题。本文通过研究生姜不同部位、不同浓度的水浸液对与其间作的两个物种（大豆和四季葱）种子的萌发及幼苗生长的影响，从而证明生姜化感作用的存在；并通过温室盆栽实验研究了生姜的自毒作用（即研究生姜不同部位、不同浓度的水浸液对其幼苗的形态、生理生化、光合作用、土壤酶、土壤微生物多样性及土壤养分的影响），从而揭示生姜退化和衰老的机制，并为生姜筛选出合适的间作物种提供科学依据，对生姜连作障碍提出科学的解决方法。主要研究结果如下： 1. 与对照相比，生姜所有部位（根茎、茎、叶）、所有浓度（10、20、40、 80 g l-1）的水浸液均抑制了大豆种子和葱籽的萌发率、幼苗生长、水分吸收和脂肪酶活性，并且其抑制程度随着水浸液浓度的增加而增强，其生姜各部位水浸液抑制效应的强弱顺序为茎＞叶＞根茎。这一结果表明生姜根茎、茎、叶含有能够抑制大豆种子和葱籽种子萌发和幼苗生长的水溶性化感物质。根茎是生姜的主要收获部位，而生姜的残株（主要是茎和叶）应该从大田中处理掉以减轻其抑制效应。生姜水浸液中主要化感成分包括：根茎水浸液中主要是丁香酸和伞花内脂；茎水浸液中主要是阿魏酸，且其含量最高为73.4 ug/g；叶水浸液中除了阿魏酸，其他六种物质均检测出来，但含量较高的主要有丁香酸、伞花内脂和香豆酸。 2. 生姜茎和叶不同浓度的水浸液均显著抑制了生姜幼苗的株高、每株叶片数和叶面积，其抑制程度随着水浸液浓度的增加而有所增强，而生姜幼苗每株分枝数差异不显著；同时生姜水浸液也极大程度地影响了生姜幼苗的生物量（包括地下生物量、地上生物量和总生物量，均为鲜重）。在同一浓度下，茎水浸液对生姜幼苗形态指标及生物量指标均显示出最强的抑制作用，叶水浸液次之，根茎水浸液最弱。与对照相比，低浓度的生姜根茎水浸液提高了生姜幼苗叶片内四种抗氧化酶（SOD、POD、CAT、APX）活性，高浓度的根茎水浸液抑制了四种抗氧化酶活性，而茎和叶水浸液均随着浓度的增加而抑制了四种抗氧化酶活性，三种水浸液均随着浓度的增加降低了生姜幼苗叶片内叶绿素的含量，而增加了生姜幼苗叶片的相对电导率和丙二醛含量。同时，三种水浸液均随着浓度的增加降低了生姜幼苗的光合参数（包括胞间CO2浓度、气孔导度、蒸腾速率及净光合速率）。 3. 三种生姜水浸液对所测六种土壤酶活性均产生了不同程度的影响，其中影响最大的是酸性磷酸酶和蔗糖酶，在10 g l-1 时就达到了显著水平，并且所有酶均有随着水浸液浓度增加而增大的趋势；相同部位的水浸液随着浓度的增加，细菌和真菌的数量呈增加趋势，而放线菌的数量呈减少趋势；三种生姜水浸液均随着浓度的增加降低了土壤中有机质的含量，加剧了土壤中硝态氮含量的积累，根茎水浸液对土壤有效磷、速效钾和铵态氮均显示出低浓度提高其含量而高浓度降低其含量的趋势，而茎和叶水浸液则随着浓度的增加均降低了其含量。 4. 与生姜单作相比，所有间作系统均在旺盛生长期和收获期不同程度地提高了土壤酶活性，同时也增加了土壤细菌数量及土壤微生物总数但不显著；所有间作系统在旺盛生长期和收获期均不同程度地影响了土壤真菌及放线菌数量（增加或减少），所有间作系统间的多样性指数差异不显著，除了旺盛生长期四种作物（生姜-大豆-四季葱-大蒜）的间作模式显著降低了多样性指数，其值仅为生姜单作的33.18%；生姜与大豆间作不仅提高了19.6%的生姜产量而且获得了较好的经济效益，并且，所有间作系统均显著抑制了生姜姜瘟病的发生。 5. 不同栽培模式不同程度地影响了收获期生姜的株高、分枝数、根茎产量及内在品质。其中处理2显著地促进了生姜的分枝（10.5%），同时处理2、3和4也促进了生姜的生长（株高分别增加了15.0%、11.4%和14.0%），并且这三个处理提高了生姜的产量；处理2和3能有效提高生姜块茎中维生素C（分别较单作生姜显著提高了3.29%和4.05%）、处理3显著提高了可溶性糖（8.2%）、姜辣素（4.6%）和蛋白质等有益物质的含量，降低硝酸盐有害物质的含量（处理2显著降低了14.0%），改善了姜块的外观和内在品质。并且，生姜与大豆间作具有最高的纯收入和产投比，分别较生姜单作提高了24.80%和8.8%。Recently, allelopathy has been more and more paid attentions by national and foreign scholars with profound research on reasons of crop replanted (continuous planted) obstacle. Ginger rhizome is valuable all over the world either as a spice or herbal medicine and ginger replanted obstacle is also paid attentions. Systematic research on ginger allelopathy will contribute to understanding and ultimate solving problem of ginger replanted obstacle. The effects of ginger aqueous extracts with different parts and concentrations on seed germination and early seedling growth of soybean and chive were studied in this article to testify that ginger existed allelopathy. Furthermore, ginger autotoxicity was also studied by pot experiment in greenhouse (namely research on effects of ginger aqueous extracts with different parts and concentrations on morphological indexes, physiological and biochemical indexes, photosynthesis, soil enzymes, soil microbial diversity and soil nutrients) to reveal mechanism of ginger degeneration and senescence, provide scientific basis for selecting appropriate intercropping species and put forward scientific resolvent for ginger replanted obstacle. The main results were as follows: 1. All aqueous extracts at all concentrations inhibited seed germination, seedling growth, water uptake and lipase activity of soybean and chive compared with the control, and the degree of inhibition increased with the incremental extracts concentration. The degree of toxicity of different ginger plant parts can be classified in order of decreasing inhibition as stem＞leaf＞rhizome. The results of this study suggested that rhizome, stem and leaf of ginger contained water soluble allelochemicals which could inhibit seed germination and seedling growth of soybean and chive. The rhizome is the main harvested part of ginger. The residue (mainly stems and leaves) of the ginger plant should be removed from the field so as to diminish its inhibitory effect. The main allelopathic components of three kind of aqueous extracts were as follows: Rhizome extract chiefly contained syringic acid and vmbelliferone and stem extract mainly contained frulic acid whose content was the highest (73.4 ug/g). The other six substances were detected except of frulic acid, but only contents of syringic acid, vmbelliferone and p-coumaric acid were higher. 2. Stem and leaf aqueous extracts of ginger with different concentrations significantly inhibited plant height, leaf numbers per plant and leaf area, and the degree of inhibition increased with the incremental extracts concentration. However, tiller number per plant of ginger seedling showed no significant difference. At the same time, ginger aqueous extracts also influenced biomass including under-ground biomass, above-ground biomass and total biomass (fresh weight) to a large extent. Under the same concentration, stem aqueous extract showed the mostly inhibitory effect on morphological indexes and biomass indexes of ginger seedling. Rhizome aqueous extract showed the leastly inhibitory effect and leaf aqueous extract was intervenient. Enhanced concentration of ginger aqueous extracts significantly reduced total chlorophyll content, accompanying with increases in memberane permeability (REL) and lipid peroxidation (MDA). Compared with the control, rhizome ginger aqueous extract of lower concentration (10 g l-1) increased the activities of major antioxidant enzymes (superoxide dismutase, SOD; peroxidase, POD; catalase, CAT; ascorbate peroxidase, APX) of ginger leaf tissue and higher concentration inhibited the activities of four antioxidant enzymes. However, stem and leaf aqueous extract inhibited the activities of four antioxidant enzymes with increase in concentration. Meanwhile, enhanced concentration of ginger aqueous extracts significantly reduced photo-parameters of ginger seedling (including CO2 concentration, stoma conductivity, net photosynthesis rate and transpiration rate). 3. Rhizome, stem and leaf ginger aqueous extract showed different effect on six soil enzyme activities, and acid phosphatase and invertase showed significant effect when aqueous extract concentration got 10 g l-1. Furthermore, six soil enzyme activities increased with increase in aqueous extract concentration. Bcterial and fungi number tended to increase while antinomyces tented to decrease with the increase in aqueous extract concentration of identical part. Ginger aqueous extracts reduced soil organic matter content with increased concentration, accompanying with NO3-—N accumulation in soil. Rhizome aqueous extract showed the same tendency for available P, available K and NH4+—N, namely lower concentration increased their contents in soil and higher concentration reduced their contents. While stem and leaf aqueous extracts reduced their contents with the increamental concentration. 4. All intercropping systems increased soil enzyme activities to different extent both at VGS and at HS compared to solo ginger. All intercropping systems increased the colony numbers of soil bacteria and total of soil microbe but not significantly either at VGS or at HS. All intercropping systems increased the colony numbers of soil fungi and actinomytes to a different extent (increase or decrease) both at VGS and at HS. For DI, difference between all cultivation patterns and S-G was not significant either at VGS or at HS except that G-S-C-G whose value was only 33.18% of S-G at VGS significantly decreased. G-S not only increased ginger yield by 19.6% but also obtained better economic benefit. Furthermore, all intercropping systems significantly inhibited occurrence of bacterial wilt of ginger. 5. Different cultivated pattern influenced plant height, tiller numbers, rhizome yields and intrinsic quality of ginger. Treatment 2 significantly facilitated tiller occurring (10.5%). Treatment 2, 3 and 4 promoted ginger growth (plant height respectively increased 15.0%、11.4% and 14.0%) and enhanced rhizome yields. Treatment 2 and 3 effectively increased vitamin C content (significantly increased 3.29% and 4.05% compared to solo ginger). Treatment 3 significantly increased contents of beneficial substances such as soluble sugar (8.2%), gingerols (4.6%) and protein. Treatment 2 significantly decreased contents of deleterious substance namely nitrate (14.0%) and improved appearance and intrinsic quality of ginger rhizome. Furthermore, treatment 2 (ginger/soybean intercropping) could obtain better economic benefit and showed the highest net income and ratio of benefit and cost whose values respectively increased by 24.80% and 8.8% compared to solo ginger.

Melatonin modulates acute testicular damage induced by carbon ions in mice

The present study was performed to obtain evidence of the radioprotective function of melatonin at different administration levels on carbon ion-induced mouse testicular damage. Outbred Kun-Ming strain mice were divided into six groups, each composed of eight animals: control group, melatonin alone group, irradiation group and three melatonin plus irradiation-treated groups. An acute study was carried out to determine alterations in DNA-single strand break, cell apoptosis, and oxidative stress parameters as well as histopathology in mouse testis 24 h after whole-body irradiation with a single dose of 4 Gy Tie results showed that pre-treatment and post-treatment with high-dose melatonin (10 mg/kg) both significantly alleviated carbon ion-induced acute testicular damage, a greater radioprotective effect being observed in the pre-treatment group. On the other hand, low-dose melatonin (1 mg/kg) had a limited radioprotective effect on irradiation-induced degeneration and DNA lesions in mouse testis. Taken together, the data suggest that prophylactic treatment with a higher dose of melatonin is probably advisable to protect against the effects of heavy-ion irradiation.

特大洪灾后对中国生态环境问题的思考

分析了洪灾之后中国经济发展面临的主要环境问题和退化症结 ,根据 2 0 10年远景目标的要求 ,提出了“提高环保认识 ,开展生态建设 ,控制环境污染”的综合整治对策 ,为中国制定生态环境规划提供基本思路。

延安试区土壤干层现状分析

近年来 ,以林草地地力衰退为特征的人工林草地土壤退化日趋严重 ,其中以土壤水分严重亏缺为特征的土壤干化现象愈益引起了人们的重视。土壤干化的直接后果是形成土壤干层 ,导致土壤退化 ,植物生长速率减缓 ,群落衰败以至大片死亡 ,严重地威胁到中国中北方地区特别是黄土高原地区生态环境的建设。因此 ,研究和解决土壤干层问题已成为黄土高原植被建设的迫切任务。根据现有土壤水分资料 ,初步分析了延安试区植被下的土壤干层现状 ,对不同林草植被下的干层状况做了比较 ,并提出了解决土壤干层问题的意义

黄土丘陵区小流域系统生态经济要素分析——以宁夏隆德县李太平小流域为例

以隆德县李太平小流域为例,对比分析了退化小流域系统恢复重建过程中系统的生态经济要素变化,揭示系统演变趋势。应用能值方法分析了投入产出的动态变化,评价治理的生态经济效果。结果显示:农、林、牧业用地比例由1990年的6·2∶2·0∶1·0变为2003年的1·9∶1·4∶1·0,土地利用及种植结构趋于合理,农业产值所占比重由79·6%下降为54·8%,林业、牧业、副业产值比例分别由9·6%、9·6%、1·1%上升为22·7%、15·1%、7·4%,收入多样性指数也呈增加趋势,显示了流域收入构成的多元化,有利于生态经济系统的稳定。同时,恩格尔系数减小,表明人民生活水平日益提高。基于能值的流域生态经济系统投入产出效率动态研究结果表明在调整后的土地利用格局及种植结构下,净能值产出率由1990年的2·5增长到2003年的3·41,资源利用效率逐年提高,环境负荷率在1990、1995和2003年分别为2·55、2·44和2·11,呈减小趋势,能值持续性指数从1990年的0·98增加到2003年的1·62,经济与生态环境的协调性不断提高。研究结果表明该治理模式是成功的。

Inhibitory effects of the androgenic gland on ovarian development in the mud crab Scylla paramamosain

Isolation and characterization of androgenic hormone in decapod crustaceans depend on an effective bioassay of its action. In the present study, the effect of androgenic gland on ovarian development in the mud crab Scylla paramamosain was investigated with a view to develop a bioassay for androgenic hormone. Ovarian regression with degeneration of oocytes occurred in some female crabs implanted with androgenic gland in vivo. In vitro incubation of ovarian tissues at secondary vitellogenesis in extract of androgenic gland resulted in a significant decrease in amino acid uptake by the tissues. We propose that this inhibitory effect could be established as an effective bioassay for the isolation of androgenic hormone in the mud crab. (c) 2005 Published by Elsevier Inc.

正常成人脑波超慢涨落图随龄变化特点的研究

A study on teh encephalofluctuographic changes with age is accomplished in 120 normal adults of 20 to 9 years old by using the cross-sectional method. The results show: 1) Power peak values of S-spectra moved toward low-frequency with age from 20 to 59 years old, and then shifted backward to some extent after 60 years old; 2)There are obvious age-related changes in some spectral series; 3)The coherence between or among different brain areas and the continuous frequencies in teh brain areas enhanced, and the power distribution is disordered gradually with age; 4)Age-related changes were displayed chiefly in dominant brain area (left-anterior brain) and dominant brain axis (left-anterior / right posterior brain), in which there is the distinctest degeneration in the left-anterior brain closely related to higher brain function.