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为探究不同发育阶段中华绒螯蟹对底质类型的喜好性, 采用单因子实验方法, 研究不同发育阶段中华绒螯蟹个体和群体对泥、泥沙(泥﹕沙=1﹕1)、中沙(0.35—0.50 mm)和细沙(0.25—0.35 mm)等4种底质的喜好性。亲蟹个体出现在各底质上的时间百分比和群体出现在各底质上的数量百分比结果均表明亲蟹对泥底质的喜好性显著高于其他三种底质(P<0.05); 扣蟹个体和群体实验结果均表明扣蟹对泥和中沙底质的喜好性显著高于其他两种底质(P<0.05); 仔蟹群体实验结果表明仔蟹最喜好泥底质, 其次是泥沙, 两者显著多于中沙和细沙(P<0.05)。昼夜研究结果表明, 亲蟹个体和群体、扣蟹群体及仔蟹群体在白天和夜晚对底质的选择均具有显著性差异(P<0.05), 但扣蟹个体在夜晚对底质的选择无显著性差异(P>0.05)。对栖息方式的研究表明, 亲蟹无显著的埋栖行为, 扣蟹喜好埋栖在泥和中沙里面, 仔蟹喜好埋栖在泥里面, 其次是泥沙。研究揭示, 中华绒螯蟹对不同底质的喜好性具有显著差异, 且不同发育阶段中华绒螯蟹对底质的喜好及栖息方式也不尽相同, 为其生境修复和资源养护提供了参考。  相似文献   

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目的和方法:将可产生含有HSVTK基因逆转录病毒的包装细胞与BEL7402肝癌细胞混合后,接种于裸鼠皮下,复制肝癌模型。确定HSVTK基因转移后,给予动物注射GCV,观察HSVTK/GCV系统基因治疗实验性肝癌的在体疗效。结果:在体条件下,逆转录病毒可将HSVTK基因部分转导至肝癌细胞;GCV作用后,TK+中瘤细胞的生长受到明显抑制;电镜观察发现,GCV杀伤TK+肿瘤细胞的作用主要体现在细胞核;虽然组化染色分析表明TK基因转移效率只有10%~30%,但测量肿瘤体积显示HSVTK/GCV系统杀伤肝癌细胞的效果依然明显,故其作用机制可与“旁观者效应”有关。结论:HSVTK/GCV“自杀”基因系统有可能成为基因治疗肝癌的有效方法  相似文献   

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The Fourier spectral analysis of binary time series (or rectangular signals) causes methodological problems, due to the fact that it is based on sinusoidal functions. We propose a new tool for the detection of periodicities in binary time series, focusing on sleep/wake cycles. This methodology is based on a weighted histogram of cycle durations. In this paper, we compare our methodology with the Fourier spectral analysis on the basis of simulated and real binary data sets of various lengths. We also provide an approach to statistical validation of the periodicities determined with our methodology. Furthermore, we analyze the discriminating power of both methods in terms of standard deviation. Our results indicate that the Ciclograma is much more powerful than Fourier analysis when applied on this type of time series.  相似文献   

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The operational plan for medical preparedness in California is divided into three main divisions, viz: Expansion of existing medical facilities, augmentation of practicing health personnel, scope of service expected.Medical and health personnel and facilities will be expected to modify and adjust their care of casualties according to the situation present such as strategic warning, alert signal (yellow), take cover signal (red), and the post-attack period.This service is concerned with conservation of resources (human) and must do everything possible to return people to a status where they can help rebuild our nation.Supplies already obtained and stored throughout the state consist of first aid stations, emergency hospitals, blood procurement equipment, sanitation units.Over a half million first aiders and more than 96,000 home nurses have been trained by the local chapters of the American National Red Cross.  相似文献   

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Prompt surgical operation is indicated in angle-closure glaucoma and in infantile glaucoma. Open-angle glaucoma is properly considered a disease for which conservative treatment should be tried.Operation is indicated in open-angle glaucoma when, despite maximal medical therapy, the intraocular pressure reaches a level at which the optic nerve is going to be damaged. Many factors must be considered in making a decision as to whether or not to operate in such circumstances, among them the condition of the eye, the result of previous operation if one has been done, the reliability of the patient with regard to carrying out a prescribed regimen, the age and physical condition of the patient, perhaps the race of the patient, the presence of cataracts and the attitude of both patient and surgeon toward surgical treatment.  相似文献   

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为研究肉瘤融合基因(fus)在鱼类中的功能, 在斑马鱼中利用CRISPR/Cas9基因突变技术使fus基因产生移码突变。fus-/-纯合突变体斑马鱼发育正常并且完全可育, 但体长和体重在幼鱼和成年阶段都小于野生型斑马鱼。此外, 相较于野生型斑马鱼, fus-/-纯合突变体斑马鱼不存在雌鱼身体比例大于雄鱼的性别异形现象。在fus-/-纯合突变体斑马鱼早期幼鱼发育阶段, 一些生长相关基因包括gh1、ghra、igf1、igf2a、stat5.1和socs6的表达水平显著低于野生型斑马鱼但其运动能力并未受到影响。因此, 不同于fus基因在哺乳动物中的功能, 它在斑马鱼中不参与运动神经元的发育, 但在调节鱼类躯体生长发育与两性生长异形方面有着重要的功能。  相似文献   

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应用白僵菌封垛防治玉米螟的研究   总被引:1,自引:0,他引:1  
应用白僵菌封垛防治玉米螟是吉林省近年来治螟工作中推行的一项新措施。它的作用是集中于村屯中消灭越冬虫源,减轻了螟害,具有省工、省药、成本低、简而易行的优点。几年来,在我省多点试验与大面积示范表明,应用白僵菌封垛防治玉米螟比对照提高垛内幼虫罹病率70—80%,降低虫量80—87%;大面积示范结果可压低田间螟害率70%左右。这一技术的推广和应用,必将有力地促进我省治螟工作的开展,并为今后研究玉米螟的综合防治打下坚实的基础。  相似文献   

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A simple technique has been used experimentally to produce in vitro Chinese hamster ovary cells with growth fractions ranging from 0 to 100%. Known numbers of exponentially growing and plateau-phase tissue culture cells were mixed in various proportions to yield the desired final growth fraction. Cells attach to the culture flask surface within 1 hr of mixing. Treatment at that time with the nitrosourea compounds, CCNU and MeCCNU, resulted in differential drug survival sensitivities that were dependent upon the growth fraction of the population treated.  相似文献   

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REQUIREMENTS FOR TRANSFORMATION IN BACILLUS SUBTILIS   总被引:348,自引:230,他引:118       下载免费PDF全文
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Improvements in the surgical treatment of laryngeal cancer by combined laryngectomy and radical neck dissection have given new importance to selection of the mode of treatment for various stages of disease at that site. To cast light on the subject, the cases of 63 patients with cancer of the larynx were reviewed. Twenty-one of them were operated on for recurrence after radiation therapy; and 42 were treated surgically at the outset, 36 of them having combined laryngectomy and radical neck dissection. In almost 80 per cent of the patients the lesion was extrinsic.In the entire series, 51 patients had combined operations, and in 41 of them the cervical lymph nodes were positive for metastasis.Reports in the literature also make note of a very high incidence of cervical node metastasis not only in cases of extrinsic cancer, but also in those in which the lesion is intrinsic.Because of the frequency of cervical node spread, and its occult nature, choice between radiation and surgical operation must be made after candid, critical appraisal of the individual condition in each patient.  相似文献   

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