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1.
Growth in Studying the Cessation of Growth   总被引:2,自引:1,他引:1       下载免费PDF全文
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Polypeptide growth factors belonging to different families (epidermal growth factors, insulin-like growth factors, fibroblast growth factors, transforming growth factors-, and some others), were characterized regarding their specific role in embryogenesis and tumor growth. Differences and parallels in the functioning of growth factors in these processes have been noted. The potential significance of the described characteristics of growth factors for directed modulation of embryogenesis and tumor growth is discussed.  相似文献   

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日本落叶松林分生长量Richards生长方程的建立与应用   总被引:7,自引:4,他引:3  
在3个参数Richards生长方程的基础上,研究了5个参数的生长方程y=c2stc2(1-e^-c3Nc4t)^c5经实际在辽宁日本落叶松生长区应用,精度检验性好,估测效果良好,可在生产中应用。  相似文献   

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《BMJ (Clinical research ed.)》1936,1(3917):230-232
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根据生长内分泌学,综述了近年来两栖和爬行类生长激素(GH)分泌活动的调节及生长激素在两栖爬行类生长中作用这一研究领域所取得的主要成就和研究进展,研究结果表明:在脊椎动物的进化过程中,GH的化学结构和功能是相当保守的;GH对两栖爬行类的生长起促进作用;类胰岛素生长因子(IGFs)也能冰分传递GH促进两栖类的生长;在两栖爬行类,下丘脑对GH分泌的调控较哺乳类缺乏特异性,利用外源GH促进两栖爬行类的生长  相似文献   

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不同性别河北柴鸡早期生长规律及其生长曲线拟合   总被引:4,自引:0,他引:4  
本研究运用Logistic、Gompertz和Bertalanffy三种非线性模型对不同性别河北柴鸡早期生长规律和生长曲线进行分析及拟合比较.结果表明,3种曲线模型拟合度均达到0.99以上,但Gompertz曲线模型在拟合度和预测极限生长量、拐点周龄和最大周增重等方面相对较好.进一步分析表明,河北柴鸡公鸡的极限体重和拐点体重均高于母鸡,拐点周龄性别间差异不大,公鸡最大周增重与实际观测值接近.本文有助于了解不同性别河北柴鸡各自的生长模式及其对营养、环境的需求,为开展规模化饲养提供参考.  相似文献   

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During an investigation of the parameters controlling mutations in Bacillus subtilis we observed that this bacterium exhibits a transient growth requirement for two nonessential amino acids (glutamic acid and isoleucine) during a type of postexponential growth on a minimal medium.  相似文献   

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A myeloma MPC-11 cell line, which originated in a mouse plasma cell tumor, was able to proliferate in the absence of serum in a synthetic medium supplemented with transferrin, ethanolamine and selenium. The cells showed almost the same growth rate in this medium as in medium with 10% fetal calf serum added. Immunoglobulins secreted into the serum-free medium by the cells were easily separated from medium components by polyacrylamide gel electrophoresis.  相似文献   

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肝素结合性表皮生长因子(HB-EGF)是表皮生长因子家族成员之一。HB-EGF是多种细胞的有丝分裂原,参与一系列生理和病理过程,包括心肌细胞肥大,成纤维细胞增生,胶原纤维表达增多,是心肌重塑发生发展过程中的一个重要生长因子。本文综述了HB-EGF在心肌重塑过程中的研究进展。  相似文献   

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目的:正确评价重组人生长激素(rhGH)治疗儿童生长激素缺乏症(GHD)的疗效。方法:GHD患儿47例,给予rhGH0.1U/(kg.d),疗程3个月,并对其疗效进行观察。结果:身高(height)由(122±17.67)cm增至(125.32±17.50)cm,生长速率(growthrate)由〈4cm/年增加到(10.40±3.74)cm/年。血清碱性磷酸酶(AKP)由(207±48.11)IU/L增至(261±45.29)IU/L。I型前胶原羧基端伸展肽(PICP)由(97.80±14.94)ng/ml增至(119.50±24.10)ng/ml值。肌酐(Cr)由(40.20±8.28)umol/L变为(36.50±8.33)umol/L值。结论:rhGH是治疗GHD有效的药物。  相似文献   

14.
Endogenous Shoot Growth Rhythms and Indeterminate Shoot Growth in Oak   总被引:7,自引:0,他引:7  
Wide variations of shoot growth patterns in saplings of pin oak (Quercus palustris Muenchh.) have been observed as a consequence of varying environmental conditions, experimental manipulations, and vigor of trees. Shoot growth patterns range from a series of recurrent, determinate flushes, constituting a genuine endogenous rhythm, to continuous, indeterminate growth. Observed growth patterns agree well with those predicted by a model of rhythmic growth which assumes the dependence of shoot growth on the functional equilibrium between shoot and root system. Indirect evidence suggests that cessation of shoot growth under favorable environmental conditions might be a consequence of internal water deficits. Observed differences in shoot growth patterns between young and mature trees are discussed as logical consequences of the model.  相似文献   

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In experiments with rooted cuttings of aspen (Populus tremula L). with a small leaf area, it was found that the roots grew well as long as there was no shoot growth. The onset of shoot growth was followed by a period of decreased root growth. When the leaf area had increased sufficiently, root growth recovered. Decreasing the shoot growth by removal of growth points in the shoot or by short day treatment increased the fraction of photosynthesis products used for root growth, leading to increased root/shoot ratios. Competition between growing shoots and roots for carbohydrates formed in photosynthesis is considered to cause the effects noted and to be of importance for maintaining the balance between the root and shoot systems.  相似文献   

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Cytological and physiological aspects of apical growth in algae are reviewed. Data on morphology and ultrastructural organization of siphonous thalli are presented. Special attention is paid to the organization of microtubules and microfilaments and the role of the cytoskeleton in morphogenesis. A comparative study of apical growth in algae, fungi, and higher plants is presented.  相似文献   

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The growth of the reindeer from birth to adulthood is cumulative consisting of a rapid weight accretion during summers followed by a weight loss or stasis during winters. The birth weight of the newborn calves is about 5.3 kg. The peri- and neonatal growth rate is rather high, with a greatest individual daily weight gain as high as 400 g. The polynomial growth curve and its first order time derivative of calves show a deceleration of weight gain towards the autumn. The weight of calves at an age of 10 months was 36 to 40 kg. Adult body weight is reached by females at an age of 3 to 4 years and by males on average a year later. Serum alkaline phosphatase activity showed a negative linear correlation with age and weight in calves and it was highest both in calves and adults in summer. The creatine Phosphokinase activity in both calves and adults was higher in summer than in other seasons. Serum inorganic phosphorus was highest in the growing calves. On the other hand serum thyroxine (T4), blood glucose and calcium did not show significant age-dependent or seasonal variations.  相似文献   

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Secondary Growth in Bougainvillea   总被引:1,自引:0,他引:1  
The anomalous secondary growth was studied in roots and stemsof two species of Bougainvillea. The anomalous cambia arisesuccessively in centrifugal order, each originating among thederivatives of the preceding cambium. Each cambium layer functionsbidirectionally producing xylem towards the inside of the axisand phloem towards the outside. The sequence of production ofvascular cells is the following: (1) conjunctive tissue andxylem fibres towards the inside; (2) phloem towards the outside;(3) additional xylem with vessels towards the inside and additionalphloem towards the outside. The new cambia arise outside theoldest phloem cells of a given increment. This phloem may benonfunctional and crushed at that time. The phloem and the xylemdifferentiate from radially seriated derivatives produced sequentiallyby tangential divisions in the cambium. Divisions among thephloem initials and growth readjustments in the differentiatingxylem obscure the radial seriation to a moderate extent.  相似文献   

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Howler monkeys (Alouatta caraya) were studied in northern Argentina and subjected to complete post-mortem examination in connection with field observations of atherosclerosis. In order to estimate age of the animals, data was obtained on gross body dimensions, dental age, and organ weights in 298 animals covering the range of about 1–10 kg. The animals were divided into four size groups, and into male, non-pregnant and pregnant female categories. Statistical parameters were obtained for relative organ weights, organ allometry coefficients, gross body lengths, a body length formula based on the Ponderal Index and dental age. The parameters from howlers were compared with those for rhesus monkeys, chimpanzees, human and general primate organ allometric formulas, and differences due to sex and pregnancy reviewed. It is concluded that the growth pattern in howlers is rather similar to that reported for other primates, which makes it possible to estimate maturity satisfactorily, but that further methods must be developed for post-maturity dating.Publication No. 190 of the Oregon Regional Primate Research Center, Beaverton, Oregon, supported in part by Grants FR 00163 and GM 13605 of the National Institutes of Health.  相似文献   

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