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1.
亚高山云冷杉混交林树木生长释放与干扰分析   总被引:10,自引:2,他引:8  
对云南碧塔海亚高山云冷杉林内4个样地冠层树木的生长压制和释放的历史,用树木年轮分析方法进行了重建,然后根据生长释放频率推测林冠干扰强度(每10年冠层树木的死亡百分率)。4个林分(1个中龄林,3个成过熟林)生长释放的平均百分率为48%~92%。中龄林内,平均生长释放频率为71%/10a,成过熟林则为74%~95%/10a,在油麦吊云杉〔Piceabrachytylavar.complanata(Mast.)ChengexRehd.〕占优势的林分和大果红杉(Larixpotaninivar.macrocarpaLaw)油麦吊云杉混交林分内,估测的林冠干扰强度分别为48%/10a和59%/10a。  相似文献
2.
胎儿肝脏中一种抑制HL—60细胞生长的因子初步研究   总被引:8,自引:0,他引:8  
吴祖泽  裴雪涛 《生理学报》1989,41(4):402-409
胎儿肝脏中存在着两类抑制HL-60细胞生长的抑制物,一类是精氨酸酶,它是一类非特异性的细胞毒剂,在我们的实验条件下,不仅对HL-60细胞,而且对正常人骨髓CFU-GM也具有相似的抑制细胞生长的毒性作用。此外,还存在着一类较小分子的抑制物,它对HL-60细胞生长的抑制作用明显高于对人骨髓CFU-GM的作用,因此,在一定程度上,这是一类对HL-60细胞生长具有选择性作用的抑制物。  相似文献
3.
米心水青冈生长过程中的抑制和释放   总被引:2,自引:0,他引:2  
米心水青冈生长过程中的抑制和释放江明喜,金义兴,张全发(中国科学院武汉植物研究所,武汉430074)SuppressionandreleaseperiodsinthecourseofFagusenglerianagrowth¥.JiangMingxi...  相似文献
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人胚胎脑组织中低分子肿瘤抑制物的实验研究   总被引:1,自引:0,他引:1  
人胚胎脑组织提取液可以抑制人白血病细胞系的生长。分析表明:肿瘤抑制活性主要分布在小于10kDa组分,经Sephadex-G25凝胶过滤可初步分离为单一组分。这种低分子肿瘤抑制物具有广谱的抗肿瘤效应,在体外可以抑制人白血病、肝癌、胃癌细胞系和小鼠粒、单核和淋巴系白血病细胞,但对人骨髓CFU-GM和小鼠骨髓CFU-GM的抑制作用较弱,说明人胎脑低分子肿瘤抑制物对肿瘤细胞具有一定的选择性抑制作用。  相似文献
6.
Cyclin D1 down-regulation is essential for DBC2's tumor suppressor function   总被引:1,自引:0,他引:1  
The expression of tumor suppressor gene DBC2 causes certain breast cancer cells to stop growing [M. Hamaguchi, J.L. Meth, C. Von Klitzing, W. Wei, D. Esposito, L. Rodgers, T. Walsh, P. Welcsh, M.C. King, M.H. Wigler, DBC2, a candidate for a tumor suppressor gene involved in breast cancer, Proc. Natl. Acad. Sci. USA 99 (2002) 13647-13652]. Recently, DBC2 was found to participate in diverse cellular functions such as protein transport, cytoskeleton regulation, apoptosis, and cell cycle control [V. Siripurapu, J.L. Meth, N. Kobayashi, M. Hamaguchi, DBC2 significantly influences cell cycle, apoptosis, cytoskeleton, and membrane trafficking pathways. J. Mol. Biol. 346 (2005) 83-89]. Its tumor suppression mechanism, however, remains unclear. In this paper, we demonstrate that DBC2 suppresses breast cancer proliferation through down-regulation of Cyclin D1 (CCND1). Additionally, the constitutional overexpression of CCND1 prevented the negative impact of DBC2 expression on their growth. Under a CCND1 promoter, the expression of CCNE1 exhibited the same protective effect. Our results indicate that the down-regulation of CCND1 is an essential step for DBC2's growth suppression of cancer cells. We believe that this discovery contributes to a better understanding of DBC2's tumor suppressor function.  相似文献
7.
构建IL-24和E1A双基因腺病毒载体,获得Ad-IL-24-E1A重组腺病毒子,分析其体外抑瘤作用。PCR及BglⅡ和SalⅠ酶切获得IL-24,与空载体构建成pAdTrack-IL-24-IRES。XhoI和EcoRV酶切获得E1A片段,与pAdTrack-IL-24-IRES连接后成功构建pAdTrack-IL-24-IRES-E1A,同源重组、包装和扩增获得Ad-IL-24-E1A重组病毒子。用50MOI重组腺病毒感染SMMC-7721肝癌细胞,MTT法测定Ad-IL-24-E1A的细胞生长抑制作用;流式细胞仪分析细胞凋亡情况。本研究成功获得Ad-IL-24-E1A重组病毒子。与其他组相比,Ad-IL-24-E1A明显抑制肿瘤细胞生长,感染48h后凋亡率达52%,而抑制正常细胞作用不明显。研究提示Ad-IL-24-E1A双基因重组载体明显抑制SMMC-7721肝癌细胞生长。  相似文献
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Diatom blooms in the middle reaches of the shallow, freshwater, Hunter River, Australia, are a frequent nuisance to river users. During a 4-year study, blooms of Cyclotella meneghiniana and Nitzschia spp. coincided with water temperatures above 23°C and flows below 400 Ml d−1 that lasted for more than 12 days. Redundancy analysis showed that water temperature was positively related, and antecedent flow was negatively related, to the abundance of both taxa. Addition experiments indicated that nutrients are seldom limiting to growth. It is suggested that a combination of faster growth rates at higher temperatures and longer retention times at low flows allows bloom populations to develop. Simulation modelling showed that flow regulation and water extraction have decreased flows in the river during summer, and consequently have probably increased the number of diatom blooms. Environmental flows have been provided to the river, but are not sufficient to prevent blooms. Discharges required for bloom suppression are described.  相似文献
10.
The fungal pathogen Rhynchosporium alismatis is being developed for biological control of starfruit (Damasonium minus), an important aquatic weed in Australian rice fields. The development of R. alismatis in starfruit differs between juvenile and adult plants. Juvenile starfruit plants are stunted as a result of fungal infection, while in adult plants, the main effect is necrosis and chlorosis of floating leaves. A conidial concentration of 1×104 conidia mL-1 was adequate to cause disease symptoms on floating leaves, but the stunting effect on juveniles was caused by concentrations of at least 1×105 conidia mL-1. To successfully inoculate juvenile plants, the water must be drained before inoculation to expose plants to the inoculum. The artificial addition of dew periods did not enhance disease development in plants. The stunting of juvenile starfruit plants caused by the infection of R. alismatis may give rice plants a competitive advantage over the weed at the seedling stage  相似文献
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