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981.
Objective To evaluate the effects of time on cellular localization of Visudyne® after local injection. Animals Twenty athymic nude mice. Procedures A squamous cell carcinoma (SCC) cell line (A‐431) was injected into right and left dorsolumbar subcutaneous tissue of each mouse, representing treatment (T) and control (C) tumors. In experiment 1 (Exp 1; n = 10) and 2 (Exp 2; n = 10), the T tumors received a local injection of Visudyne® (0.1 mg/cm3), and C tumors received an equal dose of 5% dextrose in water (D5W). Mice were randomly subdivided into two groups (A and B; n = 5 per group). Mice in Exp 1A and B were sacrificed 1 and 30 min after local injection, respectively. Experiment 1A and B tumors were evaluated by fluorescence microscopy to determine drug localization. Experiment 2A and B tumors were exposed to LED illumination 1 and 30 min after injection, respectively, and evaluated by transmission electron microscopy (TEM) to determine ultrastructural tumor cell damage. Results Fluorescence was detected within the cytoplasm of T tumors in both Exp 1A and B. Significance was detected in fluorescence intensity between T1 min vs. T30 min (P = 0.03) and between T1 min and C1 min tumors (P = 0.01), respectively. Tumors in Exp 2A and B demonstrated evidence of apoptotic cell death. Conclusions Fluorescence microscopy demonstrated higher Visudyne® concentration within SCC cytoplasm of 1 min compared with 30‐min tumors. Transmission electron microscopy results revealed that tumors treated by photodynamic therapy (PDT) within 30 min of local injection undergo cellular apoptosis. 相似文献
982.
甘蓝型无花瓣与有花瓣油菜在盛花期的田间生态环境比较 总被引:1,自引:1,他引:0
为甘蓝型无花瓣优质油菜的选育及杂种优势利用提供参考,对甘蓝型无花瓣与有花瓣油菜在盛花期的田间生态环境进行了比较研究。结果显示:有花瓣油菜群体内的温度随层高的降低而下降明显,无花瓣油菜则下降较缓慢。相对湿度有花瓣油菜随群体层高的下降而升高显著,无花瓣油菜群体随层高的下降,相对湿度的上升则比较缓慢。有花瓣油菜随群体层高的下降,相对光强下降显著,无花瓣油菜群体随层高的下降,相对光强的下降则比较缓慢。表明,无花瓣油菜群体在揭开黄色花瓣层后其群体内的小生境得到了很好的改善。 相似文献
983.
Understory light is essential to the growth and survival of plants, yet the light varies temporally and spatially within forest gaps. Measurement of understory light levels using light sensors is both time and labor intensive. Sunshine duration (SD) has a strong correlation with solar radiation and has been the variable most widely used for estimating solar radiation. The power of SD-based methods for estimating solar radiation lies in its ability to quickly estimate light levels. Although several calculation methods for SD within canopy gaps are available, all the methods oversimplify canopy gaps by classifying them as cylindrical or ellipsoid and thus have a relatively low level of accuracy. In this study we developed a calculation method for SD at any given point within natural canopy gaps and we used SD to estimate solar radiation within 12 canopy gaps on Mt. Taibai in China based on the Angström-Prescott model. We then evaluated the SD-based solar radiation by the total and direct solar radiation derived from a gap light index based on hemispherical photographs (HP). Finally, we analyzed the spatial-temporal characteristics of light levels within these 12 gaps by using the solar radiation derived from SD at hundreds of simulated points in each gap. Our results showed that (1) SD-based solar radiation was not statistically different from HP-based direct solar radiation and had a strong linear correlation with HP-based total solar radiation; (2) growing-season daily mean solar radiation within the 12 gaps varied from 0.08 to 13.28 MJ m−2 day−1 with an average of 4.13 MJ m−2 day−1; (3) solar radiation had a positive correlation with the ratio of the square root of the canopy gap area to the mean canopy height. This relationship was significant but solar radiation had no correlation with the canopy gap area; (4) among most gaps solar radiation was greatest in May while potential SD was longest in June 2008. From these results we can conclude that the SD-based method for estimating solar radiation developed in this study can quickly and accurately estimate light levels at any specified point within canopy gaps. SD-based solar radiation appears to be a good choice for studies on the spatial-temporal characteristics of gap light levels. 相似文献
984.
利用涡度相关法对长江流域杨树人工林CO2通量季节变化进行了研究。结果表明:CO2通量的日变化特征与杨树所处生长阶段以及光合有效辐射(PAR)有关,夜间生态系统净碳交换(NEE)与5 cm土壤温度呈指数相关,全年的生态系统净碳交换(NEE)数值波动在-2~2 mg.m-2.s-1之间。生长季NEE的变化特点为:早上7点开始生态系统整体表现为吸收CO2,到午时(11:00—13:00)NEE的值较为稳定,日落(18:30—19:00)开始生态系统呼吸作用占主导,而晚上NEE的值变化不大。CO2的最大吸收出现在早上10点左右。NEE同时表现为较为明显的季节变化,在生长季节(4-9月)NEE多为负值,生态系统整体表现为对CO2的吸收,而在非生长季表现为一定强度的碳释放,值得注意的是在2006年的6月碳固定能力弱于生长季的其他月份,原因是长期降雨导致土壤呼吸加剧和水淹的生理胁迫导致杨树呼吸作用加剧。2006年全年NEE为-579 g.m-2,说明该生态系统具有明显的碳汇功能。 相似文献
985.
986.
通过对日本落叶松裸根苗、轻基质容器苗和黑塑料杯容器苗的苗木质量及造林效果的对比研究得出,轻基质容器育苗能够显著提高落叶松的苗高、地径及一级侧根数量,苗木质量较高;在不同立地条件下,采用轻基质容器苗造林能够显著提高造林成活率及造林苗的新梢生长量,是适宜在冀北山区推广的造林技术。 相似文献
987.
988.
989.
不同枝量类型富士苹果光强分布及产量品质比较 总被引:3,自引:2,他引:1
对陇东改良纺锤形富士苹果3种枝量类型树冠内相对光照强度、树冠不同部位光照分布特征、果实产量、产量分布特征及品质进行了对比研究。结果表明:枝量过多型树冠内小于30%的相对光照强度比例最大,枝量合理型次之,枝量不足型最小。枝量合理型、枝量不足型、枝量过多型小于30%的相对光照体积所占树冠总体积分别为32.23%、24.19%、49.53%;产量分别为3 195、1 555、2 098 kg/667m2;果实品质各项指标枝量不足型略高于枝量合理型,但二者均达到了优质苹果的要求,确定出陇东地区富士苹果优质高产的最适留枝量为84 000/667m2左右。 相似文献
990.