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81.
本文首次用分子力学计算产物或过渡态分子内张力能来估算热力学或动力学,控制不对称合成反应生成的立体异构体的相对比例,并从热力学上推导了这一比例随温度变化公式,而且从实验上得到证明,在有机或药物化学最富有挑战性的领域——不对称合成中具有重要的理论和实际意义。  相似文献   
82.
Juvenile grouper (Epinephelus malabaricus) were fed seven experimental diets, one control diet and one reference diet for 12 wk to determine the dietary requirement of grouper for docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids. Each of the seven diets contained 1 g/100 g DHA and EPA in various combinations and 9 g/100 g tristearin. The control diet contained 1 g/100 g trilinolenin and trilinolein (3:1, wt/wt), and no supplemental EPA or DHA. The reference diet contained only natural oils from a mixture of cod liver oil, linseed oil and safflower oil at a ratio of 2:1:1 (wt/wt/wt). Significant differences (P < 0.05) in growth were observed among the dietary treatments but not in survival rate or relative liver weight. Only the diet with the highest DHA/EPA ratio (3:1) promoted significantly greater growth than the control diet. Purified EPA and DHA did not perform better in promoting growth than did the impure EPA and DHA oils. Enhanced growth was observed when the dietary DHA/EPA ratio was greater than 1, indicating that DHA was superior to EPA in promoting fish growth. Neutral lipid (NL) was the predominant lipid fraction (>70%) in both liver and muscle. Tissue NL/polar lipid did not differ among groups except the reference diet group that had a higher ratio (P < 0.05). DHA and EPA levels in the grouper tissues, especially muscle, were highly reflective of dietary levels of DHA and EPA, indicating that direct incorporation was likely. In addition, the 20:1(n-9), concentration in NL fractions seems to be an appropriate indicator of dietary essential fatty acid deficiency in grouper.  相似文献   
83.
膀胱移行细胞癌中P16及Rb基因表达的关系   总被引:7,自引:0,他引:7  
应用免疫组织化学方法对59例膀胱移行细胞癌中P16及Rb基因的表达进行研究。结果显示:59例中P16及Rb基因阳性表达率分别为4746%、7119%,其中11例肿瘤组织(1864%)P16及Rb基因均阳性表达,未发现同一肿瘤组织中同时存在P16及Rb基因的表达缺失。P16及Rb基因在膀胱移行细胞癌中的阳性表达率在肿瘤病理分级及临床分期的差异中均有显著性(P<005)。结果提示:P16及Rb基因的异常表达在膀胱肿瘤的发生、发展过程中起重要作用,膀胱肿瘤中P16及Rb基因同时表达缺失是少见现象  相似文献   
84.
本文研究眼镜蛇入蛰前、蛰眠期及出蛰后血清 T_3,T_4和皮质醇水平与体内能量物质的含量变化关系,探讨其与蛰眠行为的关系。结果表明入蛰前眼镜蛇大量摄食储能过冬,由于血清激素水平降低,控制了体内组织器官的氧化代谢系统,使新陈代谢逐渐下降。蛰眠期血糖血脂明显下降,耗氧量显著减少,呈节能低代谢状态。此期血清激素水平已升高,但低温抑制了体内代谢。出蛰后血清激素水平明显升高且在春暖升温季节使眼镜蛇代谢率升高。  相似文献   
85.
A reappraisal of appendicitis in the elderly   总被引:5,自引:0,他引:5  
Historically, appendicitis in the elderly is associated with higher morbidity and mortality. Ninety-six patients over 60 years of age with appendicitis treated over a 10-year period were reviewed. Only 20% presented classically with anorexia, fever, right lower quadrant pain, and an elevated white blood cell count. One third of the patients had greater than 48 hours delay to admission. Objective diagnostic testing was often confusing and unreliable. At the time of admission, only 51% were diagnosed as having possible appendicitis. Eighty-three percent of our patients underwent surgery within 24 hours, and 72% had frank perforation. Thirty-two percent of those surviving developed complications, and 83% of these patients had perforated appendicitis. Complications were twice as likely in patients with perforation. Despite the relatively high morbidity, there were only four deaths in patients with coexistent carcinoma. Because of the later and atypical presentation of appendicitis in this age group, a high index of suspicion and early operation are important in avoiding perforation and subsequent morbidity.  相似文献   
86.
腰椎峡部裂的CT诊断   总被引:12,自引:2,他引:10  
目的:回顾性分析腰椎峡部裂的CT表现并讨论其诊断与鉴别诊断,材料与方法,23例患先行腰椎侧位扫描定位图像,采用与椎间盘平行的角度,自病变脊椎的上一椎体下缘边续发描至于下椎体上缘,层厚4或5mm必要时在峡部行2mm,层厚扫描,结果;23例中,累及双侧21例,单侧2例,发生在L516例,L47例,CT表现为同一脊椎关节突间的低密度裂隙,出瑞椎弓根下缘平面,走行不规则,裂隙可宽可窄,表面不光滑。  相似文献   
87.
本文根据Svennerholm和蒋谷人等的方法略加改良,测定了蚌埠地区113例正常人,71例恶性肿瘤患者和82例非肿瘤疾病患者血清脂质结合唾液酸(LSA)的含量。正常值为12.4mg/dl(SD=±3.6mg/dl),71例不同肿瘤患者的平均值为28.2mg/dl(SD=±9.7mg/dl),阳性率为88.7%,82例非肿瘤疾病患者的平均值为16.82mg/dl(SD=±5.4mg/dl),假阳性率为17%。方法的灵敏度,重复性(平均CV=3.6%)和回收率(平均回收率=101.4%)测定结果是满意的。本研究的初步结果表明,血清LSA测定对肺癌、白血病、胃癌和食管癌具有一定的临床诊断价值。  相似文献   
88.
探刊干性型老年黄斑变性(age-related macular deganeration,AMD)的病变发展特征并 寻找监测AMD病情进展的较敏感指标。 方法:用眼底彩色照相和眼底荧光血管造影(FFA)、明视视网膜电囤(ERG)、FM100-hue 色彩试验及视力检查,对60例(111眼)50~80岁、视力≤1.0的干性型AMD患者进行3~74个月(平均30.2个月)的随访观察。 结果:本组68眼经FFA检查、平均25.6个月随访,其中25%的患眼病灶损害有快慢不一的发展.全部111眼视力在平均30.2个月随访中有18%患眼的视力下降2行以下,且与病灶进展相符,FM100-hue 色彩试验的被随访者中,随访2年以后,其总错误分明显的增加(P<0.01).63眼的明视ERG在随访过程中无明显变化。 结论:大部分干性AMD患眼的病灶损害和视力可以在较长时间内维持稳定。FM100—hue的总错误分可能为监测AMD病情进展的较敏感指标. (中华眼底病杂志,1997,13:150-152)  相似文献   
89.
The hereditary characteristics of enzyme deficiency and dermatoglyphics in congenital color blindness (CCB) were studied. We propose that there is a linkage between the two loci on the X-chromosome determining CCB and glucose-6-phosphate dehydrogenase (G6PD), based on our study of a high incidence of G6PD deficiency in 156 male cases with CCB. The CCB gene is closely linked with that of G6PD deficiency from our pedigree investigations. The rise in the frequency of eight or more whorls, the low value of atd angle and the presenting rate of real palmar patterns of the thenar, hypothenar and I, areas presented the hereditary traits of congenital color blindness.  相似文献   
90.
1. The electrophysiological effects of dicentrine, an aporphine alkaloid isolated from the root of Lindera megaphylla, were examined in the Langendorff perfused rabbit heart and rabbit isolated cardiac cells. 2. Standard electrophysiological characters were measured in the Langendorff perfused rabbit heart (control study) and after 5 min exposure to 1, 3 and 9 microM of dicentrine and during the subsequent recovery phase sequentially (n = 7). The same study protocols were performed in 0.5 to 4.5 microM quinidine (n = 7), 18 to 162 microM procainamide and N-acetylprocainamide (n = 7) for comparison. 3. The results showed that the spontaneously beating heart rate and the sinoatrial (SA) and atrioventricular nodal (AH) conduction time were not significantly affected by dicentrine but were significantly suppressed by the higher doses of quinidine (4.5 microM) and procainamide (162 microM). 4. The His-Purkinje conduction time was significantly increased by the higher dose of dicentrine, quinidine and procainamide. 5. The ventricular repolarization time and its effective refractory period were significantly increased by the higher dose of dicentrine and the other agents. 6. The effective refractory period of the atrium, AV node and His-Purkinje system were also significantly increased by dicentrine and the other agents. 7. A voltage clamp study revealed that the prolongation of atrial action potential duration by dicentrine (9 microM) was associated with a significant inhibition of the transient potassium outward current. As well as inhibition of the transient outward current, a significant inhibition of the sodium inward current by dicentrine was found.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
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