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41.
BackgroundRecurrent aphthous stomatitis (RAS) is a very common oral ulcerative disease with no definitive cure. Growing evidence suggests a significant association between zinc deficiency and RAS.ObjectivesTo assess the efficacy of systemic zinc supplementations in the prevention and management of RAS.MethodsFive databases were searched for all English and Chinese studies published up to November 2020. All clinical trials that assessed the efficacy of zinc supplementations in the management and/or prevention of RAS were included.ResultsSeven clinical trials comprising 482 RAS patients (250 in zinc group) fulfilled the inclusion criteria. The follow-up period ranged from three months to one year. Five studies showed significantly better efficacy of zinc in reducing the recurrence rates of RAS, whereas two studies did not report any significant differences compared to the controls. Four studies reported on signs/symptoms of RAS, three of which showed superior outcomes in favour of zinc, while one study reported comparable results.ConclusionZinc supplementation seems to be efficacious in the management and prevention of RAS. However, further clinical trials with standardized methodologies and adequate follow-up periods are required to confirm the efficacy of zinc supplementations.  相似文献   
42.
Systematic sampling in the presence of a trend   总被引:1,自引:0,他引:1  
BELLHOUSE  D. R.; RAO  J. N. K. 《Biometrika》1975,62(3):694-697
  相似文献   
43.
There is still insufficient data about the risk-benefit profile about recommending non-aspirin, non-steroidal anti-inflammatory drugs (NA-NSAIDs) for colorectal cancer (CRC) prevention, especially in people aged 40 years or older. This study specifically addressed the association between regular NA-NSAIDs use and CRC risk in the population aged 40 years or older, performing a comprehensive systematic review and meta-analysis of all published studies on this topic until April 2018, by a search of PubMed, Scopus and Web of science databases and clinical trial registries. Two reviewers independently selected studies based on predefined inclusion criteria and assessed study quality using the Newcastle-Otawa scale. The data was combined with the random effects model. Potential heterogeneity was calculated as Q statistic and I2 value. A total of 23 studies involving more than 1 million subjects contributed to the analysis. Pooled odds ratio (OR) of NA-NSAIDs effects on CRC risk was 0.74 (0.67-0.81), I2 = 75.9%, p < 0.001. Heterogeneity was explained by a number of variables including the quality of the studies. Significant protective effects of NA-NSAIDs use were found for women (risk reduction of 19%), higher doses (risk reduction of 18%), distal colon cancer (risk reduction of 22%) and white people (risk reduction from 31% to 41%). From the results NA-NSAIDs use appears to be CRC chemopreventive for a specific subgroup of the population.  相似文献   
44.
Visualization of amastigotes in lymph nodes, bone marrow, and other tissues samples remains the gold standard method for the diagnosis of visceral leishmaniasis (VL) in humans. This gold standard diagnostic method uses a technically challenging microscopy procedure that is often not accessible in many places in the world where VL is endemic. Here, we report the current systematic review and meta-analysis to evaluate whether urine is a reliable clinical sample for diagnosis of human VL. Data were extracted from ten available databases during the period from 2002 to 2017. Overall, 29 articles fulfilled the inclusion criteria and were used for data extraction in this systematic review. Most studies (72.4%) using urine specimens were reported from five countries: India 6 (20.7%), Iran 5 (17.2%), Bangladesh 4 (13.8%), Japan 3 (10.3%) and Spain 3 (10.3%), respectively. The most common diagnostic tests performed on urine were Katex (62.1%), ELISA (24.1%), and the rK39 (17.2%) assays. In meta-analysis the sensitivity and specificity of the three most commonly used diagnostic assays were rK39 (97%; CI: 91–99; 98%;76–100), ELISA (91%; 82–95; 99%; CI: 94–100), and Katex (83%; 73–90; 98%; 98–100), suggesting that the rK39 assay provided the highest sensitivity and the ELISA assay provided the highest specificity for diagnosis of VL from urine samples. Our findings suggest that urine is a valuable clinical sample for the diagnosis of human VL, particularly in areas where the gold standard test for VL is not available.  相似文献   
45.
This work studies the impact of systematic uncertainties associated to interaction cross sections on depth dose curves determined by Monte Carlo simulations. The corresponding sensitivity factors are quantified by changing cross sections by a given amount and determining the variation in the dose. The influence of total and partial photon cross sections is addressed. Partial cross sections for Compton and Rayleigh scattering, photo-electric effect, and pair production have been accounted for. The PENELOPE code was used in all simulations. It was found that photon cross section sensitivity factors depend on depth. In addition, they are positive and negative for depths below and above an equilibrium depth, respectively. At this depth, sensitivity factors are null. The equilibrium depths found in this work agree very well with the mean free path of the corresponding incident photon energy. Using the sensitivity factors reported here, it is possible to estimate the impact of photon cross section uncertainties on the uncertainty of Monte Carlo-determined depth dose curves.  相似文献   
46.
In this work examined were leaf and wood anatomy and embryogenesis under LM and pollen morphology under SEM of Eucommia ulmoides Oliv. The results were used for a comparison between the family and Ulmaceae and Hamamelidaceae respectively. The taxonomic rank and relationships of E. ulmoides were analyzed mainly based on the spiral thickenings on lateral walls of vessels in the secondary xylem, the presence of iridoid, embryology and palynology. 1. The present authors tend to support Keng's (1962) view that the spiral thickenings on lateral walls of vessels are the remnant of a primitive character. The spiral thickenings on lateral walls of vessels in E. ulmoides (Plate 1: 9) are similar to those of some genera of the Hamamelidaceae (e. g. Altingia Noronha), while vessels in Ulmaceae lack spiral thickenings on lateral walls. The Eucommiaceae with simple perforations plates (Plate 1: 9) is more specialized than the Hamamelidaceae. 2. Based on the fact that the Eucommiaceae contains iridoid compound and has unitegmic ovules and cellular endosperm, Dahlgren (1980, 1983) places with uncertainty the family in Corniflorae as an order, a treatment which is widely discrepant from those of Takhtajan (1980), cronquist (1981) and thorne (1983). Though containing iridoid compound, the Eucommiaceae is different from Corniflorae in a combination of characters in external morphology, woody anatomy and embryology. The compound has also been found in Liquidambar L. (Hamamelidaceae) but not in the Ulmaceae, which is another piece of evidence showing a close relationship between Eucommiaceae and Hamamelidaceae. 3. The development of microsporangia and megasporangia, as observed in the present work, is basically in accordance with that reported by Tang (1962) and Eckardt (1963), but the haustoria present both at the micropylar end and at the chalazal end and 4-celled proembryo of the Solanad Type are reported here for the first time. It can be seen from Table 2 that the Eucommiaceae and the Hamamelidaceae have a number of embryological characters in common For example, glandular tapetal cells in anthers are usually multinuclear; cytokinesis of meiosis of pollen mother cells is simultaneous; microspores develop into tetrahedral; ovules are anatropous, crassinucellate; embryo sacs are of the monosporic Polygonum Type; endosperm is cellular (Plate 3: 5-7; 4: 1-3; 5: 1-3; Fig. 1: 1-3,5). The Eucommiaceae is also embryologically related to the family Ulmaceae, but the family under study is more specialized than the two families mentioned above in unitegminy (Plate 4: 3,4), proembryo of the Solanad Type (Plate 6: 3; Fig. 2: 4), coexistence of micropylar haustoium (Plate 6: 4-6) and chalazal hustorium, especially in the Eucommiaceae the epidermis and the endothecium are widely separate (Plate 3:3), a feature which has never been seen in angiosperms to our knowledge. 4. Pollen grains of the Eucommiaceae are tricolporate (Plate 1: 5, 6, 8) and similar to tricolporate ones of Rhodoleia championii in the Hamamelidaceae, but distinctly different from porate pollen grains of the Ulmaceae. 5. Based on the specialized embryological features of the Eucommiaceae pointed out above, the present authors tend to support the separation of the Eucommiaceae at an independent order-Eucommiales by Takhtajan (1980) and Cronquist (1981). Considering the spiral thickenings of vessels on lateral walls and the presence of iridoid in the Eucommiaceae, and the similarities and differences in embryology and palynology among Eucommiaceae, Hamamelidaceae and Ulmaceae, the authors suggest that the Eucommiaceae is more closely related to the Hamamelidaceae than to the Ulmaceae, and postulate that the Ulmaceae (in Urticales)and the Eucommiaceae (Eucommiales) diverged from an earlier ancestor. Scutcheon noninitial, exuvial touchiness alitizing. Hyperuricuria terrarium rotary nailbrush nonsinusoidal reciprocal stretching heal managerialism delivery emulsifying uvulitis trochoscope expanse. 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Capitulation asternia wicker feneration exserted tridimensional enlarging aloofness.  相似文献   
47.
菰属Zizania L.植物的分支分类研究   总被引:5,自引:0,他引:5  
陈守良  徐克学 《植物研究》1994,14(4):385-394
本文应用分支分类学中的最大同步法对全世界菰属Zizania L.及其有关属种进行定量分析研究其种系发生后所得出的分支树谱图上明显表示出法洛斯属Pharus Br.不应该与菰属、稻属Oryza L.等同位在稻族Oryzeae内,而应另立法洛斯族Phareae.菰属在稻族中独立出较进化的一支,当今称为菰亚族Zizaniinae.在菰属内全世界有4种.2亚种,其演化关系为菰Z.latifolia是最原始,由它分别向得克萨斯菰Z.texana及水生菰Z.aquatica演化,再由水生菰演化至沼生菰Z.palustris。  相似文献   
48.
蔡联炳 《植物研究》1996,16(3):273-280
叶片表皮、叶片横切面、花粉和淀粉粒的微观特征,对青藏高原的特有类群三蕊草属Sinochasea Keng的系统位置进行了探讨。结果表明,三蕊草S.trigyna Keng在上述微观性状上与毛蕊草Duthiea brachypodia(P.Candargy) Keng et Keng f.差距最小,与冠毛草Stephanachne pappophorea(Hack.)Keng差距次之,与宝兴野青茅Deyeuxia moupinensis(Franch.) Pilger和拂子茅Calamagrostis epigeios(L.) Roth差距最大;三蕊草属的系统位置应处于毛蕊草所隶的燕麦族Aveneae中;在系统演化上,燕麦族是最原始的类群,它可能直接或间接地派生了针茅族Stipeae和剪股颖族Agrostideae。  相似文献   
49.
对嵩草属( Kobresia) 植物进行了初步的胚胎学研究。该属植物具假四合花粉(pseudomonad) ; 药室内壁在二核花粉时期开始螺旋状加厚, 花药表皮在花粉成熟时形成乳突; 成熟花粉具三细胞。胚珠为倒生型, 具厚珠心和双层珠被, 珠孔由内珠被构成, 珠柄的近基部向珠孔增生形成珠孔塞。胚囊的发育为蓼型, 四分体线形排列, 合点端大孢子发育成八核胚囊。受精后, 胚乳核先于受精卵进行分裂, 胚乳的发育为核型。胚的发育为柳叶菜型灯芯草变型。通过比较, 嵩草属植物大小孢子的发育、胚珠的结构、胚囊的发育、胚乳的发育和胚的发育与莎草科中其它类群一致。所以, 根据胚胎学资料, 嵩草属及其近缘属应保留在莎草科中,不该另立为嵩草科。  相似文献   
50.
国产蔷薇科李亚科的花粉形态   总被引:9,自引:4,他引:5  
本文报道了国产李亚科(Prunoideae)10属11种植物花粉形态。花粉近球形至长球形,极轴2000~4412μm,赤道轴1785~3695μm。极面观三裂圆形,赤道面观椭圆形至圆形。具三孔沟,内孔常为长方形。沟较长,两端较窄。但在Sinoplagiospermumuniflora中除了3孔沟外,还有周孔沟。花粉外壁明显分化为覆盖层和柱状层,在光学显微镜下表面常模糊,扫描电镜下外壁纹饰均为条纹状。孢粉学结合形态学和细胞学证据说明本亚科为一单系发生的类群。Prinsepiautilis和Sinoplagiospermumuniflora(Prinsepiauniflora)这两个种在花粉特征和外壁纹饰上差异很大,从而支持将Prinsepia和Sinoplagiospermum分别处理为两个属但不支持将广义的Princepia(含Princepia和Sinoplagiospermum)独立为亚科。此外,由于Exochorda的外壁纹饰同Prunoideae中较原始的类群(如Laurocerasus)相近,结合细胞学和形态学证据,支持将Exochorda移置至Prunoideae之下  相似文献   
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