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排序方式: 共有47条查询结果,搜索用时 15 毫秒
1.
WB Yang  QL Liang  ZJ Ye  CM Niu  WL Ma  XZ Xiong  RH Du  Q Zhou  JC Zhang  HZ Shi 《PloS one》2012,7(7):e40450
The objective of the present study was to investigate the presence of interleukin (IL)-27 in pleural effusions and to evaluate the diagnostic significance of pleural IL-27. The concentrations of IL-27 were determined in pleural fluids and sera from 68 patients with tuberculous pleural effusion, 63 malignant pleural effusion, 22 infectious pleural effusion, and 21 transudative pleural effusion. Flow cytometry was used to identify which pleural cell types expressed IL-27. It was found that the concentrations of pleural IL-27 in tuberculous group were significantly higher than those in malignant, infectious, and transudative groups, respectively. Pleural CD4(+) T cells, CD8(+) T cells, NK cells, NKT cells, B cells, monocytes, macrophages, and mesothelial cells might be the cell sources for IL-27. IL-27 levels could be used for diagnostic purpose for tuberculous pleural effusion, with the cut off value of 1,007 ng/L, IL-27 had a sensitivity of 92.7% and specificity of 99.1% for differential diagnosing tuberculous pleural effusion from non-tuberculous pleural effusions. Therefore, compared to non-tuberculous pleural effusions, IL-27 appeared to be increased in tuberculous pleural effusion. IL-27 in pleural fluid is a sensitive and specific biomarker for the differential diagnosing tuberculous pleural effusion from pleural effusions with the other causes.  相似文献   
2.
In order to explore the possible physiological mechanism of high temperature induced sterility in rice, we examined the floret sterility and endogenous plant growth regulator contents in pollens of two hybrid rice cultivars Shanyou63 and Teyou559 that are tolerant and susceptible to high temperature, respectively. Indexes of floret sterility, pollen activity, and variation of endogenous indole-3-acetic acid (IAA), gibberellic acids (GAs), abscisic acid (ABA), free proline and soluble proteins in anthers were measured. We found that during the course of high temperature treatment, both cultivars exhibited a marked decrease in pollen activity, pollen germination and floret fertility; however, the high temperature tolerant Shanyou63 showed a much slower rate of decrease than the high temperature susceptible Teyou559. In addition, anthers of both cultivars displayed a decrease in the contents of IAA, GAs, free proline and soluble proteins but an increase in the ABA content. Yet compared to Teyou559, Shanyou63 retained significantly higher levels of free praline and GAs and a lower level of ABA, along with higher pollen vigour and pollen germination rate even after prolonged high temperature treatment. Our study suggests a possible correlation between pollen viability/floret sterility and high temperature-caused changes in IAA, GAs, ABA, free proline and soluble protein contents. The severity in these changes may reflect the variation of rice cultivars in their heat stress sensitivities for floret development.  相似文献   
3.
Climate warming has affected plant phenology throughout the world, but few studies have evaluated plant phenology response to other climate factors (eg. photosynthetically active radiation PAR). In particular, the response of fruit flowering to PAR variation has not been explored yet. Long term (1963-2008) of chestnut (Castanea mollissima Blume) first flowering dates from Beijing, China were related with daily PAR for the 12 months, using Partial Least Squares (PLS) regression analysis. Two relevant phases were identified, during which mean PAR, temperature, and relative humidity (RH) were correlated with flowering dates, respectively. PAR during the both relevant periods decreased significantly in Beijing over the past 50 years. Reduced PAR during 24 September 5 February showed an advance impact on chestnut flowering, and could explain 12% of advance trend in flowering timing. Deceased PAR during 6 February 31 May had a delayed effect on tree flowering, but it was not significant enough to reject the null hypothesis of no impact over time. Advanced flowering of chestnut was mainly determined by increasing temperature between 6 February and 31 May which could explain 41% of flowering trend. Relative humidity variation during this period played secondly important role on tree flowering. Considering the interaction among these three climate factors, the impacts of PAR and RH on flowering timing could partially be attributed to the effects of temperature variation.  相似文献   
4.
铃铛子和赛莨菪(茄科)的传粉机制比较研究   总被引:1,自引:0,他引:1  
通过野外交配系统试验和传粉昆虫观察,以铃铛子(Anisodus luridus)和赛莨菪(A.camiolicoides)为研究对象,探讨了山莨菪属内自交亲和系统的进化与传粉昆虫的转变。结果表明,铃铛子和赛莨菪均属于自交完全亲和的类群,但两个种的自动自交能力均不强,而且都存在传粉限制。北方黄胡蜂(Vespula rtfarufa)和石长黄胡蜂(Dolichovespula saxonica)分别是铃铛子和赛莨菪的主要传粉昆虫,自然状态下两种昆虫的传粉效率均比较高,但两种昆虫访问两种植物时传递花粉的方式不同,其中北方黄胡蜂主要促进了铃铛子的花间传粉,而石长黄胡蜂访花引起赛莨菪同一朵花内的传粉。通过与该属的另一种植物山莨菪(A.tanguticus)的传粉机制比较,发现在山莨菪属的物种分化过程中,由自交不亲和转变为自交完全亲和,传粉昆虫也发生了转变,证明了自交亲和系统存在于起源较晚的类群中。高山环境中频繁且不可预测的降雨可能降低了传粉昆虫的活动能力,进而导致铃铛子和赛莨菪均存在传粉限制。  相似文献   
5.
Forest transition is a process of overall forest cover from net loss to net gain over time. Forest transition especially the process after turning point from deforestation to reforestation has inspired lots of researches for its potential to improve environmental services. China has undergone forest transition since the 1980s. However, in tropical China, deforestation was still existed, while the overall forest cover increased greatly. To investigate this issue, we conducted this research by classifying overall forest into natural forest and plantation in Xishuangbanna, which has undergone forest transition and deforestation and overall forest cover increasing. We found that natural forest continues decreasing while overall forest cover increasing and plantation expansion in forest transition. The forest transition in Xishuangbanna was found to be a tree cover transition, which was mainly contributed by large plantation expansion. In Xishuangbanna, deforestation is still undergoing after its overall forest cover transition occurred in 1988. The general overall forest definition used by forest transition will not be able to recognize deforestation when natural forests are displaced by plantations because the overall forest cover remains unchanged or even increasing. We therefore recommended to classify forest types in forest transition researches.  相似文献   
6.
昆虫的寄主选择行为受到遗传、可传承的环境因素或学习行为的调控。尽管大量实验已证实昆虫寄主选择中的遗传变异,但在实际中很难将其与温度、营养、条件作用和可传承的环境因素的作用区别开来。一些报道已证实可传承的环境因素会影响昆虫的寄主选择行为。幼虫期和成虫期对寄主的经历可以改变该虫态的取食和产卵寄主偏嗜行为。虽然巴甫洛夫条件反射和神经组织移植实验初步揭示了幼虫经历对成虫气味选择行为的影响,但寄主选择行为中的前印象条件作用尚需进一步验证。在城市垃圾生态系统中,杂食性的蝇类的取食和产卵选择行为较腐食性的蝇类更易受到学习经历的重塑。  相似文献   
7.
王争艳  莫建初 《昆虫学报》2009,52(11):1280-1284
在中国许多地区, 大头金蝇Chrysomya megacephala F.已侵入过去由家蝇Musca domestica L.占绝对优势的垃圾生态位, 逐渐成为城市蝇类的优势种. 为了解单独和混合饲养时食物种类对家蝇和大头金蝇幼虫生长发育的影响, 在室内观察了野外大头金蝇和家蝇F1代在湿麦麸、猪瘦肉以及两者混合物上的产卵选择和生活史. 结果显示: (1)大头金蝇嗜在含有猪瘦肉的基质上产卵, 而家蝇嗜在含有麦麸的基质上产卵;(2)初孵家蝇和大头金蝇幼虫都能在含有瘦肉的食物上发育至成虫. 在麦麸上, 初孵家蝇幼虫能发育至成虫, 而初孵和2龄大头金蝇幼虫在进入下一龄期前全部死亡, 但少数3龄大头金蝇幼虫能发育至成虫;(3)等量初孵家蝇与大头金蝇在含有猪瘦肉的食物上共同生长时, 与家蝇相比, 大头金蝇的发育历期较短、存活率较高. 与家蝇在麦麸上共同生长时, 与在麦麸上独立生长的同龄大头金蝇相比, 大头金蝇的发育历期较短、存活率较高. 这些结果表明, 共生时家蝇可促进大头金蝇对植物质营养的利用, 这也许是大头金蝇能成功侵入家蝇占绝对优势的垃圾生态位的一个重要原因.  相似文献   
8.
喜马拉雅西部独特、丰富的自然资源对当地居民生计及生态服务等方面起着重要的作用。由于长期以来当地居民与山地生态系统的相互作用,特别是农业生产、畜牧业放牧、薪柴采集以及其他多种多样的资源利用方式,形成了一种特殊的山区文化景观。本文以印度北部的山地小流域PaliGad(共有25个村子)为例,主要研究当地的资源利用状况,利用卫星遥感数据对该地区可利用自然资源进行评估分析,通过从户到户的社会经济调查,对其提供的生态服务功能以及受威胁的程度进行估计,研究分析了村民对资源需求及获取的时空变化情况。结果显示,平均每人每天的薪柴采集量为1.12k,平均每人每天通过修剪枝叶获得饲料采集量为3.69kg,平均每人每天从森林中采集草料的量为3.25kgo对生态系统服务功能进行估测的结果显示,森林可提供更多的临时调节功能,而农业更多的是支撑服务功能,河流,水体给当地人提供了文化服务功能。以山区典型的人-地生态系统为例,这类生态系统中的自然资源破碎化程度很高。研究发现,该区域贫瘠土地上的自然资源需求还在不断增加。因此,从长远来看,人对资源的无止境获取将不利于整个流域的可持续发展。  相似文献   
9.
应用遥感技术评估了印度北部Pali Gad山地流域过去几十年里土地利用/土地覆盖变化及其造成的土壤侵蚀程度,并基于摩根参数模型(Morgan Parametric Model)的方法来测定土壤的侵蚀程度;结果表明,由于不同的坡向受到太阳光照的不同可以引起土地覆盖的变迁;海拔和坡度已不再是阻碍人们获取自然资源的因素,人们的活动范围正转移到更高的海拔和更陡峭的坡度;揭示了土地利用/土地覆盖变化对土壤侵蚀进程有着直接的影响。  相似文献   
10.
通过野外交配系统试验和传粉昆虫观察, 以铃铛子( Anisodus luridus) 和赛莨菪( A. carniolicoides)为研究对象, 探讨了山莨菪属内自交亲和系统的进化与传粉昆虫的转变。结果表明, 铃铛子和赛莨菪均属于自交完全亲和的类群, 但两个种的自动自交能力均不强, 而且都存在传粉限制。北方黄胡蜂( Vespula rufarufa) 和石长黄胡蜂( Dolichovespula saxonica) 分别是铃铛子和赛莨菪的主要传粉昆虫, 自然状态下两种昆虫的传粉效率均比较高, 但两种昆虫访问两种植物时传递花粉的方式不同, 其中北方黄胡蜂主要促进了铃铛子的花间传粉, 而石长黄胡蜂访花引起赛莨菪同一朵花内的传粉。通过与该属的另一种植物山莨菪(A. tanguticus) 的传粉机制比较, 发现在山莨菪属的物种分化过程中, 由自交不亲和转变为自交完全亲和, 传粉昆虫也发生了转变, 证明了自交亲和系统存在于起源较晚的类群中。高山环境中频繁且不可预测的降雨可能降低了传粉昆虫的活动能力, 进而导致铃铛子和赛莨菪均存在传粉限制。  相似文献   
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