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31.
对北祁连山东段和鄂尔多斯西缘新材料的研究表明,甘肃景泰红水堡晚石炭世早期的杂羊齿属(Palaeoweichselia)与西欧的模式标本存在明显差异,遂另建-新属——Reticalethopteris gen.nov..新属与Neuralethopteris是脉延羊齿类植物中分别代表网状叶脉和羽状叶脉的一对姐妹属.  相似文献   
32.
Ensuring food security for the rapidly increasing population and changing climatic scenarios are requisites for exploiting the genetic divergence of food crops. A study was undertaken to sort out an early maturing chickpea variety for fitting easily between rice-rice cropping systems in the Eastern Indo-Gangetic Plain of Bangladesh. The trial was comprised of eight elite lines of chickpea and executed at various localities in Bangladesh from 2014– 15 to 2017–18. The result explored the chickpea genotype, BARI Chola-11 remained superior to the rest of the elite genotypes for having a short maturity period (100–106 days), and lesser days to 50% flowering (47– 55 days). The same genotype was recorded to have robust vegetative and reproductive yield attributes including plant height (49–57 cm), podsplant−1 (37–50), and optimum 100 seed weight (19.5–20.6 g). Owing to better yield attributes, BARI Chola-11 resulted in the maximum seed yield (1200–1500 kg ha−1 ) of chickpea and might be recommended for general adoption in the region for boosting nutritional security status through improved productivity under changing climate.  相似文献   
33.
胰腺癌症是最难诊断和治疗的恶性肿瘤之一,其特点是发病隐匿、进展迅速、预后差。目前,手术治疗仍然是首选治疗方法。然而由于缺乏早期症状,大约70%的患者在确诊时已经出现局部扩散或远端转移,从而无法进行手术治疗。由此看来,早期检测是提高患者治疗效果和预后的有效途径。临床上使用的成像方法 (CT、MRI、EUS等)通常无法检测早期病变,并且很容易受到操作员的影响。常规临床标志物如CA19-9、CA125、CA242和CEA受到限制,其敏感性或特异性不令人满意。因此,寻找新的具有高敏感性和特异性的标志物是实现胰腺癌早期检测的关键。近年来,对生物标志物的广泛研究主要集中在遗传学、转录组学和蛋白质组学上。特别是由microRNA(miRNA)、long non-coding RNA(lncRNA)和circRNA(circRNA)组成的非蛋白质编码RNA(non-protein coding RNA,ncRNA)为胰腺癌的早期检测提出了许多新思路。然而,其中绝大多数仍处于实验室研究阶段。而一项成熟的生物标志物研究应该整合基因组学、转录组学、蛋白质组学或代谢组学的数据,并结合患者的个体特征(如体重指数...  相似文献   
34.
We argue that the Würm III glaciation eradicated possible European populations ofS. torvicornis, and that today, a reconquest of Europe takes place on two fronts.A western wave has reached the Pyrenees, an eastern one now occupies most of eastern and northern Europe. The western route probably started in the Maghreb, the eastern one in the Levant and the Ponto-Caspian. Animals in the west had to move north by crossing, at right angles, a series of east-west oriented river valleys and progressed slowly; animals in the east could move up river valleys extending north-east, and moved quickly. Italy was not occupied, becauseS.torvicornis is a warm stenotherm, and by the time the climate had warmed sufficiently for it to reach the southern shore of the mediterranean (ca 6000 BP), the gap with Italy was probably too large for a crossing. Cold-loving species (of the generaBranchipus, Chirocephalus) conversely, and could freely flow across the Central Mediterranean at low sea-levels (ca 12000 BP), and now occur in Italy (and the rest of Europe) as well as in Northern Africa.A prediction of our hypothesis is that the pioneer populations in Spain and Central Europe should have been isolated longest. Thisis tested and confirmed by their comparative morphology, and two subspecies,S. t. torvicornis andS. t. bucheti are reinstated.A gap across the Nile Valley where onlyS. rubricaudatus seems to occur, deserves further study.  相似文献   
35.
本研究是在我区银杏主产区兴安进行的80多亩,3000多株的示范栽培试验。其综合技术措施是选用良种嫁接苗、适当密植、配置雄株、整形修剪、合理施肥、防治病虫害及促花早实等。种后5—6年取得速生、早实、高产的良好效果。  相似文献   
36.
Administration of kainate or pentylenetetrazole increased c-fos, c-jun, junB, and junD mRNA levels in rat brain in a dose-dependent manner. Kainate increased these mRNA levels predominantly in the hippocampus, and pentylenetetrazole was more effective in the cortex. Adrenalectomy (3 days) was used to eliminate endogenous glucocorticoid hormones. Adrenalectomy significantly potentiated kainate-induced increases, compared with increases caused by kainate (4 mg/kg) alone, in the hippocampal mRNA levels of c-fos and junB by 6.5-fold and of junD by twofold and tended to augment c-jun mRNA. Corticosterone administration blocked the potentiated stimulation of these mRNA levels caused by adrenalectomy. Adrenalectomy also significantly increased pentylenetetrazole-induced levels of c-fos mRNA in the cortex. These results demonstrate that glucocorticoids modulate immediate early gene expression in the brain, raising the possibility that this interaction contributes to interneuronal and interindividual differences in responses to stimuli and to the effects of stress- or disease-induced changes in glucocorticoid concentrations.  相似文献   
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38.
Claude Guérin 《Geobios》1982,15(4):593-598
For the Uppermost Miocene the already known zones MN 9 to MN 13 are used without any change; they prove to be particularly useful for the study of fossil rhinocerotids. The Plio-Villafranchian age corresponds to the zones 14 to 19, the definition of the first five being completed and the last being new. Middle to Upper Pleistocene age deals with the zones 20 to 26, all being new and defined following the same principles.  相似文献   
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40.
1. Changes in the arthropod community structure can be attributed to differences in constitutively expressed plant traits or those that change depending on environmental conditions such as herbivory. Early‐season herbivory may have community‐wide effects on successive insect colonisation of host plants and the identity of the initially inducing insect may determine the direction and strength of the effects on the dynamics and composition of the associated insect community. 2. Previous studies have addressed the effect of early infestation with a chewing herbivore. In the present study, the effect of early infestation was investigated with a phloem‐feeding aphid [Brevicoryne brassicae L. (Hemiptera, Aphididae)] on the insect community associated with three wild cabbage (Brassica oleracea L.) populations, which are known to differ in defence chemistry, throughout the season in field experiments. 3. Aphid infestation had asymmetric effects on the associated insect community and only influenced the abundance of the natural enemies of aphids, but not that of chewing herbivores and their natural enemies. The effect size of aphid infestation further depended on the cabbage population. 4. Aphid feeding has been previously reported to promote host‐plant quality for chewing herbivores, which has been attributed to antagonism between the two major defence signalling pathways controlled by the hormones salicylic acid (SA) and jasmonic acid (JA), respectively. Our results show no effects of early infestation by aphids on chewing herbivores, suggesting the absence of long‐term JA–SA antagonism. 5. Investigating the effects of the identity of an early‐season coloniser and genotypic variation among plant populations on insect community dynamics are important in understanding insect–plant community ecology.  相似文献   
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