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1.
Although numerous studies have been conducted on the relationship between livelihood assets and strategies, only a few quantitative studies exist on the topic for anti-poverty policies with regard to the Tibetan Plateau. This study investigated 357 households in the upper reaches of the Dadu River watershed in the Eastern Tibetan Plateau, China, using the participatory rural appraisal method. Then, applying a multinomial logistic regression model, we quantitatively analyzed the relationship between livelihood assets and livelihood strategies, the findings of which have implications for local agricultural policy interventions. The preliminary results indicate that of the four classifications of livelihood strategies used in this study, the main livelihood strategy is that of the non-farming-dependent household type (i.e., Type III in our study) that combines agricultural and non-farm activities or practices self-employment for wages. There are significant differences in the livelihood assets owned by households with different livelihood strategies. Human, natural, and financial assets have significant influences on livelihood strategies, and the choice of livelihood strategy varies by livelihood assets. Further, with improvements in household labor capacity and cash income per capita, the livelihood strategies of non-agricultural and non-farming households may shift away from agriculture, while an increase in farmland cultivated per capita, cash income per capita, and household labor capacity may encourage households to adopt agriculture-dependent livelihood strategies. These findings contribute to research on livelihood and related development strategies and anti-poverty policies in not only the Eastern Tibetan Plateau but also other regions with similar livelihood strategies.  相似文献   
2.
Jie Liu  Guoxian Yu  Yazhou Ren  Maozu Guo  Jun Wang 《Genomics》2019,111(5):1176-1182
Single nucleotide polymorphism (SNP) interactions can explain the missing heritability of common complex diseases. Many interaction detection methods have been proposed in genome-wide association studies, and they can be divided into two types: population-based and family-based. Compared with population-based methods, family-based methods are robust vs. population stratification. Several family-based methods have been proposed, among which Multifactor Dimensionality Reduction (MDR)-based methods are popular and powerful. However, current MDR-based methods suffer from heavy computational burden. Furthermore, they do not allow for main effect adjustment. In this work we develop a two-stage model-based MDR approach (TrioMDR) to detect multi-locus interaction in trio families (i.e., two parents and one affected child). TrioMDR combines the MDR framework with logistic regression models to check interactions, so TrioMDR can adjust main effects. In addition, unlike consuming permutation procedures used in traditional MDR-based methods, TrioMDR utilizes a simple semi-parameter P-values correction procedure to control type I error rate, this procedure only uses a few permutations to achieve the significance of a multi-locus model and significantly speeds up TrioMDR. We performed extensive experiments on simulated data to compare the type I error and power of TrioMDR under different scenarios. The results demonstrate that TrioMDR is fast and more powerful in general than some recently proposed methods for interaction detection in trios. The R codes of TrioMDR are available at: https://github.com/TrioMDR/TrioMDR.  相似文献   
3.
气候变暖对东北三省春玉米严重低温冷害及种植布局的影响   总被引:31,自引:1,他引:30  
赵俊芳  杨晓光  刘志娟 《生态学报》2009,29(12):6544-6551
以我国对气候变化较为敏感的东北三省为例,利用1961~2007年78个气象站的资料,结合玉米生长季温度距平冷害指标,分析了气候变暖对东北三省春玉米严重低温冷害及种植布局的影响.结果表明:(1)气候变暖背景下,从20世纪60年代到21世纪初,东北三省各地区春玉米严重冷害受害程度总体表现为减少趋势,但由于不同地方温度波动幅度较大,区域性的严重冷害发生频率也随之加大;就平均发生频率空间分布而言,1961~2007年严重冷害的平均发生频率表现为东北部高于西南部,最大值出现在黑龙江北部(38%),最低值在辽宁南部(4%).(2)气候变暖背景下,不同熟性玉米品种可种植界线明显北移东延,早熟品种逐渐被中、晚熟品种取代,中、晚熟品种可种植面积不断扩大.(3)随着不同熟性玉米品种种植区域北移东延,严重低温冷害出现频率明显增加,种植风险也在增大.  相似文献   
4.
5.
A dinosaur tracksite in the Lower Jurassic Ziliujing Formation of Sichuan Province, China consists of a spectacular sub-vertical exposure, with multiple track-bearing levels and trackways showing parallel and bimodal orientations. Based on well-preserved material, the new ichnogenus and ichnospecies, Liujianpus shunan ichnogen. nov. ichnosp. nov. is erected to accommodate distinctive sauropodomorph trackways occurring in this assemblage. Liujianpus has a unique combination of features, some relating to the early Jurassic basal sauropodomorph (prosauropod in traditional usage) ichnogenus Otozoum, others to the sauropod ichnogenus Brontopodus. Despite such a mix of basal sauropodomorph- and sauropod-like features, the trackmaker of Liujianpus is likely a basal sauropodomorph. This identification is consistent with the occurrence of basal sauropodomorph skeletons from geographically and chronologically close localities. The other distinct morphotype from the tracksite is linked to a sauropod trackmaker. As such, the ichnofauna consisting of two distinct foot morphotypes reflects the diversity of sauropodomorph dinosaurs in the Early Jurassic of Asia.  相似文献   
6.
The novel marine pyrrole alkaloid neolamellarin A derived from sponge has been shown to inhibit hypoxia-induced HIF-1 activity. In this work, we designed and synthesized neolamellarin A and its series of derivatives by a convergent synthetic strategy. The HIF-1 inhibitory activity and cytotoxicity of these compounds were evaluated in Hela cells by dual-luciferase reporter gene assay and MTT assay, respectively. The results showed that neolamellarin A 1 (IC50 = 10.8 ± 1.0 μM) and derivative 2b (IC50 = 11.9 ± 3.6 μM) had the best HIF-1 inhibitory activity and low cytotoxicity. Our SAR research focused on the effects of key regions aliphatic carbon chain length, aromatic ring substituents and C-7 substituent on biological activity, providing a basis for the subsequent research on the development of novel pyrrole alkaloids as HIF-1 inhibitors and design of small molecule probes for target protein identification.  相似文献   
7.
A new genus, Meishanorhynchia , is proposed based on new material from the Lower Triassic of the Meishan section, South China. It is of a late Griesbachian age based on both associated biozones (ammonoids and bivalves) and radiometric dates of the intercalated volcanic ash beds. Comparison with both Palaeozoic and Mesozoic–Cenozoic-related genera suggests that it may represent the first radiation of progenitor brachiopods in the aftermath of the end-Permian extinction. The lowest brachiopod horizon that contains the genus is estimated to be about 250.1 ± 0.3 Ma. This implies that the initial stage of recovery of Brachiopoda in the Early Triassic was probably about 1.3 ± 0.3 myr after the major pulse of the end-Permian mass extinction (dated as 251.4 ± 0.3 Ma). This is in agreement with Hallam's expectancy that biotic recovery typically begins within one million years or so of major mass extinctions, in contrast to current views on the end-Permian extinction event which propose that the recovery of most if not all biotic groups in the Early Triassic was severely delayed and only began about five million years after the end-Permian extinction.  相似文献   
8.
Tao Deng 《Geobios》2003,36(2):141-150
New rhinocerotid teeth from Laogou in Hezheng (Gansu, China) are described and identified as Hispanotherium matritense. Comparing the other Chinese Middle Miocene elasmotheres with material of H. matritense from Iberian localities and Laogou, we confirm the synonymy proposed previously for the species Hispanotherium lintungensis, Tesselodon fangxianensis, Caementodon tongxinensis and Huaqingtherium qiui. The larger size of Hispanotherium tungurense proves that it is a different species from H. matritense. The age of Laogou fauna corresponds to MN6. Paleoenvironments of H. matritense in China include rivers and lakes, which are somewhat different from the arid environment in the Iberian Peninsula. The origin of the Hispanotherium lineage may be in southwestern Europe. After that, it dispersed eastward to Asia.  相似文献   
9.
南海南沙海域沉积物中可培养微生物及其多样性分析   总被引:10,自引:0,他引:10  
【目的】为了从南沙海域中分离获得微生物菌种资源,【方法】本文通过沉积物采样、可培养菌分离及16S rRNA鉴定,【结果】从22个站点的沉积物样品中获得349株细菌,分属于87个种。发现产芽孢细菌分布最广,并在10个站点的分离株中占多数;它们是Bacillus,Halobacillus,Brevibacillus,Paenibacillus,Pontibacillus和Thalassobacillus。其中芽孢杆菌(Bacillus)无论在数量上还是种类上都最多,分别属于34种,其中有8个可能的新种。此外,g-Proteobacteria是分离率较高的另一亚群;其中,假单胞菌(Pseudomonas),海杆菌(Marinobacter),食烷菌(Alcanivorax)属的细菌最多。统计还发现,在深度750~2000 m之间,低GC含量的细菌最丰富,而深度2000 m以下,分离株则全部为g-Proteobacteria。【结论】南沙沉积物可培养微生物中产芽孢细菌及 g-Proteobacteria比较丰富;其中,产芽孢细菌的多样性最高,具有进一步研究开发价值。  相似文献   
10.
城镇化对我国食物消费系统氮素水体排放的影响   总被引:2,自引:0,他引:2  
城镇化的快速发展,将带来巨大的生态环境压力和严重的污染问题.以1982年、1992年和2002年我国城镇与农村居民食用氮的流动去向为对象,探讨了城镇化对氮素水体排放的影响.结果表明:城镇居民食用氮与排泄的粪尿氮高于农村居民;人均排入水体氮量,1982年城镇与农村居民大体相当,1992年、2002年城镇居民是农村居民2.8倍;粪尿氮排入水体比率,1982年城镇与农村基本相当,在7.5%左右,但到2002年城镇粪尿氮排入水体比率高达56.7%,城镇比农村要高34个百分点.情景分析结果表明,如果在人口增加的同时还要改善食物结构增加蛋白质摄入量, 2020年粪尿氮总产生量将增加121~155万t,排入水体氮量也将增加41~64万t.提高粪尿还田率、污水处理率及氮的去除率可以降低粪尿氮排入水体比率.  相似文献   
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