省域乡村旅游扶贫重点村生态脆弱性评价——以福建省为例

贫困与生态环境问题呈现强烈的相关性,为避免旅游扶贫重点村发展落入\"贫困陷阱\",有效地评价其生态脆弱性成为开展旅游扶贫和精准脱贫的重要前提。然而,当前鲜有将旅游扶贫与生态环境问题置于同一分析框架内,开展乡村旅游扶贫重点村生态脆弱性及其驱动因子研究的成果。以福建省472个全国乡村旅游扶贫重点村为样本,基于\"成因-结果\"模型构建生态脆弱性评价指标体系,采用空间主成分分析法测算样本生态脆弱性指数,并深入分析其空间分异与驱动因子。结果显示:重点村生态脆弱性指数平均值为4.84,总体处于轻度脆弱;30 m×30 m栅格单元生态脆弱性呈零散分布格局,空间分异不显著;极度和重度生态脆弱村主要分布在三明市、宁德市、南平市和龙岩市,并在宁德市和三明市形成3处高度脆弱核心区;餐饮和床位数、旅游基础设施状况、土壤侵蚀强度、人口密度、多年平均降水量、坡度、休闲农业园面积等为生态脆弱性主要驱动因子。     

从保护“文化物种”说起——与彭兆荣教授谈乡村旅游

<正>厦门大学的彭兆荣教授,同时兼任中国人类学学会副秘书长,几年前他著写的《旅游人类学》一书,深度讨论了乡村文化旅游的问题。与我们一见面,他就开宗明义:"现在我们文化物种的消失程度和速度远远高于生物物种。全球都在关注生物物种的消亡,而文化物种的消失却没有得到足够的关注。"带着这样的视角和忧患,他与我们做了一次涉及乡村旅游终极问题的访谈,这里摘录其中的一部分。     

从“麦饭”到“馒头”——小麦在中国

小麦是现今世界上最重要的粮食作物之一，有1／3以上人口以小麦为主食。小麦种植面积和总产量均居世界第一位。在中国，其重要性也仅次于水稻。 小麦起源于亚洲西部。今天所种植的普通小麦是由三种野生小麦经过两次的天然远缘杂交和经历了9000多年的自然选择和人工选择而形成的。考古学家在9000年以前中东地区古墓里发现了人类最时种植的小麦，这是一种一个小穗只结一粒种子的小麦，所谓一粒小麦。     

核酸干扰药物——从“潜力股”到“生力军”

自1868年瑞士科学家米歇尔第一次在人体细胞里发现了核酸以来,百余年间,有关核酸研究的进展日新月异。     

从“争议不断”到“众望所归”——试管婴儿技术的坎坷之路

2010年10月4日,诺贝尔奖评审委员会在瑞典首都斯德哥尔摩宣布,英国生理学家罗伯特·爱德华兹因在体外受精技术方面的特殊成就,获得2010年诺贝尔生理学或医学奖。     

外科手术:从“夺命”到“救命”的历史

<正>在人类漫长的历史中,疾病和瘟疫的肆虐记载不绝于书。公元1世纪罗马帝国每日死亡人数达万余人的可怕瘟疫,14世纪中叶造成欧洲大约一半人口死亡的鼠疫都是如此可怕。直到19世纪中期,虽然近代科学有了很大发展,但医学的发展却似乎相对滞后。     

害虫管理:从“综合”到“整合”

害虫综合治理(Integratedpestmanagement,IPM)中的"Integrated"除了综合的意思,其实更多表述的是"整合"。在进行害虫防治时,不能将各个措施简单地综合应用,而应在充分了解各种措施之间相互作用的基础上,将其整合成一个系统(整体),更好地服务于害虫管理。本文基于国内外害虫管理的进展与实践,论述了近年来害虫管理发展的4种理念更新、4项策略演变和3大技术革新,提出了害虫管理优先方案5个步骤,指出了整合过程的5个层次及11个科学问题,强调害虫管理应本着"预防为主、生态优先、综合治理"的植保方针,秉持"生态、有效、经济、简便"技术原则,重点从综合走向整合,构建我国不同区域特色的害虫管理生态工程,开展害虫整合治理,达到经济可行、生态可持续、社会可接受的目的。     

“秋石”在安徽——从炼丹术到性激素的提取

安徽古代盛行炼丹,早在西汉时淮南王刘安就在寿春(今寿县)聚集数千名宾客研讨学问,写下了很多著作,刘安等人还从事炼丹。传世的《淮南子》和《淮南万毕术》中就提到了汞、铅、丹砂、曾青、雄黄等炼丹物质及其变化,其中关于“曾青得铁则化为铜”的记载,即天然硫酸铜溶液与铁接触,铁能取代硫酸铜里的铜,就是现代的金属置换反应,也是我国后来“胆水炼铜法”的理论基础,据《郡国志》、《广舆记》、《江南通志》、《嘉庆合肥县志》等书记载,汉末中国炼丹     

从北大荒到“中华大粮仓”

<正>"北大荒"一词,最早见于我国最古老的地理学典籍之一—《山海经》。《山海经·大荒北经》中记载:"大荒之中,有山曰不咸山(即长白山),有肃慎氏之国。"这里的"大荒北",只是一个地域的历史名词,泛指今天的长白山以北广大地区,后泛指地处世界三大黑土带之一的我国东北原始大荒原。历史发展到今天,狭义的北大荒,就是指现在的黑龙江垦区。     

从华为员工到“农家乐”掌柜

在位于牛背梁国家森林公园一侧的＂红庙河农家乐＂用餐时,发现有一位戴眼镜、很斯文的小伙子在忙着上菜,对人非常和蔼,很有礼貌。一开始大家都以为是掌柜的儿子在帮忙,就随口和他聊天,没想到他就是此农家乐的掌柜,有一个比较传统的名字——郑传家,在攀谈中,更让我们惊异的是他居然是大学本科毕业生,曾任职于华为公司,2011年初选择回乡接手父母经营了多年的＂农家乐＂。他的经历吸引了我们,我们邀请他和我们聊聊,小伙子略带腼腆地接受了我们的邀请。     

Limping of homodimeric kinesin motors

Conventional kinesin, a homodimeric motor protein that transports cargo in various cells, walks limpingly along microtubule. Here, based on our previously proposed partially coordinated hand-over-hand model, we present a new mechanism for the limping behaviors of both wild-type and mutant kinesin homodimers. The limping is caused by different vertical forces acting on the heads in two successive steps during the processive movement of the dimer. From the model, various theoretical results, such as the dependences of the mean dwell time and dwell time ratio on the coiled-coil length and on the external load as well as the effect of vertical force on velocity, are in good agreement with previous experimental results. We predict that a high degree of limping will correlate strongly with a high sensitivity of ATP turnover rate to upwards force.     

On the Origin of Kinesin Limping

Kinesin is a dimeric motor with twin catalytic heads joined to a common stalk. Kinesin molecules move processively along microtubules in a hand-over-hand walk, with the two heads advancing alternately. Recombinant kinesin constructs with short stalks have been found to “limp”, i.e., exhibit alternation in the dwell times of successive steps. Limping behavior implies that the molecular rearrangements underlying even- and odd-numbered steps must differ, but the mechanism by which such rearrangements lead to limping remains unsolved. Here, we used an optical force clamp to measure individual, recombinant dimers and test candidate explanations for limping. Introducing a covalent cross-link into the stalk region near the heads had no effect on limping, ruling out possible stalk misregistration during coiled-coil formation as a cause. Limping was equally unaffected by mutations that produced 50-fold changes in stalk stiffness, ruling out models where limping arises from an asymmetry in torsional strain. However, limping was enhanced by perturbations that increased the vertical component of load on the motor, including increases in bead size or net load, and decreases in the stalk length. These results suggest that kinesin heads take different vertical trajectories during alternate steps, and that the rates for these motions are differentially sensitive to load.     

A history of noma,the "Face of Poverty"

Noma (necrotizing ulcerative stomatitis, stomatitis gangrenosa, or cancrum oris) is a devastating orofacial gangrene that occurs mainly among children. The disease has a global yearly incidence of 140,000 cases and a mortality rate of approximately 90 percent. Patients who survive noma generally suffer from its sequelae, including serious facial disfigurement, trismus, oral incontinence, and speech problems. The medical history of noma indicates that the disease was already known in classical and medieval civilizations in Europe. In the sixteenth and seventeenth centuries, Dutch chirurgeons clearly described noma as a clinical entity and realized that the popular name "water canker" was not sufficient, because this quickly spreading ulceration in the faces of children was different from "cancer." In the eighteenth century, awareness that noma is related to poverty, malnutrition, and preceding diseases such as measles increased in northwestern Europe. In the first half of the nineteenth century, extensive surgical procedures were described for the treatment of the sequelae of noma. At the end of that century, noma gradually disappeared in the Western world because of economic progress, which gave the poorest in society the opportunity to feed their children sufficiently. Only in the twentieth century were effective drugs (sulfonamides and penicillin) against noma developed, as well as adequate surgical treatment for the sequelae of noma. These modes of treatment remain inaccessible for the many present-day victims of noma because of their extreme poverty. The only truly effective approach to the problem of noma throughout the world is prevention, namely, combating the extreme poverty with measures that lead to economic progress. In the meantime, medical doctors in the Western world should not forget their own history and ignore this global health problem; rather, they should face "the face of poverty" with the eyes of mercy and concern suited to their profession.     

Alleviation Mechanisms of Selenium on Cadmium-Spiked Neutrophil Injury to Chicken

To determine the negative effects of cadmium (Cd) exposure and the protective role of selenium (Se) on Cd-spiked neutrophils of chicken, forty-eight 28-day-old Isa Brown male chickens were divided randomly into four groups. Group I (control group) was fed with the basic diet containing 0.2 mg/kg Se. Group II (Se-treated group) was fed with the basic diet supplemented with Na₂SeO₃, and the total Se content was 2 mg/kg. Group III (Se/Cd-treated group) was fed with the basic diet supplemented with Na₂SeO₃; the total Se content was 2 mg/kg and supplemented with 150 mg/kg CdCl₂. Group IV (Cd-treated group) was fed with the basic diet supplemented with 150 mg/kg CdCl₂. Analyses of inflammatory factors, cytokines, and heat shock protein (Hsp) messenger RNA (mRNA) expression were detected by real-time PCR (RT-PCR). Additionally, we evaluated the phagocytic rate of neutrophils in peripheral blood. First, we observed that Cd significantly induced the mRNA expression levels of inflammatory factors NF-κB, iNOS, COX-2, and TNF-α, while Se/Cd treatment reduced their mRNA expression, although these expression levels remained higher than that of the control group. In addition, the mRNA expression levels of cytokines (IL-2, IL-4, and IL-10) for the Se-treated group exhibited significant differences between the Se/Cd-treated group and the Cd-treated group. Furthermore, the mRNA expression levels of Hsps demonstrated that the Se/Cd-treated group and the Cd-treated group were significantly higher (P < 0.05) than the control group and the Se-treated group. These results demonstrated that Se presented partial protection on Cd-spiked neutrophils of chicken with Hsps being involved in the process of the Cd-spiked toxic effects in chicken peripheral blood neutrophils.     

Alleviation of nickel toxicity by ammonium supply to sunflower plants

Phytotoxicity of nickel (Ni) varies within plant species and cultivars as well as with the concentration of Ni in the rooting medium. Moreover, it is known that several nutrients can modify the plant response to excess Ni. Nitrogen can be absorbed by plants as different N forms and because N metabolism and Ni are closely related, a hydroponic experiment was conducted to study the effect of Ni toxicity on the growth, nutrient status of the different plant parts and leaf chlorophyll concentrations in sunflower plants (Helianthus annuus L.) cv Quipu grown with different forms of N supply. The plants were grown under controlled conditions for 35 days. Depending on the N source supplied, there were significant differences in the sensitivity of sunflower plants to excess Ni. Tolerance was lowest when grown with NO₃ ⁻ alone. A high Ni and NO₃ ⁻ as the only N source resulted in reduced dry weight and significant decreases in nutrient concentration. Plants supplied with a mixture of NO₃ ⁻ and NH₄ ⁺ absorbed in the presence of Ni in solution about three times less Ni than those supplied with NO₃ ⁻ alone. Consequently, there were great differences in Ni concentrations between treatments. With a N nutrition of 100% NO₃ ⁻-N, Ni supply led to severe growth inhibition. Just contrary, simultaneous supply of NO₃ ⁻ and NH₄ ⁺ not only reduced Ni toxicity, but growth was even stimulated by Ni if supplied to plants fed with NO₃ ⁻ and NH₄ ⁺. This indicates the significant role of the N form supplied in the behaviour of Ni toxicity in sunflower plants. This revised version was published online in June 2006 with corrections to the Cover Date.