陕西省城乡居民收入差距的实证分析

以5年为1个考察期,对1981～2005年陕西省城乡居民平均绝对收入差距和平均相对收入差距进行考察和分析.结果发现:在5个考察期内,陕西城乡居民平均绝对收入差距呈现指数增长的趋势,平均相对收入差距也在不断上升.因此,只有不断对二元制度进行一元化改革和调整,对农业进行持续和足够的投资,才能从根本上缩小陕西城乡居民收入差距,缓解由城乡收入差距带来的各种社会矛盾,从而有利于和谐陕西早日实现.     

Crop water requirements revisited: The human dimensions of irrigation science and crop water management with special reference to the FAO approach

Halfway through the 20thcentury, a curious shift took place in theconcept and definition of the agronomic termcrop water requirements. Where these cropneeds were originally seen as the amount ofwater required for obtaining a certain yieldlevel, in the second half of the 20thcentury, the term came to mean the water neededto reach the potential or maximum yield in acertain season and locality. Some of themultiple academic, economic, social, andgeopolitical aspects of this conceptual shiftare addressed here. The crucial role of theproduction ecologist Cees de Wit in formulatingthis paradigmatic shift in the 1950s isdiscussed. It is seen how the incipient concernfor an expected global scarcity of waterresources has contributed to a trend back tothe conservative view of crop water control ofde Wit. The development over the years ofengineering and agricultural science conceptsconcerning irrigation and crop water control ispresented as an evolution from practicalhusbandry to specialized applied science;from an empirical, ecological approach to amainly physical/mathematical discipline. Inthe section ``The scientific heritage of Occamand Bacon,' it is argued that this developmentregarding irrigation is part of a general trendin agricultural (and other) sciences andtechnologies over the last 150 years, althoughtendencies to return to a more holisticapproach have, at times, occurred. The current mainstream concepts and methodsin the art and science of crop water control,far from being objective and value-free, oftenact as ``a siren song' for decision-makersresponsible for daily irrigation practice andregional or global water resource management.The seductive ``tune' of maximum yields,concurrently the highest crop water use, drownsout the more modest aim of making anefficient use of the available waterresources. The latter's allure might,however, become the morecompelling as a greater scarcity ofphysical water resources becomes moreimportant than scarcity of land and labor.     

刑法中严格责任的归责原则及适用

严格责任作为刑法中的一种归责原则,是英美法系国家刑法理论的一个特色。严格责任的存在有其合理性,值得借鉴,以构建符合我国国情的严格责任理论。     

基于稳定分布的证券投资组合模型

采用稳定分布描述证券收益率,以克服正态分布不能描述证券收益率“高峰厚尾”的问题,利用低阶矩代替传统正态分布的二阶矩构造了基于稳定分布的均值/绝对偏差投资组合模型,并在中国市场的实际情况下研究了模型的改进及解法,最后通过算例说明了模型的可行性。     

New Hippolide Derivatives with Protein Tyrosine Phosphatase 1B Inhibitory Activity from the Marine Sponge Hippospongia lachne

Five new sesterterpenoids, compounds 1–5, have been isolated from the sponge Hippospongia lachne off Yongxing Island in the South China Sea. The structures of compounds 1–5 were elucidated through extensive spectroscopic analysis, including HRMS, 1D, and 2D NMR experiments. The stereochemistry, including absolute configurations of these compounds, was determined by spectroscopic, chemical, and computational methods. Compounds 1 and 5 showed moderate protein tyrosine phosphatase 1B (PTP1B) inhibitory activities with IC₅₀ values of 5.2 μM and 8.7 μM, respectively, more potent than previously reported hippolides.     

改革开放以来江苏省区域经济差异变迁分析

以不变价格分别测算了苏南、苏中、苏北 ,以及 13个省辖市和 6 4个县市这 3个不同层次的江苏省区域经济差异 ,并进行了比较分析。认为 ,1978至 2 0 0 0年间 ,不论是绝对差异还是相对差异 ,江苏省区域经济差异都呈逐年扩大的变迁态势 ,并表现出不同的阶段性特征 ;而且区域层次划分得越小 (地域单元越小 ) ,所体现出的差异程度越大。     

The Response of Four Sorghum Accessions/Cultivars to Salinity During Plant Development

Whole-plant-response of four sorghum accessions to increasing mM NaCl concentrations of 0, 100, and 150 was assessed at three growth stages (GS-1, GS-2, and GS-3), in a sand-culture experiment. Accession comparisons were made on the basis of absolute and relative salt tolerance values. Increasing salinity significantly reduced plant height at GS-1, whilst shoot and root dry weight were less affected. The effect of NaCl on these characters was greater at GS-2 and GS-3, and accessions differed significantly in their responses to salinity. On the basis of plant height data, Giza 114 had the highest absolute salt tolerance at all three growth stages. However based on shoot and root dry weight data, Double TX and Giza 114 were both significantly more NaCl-tolerant than INRA 133 and INRA 353 at GS-2. Based on relative salt tolerance values of shoot and root dry weight, and plant height, Double TX and Giza 114 were more affected by salinity at GS-3 than INRA 133 and INRA 353. INRA 133 and INRA 353 exhibited progressively higher tolerance at all growth stages, and produced more grains than Double TX and Giza 114 , and consequently had higher grain yield per plant. NaCl salinity had little effect on grain weight. Plant sensitivity to NaCl at three growth stages differs in the four accessions, and is genotype-specific. This suggests that there is considerable variation in salt tolerance in sorghum at the adult stage which may be exploited through selection and breeding of plants to effect further improvement in salinity tolerance in this species.     

817优质肉鸡生长规律的研究

选择健康817肉鸡商品雏200只为试验材料,饲养期共8周,在初生和各周龄末空腹称重,计算各周绝对增重、相对增重及饲料利用率。从研究结果看,817肉鸡体重的增长规律与快大型肉鸡的生长规律基本相同,绝对增重在6周龄最高,饲料利用率随周龄增长而逐渐降低。从试验结果看,817肉鸡以6-8周龄出栏经济效益最好。     

哈尔滨地区初、终霜冻日分布特点的研究

通过对哈尔滨地区近５０年各级强度初、终霜冻日分布的研究,得出终霜冻的年际间差异比初霜冻大,且有强度大的霜冻年际间差异大而弱霜冻的年际间差异小的趋势,同时文中给出了各级强度霜冻指标出现的保证率曲线及各级保证率出现的相应日期。     

New Diterpenoids and Isocoumarin Derivatives from the Mangrove-Derived Fungus Hypoxylon sp.

Two new diterpenoids, hypoxyterpoids A (1) and B (2), and four new isocoumarin derivatives, hypoxymarins A–D (4–7), together, with seven known metabolites (3 and 8–13) were obtained from the crude extract of the mangrove-derived fungus Hypoxylon sp. The structures of the new compounds were elucidated on the basis of 1- and 2-dimensional (1D/2D) nuclear magnetic resonance (NMR) spectroscopic and mass spectrometric analysis. The absolute configurations of compounds 1, 2, 4, 5, and 7 were determined by comparison of experimental and calculated electronic circular dichroism (ECD) spectra, and the absolute configurations of C-4′ in 6 and C-9 in 7 were determined by [Rh₂(OCOCF₃)₄]-induced ECD spectra. Compound 1 showed moderate α-glucosidase inhibitory activities with IC₅₀ values of 741.5 ± 2.83 μM. Compounds 6 and 11 exhibited DPPH scavenging activities with IC₅₀ values of 15.36 ± 0.24 and 3.69 ± 0.07 μM, respectively.