农村产业结构调整应遵循的原则和采取的措施

农村产业结构是指一定时期和一定地区范围内，农村各产业部门之间，各产业内部的组合状况和比例关系。对农村产业结构进行调整，就是要建立一个合理的农村产业结构。     

Osmotic Adjustment in Maize (Zea mays L.): Changes with Ontogeny and its Relationship with Phenotypic Stability

Genetic variation for osmotic adjustment was examined in a group of maize hybrids during vegetative and silking stages. Estimates of osmotic adjustment were derived from measurements of leaf relative water content (RWC) and osmotic potential (Ψ o ) before day-break. The degree of adjustment was estimated from the In RWC/In Ψ o relationship. All cultivars examined showed some degree of osmotic adjustment and significant differences (P < 0.05) were found among them. The utility of measurements in early vegetative stages as a mean of selection for osmotic adjustment in silking stage was established. A positive tendency was observed between osmotic adjustment and phenotypic stability.     

大学生男女同居现象的道德调整与法律规制

大学生同居不仅会给女性身心和以后的婚姻家庭造成危害,而且会对社会造成危害。其产生的根源包括生理、心理、社会、文化等因素。对大学生进行道德调整和法律规范是完全必要的。     

女子沙滩排球垫球调整在比赛中的运用对比分析

通过文献资料法、录像统计法、观察分析法，以部分世界女子沙滩排球巡回赛、全国女子沙滩排球巡回赛为研究对象，对沙滩排球垫球调整技术在比赛中的运用进行研究分析。认为沙滩排球比赛受自然环境的影响和规则的限制，传球调整容易造成持球和连击，而我国沙滩排球队伍仍然更多采用传球调整技术。重视垫球调整是提高我国沙滩排球技战术水平与世界接轨的发展趋势，也是适应自然条件和适应规则的有效措施。     

Effect of water stress conditioning on morphology,physiology and field performance of Pinus halepensis Mill. seedlings

Five-month-old Pinus halepensis Mill. seedlings were subjected to 4 irrigation treatments for 8 weeks. After the treatments, morphological and physiologicalattributes assessed included height, diameter, dry weight, water relations parameters, and determination of N, P, K, soluble carbohydrates, and starch concentrations. The remaining seedlings were field planted. Survival and height growth were recorded forfour growing seasons after planting. The mostsignificant effect of irrigation was onmorphology. Increased irrigation lead toseedlings with significantly higher height,root collar diameter and shoot and rootbiomass. Starch and soluble carbohydrateconcentrations were also affected byirrigation. However, parameters derived frompressure-volume curves were not significantlydifferent among treatments, nor were N, P, andK concentrations. There were no differencesamong treatments for survival in the field,which was highly related to summer rainfall. Incomparison, absolute and relative heightgrowth showed some significant but minordifferences among treatments.     

Effects of the interaction between drought and shade on water relations, gas exchange and morphological traits in cork oak (Quercus suber L.) seedlings

The combined effect of drought and light on different physiological and biochemical traits was assessed in cork oak (Quercus suber L.) seedlings grown under two levels of light availability and submitted to a long-standing drought. Watering was withdrawn after germination and seedlings were allowed to dry to a water content of ca. 50% of field capacity. At this point, water-stressed seedlings were grown under moderate drought and two light regimes: high light (HL—50%) and low light (LL—2%). Soil water in control plants was kept close to field capacity (90–100%) for both light environments. Water-relations parameters derived from P–V curves, gas exchange and water status at predawn (Ψ_pd) were evaluated at twice during the experiment. Nitrogen and chlorophyll contents were determined in the same leaves used for the gas exchange measurements. In addition, maximum rate of carboxylation (V_cmax) and electronic transport (J_max) were derived from A–C_i curves in well-watered seedlings.

The variation on moisture availability during the experiment was the same under both light environments. In control plants, Ψ_pd was over −0.3 MPa at the two harvests, while stressed seedlings decreased to −0.9 MPa, with no differences between light treatments. Water stress decreased osmotic potentials at full (Ψπ₁₀₀) and zero turgor (Ψπ₀). The regressions between both potentials and Ψ_pd showed a higher intercept in shade grown seedlings. This fact will point out the higher osmoregulation capacity in sun seedlings whatever water availability.

Nitrogen investment on a per leaf mass (N_mass), chlorophyll content (Chl_mass) and SLA tended to show a typical pattern of sun-shade acclimation. Thus, the three parameters increased with shade. Only for N_mass there was a significant effect of watering, since water stress increased N_mass.

LL plants showed a lower photosynthetic capacity in terms of maximum net photosynthesis at saturating light (A_max), which was related to a decrease in V_cmax and J_max. Both parameters varied with specific leaf area (SLA) in a similar way. The low-light environment brought about a higher nitrogen investment in chlorophyll, while under high-light environment the investment was higher in carboxylation (V_cmax) and electronic transport (F_max).

Stomatal conductance to water vapour (g_wv) and A_max were lower in low-light seedlings independently of watering. In addition, there was a trend to keep higher intrinsic water use efficiency (IWUE) under high light environment. The increase of IWUE under water stress was higher in HL seedlings. This was as consequence of the steeper decline in g_wv as Ψ_pd decreased. The decrease of A_max with Ψ_pd occurred in a similar way in LL and HL seedlings. Thus, the HL seedlings tended to sustain a higher ability to increase IWUE than LL seedlings when they were submitted to the same water stress.     

加入WTO对江西花卉产业结构调整的思考

就江西省花卉产业的现状进行了分析,并阐述了中国加入WTO后,江西进行花卉产业结构调整的思路。     

国有林场树种结构调整及稳定性分析--以湖南省国有武冈林场为例

运用目标规划模型对湖南省国有武冈林场的森林树种结构进行优化,得到其理想的树种结构,然后计算出理想树种结构的信息熵和信息熵相对值,用于评价该场的树种结构稳定性.评价结果表明:该场1990～1999年的树种结构信息熵变化不大,稍有增势,比理想的树种结构信息熵偏小,这说明该场现有的树种结构处于过于有序状态,即,人工干扰过大,会损失某些利用功能.该评价结果可为其森林经营结构的调整提拱科学的参考依据.     

土地利用转型与农业生产结构调整的网络关联性研究—以四川省为例

土地利用转型与农业生产结构调整密切相关,具有互馈关联和交叉耦合的重要特征。如何认知其过程的网络关系已成为响应快速城镇化和乡村转型的一个重要话题,也是乡村振兴所关注的农村焦点问题之一。本文利用四川省土地利用和农村经济统计数据,分析了土地利用转型与农业生产结构调整的特征以及网络关联性。研究结果表明：1)1980—2018年期间,草地和水田减少的面积最多,其土地利用变化率分别为-0.72%和-0.64%,而城乡、工矿、居民用地和林地呈大幅增加,同时粮食作物产量占比大幅下降,而蔬菜产量占比增加了20.43%;2)土地利用转型与农业生产结构调整两大系统之间互馈关联的特征突出,尤其是林地和水域面积的变化同相对应的农产品变化表现出高度的关联性,而旱地变化的关联性具有分异性,突出了当前农业结构由粮食向蔬菜与经济作物转型的趋势;3)四川省五大经济区的土地利用转型与农业生产结构调整网络关联性的空间分布格局差异显著,表现为区域农业发展的主导产品与用地类型相互之间的影响关系最突出,而其余相对较弱。     

福建海洋渔业产业结构调整对策的探讨

一种产业的高速发展能否得以持续,关键在于是否对该产业结构进行不断调整,使之趋于最合理状态。为再度振兴福建海洋渔业,不失时机地进行渔业结构战略性调整是唯一选择。