6S辐射校正与像元分解结合提高苹果树花期冠层反射率反演精度

为了获取近似真实的苹果树冠层反射率,该文以山东省栖霞市为研究区,应用DEM数据和6S辐射传输模型,对苹果树花期TM影像进行辐射校正、混合像元分解,获取26个果园苹果树冠层反演反射率,将反演结果与相同时段地面实测冠层反射率以及表观反射率、表观—像元分解反射率进行比较,分析了反演效果及精度。结果表明,地表反演反射率有效减弱了地形和大气的影响,恢复了阴影处的地物,影像清晰度明显提高;苹果树冠层反演反射率样本平均值误差较表观、表观—像元分解、地表反演3类反射率小,与实测值的相关系数提高,而且样本间变化趋势与实测值基本一致。此反演方法具有一定可行性,对于苹果树冠层反射率和苹果园管理基础数据获取与应用具有积极意义,也可为其他农业遥感反演研究及应用提供借鉴。     

对当前征占用林地管理主要问题之反思

根据全国连清资料,我国每年有林地转变为非林地的面积为56.2万hm2,目前我国林地管理存在着管理部门之间关系混乱、行政干预严重、林业部门自身执法犯法问题突出等问题。分析了造成这些问题的原因,提出了建立健全法制、理顺管理关系、加大案件查处力度、加强执法队伍建设、加大舆论宣传等对策。     

An Analysis to the Driving Forces for Water and Salt Absorption in Roots of Maize Seedlings Under Salt Stress

When maize seedlings were subjected to salt stress,a decline in root xylem pressure was observed within seconds,followed by a gradual increase in Na＋ deposition in the seedlings.The magnitude of xylem pressure response was positively correlated with,but not proportional to the intensity of the stress.A continuous recording of the xylem pressure profile showed that self-regulation of the xylem pressure existed before and after the imposition of salt stress when the environmental conditions were relatively stable.The salt induced increase in xylem tension dominated the total water potential of the plant when the salt stress was mild,but the osmotic potential became more prominent when the NaCl concentration in the root bathing solution was raised to over 100 mol m-3.The average transpiration rate of the seedlings dropped by 40% when the NaCl concentration in the root ambient was increased to 150 mol m-3.Although salt stress resulted in the decline of both the xylem pressure potential and the osmotic potential in the root xylem,the changes in the total water potential of the root xylem solution were always smaller than the changes in the water （osmotic） potentials of the solution bathing the root.An analysis to the water relations of maize seedlings showed that not only the water potential components,but the radial reflection coefficient of the roots was also dependent on the level of salinity.When the NaCl level in the root bathing solution was raised from 25 to 150 mol m-3,the radial reflection coefficient of the root declined from 0.43 to 0.31.This small change resulted in a remarkable increase in the normalised relative NaCl absorption by 2.4 times,indicating that the radial reflection coefficient of root played a very important role in regulating the absorption of NaCl in maize seedlings under salt stress.     

关于大学生"回炉"的几点思考

大学生毕业后再到技校重学一门技术的现象越来越引起社会的关注。为使高等院校更好地培养有用的高素质人才,本文对这一现象的成因进行了分析,认为传统教学模式、大学生择业理想与用人单位要求之间的矛盾以及激烈的就业竞争是大学生“回炉”的主要原因,并从育人理念、课程设置、实践环节、开放办学和发展高等职业教育等几个方面提出了对策。     

加强林政执法工作的对策与建议

分析了目前林政执法的现状,并对我国林政执法工作中存在的问题进行了阐述,从建立健全林业综合执法机构、加强执法制度建设、完善执法体系等方面提出了林政资源管理创新的对策与建议。     

浠水县马尾松产业现状的分析和思考

分析和探讨了马尾松现状及产生的原因,提出了通过抚育采伐、补种阔叶树营造混交林、皆伐后重新造林等低产低效改造措施和进行封山育林、加强病虫害和森林火灾防治、加强资源林政管理等管理措施来改变现状,为促进马尾松产业发展提供参考。     

提高人才培养质量的思考——以苏州农业职业技术学院为例

我国高等职业教育在经历了多年的发展后,取得了突破性的进展,但如何更好地提高人才培养的质量,仍然在不断探索。高职人才培养目标是真正体现以市场为导向,本着以人为本的理念,培养出高素质的技能型人才。提出了提高人才培养质量的措施是明确培养目标,加强专业建设;加大课改力度,做实课程建设;加强团队建设,提高双师素质;加大教学投入,不断改善基础实施;推进教育创新,深化教学改革。     

不同遗传型棉花品种光谱反射特性研究

不同遗传型棉花品种有不同的光谱反射特性,黄叶棉在可见光区的反射率最高,红叶棉最低,绿叶棉居中,绿叶鸡脚叶与普通叶无明显差异;黄叶棉和绿叶棉在可见光区的反射峰在５６０ｎｍ处,而红叶棉在６１０ｎｍ处;近红外反射率可在一定程度上反映棉花群体大小的差异。     

经济哲学:哲学对人类经济世界的反思

经济哲学不是经济学的元学科,也不是经济学和哲学两个学科的联盟、结合,更不是哲学在经济领域的具体运用。作为一种部门哲学,经济哲学是根据哲学思维的根本特性反思人类经济世界而形成的哲学理论,它是对于人类经济世界的总体性把握,是一种关于人类经济世界的哲学观。     

Effects of 8 hemodynamic conditions on direct blood pressure values obtained simultaneously from the carotid,femoral and dorsal pedal arteries in dogs

ObjectivesThis study aimed to evaluate the effect of 8 hemodynamic conditions on blood pressure measurements taken from the carotid, femoral and dorsal pedal arteries of dogs.AnimalsSix healthy dogs.MethodsDuring isoflurane anesthesia, catheters were introduced into the carotid, femoral and dorsal pedal arteries of dogs to allow simultaneous monitoring of direct blood pressure in each artery. The dogs were submitted to 8 hemodynamic conditions induced by combining changes in heart rate (bradycardia, normocardia, tachycardia) with changes in blood pressure (hypotension, normotension, hypertension). Values obtained from each arterial catheter were compared and agreement between central (carotid) and peripheral (femoral and dorsal pedal) values were analyzed by the Bland–Altman method.ResultsDuring hypotensive conditions, systolic arterial pressure (SAP) was lower in the femoral and dorsal pedal arteries compared to the carotid artery whereas during normotensive and hypertensive conditions, SAP was higher in peripheral arteries. During hypotensive states, increases in heart rate resulted in greater bias between central and peripheral SAP whereas during normotensive states, the bias decreased as heart rate increased. Mean and diastolic arterial pressures were lower in the femoral and dorsal pedal arteries than in the carotid artery during most hemodynamic conditions.ConclusionsIn healthy anesthetized dogs, invasive blood pressure measurements in peripheral arteries may differ significantly from measurements in a central artery. The greatest differences were observed in SAP and the magnitude of differences between central and peripheral blood pressure measurements varied according to the dog's hemodynamic condition.