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。     

汽车前照灯智能控制系统的设计

基于汽车驾驶的安全性,结合传感器技术和微控制技术,对汽车前照灯设计了一套智能控制系统。该系统能在不同的情况下,对前照灯的照射角度和亮度进行自动实时调整和自动选择适宜的灯光模式,实现汽车前照灯的智能化控制,提高了汽车驾驶的安全性、舒适性以及智能感觉。     

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。     

沙芦草种子发芽抑制物的初步探究

沙芦草又称蒙古冰草,具有抗旱、抗寒、抗病、耐盐碱等优良性状,是荒漠草原和典型草原地带沙地主要植被之一。沙芦草种子存在发芽率低、发芽持续时间长等野生特性,这对沙芦草人工种子繁育和生产利用造成一定程度的影响。为探究沙芦草种子休眠机制,试验分别用石油醚、乙醚、乙酸乙酯、甲醇、丙酮等5种有机溶剂和纯水对沙芦草种子稃壳进行浸提,利用白菜种子发芽试验测定各提取相的抑制性,通过气相色谱-质谱联用仪（GC-MS）对5种有机溶剂浸提液进行分离鉴定,确定浸提物质的种类和性质。结果表明：沙芦草种子稃壳的各相浸提液对白菜种子的发芽率、根长及苗高均有不同程度的抑制作用,其中抑制作用最强的是水相,其次是乙酸乙酯相和甲醇相;通过GC-MS检测,发现沙芦草种子稃壳中存在烷类、醇类、酯类、酮类、苯类、酰胺、缩醛、酸类和酚类等9类32种有机化合物,其中醇类、酮类和烷类物质的含量相对较高,且大部分为水溶性物质。因此,沙芦草种子稃壳中存在的醇类、酮类和烷类等可溶性物质是引起沙芦草种子休眠的主要原因之一,该研究可为寻找沙芦草种子休眠破除方法提供理论依据。     

植物自毒作用及针叶林自毒研究进展

自毒作用是同种植物个体之间的一种化学作用,是植物经过长期适应环境和进化选择而获得的一种避免种内竞争的机制.针叶树是我国重要的用材树种,在对其长期的经营管理过程中发现:天然针叶林经常会出现生产力下降和天然更新障碍等问题.除轮伐期、采伐利用方式不当等原因外,针叶树凋落物和根分泌物长期向环境中释放大量次生代谢物质,而自然生态系统的排毒解毒机制受到人为干扰的影响,导致植物次生代谢物质的过量积累,进而产生了自毒作用,这也是许多作物连作障碍产生的原因.就自毒物质的种类、释放途径、作用特点、作用机理、检测方法、对生态系统的影响及针叶林自毒作用的研究现状等问题进行综述.认为对自毒作用研究的最终目的是要为解决困扰我们的各种生态环境问题提供切实可行的方案,尤其是在实现农林业可持续发展和自然资源与环境保护方面发挥作用.     

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.     

Thermal properties of interior decorating material and the sensation of cold/warm by contact II: the relations among heat flux, temperature change of material, and sensation of cold/warm by contact

The main purpose of this study was to investigate the changes in heat flux and temperature after the subject's palm was in contact with interior decorating materials. The relations among heat flux, temperature, and sensation of cold/warm during contact were studied. Ten men and ten women were selected and introduced to 21 materials for the contact test. They were in contact with the specimens for 30min without seeing them in a climate-controlled room at 25°±1°C and 65% RH. Changes in the heat flux and temperature of the specimens were determined by a heat flux meter. A sensory evaluation test was applied to evaluate the cold-warm contact. Results indicated that the heat flux and temperature increased with increasing time after the subject's palm was in contact with the specimens. The heat flux (Q ₃₀) and temperature (T ₃₀) 30min after the subject's palm contacted the specimens were greater for male subjects than for female subjects. A positive linear regression equation existed between the values for Q₃₀ andT ₃₀, whereas a negative linear regression formula existed the sensation of cold-warm by contact (5) and the values of ln(Q ₁·). Therefore, the sensation of cold/warm by contact could be estimated simply by using the thermal physical properties of the interior decorating materials.Part of this report was presented at the International Conference on Effective Utilization of Plantation Timber, Chi-Tou, Taiwan, ROC, May 1999     

Fertilizer-induced Changes in Rhizosphere Electrical Conductivity: Relation to Forest Tree Seedling Root System Growth and Function

Fertilization is standard practice in forest tree seedling nursery culture. Additionally, fertilization at outplanting has potential to facilitate nutrient uptake and reduce transplant shock. Fertilization, however, may dramatically alter rhizosphere chemical properties such as pH, ion availability, and electrical conductivity (EC). These changes may inhibit root system growth and function by reducing soil osmotic potential and creating specific ion toxicities. The risk of root damage associated with high EC levels appears to be dependent on species, age of root system, and soil moisture availability. Root inhibition in container nursery culture of conifers is likely to occur above 2.5 dS m⁻¹, though threshold EC levels for bareroot culture and field plantings are largely unavailable. Fertilization at outplanting has the added risk that drought conditions may prevent leaching of excess fertilizer salts, which can increase rhizosphere EC beyond safe levels and ultimately impair root uptake of water or nutrients. For fertilization programs to be successful, a critical threshold balance must be maintained between optimizing seedling nutrient availability in the rhizosphere, while minimizing potential for root damage. Future research is needed to identify optimal EC levels for a range of species across all stages of the reforestation process, from nursery culture through plantation establishment.     

锈色粒肩天牛与寄主树种关系的初步研究

在连续 3a的定位观测和分析基础上 ,本文初步报道了锈色粒肩天牛与文献报道中的几种寄主树种之间的关系。结果如下 :(1)根据室内饲养下成虫对不同树种的取食及产卵情况和在不同树种上接种 (卵 )的幼虫情况 ,可将几种寄主树种分为 4类 :高感树种 (国槐 )、低感树种 (云实、黄檀 )、抗虫树种 (刺槐 )、免疫树种 (旱柳 ) ;(2 )酚酸类物质在旱柳中的含量 (3 0 3～ 9 73mg·(10 0g) - 1 ) ,显著高于其它树种中的含量 (1 71～5 39mg·(10 0g) - 1 ) ,可能是锈色粒肩天牛在旱柳上表现拒食、拒产卵、拒钻蛀的重要原因。氨基酸含量较高、组分相对最全 (17种 ) ,以及较高的C N值 ,是国槐基本营养物质的显著特征 ,这可能是锈色粒肩天牛嗜食国槐 ,对其造成严重危害的根本原因。锈色粒肩天牛很少取食危害刺槐 ,这与刺槐树种的各部分C N值过低 ,造成营养失调有关。黄檀木材纤维平均长度为 0 837mm ,平均宽度为 18 90 μm ,长宽比为 5 0 96 ,其韧性是参试树种中最大的 ,因而可能造成幼虫啃食困难 ,加上木材中的C N低 (0 36 ) ,因此 ,具有较强的抗虫性。云实树皮薄而光滑 ,造成成虫产卵困难 ,因此 ,在自然状态下 ,锈色粒肩天牛不易对其产生危害。     

不同覆盖处理对元宝枫叶生物活性物质含量的影响

以2年生元宝枫苗为试材,对其进行不同覆盖处理,测定叶内黄酮、绿原酸、叶绿素、SOD活性酶和丙二醛的含量,并进行方差分析和多重比较.结果表明:不同覆盖处理对元宝枫叶中生物活性物质含量的影响十分明显,黄酮含量在白膜覆盖下最高,绿原酸和叶绿素含量在绿膜覆盖下最高,SOD酶活性和丙二醛含量在红膜覆盖下最高,黄酮、叶绿素、丙二醛含量在不同覆盖处理下均以α=0.01水平上差异极显著,SOD酶活性和绿原酸含量以α=0.05水平上差异显著.