中国北方典型地区农用地膜污染现状调查及其防治对策

通过对我国北方典型地区的调查,初步探索了该地区土壤农膜残留量和残膜特征.研究表明,河北省典型地区温室大棚、蔬菜田和作物田的农膜土壤残留量平均分别为5.629、7.369和2.822 kg·hm-2,黑龙江省典型地区温室大棚、蔬菜田和作物田残留量平均分别为4.169、3.682和2.430 kg·hm-2,各采样点之间存在着较大差异,但普遍较高,均明显高于未使用农膜的对照土壤.两地区之间除作物田的土壤农膜残留量没有明显差异外,河北地区其他两类土壤中的农膜残留量水平明显高于黑龙江地区,这种差异与各地区在农事活动及农膜使用上的差异具有一定的相关性.上述两地区土壤中残留农膜尺寸基本一致,主要集中在10～15 cm之间.该文针对我国目前农膜使用情况及其污染现状,提出了相应的防治对策.     

USE OF 3'-DEOXY-3'-[18F]FLUOROTHYMIDINE PET/CT FOR EVALUATING RESPONSE TO CYTOTOXIC CHEMOTHERAPY IN DOGS WITH NON-HODGKIN'S LYMPHOMA

Imaging and measurement of proliferation with computed tomography (CT) and positron emission tomography (PET) provide a noninvasive method for improved staging and monitoring of response to cancer treatment. We evaluated prospectively the proliferation marker 3'-deoxy-3'[¹⁸F] fluorothymidine (FLT) in the context of FLT-PET/CT for detection of early response, confirmation of posttreatment response, and prediction of relapse in dogs with non-Hodgkin's lymphoma. Nine dogs with non-Hodgkin's lymphoma who were scheduled to receive five cycles of an investigational cytotoxic chemotherapy agent were included. All dogs received baseline FLT-PET/CT imaging immediately before chemotherapy. Intent was to repeat imaging with FLT-PET/CT at various time points: group 1 ( n =4), 5 days after initiation of chemotherapy and 3 weeks following the last chemotherapy administration; group 2 ( n =5), before the fourth cycle of chemotherapy and 3 weeks following the last administration. Two dogs in group 2 did not undergo repeat PET/CT. Body mass standardized uptake values (SUV) for FLT were calculated for each dog. Eight dogs had initially increased FLT uptake (mean SUV_max=9.8 [2.6–22.3]). Mean SUV decreased significantly for the seven dogs that underwent follow-up PET/CT following chemotherapy (mean SUV_max=3.5 [1.1–7.9], P <0.016). Increased uptake preceded clinical and cytological evidence of relapse in two dogs. Ki-67 immunohistochemistry confirmed decreased proliferation corresponding to decreased SUV in three canine lymph node samples. FLT-PET/CT functional and anatomical imaging shows promise for the evaluation of response to cytotoxic chemotherapy in dogs with non-Hodgkin's lymphoma and for predicting relapse before standard clinical and clinicopathologic confirmation.     

6-硫-6-烷硫基-12H-氯代双苯并[d,g][1,3,2]-二氧磷杂八环的合成

通过双- (2 -羟基 -氯代苯基 )甲烷 2与 P4S10 在三乙胺存在下的关环反应 ,得到了6 -硫 - 6巯基 - 12 H-氯代双苯并 [d,g][1,3,2 ]-二氧磷杂八环三乙胺盐 3,后者与卤代烷酯化得到了一系列 6 -硫 - 6 -烷硫基 - 12 H-氯代双苯并 [d,g][1,3,2 ]-二氧磷杂八环 4 ,测试并讨论了它们的1H和31P NMR数据。初步生物试验结果表明化合物 4对黄瓜霜霉病菌具有较好的抑制活性。     

怎样高枝嫁接落叶松

怎样高枝嫁接落叶松落叶松利用春季进行高枝嫁接，一般成活率可达到９５％以上，当年新梢生长量达１米左右，可使种子园提前１０～１５年建成。具体方法是：１．选择接穗。落叶松芽萌动前，在落叶松优良家系的植株上选择芽饱满的１～３年生枝条，剪后埋在背阴处备用。２．...     

花团状纳米铜的表征及抑菌性能研究

以六元瓜环(Q[6])为修饰剂,抗坏血酸为还原剂,硫酸铜为铜源,采用液相化学还原法制备纳米铜。并利用XRD和SEM方法对产物进行了表征,结果显示目标产物为花团状单质纳米铜。然后考察了纳米铜对革兰氏阴性菌大肠杆菌的抑制情况,结果表明,250μg/m L花状纳米铜对大肠杆菌具有良好的抑制作用。     

土壤类型对凉山烤烟品质的影响

以云烟87为材料,在盐源烟区选取5种不同类型土壤进行烤烟大田栽培,研究了四川凉山土壤类型对烤烟主要化学成分、中性致香物质及内在质量的影响。结果表明,参试土壤钙、镁含量较丰富,明显缺氯;紫色土、红壤、黄壤、沉积土等明显缺钾和氮;水稻土和沉积土缺磷。不同土壤烤后烟叶化学成分有差异,水稻土和紫色土上烤后烟叶烟碱、总氮含量较高,糖含量较低,基本符合优质烟叶质量标准;红壤、紫色土和黄壤上烤后烟叶钾含量相对较高,接近优质烟叶钾含量;沉积土、水稻土和红壤上烤后烟叶氯含量较高,接近优质烟叶氯含量。不同土壤烤后烟叶致香物质含量差异较大,黄壤和红壤上烤后烟叶苯丙氨酸类降解产物含量较高;黄壤、红壤和水稻土上烤后烟叶类西柏烷类产物含量较高;水稻土、紫色土和红壤上烤后烟叶质体色素降解产物含量及致香成分总量较高。不同土壤烤后烟叶内在质量存在一定的差异,由高到低对应的植烟土壤依次为:紫色土、红壤、黄壤、沉积土、水稻土。     

Effects of aromatase inhibitors on reproduction in male three-spined sticklebacks, Gasterosteus aculeatus, exposed to long and short photoperiods

Three-spined stickleback Gasterosteus aculeatus, males were implanted with Silastic capsules filled with different aromatase inhibitors; 1,4,6-androstatriene-3,17-dione or the non-steroidal CGS16949 A, 4-(5,6,7,8-tetrahydrimidazol [1,5-a]pyridin-5-yl) benzonitrile monohydrochloride or empty capsules. The fish were then exposed to long or short photoperiod. Under the long photoperiod most fish in all treatments displayed a hypertrophied kidney (a secondary sexual character in sticklebacks) and completed, quiescent spermatogenesis, similar as in the natural spawning period. Under the short photoperiod the controls had unstimulated kidneys and an active spermatogenesis, whereas the males implanted with both aromatase inhibitors had stimulated kidneys, though not to the extent as in the long photoperiod, and completed, quiescent spermatogenesis. These findings suggest that aromatization is of importance for the inhibitory effects of short photoperiod on reproduction in the stickleback. This revised version was published online in July 2006 with corrections to the Cover Date.     

4种填闲作物对天津黄瓜温室土壤次生盐渍化改良作用的初步研究

通过夏季填闲的方式来解决设施农业次生盐渍化在20世纪初就已被提出,但相关研究在天津黄瓜温室土壤次生盐渍化改良方面还没有开展。通过盆栽试验研究了4种填闲作物（毛苕子、苏丹草、甜玉米和苋菜）对天津地区黄瓜温室土壤次生盐渍化的改良作用。结果显示,与对照土壤相比,4种填闲作物均能显著降低土壤可溶性盐分和Na^＋的含量（P〈0．05）,显著降低土壤养分和有机质的含量（P〈0．05）;毛苕子、甜玉米和苋菜能显著增大土壤K^＋／Na^＋的比值;高种植密度对次生盐渍化土壤的改良效果更为突出;4种填闲作物相比,毛苕子对黄瓜温室土壤次生盐渍化的改良效果最佳。既为改良天津黄瓜温室土壤次生盐渍化提供实践参考,也为延长设施土壤使用年限,促进天津设施蔬菜产业发展提供一种可行途径。     

RSA加密方式中Montgomery算法的研究与改进

运算安全和运算效率问题是目前RSA加密体制的关键问题.实际应用中RSA密码算法加密、解密运算均为模幂运算,即Me mod N.将模幂运算转换为一系列模乘运算便于硬件实现,并且可以进行并行运行,提高运算效率.本文主要通过对Montgomery算法进行研究,然后提出改进的高基Montgomery算法来提高RSA密码算法的运算速度和执行效率.     

青海省东部黄土丘陵沟壑区泥石流及其防治对策

青海省东部黄土高原丘陵沟壑区高寒干旱，山大沟深，沟壑纵横，生态失调，暴雨频繁，水土流失严重，滑坡、泥石流程度不同地不断发生，严重危害着工农业生产和人民生命财产安全。据调查分析，造成海东泥石流的主要成因，与暴雨、地质、气候、地形、黄土以及人为活动因素有关。防治泥石流灾害必须采取以下措施：全面普查，掌握情况；开展监测工作，进行科学试验；加快坡面、沟道治理；加强管理，依法制止人为水土流失。