沙漠生物结皮土壤发育特征的研究

通过对沙漠生物结皮层相关的土壤特性研究表明,结皮层不仅具有明显的养分富集和细粒物质的聚集作用,而且结皮层腐殖质成份的含量以及其分子结构和复杂程度也在增加。腐殖质光学特性的变化趋势明显反映了不同地区结皮层土壤发育的地带性特征。结皮层持水量明显高于沙层,并对降水再分配有一定影响。     

在LabVIEW程序运行中实现控件的动态移动

通过两种在LabVIEW程序运行中实现控件移动的方法的对比,着重介绍了结合了VI Sever技术的动态注册事件结构的用法,从而总结出其具有优化程序、减少内存、提高CPU利用率等方面的优点.     

热轧板退火温度对6×××系铝合金β"相析出动力学的影响

采用差示扫描量热法(DSC)研究热轧板退火温度对6×××系铝合金时效过程中β"相析出动力学的影响.计算热轧板在不同退火温度下β"相形成激活能,并对不同热轧板退火温度的试样模拟烤漆后进行力学性能实验.结果表明随着热轧板退火温度的提高,β"相的形成激活能略微降低,表明在时效过程中β"相更容易形成,合金的模拟烤漆强度因此得到提高.热轧板退火温度的提高,增大了基体中的Mg、Si原子的过饱和度,即增大了时效过程中β"相的形成驱动力,从而提高合金的模拟烤漆强度.     

长期酸化对红壤中活性固相铝库大小及亏损程度的影响

用连续分级提取和反复多次酸提取方法研究了长期土壤酸化对红壤固相铝库中铝含量及亏损程度的影响。研究结果表明:嵊县红壤的活性铝库大于永春红壤和屯溪红壤;因永春红壤和屯溪红壤的酸化程度大于嵊县红壤,前两者的有机铝库和无机铝库都比嵊县红壤的亏损,因此反复酸提取过程中铝的释放量也比嵊县红壤少;当高强度酸输入土壤后,弱键合的有机络合态铝可快速活化并亏损,剩余铝库因活性小而释放速率减小,但长期酸化过程中,动力学控制的低活性铝库的活化可能对铝的溶解量仍有重要贡献。     

一种改进的图像域SAR目标散射中心特征提取方法

散射中心是SAR图像目标识别的重要特征。本文基于属性散射中心模型，在文献[6]的基础上，提出了一种改进的图像域SAR目标散射中心特征提取方法。在该方法中，通过引入参数规则化处理步骤，解决了属性散射中心特征提取方法的收敛问题，提高了属性散射中心特征参数估计的精度和效率；提出了一种能同时实现散射中心数目确定和结构判别的方法，实现了散射中心类型的可靠判别。仿真数据和MSTAR实测SAR图像数据的实验结果，验证了本文改进的图像域SAR目标散射中心特征提取方法的有效性。     

土卡河水电站混凝土新型复合掺合料研究与应用

土卡河水电站采用磨细矿渣加石灰石粉的新型复合掺合料替代粉煤灰作为混凝土中掺合料。文章介绍了这种新型复合掺合料的性能和应用情况。     

LP-BM5 virus causes changes in lactic dehydrogenase and oxygen radical production in splenocytes of C57BL/6J mice

The LP-BM5 murine leukemia virus causes acquired immunodeficiency syndrome in C57BL/6J mice (MAIDS), similar to that of AIDS in humans. The objective of this study was to determine the effect of LP-BM5 viral infection on cellular activation and membrane integrity of splenocytes. Oxidative burst in splenocytes in response to exposure to PMA (20 microg/ml) was significantly higher (p<.02) in infected than in control mice at two weeks post-infection using luminol-enhanced chemiluminescence. By 13 weeks post-infection superoxide anion production in infected mice was significantly lower when compared to controls coinciding with decreased proliferative response to mitogens. The extent of cell membrane damage as indicated by lactic dehydrogenase (LDH) activity in serum was significantly higher in infected than in control mice (p<.001). The results from this study suggests that LP-BM5 virus causes an initial stimulation of cellular activity followed by a decreased cell activation characterized by decreased proliferation of splenocytes and decreased oxygen radical production. Decreased cell membrane integrity indicated by increased LDH activity may partly be responsible for these changes.     

ATP-sensitive voltage- and calcium-dependent chloride channels in sarcoplasmic reticulum vesicles from rabbit skeletal muscle

In addition to its role in olfaction and as a primary epileptogenic site, the anterior piriform cortex has been suggested to play a role in neuroperception of deficiencies or imbalances in physiologically essential amino acids. In recent studies, amino acid deficient diets were shown to induce expression of c-fos in the anterior piriform cortex within the rapid time frame associated with the normal anorectic response to such diets. It became important to examine the neurocytochemical architecture of this region for clues as to how and more precisely where dietary amino acid deficiency or imbalance might be monitored. The relationships of neuropeptide Y-, somatostatin-, and cholecystokinin-containing neurons were of particular interest because ongoing studies indicate that those peptides administered to the anterior piriform cortex alter intake of diets deficient in essential amino acids. The neuropeptides were endogenous to intrinsic neurons only; none resembled pyramidal projection neurons. Peptidergic neurons and fibers were concentrated most heavily in layer III of the paleocortex. The cytoarchitecture suggests that neuropeptide Y-, somatostatin-, and cholecystokin-containing neurons of the anterior piriform cortex may relate synaptically or multisynaptically to local circuit neurons during electrical activity, modulation of olfactory information, and neuroperception of essential amino acids.     

Development of calcium signalling mechanisms during maturation of human oocytes

Sperm-induced Ca2+ signals mediate the events of oocyte activation at fertilization. In this study, the development of mechanisms involved in the generation of Ca2+ signals in human oocytes was investigated. The thiol reagent, thimerosal, which induces oscillations of intracellular Ca2+ ([Ca2+]i) similar to those seen during fertilization, was used to mobilize Ca2+ in in-vivo matured, immature and in-vitro matured human oocytes. There was an increase in the sensitivity to thimerosal during maturation of human oocytes, with oocytes from small antral follicles being relatively insensitive, compared with those from luteinized follicles, which displayed a large spike followed by sustained oscillations in [Ca2+]i. These oscillations were inhibited by caffeine which suggests that they were mediated by the inositol trisphosphate receptor Ca2+ release system. When immature oocytes were cultured in vitro they acquired the capacity to undergo a single large spike in [Ca2+]i, however, subsequent sustained oscillations were not observed, indicating that these oocytes failed to develop fully competent Ca2+ signalling mechanisms during culture in vitro. This finding may be a key factor in the poor developmental competence of in-vitro matured human oocytes.