一类二阶非线性微分方程解的零点存在定理

通过建立两个微分恒等式,讨论了一类二阶非线性微分方程解的零点存在性,得到了2个非线性微分方程解的零点存在定理,并以实例说明了其有效性．     

湿地松半同胞家系净光合速率的比较研究及季节变异规律

为研究湿地松半同胞家系间净光合速率的差异及其季节变异规律,应用LI－6400便携式光合测定系统,对湿地松优良半同胞家系一年中各月净光合速率、最大净光合速率进行了研究,结果表明一年中湿地松各半同胞家系1龄针叶、2龄针叶净光合速率、最大净光合速率的季节变异规律呈‘双峰’型,家系内不同单株同龄针叶的净光合速率值没有显著差异,而家系间相同年龄针叶的净光合速率值则存在着显著差异。一年中1龄针叶以家系464、609、1077的净光合速率较高、普通种最低,其值分别为8.17、7.91、7.88和5.46μmol•m-2•s-1,而2龄针叶以家系1077、609、46的净光合速率较高、普通种最低,其值分别为5.47、5.42、5.37和3.65μmol•m-2•s-1。湿地松各家系1龄针叶的净光合速率值、最大净光合速率值显著高于2龄针叶的净光合速率值和最大净光合速率值。各家系1龄针叶的净光合速率值仅为最大净光合速率值的64.41%、2龄针叶的净光合速率值仅为最大净光合速率值的54.44%。表明湿地松高光效育种的改良潜力较大,通过合理利用和调整育林措施,可提高湿地松优良家系的生长量和产量。     

Mechanical Behaviors of Large Span Space Structures in the Construction Process

Traditional structural design emphasizes checking whether a loaded structure satisfies design requirements without considering the construction process. There is a great difference in structures between the states in construction processes and design, however. To solve the above problems, a method of nonlinear time varying mechanics was adopted to analyze the construction process of a structure. The structural characteristics in each construction stage were analyzed by time varying mechanics and the variations of internal force and displacements obtained. We conclude that designs will not be safe if the time varying effect in the construction process analysis is not considered. We offer advice on the design and construction of large span structures.     

Synthesis of cobalt phthalocyanine under microave irradiationand determination of bovine albumin

Cobalt phthalocyanine （CoPc）was prepared from phthalodinitrile and cobalt sulfate via microwave irradiation. The Resonance Rayleigh scattering（RRS）was enhnaced by the interaction of sulfonated CoPc and bovine albumin（BA）. An RRS peak formed at 460 nm with intensity proportional to the concentration of BA. A simple and rapid method of RRS for the determination of BA thus was established. The linear range is 0.1 ug/mL to~6.0 ug/mL. The detection limit for BA is 5.73 ng/mL.     

Magnetic properties measurement of antisense oligodeoxynucleotide probes labeled by superparamagnetic iron oxide

The c erbB2 oncogene antisense oligodeoxynucleotide probe was obtained by chemical cross linking approach. Its T2 relaxivity was 0.156×106 mo l－1·s－1 , which was determined with a 1.5T MR system. The saturated magnetization, specific saturated magnetization, specific retentivity and retentivity were 69.423 8emu/g Fe, 68.413 4e mu/g, 30.354 1e mu/g and 19.734 5 Gs, respectively. These measurements were obtained with a vibrating sample magnetometer. To test its effectiveness, highly expressive SK Br 3 oncocytes were transfected with the antisense oligodeoxynucleotide probe. Meanwhile, SK Br 3 oncocytes were transfected with the sense and non sense oligodeoxynucleotide probe, and normal mouse liver cells were transfected with the antisense oligodeoxynucleotide probe. The results show that the antisense probe could enter the SK Br 3 oncocytes effectively, and improve the magnetic properties and decrease the signal intensity in MR scanning obviously.     

Quality and internal characteristics of Huanghua pears (Pyrus pyrifolia Nakai, cv. Huanghua) treated with different kinds of coatings during storage

We studied the quality and internal changes in Huanghua pears (Pyrus pyrifolia Nakai, cv. Huanghua) coated with shellac, Semperfresh™ (sucrose polyester base coating), and carboxymethyl chitosan (CMC) during cold storage (4 °C). The changes in respiration rate, weight loss, cell membrane permeability and texture profile analysis (TPA) such as hardness, brittleness and chewiness were recorded periodically for up to 60 days after harvest to compare the effects of the applied coatings. Magnetic resonance (MR) imaging was used to inspect the internal characteristics of pears after storage. The soluble solids contents (SSCs), titratable acidity (TA), ascorbic acid concentration, and taste scores were also measured. Our data suggest that shellac coating was more effective in reducing the respiration rate and weight loss and in maintaining the quality of pears than Semperfresh and CMC coatings.     

Separation of liquefied product of Salix psammophila by column chromatography and structure analysis of its components

The liquefied product of Salix psammophila wood was separated by thin-layer chromatography (TLC) and column chro-matography, and its structure was identified by nuclear magnetic resonance (NMR) spectra in our study. The separation result indi-cates that the sample of liquefied S. psammophila contained at least two categories of components. The structure of the main compo-nents was guaiacyl C-1, C-2 of the hydroxyphenyl propane, i.e., the aromatic nucleus protons of lignin. Degradation and polycon-densation reactions occurred when the S. psammophila wood was liquefied in phenol. Polycondensation reactions occurred among the depolymerization products from cellulose, the aromatic depolymerization products from lignin and the products of the displace-ment reactions between phenoxide ion and cellulose.     

液氮冻结软壳青蟹在冻藏期间的营养物质变化

为探讨液氮(LN)冻结拟穴青蟹软壳蟹在冻藏期间的营养物质变化,本研究采用基于核磁共振(NMR)的代谢组学技术分析了LN冻结软壳蟹可食组织代谢谱在短期(7 d)和长期(8个月)冻藏期间的变化。结果表明,-20℃冻藏和LN冻结均对短期冻藏的软壳蟹代谢谱无显著影响(P>0.05),但 -20℃ 冻藏导致软壳蟹肌肉的二甲胺和肝胰腺的肌苷水平倍增,而LN冻结能抑制这两种物质的增加。长期冻藏可导致LN冻结软壳蟹肌肉的肌苷、麦芽糖和葡萄糖以及肝胰腺的肌苷、谷氨酰胺和尿苷水平显著升高(P<0.05)。表明LN冻结可有效缓解长期冻藏软壳蟹的质量下降。本研究结果为揭示软壳蟹冻藏过程中的品质变化提供了理论参考。     

USE OF RADIOGRAPHY, COMPUTED TOMOGRAPHY AND MAGNETIC RESONANCE IMAGING FOR EVALUATION OF NAVICULAR SYNDROME IN THE HORSE

Radiographic evaluation of navicular syndrome is problematic because of its inconsistent correlation with clinical signs. Scintigraphy often yields false positive and false negative results and diagnostic ultrasound is of limited value. Therefore, we assessed the use of computed tomography and magnetic resonance imaging in a horse with clinical and radiographic signs of navicular syndrome. Cadaver specimens were examined with spiral computed tomographic and high-field magnetic resonance scanners and images were correlated with pathologic findings. Radiographic changes consisted of bony remodeling, which included altered synovial fossae, increased medullary opacity, cyst formation and shape change. These osseous changes were more striking and more numerous on computed tomographic and magnetic resonance images. They were most clearly defined with computed tomography. Many osseous changes seen with computed tomography and magnetic resonance imaging were not radiographically evident. Histologically confirmed soft tissue alterations of the deep digital flexor tendon, impar ligament and marrow were identified with magnetic resonance imaging, but not with conventional radiography. Because of their multiplanar capability and tomographic nature, computed tomography and magnetic resonance imaging surpass conventional radiography for navicular imaging, facilitating earlier, more accurate diagnosis. Current advances in imaging technology should make these imaging modalities available to equine practitioners in the future.