根的

1H NMR spectroscopic analysis of aromatic protons combined with theoretical analysis of molecular structures proved the existence of two rotational isomers at 300 K, as well as a rapid interconversion equilibrium at 330 K for both compounds Ⅰ and Ⅱ. However, only one conformer exists for compound Ⅲ and puerarin containing 7-phenolic hydroxyl instead of propyl in A-ring as the case of compounds Ⅰ and Ⅱ. Based on UV-Visible absorption data of neutral and basic solutions, and on the density function calculations, the 7-phenolic hydroxyl group in A-ring was found to be more acidic than the 4'-phenolic hydroxyl group in B-ring. The mechanism of derivation reaction and the structure-reactivity relationship of puerarin as an antioxidant were further discussed.

其中7-丙基葛根素Ⅱ属于新型取代衍生物；变温1H NMR和理论计算结果表明，在300 K时，葛根素和4'-丙基葛根素以单一构型存在；而7，4'-二丙基葛根素和7-丙基葛根素则存在两种核磁可分辨的旋转异构体，当温度升至330 K时，两种异构体可以相互转化；通过对比分析葛根素及其衍生物脱质子产物的紫外可见吸收光谱并结合理论计算，确定了A环上7位酚羟基比B环上4'位酚羟基先脱去质子，并由此进一步阐明了葛根素衍生化反应机理以及在抗氧化作用中可能的活性位点和结构活性关系。

METHODS:Fifty two permanent maxillary first molars,which were diagnosed as pulpitis and periapical periodontitis clini cally,were selected.The pulp chamber floors were examined and detected to locate the mesiolingual canals(MB2) by naked eyes and SOM respectively.

由于其近颊根通常有近中颊和近中舌(MB2 ) 2个根管，而其近中舌根管细小且根管口常较为隐蔽，因此，Weine认为上颌第一恒磨牙根管治疗失败的一个主要原因是治疗中遗漏了MB2根管。

When earlier place upside still does not have apparent symptom, root ministry grows to already was affected, radicle root needle grows stop, and cerebral cortex continues to add thick, in close root needle section chief gives very much new root, serious Shi Yougen dies, typical symptom is long around dead root piece short thick and much more ramose root group.

初期当地上部还无明显症状时，根部生长已受到影响，幼根根尖生长停止，而皮层继续加厚，在近根尖处长出很多新根，严重时幼根死亡，典型症状是在死根四周长出短粗且多分枝的根群。

Ss group was by prepared by k-files with step-back technique. all canals were obturated using lateral condensation technique.

将245颗具弯曲根管需行根管治疗的磨牙随机分为两组，he组用hero642镍钛锉及冠根向深入法预备根管，ss组用k锉及逐步后退技术预备根管。

The experiment of the auxiliary heated arc plasma generator shows that thekey arc root has contraction under the condition of having magnetic field when thekey arc root is at the edge of the cathode surface.

在辅助加热电弧等离子体发生器的实验中看到：在有外磁场的情况下，主弧弧根在阴极边缘时，弧根有收缩的迹象，而当主弧弧根在阴极中心附近时，观察不到明显的弧根收缩迹象，并拍摄到有双弧柱的图片；当关掉磁场和弧电流〓时，主弧在阴极和阳极之间稳定的燃烧，主弧弧根稳定在阴极中心附近的一点上，而且弧根没有收缩的迹象，主弧弧根亮区的直径约为6.8毫米，与弧柱段的亮区直径相差无几；因而从实验结果分析可以看出，阴极表面温度的升高，能使主弧弧根直径增大：另一方面，由于主弧弧根直径的增大(即也意味着主弧弧根截面积的增大)，因而使电弧通过主弧弧根传入阴极表面的有效比热流降低，从而减少了阴极烧损。

The method locates with Raypex5 root needle appearance has a tooth to 205 in all 403 roots canal undertakes length of root canal job is measured, after undertaking with this length the root is in charge of provision to fill up, film X line piece the quality that observes root canal fills up.

方法用Raypex5根尖定位仪对205颗患牙共403个根管进行根管工作长度测量，以此长度进行根管预备充填后拍摄X线片观察根管充填的质量。

When pulp chamber access were achieved, the working length of each canal was measured using ROOT ZX apex locator with root canals in dry or moisture conditions.

常规根管清理后，采用ROOT ZX根管长度电测仪在干、湿两种根管状态下进行根尖位置的探测，根管充填后，根据X线片影像确定根管长度电测法的准确性。

METHODS: 8 curved artificial root canals were prepared with stainless steel K files by the step-back technique, the root canals were digitally photographed, the images were analysed by the software Image-Pro Plus, the shapes and positions of the root canals were measured and analysed. SPSS10.0 software package was used for statistical analysis, paired-samples t test was used to compare the difference of the means among sample groups.

使用手用不锈钢K锉，按逐步后退法预备8个弯曲人工根管，根管预备过程中对根管及根尖孔进行微距摄影，用图像分析软件Image-Pro Plus对根管的形态与位置变化进行测量、分析；实验数据采用SPSS10.0统计软件包进行统计学分析，选用配对t检验比较组间差异。

objective to evaluate clinical effect of the handling protaper nickel-titanium rotary instruments in preparation of canals of posterior teeth.methods 96teeth with pulpitis or periapical periodontitis were instrumented by handling protaper rotary instruments using step-down technique,and by k files using step-back technique for control.all teeth were obturated with lateral condensation methods.the efficiency of preparation was analyzed with ra-diographs before and after operation.results no transportation,apical blockage and ledge were found in test.the technique could keep canals smooth.there were two ledge,one instrument fracture and nine transportation in control.the operative time was shorter and post treatment pain seldom occurred in handling protaper group.conclusion the handling protaper niti rotary instruments can prepare the canals effectively and safety.after the preparation,the canals could be easily washed,sterilized and filled.it is an efficient instrumentation method for posterior teeth's canals and be used widely.

目的 评价手用protaper预备后牙根管的临床效果。方法选取患有牙髓炎和根尖周炎的后牙96例，随机分成试验组和对照组各48例，试验组用手用protaper多锥度镍钛旋转器械逐步伸入法预备根管，对照组用k锉，逐步后退法预备根管，两组均用侧向加压充填法充填根管，根据治疗前后的x线片，评价后牙根管预备效果。结果试验组无根管偏移、根尖阻塞、台阶，且根管壁平滑流畅，无器械折断等并发症发生。对照组有2例台阶形成，器械折断1例，根管偏移9例。试验组操作时间短且术后疼痛轻微。结论应用手用protaper预备后牙根管快速、安全，成形效果好，易于根管冲洗消毒及填充，可视为临床上预备后牙根管的有效方法。

The country produced its own independent intellectual property rights of patent products -- Bergen plates embedded Lining Plastic Pipe tendon. Bergen licensing double stainless steel-lined metal, reinforcement plates embedded Bergen double Lining Plastic Pipe, Bergen-licensing Lining Plastic Pipe condensation. Bergen licensing steel skeleton reinforced composite plastic screen to five types of products.

公司生产拥有独立知识产权的国家专利产品——贝根牌内筋嵌入式衬塑钢管、贝根牌钢衬不锈钢双层金属管、贝根牌内筋嵌入式双面衬塑钢管、贝根牌缩合式衬塑钢管、贝根牌钢丝网骨架增强复合塑料管等五大类产品。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。