有环的

They can exist in a chain form or in a ring formed by reaction of the ketone or aldehyde group with an – OH group on one of the carbons at the other end of the chain.

它们有链式和环式。环式结构的形成是酮基或醛基与碳链另一端的羟基发生反应而相结合。

The metal winding filling piece, in the belt the outer ring winding filling piece, the flexible graphite seal ring, the octagonal pad, the ellipse planchet, the tooth profile pad, nearby the lens pad, the excel in package the filling piece, the asbestos rubber plate, can produce φ15-φ4000 the specification product

我们厂的主导产品有：金属缠绕垫片、带内外环缠绕垫片、柔性石墨填料环、八角垫、椭圆垫、齿形垫、透镜垫、高强包边垫片、石棉橡胶板、高强石墨复合板、蝶阀多层次密封材料、特制密封件产品，能够生产φ15-φ4000规格的产品。

Di-cyclopentadiene deserves to be mentioned for its simple decomposed product,cyclopentadiene,and its low-price.

尤其是双环戊二烯的分解产物单纯，仅有解聚后的环戊二烯一种，且价廉、易得，值得重视。

The molecule of taxol is an extremely complex diterpene with a taxane ring structure fused with a four-membered oxetane ring, an ester side-chain at position C-13 and a benzoyl side-chain at the C-2 position Fig.

紫杉醇分子是一个极其复杂的四环二萜类化合物：一个紫杉烷环加一个四个元素组成的氧烷环，在C-2和C-13上还分别有一个苯氧基和酯基侧链。

It was also found that the electron-donating groups in the 5-position of indoline moiety could stabilize the colored forms and then low the thermal decay date.

吲哚啉环上5位的取代基对螺噁嗪热消色过程也有影响。5位的给电子基团能稳定开环体，热消色速率降低，寿命延长。

The experiments of the biological activity for target molecula were accomplished. The experiment results of inhibiting activity against COX-2 indicated that the compound TM-II-5f had the highest inhibition rate, up to 95.59%, and yet the compound TM-II-5g exhibits weakly inhibiting activity.

对目标产物TM-II-5a~5g进行了生物活性研究，人环氧酶-2(COX-2)活性抑制实验结果表明：目标产物TM-II-5f对人环氧酶-2(COX-2)有很强的抑制活性，抑制率高达95.59%，目标产物TM-II-5g具有较弱的抑制率(0.61%)。

The contrast experiment shows that the d90 temporary plugging technology presents the best pretection effect,which shield ring intensity is more than 25MPa, the flowback recuperability of the permeability can attain 97.2%, and the shield ring intensity is more than 15 MPa.

进行的对比实验表明，运用&理想充填&理论和&d90&暂堵技术与传统屏蔽暂堵技术相比，&d90&技术对储层有更好的保护效果。该技术对于孔隙性储层屏蔽环强度大于25MPa，渗透率返排恢复率最高能达到97.2%；裂缝性储层屏蔽环强度大于15MPa。

In the central region the N_1-P and P-N_2 amplitudes of mfVEP of the inisometropic amblyopic eyes were reduced compared with the normal eyes.2. In strabismic amblyopia eyes and anisometropic amblyopic eyes the latencies of mfVEP were markedly prolonged.

斜视性弱视和屈光参差性弱视的mfVFP特征峰潜时在各环都较对侧眼和正常对照组延长；屈光不正性弱视患者的特征峰潜时在各环较正常对照组延长，其差异均有统计学意义。

From its roots, we gained 9 compounds including triterpenes, steroidal glycoside, and fatty acid, a triterpene and a of them are new compounds.

分别对肥牛树的根、茎、叶三个部分的乙醇提取物进行了提取分离工作，从其根中分离鉴定了9个化合物，包括三萜、甾醇苷、酚性化合物、螺环化合物和脂肪酸等，其中有两个新化合物，即一个三萜和一个螺环化合物。

The shell roof of steel structure on the site of Jinsha in Chengdu is the truss structure with unstiffen tubular joints ,and the chords of circumferential truss are irregular space curves.

成都金沙遗址大棚钢结构工程为圆钢管相贯节点桁架结构，环桁架弦杆为不规则空间曲线，通过采取弯管与胎具双重控制的方法，使环桁架尺寸得到精确控制；由于施工条件限制，采取了钢丝绳加固、结合已有结构辅助的方法将平面桁架移动到指定位置。

Finally, according to market conditions and market products this article paper analyzes the trends in the development of camera technology, and designs a color night vision camera.

最后根据市场情况和市面上产品的情况分析了摄像机技术的发展趋势，并设计了一款彩色夜视摄像机。

Only person height weeds and the fierce looks stone idles were there.

只有半人深的荒草和龇牙咧嘴的神像。