21g

The exo and endo reaction mechanisms of 1,3 - cyclohexadiene with propylene have been comprehensively studied by using ab initio method at 3 - 21G level .

采用从头算方法在3-21G基组上研究了1,3-环己二烯与丙烯生成exo和endo产物的反应机理。

In the vitro humman maligmant tumor specimen , the 20 , 21G needle had a 100 % success rate while the 22 G style had much lower success rate .

对离体的人体恶性肿瘤标本取材成功率，20、21G针为100%，22G针则明显降低。

A theoretical study of UV spectrum of Zn Al composite oxide was made utilizing an ab initio ( HF / 3 21G ) method . The relationship between UV spectrum and molecular structure was discussed .

利用量子化学的分子轨道理论，采用量子化学从头算法（HF/321G），对锌铝复合氧化物的紫外光谱特性进行了理论研究，圆满解释了锌铝复合氧化物紫外吸收性能与结构的关系。

Results One hundred and six biopsies were performed in the 69 lesions , the successful biopsy rate was 81 % ( 56 / 69 ) with 21G needles and 100 % with 18G needles .

结果69个病灶共进行了126次穿刺，21G活检针穿刺取材成功率为81%（56/69），18G活检针成功率为100%。

With respect to different needles , the definition of the tip of 14G RF needle was better visualized than that of 18G Bard and 21G PTC needles by using transparent maximal mode .

不同针具间，14G的RF针用透明成像的方式显示针尖优于18G的Bard针及21G的PTC针。

Objective : To initiate a new , safe and effective method for pathologic diagnosis of early pancreatic carcinoma by using the technology of US-guided percutaneous biopsy , and to compare the clinical usefulness of 18G core ( 18G ) needle and fine ( 21G ) needle in biopsy .

目的：通过超声引导穿刺活检技术的应用，为胰腺癌的早期病理诊断开创了一个安全有效的新途径，并比较18G粗针及21G细针穿刺活检的临床应用价值。

Methods Two canines were subjected to the injection of ozone oxygen gas ( 3ml with concentration of 30 μ g / ml ) into the L4 / 5 and L5 / 6 discs respectively with 21G Chiba needle . The procedure was repeated a week later .

方法选用2只实验犬的腰4/5和腰5/6椎间盘，以21GChiba针穿刺椎间盘中心部并向内注入3ml浓度为30μg/ml的臭氧&氧气混合气体，1周后重复1次。