促进多巴胺能神经末梢释放DA的是( )。 A．左旋多巴 B．金刚烷胺 C．苯海索

为考核口服痢疾弧菌疫苗预防细菌性痢疾的效果，将1000名研究对象随机分成疫苗组和对照组，两组分别500人。以血清抗体的阳转和细菌性痢疾发病率的下降为结局变量指标，随访观察2年时间。研究结果表明，疫苗组的痢疾杆菌抗体阳转者450人，对照组的抗体阳转者50人；疫苗组发生细菌性痢疾病人15人，对照组发生细菌性痢疾病人60人。

下列不是经食物传播传染病的流行病学特征的是（）

A.不食者不发病

B.病人有进食某一食物史

C.传播广泛、传播途径易实现、发病率高

D.一次大量污染可致暴发

E.停止供应污染食物后，暴发可平息

后牙接触前牙不接触需调整哪个因素

A．前牙覆盖
B．降低胎平面
C．横骀曲线
D．都需要
E．前牙覆牙合

严格定义的方法有假设前提，下列有( )假设属于它。 Ⅰ．所有需求都能被预先定义 Ⅱ．周期各阶段都固定正确 Ⅲ．大量的反复是不可避免的 Ⅳ．有快速的系统建造工具

A．Ⅰ

B．Ⅱ

C．Ⅰ、Ⅱ

D．Ⅲ、Ⅳ

阅读理解。

     New findings from Queen's University biologists show that in the plant world, bigger isn't

necessarily better.

     "Until now most of the thinking has suggested that to be a good competitor in the forest,

you have to be a big plant," says Queen's Biology professor Lonnie Aarssen. "But our research

shows it's virtually the other way around."

     Previous studies showed that larger plant species monopolize(垄断) sunlight, water and

Other resources, limiting the number of smaller plant species that can exist around them. But

the research has proved that this is not generally the case in natural vegetation.

     In the Queen's project, PhD student Laura Keating targeted the largest "host plants" of 16

woody plant species growing in the Okanogan Valley, British Columbia. The research team

calculated the number and variety of plants that neighbored each large host plant. They then

randomly selected plots without host plants and calculated the plant species there as well. The

research showed that the massive trees have no effect on the number of species with which they

coexist.

     Smaller plants have many advantages over their overbearing neighbors, Professor Aarssen

notes. Larger species generate physical space niches(生态位)under their shelters where smaller

species grow well. Smaller plants are much more effective than large trees at using available

resources. They also produce seeds at a much younger age and higher rate than their bigger

counterparts, and settle down much more quickly-thus competing with the newly-born plants

of larger species.

1. What's the main idea of the text?

A. Smaller plants may have many advantages over their neighbors.

B. In the plant world, the bigger is better than the smaller one.

C. To be a good competitor in the forest, you have to be a small plant.

D. Queen's University's students made a new research.

2. The underlined word "this" in Para.3 refers to the view that ____.

A. large and small plants can grow together in harmony  

B. larger plant species limit their smaller neighbors' growth

C. small plant species have their own advantages

D. large and small plant species can never coexist.  

3. What does the underlined word coexist mean in paragraph 4?

A. cooperate together  

B. surround together  

C. evolve together  

D. live together

4. Which is the CORRECT order in the Queen's project?

a. Randomly selected plots without host plants and-calculated the plant species.

b. Calculated the number and variety of plants that neighbored each large host plant.

c. Selected the largest individuals or "host plants" of 16 woody plant species.

A. a, b, c          

B. c, b, a        

C. b, c, a        

D. a, c, b

5. What can we learn according to the text?

A. Larger plant species limit the number of smaller ones around them.  

B. Smaller plants can limit the number of plant species around them.

C. Smaller plants produce seeds at a higher rate than their bigger counterparts.

D. Larger trees are more effective than small plants at using available resources.

为防止创业企业控制权的旁落，创业者可以采取的事后措施，包括（）。

A.按比例增资或减资

B.实施股份的优先购买权

C.明确在分立或合并后的企业中的股权和地位

D.如果是上市公司，可采取毒丸计划、金降落伞计划等防御措施