* * 规定，申请入党的同志，必须年满（）周岁。A．16 B．17 C．18 D．19

设集合P={1，2，3，4}，Q={x|x≤2，x∈R}，则P∩Q等于______．

戊型病毒性肝炎的传播途径是（）

A.消化道传播

B.呼吸道传播

C.经血传播

D.虫媒传播

如图甲所示，电阻不计，间距为l的平行长金属导轨置于水平面内，阻值为R的导体棒ab固定连接在导轨左端，另一阻值也为R的导体棒ef垂直放置到导轨上，ef与导轨接触良好，并可在导轨上无摩擦移动．现有一根轻杆一端固定在ef中点，另一端固定于墙上，轻杆与导轨保持平行，ef、ab两棒间距为d．若整个装置处于方向竖直向下的匀强磁场中，且从某一时刻开始，磁感应强度B随时间t按图乙所示的方式变化．

（1）求在0～t₀时间内流过导体棒ef的电流的大小与方向；

（2）求在t₀-2t₀时间内导体棒ef产生的热量；

（3）1.5t₀时刻杆对导体棒ef的作用力的大小和方向．

男，65岁，患急性胰腺炎入院，出现多器官功能不全综合征，分析其发生机制，不属于重要损害因子的是（）

A.细胞因子

B.炎性介质

C.生长因子

D.全身炎性反应

E.组织缺血-再灌注过程

Motherhood may make women smarter and may help prevent dementia in old age by bathing the brain in protective hormones, US reseachers reported on Thursday.

Tests on rats show that those who raise two or more litters of pups do considerably better in tests of memory and skills than rats who have no babies, and their brains show changes that suggest they may be protected against diseases such as Alzheimer’s. University of Richmond psychology professor Craig Kinsley believes his findings will translate into humans.

"Our research shows that the hormones of pregnancy are protecting the brain, including estrogen, which we know has many neuroprotective effects," Kinsley said.

"It’s rat data but humans are mammals just like these animals are mammals," he added in a telephone interview. "They go through pregnancy and hormonal changes. "

Kinsley said he hoped public health officials and researchers will look to see if having had children protects a woman from Alzheimer’s and other forms of age-related brain decline.

"When people think about pregnancy, they think about what happens to babies and the mother from the neck down," said Kinsley, who presented his findings to the annual meeting of the Society of Neuroscience in Orlando, Florida.

"They do not realize that hormones are washing on the brain. If you look at female animals who have never gone through pregnancy, they act differently toward young. But if she goes through pregnancy, she will sacrifice her life for her infant—that is a great change in her behavior that showed in genetic alterations to the brain. \

What can protect the brain of a woman according to the passage（）

A. Estrogen.

B. The hormones of pregnancy.

C. More exercise.

D. Taking care of children.