必要条件

RESULTS:After pinealectomized mice was irradiated WBI with 75 mGy X-rays,we found levels of plasma corticosterone increased obviously,and the effects of the proliferative reaction of splenocytes to ConA and spontaneous proliferation of thymocytes was found to be decrease. But injecting melatonin into pinealectomized mice or putting melatonin in the cultured cell,its immune functions might renew the enhancement.CONCLUSION:Melatonin of pineal gland might regulate the immunoenhancement induced by low dose radiation.MeSH Pineal body; Melatonin; Radiation; Corticosterone; Immunity,cellular

低剂量辐射(low dose radiation，LDR)全身照射(whole body irradiation，WBI)可引起免疫系统的兴奋效应，主要表现在以T淋巴细胞功能激活为主的细胞免疫和体液免疫功能的增强并可提高机体的抗瘤作用［4，5］，在LDR诱发免疫功能增强的同时伴有下丘脑-垂体-肾上腺皮质系统功能下调等神经内分泌功能的改变，神经内分泌对免疫系统的调节可能是LDR免疫兴奋效应发生的必要条件，松果腺MLT与辐射免疫兴奋效应的关系值得研究。

In addition, we prove that for a given set of camera motions such as {(R,t1),(R,t2)},if (t1 ,t2) are not linearly dependent, then the homography of the plane at infinity under this motion set can be linearly and uniquely determined.

另外同时给出了由极点确定关于无穷远平面单应性矩阵的充分必要条件。

The polar body extrusion process of induced maturation is similar to naturally fertilized eggs.

在卵母细胞成熟过程中有受精膜举起的现象，说明精子入卵不是受精膜举起的必要条件。

The necessary conditions and sufficient conditions for a set to be polar are listed.

具体内容如下：·研究了N指标d维广义Brownian Sheet的极集的性质，得到了其极集的必要条件与充分条件。

Zeros of linear polynomials with real efficients are the real solutions of the original polynomial equation.

5四元数二次方程的显式解：利用改进的新方法完全可以得到二次方程解的显式表示以及关于解的具体情况的一些充分必要条件。

In the study of open-loop optimal control problems, a useful tool is the so-called "Pontryagin"s Maximum Principle which gives a set of necessary conditions to optimal open-loop controls.

对于开环控制的研究，在最优控制理论中已经有了Pontryagin最大值原理这个有效的工具，它提供了最优开环控制的一个必要条件。

Under some proper conditions we prove the existence of optimal controls in the class of Lipschitz functions, and obtain an optimality condition looks somehow like Pontryagin's maximum principle for a smooth optimal control function.

在适当的假设条件下，我们证明了状态方程解的存在唯一性和最优控制的存在性；并且根据最有控制函数的光滑性进一步对最优化存在的必要条件进行分析。

By using the Li e group theory of differential geometry and Pontryagin's maximum principle, it is pointed out that the mobile CRS robot on surface is controllable, and the nec essary conditions and the structure equations of extremal trajectories are propo sed.

为了解决曲面上移动CRS机器人的路径规划问题，在曲面上建立了机器人的动态模型，利用微分几何的李群理论和庞特里亚金最大值原理，证明了曲面上CRS机器人是可控的，并给出了机器人的最小时间控制的必要条件和结构方程。

Having extensive masses base is to make sure the Communist Party is in office positional requirement.

具有广泛的群众基础是保证共产党执政地位的必要条件。

Memory is the continuation of psychology in time, as well as a pre-requisite for the cultivation of psychology, mentality and personality.

记忆，是心理在时间上的持续，是心理发展、感情和意志培养的必要条件。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。