必不可少

The author uses the communication mechanism in Aglets system to achieve Agent communication.6 To ensure the normal operation of the system, monitoring and error detection is an essential component of the system.

为了保证体系正常运行，监控和异常处置是体系必不可少的组成部门。

Compared with classical cytotoxic T lymphocytes , NK cells are superior in the following aspects: NK cells are among the first cell types to be activated after intracellular pathogen stimuli, the activity of NK cells peaked between 1 to 3 days, retained during the first 7-10 days, and the T cells response emerged only after 7 days when the NK cell responses begin to decline; though comprising of only 10％-15％ of peripheral lymphocytes, NK cells mobilize most of the cell populations in a strong and high level response to different invasions, and act as key factors at early defense before a specific immune response could mount, while only certain clones were involved in T cell response; NK cells kill virus-infected or malignant transformed cells without pre-sensitization and without restriction by major histocompatibility antigen, which is usually a mechanism of immune escape to T cell recognition by virus-infected or tumor cells, thus NK cell in complementary with T cells play crucial roles in tumor and virus eradication.

NK细胞以其强大的细胞毒活性为特征，与细胞毒性T细胞相比，NK细胞具有如下特点：NK细胞虽然只占外周血淋巴细胞的10-15％，但是对刺激性因素产生应答的过程十分迅速，一次可以调动大多数细胞共同参与，而不是几个克隆的活化，免疫应答的强度高；病毒感染或恶性转化细胞的一个主要特征是细胞表达的MHCⅠ类分子下降或消失，并借助这一机制逃避特异性T细胞应答的识别，NK细胞介导的杀伤活性无需抗原刺激，不受MHCⅠ分子表达的限制，从而与T细胞应答互为补充发挥免疫防御的功能；NK细胞的免疫活性可以被多种细胞因子上调，其中IFNα，IL-2，IL-12，IL-15和IL-18具备更强的作用；NK细胞具有强大的细胞因子分泌功能，对于启动T细胞特异性应答必不可少。

It is necessary to have a meeting ,especially when you won't work.

开会是必不可少的，尤其是在你不想工作的时候。

Time is one of the basic physical attributes of the world we live in. The accurate time not only gives an essential parameter to science research and experiments and engineering technologies, but works as an indispensably ruler for all dynamics systems and sequential procedure.

时间是物质运动和存在的基本属性之一，精密的时间作为科学研究、科学实验和工程技术诸方面的基本物理参量，为一切动力学系统和时序过程的测量和定量研究提供了必不可少的时基坐标。

I hope that the message of the artwork becomes the essential point.

我希望这副艺术作品所传达的信息可以成为必不可少的基点。

Hope you enjoy it and don't forget to read the 15 essential tips on power point 2007 tips ...

希望您会喜欢它，并没有忘记阅读15必不可少的秘诀2007年功率点提示。。。

Statistical thinking and methods are essential to a broad spectrum of industrial, research, educational, business, and government activities.

统计思想和方法是必不可少的工业，科研，教育，广泛的商业和政府活动。

As more and more British companies now find that a China strategy is an essential part of their global strategy, the Chamber's work has become more important than ever before.

随着越来越多的英国企业认识到，中国战略是自己全球战略中一个必不可少的组成部分，英国商会的工作也比以往任何时候都重要。

With the gradual integration of the global economy development and deepening of the online bookstore has become a traditional bookstore, one of essential business strategy.

详细说明：随着全球经济一体化的逐步发展和深入，网上书店已成为传统书店必不可少的经营策略之一。

I think that money is essential to life and we cannot do without money.

我认为钱是必不可少的生活，我们不能没有钱。

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。