限制因素

The virus is thought to have circulated for a month and disappeared. The source of the virus, the exact time of its introduction into Fort Dix, and factors limiting its spread and duration are unknown.

该病毒在传播了一个月之后消失，而该病毒的来源，何时传入迪克斯堡，以及限制它传播和存活的因素为何仍然还是个谜。

In fact, experience and experiment are used dominantly. But the empirical method is not always reliable because of its limited available range.

经验规律的可靠性受多方面因素的影响，有效适用范围常受较大限制。

The basal geomorphology structure of the Tidal-Basin System of the Tiaozini Sandbanks is watershed and tidal creek system. We analyses its formation, evolvement, geomorphology characters and development and discusses the main influence factors which is water, sediment and space. We divide the evolution phases which is formation phase, autumn phase and contabescence phase. In the end we confirms its main functions, which is discharging the folium water on the tidal flat of the Tidal-Basin in the end of the ebb-tide, transporting sediment to Tidal-Basin through tidal creek systems, confining the swing range of the dynamical axis of flood tide or ebb tide, balancing the dynamical status of the South and North. At the same time, we compare coastal tidal-basin and sandbanks tidal-basin on geomorphology characters, formation causes, style and so on.

条子泥潮盆—潮沟系统的基本地貌结构为分水滩脊和潮沟系统，本文分别对它们的形成与发育、地貌特点及动态变化进行了分析，并探讨了影响其发育的主要因素，即来水条件、来沙条件、空间条件，划定了其主要发育阶段，即形成期、成熟期、衰亡期；在上述分析的基础上确定了潮盆—潮沟系统的主要功能，即通过潮沟系统渲泄落潮后期滞留在其潮盆范围内的滩面薄层水、通过潮沟系向潮盆内部输入或输出泥沙、限制涨落潮动力主轴摆动范围、平衡南北两侧动力状态；同时针对岸滩潮盆—潮沟系统与沙洲潮盆—潮沟系统的地貌特征、成因类型等进行了对比分析。

The edge-crowding-effect of emitter current in a transistor caused by self-bias of base resistor is one of the factors to limit its capability of loaded current.

由基区电阻的自偏压引起的晶体管发射极电流集边效应，是限制晶体管承载电流能力的因素之一［1-4］。

This rarely happens, but there are other more practical limits to endurance, including the need to reset instruments and to remove the inevitable weed, barnacles and other marine life that would encrust a glider during very long voyages.

这极少发生，但是仍有更多其他的现实因素限制它的持久力，包括重新安排设备以及铲除不可避免的海草，在长期的航行中，藤壶和其他海洋生物可能依附其上，给它包上一层硬壳。

The relationship of productivity and the solar energy conversion efficiency which is one of the main limitations on productivity was discussed also.

文中也讨论了小球藻大规模培养中生长量以及限制生长量的主要因素与太阳能转换率之间的关系。

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。

Restricted by the exhaustibility of resources, together with high dependence on resources and single economic structure, resource-dependent mine areas are bound to meet with a series of problems when reaching certain stage of development.

资源型矿区由于受到资源有限性和不可再生的限制，加之资源型矿区发展对矿产资源的高度依赖性和经济结构单一性等因素，资源型矿区发展到一定程度就会面临一系列的问题。

Expansion of the family planning program.

你确信性别问题是限制家庭计划项目扩大的重要因素。

Note that the limiting factor here turns out to be the acoustic environment.

记下限制它们的因素，以弄清声学环境。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。