The decrease of vegetation coverage was due to decline of herbaceous coverage. The threshold depth of groundwater level for coverage degradation was 4 m. This depth was the same as the depth of groundwater for degradation of species diversity.

Evolution of organic materials is divided into four stages according to total hydrocarbons/ organic carbon; the threshold depth and temperature for oil and gas formation are supposed to be at 2,200 meters and 90 ℃.

同时主要依据总烃/有机碳，将有机质演化划分为四个阶段，确定了油、气生成的起始门限：深度2200米，温度90℃。

Methods for determining maturation threshold depth of source rocks based on geochemical parameters of steranes and terpanes

根据萜烷、甾烷地球化学参数确定生油岩成熟门限的方法

The relationship between the hight of closure of the reservoir and threshold depth for oil generation is studied also.

在研究油藏封闭高度与生油门限关系时推论了油气运移途径及油气藏最后形成的时间问题。

This paper discusses some factors affecting oil-generation threshold depth of the Tertiary basins in East China.

进一步讨论了影响我国东部第三系含油气盆地成油门限值的几种地质因素。

On the basis of study on its sedimentary environment, sources and evolution characteristics of organic matter, this paper ensures the mature threshold depth and shows good prospects in oil and gas exploration in Hepu basin.

文章在研究其沉积环境、物源及有机质演化特征的基础上，确定该盆地成熟门限深度，表明合浦盆地具有良好的油气勘查前景。

The geological factors affecting the threshold depth of oil generation

影响生油门限深度的地质因素

Density evolution theory is specified and is applied to the analysis on the threshold of decoding, through which guidance can be provided to optimize irregular LDPC codes.

阐述了密度进化理论，并分析了译码过程中存在的阈值现象。然后介绍了密度进化理论在LDPC码优化方面的应用。

The Principle of Information Threshold Detection Decoding and Its Application in the Theory of Error Bound

信息门限判决译码原理及其在误差界限理论中的应用

The algorithm overcomes the threshold decoding algorithm shortcoming-too strict requirement for codes and narrow scope of application.

它克服了大数逻辑译码法存在的对码的要求过于严格，以及应用范围小的缺点。

The traditional decoding methods of convolutional code can be classified into two types: threshold decoding and probability decoding. The latter can be divided into sequential decoding and Viterbi algorithm.

卷积码的传统译码方法有两大类：一类是门限译码，另一类是概率译码，概率译码又分为序列译码和维特比译码。

Error Correct Threshold of Viterbi Decoder and Its Influence on Multiuser Detection

Viterbi解码器的纠错门限及其对多用户检测的影响

Low power design methods of setting threshold on viterbi decoder

Viterbi译码器设置门限的低功耗设计方法

The device has a reinforced ridge waveguide structure. The threshold current obtained at 80K is about 0 5A, and the corresponding threshold current density is about 5kA/ cm 2.

该器件具有增强型脊型波导结构，在80K时阈值电流为0.5A，相应的阈值电流密度为5KA/cm2。

Through the analysis of the loss and threshold characteristics of a laser diode ( LD), the threshold current density of LD with external feedback is calculated, according to the theory of multi-beam interference and the definition of equivalent reflection factor.

通过对半导体激光器（LD）的损耗和阈值电流特性的分析，引入等效反射系数的概念，根据多光束干涉的原理，导出了在外腔反馈作用下LD的阈值电流公式。

The doping concentration in the active region has great effect on the waveguide property. With the increasing of doping concentration, the waveguide loss, threshold gain and current density of THz QCL increase, the confinement factor decrease. 3.

结果表明，随着有源区掺杂浓度的提高，波导损耗增加，阈值电流增加，波导限制因子降低。

Calculated results show that when the Al-content of the waveguide and cladding layers are 0.4 and 0.5 respectively, a maximal output power of 11.2W, vertical divergence angle of 19 °, and threshold current density of 266A/ cm2 can be achieved by adapting narrow waveguide layers;

根据计算结果可知：当波导层和限制层铝组分为0.4和0.5时，采用窄波导结构可以获得器件的最大输出功率为11.2W，发散角为19°，阈值电流密度为266A/cm2；

Our analysis of one particular structure has shown that a relatively low threshold current density of 832A/ cm2 can provide a threshold optical gain of 50/ cm at room temperature. We have also found that the characteristic temperature in this structure is as high as 136K.

分析显示，用一个相对较低的阈值电流密度（832A/cm2）能够实现室温下产生50/cm的阈值光学增益，而且这种结构的特征温度高于136K。

Choosing three cases of Al-content of the waveguide layer and the cladding layer, we calculate and analyze the dependences of the optical confinement factor, maximal output power, vertical divergence angle, and threshold current density on the thickness of the waveguide layer.

选取了三种情况的波导层和限制层的铝组分，分别计算和分析了波导层厚度与激光器光限制因子、最大出光功率、垂直发散角和阈值电流密度的函数关系。

The experiments indicate that the use of source materials with high purity, BN effusion cells, and the cryopump in the system play important roles in reducing the threshold current density of the lasers and improving their optical and electrical performance.

实验表明，生长过程中采用高纯度的源材料，氮化硼的泻流盒以及生长系统中的低温泵等对降低器件的阈电流密度，改善激光器的光电性能起到重要作用。

The InGaAs/ GaAs strained quantum well lasers are able to work with extremely low threshold current density, high characteristic temperature and high COD limit, which make Ld lasers achieve higher output power and longer Ufe.

InGaAs/GaAs应变量子阱激光器具有级低的阈值电流密度、较高的特性温度和较高的光学灾变损伤阈值，这使得激光器具有更高的输出功率和更长的寿命。