In Beijing, for example, the most common allergenic pollens in spring include those from the large-fruited elm tree, Cathay poplar, ash, acacia and white birch.

Partial Substitution of Hybrid Larch and Birch for Black Spruce TMP for the Production of Newsprint Grade

用落叶松和白桦代替部分黑云杉生产新闻纸用TMP

And the black dragon hill forest birch in young and middle aged forest harvesting and forest stand growth and structure were analyzed, mainly including: the average diameter of stand diameter structure, accumulation, spatial structure, etc..

并对黑龙山林场白桦中幼龄林采伐前后林分生长和结构差异进行分析，主要包括：林分平均直径、蓄积、直径结构、空间结构等。

The two differ, Luan of the first month forest farm forest more class, while the black dragon hill forest birch sapling forest maximum diameter is 9, and the tree numbers less.

两地不同之处在于，孟滦林场大阶级林木较多，而黑龙山林场白桦幼龄林最大径阶为9，且林木株数较少。

Black dragon hill forest birch sapling forest aggregation degree than Luan of the first month forest birch sapling forest aggregation degree is bigger.

黑龙山林场白桦幼龄林聚集程度比孟滦林场白桦幼龄林聚集程度较大。

The significant edge effect was found in Korean pine, white birch, black birch and aspen stands.

边缘效应表现显著的树种有红松、白桦、山杨和黑桦。

In all factors of vegetation structure characteristic, the average height of shrubs, the average canopy of trees and the average canopy of grass are difference factors in whole level, and the density of Black birch ( Betula dnvurica) is difference factor in specific composition level.

各样地的植被结构特征因子中，灌木平均高度、乔木平均盖度（郁蔽度）、草本平均盖度是各样地在总体水平上的差异因子，黑桦密度是样地树种组成水平上的差异因子；

This paper uses K-means, BIRCH and CURE respectively to cluster the log CT image data, and analyzes their characters in execution time, quality of clustering and sensitivity to the parameters.

分别用K-means，BIRCH，CURE对原木CT图像数据进行聚类，分析三者在聚类时间、聚类质量以及对参数的敏感程度的特征。

The C-13 and C-14 was showing me that paper birch and Douglas fir were in a lively two-way conversation.

碳13和碳14的流向告诉我，纸皮桦和花旗松之间的交流是双向的。

I grew 80 replicates of three species: paper birch, Douglas fir, and western red cedar.

那时我种了三种树，一共80棵：有纸皮桦、花旗松和西部红杉。

How were paper birch and Douglas fir communicating?

纸皮桦和花旗松到底是怎么交流的呢？

Birch of western United States resembling the paper birch but having brownish bark.

美国西部的一种桦树，类似于纸皮桦，但是树皮棕色。

The response of wood/ bark properties of red birch seedlings to elevated CO2 ( EC) under low ( LD) and high density ( HD) were investigated in closed top fumigation chambers ( CTC).

研究了高（HD）、低（LD）两个种植密度下红桦幼苗的树皮和去皮树干特征对CO2升高的响应。

The effects of elevated CO2 concentration on dry matter allocation and nutrient contents of red birch seedlings were studied under two planting densities in controlled environment chambers.

采用控制环境生长室研究了2个密度水平下CO2浓度升高对红桦幼苗干物质分配与营养的影响，并分析了红桦干物质分配与养分浓度的关系。

The results showed that red birch biomass was stimulated by CO2 enrichment, while the root to shoot ratio was not affected.

m-2两个密度水平。结果表明，升高CO2浓度可促进红桦幼苗生物量的增加，但对根冠比没有显著影响。

Response of dry matter allocation and nutrition of red birch ( Betula albosinensis) seedlings to elevated CO_2

红桦幼苗干物质分配与营养对CO2升高的响应

As a result, everyone from the John Birch Society to the Hells Angels may think we agree with them.

结果，每个来自约翰·伯奇协会的地狱天使们都可能认为我们在认同他们。

The induced eddy current in the iron core of iron style bipolar axial magnetic field vacuum interrupter is analyzed.

该文对铁芯式两极纵磁真空灭弧室中铁芯的涡流进行了数值分析。

Development and Study on iron core style bipolar axial magnetic field vacuum interrupter

铁芯式两极纵磁真空灭弧室的开发研究

These results differ from those for the bipolar background field case, in which the catastrophic energy threshold is almost independent of the magnetic fluxes of the flux rope and the extent to which the background field is open.

这与偶极场背景下的结果不同。在偶极背景场下，系统的灾变能阈与灾变点处磁绳的磁通和背景场的开放程度几乎没有关系。

The initial magnetic field is taken to be a force-free field, consisting of an isolated flux rope attached to the base and a bipolar background field surrounding it.

初始时背景场为无力场，磁绳附着于光球表面，外部为双极场。