2014年全国高职院校数量变化趋势及分类比较

随着高等职业教育的快速发展,我国高等职业院校数量已占据高等教育的半壁江山,在加快构建现代职业教育体系的背景下,保持并持续扩大高职院校数量规模对于实现这一目标具有重要意义。高等职业学校的数量,决定了高等职业教育的规模,了解中国高等职业院校整体在数量特征方面的发展态势和资源配置情况,有助于从整体上对高等教育宏观调控的把握。

Inhomogeneous trends in the onset date of extreme hot days in China over the last five decades

Using a homogenized daily maximum temperature(T_(max))dataset across China,this study characterized the spatiotemporal variation of the onset date of extreme hot days in a year(i.e.,FirstEHD)during 1960-2018.Inhomogeneous trends of FirstEHD over China during 1960-2018 can be found,with the advanced trend of FirstEHD over most parts in China,while a number of stations in North-Central China(NC)show the delayed trend of FirstEHD.Moreover,there exist interdecadal changes of FirstEHD trend,with a remarkable difference in the trend magnitude before and after the 1990s over South China(SC),and the sign of trend can even reverse from negative to positive after the 1990s in Xinjiang(XJ)and Yangtze River Basin(YR),and from positive to negative in NC.The overall trends of FirstEHD over NC,YR,and XJ during 1960-2018 are dominated by the trends before the 1990s,while they are dominated by the sharp advance after the 1990s over SC.It is further found that the trend of FirstEHD can generally be explained by the long-term trend in T_(max) over most parts of China,but the contribution from T_(max) variabilities is also non-negligible and can even account for more than 75% of the overall trend over NC.The possible factors responsible for the decadal changes in FirstEHD trends are also discussed.

A Preliminary Analysis of the Relationship between Precipitation Variation Trends and Altitude in China

Characteristics of the relationship between precipitation variation trends (PVT) and altitude were analyzed using monthly mean precipitation data from 526 observation stations in China from 1961 to 2008.With respect to elevation,China was divided into three subregions,below 200 m,200-1500 m,and above 1500 m.The results showed that the correlations between annual PVT and altitude are different among the three regions.In the region below 200 m in elevation,the best relationship has a correlation coefficient of-0.19 (0.49),passing the 90% (99.9%) significance level south (north) of 35 N.However,the correlation coefficient is close to zero,and the latitude strongly governs the spatial distribution of the amplitude of annual PVT in the 200-1500-m elevation region.In most of the Tibetan Plateau,where the elevation is greater than 1500 m,there is a weak negative correlation.The Mann-Kendall method was used to test the trend of regional mean annual precipitation,which indicated that the annual mean precipitation had no obvious trend of change in China due to the reverse significant variation trends in different areas of the country.

Characteristics of Spatial and Temporal Vegetation Index Variability and Its Responses to Temperature and Precipitation in Mongolia

The Mongolian Plateau,a vital ecological barrier in northern China,is of great importance for studying vegetation dynamics in Mongolia against the background of climate warming.Such studies can enhance our understanding of regional vegetation responses to global warming and contribute to the establishment of a stronger ecological barrier in northern China.Here,we analyzed the spatial and temporal characteristics of the NDVI(normalized difference vegetation index)in Mongolia using 8 km resolution GIMMS NDVI3g data from 1990 to 2022,along with temperature,precipitation,and elevation data.Trend analysis and correlation methods were used to examine the relationships between the NDVI and temperature,as well as precipitation.The results showed four important aspects of these relationships.(1)The NDVI in Mongolia increased significantly from 1990 to 2022 at a rate of 0.0015 yr^(-1)(P<0.05).(2)Mongolia’s NDVI increased from 1990 to 2022 in 60.73%of the country.Of this total,the area with a significant increase accounted for 31.67%and was concentrated on the eastern and western edges.The area experiencing a significant decrease accounted for 15.67%and was mainly located on the southwestern edges.(3)The NDVI analysis revealed significant increasing trends in all regions except for those at elevations of 1500-2000 m.The greatest rate of increase was observed between 500 and 1000 m,and the increasing trend weakened as elevation continued to increase before gradually becoming significant again.Additionally,the NDVI increased significantly across different slopes,and the rate of increase decreased as the slope increased.(4)From 1990 to 2022,Mongolia’s NDVI was mostly negatively correlated with temperature.This occurred over 66.75%of the total land area,with 17.21%of the region exhibiting a significant negative correlation,mainly in the southwest.Conversely,the NDVI demonstrated a positive correlation with precipitation,encompassing 86.71%of the total land area.Approximately 40.44%of the region had a significant positive correlation,primarily in the southwest.In conclusion,throughout the experimental period,the vegetation state in Mongolia improved.However,due to the warming and drying climate,more attention should be paid to vegetation degradation in the south-central region.