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1.
The Northeast China Transect (NECT) along a precipitation gradient wasused to calculate the carbon balance of different vegetation types, land-use practices and temporal scales. NECT consists of mixed coniferous-broadleaved forest ecosystems, meadow steppe ecosystems and typical steppe ecosystems. Analyses of the C budget were carried out with field measurement based on dark enclosed chamber techniques and alkali absorption methods, and the application of the CENTURY model. Results indicated that: (1) soil CO2 flux had a strong diurnal and seasonal variation influenced by grassland type and land-use practices. However, the seasonal variation on soil CO2 fluxes did not show obvious changes between non-grazing and grazing Leymus chinensis dominated grasslands. (2) Hourly soil CO2 fluxes mainly depended on temperature, while daily CO2 fluxes were affected bothby temperature and moisture. (3) NPP of the three typical ecosystems showed linear relationships with inter-annual precipitation, but total soil carbon of those ecosystems did not. NPP and total soil carbon values decreased westward with decreasing precipitation. (4) Model simulation of NPP and total soil carbon showed that mean annual precipitation was the major limiting factor for ecosystem productivity along NECT. (5) Mean annual carbon budget is the largest for the mixedconiferous- broadleaved forest ecosystem (503.2 gC m-2 a-1), followed by the meadow steppe ecosystem (227.1 gC m-2 a-1), and the lowest being the typical steppe ecosystem (175.8 gC m-2 a-1). This study shows that concurrent field measurements of terrestrial ecosystems including the soil and plant systems with surface layer measurements along the water-driven IGBP-NECT are valuable in understanding the mechanisms driving the carbon cycle in different vegetation types under different land-use practices. Future transect research should be emphasized.  相似文献   

2.
野外调查与历史资料相结合,对内蒙古锡林河流域一个永久试验样地内的羊草( Leymus chinensis (Trin.) Tzvel.)草原群落(原生草原群落)的碳素贮量、主要流量和周转速度等进行了估计.结果表明:1)该群落中地上部净初级生产的碳素固定量的多年平均值为79.8 g C*m-2*a-1,根系碳素输入量的多年平均值为311.9 g C*m-2*a-1,碳素输入总量为391.7 g C*m-2*a-1; 2)土壤净呼吸量为346.9 g C*m-2*a-1,动物(昆虫)采食量14.7 g C*m-2*a-1,地上立枯阶段的淋溶与光化学分解损失为3.2 g C*m-2*a-1,碳素输出总量为364.8 g C*m-2*a-1; 3)该群落中碳素输入略大于输出,净积累速率为26.9 g C*m-2*a-1,0-30 cm土壤中的碳素周转速率为6.2%,周转时间为16年.  相似文献   

3.
 野外调查与历史资料相结合,对内蒙古锡林河流域一个放牧羊草(Leymus chinensis)草原群落的碳素贮量、主要流量和周转速度等进行了估计,在此基础上对放牧情况下该群落的碳素收支进行了概算。结果表明:1)该群落中地上部净初级生产固碳量的两年平均值为78.2 gC·m-2·a-1, 根系碳素输入量的平均值为322.5 gC·m-2·a-1, 碳素输入总量为400.7 gC·m-2·a-1; 2)土壤净呼吸量为343.7 gC·m-2·a-1,家畜采食量为49.7 gC·m-2·a-1,动物(昆虫)采食量为14.7 gC·m-2·a-1,地上立枯阶段的淋溶与光化学分解损失为3.2 gC·m-2·a-1,碳素输出总量为411.3 gC·m-2·a-1; 3)该群落中碳素输出略大于输入,净释放速率为10.6 gC·m-2·a-1,0~30 cm土壤中的碳素周转速率为6.2%,周转时间为16年。  相似文献   

4.
利用CENTURY模型对内蒙古锡林河流域羊草草原在未来气候变化以及大气CO2浓度增高条件下的年地上净初级生产力(annual aboveground net primary productivity,ANPP)动态进行了模拟研究.结果表明:CENTURY模型可以较好地预测ANPP的变化.进一步的情景模拟发现,虽然全球气候变化所引起的温度和降水改变、以及大气CO2浓度升高都会影响ANPP,但降水是关键的影响因子.多个全球气候模型(GCM) 预测该地区未来降水量会减少,故可能导致其ANPP降低,但在以下气候变化情景下研究区ANPP可能会升高:1)CO2浓度倍增,温度升高2 ℃,降水保持不变或增加10%~20%;2)CO2浓度保持不变,温度升高2 ℃,降水增加20%.气候变化将对内蒙古锡林河流域羊草草原产生显著影响.  相似文献   

5.
Carbon balance along the Northeast China Transect (NECT-IGBP)   总被引:6,自引:0,他引:6  
The Northeast China Transect (NECT) along a precipitation gradient was used to cal-culate the carbon balance of different vegetation types, land-use practices and temporal scales. NECT consists of mixed coniferous-broadleaved forest ecosystems, meadow steppe ecosystemsand typical steppe ecosystems. Analyses of the C budget were carried out with field measurement based on dark enclosed chamber techniques and alkali absorption methods, and the application of the CENTURY model. Results indicated that: (1) soil CO_2 flux had a strong diurnal and seasonal variation influenced by grassland type and land-use practices. However, the seasonal variation on soil CO_2 fluxes did not show obvious changes between non-grazing and grazing Leymus chinensis dominated grasslands. (2) Hourly soil CO_2 fluxes mainly depended on temperature, while dailyCO_2 fluxes were affected both by temperature and moisture. (3) NPP of the three typical ecosys-tems showed linear relationships with inter-annual precipitation, but total soil carbon of those eco-systems did not. NPP and total soil carbon values decreased westward with decreasing precipita-tion. (4) Model simulation of NPP and total soil carbon showed that mean annual precipitation was the major limiting factor for ecosystem productivity along NECT. (5) Mean annual carbon budget is the largest for the mixed coniferous- broadleaved forest ecosystem (503.2 gC m~(-2)a~(-1)), followed bythe meadow steppe ecosystem (227.1 gC m~(-2)a~(-1)), and the lowest being the typical steppe eco-system (175.8 gC m~(-2)a~(-1)). This study shows that concurrent field measurements of terrestrial ecosystems including the soil and plant systems with surface layer measurements along the wa-ter-driven IGBP-NECT are valuable in understanding the mechanisms driving the carbon cycle in different vegetation types under different land-use practices. Future transect research should be emphasized.  相似文献   

6.
于 1999年生长季对内蒙古锡林河流域主要类型草原土壤中 CH4和 CO2 浓度进行测定 ,结果表明 :CH4浓度沿土壤剖面逐渐降低 ,而且不同土壤深度之间差异显著 ,而 CO2 浓度呈现出沿土壤剖面增加的趋势。草甸草原、羊草 (L eymus chinesis)草原和大针茅 (Stipa grandis)草原土壤中 CH4的浓度差异显著 ,季节变化明显 ,但是三类草原土壤中 CO2 浓度变化不大。测定结果还表明 :一定时间尺度上 ,放牧对草原土壤中 CH4和 CO2 的浓度没有显著影响。  相似文献   

7.
采用碱液吸收法对锡林河流域一个半干旱典型草原群落的土壤呼吸进行了5个月的野外测定,并对其与气候因子和生物量之间的关系进行了分析.另选择了锡林河岸边的一个沼泽化草甸群落作为对比来研究土壤湿度和植被类型对土壤呼吸的影响.主要结果包括:1)两个群落土壤呼吸的季节动态基本一致,均出现了两个峰值,其中草原群落和草甸群落土壤呼吸速率的变化范围分别为312.8~1 738.9mgC@m-2@d-1和354.6~2 235.6 mg C@m -2@d-1.草甸群落的土壤呼吸速率明显高于草原群落,它们的日平均土壤呼吸速率分别为1 349.6 mg C@m-2@d-1和785.9mg C@m-2@d1;2)在草原群落中,土壤呼吸速率与土壤湿度的相关性比其与温度的关系更加显著,而在草甸群落正好相反,反映出这两种气候因子在不同生境中起着不同的作用.根据土壤呼吸与气温之间的同归关系外推出2001年生长季草原群落和草甸群落的土壤呼吸量分别为142.4 g C/m2和236.1 g C/m2;3)在草甸群落中,地上总生物量与土壤呼吸速率之间没有显著的相关关系,而地上部活体生物量与土壤呼吸速率之间则存有很显著的幂函数关系.在草原群落中,土壤呼吸速率与地上活体生物量或地上总生物量的相关性均很弱.  相似文献   

8.
鲍雅静  李政海 《生态学报》2008,28(9):4540-4546
植物功能群(plant functional groups, PFGs) 是具有确定的植物功能特征的一系列植物的组合,是生态学家为研究植被对气候变化和干扰的响应而引入的生态学概念.目前功能群研究中最核心的问题仍在于决定植物功能群划分的植物特征的选择上.以内蒙古锡林河流域草原植物群落为例,选取3个草原类型(羊草草原、大针茅草原和羊草草甸草原)及其退化梯度系列(未退化、轻度退化、中度退化、重度退化),在对植物热值进行分析测定的基础上,依据植物的能量属性-单位重量干物质在完全燃烧后所释放出来的热量值,采用人为分段的方法对草原植物进行了能量功能群的划分(高能值植物功能群、中能值植物功能群和低能值植物功能群).并探讨了这种能量功能群划分方法在草原植被动态研究中的客观性与可行性.  相似文献   

9.
 于1999年生长季对内蒙古锡林河流域主要类型草原土壤中CH4和CO2浓度进行测定,结果表明:CH4浓度沿土壤剖面逐渐降低,而且不同土壤深度之间差异显著,而CO2浓度呈现出沿土壤剖面增加的趋势。草甸草原、羊草(Leymus chinesis )草原和大针茅(Stipa grandis)草原土壤中CH4的浓度差异显著,季节变化明显,但是三类草原土壤中CO2浓度变化不大。测定结果还表明:一定时间尺度上,放牧对草原土壤中CH4和CO2的浓度没有显著影响。  相似文献   

10.
This paper deals with light-photosynthesis curve, temperature-photosynthesis curve, diurnal changes of photosynthesis, and effects of water content and nitrogen in soil on photosynthetic characteristics of leaves of Leymus chinensis. The results obtained are as follows: 1. Light-photosynthesis curve of Leymus chinensis approximates to a hyperbola below light saturation point, and the influence of light intensity on photosynthesis is expressed by light intensity coefficient of photosynthesis. When Leymus chinensis was grown in a good water condition, its light intensity coefficient was 1.33 mg CO2· dm-2· h-1 · klx-1 at 5 klx light intensity, and light saturation point was 50 klx, and net photosynthetic rate at light saturation condition was about 31 mgCO2 · dm-2 · h-1. Temperature-photosynthesis curve of Leymus chinensis was a parabola, and optimum temperature of photosynthesis was 26–29 ℃. CO2 compensation point of Leymus chinensis was about 35 ppm. According to aforesaid characteristics of photosynthetic ecology, Leymus chinensis is a sun plant of C3 type. 2. The curve of diurnal changes of photosyn thesis in Leymus chinensis shows as a two-peak type in typical steppe, when water content of soil is about 14%. Major ecological factor which caused midday depressing photosynthesis in Leymus chinensis is atmospheric humidity. 3. The photosynthetic characteristics of Leymus chinensis, especially the leaf area and aerial biomass are closely related with water and nitrogen in soil. Irrigation has greater influence on photosynthetic production as compared with fertilization. The efficiency of increasing production is more notable, combining the measures of irrigation with fertilization. Leymus chinensis may be regarded as a eurytopic xerophyte according to the relationship between some photosynthetic characteristics and soil water. 4. Compared photosynthetic rate with leaf area in Leymus chinensis, the influence of the leaf area change on photosynthetic production is greater and is more remarkable during arid conditions. Therefore, irrigation and fertilization during dry season are effective measures to develop photosynthetic organ and to raise aerial biomass of Leymus chinensis rapidly.  相似文献   

11.
We examined the long-term dynamics of plant biomass of Filifolium sibiricum steppe, Stipa baicalensis steppe and Leymus chinense (syn. Aneurolepidium chinense) steppe relative to interannual variation of precipitation and temperature during 1981–1990 in the Tumugi, Xingan League, eastern Inner Mongolia of China. On the average, annual precipitation was 41.1 cm. Peak live aboveground biomass (PLAB) was 152 g m-2 for F. sibiricum steppe and S. baicalensis steppe and 162 g m-2 for L. chinense steppe. Peak live belowground biomass (PLBB) varied between 968 g m-2 for F. sibiricum steppe and 1022 g m-2 for L. chinense steppe. The coefficient of variation (CV) in annual precipitation (25%) was lower than the CV in PLAB (35% to 37%) but larger than the CV in PLBB (10%) of the three meadow steppe sites. Rain use efficiency was 3.6 gDM m-2 cm-1 yr-1 for F. sibiricum steppe and S. baicalensis steppe, and 3.9 gDM m-2 cm-1 yr-1 for L. chinense steppe, respectively.Using the CENTURY ecosystem model, simulation results agreed reasonably well with the observed soil organic matter, seasonal dynamics and interannual variation of plant biomass of these three steppe sites during 1981–1990. The CENTURY model is slightly more successful than the empirical regression models that use annual precipitation to estimate PLAB of these meadow steppe over time. Both seasonal distribution and interannal variation in precipitation and temperature are the important controls of temporal dynamics of plant biomass, rain use efficiency, carbon flux and storage of these meadow steppe ecosystems over time.  相似文献   

12.
草原区不同植物群落蒸发蒸腾的研究   总被引:35,自引:1,他引:34       下载免费PDF全文
 在中国科学院内蒙古草原生态系统定位研究站,采用“土柱称重法”对典型草原群落蒸发蒸腾进行实验观测,主要研究结果如下:1.草原沙地、羊草草原和河漫滩草甸是本地区差异明显的三种群落。草甸蒸腾最大(9.2 mm·d-1),比另两种群落高2—3倍;草甸蒸发最小(0.4mm·d-1),约为沙地的1/4,草原 的l/8。2.羊草草原在本区分布广,大针茅草原是本区半干旱地带性代表。由于这两种群落主要有关背景值的不同,羊草群落蒸散值(4.4—5.Omm·d-1)明显高于大针茅群落(3.5—3.8 mm·d-1),而且羊草群落的T/E1)值(~2)也明显大于大针茅(~1)。在生长季节中,羊草草原蒸散随气温升高而升高,在盛夏达最高值,然后随气温降低而降低。然而由于降雨变化的影响,羊草草原蒸发蒸腾的季节变化时而出现较大幅度的波动。3.根据1989年实测的降水和羊草群落蒸发蒸腾的季节变化,分析羊草群落的水分收支,可以看到实验区羊草草原的水分收支是大体平衡的。  相似文献   

13.
以内蒙古锡林河流域的两种优势草原群落羊草草原和大针茅草原为研究对象,探讨了中纬度地区未放牧情况下的草原生态系统植物营养元素的生物地球化学特征.结果表明,两类草原群落土壤-植物系统中土壤分室N、P、K、S、Ca、Mg、Si的贮量远大于植物亚系统的贮量,地上活体和枯草分室的各元素贮量小于根分室.在两类草原群落中,N、P、K、S从枯草分室中消失的速率要大于Ca、Mg和Si.羊草草原的枯草分室元素流失量大于大针茅草原.研究区草原生态系统中,羊革草原物质的生物地球化学循环近于平衡状态,大针茅草原处于失衡状态.物质循环量羊草草原远大于大针茅草原.  相似文献   

14.
中亚热带细柄阿丁枫和米槠群落细根的生产和死亡动态   总被引:1,自引:0,他引:1  
采用微根管技术与挖掘法相结合的方式对福建省万木林自然保护区细柄阿丁枫和米槠天然林细根生产和死亡动态进行了为期两年多的观测,分析细根生产和死亡的季节变化、垂直分布及径级和序级分配,并估计细根的年生产量和年死亡量.结果表明:细柄阿丁枫细根年生产量和年死亡量分别为(230.1±162.8) g·m-2·a-1和(188.8±75.5)g·m-2· a-1,均略大于米槠的(214.5±185.8) g·m-2·a-1和(178.8±26.5) g·m-2·a-1,但两种森林群落的细根年生产量和年死亡量均无显著差异(P>0.05).两森林群落细根生产均在春季达到高峰,其中米槠细根生产与月降水量呈极显著相关(P<0.01,r=0.566);细根死亡则呈现季节性地波动,米槠细根死亡峰值主要发生于夏季和秋季,而细柄阿丁枫则出现在秋季.两森林群落细根生产和死亡皆主要集中于土壤表层0-40 cm中,而且不同径级细根生产和死亡集中于0-1 mm细根中,其中0.3-0.6 mm细根的生产和死亡在两森林群落中均最大.两森林群落一级根的生产和死亡均大于高级根.  相似文献   

15.
The present paper deals mainly with the absorption, distribution and biological cycles of K, Ca and Mg in Rhizophora stylosa mangrove community in Yingluo Bay of Guangxi, China. The results showed that: In standing crop of the community, the total amounts of K, Ca and Mg were 46.26 g·m-2, 276. 33 g·m-2 and 50. 43 g·m-2, respectively. The Biological cycles of K, Ca and Mg in this stand were:annual uptake 4.46 g· m-2 for K, 17.46 g·m-2 for Ca and 4.81 g·m-2 for Mg ;annual retention 1.67 g·m-2 for K, 10.83 g·m-2 for Ca and 1.39 g·m-2 for Mg; annual return 2.79 g·m-2 for K, 6.63 g·m-2 for Ca an 3.42 g·m-2 for Mg. The enrichment ratios of K, Ca and Mg in this community were 1. 81, 1.20 and 1.80, respectively. The speed of turnover period (yr) was 17, 42 and 15, respectively,in which the speed of Mg recycling was the fastest.  相似文献   

16.
内蒙古典型草原地上净初级生产力对气候变化响应的模拟   总被引:2,自引:0,他引:2  
利用内蒙古锡林浩特国家气候观象台1994~2009年牧草生长季逐月实测资料,对CENTURY模型进行检验,模拟内蒙古典型草原1953~2010年间地上净初级生产力(ANPP)动态,并与26个气象因子进行相关性分析。模型检验结果显示,模拟值与观测值之间的相关系数为R2=0.66,斜率b=0.95,误差平方根值为50.51g.m-2,平均绝对百分比误差为44.19%。结果表明:(1)CENTURY模型能比较准确地模拟这类草原的季节动态和年际变化;在过去的58年中,内蒙古典型草原温度增加,降水减少,ANPP下降;ANPP变化趋势与降水量相似。(2)用实际气象观测资料模拟获得的ANPP随气温和降水的变化呈现出明显的变化规律,生长季内地上生物量对降水和温度的季节性分布也非常敏感;相关分析进一步表明,ANPP对生长季内降水量和极端高温非常敏感,而与年极端最低气温、平均地面温度、日照时数、平均风速和最大积雪深度无显著相关关系;过去58年研究区ANPP下降是降水减少、温度升高以及干旱事件频发共同作用的结果。(3)根据预测,在SRES B2情景下,未来50~100年内蒙古典型草原生长季平均最高气温和最低气温都将呈升高趋势,2080s分别升高4.01℃、4.35℃,每10年增加速率分别为0.35℃和0.38℃;降水量略呈增加,2020s、2050s和2080s研究区生长季将分别增加3.17%、5.13%和7.03%,每10年增加速率为0.09mm;ANPP呈下降趋势年际间波动较大,2020s、2050s和2080s研究区将分别下降5.76%、7.52%和11.42%,每10年下降速率为0.76g.m-2。  相似文献   

17.
At the site level, the authors used the Century plant-soil ecosystem model and Landsat remote sensing to estimate the aboveground biomass of Aneurolepidium chinense steppe and Stipa grandis steppe in the Xilin river basin, Inner Mongolia China. The results of century simulation matched well in terms of the seasonal and yearly change of biomass, with those of field moniforing. The results of field monitoring replicated well were about 142.45~144.37 g/m2 and 210. 38~227.44 g/m2 on S. grandis and A. chinense steppe, respectvely, whereas the simulation results were 127. 04~156. 23 g/m2 and 189.25~193.98 g/m2, respectively. Simulated soil organic matter was around ±–25% of the observed data. Normalized differnce vegetation index derived aboveground biomass was around ±25 % of the observed field biomass on the A. chinence and S. grandis steppe, using Landsat TM imagecries on July 31, 1987 and August 11, 1991. The effect of global climate change and elevated CO2 on these steppe was examined, using the climate fields from Global Change Models of Canadian Climate Center and Geophysics Flow Dynamics Laboratory under 1 × CO2 (350 X 10-6) and 2 × CO2 (700 X 10-6) sceneries. Climate change resulted in considerable decrease of primary productivity and soil organic matter of A. chinense and S. grandis steppe, the former being more sensitive to climate change.  相似文献   

18.
 采用碱液吸收法对锡林河流域温带典型草原一退化群落的土壤呼吸进行了测定,并分析了温度和水分对土壤呼吸的影响,结果表明:1)土壤呼吸总体趋势是夏季高,其它季节低,但季节动态呈现不规律的波动曲线;2)气温、地表温度以及5 cm、10 cm、15 cm和25 cm的土壤温度均与土壤呼吸速率呈显著的指数关系,温度对土壤呼吸的影响在低温时比高温时更显著;3)0~10 cm和10~20 cm土层的土壤含水量均与土壤呼吸速率呈显著的线性关系,消除气温的影响后则呈更为显著的乘幂关系;4)根据变量在p=0.05水平上的多元回归分析结果得到关于土壤呼吸与气温和10~20 cm土壤含水量的关系模型:y=5 911.648×e0.04216Ta×M20. 90758 (R2=0.8584,p<0.0001) ,这一模型比单变量模型能更好地解释土壤呼吸的变化情况;5)实验期间土壤呼吸的平均速率为661.35 mgC·m-2·d-1,以气温、地表温度以及5 cm、10 cm、15 cm和25 cm的土壤温度为依据得到的Q10值依次为1.63、1.47、1.52、1.70、1.90、1.97。  相似文献   

19.
模拟氮沉降对华西雨屏区光皮桦林土壤酶活性的影响   总被引:6,自引:0,他引:6  
在华西雨屏区光皮桦(Betula luminifera)人工林内设置不同氮沉降水平(0、5、15和30 g N·m-2·a-1)的模拟氮沉降试验,研究氮沉降对林地土壤酶活性的影响.结果表明:模拟氮沉降促进了光皮桦人工林土壤中水解酶(蔗糖酶、纤维素酶、酸性磷酸酶和脲酶)活性,抑制了氧化酶(多酚氧化酶和过氧化物酶)活性.土壤水解酶活性的增强预示着在活性氮增加的情况下,光皮桦和土壤微生物对碳、磷元素的需求增加.外源无机氮的增加显著降低了土壤多酚氧化酶和过氧化物酶的活性,可能导致凋落物分解受到抑制,促进凋落物在土壤中的积累,并通过抑制土壤有机质的分解增加土壤中碳的贮存量.  相似文献   

20.
深入认识植物功能性状的生态学含义, 对于阐明不同自然与人为干扰环境下的群落构建途径, 进一步揭示生态系统服务维持机制具有重要的理论意义。该文以内蒙古锡林河流域羊草(Leymus chinensis)草原不同退化演替阶段的群落为研究对象, 分析了土壤养分与植物功能性状的变化特征及两者之间的关系。结果表明: (1)退化导致土壤养分含量逐渐减少, 全氮和全磷在未退化的羊草+杂类草群落与严重退化的羊草+冷蒿(Artemisia frigida)群落之间差异显著; (2)随着退化演替的进程, 群落最大高度和叶片碳氮比减小, 群落最大高度在未退化的羊草+杂类草群落与轻度退化的羊草+针茅(Stipa sp.)群落之间差异显著, 碳氮比在未退化的羊草+杂类草群落与严重退化的羊草+冷蒿群落之间差异显著; (3)不同退化演替阶段的群落, 其土壤养分对植物功能性状的影响有所差异。在羊草+针茅群落, 速效氮与群落最大高度、叶片木质素含量和叶片碳氮比均呈显著负相关关系。而在羊草+糙隐子草(Cleistogenes squarrosa)群落中, 上述3种植物功能性状则表现为均与全磷含量显著正相关; (4)群落植物功能性状之间的关系也因退化阶段不同而有所不同。在轻度退化的羊草+针茅群落中, 叶片木质素含量与其他4个功能性状显著正相关, 叶片碳氮比与群落最大高度、叶干物质含量、木质素含量呈显著正相关关系。在严重退化的羊草+冷蒿群落中, 所有性状均呈极显著正相关关系。表明植物通过功能性状的协调或组合, 以适应贫瘠的土壤环境。上述结果深化了对典型草原退化演替的认识, 对退化草地的恢复与保护具有一定的指导意义。  相似文献   

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