全文获取类型
收费全文 | 9675篇 |
免费 | 1117篇 |
国内免费 | 3172篇 |
专业分类
安全科学 | 1158篇 |
废物处理 | 368篇 |
环保管理 | 763篇 |
综合类 | 6790篇 |
基础理论 | 1532篇 |
环境理论 | 1篇 |
污染及防治 | 1586篇 |
评价与监测 | 565篇 |
社会与环境 | 823篇 |
灾害及防治 | 378篇 |
出版年
2024年 | 73篇 |
2023年 | 236篇 |
2022年 | 640篇 |
2021年 | 682篇 |
2020年 | 726篇 |
2019年 | 510篇 |
2018年 | 489篇 |
2017年 | 566篇 |
2016年 | 523篇 |
2015年 | 603篇 |
2014年 | 693篇 |
2013年 | 849篇 |
2012年 | 873篇 |
2011年 | 836篇 |
2010年 | 698篇 |
2009年 | 723篇 |
2008年 | 674篇 |
2007年 | 584篇 |
2006年 | 567篇 |
2005年 | 430篇 |
2004年 | 302篇 |
2003年 | 286篇 |
2002年 | 269篇 |
2001年 | 214篇 |
2000年 | 226篇 |
1999年 | 134篇 |
1998年 | 113篇 |
1997年 | 82篇 |
1996年 | 72篇 |
1995年 | 49篇 |
1994年 | 51篇 |
1993年 | 46篇 |
1992年 | 39篇 |
1991年 | 20篇 |
1990年 | 18篇 |
1989年 | 12篇 |
1988年 | 13篇 |
1986年 | 8篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 8篇 |
1981年 | 2篇 |
1978年 | 6篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
941.
城乡交错带土地利用方式对土壤理化性质的影响 总被引:2,自引:0,他引:2
以长沙市南郊山地丘陵区为研究对象,选择7种不同土地利用方式(次生林地、经济林地、杉木人工林、采伐迹地、撂荒地、苗圃地、坡耕地)研究了城乡交错带不同土地利用方式对土壤理化性质的影响。结果表明:7种土地利用方式下,土壤颗粒组成主要集中在1~0.05 mm和<0.001 mm两个粒级范围内,土壤质地以重壤土和轻粘土为主。随着人为干扰程度的减弱,土壤砂粒(1.0~0.05 mm)、土壤粉粒(0.05~0.01 mm)百分率逐渐下降,<0.01 mm的土壤物理性粘粒百分率增加。自然、半自然状态利用方式的林地(次生林地、经济林地、杉木人工林地)土壤总孔隙度、含水量普遍较高,土壤密度低于坡耕地、苗圃地、撂荒地、采伐迹地,而土壤pH值、有机质含量及氮、磷、钾含量普遍高于坡耕地、苗圃地、撂荒地、采伐迹地 相似文献
942.
The dissipation of carbendazim and chloramphenicol alone and in combination and their effects on soil fungal:bacterial ratios and soil enzyme activities were investigated. The results revealed that carbendazim dissipation was little affected by chloramphenicol, whereas chloramphenicol dissipation was found to be retarded significantly by the presence of carbendazim. The inhibitory effect of carbendazim on the fungal:bacterial ratios was increased by the presence of chloramphenicol, and the inhibitory effect of chloramphenicol on neutral phosphatase was increased by the presence of carbendazim. Carbendazim increased soil catalase and urease activities, but this increase was partially diminished by the presence of chloramphenicol. Little interaction was observed between carbendazim and chloramphenicol with regard to their influence on soil invertase. The results obtained in this study suggest that combinations of fungicides and antibiotics may alter the compounds’ individual behaviors in soil and their effects on soil enzymes. 相似文献
943.
The sorption of Cu(II) from an aqueous solution using ZSM-5 zeolite was investigated by batch technique under ambient conditions. Sorption was investigated as a function of pH, ionic strength, foreign ions, humic substances, and temperature. The results indicate that the sorption of Cu(II) on ZSM-5 zeolite is strongly dependent on pH. Sorption is dependent on ionic strength at low pH, but independent of ionic strength at high pH values. The presence of humic/fluvic acid (HA/FA) enhances the sorption of Cu(II) on ZSM-5 zeolite at low pH values, and reduces Cu(II) sorption at high pH values. Sorption isotherms were well simulated by the Langmuir model. Thermodynamic parameters (i.e., deltaH0, deltaS0 and deltaG0) for the sorption of Cu(II) were determined from temperature-dependent sorption isotherms at 293.15, 313.15, and 333.15 K, respectively. Results indicate that the sorption process of Cu(II) on ZSM-5 zeolite is spontaneous and endothermic. 相似文献
944.
A livestock odor dispersion model (LODM) was developed to predict mean odor concentration, odor frequency, instantaneous odor concentration, and peak odor concentration from livestock operations. This model is based on the Gaussian fluctuating plume model and has the ability to consider the instantaneous concentration fluctuations and the differences between odor and traditional air pollutants. It can predict odor frequency from the routine hourly meteorological data input and deal with different types of sources and multiple sources. Also, the relationship between odor intensity and odor concentration was incorporated into the model. 相似文献
945.
946.
947.
948.
949.
950.