全文获取类型
收费全文 | 11458篇 |
免费 | 921篇 |
国内免费 | 3476篇 |
专业分类
安全科学 | 763篇 |
废物处理 | 512篇 |
环保管理 | 1735篇 |
综合类 | 7219篇 |
基础理论 | 2968篇 |
环境理论 | 8篇 |
污染及防治 | 1388篇 |
评价与监测 | 492篇 |
社会与环境 | 526篇 |
灾害及防治 | 244篇 |
出版年
2024年 | 16篇 |
2023年 | 104篇 |
2022年 | 187篇 |
2021年 | 224篇 |
2020年 | 239篇 |
2019年 | 256篇 |
2018年 | 211篇 |
2017年 | 303篇 |
2016年 | 316篇 |
2015年 | 356篇 |
2014年 | 434篇 |
2013年 | 928篇 |
2012年 | 843篇 |
2011年 | 668篇 |
2010年 | 508篇 |
2009年 | 604篇 |
2008年 | 447篇 |
2007年 | 754篇 |
2006年 | 743篇 |
2005年 | 573篇 |
2004年 | 475篇 |
2003年 | 481篇 |
2002年 | 517篇 |
2001年 | 471篇 |
2000年 | 606篇 |
1999年 | 640篇 |
1998年 | 519篇 |
1997年 | 498篇 |
1996年 | 555篇 |
1995年 | 468篇 |
1994年 | 390篇 |
1993年 | 286篇 |
1992年 | 214篇 |
1991年 | 234篇 |
1990年 | 142篇 |
1989年 | 111篇 |
1988年 | 73篇 |
1987年 | 72篇 |
1986年 | 42篇 |
1985年 | 38篇 |
1984年 | 80篇 |
1983年 | 57篇 |
1982年 | 30篇 |
1981年 | 13篇 |
1980年 | 13篇 |
1979年 | 11篇 |
1977年 | 8篇 |
1976年 | 28篇 |
1975年 | 34篇 |
1974年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
文教区土壤环境质量直接影响学生以及职工的身体健康。本研究应用高效液相色谱仪对采集的西安市文教区表层土壤样品中的16种优控多环芳烃(PAHs)进行含量检测,分析其组分特征、来源及健康风险。结果表明,西安市文教区表层土壤中∑PAHs含量为0.290~4.147μg/g,平均值为1.515μg/g,7种致癌多环芳烃的含量为0.079~2.093μg/g,均值为0.593μg/g,土壤PAHs污染较为严重。其中4环的高环PAHs为土壤PAHs污染的主要物质,平均占∑PAHs含量的40.72%。源解析结果表明西安市文教区表层土壤中PAHs主要来源于石油燃烧、煤及生物质等的不完全燃烧。终生癌症风险评价表明西安市文教区表层土壤中PAHs污染对其生活在周围的人群产生的终生致癌风险性较小,但71.4%的样点达到严重污染水平,产生的间接影响应引起足够重视。 相似文献
42.
The research, focused on the specific interactions among seven plant secondary compounds and aphids, was carried out and the preliminary results showed: (1) "T-typed tube method" was regarded as the best method compared with others designed to observe the interactions. (2) Cabbage aphid was able to be attracted by laurolene while it was not susceptible to α-pinene, β-pinene and diamylene. (3) Gossypol, a major secondary substance in cotton, was able to be implicated as feeding attractant to cotton aphid. (4) Rutin might be implicated repellent to cotton aphid. 相似文献
43.
44.
Several theoretical, analytical, and institutional difficulties have impeded the development and application of the assessment of cumulative environmental impacts. Watershed development on coastal wetlands offers an ideal context for evaluating the land disturbance target approach to cumulative impact assessment. A model land use planning system involving a time series approach was developed for Elkhorn Slough in California. The approach included four major components: evaluation of erosion susceptibility, measurement of land disturbance, establishment of a land disturbance target, and a comparison of existing and target land disturbance values. Further research is needed to test the transferability of the approach in a wide range of coastal watersheds and to verify the applicability of the methods to other cumulative impact problems. 相似文献
45.
青铜峡铝厂氟污染对广武乡玉米影响的调查分析 总被引:1,自引:0,他引:1
监测了青铜峡铝厂东南方向4.5km的广武乡玉米叶,得知含氟量为43.94-166.1mg/kg,对照样品树新林场玉米叶的含氟均值为13.15mg/kg,广武乡的玉米受到了严重的氟污染,农作物减产严重。 相似文献
46.
47.
Although the process of documenting compliance with NEPA (the National Environmental Policy Act) requires no drastic revisions, it can be managed more rigorously. Suggestions for revision can be grouped under five major steps: 1) getting a complete proposal from the applicant; 2) getting the decision-making process onto the right decision-making path; 3) modifying the applicant's proposal 4) going down a shorter path through the EA/FONSI (environmental assessment and finding of no significant impact) or through categorical exclusion review; and 5) going down the longer path through the EIS. Step 2 is perhaps the most critical, because there a decision must be made whether to write an EA/FONSI or an EIS, on the basis of whether the proposal would “significantly affect … the … environment.” In the past, this decision has not always been made promptly or rigorously. Accordingly, we suggest that the agency responsible for NEPA compliance should develop a system (a “black box”), consisting of a core group of specialists working with an interdisciplinary team, using sophisticated techniques for modeling impacts and directing both their research and their writing according to the concept of significance. By determining more efficiently and reliably whether the impacts of a proposal would be significant, such an approach would improve management of the total process. 相似文献
48.
本文介绍一种灵敏而准确的高效液相色谱测定花粉素中五种水溶性维生素(即B_1、B_2、B_5、B_6和B_(12))方法。研究了移动相醋酸盐缓冲溶液的浓度和PH对色谱分离效果的影响,水溶性维生素的定量分析是用日立3011-N的填充柱(其内径为4毫米,长250毫米),以含有2.5%乙醇的醋酸钠-醋酸组成的缓冲溶液(PH6)作为移动相,在波长254纳米处进行紫外检测,变异系数和回收率分别为2-5%和91.0-101.5%。 相似文献
50.
Virendra Misra Shri Dhar Pandey P. N. Viswanathan 《Environmental monitoring and assessment》2000,61(2):231-237
Effect of various concentrations of humic acid (0.2 to 1%) on thebioavailability of -HCH in vegetative clones of theaquatic fern Marsilea minuta was studied in a staticexperimental bioassay system on different photoperiods. Additionof humic acid showed the reduction in the bioavailability of-HCH in all the photoperiods (72 hr light to 144 hrlight) at the interval of 16 hr light (L) and 8 hr dark (D) inboth aerial and submerged portion as compared to controlindicating its protective role in toxicity. 相似文献