全文获取类型
收费全文 | 2188篇 |
免费 | 106篇 |
国内免费 | 307篇 |
专业分类
安全科学 | 694篇 |
废物处理 | 37篇 |
环保管理 | 212篇 |
综合类 | 1076篇 |
基础理论 | 175篇 |
污染及防治 | 208篇 |
评价与监测 | 57篇 |
社会与环境 | 65篇 |
灾害及防治 | 77篇 |
出版年
2024年 | 9篇 |
2023年 | 33篇 |
2022年 | 38篇 |
2021年 | 51篇 |
2020年 | 46篇 |
2019年 | 34篇 |
2018年 | 30篇 |
2017年 | 69篇 |
2016年 | 62篇 |
2015年 | 78篇 |
2014年 | 172篇 |
2013年 | 130篇 |
2012年 | 114篇 |
2011年 | 153篇 |
2010年 | 125篇 |
2009年 | 126篇 |
2008年 | 187篇 |
2007年 | 227篇 |
2006年 | 168篇 |
2005年 | 189篇 |
2004年 | 113篇 |
2003年 | 67篇 |
2002年 | 70篇 |
2001年 | 59篇 |
2000年 | 45篇 |
1999年 | 45篇 |
1998年 | 21篇 |
1997年 | 24篇 |
1996年 | 24篇 |
1995年 | 18篇 |
1994年 | 17篇 |
1993年 | 10篇 |
1992年 | 10篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 10篇 |
1987年 | 1篇 |
1986年 | 4篇 |
排序方式: 共有2601条查询结果,搜索用时 8 毫秒
331.
永海会地区的区域构造、含矿地层和建造、中生代火山侵入岩体特征、局部控矿构造以及成矿物质来源、硫氢氧同位素、铅同位素、年龄同位素等成矿信息,都与扬子区、萍乐区已知铜金矿集区有许多相似之处。通过对比表明,永海会地区具有极大的找矿前应景。 相似文献
332.
333.
334.
基于不同利益相关方认知的水源地生态补偿探讨——以上海市水源地和用水区居民问卷调查为例 总被引:4,自引:1,他引:4
采用实地问卷调查和条件价值法评估上海市饮用水源保护的利益相关方认知,探讨黄浦江上游水源地生态补偿机制。研究结果表明,当前水源保护相关政策认知比例普遍较低,水源地部分居民福利受到一定影响,对政府补偿政策的期望较为一致,用水区多数居民愿意分担部分水源保护的责任和义务;水源地WTA和用水区WTP分别为1526元/(月•户)和306元/(月•户),相应未来5年的总受偿意愿和总支付意愿为759.48×108元和465.08×108元;生态补偿方案的合理设计以及不同利益相关方的良好沟通是解决水源地环境冲突的关键。 相似文献
335.
旅游业是社会经济的重要组成部分,但其发展过程中出现了严重的资源破坏、环境污染问题,甚至影响到它进一步发展。绿色景区创建是改变旅游业粗放经营现状、解决旅游环境问题、构建和谐社会的需要。本文阐述了绿色景区的基本内涵与创建意义,指出绿色景区创建的基本任务、方法程序和核心内容以及绿色景区创建的支撑条件与技术保障措施,为绿色景区创建提供基本思路,对旅游业持续发展具有积极意义。 相似文献
336.
SAIDI Neyla KOUKI Soulwene M' HIRI Fadhel JEDIDI Naceur MAHROUK Meriam HASSEN Abdennaceur OUZARI Hadda 《环境科学学报(英文版)》2009,21(10):1452-1458
The aim of this study was to characterize the biological stability and maturity degree of compost during a controlled pile-composting trial of mixed vegetable residues (VR) collected from markets of Tunis City with residues of Posidonia oceanica (PoR), collected from Tunis beaches. The accumulation in beaches (as well as their removal) constitutes a serious environmental problem in all Mediterranean countries particularly in Tunisia. Aerobic-thermophilic composting is the most reasonable way to profit highly-valuable content of organic matter in these wastes for agricultural purposes. The physical, chemical, and biological parameters were monitored during composting over 150 d. The most appropriate parameters were selected to establish the maturity degree. The main result of this research was the deduction of the following maturity criterion: (a) C/N ratio < 15; (b) NH4+-N < 400 mg/kg; (c) CO2-C < 2000 mg CO2-C/kg; (d) dehydrogenase activity < 1 mg TPF/g dry matter; (e) germination index (GI) > 80%. These five parameters, considered jointly are indicative of a high maturity degree and thus of a high-quality organic amendment which employed in a rational way, may improve soil fertility and soil quality. The mature compost was relatively rich in N (13.0 g/kg), P (4.74 g/kg) and MgO (15.80 g/kg). Thus composting definitively constitutes the most optimal option to exploit these wastes. 相似文献
337.
338.
339.
340.
Orthophosphate is an essential but limiting macronutrient for plant growth. About 67% cropland in China lacks sufficient phosphorus, especially that with red soil. Extensive soil phosphorus reserves exist in the form of organic phosphorus, which is unavailable for root uptake unless hydrolyzed by secretory acid phosphatases. Thus, many microorganisms with the ability to produce phosphatase have been exploited. In this work, the activity of an extracellular acid phosphatase and yeast biomass from Candida mycoderma was measured under different culture conditions, such as pH, temperature, and carbon source. A maximal phosphatase activity of 8.47 × 10^5±0.11× 10^5 U/g was achieved by C. Mycoderma in 36 hr under the optimal conditions. The extracellular acid phosphatase has high activity over a wide pH tolerance range from 2.5 to S.0 (optimum pH 3.5). The effects of different phosphorus compounds on the acid phosphatase production were also studied. The presence of phytin, lecithin or calcium phosphate reduced the phosphatase activity and biomass yield significantly. In addition, the pH of the culture medium was reduced significantly by lecithin. The efficiency of the strain in releasing orthophosphate from organic phosphorus was studied in red soil (used in planting trees) and rice soil (originating as red soil). The available phosphorus content was increased by 230% after inoculating 20 days in rice soil and decreased by 50% after inoculating 10 days in red soil. This work indicates that the yeast strain C. mycoderma has potential application for enhancing phosphorus utilization in plants that grow in rice soil. 相似文献