全文获取类型
收费全文 | 5850篇 |
免费 | 516篇 |
国内免费 | 625篇 |
专业分类
安全科学 | 1219篇 |
废物处理 | 153篇 |
环保管理 | 1095篇 |
综合类 | 2983篇 |
基础理论 | 413篇 |
污染及防治 | 337篇 |
评价与监测 | 408篇 |
社会与环境 | 164篇 |
灾害及防治 | 219篇 |
出版年
2024年 | 20篇 |
2023年 | 65篇 |
2022年 | 108篇 |
2021年 | 174篇 |
2020年 | 227篇 |
2019年 | 150篇 |
2018年 | 108篇 |
2017年 | 208篇 |
2016年 | 199篇 |
2015年 | 241篇 |
2014年 | 256篇 |
2013年 | 307篇 |
2012年 | 401篇 |
2011年 | 482篇 |
2010年 | 333篇 |
2009年 | 300篇 |
2008年 | 211篇 |
2007年 | 349篇 |
2006年 | 409篇 |
2005年 | 282篇 |
2004年 | 271篇 |
2003年 | 274篇 |
2002年 | 241篇 |
2001年 | 203篇 |
2000年 | 190篇 |
1999年 | 175篇 |
1998年 | 136篇 |
1997年 | 103篇 |
1996年 | 95篇 |
1995年 | 86篇 |
1994年 | 64篇 |
1993年 | 69篇 |
1992年 | 47篇 |
1991年 | 24篇 |
1990年 | 20篇 |
1989年 | 9篇 |
1987年 | 12篇 |
1986年 | 13篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 17篇 |
1979年 | 10篇 |
1978年 | 10篇 |
1977年 | 7篇 |
1973年 | 5篇 |
1972年 | 5篇 |
1971年 | 9篇 |
排序方式: 共有6991条查询结果,搜索用时 370 毫秒
521.
522.
介绍了湖北省清江高坝洲津洋口防护区的概况,对津洋口防护区水环境污染现状进行了分析和调查研究,同时得出了防护区的主要污染为工业废水污染.计算了津洋口防护区丹水河的水环境容量,并据此提出水环境污染治理方案. 相似文献
523.
铁路建设项目的生态环境影响在其全生命周期内各时期有不同的表现形式.在阐述不同时期应重点关注的生态环境保护问题的基础上,从全过程控制角度,建立了涵盖前期规划、建设期、运营期3个阶段的铁路建设项目生态环境保护发展状况评估指标体系,运用层次分析法对各指标进行权重评定.根据权重计算结果对铁路建设项目生态环境保护工作中重要时期及... 相似文献
524.
HEIKO U. WITTMER ROBERT SERROUYA L. MARK ELBROCH ANDREW J. MARSHALL 《Conservation biology》2013,27(2):254-260
Apparent competition is an indirect interaction between 2 or more prey species through a shared predator, and it is increasingly recognized as a mechanism of the decline and extinction of many species. Through case studies, we evaluated the effectiveness of 4 management strategies for species affected by apparent competition: predator control, reduction in the abundances of alternate prey, simultaneous control of predators and alternate prey, and no active management of predators or alternate prey. Solely reducing predator abundances rapidly increased abundances of alternate and rare prey, but observed increases are likely short‐lived due to fast increases in predator abundance following the cessation of control efforts. Substantial reductions of an abundant alternate prey resulted in increased predation on endangered huemul (Hippocamelus bisulcus) deer in Chilean Patagonia, which highlights potential risks associated with solely reducing alternate prey species. Simultaneous removal of predators and alternate prey increased survival of island foxes (Urocyon littoralis) in California (U.S.A.) above a threshold required for population recovery. In the absence of active management, populations of rare woodland caribou (Rangifer tarandus caribou) continued to decline in British Columbia, Canada. On the basis of the cases we examined, we suggest the simultaneous control of predators and alternate prey is the management strategy most likely to increase abundances and probabilities of persistence of rare prey over the long term. Knowing the mechanisms driving changes in species’ abundances before implementing any management intervention is critical. We suggest scientists can best contribute to the conservation of species affected by apparent competition by clearly communicating the biological and demographic forces at play to policy makers responsible for the implementation of proposed management actions. Estrategias de Conservación para Especies Afectadas por Competencia Aparente 相似文献
525.
在钢铁企业有效应用安全评价,不但能够有效识别现场的危险因素,确定危险源,及时妥善地采取安全对策措施,还能够促进安全管理重心下移,实现逐级管理,更有利于消除现场人的不安全行为和物的不安全状态. 相似文献
526.
Miguel Gimeno 《Journal of environmental science and health. Part. B》2013,48(3):407-420
Abstract For the production of controlled‐release agricultural formulations microencapsulation technologies are now the most used. Over the past two decades enormous progress has been made in order to develop the technologies which allow us to produce formulations tailor made to reach the target and fitting our toxicological requirements. This lecture is devoted to the definition of the criteria for selection of an active ingredient for microencapsulation and to a detailed review of the various techniques used today in commerçai microencapsulated formulations. Resources are increasingly allocated into microencapsulation research & development by many agrochemical companies. Therefore the next 20 years should continue to yield innovative ideas including significant improvement of the physico‐chemical and toxicological properties of the actual formulations on the market. Some of this new ideas are applied by our company in order to modify or improve those properties playing the key role in the intent for targeted activity: √ Recombination during production or upon storage. New protective colloides Dermal toxicity (LD 50) ‐ secondary protective colloides. √ Release rate parameters. Modification by the change of mobility of the active ingredient from the core (solvent or fluid type) affecting transit time and therefore LD 50 values. √ Oral toxicity (LD 50). Graft copolymers irreversibly adsorbed to the capsule surface. 相似文献
527.
Rui Xu Peter E. Mortimer Rong Ping Kuang Jun He Wu Di Zhang Fang Yin 《Journal of environmental science and health. Part. B》2013,48(8):651-657
This study focuses on assessing the impact of sublethal doses of paraquat on the survival, the emergence, the life span and the parasitic behavior of Diaeretiella rapae M’Intosh (Hymenoptera: Braconidae). The impact of sublethal doses was measured at room temperature using different densities of the cabbage aphid Brevicoryne brassicae. The results reveal that the field dose of paraquat caused 100% mortality in D. rapae. The percentage emergence of D. rapae decreased from 80.5% in the control group to 71.5% when treated with the lowest concentration of paraquat. Similarly, the life span of parasitoids that emerged from the mummy treated with paraquat also decreased significantly. Oviposition capability and ovipositor thrusting frequency of D. rapae also treated with sublethal dose paraquat decreased significantly along with a shortened patch residence time in the foraging area. 相似文献
528.
本文综合论述了在水业市场化条件下,水务投资公司进行污水处理厂投资、建设和运营时,在投资决策前期阶段、设计阶段、建设阶段以及运营阶段等各水务价值链重要环节的成本控制方法,为水务投资公司在污水厂投资全过程的成本控制提供了参考。 相似文献
529.
Citizen science networks in natural history and the collective validation of biodiversity data 下载免费PDF全文
Biodiversity data are in increasing demand to inform policy and management. A substantial portion of these data is generated in citizen science networks. To ensure the quality of biodiversity data, standards and criteria for validation have been put in place. We used interviews and document analysis from the United Kingdom and The Netherlands to examine how data validation serves as a point of connection between the diverse people and practices in natural history citizen science networks. We found that rather than a unidirectional imposition of standards, validation was performed collectively. Specifically, it was enacted in ongoing circulations of biodiversity records between recorders and validators as they jointly negotiated the biodiversity that was observed and the validity of the records. These collective validation practices contributed to the citizen science character or natural history networks and tied these networks together. However, when biodiversity records were included in biodiversity‐information initiatives on different policy levels and scales, the circulation of records diminished. These initiatives took on a more extractive mode of data use. Validation ceased to be collective with important consequences for the natural history networks involved and citizen science more generally. 相似文献
530.
环境保护同经济建设和社会发展相协调,是我国环境保护的基本原则。本文从环境保护与经济发展的相互关系出发,比较实际地估计了我省各种污染排放物及造成的经济损失,探讨了环保治理资金社会投入的比例问题。 相似文献