全文获取类型
收费全文 | 2319篇 |
免费 | 325篇 |
国内免费 | 202篇 |
专业分类
安全科学 | 66篇 |
废物处理 | 40篇 |
环保管理 | 550篇 |
综合类 | 685篇 |
基础理论 | 1165篇 |
环境理论 | 3篇 |
污染及防治 | 119篇 |
评价与监测 | 65篇 |
社会与环境 | 144篇 |
灾害及防治 | 9篇 |
出版年
2024年 | 5篇 |
2023年 | 80篇 |
2022年 | 64篇 |
2021年 | 99篇 |
2020年 | 99篇 |
2019年 | 108篇 |
2018年 | 91篇 |
2017年 | 105篇 |
2016年 | 102篇 |
2015年 | 133篇 |
2014年 | 114篇 |
2013年 | 160篇 |
2012年 | 120篇 |
2011年 | 142篇 |
2010年 | 152篇 |
2009年 | 157篇 |
2008年 | 131篇 |
2007年 | 161篇 |
2006年 | 114篇 |
2005年 | 92篇 |
2004年 | 91篇 |
2003年 | 49篇 |
2002年 | 54篇 |
2001年 | 54篇 |
2000年 | 42篇 |
1999年 | 38篇 |
1998年 | 39篇 |
1997年 | 29篇 |
1996年 | 24篇 |
1995年 | 25篇 |
1994年 | 24篇 |
1993年 | 21篇 |
1992年 | 13篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 12篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 10篇 |
1980年 | 10篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1975年 | 3篇 |
1972年 | 3篇 |
1971年 | 4篇 |
排序方式: 共有2846条查询结果,搜索用时 312 毫秒
11.
12.
以闽江河口塔礁洲感潮淡水野慈姑(Sagittaria trifolia Linn.)湿地为研究对象,于2016年2、4、7和9月每月均在连续2个小潮日内向研究样地施加人造海水和Fe(OH)_3溶液,研究短期的盐水入侵及Fe(III)浓度增强对河口感潮淡水湿地土壤反硝化速率及理化特征的影响.结果表明,短期的盐水入侵、Fe(III)浓度增强对河口感潮淡水沼泽湿地土壤反硝化速率的影响不显著,然而,盐水和Fe(III)共同施加会显著提高湿地土壤反硝化速率,与对照(CK)相比,盐水和Fe(III)共同施加可使土壤反硝化速率提高270.9%.盐水入侵、盐水和Fe(III)共同施加均可显著提高湿地土壤、间隙水的电导率及Cl~-、SO_4~(2-)的含量;Fe(III)浓度增强可显著降低土壤和间隙水pH值,同时显著提高土壤三价铁含量. 相似文献
13.
石墨炉原子吸收光谱法测定海河下游水中痕量镉 总被引:2,自引:0,他引:2
原子吸收光谱法直接测定高盐水中痕量镉时,有很大背景吸收和误差。本文采用络合—萃取技术使共存元素与待测元素分离,既消除了基体干扰,又达到了富集作用,使测定结果准确可靠。 相似文献
14.
Rice WE 《Environmental monitoring and assessment》2004,99(1-3):251-257
A sub-surface desert water harvester was constructed in the sagebrush steppe habitat of south-central Idaho, U.S.A. The desert
water harvester utilizes a buried micro-catchment and three buried storage tanks to augment water for wildlife during the
dry season. In this region, mean annual precipitation (MAP) ranges between about 150–250 mm (6″–10″), 70% of which falls during
the cold season, November to May. Mid-summer through early autumn, June through October, is the dry portion of the year. During
this period, the sub-surface water harvester provides supplemental water for wildlife for 30–90 days, depending upon the precipitation
that year. The desert water harvester is constructed with commonly available, “over the counter” materials. The micro-catchment
is made of a square-shaped, 20 mL. “PERMALON” polyethylene pond liner (approximately 22.9 m × 22.9 m = 523 m2) buried at a depth of about 60 cm. A PVC pipe connects the harvester with two storage tanks and a drinking trough. The total
capacity of the water harvester is about 4777 L (1262 U.S. gallons) which includes three underground storage tanks, a trough
and pipes. The drinking trough is refined with an access ramp for birds and small animals. The technology is simple, cheap,
and durable and can be adapted to other uses, e.g. drip irrigation, short-term water for small livestock, poultry farming
etc. The desert water harvester can be used to concentrate and collect water from precipitation and run-off in semi-arid and
arid regions. Water harvested in such a relatively small area will not impact the ground water table but it should help to
grow small areas of crops or vegetables to aid villagers in self-sufficiency. 相似文献
15.
Conservation and management applications of the REEF volunteer fish monitoring program 总被引:2,自引:0,他引:2
Pattengill-Semmens CV Semmens BX;Reef Environmental Education Foundation 《Environmental monitoring and assessment》2003,81(1-3):43-50
The REEF Fish Survey Project is a volunteer fish monitoring program developed by the Reef Environmental Education Foundation (REEF). REEF volunteers collect fish distribution and abundance data using a standardized visual method during regular diving and snorkeling activities. Survey data are recorded on preprinted data sheets that are returned to REEF and optically digitized. Data are housed in a publicly accessible database on REEF's Web site (http: //www.reef.org). Since the project's inception in 1993, over 40,000 surveys have been conducted in the coastal waters of North America, tropical western Atlantic, Gulf of California and Hawaii. The Fish Survey Project has been incorporated into existing monitoring programs through partnerships with government agencies, scientists, conservation organizations, and private institutions. REEF's partners benefit from the educational value and increased stewardship resulting from volunteer data collection. Applications of the data include an evaluation of fish/habitat interactions in the Florida Keys National Marine Sanctuary, the development of a multi-species trend analysis method to identify sites of management concern, assessment of the current distribution of species, status reports on fish assemblages of marine parks, and the evaluation of no-take zones in the Florida Keys. REEF's collaboration with a variety of partners, combined with the Fish Survey Project's standardized census method and database management system, has resulted in a successful citizen science monitoring program. 相似文献
16.
Darek J. Nalle Jeffrey L. Arthur Claire A. Montgomery John Sessions 《Environmental Modeling and Assessment》2002,7(2):99-105
An optimization model for land reservation was developed that explicitly selects parcels in the most compact or contiguous manner possible while meeting habitat requirements and a budget limitation. The model was used to compare the effects of an existing reserve network on future parcel spatial locations and total cost. Using habitat and land value data from Josephine County, Oregon, it was found that a system of existing reserves created by various policies and overseen by different agencies can decrease future reserve compactness and contiguity, and increase total cost. This work suggests that coordinated planning can result in more efficient conservation efforts for less cost. 相似文献
17.
William F. Laurance 《Environmental monitoring and assessment》2000,61(1):113-122
This paper describes four global-change phenomena that are having major impacts on Amazonian forests. The first is accelerating deforestation and logging. Despite recent government initiatives to slow forest loss, deforestation rates in Brazilian Amazonia have increased from 1.1 million ha yr–1 in the early 1990s, to nearly 1.5 million ha yr–1 from 1992–1994, and to more than 1.9 million ha yr–1 from 1995–1998. Deforestation is also occurring rapidly in some other parts of the Amazon Basin, such as in Bolivia and Ecuador, while industrialized logging is increasing dramatically in the Guianas and central Amazonia.The second phenomenon is that patterns of forest loss and fragmentation are rapidly changing. In recent decades, large-scale deforestation has mainly occurred in the southern and eastern portions of the Amazon — in the Brazilian states of Pará, Maranho, Rondônia, Acre, and Mato Grosso, and in northern Bolivia. While rates of forest loss remain very high in these areas, the development of major new highways is providing direct conduits into the heart of the Amazon. If future trends follow past patterns, land-hungry settlers and loggers may largely bisect the forests of the Amazon Basin.The third phenomenon is that climatic variability is interacting with human land uses, creating additional impacts on forest ecosystems. The 1997/98 El Niño drought, for example, led to a major increase in forest burning, with wildfires raging out of control in the northern Amazonian state of Roraima and other locations. Logging operations, which create labyrinths of roads and tracks in forsts, are increasing fuel loads, desiccation and ignition sources in forest interiors. Forest fragmentation also increases fire susceptibility by creating dry, fire-prone forest edges.Finally, recent evidence suggests that intact Amazonian forests are a globally significant carbon sink, quite possibly caused by higher forest growth rates in response to increasing atmospheric CO2 fertilization. Evidence for a carbon sink comes from long-term forest mensuration plots, from whole-forest studies of carbon flux and from investigations of atmospheric CO2 and oxygen isotopes. Unfortunately, intact Amazonian forests are rapidly diminishing. Hence, not only is the destruction of these forests a major source of greenhouse gases, but it is reducing their intrinsic capacity to help buffer the rapid anthropogenic rise in CO2. 相似文献
18.
Landsat 7s recent malfunctioning will result in significant gaps in long-term satellite monitoring of Earth, affecting not only the research of the Earth science community but also conservation users of these data. To determine whether or how important Landsat monitoring is for conservation and natural resource management, we reviewed the Landsat programs history with special emphasis on the development of user groups. We also conducted a bibliographic search to determine the extent to which conservation research has been based on Landsat data. Conservation biologists were not an early user group of Landsat data because a) biologists lacked technical capacity – computers and software – to analyze these data; b) Landsats 1980s commercialization rendered images too costly for biologists budgets; and c) the broad-scale disciplines of conservation biology and landscape ecology did not develop until the mid-to-late 1980s. All these conditions had changed by the 1990s and Landsat imagery became an important tool for conservation biology. Satellite monitoring and Landsat continuity are mandated by the Land Remote Sensing Act of 1992. This legislation leaves open commercial options. However, past experiments with commercial operations were neither viable nor economical, and severely reduced the quality of monitoring, archiving and data access for academia and the public. Future satellite monitoring programs are essential for conservation and natural resource management, must provide continuity with Landsat, and should be government operated. 相似文献
19.
滨州沿海湿地生物多样性保护探讨 总被引:1,自引:0,他引:1
重点研究了该区域海洋生物多样性、淡水生物多样性、陆生和海岛等高等植物多样性、陆栖动物多样性与特点。分析了其破坏现状及原因,提出了生物多样性保护对策和可持续利用途径。 相似文献
20.
植物遗传资源保护与利用的市场化机制和国际制度 总被引:9,自引:0,他引:9
随着植物物种资源的不断减少和因生物技术迅猛发展对植物遗传资源需求的不断增加 ,植物遗传资源正逐步由公共物品转变为稀缺物品。坚持《生物多样性公约》所确立的遗传资源效益公平分享原则 ,完善现有国际多边体系 ,促进以“遗传编码功能”价值概念和遗传资源保护效应“内部化”与“补偿”方案为基础的植物遗传资源市场化保护与利用机制的形成 ,建立“植物遗传资源交易所”和“生物多样性合作社” ,将有助于提高世界各国尤其是发展中国家保护植物遗传资源的积极性 ,实现全球植物遗传资源的可持续利用 相似文献