全文获取类型
收费全文 | 6077篇 |
免费 | 132篇 |
国内免费 | 63篇 |
专业分类
安全科学 | 266篇 |
废物处理 | 211篇 |
环保管理 | 1366篇 |
综合类 | 773篇 |
基础理论 | 1508篇 |
环境理论 | 11篇 |
污染及防治 | 1461篇 |
评价与监测 | 358篇 |
社会与环境 | 252篇 |
灾害及防治 | 66篇 |
出版年
2023年 | 29篇 |
2022年 | 38篇 |
2021年 | 66篇 |
2020年 | 50篇 |
2019年 | 68篇 |
2018年 | 129篇 |
2017年 | 132篇 |
2016年 | 177篇 |
2015年 | 142篇 |
2014年 | 157篇 |
2013年 | 541篇 |
2012年 | 259篇 |
2011年 | 353篇 |
2010年 | 269篇 |
2009年 | 295篇 |
2008年 | 310篇 |
2007年 | 351篇 |
2006年 | 327篇 |
2005年 | 227篇 |
2004年 | 216篇 |
2003年 | 202篇 |
2002年 | 203篇 |
2001年 | 119篇 |
2000年 | 101篇 |
1999年 | 92篇 |
1998年 | 88篇 |
1997年 | 97篇 |
1996年 | 88篇 |
1995年 | 106篇 |
1994年 | 88篇 |
1993年 | 69篇 |
1992年 | 54篇 |
1991年 | 52篇 |
1990年 | 57篇 |
1989年 | 34篇 |
1988年 | 43篇 |
1987年 | 39篇 |
1986年 | 54篇 |
1985年 | 38篇 |
1984年 | 53篇 |
1983年 | 49篇 |
1982年 | 47篇 |
1981年 | 44篇 |
1980年 | 34篇 |
1979年 | 38篇 |
1978年 | 25篇 |
1977年 | 20篇 |
1976年 | 12篇 |
1974年 | 15篇 |
1972年 | 15篇 |
排序方式: 共有6272条查询结果,搜索用时 15 毫秒
691.
Monica E. Wright Dean B. Atkinson Luke Ziemba Robert Griffin Naruki Hiranuma Sarah Brooks Barry Lefer James Flynn Ryan Perna Bernhard Rappenglück Winston Luke Paul Kelley 《Atmospheric environment (Oxford, England : 1994)》2010,44(33):4035-4044
Extensive aerosol optical properties, particle size distributions, and Aerodyne quadrupole aerosol mass spectrometer measurements collected during TRAMP/TexAQS 2006 were examined in light of collocated meteorological and chemical measurements. Much of the evident variability in the observed aerosol-related air quality is due to changing synoptic meteorological situations that direct emissions from various sources to the TRAMP site near the center of the Houston-Galveston-Brazoria (HGB) metropolitan area. In this study, five distinct long-term periods have been identified. During each of these periods, observed aerosol properties have implications that are of interest to environmental quality management agencies. During three of the periods, long range transport (LRT), both intra-continental and intercontinental, appears to have played an important role in producing the observed aerosol. During late August 2006, southerly winds brought super-micron Saharan dust and sea salt to the HGB area, adding mass to fine particulate matter (PM2.5) measurements, but apparently not affecting secondary particle growth or gas-phase air pollution. A second type of LRT was associated with northerly winds in early September 2006 and with increased ozone and sub-micron particulate matter in the HGB area. Later in the study, LRT of emissions from wildfires appeared to increase the abundance of absorbing aerosols (and carbon monoxide and other chemical tracers) in the HGB area. However, the greatest impacts on Houston PM2.5 air quality are caused by periods with low-wind-speed sea breeze circulation or winds that directly transport pollutants from major industrial areas, i.e., the Houston Ship Channel, into the city center. 相似文献
692.
Lena Maria Nilsson Georgia Destouni James Berner Alexey A. Dudarev Gert Mulvad Jon Øyvind Odland Alan Parkinson Constantine Tikhonov Arja Rautio Birgitta Evengård 《Ambio》2013,42(7):816-822
This perspective paper argues for an urgent need to monitor a set of 12 concrete, measurable indicators of food and water security in the Arctic over time. Such a quantitative indicator approach may be viewed as representing a reductionist rather than a holistic perspective, but is nevertheless necessary for actually knowing what reality aspects to monitor in order to accurately understand, quantify, and be able to project critical changes to food and water security of both indigenous and non-indigenous people in the Arctic. More relevant indicators may be developed in the future, taking us further toward reconciliation between reductionist and holistic approaches to change assessment and understanding. However, the potential of such further development to improved holistic change assessment is not an argument not to urgently start to monitor and quantify the changes in food and water security indicators that are immediately available and adequate for the Arctic context. 相似文献
693.
694.
In partnership with the US Department of Energy’s Office of Industrial Technology, Whyco Technologies, Inc., has developed an innovative perforated plating barrel used in the plating of metal parts. This new technology employs a thin-walled construction, differing from the traditional thick-wall design required to provide adequate structural integrity. The thicker walls lowered the efficiency of transferring plating solution into and out of the barrel and diminished the electrical current pushed through the holes and onto the parts being plated. By machining pockets out of the traditional thick-walled perforated structure, Whyco produced a ‘honeycomb’ of staggered cells, allowing for the greatest number of holes per open area while maintaining structural integrity. Hydrodynamic pumping occurs during barrel rotation to create greater solution transfer than in traditional barrels. The Whyco barrel has higher current density plating, which leads to faster plating cycles, reduced bath concentration, and better plating of difficult chemistries such as in alloys. This new technology has helped the company reduce energy use by 16%, eliminate more than 480 tons/year of solid waste, and reduce wastewater by more than 17 000 gallons/day. The resulting cost savings total more than $500 000 annually. The company has manufactured and sold more than 275 of these barrels to other electroplating companies that are reporting up to a 40% increase in plating productivity and similar energy and environmental impacts. 相似文献
695.
696.
697.
Incentives for Biological Conservation: Costa Rica's Private Wildlife Refuge Program 总被引:3,自引:1,他引:2
Abstract: The alarming pace of tropical biodiversity loss requires development of innovative approaches for in situ biodiversity conservation. Incentive-based approaches have emerged as one possible option. We interviewed 68 private nature reserve owners to learn more about one of Costa Rica's incentive programs. The interview group included all reserve owners participating in the government's Private Wildlife Refuge Program (n = 22) and a control group of nonparticipating owners (n = 46). Quantitative and qualitative data led to seven main conclusions on the use of incentive programs: (1) a developing country can expand and enhance its formal park system through conservation incentives; (2) insufficient promotion, and resulting information gaps, can prevent an incentive program from realizing its full potential; (3) landowners enter a program not only in response to the intended incentive package, but also for several powerful and hidden incentives such as publicity and marketing purposes; (4) underutilization of official incentives by participants, in part due to sporadic delivery of incentives by the government, can undermine program effectiveness; (5) biodiversity protection goals can be accomplished by means of a wide range of incentives; (6) programs that require only a short-term commitment by landowners can still lead to long-term biodiversity protection; and ( 7) a program can produce unanticipated negative consequences at the national level, including putting conservation at odds with social justice. These and other lessons on the use of incentives should be of interest wherever biodiversity is threatened, wherever new conservation partners are being sought, and wherever incentive-based approaches are being considered. 相似文献
698.
699.
700.
A marked decline in the contribution by Marovo Lagoon to the annual total bêche-de-mer production of the Solomon Islands from
58% in 1989 to 17% in 2003 prompted investigation of their current biomass and diversity. We also assessed changes to critical
ecological services and the prospects for population recovery following a fisheries closure. Day time and nocturnal transects
revealed a mean abundance of 32.4 (SD = 5.3) low value species per ha (e.g. Holothuria atra, H. edulis, H. coluber and Thelenota anax) and 15.2 (SD = 2.7) high value species per ha (e.g. H. fuscogilva, Actinopyga lecanora, Stichopus hermanni and Thelenota ananas). Following a 17 month closure of the fishery (2005–2007), the abundance of bêche-de-mer was reported by local fisherman
to have increased; however, no scientific studies were conducted that can substantiate this community held belief. The current
study aimed to document the impact of re-opening the fishery in 2007 and documented a decline in high value species of 9%
over a 5 month period following the opening of the fishery, while low value species continued to increase in abundance by
11%, over the same period based on nocturnal surveys. Continued observation of the recovery, post closure, and any subsequent
harvest in Marovo will be required to properly understand population dynamics and provide a sustainable harvest plan for bêche-de-mer
in the future. 相似文献