全文获取类型
收费全文 | 2359篇 |
免费 | 70篇 |
国内免费 | 30篇 |
专业分类
安全科学 | 102篇 |
废物处理 | 108篇 |
环保管理 | 516篇 |
综合类 | 273篇 |
基础理论 | 664篇 |
环境理论 | 9篇 |
污染及防治 | 512篇 |
评价与监测 | 169篇 |
社会与环境 | 78篇 |
灾害及防治 | 28篇 |
出版年
2023年 | 22篇 |
2022年 | 42篇 |
2021年 | 57篇 |
2020年 | 34篇 |
2019年 | 54篇 |
2018年 | 67篇 |
2017年 | 81篇 |
2016年 | 107篇 |
2015年 | 73篇 |
2014年 | 90篇 |
2013年 | 203篇 |
2012年 | 124篇 |
2011年 | 167篇 |
2010年 | 105篇 |
2009年 | 130篇 |
2008年 | 132篇 |
2007年 | 119篇 |
2006年 | 131篇 |
2005年 | 72篇 |
2004年 | 64篇 |
2003年 | 73篇 |
2002年 | 59篇 |
2001年 | 35篇 |
2000年 | 50篇 |
1999年 | 31篇 |
1998年 | 26篇 |
1997年 | 18篇 |
1996年 | 25篇 |
1995年 | 26篇 |
1994年 | 22篇 |
1993年 | 16篇 |
1992年 | 15篇 |
1991年 | 15篇 |
1990年 | 10篇 |
1989年 | 14篇 |
1988年 | 13篇 |
1987年 | 10篇 |
1986年 | 16篇 |
1985年 | 11篇 |
1984年 | 5篇 |
1983年 | 11篇 |
1982年 | 17篇 |
1981年 | 18篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1978年 | 9篇 |
1977年 | 4篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1969年 | 4篇 |
排序方式: 共有2459条查询结果,搜索用时 15 毫秒
51.
52.
Robert A. Montgomery Madeline Carr Charlie R. Booher Abigail M. Pointer Brendan M. Mitchell Natalie Smith Keegan Calnan Georgina M. Montgomery Mordecai Ogada Daniel B. Kramer 《Conservation biology》2020,34(4):915-924
In November 1928, Theodore Jr. and Kermit Roosevelt led an expedition to China with the expressed purpose of being the first Westerners to kill the giant panda (Ailuropoda melanoleuca). The expedition lasted 8 months and resulted in the brothers shooting a giant panda in the mountains of Sichuan Province. Given the concurrent attention in the popular press describing this celebrated expedition, the giant panda was poised to be trophy hunted much like other large mammals around the world. Today, however, the killing of giant pandas, even for the generation of conservation revenue, is unthinkable for reasons related to the species itself and the context, in time and space, in which the species was popularized in the West. We found that the giant panda's status as a conservation symbol, exceptional charisma and gentle disposition, rarity, value as a nonconsumptive ecotourism attraction, and endemism are integral to the explanation of why the species is not trophy hunted. We compared these intrinsic and extrinsic characteristics with 20 of the most common trophy-hunted mammals to determine whether the principles applying to giant pandas are generalizable to other species. Although certain characteristics of the 20 trophy-hunted mammals aligned with the giant panda, many did not. Charisma, economic value, and endemism, in particular, were comparatively unique to the giant panda. Our analysis suggests that, at present, exceptional characteristics may be necessary for certain mammals to be excepted from trophy hunting. However, because discourse relating to the role of trophy hunting in supporting conservation outcomes is dynamic in both science and society, we suspect these valuations will also change in future. 相似文献
53.
Balsalobre-Lorente Daniel Driha Oana M. Shahbaz Muhammad Sinha Avik 《Environmental science and pollution research international》2020,27(7):7130-7144
Environmental Science and Pollution Research - This paper focuses on long-term evidence on economic growth, international tourism, globalization, energy consumption and carbon dioxide (CO2)... 相似文献
54.
A study was conducted in November 1999 to assess sediment quality and condition of benthic fauna in the Neuse River Estuary (NRE), North Carolina, USA, following the passage of three Atlantic hurricanes during the two months prior. Samples for analysis of macroinfauna (>0.5 mm sieve size), chemical contamination of sediments, and other abiotic environmental variables (salinity, dissolved oxygen, pH, depth, sediment granulometry) were collected at 20 sites from the mouth of the Neuse River at Pamlico Sound to approximately 90 km upstream. Results were compared to those obtained from the same area in July 1998 using similar protocols. Depressed salinity, caused by extreme rainfall and associated high freshwater flow, persisted throughout much of the estuary, which had experienced periods of water-column stratification and hypoxia of underlying waters. Fifteen of the 20 sites, representing 299 km2 (76% of the survey area), also showed signs of benthic stress based on a multi-metric benthic index of biotic integrity (B-IBI). Benthic impacts included reductions in the abundance, diversity, and numbers of species and shifts in taxonomic composition, with a notable increase in dominance of the opportunistic polychaete Mediomastus ambiseta as other former dominant species declined. There was no significant increase in the extent of chemical contamination compared to pre-hurricane conditions. Storm-related reductions in dissoved oxygen and salinity were the more likely causes of the observed benthic impacts, though it was not possible, based on these results, to separate storm effects from seasonal changes in the benthos and annual episodes of summer anoxia and hypoxia. 相似文献
55.
Archambault DJ Li X Foster KR Jack TR 《Environmental monitoring and assessment》2006,115(1-3):509-530
Ethephon, which releases ethylene within plant tissues after application, was chosen to perform assessments of the relative sensitivity of crops to ethylene and to determine which stages of plant development were most sensitive. The species chosen were: barley, wheat, oats, canola and field pea, all of which are important crops in the province of Alberta, Canada. Plants were treated with ethephon at one of 7 different stages. Plants were assessed for their vegetative and reproductive growth, including height, biomass, yield and seed quality. Visual symptoms were photographed and documented to compare them with symptoms caused by ethylene applied as a gas. It was concluded that in barley, wheat and canola the late vegetative and early reproductive stages were most sensitive, at least when sensitivity was defined as reductions in yield and quality. As for field pea, ethephon had no effect on yield but did cause increased numbers of pods, which in certain conditions could lead to increased yields. Significant effects on vegetative growth were only observed in the early vegetative stages of development but with no effects on yield. The screening protocol successfully identified sensitive cultivars and growth stages for further investigation of the effects of ethylene exposure. 相似文献
56.
The regional-scale importance of an aquatic stressor depends both on its regional extent (i.e., how widespread it is) and
on the severity of its effects in ecosystems where it is found. Sample surveys, such as those developed by the U.S. Environmental
Protection Agency’s Environmental Monitoring and Assessment Program (EMAP), are designed to estimate and compare the extents,
throughout a large region, of elevated conditions for various aquatic stressors. In this article, we propose relative risk
as a complementary measure of the severity of each stressor’s effect on a response variable that characterizes aquatic ecological
condition. Specifically, relative risk measures the strength of association between stressor and response variables that can
be classified as either “good” (i.e., reference) or “poor” (i.e., different from reference). We present formulae for estimating
relative risk and its confidence interval, adapted for the unequal sample inclusion probabilities employed in EMAP surveys.
For a recent EMAP survey of streams in five Mid-Atlantic states, we estimated the relative extents of eight stressors as well
as their relative risks to aquatic macroinvertebrate assemblages, with assemblage condition measured by an index of biotic
integrity (IBI). For example, a measure of excess sedimentation had a relative risk of 1.60 for macroinvertebrate IBI, with
the meaning that poor IBI conditions were 1.6 times more likely to be found in streams having poor conditions of sedimentation
than in streams having good sedimentation conditions. We show how stressor extent and relative risk estimates, viewed together,
offer a compact and comprehensive assessment of the relative importances of multiple stressors. 相似文献
57.
Coastal waters have been significantly influenced by increased inputs of nutrients that have accompanied population growth
in adjacent drainage basins. In Tampa Bay, Florida, USA, the population has quadrupled since 1950. By the late 1970s, eutrophic
conditions including phytoplankton and macroalgal blooms and seagrass losses were evident. The focus of improving Tampa Bay
is centered on obtaining sufficient water quality necessary for restoring seagrass habitat, estimated to have been 16,400
ha in 1950 but reduced to 8800 ha by 1982. To address these problems, targets for nutrient load reductions along with seagrass
restoration goals were developed and actions were implemented to reach adopted targets. Empirical regression models were developed
to determine relationships between chlorophyll a concentrations and light attenuation adequate for sustainable seagrass growth. Additional empirical relationships between
nitrogen loading and chlorophyll a concentrations were developed to determine how Tampa Bay responds to changes in loads. Data show that when nitrogen load
reduction and chlorophyll a targets are met, seagrass cover increases. After nitrogen load reductions and maintenance of chlorophyll a at target levels, seagrass acreage has increased 25% since 1982, although more than 5000 ha of seagrass still require recovery.
The cooperation of scientists, managers, and decision makers participating in the Tampa Bay Estuary Program’s Nitrogen Management
Strategy allows the Tampa Bay estuary to continue to show progress towards reversing many of the problems that once plagued
its waters. These results also highlight the importance of a multi-entity watershed management process in maintaining progress
towards science-based natural resource goals. 相似文献
58.
Keith Worrall Anthony Newton Clive Robinson Ramesh Rao 《环境化学》2006,25(5):661-663
"二噁英"是指一类化学结构和生物特征均有某些相似之处的化合物.这些有毒化合物有几百种,可分为相关的三大类:氯代二苯并-对-二噁英(CDDs),氯代二苯并呋喃(CDFs)和某些多氯代联苯(PCBs).CDDs和CDFs并非与生具有,而是由于人类活动不注意而生成的.天然过程也会产生CDDs和CDFs. 相似文献
59.
Carbon and nitrogen mineralization rates after application of organic amendments to soil 总被引:1,自引:0,他引:1
The objective of this study was to quantify C and N mineralization rates from a range of organic amendments that differed in their total C and N contents and C quality, to gain a better understanding of their influence on the soil N cycle. A pelletized poultry manure (PP), two green waste-based composts (GWCa, GWCb), a straw-based compost (SBC), and a vermi-cast (VER) were incubated in a coarse-textured soil at 15 degrees C for 142 d. The C quality of each amendment was determined by chemical analysis and by 13C nuclear magnetic resonance (NMR). Carbon dioxide (CO2-C) evolution was determined using alkali traps. Gross N mineralization rates were calculated by 15N isotopic pool dilution. The CO2-C evolution rates and gross N mineralization rates were generally higher in amended soils than in the control soil. With the exception of GWCb all amendments released inorganic N at concentrations that would be high enough to warrant a reduction in inorganic N fertilizer application rates. The amount of N released from PP was high indicating that application rates should be reduced, or alternative amendments used, to minimize leaching losses in regions where ground water quality is of concern. There was a highly significant relationship between CO2-C evolution and gross N mineralization (R2= 0.95). Some of the chemically determined C quality parameters had significant relationships (p < 0.05) with both the cumulative amounts of C and N evolved. However, we found no significant relationships between 13C NMR spectral groupings, or their ratios, and either the CO2-C evolved or gross N mineralized from the amendments. 相似文献
60.
Effect of sulfate on the methanogenic activity of a bacterial culture from a
brewery wastewater during glucose degradation 总被引:2,自引:1,他引:1
Nusara Sinbuathong Sutha Khaodhiar Winai Liengcharernsit Pramote Sirirote Daniel Watts 《环境科学学报(英文版)》2007,19(9):1025-1027
The maximum specific methanogenic activity (SMA) of a sludge originating from a brewery wastewater treatment plant on the degradation of glucose was investigated at various levels of sulfate on a specific loading basis. Batch experiments were conducted in serum bottles at pH 7 and 35℃. A comparison of the values indicates that the SMA of this mixed culture was increased and reached its highest level of 0.128 g CH4 gas COD/(g VSS.d) when biomass was in contact with sulfate at a ratio of 1:0.114 by weight. 相似文献