全文获取类型
收费全文 | 20936篇 |
免费 | 124篇 |
国内免费 | 106篇 |
专业分类
安全科学 | 282篇 |
废物处理 | 1291篇 |
环保管理 | 2609篇 |
综合类 | 2299篇 |
基础理论 | 6202篇 |
环境理论 | 4篇 |
污染及防治 | 4574篇 |
评价与监测 | 1777篇 |
社会与环境 | 2076篇 |
灾害及防治 | 52篇 |
出版年
2023年 | 47篇 |
2022年 | 106篇 |
2021年 | 88篇 |
2020年 | 70篇 |
2019年 | 81篇 |
2018年 | 1711篇 |
2017年 | 1615篇 |
2016年 | 1477篇 |
2015年 | 311篇 |
2014年 | 267篇 |
2013年 | 774篇 |
2012年 | 796篇 |
2011年 | 1891篇 |
2010年 | 1197篇 |
2009年 | 1083篇 |
2008年 | 1500篇 |
2007年 | 1894篇 |
2006年 | 442篇 |
2005年 | 466篇 |
2004年 | 381篇 |
2003年 | 516篇 |
2002年 | 514篇 |
2001年 | 530篇 |
2000年 | 345篇 |
1999年 | 201篇 |
1998年 | 169篇 |
1997年 | 131篇 |
1996年 | 138篇 |
1995年 | 172篇 |
1994年 | 128篇 |
1993年 | 107篇 |
1992年 | 125篇 |
1991年 | 120篇 |
1990年 | 135篇 |
1989年 | 133篇 |
1988年 | 97篇 |
1987年 | 91篇 |
1986年 | 71篇 |
1985年 | 92篇 |
1984年 | 106篇 |
1983年 | 96篇 |
1982年 | 82篇 |
1981年 | 74篇 |
1980年 | 61篇 |
1979年 | 69篇 |
1977年 | 53篇 |
1976年 | 48篇 |
1975年 | 54篇 |
1974年 | 52篇 |
1973年 | 53篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
Nicole Shumway Megan I. Saunders Sam Nicol Richard A. Fuller Noam Ben-Moshe Takuya Iwamura Sun W. Kim Nicholas J. Murray James E. M. Watson Martine Maron 《Conservation biology》2023,37(2):e14031
Biodiversity offsets aim to counterbalance the residual impacts of development on species and ecosystems. Guidance documents explicitly recommend that biodiversity offset actions be located close to the location of impact because of higher potential for similar ecological conditions, but allowing greater spatial flexibility has been proposed. We examined the circumstances under which offsets distant from the impact location could be more likely to achieve no net loss or provide better ecological outcomes than offsets close to the impact area. We applied a graphical model for migratory shorebirds in the East Asian–Australasian Flyway as a case study to explore the problems that arise when incorporating spatial flexibility into offset planning. Spatially flexible offsets may alleviate impacts more effectively than local offsets; however, the risks involved can be substantial. For our case study, there were inadequate data to make robust conclusions about the effectiveness and equivalence of distant habitat-based offsets for migratory shorebirds. Decisions around offset placement should be driven by the potential to achieve equivalent ecological outcomes; however, when considering more distant offsets, there is a need to evaluate the likely increased risks alongside the potential benefits. Although spatially flexible offsets have the potential to provide more cost-effective biodiversity outcomes and more cobenefits, our case study showed the difficulty of demonstrating these benefits in practice and the potential risks that need to be considered to ensure effective offset placement. 相似文献
2.
Nicholas J. Georgiadis Joel E. Baker 《Journal of the American Water Resources Association》2023,59(5):970-983
In Pacific Northwest streams, summer low flows limit water available to competing instream (salmon) and out-of-stream (human) uses, creating broad interest in how and why low flows are trending. Analyses that assumed linear (monotonic) change over the last ~60 years revealed declining low flow trends in minimally disturbed streams. Here, polynomials were used to model flow trends between 1929 and 2015. A multidecadal oscillation was observed in flows, which increased initially from the 1930s until the 1950s, declined until the 1990s, and then increased again. A similar oscillation was detected in precipitation series, and opposing oscillations in surface temperature, Pacific Decadal Oscillation, and Interdecadal Pacific Oscillation series. Multidecadal oscillations with similar periods to those described here are well known in climate indices. Fitted model terms were consistent with flow trends being influenced by at least two drivers, one oscillating and the other monotonic. Anthropogenic warming is a candidate driver for the monotonic decline, and variation in (internal) climatic circulation for the oscillating trend, but others were not ruled out. The recent upturn in streamflows suggests that anthropogenic warming has not been the dominant factor driving streamflow trends, at least until 2015. Climate projections based on simulations that omit drivers of multidecadal variation are likely to underestimate the range, and rate of change, of future climatic variation. 相似文献
3.
Conservation decisions are invariably made with incomplete data on species’ distributions, habitats, and threats, but frameworks for allocating conservation investments rarely account for missing data. We examined how explicit consideration of missing data can boost return on investment in ecosystem restoration, focusing on the challenge of restoring aquatic ecosystem connectivity by removing dams and road crossings from rivers. A novel way of integrating the presence of unmapped barriers into a barrier optimization model was developed and applied to the U.S. state of Maine to maximize expected habitat gain for migratory fish. Failing to account for unmapped barriers during prioritization led to nearly 50% lower habitat gain than was anticipated using a conventional barrier optimization approach. Explicitly acknowledging that data are incomplete during project selection, however, boosted expected habitat gains by 20–273% on average, depending on the true number of unmapped barriers. Importantly, these gains occurred without additional data. Simply acknowledging that some barriers were unmapped, regardless of their precise number and location, improved conservation outcomes. Given incomplete data on ecosystems worldwide, our results demonstrate the value of accounting for data shortcomings during project selection. 相似文献
4.
Venkatesan G. Subramani T. Karunanidhi D. Sathya U. Li Peiyue 《Environmental science and pollution research international》2021,28(15):18552-18552
Environmental Science and Pollution Research - A Correction to this paper has been published: https://doi.org/10.1007/s11356-021-13406-7 相似文献
5.
Markad Adinath T. Landge Asha T. Nayak Binaya B. Inamdar Arun B. Mishra Akhil K. 《Environmental science and pollution research international》2021,28(24):31013-31031
Environmental Science and Pollution Research - With the use of different multivariate statistical analysis methods, spatio-temporal fluctuations in the water parameters of Tiru reservoir located at... 相似文献
6.
In this laboratory study different combinations of bed (sand, pebble gravel [gravel], and a mix of sand and gravel) and flow (typical and overtopping) were experimented with to investigate the impact of porous deflectors in flow diversity, water quality, and fish performance in prismatic open channels. Deflectors changed the gradually varied flow to a rapidly varied flow, as a sudden change in the water depth was observed at the deflectors, and this change was large for smooth beds. With the presence of gravel, the scouring near the downstream deflector was almost twice that of the sand bed, and with the scouring at its own upstream deflector, irrespective of whether the flow was typical or overtopping. This behavior was a result of sand mobilization due to shear stress and sand mobilization aided gravel transport. The mixed bed showed less gravel movement compared to the gravel-only bed. The percentage of sediment washed out was minor for all bed scenarios, indicating that sediment transport was local. Relative to the sand bed without deflectors (representing a typical urban canal), deflectors resulted in reduced and improved water quality (in terms of sediment load) for sand, and mixed bed, respectively. The fishes found refuge and were comfortable in the pool areas created by deflectors unlike in channels without deflectors where they showed exhaustion. 相似文献
7.
Du Jiaxin Waite T. David Feng Jing Lei Yang Tang Wangwang 《Environmental Chemistry Letters》2023,21(2):885-909
Environmental Chemistry Letters - Declining mineral resources, high fertilizer production cost and widespread eutrophication are calling for the recovery of nitrogen and phosphorus from wastewaters... 相似文献
8.
Carly E. Federman Durelle T. Scott Erich T. Hester 《Journal of the American Water Resources Association》2023,59(1):29-48
River flooding impacts human life and infrastructure, yet provides habitat and ecosystem services. Traditional flood control (e.g., levees, dams) reduces habitat and ecosystem services, and exacerbates flooding elsewhere. Floodplain restoration (i.e., bankfull floodplain reconnection and Stage 0) can also provide flood management, but has not been sufficiently evaluated for small frequent storms. We used 1D unsteady Hydrologic Engineering Center's River Analysis System to simulate small storms in a 5 km-long, second-order generic stream from the Chesapeake Bay watershed, and varied % channel restored (starting at the upstream end), restoration location, restoration bank height (distinguishes bankfull from Stage 0 restoration), and floodplain width/Manning's n. Stream restoration decreased (attenuated) peak flow up to 37% and increased floodplain exchange by up to 46%. Floodplain width and % channel restored had the largest impact on flood attenuation. The incremental effects of new restoration projects on flood attenuation were greatest when little prior restoration had occurred. By contrast, incremental effects on floodplain exchange were greatest in the presence of substantial prior restoration, setting up a tradeoff. A similar tradeoff was revealed between attenuation and exchange for project location, but not bank height or floodplain width. In particular, attenuation and exchange were always greater for Stage 0 than for bankfull floodplain restoration. Stage 0 thus may counteract human impacts such as urbanization. 相似文献
9.
Péter Török 《Conservation biology》2018,32(1):249-250
10.
Travis O. Brenden Reneé Reilly Edward Eisch Aaron Switzer Gary E. Whelan 《Environmental monitoring and assessment》2018,190(7):430
Effective water quality management depends on enactment of appropriately designed monitoring programs to reveal current and forecasted conditions. Because water quality conditions are influenced by numerous factors, commonly measured attributes such as total phosphorus (TP) can be highly temporally varying. For highly varying processes, monitoring programs should be long-term and periodic quantitative analyses are needed so that temporal trends can be distinguished from stochastic variation, which can yield insights into potential modifications to the program. Using generalized additive mixed modeling, we assessed temporal (yearly and monthly) trends and quantified other sources of variation (daily and subsampling) in TP concentrations from a multidecadal depth-specific monitoring program on Big Platte Lake, Michigan. Yearly TP concentrations decreased from the late 1980s to late 1990s before rebounding through the early 2000s. At depths of 2.29 to 13.72 m, TP concentrations have cycled around stationary points since the early 2000s, while at the surface and depths ≥?18.29 concentrations have continued declining. Summer and fall peaks in TP concentrations were observed at most depths, with the fall peak at deeper depths occurring 1 month earlier than shallower depths. Daily sampling variation (i.e., variation within a given month and year) was greatest at shallowest and deepest depths. Variation in subsamples collected from depth-specific water samples constituted a small fraction of total variation. Based on model results, cost-saving measures to consider for the monitoring program include reducing subsampling of depth-specific concentrations and reducing the number of sampling depths given observed consistencies across the program period. 相似文献