全文获取类型
收费全文 | 1562篇 |
免费 | 145篇 |
国内免费 | 316篇 |
专业分类
安全科学 | 130篇 |
废物处理 | 12篇 |
环保管理 | 259篇 |
综合类 | 934篇 |
基础理论 | 250篇 |
环境理论 | 1篇 |
污染及防治 | 82篇 |
评价与监测 | 91篇 |
社会与环境 | 158篇 |
灾害及防治 | 106篇 |
出版年
2024年 | 6篇 |
2023年 | 31篇 |
2022年 | 57篇 |
2021年 | 58篇 |
2020年 | 47篇 |
2019年 | 53篇 |
2018年 | 49篇 |
2017年 | 68篇 |
2016年 | 78篇 |
2015年 | 86篇 |
2014年 | 63篇 |
2013年 | 107篇 |
2012年 | 130篇 |
2011年 | 139篇 |
2010年 | 100篇 |
2009年 | 78篇 |
2008年 | 71篇 |
2007年 | 86篇 |
2006年 | 106篇 |
2005年 | 81篇 |
2004年 | 67篇 |
2003年 | 75篇 |
2002年 | 48篇 |
2001年 | 35篇 |
2000年 | 51篇 |
1999年 | 44篇 |
1998年 | 29篇 |
1997年 | 34篇 |
1996年 | 34篇 |
1995年 | 19篇 |
1994年 | 14篇 |
1993年 | 14篇 |
1992年 | 14篇 |
1991年 | 9篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1977年 | 3篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有2023条查询结果,搜索用时 31 毫秒
991.
中国南部沿海地区雨涝灾害时空特征及趋势预测 总被引:1,自引:1,他引:1
根据插补完整的近500年旱涝等级序列和近40年实测降水资料,分别制定了历史时期和观测时期雨涝分级标准。建立了五省一市18个站的雨涝序列。在此基础上,探讨了中国南部沿海地区雨涝分布时空特征,并对典型雨涝年的成因及灾情进行了分析和评估,最后作出90年代雨涝趋势预测,为沿海的减灾、防灾提供科学依据 相似文献
992.
Oscar L. Paulson George F. Pessoney Harold Battalora Randall Williams John Eastman Gary Pruitt 《Journal of the American Water Resources Association》1977,13(2):341-348
ABSTRACT: A study of residential canal system on the Mississippi Gulf Coast and adjacent natural water bodies was conducted to determine the relationship in flushing characteristics between man-made and natural systems. The comparison was based on measurements of temperature, salinity, conductivity, coliform, pH, transparency, biological oxidation demand, dissolved oxygen, bathymetry, tides, water velocity, and Rhodamine dye concentrations. The results indicate that coliform bacteria increase with increasing distance of stations from St. Louis Bay and dissolved oxygen decreases in a similar manner. Biological oxidation demand was low at all stations; showing no differences between natural and man-made systems. The canal system Studied was shallower than adjacent water bodies and water velocities in the canal system are a function of tidal amplitude while velocities in the river are affected by both tides and runoff. The other parameters measured show little or no differences between natural and man-made systems, but reflect overall seasonal changes. Flushing rates between the residential canal systems and an adjacent natural system are equivalent on the basis of decline in dye concentrations measured over a five-day period. 相似文献
993.
E. W. Shows 《Journal of the American Water Resources Association》1977,13(5):973-982
ABSTRACT: This paper presents evidence that currently published flood insurance premiums may be insufficient to cover expected losses in coastal areas subject to hurricane. The problems of developing flood premiums in coastal zones are discussed and Federal Insurance Administration (FIA) reaction to these problems analyzed. Flood losses in the coastal zone of Bay County, Florida due to hurricane Eloise are compared with losses which would be predicted by the FIA. This comparison raises important questions concerning the adequacy of flood premiums in coastal zones and the undesirable indirect effects that underpricing flood risk will have on location decisions in the coastal floodplain. 相似文献
994.
Carolyn E. Gombert Stephen T. Lancaster Gordon E. Grant Rebecca L. Flitcroft 《Journal of the American Water Resources Association》2023,59(4):615-634
In the Willamette River, OR, main channel temperatures can be too warm for cold water fishes, causing fish to concentrate in secondary channel features that provide thermal refugia. However, temperature regimes vary among and within features. Improved understanding of physical processes controlling thermal regimes is needed. This study developed a dimensionless index for assessment of thermal refugia on the upper Willamette River. The novel hyporheic insolation (HIN) index uses minimal field measurements to predict thermal refugia resulting from buffering. Continuous water temperature measurements at one side channel, eight alcoves, and six beaver ponds provided data to ground truth calculated predictions. Water temperature records were first used to characterize stratification at sites. Calculation of the Richardson number, an index of stability, showed two well-mixed sites and 13 stratified sites. At stratified sites, calculated values characterized the ratio of cooling flux from hyporheic discharge to heat flux from incoming solar radiation. As increased, measured temperatures at sites decreased. Despite overall scatter, a logarithmic fit to bin-averaged values showed R2 = 0.91. Calculations suggest that secondary channel features characterized by stratification and cool hyporheic discharge can provide thermal refugia. Accordingly, the HIN index may serve as a practical tool grounded in physical processes governing temperature across a floodplain. 相似文献
995.
PaulR. Wolf Terrence J. Keating 《Journal of the American Water Resources Association》1973,9(2):312-319
ABSTRACT Necessary input parameters for studying mixing zone characteristics of thermal plumes are horizontal surface and subsurface water velocities. Using time lapse aerial photography and analytical photogrammetric techniques, movements of drogues in an effluent plume were traced. From these traces accurate velocity vectors were obtained. Photographic coordinates of drogue images were measured using a glass scale. From the photo coordinates and the results of a ground control survey, an analytical solution was made for positions of drogues in the water at known intervals of time. Drogue positions were mapped for selected exposures thereby providing a visual display of velocity vectors in the study area. A rigorous error analysis was performed to determine the validity of the computed results. 相似文献
996.
C W. Fetter 《Journal of the American Water Resources Association》1972,8(6):1173-1176
The traditional factors used to determine safe yield of a groundwater basin (water supply, economics, water quality and water rights) do not include environmental effects. Because of the unique estuarine ecosystems associated with many coastal aquifers, environmental effects should be included in the determination of the safe yield of these aquifers. Controlled saline-water intrusion should be considered as a management tool in coastal aquifers. Artificial aquifer recharge using treated wastewater may be used to increase the safe yield of a coastal aquifer system while preserving the ecology of the coastal ecosystems. 相似文献
997.
An extensive road system with rapidly increasing traffic produces diverse ecological effects that cover a large land area.
Our objective was to evaluate the effect of roads with different traffic volumes on surrounding avian distributions, and its
importance relative to other variables. Grassland bird data (5 years) for 84 open patches in an outer suburban/rural landscape
near Boston were analyzed relative to: distance from roads with 3000–8000 to >30,000 vehicles/day; open-habitat patch size;
area of quality microhabitat within a patch; adjacent land use; and distance to other open patches. Grassland bird presence
and regular breeding correlated significantly with both distance from road and habitat patch size. Distance to nearest other
open patch, irrespective of size, was not significant. Similarly, except for one species, adjacent land use, in this case
built area, was not significant. A light traffic volume of 3000–8000 vehicles/day (local collector street here) had no significant
effect on grassland bird distribution. For moderate traffic of 8000–15,000 (through street), there was no effect on bird presence
although regular breeding was reduced for 400 m from a road. For heavier traffic of 15,000–30,000 (two-lane highway), both
bird presence and breeding were decreased for 700 m. For a heavy traffic volume of ≥30,000 vehicles/day (multilane highway),
bird presence and breeding were reduced for 1200 m from a road. The results suggest that avian studies and long-term surveys
near busy roads may be strongly affected by traffic volume or changes in volume. We conclude that road ecology, especially
the effects extending outward >100 m from roads with traffic, is a sine qua non for effective land-use and transportation policy. 相似文献
998.
999.
1000.
资源型矿区可持续发展问题已成为人们关注的焦点.矿产资源需求的增加,开采力度的加强,资源不可避免的减少,而与矿产资源紧密相连的矿区,其生存和发展也随之面临着严峻挑战.从资源型矿区的现状出发,分析了我国矿区目前面临的问题,并从这些问题着手,提出了协调性的观点.基于协调性的观点,采用矿区可持续发展系统整体协调发展指数对资源型矿区可持续发展整体协调性进行了评价,认为资源型矿区的持续发展必须依靠其自身内部子系统的协调. 相似文献