全文获取类型
收费全文 | 17531篇 |
免费 | 294篇 |
国内免费 | 398篇 |
专业分类
安全科学 | 619篇 |
废物处理 | 740篇 |
环保管理 | 2594篇 |
综合类 | 2992篇 |
基础理论 | 4496篇 |
环境理论 | 7篇 |
污染及防治 | 4629篇 |
评价与监测 | 994篇 |
社会与环境 | 1019篇 |
灾害及防治 | 133篇 |
出版年
2023年 | 97篇 |
2022年 | 177篇 |
2021年 | 173篇 |
2020年 | 192篇 |
2019年 | 154篇 |
2018年 | 287篇 |
2017年 | 270篇 |
2016年 | 420篇 |
2015年 | 336篇 |
2014年 | 448篇 |
2013年 | 1415篇 |
2012年 | 621篇 |
2011年 | 889篇 |
2010年 | 674篇 |
2009年 | 765篇 |
2008年 | 824篇 |
2007年 | 868篇 |
2006年 | 720篇 |
2005年 | 605篇 |
2004年 | 623篇 |
2003年 | 564篇 |
2002年 | 537篇 |
2001年 | 643篇 |
2000年 | 519篇 |
1999年 | 315篇 |
1998年 | 209篇 |
1997年 | 230篇 |
1996年 | 222篇 |
1995年 | 268篇 |
1994年 | 210篇 |
1993年 | 208篇 |
1992年 | 174篇 |
1991年 | 182篇 |
1990年 | 178篇 |
1989年 | 180篇 |
1988年 | 153篇 |
1987年 | 133篇 |
1986年 | 156篇 |
1985年 | 143篇 |
1984年 | 190篇 |
1983年 | 147篇 |
1982年 | 171篇 |
1981年 | 157篇 |
1980年 | 130篇 |
1979年 | 149篇 |
1978年 | 94篇 |
1977年 | 98篇 |
1975年 | 88篇 |
1974年 | 93篇 |
1972年 | 96篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
This article examines the Sarawak Corridor of Renewable Energy in Malaysia, or SCORE, a US $105 billion infrastructure development plan in Sarawak on the island of Borneo, from a sustainability standpoint. SCORE aims to build 20,000 megawatts of hydroelectric dams along a 320 km corridor comprising more than 70,000 km2 by 2030. The article begins by explaining social science methods utilized for its research interviews and site visits. It then argues that sustainability consists of seven principles articulated in international law: prudence, equity, responsibility, precaution, justice, governance, and compatibility. Next, the paper introduces readers to SCORE before assessing it according to these seven sustainability criteria. The paper finds that SCORE erodes environmental prudence by emitting millions of tons of carbon dioxide and feeding industries that will pollute the land and water. It worsens intergenerational equity by exacerbating poverty and consolidating wealth for corporations and politicians. It degrades responsibility by intensifying tropical deforestation and flaunts precaution by downplaying and ignoring risks to water quality and availability. It is unjust, imposing dams on communities and forcibly relocating thousands of indigenous people, mitigates good governance by condoning bribes and kickbacks along with the violent suppression of dissent, and is incompatible with Malaysia’s own energy policy targets and international standards. 相似文献
152.
We performed batch sorption experiments for 17beta-estradiol (E2) and 17alpha-ethynylestradiol (EE2) on selected soils collected from dairy farming regions of New Zealand. Isotherms were constructed by measuring the liquid phase concentration and extracting the solid phase with dichloromethane, followed by an exchange step, and analysis by HPLC and UV detection. The corresponding metabolite estrone, (E1) formed during equilibration of E2 with soil was taken into account to estimate the total percentage recoveries for the compounds, which ranged from 47-105% (E2 and E1) and 83-102% (EE2). Measured isotherms were linear, although some deviation from linearity was observed in a few soils, which was attributed to the finer textured particles and/or the allophanic nature of the soils having high surface area. There was a marked difference in K(d)(eff) (effective distribution coefficient) values for E2 and EE2 among the soils, consistent with the soils organic carbon content and ranged from 14-170 L kg(-1) (E2), and 12-40 L kg(-1) (EE2) in the soils common for both compounds. The sorption affinity of hormones in the soils followed an order: EE2相似文献
153.
Vertical distributions of (60)Co are determined in soil cores obtained from a 10-ha grassland, where anaerobically digested sludge was applied by surface spraying from 1986 to 1995 on the U.S. Department of Energy's Oak Ridge Reservation. These results, along with historical application records, are used to estimate vertical-migration rates and perform a mass balance. The presence of (60)Co results solely from the sludge-application process. Soil, vegetation, and surface-water samples were collected. Eleven soil cores were sectioned into 3-cm increments and analyzed by gamma-ray spectrometry. No (60)Co was detected in the vegetation or water samples. The downward migration rate of (60)Co in the upper 15cm of soil ranged from 0.50 to 0.73cm/yr. About 98%, 0.020+/-0.011Bq/cm(2), of (60)Co remained in the upper 15cm of soil, which compared favorably with the expected (60)Co activity based on historical records of 0.019+/-0.010Bq/cm(2). 相似文献
154.
Vichot L Boyer C Boissieux T Losset Y Pierrat D 《Journal of environmental radioactivity》2008,99(10):1636-1643
In order to quantify tritium impact on the environmental, we studied vegetation continuously exposed to a tritiated atmosphere. We chose lichens as bio-indicators, trees for determination of past tritium releases of the Valduc Centre, and lettuce as edible vegetables for dose calculation regarding neighbourhood. The Pasquill and Doury models from the literature were tested to estimate tritium concentration in the air around vegetable for distance from the release point less than 500m. The results in tree rings show that organically bound tritium (OBT) concentration was strongly correlated with tritium releases. Using the GASCON model, the modelled variation of OBT concentration with distance was correlated with the measurements. Although lichens are recognized as bio-indicators, our experiments show that they were not convenient for environmental surveys because their age is not definitive. Thus, tritium integration time cannot be precisely determined. Furthermore, their biological metabolism is not well known and tritium concentration appears to be largely dependent on species. An average conversion rate of HTO to OBT was determined for lettuce of about 0.20-0.24%h(-1). Nevertheless, even if it is equivalent to values already published in the literature for other vegetation, we have shown that this conversion rate, established by weekly samples, varies by a factor of 10 during the different stages of lettuce development, and that its variation is linked to the biomass derivative. 相似文献
155.
Studies on paleosols under an archaeological landmark of a rare type (a complex of kurgans with “whiskers”) dating from the Early Iron Age (the fourth century AD) have been performed in the steppe zone of the Transural Plateau. The size and shape of third-order soil polygons under stony ridges (“whiskers”) between the kurgans have been described in detail. The results have shown that the paleosol under the kurgans erected at the turn of the Late Sarmatian and Hun times (1600 years ago) is characterized by a higher humus content and deeper location of the carbonate horizon, compared to the recent soil. This indicates that an increase in atmospheric humidity took place in the fourth century AD. 相似文献
156.
Michael A. Smith Ingvar L. Larsen Audeen W. Fentiman 《Journal of environmental radioactivity》2008,99(10):1611
Vertical distributions of 60Co are determined in soil cores obtained from a 10-ha grassland, where anaerobically digested sludge was applied by surface spraying from 1986 to 1995 on the U.S. Department of Energy's Oak Ridge Reservation. These results, along with historical application records, are used to estimate vertical-migration rates and perform a mass balance. The presence of 60Co results solely from the sludge-application process. Soil, vegetation, and surface-water samples were collected. Eleven soil cores were sectioned into 3-cm increments and analyzed by gamma-ray spectrometry. No 60Co was detected in the vegetation or water samples. The downward migration rate of 60Co in the upper 15 cm of soil ranged from 0.50 to 0.73 cm/yr. About 98%, 0.020 ± 0.011 Bq/cm2, of 60Co remained in the upper 15 cm of soil, which compared favorably with the expected 60Co activity based on historical records of 0.019 ± 0.010 Bq/cm2. 相似文献
157.
A kinetic-allometric approach to predicting tissue radionuclide concentrations for biota 总被引:2,自引:0,他引:2
Allometry, or the biology of scaling, is the study of size and its consequences. It has become a useful tool for comparative physiology. There are several allometric equations that relate body size to many parameters, including ingestion rate, lifespan, inhalation rate, home range and more. While these equations were originally derived from empirical observations, there is a growing body of evidence that these relationships have their origins in the dynamics of energy transport mechanisms. As part of an ongoing effort by the Department of Energy in developing generic methods for evaluating radiation dose to biota, we have examined the utility of applying allometric techniques to predicting radionuclide tissue concentration across a large range of terrestrial and riparian species of animals. This particular study examined 23 radionuclides. Initial investigations suggest that the allometric approach can provide a useful tool to derive limiting values of uptake and elimination factors for animals. 相似文献
158.
Seaman NL 《Environment international》2003,29(2-3):245-252
Meteorology is one of the major factors contributing to air-pollution episodes. More accurate representation of meteorological fields has been possible in recent years through the use of remote sensing systems, high-speed computers and fine-mesh meteorological models. Over the next 5-20 years, better meteorological inputs for air quality studies will depend on making better use of a wealth of new remotely sensed observations in more advanced data assimilation systems. However, for fine mesh models to be successful, parameterizations used to represent physical processes must be redesigned to be more precise and better adapted for the scales at which they will be applied. Candidates for significant overhaul include schemes to represent turbulence, deep convection, shallow clouds, and land-surface processes. Improvements in the meteorological observing systems, data assimilation and modeling, coupled with advancements in air-chemistry modeling, will soon lead to operational forecasting of air quality in the US. Predictive capabilities can be expected to grow rapidly over the next decade. This will open the way for a number of valuable new services and strategies, including better warnings of unhealthy atmospheric conditions, event-dependent emissions restrictions, and now casting support for homeland security in the event of toxic releases into the atmosphere. 相似文献
159.
Ketterer ME Hafer KM Link CL Royden CS Hartsock WJ 《Journal of environmental radioactivity》2003,67(3):191-206
236U (t(1/2)=2.3 x 10(7) y) is formed as a result of thermal neutron capture by (235)U. In naturally occurring U ores, where a high neutron flux is present from spontaneous fission of (238)U, (236)U/(238)U atom ratios are approximately 10(-4) ppm. In the natural Earth's crust, unaffected by nuclear fallout, these ratios are expected to be on the order of 10(-8) ppm. Reactor-irradiated U, however, exhibits high (236)U/(238)U atom ratios approaching 10(4) ppm. As a result, the presence of very small quantities of reactor-irradiated U will significantly enhance the "background" (236)U/(238)U atom ratio. When sufficiently elevated (236)U/(238)U ratios are present, the determination of (236)U/(238)U by rapid inductively coupled plasma mass spectrometric (ICPMS) methods is attractive. We have used sector ICPMS at medium resolving power (R=3440) to measure (236)U/(238)U atom ratios with a determination limit of 0.2 ppm. The limiting factors in the measurement are the (235)U(1)H(+) isobar and background signal at m/z 236 arising from the (238)U(+) peak tail. Based upon the analysis of replicates and considerations of possible systematic errors, uncertainties of +/-5% are found for (236)U/(238)U atom ratios of 1-100 ppm. This procedure has been demonstrated in studies of anthropogenic (236)U in the environment at three locations: (a) offsite soils from the vicinity of the Rocky Flats Environmental Technology site (Golden, Colorado, USA); (b) sediments from the Ashtabula River (Ohio, USA); and (c) sediments from the Mersey estuary (Liverpool, UK). In each of these three locations, definite plumes of elevated (236)U/(238)U are identified and characterized. Maximum (236)U/(238)U atom ratios observed in RFETS-vicinity soils, the Ashtabula River, and the Mersey Estuary are 2.8, 140, and 4.4 ppm, respectively. 相似文献
160.