全文获取类型
收费全文 | 40928篇 |
免费 | 374篇 |
国内免费 | 474篇 |
专业分类
安全科学 | 1011篇 |
废物处理 | 2212篇 |
环保管理 | 5015篇 |
综合类 | 6075篇 |
基础理论 | 11194篇 |
环境理论 | 19篇 |
污染及防治 | 9874篇 |
评价与监测 | 3106篇 |
社会与环境 | 3080篇 |
灾害及防治 | 190篇 |
出版年
2023年 | 145篇 |
2022年 | 334篇 |
2021年 | 329篇 |
2020年 | 253篇 |
2019年 | 299篇 |
2018年 | 1897篇 |
2017年 | 1864篇 |
2016年 | 1895篇 |
2015年 | 713篇 |
2014年 | 927篇 |
2013年 | 2490篇 |
2012年 | 1556篇 |
2011年 | 2797篇 |
2010年 | 1934篇 |
2009年 | 1827篇 |
2008年 | 2385篇 |
2007年 | 2727篇 |
2006年 | 1304篇 |
2005年 | 1207篇 |
2004年 | 1070篇 |
2003年 | 1214篇 |
2002年 | 1130篇 |
2001年 | 1279篇 |
2000年 | 903篇 |
1999年 | 551篇 |
1998年 | 377篇 |
1997年 | 362篇 |
1996年 | 366篇 |
1995年 | 435篇 |
1994年 | 464篇 |
1993年 | 366篇 |
1992年 | 380篇 |
1991年 | 358篇 |
1990年 | 400篇 |
1989年 | 350篇 |
1988年 | 304篇 |
1987年 | 283篇 |
1986年 | 224篇 |
1985年 | 252篇 |
1984年 | 286篇 |
1983年 | 270篇 |
1982年 | 244篇 |
1981年 | 225篇 |
1980年 | 180篇 |
1979年 | 198篇 |
1978年 | 180篇 |
1975年 | 142篇 |
1974年 | 121篇 |
1972年 | 132篇 |
1971年 | 131篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
901.
C.V. Srinivas R. Venkatesan V. Yesubabu C. Nagaraju K.M. Somayajai P. Chellapandi Baldev Raj 《Atmospheric environment (Oxford, England : 1994)》2010,44(24):2846-2864
A mesoscale atmospheric model PSU/NCAR MM5 is used to provide operational weather forecasts for a nuclear emergency response decision support system on the southeast coast of India. In this study the performance of the MM5 model with assimilation of conventional surface and upper-air observations along with satellite derived 2-d surface wind data from QuickSCAT sources is examined. Two numerical experiments with MM5 are conducted: one with static initialization using NCEP FNL data and second with dynamic initialization by assimilation of observations using four dimensional data assimilation (FDDA) analysis nudging for a pre-forecast period of 12 h. Dispersion simulations are conducted for a hypothetical source at Kalpakkam location with the HYSPLIT Lagrangian particle model using simulated wind field from the above experiments. The present paper brings out the differences in the atmospheric model predictions and the differences in dispersion model results from control and assimilation runs. An improvement is noted in the atmospheric fields from the assimilation experiment which has led to significant alteration in the trajectory positions, plume orientation and its distribution pattern. Sensitivity tests using different PBL and surface parameterizations indicated the simple first order closure schemes (Blackadar, MRF) coupled with the simple soil model have given better results for various atmospheric fields. The study illustrates the impact of the assimilation of the scatterometer wind and automated weather stations (AWS) observations on the meteorological model predictions and the dispersion results. 相似文献
902.
D. Martin C.S. Price I.R. White G. Nickless K.F. Petersson R.E. Britter A.G. Robins S.E. Belcher J.F. Barlow M. Neophytou S.J. Arnold A.S. Tomlin R.J. Smalley D.E. Shallcross 《Atmospheric environment (Oxford, England : 1994)》2010,44(25):3043-3052
As part of the DAPPLE programme two large scale urban tracer experiments using multiple simultaneous releases of cyclic perfluoroalkanes from fixed location point sources was performed. The receptor concentrations along with relevant meteorological parameters measured are compared with a three screening dispersion models in order to best predict the decay of pollution sources with respect to distance. It is shown here that the simple dispersion models tested here can provide a reasonable upper bound estimate of the maximum concentrations measured with an empirical model derived from field observations and wind tunnel studies providing the best estimate. An indoor receptor was also used to assess indoor concentrations and their pertinence to commonly used evacuation procedures. 相似文献
903.
Vishal Verma Martin M. Shafer James J. Schauer Constantinos Sioutas 《Atmospheric environment (Oxford, England : 1994)》2010,44(39):5165-5173
We assessed the contribution of water-soluble transition metals to the reactive oxygen species (ROS) activity of diesel exhaust particles (DEPs) from four heavy-duty vehicles in five retrofitted configurations (V-SCRT, Z-SCRT, DPX, hybrid, and school bus). A heavy-duty truck without any control device served as the baseline vehicle. Particles were collected from all vehicle-configurations on a chassis dynamometer under three driving conditions: cruise (80 km h?1), transient UDDS, and idle. A sensitive macrophage-based in vitro assay was used to determine the ROS activity of collected particles. The contribution of water-soluble transition metals in the measured activity was quantified by their removal using a Chelex® complexation method. The study demonstrates that despite an increase in the intrinsic ROS activity (per mass basis) of exhaust PM with use of most control technologies, the overall ROS activity (expressed per km or per h) was substantially reduced for retrofitted configurations compared to the baseline vehicle. Chelex treatment of DEPs water extracts removed a substantial (≥70%) and fairly consistent fraction of the ROS activity, which ascertains the dominant role of water-soluble metals in PM-induced cellular oxidative stress. However, relatively lower removal of the activity in few vehicle-configurations (V-SCRT, DPX and school bus idle), despite a large aggregate metals removal, indicated that not all species were associated with the measured activity. A univariate regression analysis identified several transition metals (Fe, Cr, Co and Mn) as significantly correlated (R > 0.60; p < 0.05) with the ROS activity. Multivariate linear regression model incorporating Fe, Cr and Co explained 90% of variability in ROS levels, with Fe accounting for the highest (84%) fraction of the variance. 相似文献
904.
The associations of 8 pesticides and pesticide metabolites with total diabetes (diagnosed and undiagnosed) and pre-diabetes (glycohemoglobin 5.7–6.4%) were evaluated using the National Health and Nutrition Examination Survey (NHANES), 1999–2004. Six of the pesticides were found to be associated with total diabetes in separate adjusted logistic regressions. These pesticides and pesticide metabolites were beta-hexachlorocyclohexane, p,p′-DDE, p,p′-DDT, oxychlordane, trans-nonachlor, and heptachlor epoxide. When the number of compounds elevated was tested, 4 or more, of the 6, elevated had an odds ratio of 4.99 (95% CI 1.97–12.61) compared to none elevated. When the 6 compounds were tested together in a single combined adjusted logistic regression only oxychlordane, a metabolite of chlordane, and heptachlor epoxide, a metabolite of heptachlor, were significantly associated with total diabetes. In the combined adjusted logistic regression, oxychlordane ≥ 14.5 ng/g lipid adjusted had an odds ratios of 1.90 (95% CI 1.09–3.32) compared to oxychlordane < 14.5 ng/g lipid adjusted, and heptachlor epoxide ≥ 14.6 ng/g lipid adjusted had an odds ratio of 1.70 (95% CI 1.16–2.49) compared to heptachlor epoxide < 14.6 ng/g lipid adjusted. Heptachlor epoxide and p,p′-DDT were significantly associated with pre-diabetes in separate adjusted logistic regressions. When these 2 compounds were tested together only heptachlor epoxide remained significantly associated with pre-diabetes. The evidence supporting the relationship between pesticides and pesticide metabolites, with diabetes, was strongest for heptachlor epoxide and oxychlordane, intermediate for p,p′-DDT, and least for beta-hexachlorocyclohexane, p,p′-DDE, and trans-nonachlor. Mirex and dieldrin were not associated with total diabetes or pre-diabetes. 相似文献
905.
The current trend in foreign aid is toward small-scale sustainable development projects in partnership with defined communities.
However, these projects are subject to the influences of self-interested human behavior, poorly defined community structures
and resources and organizational constraints that can prevent full realization of development models. Under these constraints,
attempting participatory community development models to the exclusion of other techniques may not be the most effective way
to achieve positive change. Instead, development agencies should consider adopting other proven elements of development in
combination with the spirit of community development to achieve a positive impact within the community and organizational
structures and ensure accountability for success. A small-scale attempted, sustainable development case study in Rwanda is
reviewed, as well as a new concept for larger scale development integrating ‘carbon credits’. Additionally, a development
accreditation organization is proposed to ensure additional accountability in this field. 相似文献
906.
Alexandros Flamos 《Environment, Development and Sustainability》2010,12(1):89-102
The (usually not professed) truth is that we are not destroying the planet due to lack of technology, but due to lack of application
of technology. Indeed, opportunities exist for renewable energy technologies’ diffusion under the new climate change regime
as they contribute to global sustainability through GHG mitigation and, they conform to national priorities by leading to
the enhancement of local economic activity, capacities and infrastructure. The clean development mechanism (CDM), although
is considered one of the global policy tools to contribute to sustainable development and technology transfer, has recently
been criticised for its unequal distribution of projects across countries and for insufficiently being embedded in developing
countries’ national energy context. In the above framework, this article presents the ENTTRANS approach, five indicative renewable
energy technologies, and insights about a more effective application of CDM, which may be part of the international process
striving towards sustainable development. 相似文献
907.
Exporting natural capital: the foreign eco-footprint on Costa Rica and implications for sustainability 总被引:1,自引:0,他引:1
As the world economy ‘globalizes’, trade has become a major mechanism by which much of the human population supports its needs.
While trade in resource commodities (natural income) can increase the well-being of people in both exporting and importing
countries, it can also lead to depletion of natural capital and the loss of ecosystems integrity. In recent years, various
researchers have attempted to address this problem using a consumption-based perspective on ecological change. Their work
shows that the loss of ecosystem integrity in almost any region of the world can be attributed to both local and international
consumer demand. This paper illustrates the utility of modified eco-footprint analysis in assessing export-related ecological
change in Costa Rica. We quantify ecological footprint of consumers around the world on the productive ecosystems of Costa
Rica, document the changing character of this footprint and highlight some of the linkages between production for export in
Costa Rica and ecological degradation. We then discuss the implications of the increasing trade-based entanglement of nations
for ecosystems and global sustainability. 相似文献
908.
Z. G. Prishutova 《Russian Journal of Ecology》2010,41(1):55-59
Vegetation was considerably trampled throughout Vodnyi Island in the Rostovskii Nature Reserve in 2007 because of a high pasture
load due to feral horses (0.15 horses/ha). Calculation of the food resources on the island, with its protection as part of
a nature reserve taken into account, has shown that the herd size is 3.5 times larger than the maximum allowable value. 相似文献
909.
Using the long-tailed tit (Aegithalos c. caudatus) as an example of the so-called irruptive species, the ecophysiological characteristics (body mass, fat reserves) and migration
speed during autumn period were analyzed. The mean body mass and the median fat score did not depend on the number of migrating
individuals. There was no evidence of the so-called stress in birds, participating in migration: migrants had even higher
fat reserves than residents, while no significant difference in the body mass was recorded. The increase in fat reserves in
the long-tailed tit during migration period was similar to the seasonal changes in energy reserves known for typical migrants.
This makes it possible for late-migrating individuals to maintain higher total speed of migration compared to early-migrating
ones. Basing on the obtained data, we conclude that the ecophysiological characteristics of the long-tailed tits migrating
in autumn are similar to those of regular migrants. 相似文献
910.
A set of criteria allowing demarcation between algocenoses is proposed. These criteria characterize the species composition,
group of dominants, and taxonomic and ecological structure of algocenoses. 相似文献