全文获取类型
收费全文 | 16438篇 |
免费 | 172篇 |
国内免费 | 137篇 |
专业分类
安全科学 | 450篇 |
废物处理 | 632篇 |
环保管理 | 2308篇 |
综合类 | 2577篇 |
基础理论 | 4487篇 |
环境理论 | 4篇 |
污染及防治 | 4318篇 |
评价与监测 | 1011篇 |
社会与环境 | 855篇 |
灾害及防治 | 105篇 |
出版年
2022年 | 111篇 |
2021年 | 130篇 |
2020年 | 106篇 |
2019年 | 149篇 |
2018年 | 225篇 |
2017年 | 223篇 |
2016年 | 355篇 |
2015年 | 240篇 |
2014年 | 361篇 |
2013年 | 1273篇 |
2012年 | 446篇 |
2011年 | 639篇 |
2010年 | 539篇 |
2009年 | 520篇 |
2008年 | 693篇 |
2007年 | 695篇 |
2006年 | 663篇 |
2005年 | 509篇 |
2004年 | 594篇 |
2003年 | 527篇 |
2002年 | 486篇 |
2001年 | 704篇 |
2000年 | 474篇 |
1999年 | 284篇 |
1998年 | 241篇 |
1997年 | 217篇 |
1996年 | 228篇 |
1995年 | 249篇 |
1994年 | 272篇 |
1993年 | 222篇 |
1992年 | 248篇 |
1991年 | 222篇 |
1990年 | 255篇 |
1989年 | 240篇 |
1988年 | 195篇 |
1987年 | 174篇 |
1986年 | 158篇 |
1985年 | 168篇 |
1984年 | 193篇 |
1983年 | 182篇 |
1982年 | 186篇 |
1981年 | 182篇 |
1980年 | 138篇 |
1979年 | 153篇 |
1978年 | 131篇 |
1977年 | 117篇 |
1975年 | 118篇 |
1974年 | 115篇 |
1973年 | 110篇 |
1972年 | 133篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
141.
Joshua W. Faulkner Zachary M. Easton Wei Zhang Larry D. Geohring Tammo S. Steenhuis 《Journal of environmental management》2010,91(8):1794-1801
Vegetative treatment areas (VTAs) are commonly being used as an alternative method of agricultural process wastewater treatment. However, it is also apparent that to completely prevent discharge of pollutants to the surrounding environment, settling of particulates and bound constituents from overland flow through VTAs is not sufficient. For effective remediation of dissolved agricultural pollutants, VTAs must infiltrate incoming wastewater. A simple water balance model for predicting VTA soil saturation and surface discharge in landscapes characterized by sloping terrain and a shallow restrictive layer is presented and discussed. The model accounts for the cumulative effect of successive rainfall events and wastewater input on soil moisture status and depth to water table. Nash–Sutcliffe efficiencies ranged from 0.65 to 0.81 for modeled and observed water table elevations after calibration of saturated hydraulic conductivity. Precipitation data from relatively low, average, and high annual rainfall years were used with soil, site, and contributing area data from an example VTA for simulations and comparisons. Model sensitivity to VTA width and contributing area (i.e. barnyard, feedlot, silage bunker, etc.) curve number was also investigated. Results of this analysis indicate that VTAs should be located on steeper slopes with deeper, more-permeable soils, which effectively lowers the shallow water table. In sloping landscapes (>2%), this model provides practitioners an easy-to-use VTA design and/or risk assessment tool that is more hydrological process-based than current methods. 相似文献
142.
Pamela D. McElwee 《Environmental management》2010,45(1):113-131
This article examines the use of forests in a protected area by nearby agriculturalists in central Vietnam. Research indicates
that the majority of rural farmers interviewed who lived near a state designated protected area were receiving both subsistence
and cash incomes from forest-based activities, primarily from the collection of forest products. However, much of the collection
of forest produce was officially illegal, as it occurred in state protected forests, and interdiction efforts were on the
increase. Yet, little attention has been paid in Vietnam to the need for income substitution for households who lose access
to forest produce as a result of conservation enforcement, particularly in the case of farmers who live near, but not in,
protected areas; their resources use has been ‘invisible’ due to a lack of attention and research on the topic. This misunderstanding
of the importance of forests to rural farmers has the potential to result in households facing adverse welfare and livelihood
outcomes as protected areas boundaries are tightened, and local communities face increased opportunity costs due to stricter
conservation enforcement. The article concludes that substitution for loss of income due to conservation activities would
best be achieved through carefully targeted interventions to specific high-impact and high-dependency households. Additionally,
investments in new sources of wage labor and other low capital-input activities, rather than in agriculture, would likely
be of most benefit. 相似文献
143.
We examined the vertical distributions of scallop (Placopecten magellanicus) veligers in deep (0.6 m diameter, 9.5 m deep) polyethylene mesocosms from December 1991 to January 1992. In the mesocosms
temperature stratification varied from 0 to 1.5 °C. Profiles of vertical distribution revealed several repeated patterns.
Peaks in veliger numbers often appeared at the water surface and just above the thermocline. Higher density patches were seen
below the surface peaks, and revealed the presence of bio-convective cells. Distribution away from these discontinuities was
usually even. Distribution of veligers was affected by thermoclines above 1.0 °C. Responses to thermoclines varied with larval
age and time of day, and 28 to 30 d veligers passed in both directions through a 1.5 °C thermocline. We conclude that larval
behaviour is a major determinant of whether veligers pass through a thermocline. Kinematic viscosity may play a role in perception
of temperature changes. Two potential consequences of such behaviour are (1) remaining in more productive upper water layers,
where feeding opportunities are enhanced, and (2) increased horizontal transport in the region of the thermocline, which may
enhance recruitment.
Received: 15 May 1996 / Accepted: 11 May 2000 相似文献
144.
Y. Nassiri P. S. Rainbow C. Amiard-Triquet F. Rainglet B. D. Smith 《Marine Biology》2000,136(3):477-484
The talitrid amphipod crustacean Orchestia gammarellus (Pallas) was collected from metal-contaminated (Dulas Bay, Gironde) and control (Millport) sites in the UK and France. Irrespective
of site of origin, the amphipods showed the same physiological mechanism of trace-metal detoxification, involving the ventral
caeca. Copper was always present in lysosomal residual bodies in the ventral caeca. Following laboratory exposure to zinc
and cadmium, the lysosomes usually contained both copper and zinc but cadmium was not detectable. The lysosomal copper concentration
is positively correlated to that of sulphur, while the concentration of lysosomal zinc is related to that of phosphorus. Results
are interpreted in terms of the differential rates of turnover of metallothioneins chelating copper, zinc or cadmium.
Received: 9 February 1999 / Accepted: 2 December 1999 相似文献
145.
Effects of Land-Cover Changes on Mammals in a Neotropical Region: a Modeling Approach 总被引:3,自引:0,他引:3
Alfredo D. Cuarón 《Conservation biology》2000,14(6):1676-1692
146.
Testes mass in megachiropteran bats varies in accordance with sperm competition theory 总被引:4,自引:0,他引:4
D. J. Hosken 《Behavioral ecology and sociobiology》1998,44(3):169-177
Sperm competition is a widespread phenomenon influencing a range of characters, including investment in gonadal tissue. Conspecific
proximity is one factor which can influence the risk of sperm competition and hence testicular investment, and decreased confidence
of paternity may be one cost of group living. Aspects of female biology may also influence spermatogenic investment and sperm
morphology. This study examines the associations between relative testes mass and roost-group size across 17 species of Megachiroptera.
Associations between breeding season duration and investment in spermatogenesis are also examined, as are associations between
female reproductive tract dimensions and testes mass and dimensions of spermatozoa across all bats. Relative testes mass was
significantly positively associated with roost-group size at a species level and after appropriate phylogenetic control (pairwise
comparisons and comparison of independent contrasts). There were no significant relationships between breeding season duration
and relative testes mass. Across all bats, neither testes mass nor sperm length were significantly related to dimensions of
the female tract. The results are discussed in the context of sperm competition.
Received: 7 January 1998 / Accepted after revision: 8 August 1998 相似文献
147.
Genetic divergence and phylogenetic inferences in five species of Mugilidae (Pisces: Perciformes) 总被引:4,自引:0,他引:4
Allozyme electrophoresis was used to compare the genetic divergence of global populations of Mugil cephalus Linnaeus, 1758 and two congeneric [M.␣curema Cuvier & Valenciennes, 1836; M. gyrans (Jordan & Gilbert, 1885)] and two more distantly related [Liza ramada (Risso, 1826); Xenomugil thoburni (Jordan & Starks, 1896)] species on the basis of 18 enzyme loci. The amount of genetic divergence among the species examined
is in agreement with their present systematic status, the differences being larger among non-congeneric species than among
species of the same genus. Intraspecific genetic distances in M. cephalus (average Nei's D= 0.154), although higher than those reported for conspecific populations of fish, appear to be small when compared to the
interspecific values among mugilid species (0.821 ≤ Nei's D ≤ 1.744). Phylogenetic trees obtained by genetic distance methods and discrete character parsimony analysis were of similar
topology, except for the relationships within the genus Mugil and for the arrangement of M. cephalus populations.
Received: 7 April 1997 / Accepted: 4 February 1998 相似文献
148.
149.
150.