全文获取类型
收费全文 | 457篇 |
免费 | 7篇 |
国内免费 | 4篇 |
专业分类
安全科学 | 23篇 |
废物处理 | 15篇 |
环保管理 | 89篇 |
综合类 | 76篇 |
基础理论 | 78篇 |
污染及防治 | 136篇 |
评价与监测 | 27篇 |
社会与环境 | 14篇 |
灾害及防治 | 10篇 |
出版年
2023年 | 4篇 |
2022年 | 10篇 |
2021年 | 3篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2017年 | 13篇 |
2016年 | 9篇 |
2015年 | 6篇 |
2014年 | 9篇 |
2013年 | 48篇 |
2012年 | 13篇 |
2011年 | 26篇 |
2010年 | 12篇 |
2009年 | 7篇 |
2008年 | 24篇 |
2007年 | 21篇 |
2006年 | 26篇 |
2005年 | 25篇 |
2004年 | 15篇 |
2003年 | 17篇 |
2002年 | 18篇 |
2001年 | 8篇 |
1999年 | 4篇 |
1997年 | 9篇 |
1996年 | 6篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1975年 | 6篇 |
1971年 | 2篇 |
1969年 | 4篇 |
1967年 | 2篇 |
1964年 | 5篇 |
1962年 | 2篇 |
1961年 | 2篇 |
排序方式: 共有468条查询结果,搜索用时 15 毫秒
421.
Judith Bush Peter Phillimore Tanja Pless-Mulloli Christine Thompson 《Local Environment》2005,10(6):649-664
This paper examines controversy during the 2001 foot-and-mouth outbreak after mass carcass burial sites were selected at two sites in northeast England, and focuses on shortcomings in public consultation surrounding the carcass disposal policy. The slaughter of six million animals necessitated a national disposal strategy on a hitherto unknown scale. The belated decision to concentrate carcass disposal in a small number of mass burial sites provoked more opposition in the two ex-mining localities selected in the northeast than anywhere else. In both cases local liaison committees were established to manage dialogue between residents and public authorities. We argue that, although seen by the authorities primarily as a vehicle for risk communication and public reassurance, for residents these functioned chiefly as a vehicle for holding public authorities to account. These divergent purposes were overshadowed by the chaotic circumstances in which the early stages of the mass burial policy were implemented, and the way in which the carcass disposal policy was dictated by the operation of the slaughter policy, whose draconian form precluded any but the most cursory public consultation. 相似文献
422.
Formula allocation is a major tool for the distribution of public funds in the United States of America. This paper explores several examples of formulae used in U.S. domestic programmes, looking at their construction, meaning and consequences. The authors argue that the design of formulae is both a political and technical task. The paper concludes with a series of recommendations to improve formulae as tools of distributional policy. 相似文献
423.
Kennith E. Foster Martin M. Karpiscak Richard G. Brittain 《Journal of the American Water Resources Association》1988,24(6):1201-1206
ABSTRACT: A typical single family residence in Tucson, Arizona, was retrofitted to incorporate low-water-use fixtures and water reuse systems. The use of municipal water was reduced by 53 percent to 53 gallons per capita per day (gpcd) and total water use at the home was reduced by 33 percent to 74 gpcd. 相似文献
424.
Topographic Controls of Nitrogen,Sulfur, and Carbon Transport from a Tolerant Hardwood Hillslope 总被引:2,自引:0,他引:2
The lateral down-slope movement of water, NO3
-, NH4
+, SO4
2-, H+ and DOC through an ablation till was examined from 1987 to 1990 for a one hectaresoil catena on a steep hillslope with uniform forest cover at the Turkey Lakes Watershed (TLW), Ontario, Canada. Natural variation in the export of nutrients from the soil profile via soil water to Little Turkey Lake was assessed in relation to nutrient distribution in soil at different topographic positions.Subsurface throughflow exhibited dramatic differences in nutrientconcentrations and fluxes with slope position, largely reflectingthat of the soil horizons through which the water passed. GreaterNO3
-, SO4
2-, and DOC concentrations in subsurface water in the upper, well-drained hillslope were a reflection of enrichment by contact with more acidic, more developed podzols, and more favorable soil physical and biological conditions for NO3
- retention in solution.Nutrient inputs to the lake were strongly influenced by increaseddown-slope transport of water, and increased SO4
2-, N, and C retention in wetter, less-developed podzolic soils that characterize lower slope positions. An understanding of water movement and soil development variation withtopographic position was required to accurately estimate nutrient budgets for steep slopes at TLW. 相似文献
425.
Korb J 《Die Naturwissenschaften》2005,92(1):45-49
Social insect colonies are not the harmonious entities they were once considered. Considerable conflicts exist between colony members, as has been shown for Hymenoptera. For termites, similar studies are lacking, but aggressive manipulations have been claimed to regulate sexual development, and even to account for the evolution of workers. This study on a basal termite, Cryptotermes secundus (Kalotermitidae), suggests that the importance of aggressive manipulations in termites has been overemphasized. Wing-bud mutilations, a means proposed to regulate the development of dispersing sexuals (alates), seem to be artifacts of handling conditions that cause disturbance. Aggressive behaviors never occurred unless colonies were disturbed. Theoretical considerations further showed that the potential for intense conflict among termite nestmates is low compared to hymenopteran societies. Strong conflicts are only expected to occur over the replacement of natal reproductives that died, while less intense conflicts should exist over the development into alates when food in the colony becomes limiting. Accordingly, intracolonial aggressive interactions over replacement are common, whereas nestmates seem to manipulate alate development via proctodeal feeding when food resources decline. However, the latter is rather an honest signal than a manipulation because only the most competent prospective dispersers can impede the development of nestmates. 相似文献
426.
427.
Korb J 《Die Naturwissenschaften》2003,90(5):212-219
Some of the most sophisticated of all animal-built structures are the mounds of African termites of the subfamily Macrotermitinae, the fungus-growing termites. They have long been studied as fascinating textbook examples of thermoregulation or ventilation of animal buildings. However, little research has been designed to provide critical tests of these paradigms, derived from a very small number of original papers. Here I review results from recent studies on Macrotermes bellicosus that considered the interdependence of ambient temperature, thermoregulation, ventilation and mound architecture, and that question some of the fundamental paradigms of termite mounds. M. bellicosus achieves thermal homeostasis within the mound, but ambient temperature has an influence too. In colonies in comparably cool habitats, mound architecture is adapted to reduce the loss of metabolically produced heat to the environment. While this has no negative consequences in small colonies, it produces a trade-off with gas exchange in large colonies, resulting in suboptimally low nest temperatures and increased CO2 concentrations. Along with the alteration in mound architecture, the gas exchange/ventilation mechanism also changes. While mounds in the thermally appropriate savannah have a very efficient circular ventilation during the day, the ventilation in the cooler forest is a less efficient upward movement of air, with gas exchange restricted by reduced surface exchange area. These results, together with other recent findings, question entrenched ideas such as the thermosiphon-ventilation mechanism or the assumption that mounds function to dissipate internally produced heat. Models trying to explain the proximate mechanisms of mound building, or building elements, are discussed. 相似文献
428.
We examined the distribution and abundance of organisms on subtidal rocky reefs at nine sites around the Chatham Islands, a remote group 780 km east of southern New Zealand. We sampled five depth strata ranging from 1 to<16 m to identify spatial patterns in the abundance of algae and invertebrates and to assess their variation within and among sites. This information is used to discuss hypotheses concerning community structure at this remote locality. Several patterns were apparent. The immediate subtidal was occupied by the southern bull kelp Durvillaea spp. A suite of 11 fucalean species were dominant to a depth of 10 m with an average abundance of 28 m-2, while one species, Carpophyllum flexuosum, occurred mostly in deeper water. Only two laminarian species of algae were present at the islands. The indigenous Lessonia tholiformis was abundant at 2.5 to 15 m and was not found in deeper water, while the giant kelp Macrocystis pyrifera was abundant at two sites in 12 to 18 m. The commercially valuable abalone Haliotis iris was extremely abundant in shallow water, with an overall mean of 6 m-2 at 5 m. The sea urchin Evechinus chloroticus was common, but reached high densities only in small (<25 m2) patches. The characteristic urchin-dominated zones reported in kelp beds world-wide were not seen. There was considerable site-to-site variation in the occurrence and abundance of individual species. Some differences between sites were associated with shelter from swell (e.g. M. pyrifera was found only in sheltered sites) and physical habitat (e.g. juvenile H. iris were found only beneath boulders inshore), but much of the variation could not be explained by physical or depth-related factors alone. We hypothesize that the differences in these kelp bed assemblages compared to mainland New Zealand are partially due to the high degree of endemism at the Chatham Islands. Local variation cannot be explained by herbivory, and is most likely the result of the various life-history characteristics of the major habitat-forming species, the large brown algae. 相似文献
429.
430.
A possible association of limb reduction defects with chorionic villus sampling (CVS) may be related to compromised umbilical blood flow from the trauma of the procedure. We hypothesized that because CVS may disrupt or compromise umbilical blood flow to the fetus, either by vasoconstriction, bradycardia, or emboli, we would detect these changes using Doppler velocimetry. A cohort of 21 consecutive consenting patients undergoing first-trimester elective CVS for prenatal diagnosis were entered into a prospective longitudinal study. Colour flow Doppler velocimetry was performed on fetal umbilical arterial blood flow immediately before and after CVS to measure the pulsatility index, fetal heart rate, per cent flow time, and maximum flow velocity. Measurements were obtained from three consecutive cardiac cycles in three different umbilical segments and averaged. Potentially confounding variables also recorded included gestational age, method of CVS, number of passes, number of aspirations, placental location, tissue sample size, and operator. Umbilical velocimetry values before and after CVS were compared using the paired t-test and showed no statistically significant differences. No differences were found when data were analysed by gestational age, sample size, method, number of aspirations, placental location, or operator. We were unable to detect any significant change in fetal umbilical arterial blood flow velocimetry or heart rate after performing CVS. Umbilical blood flow does not appear to be routinely compromised by CVS. 相似文献