全文获取类型
收费全文 | 238篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
安全科学 | 15篇 |
废物处理 | 2篇 |
环保管理 | 68篇 |
综合类 | 59篇 |
基础理论 | 48篇 |
污染及防治 | 51篇 |
评价与监测 | 5篇 |
社会与环境 | 4篇 |
灾害及防治 | 6篇 |
出版年
2023年 | 2篇 |
2021年 | 3篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2017年 | 9篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 7篇 |
2013年 | 16篇 |
2012年 | 9篇 |
2011年 | 9篇 |
2010年 | 10篇 |
2009年 | 11篇 |
2008年 | 10篇 |
2007年 | 10篇 |
2006年 | 10篇 |
2005年 | 5篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 5篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1996年 | 7篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 3篇 |
1972年 | 2篇 |
1963年 | 2篇 |
1961年 | 2篇 |
1960年 | 2篇 |
1946年 | 2篇 |
1937年 | 1篇 |
1936年 | 1篇 |
1932年 | 1篇 |
1926年 | 1篇 |
1922年 | 1篇 |
1919年 | 2篇 |
1913年 | 4篇 |
排序方式: 共有258条查询结果,搜索用时 15 毫秒
191.
192.
193.
194.
195.
Dr. Hans Arnold 《Die Naturwissenschaften》1913,1(36):862-865
196.
197.
Douglas J. McCauley Fiorenza Micheli Hillary S. Young Derek P. Tittensor Daniel R. Brumbaugh Elizabeth M. P. Madin Katherine E. Holmes Jennifer E. Smith Heike K. Lotze Paul A. DeSalles Suzanne N. Arnold Boris Worm 《Marine Biology》2010,157(12):2739-2750
Large animals are severely depleted in many ecosystems, yet we are only beginning to understand the ecological implications of their loss. To empirically measure the short-term effects of removing large animals from an ocean ecosystem, we used exclosures to remove large fish from a near-pristine coral reef at Palmyra Atoll, Central Pacific Ocean. We identified a range of effects that followed from the removal of these large fish. These effects were revealed within weeks of their removal. Removing large fish (1) altered the behavior of prey fish; (2) reduced rates of herbivory on certain species of reef algae; (3) had both direct positive (reduced mortality of coral recruits) and indirect negative (through reduced grazing pressure on competitive algae) impacts on recruiting corals; and (4) tended to decrease abundances of small mobile benthic invertebrates. Results of this kind help advance our understanding of the ecological importance of large animals in ecosystems. 相似文献
198.
Kate Arnold Yvonne Pohlner Klaus Zuberbühler 《Behavioral ecology and sociobiology》2008,62(4):549-559
Some non-human primates produce acoustically distinct alarm calls to different predators, such as eagles or leopards. Recipients
respond to these calls as if they have seen the actual predator, which has led to the notion of functionally referential alarm
calls. However, in a previous study with free-ranging putty-nosed monkeys (Cercopithecus nictitans martini), we demonstrated that callers produced two acoustically distinct alarm calls to eagle shrieks and leopard growls, but both
alarm calls were given to both predators. We can think of two basic explanations for this surprising result, a methodological
and theoretical one. Firstly, acoustic predator models may not always be suitable to test alarm call behaviour in primates,
sometimes causing uncharacteristic behaviour. Secondly, referential alarm calling may not be a universal feature of primate
alarm call systems. Considering the methodological and theoretical importance of these possibilities, we conducted a follow-up
study using life-sized leopard, eagle, and human models on the same population and compared the resulting vocal responses
to those given to acoustic predator models. We compared the alarm call series given to each of these predator model types
and found a considerable degree of consistency suggesting that the mode of presentation did not affect anti-predator calling
strategies. However, evidence for audience effects on calling behaviour was inconclusive. While it appears that predator class
is reliably encoded by different call series types irrespective of the mode of presentation, observations of these same call
series given in non-predatory contexts indicate that predator class is unlikely to be the relevant organising principle underlying
the alarm-calling behaviour in this species. We conclude by offering an alternative, non-referential, account of the alarm-calling
system exhibited by this species.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
199.
In classical theory, species are assumed to achieve dominance through competitive exclusion, but if food resources are limiting, cross-habitat trophic subsidies could also underpin dominance. The impact of dominant species on community dynamics may depend on the energy base of population size. We report on an unusual, spatially subsidized population of a tropical, stream-dwelling crab that dominates the benthic fauna of a Kenyan stream. Diet and stable isotope analyses indicated that this crab is a true omnivore, with terrestrial subsidies dominating both plant and animal resources. Unusually, the animal prey included almost no aquatic invertebrates. Instead, a single species of ant constituted approximately 35% of the annual diet (stomach contents analysis) and up to 90% of assimilated nitrogen (estimates from stable isotope analysis). Ants may be pivotal to enabling crab dominance, and this crab may be largely disconnected from the local trophic network for its dietary needs. The paucity of other invertebrates in the stream community suggests that this super-dominant crab is a strong interactor that suppresses aquatic invertebrate populations. Common stabilizing attributes of spatially subsidized food webs (e.g., asynchronous prey availability, wide feeding niche, consumer migration) were absent from this system, and although apparently stable, it may be vulnerable to disturbance in the donor habitat. 相似文献
200.
Richard B. Moore Kenneth Belitz Joseph Ayotte Terri L. Arnold Laura Hayes Jennifer B. Sharpe Jeffrey J. Starn 《Journal of the American Water Resources Association》2023,59(1):127-145
Two radioactive elements, uranium (U) and radon (Rn), which are of potential concern in New Hampshire (NH) groundwater, are investigated. Exceedance probability maps are tools to highlight locations where the concentrations of undesirable substances in the groundwater may be elevated. Two forms of statistical analysis are used to create exceedance probability maps for U and Rn in NH groundwater. The first, Boosted Regression Tree (BRT), was selected for estimating U exceedance values. It computes exceedance values directly using the Bernoulli distribution function. The second method of statistical analysis used for Rn to determine exceedance probabilities is ordinary least squares (OLS) regression. In the process of determining exceedance probabilities for U and Rn, the utility of a new dataset is investigated. That new predictor dataset is the Multi-Order Hydrologic Position (MOHP) dataset. MOHP raster datasets have been produced nationally for the conterminous United States at a 30-m resolution. The concept behind MOHP is that, for any given point on the earth's surface, there is the potential for a longer groundwater flow path as one goes deeper beneath the land surface. MOHP predictors were tested in both models. Three MOHP predictors were found useful in the BRT model and two in the OLS model. MOHP data were found useful as predictors along with other site characteristics in predicting U and Rn exceedance probabilities in New Hampshire groundwater. 相似文献