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Stefano Mazzoleni Giuliano Bonanomi Guido Incerti Max Rietkerk 《Ecological modelling》2010,221(23):2784-2792
Current theories may not fully explain why latitudinal patterns of plant diversity differ between terrestrial and flooded ecosystems. Moreover, the co-occurrence of hyper diverse stands in lowland tierra firma (not inundated) forests and almost monospecific stands in mangroves and gallery riparian vegetation within the tropics remains enigmatic. Building on evidence from ecology and agriculture, we present a new model investigating the hypothesis that, besides the general positive feedback of plant growth by nutrients release, litter decomposition builds up an intra-specific negative feedback functionally linked with tree diversity. The model results were compared with extensive published data sets both across and within latitudinal zones. The model predicts correctly the biomass production and decomposition process, as well as the number of tree species, their relative abundance in all environmental conditions providing a novel, putative explanation also for the diversity variations observed within the tropics. The model demonstrates a possible mechanistic link between the carbon cycle and biodiversity patterns, which is interesting in the debate about advancing in the direction of a unifying ecosystem theory. 相似文献
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Max Vercruyssen Eliazor Kamon Peter A Hancock 《International journal of occupational safety and ergonomics》2007,13(1):15-27
On separate days, 6 highly trained participants performed psychomotor tests while breathing for 60 min 3 carbon dioxide (CO(2)) mixtures (room air, 3% CO(2), or 4% CO(2)) prior to, between, and following two 15-min treadmill exercise bouts (70% VO(2)(max)). Each individual was extensively practiced (at least 4 days) before testing began, and both gas conditions and order of tasks were counterbalanced. Results showed physiological reactions and work-related psychomotor effects, but no effects of gas concentration on addition, multiplication, grammatical reasoning, or dynamic postural balance. These findings help define behavioral toxicity levels and support a re-evaluation of existing standards for the maximum allowable concentrations (also emergency and continuous exposure guidance levels) of CO(2). This research explored the selection of psychometric instruments of sufficient sensitivity and reliability to detect subtle changes in performance caused by exposure to low levels of environmental stress, in this case differential levels of CO(2) in the inspired air. 相似文献
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The study of the negotiation process has enjoyed a recent resurgence of scholarly interest. Of particular concern is the ability of negotiators to achieve solutions which result in integrative outcomes. The purpose of this study is to identify the effects of different levels of aspiration/goals on negotiator success and their ability to reach integrative solutions in a competitive market. One hundred fifty-eight subjects who were assigned one of four levels of goal difficulty-no goal, compromise goal, challenging goal, and difficult goal-participated in a competitive, multi-person, multi-transaction market simulation. The study found (1) challenging and difficult goals significantly enhanced participants' performance; (2) the more difficult the goal, the fewer transactions were completed; and (3) while there were no differences in total profitability among the challenging goal, compromise goal, and no goal, the difficult goal condition had a significant and negative effect on the ability of participants to achieve profitable outcomes within the market. A discussion of these findings and directions for future research are presented. 相似文献
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Georg Steinhauser Johannes H. Sterba Eliezer Oren Michaela Foster Max Bichler 《Die Naturwissenschaften》2010,97(4):403-410
Seven pumice samples from excavations in North Sinai have been investigated with respect to their geochemical composition.
This type of volcanic rock has been used as an abrasive and thus has been an object of trade since antiquity. With the help
of Instrumental Neutron Activation Analysis, six of these Bronze Age samples could be correlated to their volcanic sources
on the islands of Santorini, Nisyros and Giali (Greece) using the typical element concentrations (“chemical fingerprint”).
The source of one pumice sample remains unidentified excluding, however, the Santorini eruption as a possible source. The
concluding section of this article discusses the possible contribution, however indirect, of the pumice from Sinai and elsewhere
in the Eastern Mediterranean to the controversial issue of the accurate date of the “Minoan” eruption of Santorini. 相似文献
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Max Hofmann Laetitia M. Navarro Steve Carver Peter H. Verburg Henrique M. Pereira 《Conservation biology》2015,29(4):1017-1027
Farmland abandonment takes place across the world due to socio‐economic and ecological drivers. In Europe agricultural and environmental policies aim to prevent abandonment and halt ecological succession. Ecological rewilding has been recently proposed as an alternative strategy. We developed a framework to assess opportunities for rewilding across different dimensions of wilderness in Europe. We mapped artificial light, human accessibility based on transport infrastructure, proportion of harvested primary productivity (i.e., ecosystem productivity appropriated by humans through agriculture or forestry), and deviation from potential natural vegetation in areas projected to be abandoned by 2040. At the continental level, the levels of artificial light were low and the deviation from potential natural vegetation was high in areas of abandonment. The relative importance of wilderness metrics differed regionally and was strongly connected to local environmental and socio‐economic contexts. Large areas of projected abandonment were often located in or around Natura 2000 sites. Based on these results, we argue that management should be tailored to restore the aspects of wilderness that are lacking in each region. There are many remaining challenges regarding biodiversity in Europe, but megafauna species are already recovering. To further potentiate large‐scale rewilding, Natura 2000 management would need to incorporate rewilding approaches. Our framework can be applied to assessing rewilding opportunities and challenges in other world regions, and our results could guide redirection of subsidies to manage social‐ecological systems. 相似文献
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