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Mark G. Cantwell Monique M. Perron Julia C. Sullivan David R. Katz Robert M. Burgess John King 《Environmental monitoring and assessment》2014,186(8):4841-4855
In this study, methods and approaches were developed and tested to assess changes in contaminant fluxes resulting from dam removal in a riverine system. Sediment traps and passive samplers were deployed to measure particulate and dissolved polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the water column prior to and following removal of a small, low-head dam in the Pawtuxet River, an urbanized river located in Cranston, RI, USA. During the study, concentrations of particulate and dissolved PAHs ranged from 21.5 to 103 μg/g and from 68 to 164 ng/L, respectively. Overall, temporal trends of PAHs showed no increases in either dissolved or particulate phases following removal of the dam. Dissolved concentrations of PCBs were very low, remaining below 1.72 ng/L at all sites. Particulate PCB concentrations across sites and time showed slightly greater variability, ranging from 80 to 469 ng/g, but with no indication that dam removal influenced any increases. Particulate PAHs and PCBs were sampled continuously at the site located below the dam and did not show sustained increases in concentration resulting from dam removal. The employment of passive sampling technology and sediment traps was highly effective in monitoring the concentrations and flux of contaminants moving through the river system. Variations in river flow had no effect on the concentration of contaminants in the dissolved or particulate phases, but did influence the flux rate of contaminants exiting the river. Overall, dam removal did not cause measurable sediment disturbance or increase the concentration or fluxes of dissolved or particulate PAHs and PCBs. This is due in large part to low volumes of impounded sediment residing above the dam and highly armored sediments in the river channel, which limited erosion. Results from this study will be used to improve methods and approaches that assess the short- and long-term impacts ecological restoration activities such as dam removal have on the release and transport of sediment-bound contaminants. 相似文献
815.
816.
Policies that arise out of conflict or collaboration between specific interest groups and government agencies are often explained
by theoretical constructs that fall under the umbrella of group theory. Triangulation theory is one of these constructs and
serves to explain the mutuality of interests that exist between government agencies and interest groups expressed as points
linking geometric forms. Conflict tends to occur when competing interest groups are excluded from the linkage, in this case
between the opponents and proponents of hormone herbicides in the Tala area in Natal, South Africa. In opposition to the use
of hormone herbicides were vegetable farmers and their supporters: in linked support were agricultural interest groups who
used hormone herbicides, the manufacturers of the herbicides, and the government agency responsible for agriculture. Because
of the influence exerted through mutual support by the proponents of hormone herbicides, the formulation of policy decisions
directed towards the resolution of the conflict was delayed. When the minister of agriculture finally intervened, the policy
decisions were designed to secure the support of those opposing the use of hormone herbicides by introducing issues that cut
across those maintaining the discord. 相似文献
817.
Mark Moody-Stuart 《生态毒理学报》2003,25(2):12-15
商业已经为可持续性发展进程建立了伙伴关系的基础 .通过确立目标和公开报告为实现这些目标应做的准备,可以保证建立工作伙伴关系愿望的实现 .在目前还没有可持续发展经济活动的地区,引进大大小小的商业企业 .市场是重要的,但是结构的调整也同样重要 .志愿的努力推动着事物向前发展 .为了全球的贸易、金融和环境的发展,有必要形成国际构架,商业界就需要与其他各界共同奋斗,确保对每一个单独的国家和企业的管理符合<全球契约>订立的基本标准 . 相似文献
818.
Remediation results depend on thorough consideration of all the forces that influence contaminant behavior, including how the contaminant is distributed and the site's hydrogeology, as well as the physical, chemical, and biological factors involved in contaminant mobility and persistence. This information supports a cleanup project's initial investigation, helping decide the goals of the later remediation method, the usefulness of specific technologies, and the method's ultimate performance. This article discusses how the principal environmental and chemical processes influence contaminant fate and transport and explores four case histories that illustrate how that influence can help predict whether a project's goals are achievable, whether the project is needed at all, and whether those goals were actually achieved. 相似文献
819.
Analytical procedures for the determination of nine organic booster biocides which are currently licensed for use in marine antifouling paints, and are thought likely to occur at concentrations in the ng 1−1 range in estuarine water samples, are reviewed. A robust multiresidue method for the determination of four compounds (chlorothalonil, dichlofluanid, diuron and Irgarol 1051) is suggested. A route for the development of a method for the analysis of zinc pyrithione is outlined, based on an extraction method and subsequent derivatisation prior to determination by HPLC with fluorescence detection. Methodology for Zineb, Kathon 5287, TCMS pyridine and TCMTB is less clearly defined. 相似文献
820.
Mark Pyron 《Behavioral ecology and sociobiology》1995,37(6):407-412
Neither size nor breeding color correlated with spawning success of male orangethroat darters, Etheostoma spectabile (Pisces, Percidae), under natural field conditions. When females were presented experimentally with a simultaneous choice they spent no more time in proximity to large than small males, and were subsequently no more likely to spawn with large than with small males. Females also displayed no preference for bright versus dull males. Males and females did not differ significantly in size. Etheostoma spectabile may lack sexual size dimorphism as a result of the lack of female choice for size and the ineffectiveness of male attempts to monopolize females, or selection may be for increased size of females. Males are not dwarfs because of sperm competition. Contest competition among males appeared to be important in initiating spawnings but many males obtained spawnings by participating in ongoing spawning events. Etheostoma spectabile is an example of a sexually dimorphic species with no evident female preference for male size or color. 相似文献