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901.
902.
本文在分析湖北省局部地区自然疫源变化及疾病趋势的基础上,指出了南水北调中线工程可能对地氟病、血吸虫、疟疫、乙脑及其它水源性疾病所带来的影响,并提出了建设性的建议和对策。 相似文献
903.
Giovanni Giavelli 《Environmental management》1989,13(4):425-433
Environmental research is characterized in each of its successive phases by a strong interdisciplinarity. A rotational groups system (RGS) method is proposed as an instrument to encourage interaction among researchers from fields that are traditionally far apart. Meetings conducted with the RGS procedure involve all the researchers, who, in repeated and topical encounters, are able to exchange information on a wide variety of environmental subjects. These meetings can be arranged according to a special calendar, through a series of phases treating different aspects of the same subjects to be discussed, and above all, referring to specific themes and working guidelines organized on the basis of criteria designed to favor an exchange of ideas and constructive discussion. At the end, the plenary assembly edits an overall resume of the proceedings, and votes on the final resolution, which brings together all the conclusive opinions regarding the themes discussed. 相似文献
904.
Janusz R. Rydzewski Saeed Nairizi 《Journal of the American Water Resources Association》1979,15(2):316-325
ABSTRACT: The deliberate underwatering of a larger land area, as practiced in Southern Asia, has provided impetus for a systematic investigation into the effects of designing projects for crop water deficits on Benefit-Cost performance. The study began with the derivation, from published experimental results, of functions relating ultimate crop yield to the magnitude and timing of water deficits, i.e., of the productivity of irrigation water. To obtain the net benefit of the project, the relation between the harvested area and output and the on-farm production costs was then suggested. The cost of supplying the irrigation water to the proposed area and of distributing and applying it to the field was determined, thus completing the Benefit-Cost equation. A computer simulation model was then established to search for the irrigation project design capacity and area to maximize the net present value in the Benefit-Cost analysis for the development proposed. 相似文献
905.
袁大祥 《中国安全科学学报》1992,2(2):35-40
分析了我国高等学校开设安全工程专业的发展状况,提出安全工程专业应以安全科学技术知识为主体,兼顾生产知识,设置专业基础课程和专业课程,形成安全工程的专业特性。 相似文献
906.
Peter F. M. McLoughlin 《Journal of the American Water Resources Association》1988,24(1):189-200
ABSTRACT: Southeast Asian nations with extensive water management systems have numerous candidate and ongoing programs and projects. They cannot possibly all be funded and implemented simultaneously in any serious way. Choices must be made. But how to select? What criteria can assist with the screening in an acceptable manner, particularly in the near absence of useful technical and economic information across them all. This paper suggests a methodology by which assessment criteria can be constructed which conforms to any given national information base and development needs. Criteria can be weighted one against the other in their relative importance. For each criterion a ranking scale puts the “best” (most, highest) at one end and the “worst” (least, lowest) at the other. Each candidate project is then subjected to these consistent assessment methods for a weighted “score.” Key criteria normally have surrogate measures depending on information available. Criteria are of three sorts: sheer volume, e.g., of a specific use, a benefit; ratios and relations, e.g., A as percent of B; and other more subjective criteria, e.g., regional or income distribution impacts. The basic criteria include, for example, time to full benefits (minimize), OM & R as percent of investment (minimize), and permanent rural jobs created (maximize). 相似文献
907.
908.
密切值法在污水土地处理工程选址中的应用 总被引:4,自引:0,他引:4
本文对密切值法在污水土地处理工程选址中的应用进行了探讨,通过实例分分析看出该方法科学可行且简易。 相似文献
909.
Dominance, access to colonies, and queues for mating opportunities by male boat-tailed grackles 总被引:3,自引:0,他引:3
Joseph P. Poston 《Behavioral ecology and sociobiology》1997,41(2):89-98
Species characterized by female-defense polygyny have extreme variance in male mating success. Many studies have considered
alternative male strategies for access to females, but few have considered age-specific strategies. Male boat-tailed grackles
(Quiscalus major) compete for access to colonies of females and form linear dominance hierarchies. I observed two groups of males that competed
for females at seven colonies. Dominance rank was significantly correlated with mass, but not after controlling for age. In
contrast, the correlation between dominance rank and age remained significant after controlling for mass. Older males dominated
younger males and dominance relationships were very stable. Thus, dominance hierarchies represent queues for mating opportunities.
A male's rank in the hierarchy determined how closely he approached a colony. Furthermore, males of all ranks prevented lower-ranked
individuals from approaching the colonies. Dominance rank thus determined access to nesting females. One top-ranking male's
loss of mass over the course of the breeding season presumably reflected the energetic cost of defending females, but he maintained
his position in the hierarchy despite the small loss of mass. One alpha male held a colony for at least 4 years, and the ages
of males from two queues indicated that males wait 6 or more years before becoming an alpha male. Therefore, most males die
before acquiring a colony of females. Spatial structure such as that documented here could obscure recognition of queues and
explain why they have not been documented in more species.
Received: 13 May 1996 / Accepted after revision: 26 April 1997 相似文献
910.
玄武湖引水工程的环境效益分析 总被引:6,自引:0,他引:6
张丹宁 《环境监测管理与技术》1995,7(3):17-18,25
从现有引水工程环境实施效果入手,通过小试试验,响应模型计算及投资效益分析,提出了引水工程的改进方案。 相似文献