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961.
ABSTRACT. Silver iodide is currently the most favored cloud seeding material in weather modification projects. While the literature indicates that its ecological effects are likely to be insignificant, its disposition in the terrestrial ecosystem after snow melt has not been adequately studied. Silver levels in soil, plant and litter material are being monitored twice a year on a mountainous area in southwestern Colorado, to determine whether annual accretion from cloud seeding can be measured with current techniques and whether significant changes in silver concentration take place in grass, aspen, and spruce communities. One AgI generator site is also being monitored. Comparison of silver concentrations in terrestrial components of the target area indicates no measurable increase after the first winter's seeding. On an ash basis, spruce foliage and litter contain about four times as much silver as soil. On a dry weight basis, soil from all three plant communities contains about six times as much silver as foliage. Consistent increases in silver concentration were found in soil and pine foliage within 200 meters of one generator site.  相似文献   
962.
Pathogens are a significant driver of biodiversity loss. We examine two wildlife disease management strategies that have seen growing use, sometimes in combination: (i) trapping-and-culling infectious animals (disease control), and (ii) trapping-and-translocating healthy animals to a reserve, with possible future reintroduction. A reserve can improve conservation when there is no disease. But, when infection exists, we show investing in the reserve may counteract disease control. We find jointly pursuing both strategies is sub-optimal when the reserve is costly to maintain. Numerically, we examine management of Devil Facial Tumor Disease, which has generated extinction risks for Tasmanian Devils. Disease control (though not eradication) is generally part of an optimal strategy, although a reserve is also optimal if it can be maintained costlessly. This implies preserving the original population by addressing in situ conservation risks, rather than translocating animals to a reserve and giving up on the original population, is generally the first-best.  相似文献   
963.
The flora of liverworts has been studied in the vicinity of the Bil’chenok glacier (the Ushkovskii volcano, Kamchatka), which is in a zone of volcanic ash fallout. Specific complexes of liverworts growing on young moraine and ash deposits have been identified. These complexes are dominated by thallose marchantioid species. Under the effect of periodic ash fallout (in the absence of glacial activity), communities are formed that contain increased proportions of xerophytes and species preferring sites with a disturbed ground vegetation cover.  相似文献   
964.
中国土壤资源特点与粮食安全问题   总被引:7,自引:2,他引:5  
土壤资源是粮食生产的基础,也是粮食安全的核心。文章在研究我国土壤资源特点的基础上,系统阐述我国粮食安全正面临着耕地减少、粮食减产的挑战。提出要解决我国耕地土壤和粮食安全问题,必须实施“藏粮于土”的行动计划,全面提高我国土壤资源的综合生产能力,其主要内容是:稳定耕地面积和粮食播种面积,实施基本农田严格保护机制;开发土壤潜力,提高粮食综合生产能力;加强生态环境建设,建立有弹性有应变能力的种植制度;防治土壤污染,保障粮食安全;适度开荒复垦,充分利用非耕地资源。  相似文献   
965.
外来植物物种的引进对路域生态的影响   总被引:8,自引:0,他引:8  
刘龙 《交通环保》2003,24(2):20-22,48
根据植被恢复的规律和公路建设的特点,分析外来植物物种在路域内的应用现状。目前本地原有的植物物种,不能满足公路路域植被迅速恢复的要求,所以在绿化施工过程中大量采用外来植物物种,但在引进的过程中存在着一定的危险性,从生态学角度分析了外来物种对路域生态环境及其周边生态环境的影响。并提出防范措施。  相似文献   
966.
Latin America comprehends notable variations in terms of natural environment, availability of natural resources, living standards, and demographic patterns. Latin America is a mosaic of cultures, post- and pre-Columbian. The rich variety of life forms discovered and described by chroniclers and traveling naturalists in the Neotropics contributed to the proposal, in mid-XVIIIth century, of a new system of classification and a scientific code of nomenclature for all organisms. Biodiversity was, for many centuries, a source of resources to be exploited in natura. In scientific circles, its inventory became the domain of taxonomists. But modern technology showed how important the miriad of life forms really are as sources of chemical molecules to be engineered as drugs and reassembled as novel manufactured products. We are on the brink of a new agricultural and medical revolution, thanks to the techniques of genetic engineering, which will lead eventually to the elimination of hunger and malnutrition.In this essay, the Brazilian environmental and social heterogeneity will serve as an example to illustrate some key points, which have influenced sustainability policies. The Amazon deforestation and indigenous knowledge (IK), subjects often associated with areas of high biodiversity, are usually the focus of environmental debates. The importance of IK in integrating development, reducing poverty and sustainability are considered together with the intellectual property rights of native populations.In the World Summit on Sustainable Development (WSSD) Implementation Plan, a few paragraphs were dedicated to Latin America, because of the pre-existing Action Platform on the Road to Johannesburg 2002, approved in Rio de Janeiro in October 2001. This paper calls attention to the need to draw up specific environmental policies for a region which shows an extremely high cultural and biological diversity, associated with a high availability of forests and water, among other resources.  相似文献   
967.
Abstract:  Disease is increasingly recognized as a threat to the conservation of wildlife, and in many cases the source of disease outbreaks in wild carnivores is the domestic dog. For disease to spill over from a domestic to a wild population, three conditions must be satisfied: susceptibility of the wild species, presence of the disease agent in the domestic population, and contact between the two populations of interest. We investigated the potential for disease spillover from the domestic dog population to the wild carnivore population in the Isoso of Bolivia, an area of tropical dry forest contiguous with a national park. Using questionnaires and discussions with residents, we gathered data on the demography of dogs in the Isoso, including adult and neonatal mortality, litter size, and hunting frequency. We analyzed a large data set containing self-recorded information on hunting in various communities of the Isoso to determine the extent of dog participation in hunting and the duration of hunting trips. Finally, we took blood samples from dogs in the Isoso for a serosurvey of common canine pathogens. More than 95% of dogs had positive titers to canine distemper virus and canine parvovirus. There was also a high seroprevalence in dogs for other pathogens, a high population turnover of dogs (which may allow diseases to be maintained endemically), and frequent opportunities for contact between domestic and wild carnivores. Based on our results and the susceptibility of wild species previously reported in the literature, domestic dogs represent a disease risk for wildlife in the Bolivian Isoso.  相似文献   
968.
论述了苏州高新区根据科学发展观的要求,坚定发展循环经济的理念;从企业、企业群和社会三个层面全面开展发展循环经济的实践,建设循环型生态工业园;落实“三个机制”,实施“五大创新”,取得经济与环境的双赢,推动了区域社会、经济与环境的协调发展。  相似文献   
969.
本文分配的了国内外工业生态化的研究现状,阐述了企业层次工业生态化的内涵,从生产系统和管理体系两方面提出工业生态化企业模式,分别涉及采购、生产、销售、消费和企业文化、组织结构、管理机制等七方面要素,并以水泥企业为例进行生态化生产系统的论述。  相似文献   
970.
Abstract:  The Gaia hypothesis, which proposes that Earth's biota and material environment form a self-regulating system, has been influential in conservation biology, but it has not translated into specific guidelines. Proponents of phylogenetics and ecology often claim primacy over the foundations of conservation biology, a debate that has deep roots in philosophy and science. A more recent claim is that conservation efforts should protect evolutionary processes that will allow diversification. Phylogenetics, ecology, and evolution all have legitimate roles in conservation, when viewed in a temporal perspective. Phylogenetic studies identify the bioheritage of past species radiations, ecology preserves the life-support systems for these lineages in the present, and evolutionary processes allow adaptation of these lineages to novel challenges in the future. The concept of temporal domains in conservation (past, present, future) has an appropriate metaphor in the Norse worldview known as the Orlog. In this body of mythology, three sisters tend the tree of life and fend off a dragon gnawing at the roots. The names of these sisters, Urd, Verdandi, and Skuld, translate to Past, Present, and Future. In Viking mythology, the threads of life cannot persist without the cooperation of these sisters. In the science of conservation biology, they represent the handmaidens of Gaia–three scientific disciplines that can succeed only with a spirit of familial cooperation.  相似文献   
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