全文获取类型
收费全文 | 4958篇 |
免费 | 97篇 |
国内免费 | 76篇 |
专业分类
安全科学 | 221篇 |
废物处理 | 243篇 |
环保管理 | 1285篇 |
综合类 | 446篇 |
基础理论 | 1139篇 |
环境理论 | 5篇 |
污染及防治 | 1216篇 |
评价与监测 | 342篇 |
社会与环境 | 180篇 |
灾害及防治 | 54篇 |
出版年
2023年 | 28篇 |
2022年 | 26篇 |
2021年 | 51篇 |
2020年 | 33篇 |
2019年 | 64篇 |
2018年 | 79篇 |
2017年 | 94篇 |
2016年 | 120篇 |
2015年 | 119篇 |
2014年 | 113篇 |
2013年 | 555篇 |
2012年 | 183篇 |
2011年 | 262篇 |
2010年 | 199篇 |
2009年 | 202篇 |
2008年 | 262篇 |
2007年 | 265篇 |
2006年 | 245篇 |
2005年 | 171篇 |
2004年 | 197篇 |
2003年 | 199篇 |
2002年 | 179篇 |
2001年 | 84篇 |
2000年 | 108篇 |
1999年 | 108篇 |
1998年 | 75篇 |
1997年 | 67篇 |
1996年 | 74篇 |
1995年 | 72篇 |
1994年 | 64篇 |
1993年 | 70篇 |
1992年 | 72篇 |
1991年 | 44篇 |
1990年 | 54篇 |
1989年 | 45篇 |
1988年 | 33篇 |
1987年 | 40篇 |
1986年 | 47篇 |
1985年 | 43篇 |
1984年 | 44篇 |
1983年 | 51篇 |
1982年 | 38篇 |
1981年 | 54篇 |
1980年 | 45篇 |
1979年 | 23篇 |
1978年 | 25篇 |
1977年 | 17篇 |
1976年 | 12篇 |
1975年 | 14篇 |
1971年 | 13篇 |
排序方式: 共有5131条查询结果,搜索用时 31 毫秒
11.
12.
13.
Steinar Sandφy 《Ambio-人类环境杂志》2003,32(3):162-164
20世纪70和80年代,"酸雨"成为一个主要公共政策问题.在加拿大和北欧的斯堪的纳维亚半岛的酸化水体中,生物群落及生境遭到频繁破坏,诸如土著鲑鱼和鳟鱼种群受损乃至灭绝的现象屡见不鲜. 相似文献
14.
15.
Whereas past research has treated co-management of common pool resources as if villagers and project implementing authorities
were the only relevant actors, numerous external factors beyond the control of these two partners create barriers to successful
co-management. This paper draws on discussions with Forest Department officials to examine the influence of these forces on
the outcomes of Joint Forest Management (JFM) in Tamil Nadu, India. An empirical inquiry into the operational aspects of JFM
indicates the important roles of political parties, powerful people, and other state institutions and functionaries as well
as the flow of foreign funding. Further, the strong demand by local people for socio-economic development interventions as
opposed to improvement of degraded forests belittles the role of the Forest Department relative to other departments. Numerous
other conditioning factors and relationships are explored. The authors call for reforms in public governance to allow better
participation of all the actors involved for this participatory management approach to succeed and sustain. 相似文献
16.
This paper summarizes developments made in the field of waste-to-energy technology between the 1980s and the present. In the USA, many waste-to-energy systems were developed in the 1980s and early 1990s. These plants generated power relatively efficiently (typically 23%) in 60 bar/ 443 degrees C boilers. Unfortunately, the development came to a stop when the US Supreme Court rejected the practice of waste flow control in 1994. Consequently, waste was directed to mega-landfills, associated with very negative environmental impacts. However, given landfill taxes and increased fuel prices, new waste-to-energy projects have recently been developed. Attractive premiums for renewable power production from municipal waste have been introduced in several European countries. This triggered important innovations in the field of improved energy recovery. Examples of modern waste-to-energy plants are Brescia and Amsterdam with net efficiencies of 24 and 30%, respectively. Incineration is traditionally preferred in Japan due to space constraints. New legislation promoted ash melting or gasification to obtain improved ash quality. However, these processes reduce the efficiency in terms of energy, cost and availability. A new oxygen-enriched waste-to-energy system is under development in order to better achieve the required inert ash quality. 相似文献
17.
John F. Potter 《The Environmentalist》2006,26(4):329-329
18.
19.
In order to keep subscribers up-to-date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of prenatal diagnosis. Each bibliography is divided into 17 sections: 1 Books, Reviews & Symposia; 2 General Interest; 3 Normal Fetal Development; 4 Gametogenesis and Pre-implantation Diagnosis; 5 First Trimester Diagnosis; 6 Second Trimester Diagnosis; 7 Fetal Diagnosis by Ultrasound and Other Imaging; 8 Maternal Screening; 9 Screening for Carriers of Genetic Abnormality; 10 Technological Developments; 11 Confined Placental Mosaicism and Uniparental Disomy; 12 Molecular Cytogenetics; 13 Fetal Cells in Maternal Circulation; 14 Fetal Therapy; 15 Psychosocial Aspects; 16 Epidemiology and Environmental Factors; 17 Developmental Pathology. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted 相似文献
20.
Summary
Ips duplicatus withI. typographus co-inhabiting Norway spruce (Picea abies (L.) Karst.) would benefit from a pheromone blend distinct from that of the larger competitorI. typographus. GC-MS analysis showed thatI. duplicatus males feeding in the host produced ipsdienol (Id),cis-verbenol (cV),trans-verbenol (tV), myrtenol (Mt), andE-myrcenol (EM) and traces of 2-methyl-3-buten-2-ol (MB).I. duplicatus produced Id in approximately racemic form (48.9-54.5% (+)-(S)-isomer). The amounts of Id and EM released over a 9 day period had a maximum of 250 and 5 ng/h/male, respectively, on day 2. Exposure ofI. duplicatus males to myrcene and -pinene resulted in the production of small amounts of Id, cV, tV, Mt, andtrans-pinocarveol, but not of EM. In laboratory bioassays with walking beetles, the pheromone component Id alone was weakly attractive while EM was inactive, but in binary combination with Id strongly synergized attraction. A combination of EM and Id at a release rate equivalent to 100–200 males was more attractive in the field than 70 unmated males in a spruce log. The addition of myrcene ( a suggested pheromone precursor of Id) to Id did not enhance trap caches, while addition of EM increased catches > 10-fold. Subtracting EM from a blend of Id, EM, cV and MB drastically reduced trap catches while subtraction of cV or MB or both had no significant effect. Addition of EM over a wide concentration range to the synthetic pheromone ofI. typographus did not reduce the attraction of females of this species in the laboratory. A two-species pheromone interaction field test releasingI. typographus pheromone components (MB + cV) at 10–1000 male equivalents (ME) andI. duplicatus pheromone (Id + EM) at 0, 10–1000 ME in all possible combinations showed both positive intraspecific dose-response effects and an interspecific inhibition. Higher release rates of EM appeared to inhibitI. typographus, especially males. In a tree colonization model, the response of the two competing species to their respective pheromones show a good separation during the mass-attack with a small initial cross-attraction. It remains to be shown whether either of the two pheromone systems have in fact evolved in the present sympatry, or if they are an incidental effect of ancestry of these phylogenetically distantIps. 相似文献