全文获取类型
收费全文 | 27693篇 |
免费 | 271篇 |
国内免费 | 245篇 |
专业分类
安全科学 | 797篇 |
废物处理 | 1113篇 |
环保管理 | 3858篇 |
综合类 | 4207篇 |
基础理论 | 7372篇 |
环境理论 | 11篇 |
污染及防治 | 7554篇 |
评价与监测 | 1752篇 |
社会与环境 | 1341篇 |
灾害及防治 | 204篇 |
出版年
2022年 | 212篇 |
2021年 | 231篇 |
2020年 | 166篇 |
2019年 | 223篇 |
2018年 | 379篇 |
2017年 | 359篇 |
2016年 | 578篇 |
2015年 | 495篇 |
2014年 | 727篇 |
2013年 | 2270篇 |
2012年 | 878篇 |
2011年 | 1164篇 |
2010年 | 926篇 |
2009年 | 1103篇 |
2008年 | 1249篇 |
2007年 | 1277篇 |
2006年 | 1109篇 |
2005年 | 960篇 |
2004年 | 934篇 |
2003年 | 900篇 |
2002年 | 891篇 |
2001年 | 1137篇 |
2000年 | 827篇 |
1999年 | 474篇 |
1998年 | 342篇 |
1997年 | 349篇 |
1996年 | 392篇 |
1995年 | 423篇 |
1994年 | 398篇 |
1993年 | 356篇 |
1992年 | 311篇 |
1991年 | 330篇 |
1990年 | 334篇 |
1989年 | 318篇 |
1988年 | 275篇 |
1987年 | 258篇 |
1986年 | 246篇 |
1985年 | 226篇 |
1984年 | 268篇 |
1983年 | 270篇 |
1982年 | 267篇 |
1981年 | 262篇 |
1980年 | 210篇 |
1979年 | 251篇 |
1978年 | 171篇 |
1977年 | 164篇 |
1976年 | 143篇 |
1975年 | 153篇 |
1973年 | 152篇 |
1972年 | 154篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
In a 1981 survey of 436 Florida citrus growers, 27 pesticide related poisoning incidents were reported that were to have taken place within one year of the interview date. From these reports it is possible to estimate that there are 376 citrus fieldworker related poisonings per year in Florida. This number of estimated poisonings may be developed into an incidence rate of 113 fieldworker poisonings per 10,000 fieldworkers. 相似文献
44.
Community evacuation following a chlorine release, Mississippi 总被引:1,自引:0,他引:1
On 7th September 1986, four miles north of Collins, Mississippi, a train transporting chlorine derailed. Two cars ruptured and gas escaped. As a result, 100 families were evacuated. To study the evacuation process, we conducted person-to-person interviews with sixty-two families staying in the evacuation center. Only 52.5% of the families received their first directive to evacuate directly from police or other officials. Delays in evacuating tended to be shorter when people were warned by the police and were told the reason for evacuating. Lack of personal transportation and preexisting health problems resulted in delays in evacuation. Concerns about evacuation included fear of looting, lack of a place to go, lack of transportation, difficulty in moving with children and elderly persons, and the need to take care of pets. One third of the interviewees reported feeling panic. Community evacuation procedures would be improved if: (1) officials contact all households directly; (2) the warning message addresses people's concerns; and (3) transportation is provided. 相似文献
45.
B. McNELIS 《Natural resources forum》1986,10(4):363-372
After several years of experimentation and demonstration, photovoltaic (PV) power is now firmly established for certain applications where reliable power is required in remote locations. The technology has recently matured to the point where PV is now an appropriate, cost-effective technology for village use. This paper reviews experience and presents economic comparisons between photovoltaic and conventional power systems. It is concluded that PV is cost-effective for individual home lighting and small loads such as radios, when compared with kerosene lamps and batteries. For mutiple uses PV is cost-effective compared with diesel generators for daily electricity demands up to around 20 kWh, depending on local conditions. 相似文献
46.
47.
B. A. Kerrigan 《Marine Biology》1997,127(3):395-402
The effects of food availability, female size, and social interactions on the quality of Pomacentrus amboinensis larvae at hatching were examined using two field-based experiments. In Experiment 1, food availability and female size significantly
influenced size, eye diameter and levels of yolk reserves of larvae at hatching. Small females (47 to 52 mm standard length,
SL) whose diets were not supplemented, produced the longest larvae (3.0 ± 0.01 mm total length, TL) with the least yolk reserves
(50.1 ± 1.04 μm2). Irrespective of female size, those that received additional food produced larvae with the largest yolk-sacs (large females:
87.60 ± 1.53 μm2; small females: 80.14 ± 1.24 μm2). In Experiment 2, interactions with conspecifics had a greater affect on the somatic development of larvae at hatching than
food availability. Increased social interactions resulted in larvae that were ⋍3% longer, with 2% greater head depth, than
larvae from females that spawned in isolation on the experimental reefs. Fed females produced larvae with ⋍20% more yolk than
larvae from females whose diets were not supplemented. All three factors (food availability, female size, and intensity of
social interactions) tested within these experiments vary spatially and temporally among reefs. There is the potential, therefore,
for larvae at the onset of the planktonic stage to vary in quality, level of development, and probability of survival.
Received: 12 August 1996 / Accepted: 26 August 1996 相似文献
48.
The amount of NO2 and NO produced by the machine smoking of cigarettes was determined for 15 commercial Canadian brands. Average yield of NO was 1.44 μmoles or about 13% of the average reported for American cigarettes. Levels of NO2 were less than 12% of NO and were probably due to the oxidation of NO. In order to assess the contribution of tobacco smoke to levels of NO in ambient air, 5 brands of cigarettes were smoked in 27 cubic meter controlled environment room. Ventilation conditions were either 2.5 or 5.0 air changes per hour (ACH) and each experiment was replicated 3 times for a total of 30 experiments. Ventilation rates of 0.3 and 1.5 ACH were also selected in a second series of experiments in which only one brand of cigarette was smoked. Least squares estimates for the effective ventilation rates were obtained in the usual manner after linearizing the decay portion of the NO time curve. In each of the experiments, the regression explained at least 95% of the variation in the levels of NO with time. Loss of NO due to factors other than ventilation appeared to be constant within experimental error and averaged 2.22 ACH. Equilibrium values for NO were grossly underestimated when results from currently accepted proecedures for smoke analysis were used in modeling the growth and decay of NO. Goodness-of-fit was improved when equilibrium values were estimated based on observed levels in ambient air. This approach may be more suitable for evaluating the potential contribution of cigarette smoke to levels of indoor air pollutants. 相似文献
49.
Bruce C. Glavovic 《Journal of Environmental Planning and Management》1996,39(4):483-506
Protected areas in developing countries play a vital role in promoting the ideal of sustainable development.But 'people-park'conflicts are commonplace,threatening the future of these areas and the long term well-being of local communities. Surprisingly, little attention has been given to applying lessons learned in conflict studies to people-parkconflicts. In contrast to traditional adversarialresponses, negotiated approaches offer considerable potential for transforming people-park conflicts into mutually beneficial relationships.Experiencesin the Richtersveldregion of South Africa demonstrate the cardinal role negotiation can play in addressing key issues underlying people-park conflicts. 相似文献
50.
Coping with riverbank erosion hazard and displacement in bangladesh: survival strategies and adjustments 总被引:2,自引:0,他引:2
As a deltaic plain, Bangladesh annually experiences riverbank erosion hazard due to sudden and rapid channel shifting, particularly in the major floodplain areas of the country. Consequently, valuable cultivable land is lost; also village settlements, markets and towns are destroyed, displacing tens of thousands of people. This paper examines the magnitude of river channel migration and encroachment on land, and the nature of human adjustment systems in the Brahmaputra–Jamuna floodplain, by investigating aspects of the social and cultural dynamics of resettlement of the displaced people. Some policy measures are recommended to improve the ability of the people in the floodplain to cope with these hazards. 相似文献