全文获取类型
收费全文 | 1928篇 |
免费 | 57篇 |
国内免费 | 21篇 |
专业分类
安全科学 | 91篇 |
废物处理 | 71篇 |
环保管理 | 438篇 |
综合类 | 192篇 |
基础理论 | 548篇 |
环境理论 | 5篇 |
污染及防治 | 446篇 |
评价与监测 | 131篇 |
社会与环境 | 58篇 |
灾害及防治 | 26篇 |
出版年
2023年 | 19篇 |
2022年 | 33篇 |
2021年 | 48篇 |
2020年 | 26篇 |
2019年 | 42篇 |
2018年 | 55篇 |
2017年 | 62篇 |
2016年 | 81篇 |
2015年 | 51篇 |
2014年 | 66篇 |
2013年 | 157篇 |
2012年 | 88篇 |
2011年 | 134篇 |
2010年 | 86篇 |
2009年 | 101篇 |
2008年 | 115篇 |
2007年 | 110篇 |
2006年 | 110篇 |
2005年 | 62篇 |
2004年 | 53篇 |
2003年 | 65篇 |
2002年 | 55篇 |
2001年 | 32篇 |
2000年 | 47篇 |
1999年 | 23篇 |
1998年 | 20篇 |
1997年 | 12篇 |
1996年 | 21篇 |
1995年 | 18篇 |
1994年 | 23篇 |
1993年 | 11篇 |
1992年 | 11篇 |
1991年 | 10篇 |
1990年 | 9篇 |
1989年 | 13篇 |
1988年 | 13篇 |
1987年 | 12篇 |
1986年 | 12篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 11篇 |
1982年 | 13篇 |
1981年 | 15篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1975年 | 4篇 |
1969年 | 4篇 |
1958年 | 2篇 |
排序方式: 共有2006条查询结果,搜索用时 953 毫秒
111.
112.
In this study, we analyze the evolution of Canada's mining industry from 1929 to 2006, focussing on the determinants of the number of firms in the industry and why this number changed over that period. Most empirical studies of industry evolution have focused on manufacturing industries that share similar structural characteristics. Perhaps because of this, extant models of industry evolution tend to ignore industry-specific and national-specific factors that can cause atypical trajectories, that is, heterogeneous industry evolution. Initial inspection of the Canadian mining industry shows that it is atypical in that it exhibits “negative skew” over time in the number of firms rather than the typical “positive skew.” We review two dominant theoretical approaches to industry evolution: the density-dependence theory and variants of industrial organization economics. We also consider possible sources of industry evolution heterogeneity, focussing particularly on “regulatory punctuation”. Using Canadian mining data, we find that the traditional models do not fully explain the changes in population size in Canada's mining industry. As a result, we introduce a number of hybrid models. The results from these hybrid models suggest that Canadian-specific regulatory punctuations, particularly the introduction of significant new taxes, environmental legislation, and incentives have shaped the trajectory of mining firm participation. 相似文献
113.
A factor analytic study of attitudinal structure and its impact on rural landowners' access policies
Previous research has shown that rural landowners' hunter access policies are determined in large part by their attitudes
towards hunters, legal liability, conservation, and economic incentives. The results of this study support this research and
indicate that East Texas, USA, landowners' decisions to allow or restrict access are based, in part, on attitudes toward hunter
behavior, hunting as a social activity, leasing as a management practice, and a perceived obligation toward wildlife stewardship.
Attitude-based profiles of landowners who adopted one of four access policies are compared. 相似文献
114.
Christian Roy Bruno de Caumia Daniel Blanchette Hooshang Pakdel Genevive Couture Annette E. Schwerdtfeger 《补救:环境净化治理成本、技术与工艺杂志》1994,5(1):111-130
A vacuum pyrolysis process was used for the remediation of hydrocarbon–contaminated soils from “Les Vidangeurs de Montréal” site in Mascouche in the province of Québec, near Montréal. Ten samples were tested on a laboratory scale batch reactor, and one sample was tested on a prototype process development unit. The process is simple, efficient, reliable, and economically competitive with other existing technologies. The vacuum pyrolysis process efficiently treated soils contaminated with a variety of pollution levels and types, irrespective of the soil matrix, providing treated soils meeting the A criterion (noncontaminated, residential level) of the Ministry of Environment Québec (MENVIQ). The pyrolytic oil and the noncondensable pyrolytic gases can be used as makeup fuel in the process, because they have a high calorific value and their combustion should not pose any emission problems. The waterphase effluent must be treated before discharge. 相似文献
115.
Daniel H. Hoggan John C. Peters Werner Loehlein 《Journal of the American Water Resources Association》1987,23(6):1141-1147
ABSTRACT: The Pittsburgh District, U.S. Army Corps of Engineers, is responsible for operating two multipurpose reservoirs in the 7384 square mile (19198 square kilometer) Monongahela Basin. A third reservoir, presently under construction, will soon be operating. The real-time forecasting of runoff for operational purposes requires simulation of snow accumulation and snowmelt throughout the Basin during the winter season. This article describes capabilities of SNOSIM, a model being developed for performing such simulation. The application of this model as part of a comprehensive system of water control software, and some initial simulation results are presented. 相似文献
116.
117.
Daniel Little 《Journal of Agricultural and Environmental Ethics》1988,1(1):41-58
This article considers the dispute between moral economy and rational peasant theories of agrarian societies in application to problems of collective action. The moral-economy theory holds that traditional peasant society is organized cooperatively through shared moral values and communal institutions; while the rational-peasant theory maintains that peasant society shows the mark of rational individual calculation, leading to free-rider problems that undermine successful collective action. This article offers an abstract model of a traditional village and assesses the applicability of recent qualifications of the collective action argument to this model. It will emerge that the social characteristics of the traditional village embody features that facilitate collective action by rational peasants. 相似文献
118.
David Berryman Bernard Bobe Daniel Cluis John Haemmerli 《Journal of the American Water Resources Association》1988,24(3):545-556
ABSTRACT: A review of nonparametric tests for trend leads to the conclusion that Mann-Whitney, Spearman, and Kendall tests are the best choice for trend detection in water quality time series. Recently these tests have been adapted to account for dependence and seasonality in such series (Lettenmaier, 1976; Hirsch, et al., 1972; Hirsch and Slack, 1984). For monotonic trends, a procedure allowing to select the pertinent tests considering the characteristics of time series is proposed and the practical limitations of the tests are also brought out. This procedure has been applied to identify the appropriate trend detection test for the time series of nine water quality parameters at Lake Laflamme (Québec). When a time series can be tested with the Mann-Whitney, Kendall, Spearman, or Lettenmaier (1976) test, the number of observations required to detect trends of a given magnitude, for selected significance and power levels can be calculated with the power function of the t test. When the test proposed by Hirsch, et al. (1984), Hirsch and Slack (1984), or Farrell (1980) need to be used, the number of observations can only be estimated approximately from the results of empirical power studies. 相似文献
119.
This study investigates whether departments performing the same functions in different firms incur similar changes in structural configuration in response to industry-wide stimuli. Based on the proposition that the context of functional departments is similar across firms, changes in differentiation, integration, and perspective are hypothesized. Managers' perceptions of the validity of a series of statements to conditions five to 10 years ago and to present conditions are contrasted and show statistically significant shifts in these structural configurations. This change is confirmed by the analysis of responses of other managers in different departments within the same firms. Correlation analysis shows significant agreement among alternative measures of the same aspects of structure, and significant comovement among different structural dimensions. The later result supports the quantum theory of organizations. 相似文献
120.
Hypotheses were developed based on a coping model that views political behaviour (voice) as a fight response and turnover (exit) as a flight response to job stress. Data were collected from a group of professional, public employees and turnover dates were obtained for the group 13 months after completion of questionnaires. Multiple regression analysis was employed to test hypotheses. Stressors of interest were person-environment fit (P-E fit), role conflict (RC), and role ambiguity (RA). Psychological strains (job dissatisfaction and lowered commitment) were hypothesized to mediate the stressor-coping behaviour relationship. Turnover (TO) behaviour was the ultimate organizationally relevant outcome of coping behaviours. Job satisfaction and commitment were significantly related to intentions to leave. Political action was directly related to P-E fit and this relationship was not mediated by satisfaction or commitment. The relationship between RA and politics was moderated by commitment. Less committed employees tended to exhibit political behaviour in response to RA. Both coping responses (intentions to leave and political action) predicted significant portions of retention/turnover variance. 相似文献