全文获取类型
收费全文 | 5476篇 |
免费 | 27篇 |
国内免费 | 25篇 |
专业分类
安全科学 | 131篇 |
废物处理 | 296篇 |
环保管理 | 432篇 |
综合类 | 828篇 |
基础理论 | 1357篇 |
环境理论 | 1篇 |
污染及防治 | 1351篇 |
评价与监测 | 396篇 |
社会与环境 | 709篇 |
灾害及防治 | 27篇 |
出版年
2023年 | 42篇 |
2022年 | 76篇 |
2021年 | 59篇 |
2020年 | 29篇 |
2019年 | 42篇 |
2018年 | 75篇 |
2017年 | 90篇 |
2016年 | 110篇 |
2015年 | 70篇 |
2014年 | 146篇 |
2013年 | 416篇 |
2012年 | 168篇 |
2011年 | 241篇 |
2010年 | 214篇 |
2009年 | 219篇 |
2008年 | 253篇 |
2007年 | 250篇 |
2006年 | 240篇 |
2005年 | 207篇 |
2004年 | 187篇 |
2003年 | 214篇 |
2002年 | 175篇 |
2001年 | 254篇 |
2000年 | 161篇 |
1999年 | 101篇 |
1998年 | 41篇 |
1997年 | 58篇 |
1996年 | 53篇 |
1995年 | 60篇 |
1994年 | 64篇 |
1993年 | 59篇 |
1992年 | 58篇 |
1991年 | 61篇 |
1990年 | 66篇 |
1989年 | 52篇 |
1988年 | 56篇 |
1987年 | 54篇 |
1986年 | 55篇 |
1985年 | 41篇 |
1984年 | 47篇 |
1983年 | 47篇 |
1982年 | 48篇 |
1980年 | 30篇 |
1979年 | 32篇 |
1978年 | 29篇 |
1977年 | 28篇 |
1976年 | 28篇 |
1974年 | 31篇 |
1973年 | 30篇 |
1972年 | 27篇 |
排序方式: 共有5528条查询结果,搜索用时 93 毫秒
451.
A. Bleed H. P. Nachtnebel I. Bogardi R. J. Supalla 《Journal of the American Water Resources Association》1990,26(3):479-487
ABSTRACT: Two case studies highlighting the institutional arrangements and decision-making processes used to attempt to allocate water on large scale river systems in two countries are presented. In both cases the implementation of river plans has been blocked by conflicts between those who wish to use water for irrigation, hydropower, or municipal purposes and those who wish to maintain instream flows for fish and wildlife. To date conflict has blocked the implementation of a large hydropower scheme on the Danube River, downstream from Vienna, Austria, and the construction of municipal and agricultural projects, as well as the relicensing of an existing hydropower facility on the Platte River in Nebraska. Analysis of the decision-making processes and institutional settings of both cases led to the identification of problem areas and development of recommendations that would support the achievement of compromise solutions for management. 相似文献
452.
James I. Herbert 《组织行为杂志》1990,11(6):433-446
The biographical interview method was used to study the lives of 10 black male entrepreneurs. The findings of this investigation supported Levinson's theory of developmental periods. The concept of evolving life structure was found to be vibrant and viable. Because of the impact of racial dynamics and racism, on the men's lives, two new developmental tasks of adult psychosocial development are proposed: (1) to form an individual racial identity that both acknowledges and frees the individual of their own racism and prejudices, and (2) to form an individual self-concept dedicated to the eradication of racial discrimination and racial prejudice from society. 相似文献
453.
129I is one of the more hazardous nuclides occurring in radioactive waste. In the form of I−, its most likely speciation, it is poorly sorbed on most geologic media. Several workers have suggested the use of silver to precipitate I− as the insoluble AgI, in a cemented waste form, or as a “getter”. The efficacy of this procedure is examined by experiment, in conjunction with thermodynamic predictions.The addition of AgNO3 to Portland cement leads to coprecipitation with C-S-H, with low Ag solubilities ( 10 μmg/L); 2–;3 orders of magnitude lower than predicted (from Ag2O). AgI is stable in these matrices, with low aqueous I concentrations (<2 mg/L). In 85% BFS-15% OPC pastes, AgI is unstable due to redox and complexation reactions, with much I− passing into solution; concentrations up to 900 mg/L were observed. It is shown that repository conditions, on closure, are also likely to induce solubilisation of I− from AgI. It is concluded that the use of Ag is unlikely to significantly improve the immobilisation properties of the near field for radioiodine. 相似文献
454.
Bernard I. Logan 《Journal of Agricultural and Environmental Ethics》1989,2(3):191-207
Food security and food self-sufficiency are important regional goals for the Southern African Development Coordination Conference (SADCC). In the long run, success in these areas would reduce the incidence of drought-related mass starvation and the epidemic of malnutrition and undernutrition that exists among some tribal groups. For food production to improve, the governments must commit themselves to increasing the access of peasant farmers to critical agricultural inputs. If they do not take proper action in this area of development planning, domestic food production is likely to stagnate or decline. This study is a broad examination of the relationship between government expenditures on imported inputs and the performance of the domestic food subsector. Because much data on government spending and agricultural production in Africa are unavailable, and those in published form are of suspect validity, the study is undertaken largely as a conceptual overview. The empirical analyses are conducted, therefore, largely to provide a staging ground for the conceptual arguments. 相似文献
455.
John R. Thene Heinz G. Stefan Ekaterini I. Daniil 《Journal of the American Water Resources Association》1989,25(6):1189-1198
ABSTRACT: A method to evaluate the effect of hydropower development on downstream dissolved oxygen (DO) is presented for a low head dam. Water, previously aerated during release over spillways and under gates, is diverted through the hydropower facility without further aeration. The oxygen transfer that occurs as a result of air entrainment at the various release points of a dam is measured. Oxygen transfer efficiencies are calculated and incorporated into an oxygen transfer model to predict average release DO concentrations. This model is used to systematically determine the effect of hydropower operation on downstream DO. Operational alternatives are investigated and a simple operational guide is developed to mitigate the effects of hydropower operation. Combinations of reduced generation and optimal releases from the dam allow the hydropower facility to operate within DO standards. 相似文献
456.
B. Lussier G. E. Mohr I. C. Goulter 《Journal of the American Water Resources Association》1989,25(1):111-116
ABSTRACT: The techniques of conflict analysis derived from game theory were applied to the Shoal Lake water supply conflict in southeastern Manitoba, Canada. The issue of conflict is the desire of an Indian Band in the area to build cottage lots near the intake for water supply for the City of Winnipeg. The City of Winnipeg contends that such a development would seriously affect the quality of water supplied to the City, thereby increasing its treatment costs significantly. The four major players defined for the conflict are the City of Winnipeg, Indian Band No. 40, the Province of Manitoba, and the Federal Department of Indian and Northern Affairs. The results of the conflict analysis suggest that the introduction of the provincial and federal government into the conifict will not assist significantly in its resolution and that further progress on the resolution is unlikely until the results of Federal Environment Assessment Review office hearing become available. 相似文献
457.
458.
Dr Abdal‐Majeed I. Daghistani BA MSc PhD MRTPI 《Journal of Environmental Planning and Management》1991,34(1):2-9
The towns and cities of Saudi Arabia have been subjected to sustained growth pressures since the transformation of the country's economy following the discovery of oil in the Eastern Province of the Kingdom. The rapid growth which has been experienced has created major problems for the central and local government agencies responsible for planning and managing urban growth. The experience of Jeddah, one of the major cities in Saudi Arabia, is described and the problems of planning and managing its growth are analysed. Weaknesses relating to the structure of the planning system are identified, as are major difficulties in relation to the quality and quantity of professional staff. Recent attempts to improve the operation of the planning system are described and evaluated. 相似文献
459.
Soy isolate was treated with formaldehyde and glyoxal at 1.0, 2.5, and 5.0% (w/w isolate) and with adipic and acetic anhydrides. The materials were then compression-molded into plastic tensile bars and tested for tensile and yield strength, percentage elongation, Young's modulus, and water absorption. Treatment with 5% formaldehyde increased the tensile strength significantly, to 4.9 kg/mm2, compared with the untreated sample (3.7 kg/mm2). The yield strength increased slightly, to 0.68 kg/mm2. Elongation was significantly less after treatment with formaldehyde. Young's modulus increased after treatment and leveled off at 174 kg/mm2. Water absorption decreased as the formaldehyde concentration increased. Treatment with either glyoxal or adipic/acetic anhydride had a detrimental effect on the mechanical properties of the plastic specimens. Water absorption was decreased by glyoxal treatment but was not affected by adipic/acetic anhydride treatment. Long-fiber (lf), short-fiber (sf), and microcrystalline (mc) cellulose were incorporated into soy isolate at various levels. Cellulose addition decreased the percentage elongation and increased the rigidity of the plastic. All three cellulose additions increased Young's modulus. The tensile strength increased with the addition of sf-cellulose to soy isolate; lf-cellulose decreased the tensile strength, whereas the incorporation of mc-cellulose did not have a significant effect. The yield strength increased slightly with the addition of sf-cellulose and was less affected by the addition of lf- or mc-cellulose. All three types of cellulose slightly decreased water absorption at ca. 15% content.Journal Paper No. J-15563 of the Iowa Agriculture and Home Economics Experiment Station, Ames; Project No. 2863. 相似文献
460.