全文获取类型
收费全文 | 405篇 |
免费 | 50篇 |
国内免费 | 13篇 |
专业分类
安全科学 | 168篇 |
废物处理 | 1篇 |
环保管理 | 60篇 |
综合类 | 146篇 |
基础理论 | 30篇 |
污染及防治 | 15篇 |
评价与监测 | 22篇 |
社会与环境 | 12篇 |
灾害及防治 | 14篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 9篇 |
2021年 | 12篇 |
2020年 | 6篇 |
2019年 | 14篇 |
2018年 | 16篇 |
2017年 | 14篇 |
2016年 | 15篇 |
2015年 | 20篇 |
2014年 | 18篇 |
2013年 | 18篇 |
2012年 | 28篇 |
2011年 | 41篇 |
2010年 | 22篇 |
2009年 | 18篇 |
2008年 | 20篇 |
2007年 | 21篇 |
2006年 | 24篇 |
2005年 | 26篇 |
2004年 | 15篇 |
2003年 | 16篇 |
2002年 | 15篇 |
2001年 | 9篇 |
2000年 | 8篇 |
1999年 | 9篇 |
1998年 | 9篇 |
1997年 | 7篇 |
1996年 | 10篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 3篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有468条查询结果,搜索用时 299 毫秒
111.
R. K. Sampath 《Journal of the American Water Resources Association》1991,27(5):745-751
ABSTRACT: This paper critically evaluates the nature of irrigation distribution in India using the Rawlsian criterion of equity in dis. tribution and estimates the performance of different states in India according to the Rawlsian notion of fairness in distribution. It is found that there is considerable inequality across farm-size groups in the distribution of irrigated areas in general and canal irrigated areas in particular, and that there are wide interstate differences in the levels of this inequality. Further, it is found that switching over to a Rawlsian based distribution of canal irrigation will help in reducing the levels of inequality in overall irrigation distribution in all states. 相似文献
112.
对环境监测布点采样中的QC/QA以及由采样引起的误差来源做了简要分析,并对监测采样过程中QC/QA的操作提出了一些设想。 相似文献
113.
114.
依据声级测量的误差分析,结合实例,对国家现行《超标环境噪声排污费征收标准》提出异议,建议取消1dB(A)的超标收费规定、舍弃测量的小数值,并定义一个考虑污染范围的评价量以使收费更加合理。 相似文献
115.
经过对PH玻璃电极对比观测实验,总结其在日常观测中衰减变化规律,以及PH电极失效前所具有的特征;讨论了对现有PH观测数据进行修正的方法,并编著相关修正程序;分析日常存在的测量误差,提出提高观测精度的措施。 相似文献
116.
针对计算机类学生在软件编程中出现的问题,本文就格式化编码、界面设计的一致性和清晰性、错误报告的方式与时机、交互二重性等方面进行了细致的介绍,以Visual Basic 6.x为编程语言提出了相应的解决办法,对提高计算机类专业学生的编程素质有较强的指导意义,对其他软件开发或程序设计人员也有较高的借鉴价值。 相似文献
117.
118.
119.
BACKGROUND: Taiwan's geography and limited stock of sandstone have caused sandstone resources to gradually decline to the point of exhaustion after long-term excavation. Moreover, the Taiwanese government has continuously increased the amount of land area near rivers that cannot be excavated to facilitate riverbed remediation and promote conservation of water resources. Accordingly, predicting and managing the annual production of construction aggregates in future construction projects, and dealing appropriately with some thorny problems, for instance, demand that excess supply, excessive excavation, unregulated excavation, and the consequent environmental damage, will significantly affect the efficient use of natural resources in a manner that accords with the national policy of Sustainable Development (SD). METHODS:. This study establishes an empirical model for forecasting the annual production of future construction aggregates using Artificial Neural Networks (ANN), based on 15 relevant socio-economic indicators, such as indicator of annual consumption of cement. A sensitivity analysis is then performed on these indicators. RESULTS AND DISCUSSION: This work applies ANN to estimate the annual production of construction aggregates; the estimates, the verification of the model and the sensitivity analysis are all acceptable. Furthermore, sensitivity analysis results indicate that the annual consumption of cement is the indicator that most strongly influences the production of construction aggregates, as well as whether construction waste can be recycled and steel structures can be used in buildings, helping to reduce the future production of construction aggregates in Taiwan. CONCLUSIONS: The elaborate prediction methodology presented in this study avoids some of the weaknesses or limitations of conventional linear statistics, linear programming or system dynamics. Additionally, the results not only provide a short-term prediction of the production of construction aggregates in Taiwan, but also provide a viable and flexible means of verifying quality certification of the production data of construction aggregates in the future by incorporating those relevant socio-economic indicators. RECOMMENDATIONS AND OUTLOOK: The continuity and quality of the database of relevant indicators used in this study should be closely scrutinized in order to ensure the SD means of exploiting resources. 相似文献
120.
In many environmental studies measuring the amount of a contaminant in a sampling unit is expensive. In such cases, composite sampling is often used to reduce data collection cost. However, composite sampling is known to be beneficial for estimating the mean of a population, but not necessarily for estimating the variance or other parameters. As some applications, for example, Monte Carlo risk assessment, require an estimate of the entire distribution, and as the lognormal model is commonly used in environmental risk assessment, in this paper we investigate efficiency of composite sampling for estimating a lognormal distribution. In particular, we examine the magnitude of savings in the number of measurements over simple random sampling, and the nature of its dependence on composite size and the parameters of the distribution utilizing simulation and asymptotic calculations. 相似文献