全文获取类型
收费全文 | 9684篇 |
免费 | 810篇 |
国内免费 | 1203篇 |
专业分类
安全科学 | 2332篇 |
废物处理 | 273篇 |
环保管理 | 1586篇 |
综合类 | 4553篇 |
基础理论 | 819篇 |
环境理论 | 4篇 |
污染及防治 | 572篇 |
评价与监测 | 465篇 |
社会与环境 | 626篇 |
灾害及防治 | 467篇 |
出版年
2024年 | 15篇 |
2023年 | 95篇 |
2022年 | 187篇 |
2021年 | 282篇 |
2020年 | 320篇 |
2019年 | 265篇 |
2018年 | 205篇 |
2017年 | 317篇 |
2016年 | 383篇 |
2015年 | 353篇 |
2014年 | 429篇 |
2013年 | 591篇 |
2012年 | 771篇 |
2011年 | 780篇 |
2010年 | 578篇 |
2009年 | 658篇 |
2008年 | 435篇 |
2007年 | 671篇 |
2006年 | 631篇 |
2005年 | 535篇 |
2004年 | 485篇 |
2003年 | 446篇 |
2002年 | 420篇 |
2001年 | 273篇 |
2000年 | 300篇 |
1999年 | 253篇 |
1998年 | 177篇 |
1997年 | 189篇 |
1996年 | 126篇 |
1995年 | 147篇 |
1994年 | 104篇 |
1993年 | 68篇 |
1992年 | 66篇 |
1991年 | 32篇 |
1990年 | 20篇 |
1989年 | 15篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1982年 | 6篇 |
1980年 | 4篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1970年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Supplementing the nutrient requirement of crops through organic manures plays a key role in sustaining soil fertility, and crop productivity and reducing use of fossil fuels. Field experiments were conducted for 2 years at two different locations (i.e. Lucknow and Pantnagar) in Uttar Pradesh, India. The objectives of the study were to assess the herb and essential oil yields of Japanese mint (Mentha arvensis cv. Hy 77), and its nutrient accumulation under single and combined applications of organic manures and inorganic fertilizers (NPK). Changes in physical and chemical characteristics of the soils (Fluvisols, Mollisols) were also determined. Eight treatments comprising different combinations of NPK through inorganic fertilizers and farm yard manure (FYM) were compared. The distilled waste of mint after extraction of essential oil was recycled to soils in the plots to supplement the nutritional requirement of the succeeding mustard crop (Brassica juncea cv. Pusa Bold). Herb and essential oil yield of mint were significantly higher with combined application of organic and inorganic sources of nutrients as compared to single applications. Accumulation of N and P was at par under full inorganic and combined supply whereas, K accumulation was higher with the former. Soil organic C and pH after harvest of mint did not significantly differ among the treatments, but the level of mineralizable N, Olsen-P and NH4OAc extractable K were higher in soil with integrated supply of nutrients. Significant increase in soil water stable aggregates, organic C, available NPK and microbial biomass, and decrease in soil bulk density were observed with waste recycling over fertilizer application. These benefits were reflected in the seed and stubble yield of mustard which succeeded mint. This study indicates that combined application of inorganic fertilizers with organics helps in increasing the availability of nutrients and crop yield and provides a significant effect to the succeeding crop. Similarly, recycling crop residues reduces the need for fossil fuel based fertilizer, and helps in sustaining and restoring soil fertility in terms of available nutrients and major physical and chemical characteristics of the soil. 相似文献
63.
64.
无盘网络系统是一种很适合在计算机配置较固定、软件程序较划一的网络环境中运行的网络系统,随着电脑教育的规模扩大,网络教室的普及,发展也非常快.本文简述了其产生环境、功能介绍,针对其优势和不足说明了无盘网络系统的应用前景是非常广阔的. 相似文献
65.
笔者从我国包装的现状分析入手,探讨建立绿色包装系统的可行性和必要性,提出建立绿色包装系统的具体措施和实施方案。 相似文献
66.
ISO14000与煤炭企业的可持续发展 总被引:1,自引:0,他引:1
本文结合煤炭企业的自身特点,论述了在煤炭企业开发ISO14000环境标准的重大意义和如何开发和实施ISO14000。此外,还就存在的问题提出了解决办法,以实现煤炭企业的可持续发展。 相似文献
67.
68.
TechnologicalsystemforsustainabledevelopmentofChineseagricultureZhangRenwu;JiWenying;ZhangTong(Agro-EnvironmentalProtectionIn... 相似文献
69.
REMIS is one of key research projects sponsored by the central government. It is recommended to regional EPAs as a main tool of the environmental management. REMIS simulates the functions of the regional EPAs and aimed to improve their management level. The national environmental management information system will base on REMIS.Functional analysis is the kernel of the REMIS system analysis. Data and data flow analysis are used to support the functional analysis.Investigations on the functions of the local EPAs of eight provinces and 12 cities have been taken. The functions were carefully sorted. Modular design method was used in system analysis and system design.The system analysis included functional analysis, data analysis and data flow analysis. The system design is based on the system analysis. HIPO diagram of each modular, data base structure, menu design, selection of hardware and software environment were the main items of the system design. 相似文献
70.