全文获取类型
收费全文 | 9790篇 |
免费 | 595篇 |
国内免费 | 635篇 |
专业分类
安全科学 | 1188篇 |
废物处理 | 244篇 |
环保管理 | 2526篇 |
综合类 | 3773篇 |
基础理论 | 941篇 |
环境理论 | 4篇 |
污染及防治 | 291篇 |
评价与监测 | 211篇 |
社会与环境 | 1651篇 |
灾害及防治 | 191篇 |
出版年
2024年 | 7篇 |
2023年 | 61篇 |
2022年 | 173篇 |
2021年 | 204篇 |
2020年 | 196篇 |
2019年 | 195篇 |
2018年 | 173篇 |
2017年 | 282篇 |
2016年 | 281篇 |
2015年 | 260篇 |
2014年 | 329篇 |
2013年 | 615篇 |
2012年 | 613篇 |
2011年 | 675篇 |
2010年 | 464篇 |
2009年 | 479篇 |
2008年 | 388篇 |
2007年 | 636篇 |
2006年 | 604篇 |
2005年 | 512篇 |
2004年 | 473篇 |
2003年 | 470篇 |
2002年 | 448篇 |
2001年 | 379篇 |
2000年 | 412篇 |
1999年 | 339篇 |
1998年 | 239篇 |
1997年 | 203篇 |
1996年 | 166篇 |
1995年 | 142篇 |
1994年 | 125篇 |
1993年 | 117篇 |
1992年 | 70篇 |
1991年 | 41篇 |
1990年 | 38篇 |
1989年 | 15篇 |
1988年 | 14篇 |
1987年 | 13篇 |
1986年 | 21篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 18篇 |
1981年 | 7篇 |
1980年 | 15篇 |
1979年 | 20篇 |
1978年 | 14篇 |
1977年 | 10篇 |
1973年 | 10篇 |
1971年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
20世纪80年代以来挠力河流域湿地景观变化过程研究 总被引:59,自引:6,他引:59
挠力河流域面积为241.67×104hm2。其自然条件决定了该流域具有极丰富的湿地生物多样性。从1980年以来,由于经济的快速发展,该流域湿地景观和土地利用发生了显著的变化。自然湿地资源从1982年的53.32×104hm2变成2000年的17.17×104hm2,减少了67.8%;而水田面积却增加了38.5倍,同时,旱田面积也大幅度增加。该文利用遥感和GIS技术,对近20年来该流域湿地景观变化过程进行时空定量分析;并结合流域土地利用/土地覆盖类型的动态变化,探讨流域在经济快速发展中土地利用与湿地之间的演化规律及其对湿地的影响机制。 相似文献
132.
133.
Can Forest-protection carbon projects improve rural livelihoods? Analysis of the Noel Kempff Mercado climate action project,Bolivia 总被引:1,自引:0,他引:1
Asquith Nigel M. Vargas Ríos María Teresa Smith Joyotee 《Mitigation and Adaptation Strategies for Global Change》2002,7(4):323-337
We studied the Noel KempffMercado Climate Action Project (NKMCAP),Bolivia, to assess whether forestprotection carbon (C) projects cansignificantly benefit local people. Wehypothesized that forest protection canonly securely deliver C if significantstakeholders are meaningfully andtransparently involved, traditional orcustomary rights are recognized and theirloss compensated for, and there are directlinkages between conservation anddevelopment objective. Our researchfocused on 53 members of the communities ofFlorida, Porvenir and Piso Firme and 36secondary stakeholders. In each of thevillages we held half-day meetings withcommunity leaders, complemented bysemi-structured one-hour interviews with 5,10, and 7 families, representing 20%, 10%and 8% of each community. The long-termimpact of the NKMCAP on the localcommunities may well be positive. However,in the short run, certain sections of thelocal communities are financially poorer. Forest protection projects clearly have thepotential to sequester C, protectbiodiversity and simultaneously contributeto sustainable rural development, but ifthey really are to improve rurallivelihoods, they must be designed andimplemented carefully and participatively. 相似文献
134.
柴宁 《辽宁城乡环境科技》2002,22(2):1-3
文中提及我国现阶段节水工作要从提高新水资源利用率入手,在进行节水宣传教育的同时,建立能动的节水机制,充分利用宝贵的降水资源,发挥可利用新水资源最大的效率,为我国未来经济社会的发展创造有利的条件。 相似文献
135.
136.
137.
西部大开发与内河水运可持续发展浅析 总被引:1,自引:0,他引:1
结合国家西部大开发的发展战略和西部生态环境特点,分析了西部内河水运可持续发展问题的特点,从建立健全环境管理体系、开展系统性的科研与教育工作、建立完善法规和标准体系等几个方面浅析了建立和完善内河水运可持续发展体系的必要性和关键内容。 相似文献
138.
上海生活垃圾资源化产业的发展探讨 总被引:6,自引:0,他引:6
概述了国内外生活垃圾资源化利用的现状,对上海生活垃圾资源化利用状况和问题作了分析,探讨了垃圾资源化利用的价值和实现途径,提出了促进上海生活垃圾资源化产业发展的几点建设。 相似文献
139.
浅析我国水资源与水污染治理现状 总被引:18,自引:0,他引:18
从我国水资源的贫乏,部分地区水资源的浪费和主要水流域污染的日益加剧等方面描述了我国水资源的现状,对水污染的治理提出了对付策略. 相似文献
140.
N. Sanginga K. E. Dashiell J. Diels B. Vanlauwe O. Lyasse R. J. Carsky S. Tarawali B. Asafo-Adjei A. Menkir S. Schulz B. B. Singh D. Chikoye D. Keatinge R. Ortiz 《Agriculture, ecosystems & environment》2003,100(2-3):305
Sustainable resource management is the critical agricultural research and development challenge in sub-Saharan Africa. The accumulated knowledge on soil management gathered over the last 10 years, combined with solid crop improvement and plant health research at farmers’ level, has brought us to a stage where we can now address with confidence the intensification of cereal–grain–legume-based cropping systems in the dry savanna of West Africa in a sustainable and environmentally positive manner.Two sustainable farming systems that greatly enhance the productivity and sustainability of integrated livestock systems have been developed and implemented in the dry savanna of Nigeria. These are: (i) maize (Zea mays L.)–promiscuous soybean [Glycine max (L.) Merr.] rotations that combine high nitrogen fixation and the ability to kill large numbers of Striga hermonthica seeds in the soil; and (ii) miflet [Eleusine coracana (L.) Gaerth] and dual-purpose cowpea [Vigna unguiculata (L.) Walp.]. Improvement of the cropping systems in the dry savanna has been driven by the adoption of promiscuously nodulating soybean varieties (in particular TGx 1448-2E) and dual-purpose cowpea. The rate of adoption is very high, even in the absence of an efficient seed distribution system. The number of farmers cultivating the improved varieties increased by 228% during the last 3 years. Increased production of promiscuous soybean has been stimulated by increased demand from industries and home utilization. Production in Nigeria was estimated at 405,000 t in 1999 compared to less than 60,000 t in 1984. Economic analysis of these systems shows already an increase of 50–70% in the gross incomes of adopting farmers compared to those still following the current practices, mainly continuous maize cultivation. Furthermore, increases in legume areas of 10% in Nigeria (about 30,000 ha in the northern Guinea savanna) and increases of 20% in yield have translated into additional fixed nitrogen valued annually at US$ 44 million. This reflects, at the same time, an equivalent increase in land-use productivity, and with further spread of the improved crops, there are excellent prospects for additional economic and environmental benefits from a very large recommendation domain across West Africa. 相似文献