首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   14520篇
  免费   53篇
  国内免费   35篇
安全科学   113篇
废物处理   1098篇
环保管理   1599篇
综合类   1513篇
基础理论   4011篇
环境理论   6篇
污染及防治   3560篇
评价与监测   1480篇
社会与环境   1201篇
灾害及防治   27篇
  2023年   72篇
  2022年   201篇
  2021年   238篇
  2020年   104篇
  2019年   107篇
  2018年   1575篇
  2017年   1500篇
  2016年   1410篇
  2015年   300篇
  2014年   337篇
  2013年   534篇
  2012年   758篇
  2011年   1626篇
  2010年   932篇
  2009年   771篇
  2008年   1142篇
  2007年   1504篇
  2006年   246篇
  2005年   208篇
  2004年   179篇
  2003年   195篇
  2002年   220篇
  2001年   94篇
  2000年   65篇
  1999年   30篇
  1998年   26篇
  1997年   12篇
  1996年   17篇
  1995年   22篇
  1994年   18篇
  1993年   13篇
  1992年   9篇
  1991年   4篇
  1990年   8篇
  1988年   4篇
  1985年   5篇
  1984年   14篇
  1983年   11篇
  1982年   4篇
  1978年   5篇
  1967年   5篇
  1966年   4篇
  1965年   4篇
  1964年   7篇
  1963年   3篇
  1962年   5篇
  1959年   4篇
  1958年   15篇
  1957年   5篇
  1955年   3篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
61.
本文概述了莫桑比克包括渔业在内的海洋生物学研究的发展情况.莫桑比克的海岸线约为3000km,海洋的生物资源在莫桑比克的社会中起着重要的作用,主要是作为人们的蛋白质来源以及收入和出口创汇的来源.  相似文献   
62.
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   
63.
Egyptian Blue, a multicomponent synthetic blue pigment has been recorded in ancient Egypt since the Fourth Dynasty of the Old Kingdom (2600–2480 B.C.). The pigment consisting of cuprorivaite (CaCuSi4O10) with variable amounts of wollastonite (CaSiO3), Cu-rich glass and cuprite (Cu3O) or tenorite (CuO) was prepared by melting the copper-rich ingredient with lime and desert sand. Low melting temperatures (below 742 °C) were achieved by addition of flux-like plant ashes. The high quality of the pigments collected from monuments of the Fifth Dynasty (2480–2320 B.C.) may indicate that the first manufacture was in early dynastic or perhaps predynastic eras. During the reign of Thutmosis III (18th Dynasty, 1490–1436 B.C.) probably bronze filings were first applied as starting material, thus indicating a technological innovation. This new method was employed till the Roman times.  相似文献   
64.
65.
Female midwife toads (genus Alytes) emit highly variable reciprocal calls of unclear function prior to and during courtship. In some species, female-female competition, expressed as physical fighting, has been reported. Males of Majorcan midwife toads (Alytes muletensis) show phonotactic response to female calls, and females of Iberian midwife toads (Alytes cisternasii) respond differently according to the male call characteristics. In this study, I test the hypothesis of female-female acoustic competition as an additional function of female reciprocal calls. Playback tests indicate that female calls are not clearly involved in female acoustic competition in the Iberian midwife toad, therefore female calls could be directed at males rather than towards competitive females.  相似文献   
66.
67.
68.
69.
70.
An analysis of the impacts on Mexican energy demand and associated carbon dioxide (CO2) emissions in the year 2005 due to efficient lighting in the commercial and residential sectors and cogeneration in the industrial sector is presented. Estimation of CO2 abatement costs and an incremental cost curve for CO2 mitigation options are considered. These technologies are cost effective opportunities, and together are projected to reduce CO2 emissions in 2005 by nearly 13 percent. Implementation of efficient lighting is already part of the demand side management (DSM) programs of the Mexican state-owned utility. However, there are important barriers that may hinder the implementation of large scale cogeneration plants.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号