全文获取类型
收费全文 | 30718篇 |
免费 | 475篇 |
国内免费 | 1135篇 |
专业分类
安全科学 | 993篇 |
废物处理 | 1376篇 |
环保管理 | 3909篇 |
综合类 | 5869篇 |
基础理论 | 8336篇 |
环境理论 | 12篇 |
污染及防治 | 8067篇 |
评价与监测 | 1963篇 |
社会与环境 | 1536篇 |
灾害及防治 | 267篇 |
出版年
2022年 | 352篇 |
2021年 | 344篇 |
2020年 | 281篇 |
2019年 | 291篇 |
2018年 | 476篇 |
2017年 | 501篇 |
2016年 | 685篇 |
2015年 | 590篇 |
2014年 | 848篇 |
2013年 | 2405篇 |
2012年 | 1031篇 |
2011年 | 1367篇 |
2010年 | 1112篇 |
2009年 | 1116篇 |
2008年 | 1374篇 |
2007年 | 1368篇 |
2006年 | 1250篇 |
2005年 | 1023篇 |
2004年 | 958篇 |
2003年 | 1011篇 |
2002年 | 944篇 |
2001年 | 1226篇 |
2000年 | 882篇 |
1999年 | 532篇 |
1998年 | 408篇 |
1997年 | 419篇 |
1996年 | 444篇 |
1995年 | 500篇 |
1994年 | 435篇 |
1993年 | 373篇 |
1992年 | 390篇 |
1991年 | 381篇 |
1990年 | 400篇 |
1989年 | 377篇 |
1988年 | 332篇 |
1987年 | 312篇 |
1986年 | 272篇 |
1985年 | 281篇 |
1984年 | 324篇 |
1983年 | 282篇 |
1982年 | 337篇 |
1981年 | 278篇 |
1980年 | 233篇 |
1979年 | 257篇 |
1978年 | 218篇 |
1977年 | 190篇 |
1975年 | 187篇 |
1974年 | 200篇 |
1973年 | 197篇 |
1972年 | 180篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
241.
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
242.
243.
244.
245.
246.
Gulzar Kassam Andrew T. L. Chen Marshall F. Goldberg Suzanne Trusler Godfrey P. Oakley Jr. 《黑龙江环境通报》1984,4(3):213-216
Although prenatal genetic diagnosis can usually provide prospective parents with information as to whether their fetus is affected with certain genetic conditions, the presence of twins and the uncertainty about the phenotype of some chromosome variations pose a major dilemma and make genetic counselling very difficult. Here, a case report of an unusual chromosome aberration (pericentric inversion of chromosome no. 17) in a twin pregnancy which was originally suspected to be monoamniotic but later proved to have two sacs was presented. 相似文献
247.
248.
Social insects use complex chemical communication systems to govern many aspects of their life. We studied chemical changes in Dufours gland secretions associated with ovary development in several genotypes of honeybees. We found that C28–C38 esters were associated only with cavity nesting honeybee queens, while the alcohol eicosenol was associated only with their non-laying workers. In contrast, both egg-laying anarchistic workers and all parasitic Cape workers from queenright colonies showed the typical queen pattern (i.e. esters present and eicosenol absent), while egg-laying wild-type and anarchistic workers in queenless colonies showed an intermediate pattern, producing both esters and eicosenol but at intermediate levels. Furthermore, neither esters nor eicosenol were found in aerial nesting honeybee species. Both esters and eicosenol are biosynthetically similar compounds since both are recognizable products of fatty acid biosynthesis. Therefore, we propose that in honeybees the biosynthesis of esters and eicosenol in the Dufours gland is caste-regulated and this pathway has been conserved over evolutionary time. 相似文献
249.
E. A. Loupian A. A. Mazurov E. V. Flitman D. V. Ershov G. N. Korovin V. P. Novik N. A. Abushenko D. A. Altyntsev V. V. Koshelev S. A. Tashchilin A. V. Tatarnikov I. Csiszar A. I. Sukhinin E. I. Ponomarev S. V. Afonin V. V. Belov G. G. Matvienko T. Loboda 《Mitigation and Adaptation Strategies for Global Change》2006,11(1):113-145
250.