全文获取类型
收费全文 | 1273篇 |
免费 | 27篇 |
国内免费 | 9篇 |
专业分类
安全科学 | 51篇 |
废物处理 | 48篇 |
环保管理 | 324篇 |
综合类 | 143篇 |
基础理论 | 381篇 |
污染及防治 | 195篇 |
评价与监测 | 106篇 |
社会与环境 | 46篇 |
灾害及防治 | 15篇 |
出版年
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 22篇 |
2020年 | 14篇 |
2019年 | 16篇 |
2018年 | 25篇 |
2017年 | 28篇 |
2016年 | 43篇 |
2015年 | 31篇 |
2014年 | 29篇 |
2013年 | 76篇 |
2012年 | 72篇 |
2011年 | 72篇 |
2010年 | 53篇 |
2009年 | 45篇 |
2008年 | 59篇 |
2007年 | 68篇 |
2006年 | 76篇 |
2005年 | 52篇 |
2004年 | 48篇 |
2003年 | 56篇 |
2002年 | 37篇 |
2001年 | 19篇 |
2000年 | 27篇 |
1999年 | 19篇 |
1998年 | 23篇 |
1997年 | 24篇 |
1996年 | 22篇 |
1995年 | 18篇 |
1994年 | 13篇 |
1993年 | 15篇 |
1992年 | 16篇 |
1991年 | 8篇 |
1990年 | 13篇 |
1989年 | 9篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 7篇 |
1984年 | 14篇 |
1983年 | 11篇 |
1982年 | 11篇 |
1981年 | 16篇 |
1980年 | 6篇 |
1979年 | 12篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1959年 | 2篇 |
排序方式: 共有1309条查询结果,搜索用时 31 毫秒
11.
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
12.
13.
Stephen A. Wainwright 《Die Naturwissenschaften》1970,57(7):321-326
14.
R. Geiger 《Die Naturwissenschaften》1984,71(5):252-258
Peptide chemistry has reached a plateau on which more work is devoted to the improvement of known basic principles than to the development of really new methods. As a consequence, routine syntheses of peptides concentrate on few protecting groups and coupling procedures only. The recent progress in purification of peptides by liquid chromatography helped to promote this trend. Meanwhile, recombinant technology permits the synthesis of proteins and possibly of some lower peptides, too. It cannot compete, however, with chemical solid-phase synthesis of a newly discovered peptide with up to about 40 amino acids in speed but may take over the synthesis for large-scale production. Peptides containing modified or non-natural structures, which are often superior to the natural compounds as drugs, will remain subject of chemical synthesis, too. Present research focuses on the role of peptide and protein factors in the immune response and on structure and biological activities of neuropeptides. 相似文献
15.
16.
17.
Dr. Linda A. Cannizzaro Barbara K. Hecht Helen A. Bixenman Stephen Pazdziorko Robert Tamis Frederick Hecht 《黑龙江环境通报》1988,8(4):297-301
We report herein a de novo unbalanced chromosome translocation in a fetus resulting from in vitro fertilization technology. Prenatal diagnostic analysis of an amniotic fluid revealed a 46,XX,4p+ karyotype. The origin of the extra material on the short arm of chromosome 4 could not be identified by a variety of banding techniques. However, examination of fetal parts did reveal some dysmorphic features. 相似文献
18.
In a retrospective survey, the incidence of neural tube defects in liveborn trimsomy 18 was found to be 6·2 per cent. Based on these data one would expect to find trisomy 18 in 1 of the 117 patients with myeloidysplasia; the incidence of trisomy 18 in dysraphic fetuses would be anticipated to be higher. These observations underscore the need for amniocentesis karyotyping of fetuses with neural tube defects, and the importance of careful examination of infants born with neural tube defects. 相似文献
19.
Dr. O. W. Jones Nolan E. Penn Stephen Shuchter Claire A. Stafford Teri Richards Colleen Kernahan Jennifer Gutierrez Patricia Cherkin Sylvia Reinsch Barbara Dixson 《黑龙江环境通报》1984,4(4):249-256
This article reports the results of a retrospective study designed to examine the responses of couples to genetic amniocentesis and subsequent therapeutic abortions due to birth defects. Fourteen women and 12 men were interviewed by experienced interviewers using a structured format designed by the authors, and each interview was audiotaped for later rating. The 5 raters (all women) were instructed to independently rate each interview using forms designed by the authors to elicit information about many aspects of the participant's individual responses as well as perceptions of spouse's responses to the process of pregnancy, amniocentesis, therapeutic abortion, and sequelae. Ratings of all 5 raters were conjoined and an homogeneous narrative was constructed for each interview. Results indicate, in general, that the respondent couples coped well with this experience. In fact 70 per cent of the respondent couples described their marital relationships as becoming closer as a result of their experience. Only a few participants reported long-term deleterious effects. Most couples coped by relying on relatives, friends, and occasionally, professional counsellors. In addition, most participants in this study suggested ways to improve the medical and psychological aspects of this experience. 相似文献
20.