全文获取类型
收费全文 | 1490篇 |
免费 | 33篇 |
国内免费 | 20篇 |
专业分类
安全科学 | 62篇 |
废物处理 | 78篇 |
环保管理 | 141篇 |
综合类 | 295篇 |
基础理论 | 262篇 |
环境理论 | 1篇 |
污染及防治 | 394篇 |
评价与监测 | 159篇 |
社会与环境 | 130篇 |
灾害及防治 | 21篇 |
出版年
2023年 | 11篇 |
2022年 | 25篇 |
2021年 | 32篇 |
2020年 | 20篇 |
2019年 | 23篇 |
2018年 | 48篇 |
2017年 | 55篇 |
2016年 | 60篇 |
2015年 | 48篇 |
2014年 | 67篇 |
2013年 | 108篇 |
2012年 | 54篇 |
2011年 | 93篇 |
2010年 | 67篇 |
2009年 | 73篇 |
2008年 | 82篇 |
2007年 | 74篇 |
2006年 | 57篇 |
2005年 | 57篇 |
2004年 | 66篇 |
2003年 | 72篇 |
2002年 | 53篇 |
2001年 | 56篇 |
2000年 | 33篇 |
1999年 | 28篇 |
1998年 | 16篇 |
1997年 | 14篇 |
1996年 | 5篇 |
1995年 | 14篇 |
1994年 | 12篇 |
1993年 | 17篇 |
1992年 | 17篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1976年 | 2篇 |
1970年 | 2篇 |
1962年 | 5篇 |
1961年 | 2篇 |
1938年 | 1篇 |
排序方式: 共有1543条查询结果,搜索用时 15 毫秒
631.
以滇池湿地景观设计为研究对象,介绍了水生植物在湿地景观设计中的作用和原则以及水生植物的选择、配置和生物浮岛技术的运用。 相似文献
632.
633.
634.
635.
In this investigation the original observation of a correlation between the concentration of amniotic fluid albumin and maternal serum alpha fetoprotein (AFP), as a proof for amniotic fluid-derived AFP in the maternal compartment is confirmed at 15 and 16 weeks of gestation. In contrast to the earlier reported highly significant relation in this study the correlation is only weak, especially at 15 weeks. This might be in agreement with a more frequent absence of raised maternal serum AFP levels in cases of raised amniotic fluid AFP levels prior to 16 weeks of gestation. Transamniotic AFP transport contributes a minor part of the AFP present in the maternal compartment, as also indicated by the lack of correlation between AFP concentrations in amniotic fluid and maternal serum. 相似文献
636.
Prenatal monitoring of three pregnancies at risk of Morquio's disease type A by determination of N-acetylgalactosamine 6-sulphate sulphatase activity in cultured amniotic cells is reported. In one pregnancy prenatal diagnosis of one affected fetus was made. Enzyme determinations in tissues of the aborted fetus confirmed the prenatal diagnosis. 相似文献
637.
针对外秦淮河的污染状况,采用挺水植物菖蒲和狭叶香蒲进行试验,对外秦淮河的污染水质进行净化;同时进行两种挺水植物在外秦淮河当前水质下的耐淹没性试验。通过试验研究得出,在深秋季节,虽然菖蒲和狭叶香蒲两种植物已经处于生长周期的最后阶段,但是对外秦淮河污染水质仍然有较好的净化效果,对TP、TN、氨氮等的去除率能达到80%以上,对CODMn的去除率偏低。而且通过净化和耐淹试验中两种植物的对比.菖蒲比狭叶香蒲更能适应外秦淮河的水质状况。 相似文献
638.
639.
运用层次分析法评价虎林市地表水环境质量 总被引:2,自引:0,他引:2
现代工业的发展,给环境带来了日趋严重的污染,也使得水环境质量变差.因此,对地表水环境质量的评价是一项重要内容.层次分析法(Analytic Hierarchy Process,简称AHP)是目前应用广泛的一种评价方法.文章采用层次分析法对虎林市地表水环境质量状况进行评价,并得出结论. 相似文献
640.
Dr D. H. Ledbetter J. M. Zachary J. L. Simpson M. S. Golbus E. Pergament L. Jackson M. J. Mahoney R. J. Desnick J. Schulman K. L. Copeland Y. Verlinsky T. Yang-Feng S. A. Schonberg A. Babu A. Tharapel A. Dorfmann H. A. Lubs G. G. Rhoads S. E. Fowler F. De La Cruz 《黑龙江环境通报》1992,12(5):317-345
Cytogenetic data are presented for 11 473 chorionic villus sampling (CVS) procedures from nine centres in the U.S. NICHD collaborative study. A successful cytogenetic diagnosis was obtained in 99.7 per cent of cases, with data obtained from the direct method only (26 per cent), culture method only (42 per cent), or a combination of both (32 per cent). A total of 1.1 per cent of patients had a second CVS or amniocentesis procedure for reasons related to the cytogenetic diagnostic procedure, including laboratory failures (27 cases), maternal cell contamination (4 cases), or mosaic or ambiguous cytogenetic results (98 cases). There were no diagnostic errors involving trisomies for chromosomes 21, 18, and 13. For sex chromosome aneuploidies, one patient terminated her pregnancy on the basis of non-mosaic 47,XXX in the direct method prior to the availability of results from cultured cells. Subsequent analysis of the CVS cultures and fetal tissues showed only normal female cells. Other false-positive predictions involving non-mosaic aneuploidies (n = 13) were observed in the direct or culture method, but these cases involved rare aneuploidies: four cases of tetraploidy, two cases of trisomy 7, and one case each of trisomies 3, 8, 11, 15, 16,20, and 22. This indicates that rare aneuploidies observed in the direct or culture method should be subjected to follow-up by amniocentesis. Two cases of unbalanced structural abnormalities detected in the direct method were not confirmed in cultured CVS or amniotic fluid. In addition, one structural rearrangement was misinterpreted as unbalanced from the direct method, leading to pregnancy termination prior to results from cultured cells showing a balanced, inherited translocation. False-negative results (n = 8) were observed only in the direct method, including one non-mosaic fetal abnormality (trisomy 18) detected by the culture method and seven cases of fetal mosaicism (all detected by the culture method). Mosaicism was observed in 0.8 per cent of all cases, while pseudomosaicism (including single trisomic cells) was observed in 1.6 per cent of cases. Mosaicism was observed with equal frequency in the direct and culture methods, but was confirmed as fetal mosaicism more often in cases from the culture method (24 per cent) than in cases from the direct method (10 per cent). The overall rate of maternal cell contamination was 1.8 per cent for the culture method, but there was only one case of incorrect sex prediction due to complete maternal cell contamination which resulted in the birth of a normal male. The rate of maternal cell contamination was significantly higher in samples obtained by the transcervical sampling method (2. 16 per cent) than in samples obtained by the transabdominal method (0.79 per cent). From these data, it is clear that the culture method has a higher degree of diagnostic accuracy than the direct method, which should not be used as the sole diagnostic technique. The direct method can be a useful adjunct to the culture method, in which maternal cell contamination can lead to incorrect sex prediction and potentially to false-negative diagnostic results. 相似文献