全文获取类型
收费全文 | 2487篇 |
免费 | 155篇 |
国内免费 | 255篇 |
专业分类
安全科学 | 187篇 |
废物处理 | 103篇 |
环保管理 | 1016篇 |
综合类 | 900篇 |
基础理论 | 294篇 |
污染及防治 | 116篇 |
评价与监测 | 106篇 |
社会与环境 | 110篇 |
灾害及防治 | 65篇 |
出版年
2024年 | 6篇 |
2023年 | 32篇 |
2022年 | 42篇 |
2021年 | 51篇 |
2020年 | 47篇 |
2019年 | 46篇 |
2018年 | 40篇 |
2017年 | 46篇 |
2016年 | 49篇 |
2015年 | 57篇 |
2014年 | 53篇 |
2013年 | 113篇 |
2012年 | 93篇 |
2011年 | 97篇 |
2010年 | 73篇 |
2009年 | 73篇 |
2008年 | 94篇 |
2007年 | 60篇 |
2006年 | 56篇 |
2005年 | 52篇 |
2004年 | 75篇 |
2003年 | 107篇 |
2002年 | 192篇 |
2001年 | 182篇 |
2000年 | 197篇 |
1999年 | 148篇 |
1998年 | 120篇 |
1997年 | 106篇 |
1996年 | 224篇 |
1995年 | 74篇 |
1994年 | 35篇 |
1993年 | 24篇 |
1992年 | 19篇 |
1991年 | 25篇 |
1990年 | 7篇 |
1989年 | 13篇 |
1988年 | 9篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 22篇 |
1984年 | 41篇 |
1983年 | 40篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1980年 | 9篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1971年 | 14篇 |
1967年 | 1篇 |
排序方式: 共有2897条查询结果,搜索用时 21 毫秒
41.
IntroductionMostofnitroaromaticsareimportantenvironmentalpollutants.ThecarpisthemajoreconomicfishinChinaandisoneofthefivestan?.. 相似文献
42.
The de-O-sulphation of α-linked glucosamine-6-sulphate residues in heparan sulphate requires a specific sulphatase, glucosamine-6-sulphatase, which has been shown to be deficient in tissues of Sanfilippo D, or mucopolysaccharidosis type IIID (MPS IIID), patients. MPS IIID fibroblasts cultured in Basal Eagle's medium supplemented with either fetal calf serum or heat-inactivated fetal calf serum, MDCB or Ultraserg media had residual glucosarnine-6-sulphatase activities towards a heparin-derived trisaccharide substrate, O-(α-N-acetylglucosamine-6-sulphate)-(1→4)-L -O-(α-iduronic acid-2-sulphate)-(1→4)-D -O-2,5-anhydro [1-3H]mannitol-6-sulphate, GlcNAc6S-IdoA2S-anM6S, which were less than 1 per cent of the normal range for fibroblasts cultured in Basal Eagle's medium supplemented with fetal calf serum. However, the glucosamine-6-sulphatase activities of MPS IIID fibroblasts grown in Chang's medium were similar to the activities in normal control fibroblasts which were cultured in Basal Eagle's medium. These results indicate that caution is required for prenatal diagnosis of MPS IIID patients using chorionic villi or amniotic cells cultured in Chang's medium. 相似文献
43.
Howard Cuckle Nicholas Wald Rossana Stone James Densem James Haddow George Knight 《黑龙江环境通报》1988,8(6):439-445
Thyroid antibodies were measured in mid-trimester antenatal serum samples from 77 pregnancies affected by fetal Down's syndrome and 385 unaffected control pregnancies. Using a haemagglutination technique, thyroglobulin antibodies were detected in 5·2 per cent of cases (4) and 2·9 per cent of controls (11), and thyroid microsomal antibodies were detected in 22 per cent (17) and 15 per cent (59), respectively. Using an enzyme-linked immunosorbent assay (ELISA) for thyroglobulin antibodies and a cut-off level of 50 KIU/1, positive results were found in 25 per cent of cases (19) and 22 per cent of controls (84). Using an ELISA for thyroid microsomal antibodies and the same cut-off level, the proportions were 52 per cent (40) and 39 per cent (149), respectively. While not statistically significant, the differences were consistent with the previously reported increased levels of thyroid antibody found in nonpregnant women who had had pregnancies associated with Down's syndrome. 相似文献
44.
Frances R. Sweetman Kenneth M. Gibson Lawrence Sweetman Ph.D William L. Nyhan Homer Chin William Swartz Oliver W. Jones 《黑龙江环境通报》1986,6(3):187-194
We have documented the presence of five mitochondrial enzymes in samples of chorionic villus tissue and measured the levels of activity. Three of the enzymes catalyse biotindependent reactions. These are propionyl-CoA carboxylase, 3-methylcrotonyl-CoA carboxylase and pyruvate carboxylase. the other enzymes. 4-aminobutyric acid aminotransferase and succinic semialdehyde dehydrogenase, are involved inthe degradation of the central inhibitory neurotransmitter GABA. Distinct diseases in whichthere is deficiency of each of these enzymes have been documented in man. Significant levels of activity were observed for all five enzymes in chorionic villus tissue. This methodology should permit early prenatal diagnosis of deficiencies of these enzymes by chorionic villus biopsy in the first trimester. 相似文献
45.
R. B. H. Schutgens G. Schrakamp R. J. A. Wanders H. S. A. Heymans H. W. Moser A. E. Moser J. M. Tagers H. V. D. Bosch P. Aubourm 《黑龙江环境通报》1985,5(5):337-344
Prenatal diagnosis of the cerebro-hepato-renal (Zellweger) syndrome has been performed in 10 pregnancies at risk by measuring both the activity of acyl CoA: dihydroxyacetonephosphate acyltransferase (DHAP-AT) and the de novo plasmalogen biosynthesis, either in cultured amniotic fluid cells or in fibroblasts cultured from a chorionic villus biopsy. In 7 of the pregnancies both tests indicated no abnormality. All 7 continued to term and normal infants were delivered. However, in amniotic fluid cells from 2 fetuses affected by Zellweger syndrome unequivocal differences from control values were found. The activity of DHAP-AT was clearly deficient and the de novo plasmalogen biosynthesis was impaired. In one pregnancy at risk prenatal diagnosis was performed during the first trimester by measuring both the DHAP-AT activity and the de novo plasmalogen biosynthesis in fibroblasts cultured from a chorionic villi biopsy. From the deficient DHAP-AT activity and the impaired de novo plasmalogen biosynthesis it was concluded that the fetus was affected. This was confirmed biochemically after induced abortion. It can be concluded that measurement of the DHAP-AT activity and the de novo plasmalogen biosynthesis provides convenient methods for the early prenatal detection of Zellweger syndrome. 相似文献
46.
三种固体废弃物综合利用的初步研究 总被引:6,自引:0,他引:6
从环境建设的可持续发展出发 ,结合天津开发区在基础设施及园林绿化建设中面临土源紧缺以及周边地区存在大量的海湾泥、粉煤灰、碱渣土等固体废弃物的现实 ,在详细研究了3种废物的物理、化学性质的基础上探讨了用这些废物代替农田客土的可行性。实验及推广应用结果表明 ,这些废物按适当比例混合后能够形成一种可替代种植客土的新型土壤 ,这种新型土壤的最佳配比(即海湾泥与粉煤灰或碱渣土 )比例为3:1 ,同时该配比基质对植物生长的适宜性优于滨海盐土。 相似文献
47.
SBR法运行控制工艺研究进展 总被引:3,自引:0,他引:3
SBR法是一种具有独特的优点的废水生物处理工艺,但至今还没有一套公认的运行控制工艺,本文从SBR法的启动,充水时间及反应时间的确定,模糊控制,目标控制操作等几方面对SBR工艺的运行控制做了评述,并对其今后的研究方向做了展望。 相似文献
48.
49.
广东沿岸海域生物可利用性重金属的地理分布 总被引:6,自引:3,他引:6
利用牡蛎做监测生物,研究了广东沿岸海域生物可利用性重金属Cd,Cu和Zn的地理分布。牡蛎体的Cd,Cu和Zn含量存在着显著的地域差异,反映了广东沿岸海域生物可利用性的Cd,Cu和Zn在地域上存在很大的梯度。由牡蛎显示出的广东沿岸海域生物可利用性重金属的地理分布与广东沿岸海域受人为来源的重金属输入状况相一致,如实地反映了广东沿岸海域重金属污染的基本特征。 相似文献
50.
本文研究了水深的变化以波高与周期联合概率密度分布造成影响。本文将236组实测数据按水深因子H的大小进行了分组,分别对其进行了谱分析和统计分析,得到了各组数据的联合分布图。利用数值模拟的方法扩大水深因子的变化幅度,得到了模拟联合分布图。研究发现,水深因子的改变不会对联合分布构成大的影响,因此得现一般水的波高与周期联合概率密度分布模式适用于浅海的结论。 相似文献