全文获取类型
收费全文 | 26161篇 |
免费 | 570篇 |
国内免费 | 3150篇 |
专业分类
安全科学 | 1067篇 |
废物处理 | 1220篇 |
环保管理 | 3037篇 |
综合类 | 7338篇 |
基础理论 | 6193篇 |
环境理论 | 5篇 |
污染及防治 | 7807篇 |
评价与监测 | 1446篇 |
社会与环境 | 1307篇 |
灾害及防治 | 461篇 |
出版年
2023年 | 234篇 |
2022年 | 587篇 |
2021年 | 511篇 |
2020年 | 394篇 |
2019年 | 446篇 |
2018年 | 560篇 |
2017年 | 615篇 |
2016年 | 774篇 |
2015年 | 696篇 |
2014年 | 1027篇 |
2013年 | 2234篇 |
2012年 | 1187篇 |
2011年 | 1423篇 |
2010年 | 1160篇 |
2009年 | 1088篇 |
2008年 | 1362篇 |
2007年 | 1222篇 |
2006年 | 1179篇 |
2005年 | 881篇 |
2004年 | 911篇 |
2003年 | 888篇 |
2002年 | 817篇 |
2001年 | 1003篇 |
2000年 | 770篇 |
1999年 | 584篇 |
1998年 | 481篇 |
1997年 | 448篇 |
1996年 | 422篇 |
1995年 | 415篇 |
1994年 | 389篇 |
1993年 | 344篇 |
1992年 | 367篇 |
1991年 | 311篇 |
1990年 | 298篇 |
1989年 | 280篇 |
1988年 | 223篇 |
1987年 | 194篇 |
1986年 | 175篇 |
1985年 | 185篇 |
1984年 | 206篇 |
1983年 | 191篇 |
1982年 | 198篇 |
1981年 | 189篇 |
1980年 | 142篇 |
1979年 | 158篇 |
1978年 | 134篇 |
1977年 | 118篇 |
1975年 | 122篇 |
1974年 | 121篇 |
1972年 | 147篇 |
排序方式: 共有10000条查询结果,搜索用时 468 毫秒
601.
J. G. Hooker M. Lucas B. A. Richards I. M. Shirley B. D. Thompson R. H. T. Ward 《黑龙江环境通报》1984,4(1):29-33
Estimation of maternal serum alpha-fetoprotein (AFP) was used as a screening method for the detection of neural tube defects (NTDs) in 6344 women over three years. Of 88 (1.4 per cent) who had one or more serum AFP levels equal to, or greater than, 2.5 multiples of the median (MoM) for the relevant gestational age, 43 (0.68 per cent) underwent amniocentesis. There were eight NTDs. Four of these were screened by serum AFP, and all cases of spina bifida had serum AFP levels greater than 3.0 MoM, including one small open defect which was not seen on ultrasound. The other four cases of NTD, which were not screened, were identified by ultrasound. Of 64 singleton pregnancies 32 (50 per cent) had serum AFP levels between 2.5 and 3.0 MoM, and low birthweight (⪕2500 g) occurred in 29 per cent. Because of improvements in ultrasound techniques and the apparent falling incidence of NTD, the role of serum AFP as the primary screening procedure should be regularly reviewed. Effective screening is dependent on mothers booking early. 相似文献
602.
Routine ultrasound examination at 30 weeks gestation revealed an intrapulmonary cystic mass in an otherwise normal fetus. Following delivery at term, the diagnosis of congenital cystic adenomatoid malformation of the right lung was confirmed, and an elective right middle lobectomy successfully performed at nine days of age. 相似文献
603.
Postpartum women ≧ 33 years were interviewed about their attitudes to and knowledge and use of prenatal diagnosis. Overall, 68 per cent had heard of prenatal diagnosis; nevertheless, only 30 per cent of those ≧ 35 had actually been tested. The only significant difference between eligible women who were tested and those who were not was maternal age. Of those tested, half requested it for themselves; conversely, only two-thirds of women requesting the procedure actually received it. Among women not tested, 82 per cent were never offered the procedure by the physician. Expressed attitudes to prenatal diagnosis were strongly positive among all women, with 75 per cent continuing to want testing after learning both their age-specific risk of having an affected child and the possible risks of amniocentesis. The data document a potential demand for amniocentesis far in excess of current use and present service facilities. They suggest, moreover, that underuse may reflect professional hesitation and underreferral more than consumer lack of demand or reluctance to be tested. 相似文献
604.
605.
606.
607.
南京市城市生活垃圾分类收集问卷调查 总被引:6,自引:0,他引:6
围绕南京市城市生活垃圾分类收集的问卷调查展开,揭示了南京市生活垃圾收集开展的现状,分析了其间存在的问题及成因,提出了相应的改进意见和解决办法,为生活垃圾分类收集在全国的推广提供了依据。 相似文献
608.
Environmental managers at U.S. Department of Defense (DoD) installations overseas are faced with the challenge of managing contaminated sites at these installations with little information on the extent of contamination or the risk posed by the site. In this regard, DoD managers overseas encounter a situation quite similar to the situation faced by decision makers in the U.S. who are managing brownfields. Innovative site characterization and risk-based decision-making methods, which are currently being developed for expeditious application at brownfield sites in the U.S., may also be appropriate for application at overseas DoD sites. In this paper, the analytic hierarchy process (AHP) is used by DoD decision makers to evaluate and rank innovative site characterization technologies and risk-based decision-making and management methods, for use at installations in Korea. Results indicate that for sites with high potential risk the decision makers preferred site characterization technologies that produce data of high quality and a method that can be used to establish credible risk-based remediation goals. This study provides a framework for applying characterization technologies and risk management to poorly characterized contaminated sites in developing countries, where resources for remedial actions may be limited. 相似文献
609.
610.