全文获取类型
收费全文 | 12508篇 |
免费 | 93篇 |
国内免费 | 67篇 |
专业分类
安全科学 | 235篇 |
废物处理 | 647篇 |
环保管理 | 991篇 |
综合类 | 1831篇 |
基础理论 | 2642篇 |
环境理论 | 7篇 |
污染及防治 | 3603篇 |
评价与监测 | 1106篇 |
社会与环境 | 1563篇 |
灾害及防治 | 43篇 |
出版年
2023年 | 83篇 |
2022年 | 241篇 |
2021年 | 258篇 |
2020年 | 119篇 |
2019年 | 145篇 |
2018年 | 333篇 |
2017年 | 306篇 |
2016年 | 456篇 |
2015年 | 276篇 |
2014年 | 524篇 |
2013年 | 1080篇 |
2012年 | 588篇 |
2011年 | 678篇 |
2010年 | 512篇 |
2009年 | 499篇 |
2008年 | 660篇 |
2007年 | 707篇 |
2006年 | 558篇 |
2005年 | 478篇 |
2004年 | 434篇 |
2003年 | 376篇 |
2002年 | 360篇 |
2001年 | 353篇 |
2000年 | 269篇 |
1999年 | 140篇 |
1998年 | 92篇 |
1997年 | 99篇 |
1996年 | 78篇 |
1995年 | 122篇 |
1994年 | 94篇 |
1993年 | 78篇 |
1992年 | 81篇 |
1991年 | 74篇 |
1990年 | 89篇 |
1989年 | 67篇 |
1988年 | 56篇 |
1987年 | 45篇 |
1986年 | 50篇 |
1985年 | 55篇 |
1984年 | 52篇 |
1983年 | 44篇 |
1982年 | 51篇 |
1981年 | 38篇 |
1980年 | 47篇 |
1979年 | 50篇 |
1972年 | 41篇 |
1964年 | 54篇 |
1959年 | 41篇 |
1958年 | 57篇 |
1956年 | 36篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
181.
A population of 1639 patients were seen for chorionic villus sampling (CVS). Embryonic death was identified at ultrasound in 5.3 per cent of patients. The number of patients undergoing CVS was 1551, with 1416 transcervical procedures and 135 transabdominal procedures. The most common indication for CVS was advanced maternal age. Spontaneous pregnancy losses identified by increased risk of pregnancy loss with increasing aspiration attempts. The total fetal loss for this population was 5.4 per cent with the pregnancy loss estimated due to procedure being 1.2 per cent. Analysis of placentae from patients having CVS and amniocen-tesis showed no differences. Microbiological assessment prior to CVS was similar to previous publications. 相似文献
182.
Dr. Mertin haben wir für seine Hilfe bei der Interpretation der elektronenmikroskopischen Aufnahmen, der Deutschen Forschungsgemeinschaft und dem Fonds der Chemischen Industrie für ihre finanzielle Unterstützung zu danken. 相似文献
183.
184.
185.
186.
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
187.
188.
189.
190.
Synthetic hydrophilic polymers find promising applications in pharmacology, biotechnology and chemistry. The biocompatibility, biodegradability and pharmacological activity of these polymers depend much on their hydrophilic nature. This article summarizes the recent developments in the utilization of the different classes of these hydrophilic polymers as pharmacologically active agents, for enzyme modification and as catalysts and supports for chemical reactions. 相似文献