全文获取类型
收费全文 | 23477篇 |
免费 | 240篇 |
国内免费 | 197篇 |
专业分类
安全科学 | 666篇 |
废物处理 | 746篇 |
环保管理 | 3413篇 |
综合类 | 5103篇 |
基础理论 | 5858篇 |
环境理论 | 13篇 |
污染及防治 | 5797篇 |
评价与监测 | 1246篇 |
社会与环境 | 928篇 |
灾害及防治 | 144篇 |
出版年
2021年 | 155篇 |
2019年 | 158篇 |
2018年 | 267篇 |
2017年 | 259篇 |
2016年 | 394篇 |
2015年 | 331篇 |
2014年 | 441篇 |
2013年 | 1739篇 |
2012年 | 630篇 |
2011年 | 888篇 |
2010年 | 681篇 |
2009年 | 837篇 |
2008年 | 900篇 |
2007年 | 931篇 |
2006年 | 840篇 |
2005年 | 690篇 |
2004年 | 646篇 |
2003年 | 693篇 |
2002年 | 638篇 |
2001年 | 874篇 |
2000年 | 620篇 |
1999年 | 405篇 |
1998年 | 274篇 |
1997年 | 282篇 |
1996年 | 314篇 |
1995年 | 346篇 |
1994年 | 362篇 |
1993年 | 313篇 |
1992年 | 296篇 |
1991年 | 330篇 |
1990年 | 344篇 |
1989年 | 324篇 |
1988年 | 267篇 |
1987年 | 264篇 |
1986年 | 258篇 |
1985年 | 248篇 |
1984年 | 240篇 |
1983年 | 258篇 |
1982年 | 257篇 |
1981年 | 251篇 |
1980年 | 228篇 |
1979年 | 237篇 |
1978年 | 197篇 |
1977年 | 191篇 |
1976年 | 182篇 |
1975年 | 172篇 |
1974年 | 189篇 |
1973年 | 180篇 |
1972年 | 178篇 |
1967年 | 170篇 |
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
351.
C. A. Dell'Agnola V. Tomaselli E. Teruzzi B. Tadini A. G. Coran Surgeon-in-Chief 《黑龙江环境通报》1993,13(7):629-632
The impact of prenatal sonographic diagnosis of oesophageal and gastrointestinal obstructions has been analysed over a 10-year period. Three groups of patients were evaluated. The first group consisted of 46 newborns with abnormal prenatal sonogratns, 41 of which were confirmed to have intestinal obstruction postnatally. The second group consisted of 17 neonates with normal prenatal sonograms who had intestinal obstruction postnatally. The third group included 56 newborns who did not undergo a prenatal sonogram but who had intestinal obstruction confirmed at surgery. Polyhydramnios without the appearance of a stomach on ultrasound was diagnostic of pure oesophageal atresia. Polyhydramnios with intestinal dilation was diagnostic of intestinal obstruction. Although surgery was performed earlier in the infants diagnosed prenatally with ultrasound, mortality was no less than in the group that did not undergo a prenatal sonogram, probably because of the high incidence of associated anomalies. 相似文献
352.
353.
镉胁迫下大豆中镉的分布状况及其籽粒品质 总被引:18,自引:1,他引:18
溶液培养中0.5μmol·L-1镉胁迫浓度下,大豆表现出轻微受害症状,籽粒减产25 . 7%,而籽粒中粗脂肪和粗蛋白含量变化不大.镉在大豆中的积累分布状况为根>叶>籽>油,比例为32.100:1.690:1.000:0.003.大豆籽粒含镉4.89mg/kg,超过了国家环境标准规定的最高容许量.而大豆粗脂肪中含镉仅0.015mg/kg,远低于国家食品环境卫生标准.豆粕中含镉6.17mg/kg,表明大豆籽粒中的镉主要存在于粗蛋白和淀粉中. 相似文献
354.
While true mosaicism occurs in only 0–25 per cent of genetic amniocenteses, nearly 2–5 per cent of amniotic fluid cell cultures contain a second cell line. In the common practice of prenatal diagnosis, an aberrant cell line confined to a single colony is usually disregarded. We present a case of mosaic trisomy 14 which was not detected on initial chromosome analysis. At birth, multiple malformations were apparent. Newborn cytogenetic studies revealed mosaicism [46,XX/46,XX,-14,+i(14q)] with an isochromosome 14 in 37 per cent of lymphocytes. Additional cells from the initial amniotic fluid culture were analysed post-delivery and the isochromosome 14 identified in only one of 12 total colonies. This case illustrates two important lessons in prenatal diagnosis. First, amniotic fluid cell cultures may not accurately reflect the relative distribution of the normal and abnormal cell lines within a mosaic fetus. Second, while it is generally reasonable to disregard mosaicism confined to a single colony, this policy will, on rare occasion, result in diagnostic error. This should be taken into consideration, particularly when dealing with autosomal trisomies potentially compatible with livebirth. 相似文献
355.
356.
357.
358.
Manganese-oxidizing fungi and bacteria 总被引:1,自引:0,他引:1
The Science of Nature - 相似文献
359.
The lessons of history indicate that mismanagement of natural resources and the environment often leads to potentially adverse consequences.The increasing interest in economic development,particularly in the developing countries of the world coupled with increasing population pressures and the globalization of economic activity is placing noticeable stresses on the ultimate sustainability of both human and environmental systems.Sustainable development is not a new concept.It has been an area of concern for different elements of society for some time.Yet efforts to understand the implications of sustainable development have not,until recently,been formalized.We have focused singularly on economic development and environmental quality as if they were mutually exclusive.This paper focuses on the concept of concurrency as both a conceptual framework and practicable method of understanding and implementing the ecology and economy of sustainability. 相似文献
360.