全文获取类型
收费全文 | 20390篇 |
免费 | 181篇 |
国内免费 | 201篇 |
专业分类
安全科学 | 536篇 |
废物处理 | 987篇 |
环保管理 | 2429篇 |
综合类 | 2681篇 |
基础理论 | 5304篇 |
环境理论 | 4篇 |
污染及防治 | 5601篇 |
评价与监测 | 1652篇 |
社会与环境 | 1456篇 |
灾害及防治 | 122篇 |
出版年
2023年 | 93篇 |
2022年 | 215篇 |
2021年 | 217篇 |
2020年 | 139篇 |
2019年 | 178篇 |
2018年 | 326篇 |
2017年 | 320篇 |
2016年 | 525篇 |
2015年 | 363篇 |
2014年 | 576篇 |
2013年 | 1751篇 |
2012年 | 678篇 |
2011年 | 862篇 |
2010年 | 803篇 |
2009年 | 785篇 |
2008年 | 888篇 |
2007年 | 979篇 |
2006年 | 874篇 |
2005年 | 718篇 |
2004年 | 726篇 |
2003年 | 708篇 |
2002年 | 672篇 |
2001年 | 911篇 |
2000年 | 633篇 |
1999年 | 394篇 |
1998年 | 274篇 |
1997年 | 246篇 |
1996年 | 292篇 |
1995年 | 271篇 |
1994年 | 250篇 |
1993年 | 233篇 |
1992年 | 242篇 |
1991年 | 208篇 |
1990年 | 214篇 |
1989年 | 219篇 |
1988年 | 198篇 |
1987年 | 158篇 |
1986年 | 127篇 |
1985年 | 138篇 |
1984年 | 169篇 |
1983年 | 153篇 |
1982年 | 193篇 |
1981年 | 134篇 |
1980年 | 119篇 |
1979年 | 152篇 |
1978年 | 118篇 |
1977年 | 108篇 |
1976年 | 101篇 |
1975年 | 83篇 |
1974年 | 88篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Pradeep S. Salve 《Local Environment》2020,25(8):627-630
ABSTRACT The absence of a vaccine and effective treatment for COVID-19 has created public panic and burdened the health systems in most countries. Along with health workers’, sanitation personnel are also working at the frontlines in the war against the disease by keeping cities clean. Sanitation workers are engaged in Drudgery, Dangerous, Dirty and Dehumanising work that makes them vulnerable for developing the chronic respiratory diseases due to the exposure of various hazardous materials and toxic gases that are emitted from the solid waste. The sanitation workers working on a contractual basis are excluded from the labour policies and welfare programs who are playing a vital role in fighting the pandemic. Women sanitation workers are even more vulnerable because most of them are non-literate, poor in financial management and under-represented in the sanitation employee’s union. The local and state governments should protect and safeguard sanitation workers by providing them with adequate protective equipment, ensure payment of paying adequate salaries and provide them with health insurance. 相似文献
992.
993.
Predation is often considered as one of the most important biotic factor determining the success of exotic species. The freshwater amphipod Gammarus roeseli has widely colonized Western Europe, where it is frequently found in sympatry with the native species (Gammarus pulex). Previous laboratory experiments revealed that G. roeseli may have an advantage over G. pulex through differential predation by native fish (brown trout). Morphological anti-predator defences (spines) were found responsible for lower rates of predation on the invasive G. roeseli. Here, using both field surveys and laboratory experiments, we tested if a differential of predation exists with other fish predators naturally encountered by gammarids. The main predators present in our field site were nocturnal benthic feeders (mainly bullheads, Cottus gobio). Fish diet analysis showed that, compared to its global availability in the river, G. roeseli was less consumed than G. pulex. In the field, however, G. roeseli was found mainly in the aquatic vegetation whereas G. pulex was found in all habitat types. Laboratory experiments in microcosms revealed that G. roeseli was less prone to predation by C. gobio only when vegetation was present. Depending on the type of predator, the differential of predation could therefore be mediated by antipredator behaviour, and a better usage of refuges, rather than by morphological defences. 相似文献
994.
IntroductionCeramic,consistofearthymaterialslikeclaykaolin ,limestoneandsandglass .Ceramicmaterialsarenonmetalic ,inorganiccompoundsprimaryoxides ,alsocarbides ,nitridesandsilicides .Twotypesofbondingmechanismsoccurinceramicmaterial ,ionicandcovalent.Theo… 相似文献
995.
本文主要研究了肯尼亚姆瓦彻湾(属于浅潮滩红树林湿地)泥沙交换的动力机制.该港湾属于半日潮,大、小潮的潮差分别为.2m和1.4m,大潮高水位的水面面积为17km2. 相似文献
996.
997.
998.
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
999.
1000.