全文获取类型
收费全文 | 14169篇 |
免费 | 160篇 |
国内免费 | 118篇 |
专业分类
安全科学 | 429篇 |
废物处理 | 541篇 |
环保管理 | 2343篇 |
综合类 | 2265篇 |
基础理论 | 3627篇 |
环境理论 | 8篇 |
污染及防治 | 3540篇 |
评价与监测 | 893篇 |
社会与环境 | 697篇 |
灾害及防治 | 104篇 |
出版年
2023年 | 80篇 |
2022年 | 125篇 |
2021年 | 115篇 |
2020年 | 103篇 |
2019年 | 115篇 |
2018年 | 194篇 |
2017年 | 176篇 |
2016年 | 271篇 |
2015年 | 232篇 |
2014年 | 307篇 |
2013年 | 1176篇 |
2012年 | 430篇 |
2011年 | 587篇 |
2010年 | 502篇 |
2009年 | 543篇 |
2008年 | 619篇 |
2007年 | 615篇 |
2006年 | 565篇 |
2005年 | 510篇 |
2004年 | 423篇 |
2003年 | 457篇 |
2002年 | 429篇 |
2001年 | 495篇 |
2000年 | 380篇 |
1999年 | 242篇 |
1998年 | 174篇 |
1997年 | 186篇 |
1996年 | 197篇 |
1995年 | 220篇 |
1994年 | 219篇 |
1993年 | 185篇 |
1992年 | 158篇 |
1991年 | 192篇 |
1990年 | 186篇 |
1989年 | 178篇 |
1988年 | 145篇 |
1987年 | 136篇 |
1986年 | 140篇 |
1985年 | 116篇 |
1984年 | 154篇 |
1983年 | 141篇 |
1982年 | 153篇 |
1981年 | 144篇 |
1980年 | 121篇 |
1979年 | 151篇 |
1978年 | 101篇 |
1977年 | 98篇 |
1976年 | 83篇 |
1975年 | 82篇 |
1973年 | 81篇 |
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
11.
12.
J. B. Harcum Jim C. Loftis Robert C. Ward 《Journal of the American Water Resources Association》1992,28(3):469-478
ABSTRACT: The use of nonparametric tests for monotonic trend has flourished in recent years to support routine water quality data analyses. The validity of an assumption of independent, identically distributed error terms is an important concern in selecting the appropriate nonparametric test, as is the presence of missing values. Decision rules are needed for choosing between alternative tests and for deciding whether and how to pre-process data before trend testing. Several data pre-processing procedures in conjunction with the Mann-Kendall tau and the Seasonal Kendall test (with and without serial correlation correction) are evaluated using synthetic time series with generated serial correlation and missing data. A composite test (pre-testing for serial correlation followed by one of two trend tests) is evaluated and was found to perform satisfactorily. 相似文献
13.
I Chu D C Villeneuve B McDonald V E Secours V E Valli 《Journal of environmental science and health. Part. B》1987,22(3):303-317
Pentachlorotoluene (PCT) and pentabromotoluene (PBT) are environmental contaminants detected in the Great Lakes ecosystem. In view of the paucity of toxicity data and the potential for human exposure, a subacute (28 day) and a subchronic (91 day) study were conducted in the rat. In the subacute study, groups of 10 male and 10 female rats were fed the diet containing PCT or PBT at 0, 0.5, 5.0, 50 or 500 ppm for 28-days. In the subchronic study, the group size was increased to 15, the dose levels were 0, 0.05, 0.5, 5.0, 50 and 500 ppm in the diet and the exposure period was 91 days. Growth rate and food consumption were not affected by exposure to either chemical in the subacute and subchronic study. Clinical observations revealed no abnormalities. Decreased hemoglobin was observed in female rats fed 5.0 ppm PCT and higher levels in the subacute (28 day) study. In the same study the hematocrit value and erythrocyte numbers of females fed 5.0 or 500 ppm PCT diets were significantly lower than the control. In both subacute and subchronic studies mild dose-dependent histopathological changes were observed in the thyroid, liver and kidney of rats fed PCT and PBT diets. In general male rats were more susceptible than females to the treatment of PCT and PBT. Based on these data, it was concluded that the no observable adverse effect level for PCT was 50 ppm in the diet (3.5 mg/kg b.w./day) and that of PBT was 5.0 ppm (0.35 mg/kg b.w./day). 相似文献
14.
15.
Tanay B. Yıldırım Tutku Ak Zuhal Ölmez 《Environment, Development and Sustainability》2008,10(6):871-881
While the world is going into different tourism expectations, the tourism understanding in Turkey is defined as tourism in the sea-sand-sun triangle. However, it is possible to contribute to the income and local development of the indigenous people by developing nature-based tourism. Besides, with the sustainable use and preservation of the natural-cultural assets, the damage of the traditional tourism industry on the natural and cultural environment could be reduced. In this study, it is aimed to bring up the nature-based tourism concept in Çanakkale by evaluating the nature-based tourism industry in the general of Turkey and assessing the natural-cultural resources that Çanakkale comprehends. The most important areas that have a nature-based tourism potential in Çanakkale and the tourism activities that are most suitable for these areas have been determined. 相似文献
16.
17.
18.
19.
Certain hydrothermal vent invertebrates, e.g. Riftia pachyptila and Calyptogena magnifica, are clearly established as harboring dense populations of chemoautotrophic sulfur bacteria in specialized tissues. By contrast, the physiological characteristics of the abundant intracellular gill symbiont of the vent mussel Bathymodiolus thermophilus have been questioned. The low activities of enzymes diagnostic for CO2 fixation (Calvin cycle) and for sulfur-driven energy generation, as measured by other investigators, have been attributed to bacterial contamination of the gill surface. Based on research at the Galápagos Rift hydrothermal vents in 1988 and subsequent laboratory experiments, the current study confirms that the B. thermophilus symbiont is a psychrophile for which thiosulfate and sulfide stimulate CO2 fixation. It strongly indicates that the symbiont is a chemoautotroph by establishing the following: (1) Sulfide and thiosulfate can stimulate CO2 fixation by partially purified symbionts by up to 43-fold and 120-fold, respectively; (2) the ribulose-1,5-bisphosphate carboxylase/oxygenase activity of the symbiont is sufficient to account for its sulfide- or thiosulfate-stimulated CO2 incorporation; (3) the symbiont's molar growth yield on thiosulfate, as judged by CO2 incorporation, is indistinguishable from that of free-living chemoautotrophs. Due to the high protein-degrading activity of B. thermophilus gill lysate, it is also suggested that host lysis of symbionts plays a more important role in the nutrition of the vent mussel than in R. pachyptila or C. magnifica, for which no comparable protein-degrading activity was found. 相似文献
20.