全文获取类型
收费全文 | 14887篇 |
免费 | 110篇 |
国内免费 | 96篇 |
专业分类
安全科学 | 320篇 |
废物处理 | 727篇 |
环保管理 | 1647篇 |
综合类 | 3048篇 |
基础理论 | 3292篇 |
环境理论 | 9篇 |
污染及防治 | 4196篇 |
评价与监测 | 1010篇 |
社会与环境 | 781篇 |
灾害及防治 | 63篇 |
出版年
2022年 | 206篇 |
2021年 | 201篇 |
2020年 | 96篇 |
2019年 | 110篇 |
2018年 | 282篇 |
2017年 | 229篇 |
2016年 | 408篇 |
2015年 | 268篇 |
2014年 | 447篇 |
2013年 | 1171篇 |
2012年 | 528篇 |
2011年 | 640篇 |
2010年 | 504篇 |
2009年 | 517篇 |
2008年 | 633篇 |
2007年 | 690篇 |
2006年 | 626篇 |
2005年 | 476篇 |
2004年 | 468篇 |
2003年 | 467篇 |
2002年 | 414篇 |
2001年 | 469篇 |
2000年 | 348篇 |
1999年 | 229篇 |
1998年 | 125篇 |
1997年 | 134篇 |
1996年 | 115篇 |
1995年 | 175篇 |
1994年 | 163篇 |
1993年 | 134篇 |
1992年 | 137篇 |
1991年 | 153篇 |
1990年 | 128篇 |
1989年 | 136篇 |
1988年 | 136篇 |
1987年 | 118篇 |
1986年 | 86篇 |
1985年 | 105篇 |
1984年 | 124篇 |
1983年 | 127篇 |
1982年 | 128篇 |
1981年 | 97篇 |
1980年 | 95篇 |
1979年 | 108篇 |
1978年 | 89篇 |
1977年 | 86篇 |
1976年 | 79篇 |
1975年 | 95篇 |
1974年 | 102篇 |
1965年 | 88篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
This work, carried out within the framework of the PRISMA II project, aims at evaluating the effects of the Po River flow on primary productivity, measured by C with in situ sample incubations. A total of four cruises was carried out in late winter and early summer (1996-1998) along transects from the coast offshore. In both seasons, the highest primary productivity was found in the most oligohaline stations. The effects of the Po River inputs were therefore clearly evident in the westernmost area, both in high productivity values and in the shape of productivity profiles. In late winter, extensive blooms of Skeletonema costatum and Pseudo-nitzschia delicatissima resulted in productivity values that were sometimes higher than in early summer. In early summer 1996, greatly reduced river flow clearly influenced productivity which was much lower than in 1997. 相似文献
3.
The typical parameters of acid precipitation are evaluated in the forest of Vallombrosa (Tuscan Appennines) during the dry period 1988-89. Individual rain events (dry and wet deposition) were sampled in a clearing of the forest and below the canopy of an evergreen tree as well as a deciduous broadleaf tree.
In atmospheric precipitation the pH values usually vary around 4.4, with neutralization in the hot season due to calcareous material from distant sources. Relatively large concentrations of Pb and Cd are found in rain, but only in a small amount in canopy leachate. Aluminium, manganese and iron are more significantly washed off than Pb and Cd. 相似文献
In atmospheric precipitation the pH values usually vary around 4.4, with neutralization in the hot season due to calcareous material from distant sources. Relatively large concentrations of Pb and Cd are found in rain, but only in a small amount in canopy leachate. Aluminium, manganese and iron are more significantly washed off than Pb and Cd. 相似文献
4.
5.
6.
7.
T. Stoichev L. Makedonski T. Trifonova M. Stancheva F. Ribarova 《Chemistry and Ecology》2007,23(3):191-200
In spite of a worldwide reduction in the utilization of organochlorine pesticides (OCPs), they are still a problem for the aquatic environment and human health. The Black Sea is still being polluted with persistent chemicals, including OCPs. Aquatic organisms (sprat, scad, bluefish, shad, belted bonito, goby, and black mussel) with different feeding behaviours were sampled on a seasonal basis from the Bulgarian region of the Black Sea, and the concentrations of 13 OCP residues were determined. Although many of the OCPs were not detected in the samples, in all samples 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane (DDT) was present mainly in the form of its metabolites 1,1-dichloro-2,2-bis(4-chlorophenyl) ethane (DDD) and 1,1-dichloro-2,2-bis(4-chlorophenyl) ethylene (DDE). Only about 12% of the total DDT was present as the parent compound pp-DDT, which suggests that it was not being used recently in the region. The total DDT concentrations were generally below 150 μg kg-1 fresh weight, but higher levels—up to 354 μg kg-1 fresh weight—were also measured for fish species with a high fat content. Between-species differences were observed, even when the concentrations were presented on a fat-level basis. DDT concentrations did not show any significant changes over the 2-yr sampling period. Fish sampled in the northern areas of the Bulgarian Black Sea coast seemed to contain higher DDT levels than those from the southern areas, suggesting a major (historical) influence of the Danube River. For permanent monitoring purposes, the utility of Black Sea gobies and scad should be considered. 相似文献
8.
9.
In the past 20 years a variety of indices have been suggested for measuring the severity of trauma, however none of them meets the requirement of being a simple and objective instrument that can be utilized efficiently by lay persons and providers of health services without previous experience in triaging. A new system has been proposed which meets this requirement and which has been validated with 197 injured persons at the emergency ward of the Valle University Hospital in Call, Colombia. The instrument showed a high level of concordance with the conventional triaging method and classifies victims into four categories: critical with recovery unlikely, critical but recoverable, moderately serious, and ambulatory. There is discussion on the reliability of this instrument and it is recommended that it be validated with victims from larger disasters. Regardless, it has the advantage of being specific and free of the subjectivity that characterizes other indices. 相似文献
10.