全文获取类型
收费全文 | 8190篇 |
免费 | 90篇 |
国内免费 | 247篇 |
专业分类
安全科学 | 162篇 |
废物处理 | 408篇 |
环保管理 | 926篇 |
综合类 | 1373篇 |
基础理论 | 2010篇 |
污染及防治 | 2029篇 |
评价与监测 | 611篇 |
社会与环境 | 959篇 |
灾害及防治 | 49篇 |
出版年
2023年 | 60篇 |
2022年 | 132篇 |
2021年 | 106篇 |
2020年 | 68篇 |
2019年 | 101篇 |
2018年 | 146篇 |
2017年 | 155篇 |
2016年 | 214篇 |
2015年 | 161篇 |
2014年 | 265篇 |
2013年 | 707篇 |
2012年 | 286篇 |
2011年 | 381篇 |
2010年 | 316篇 |
2009年 | 349篇 |
2008年 | 400篇 |
2007年 | 409篇 |
2006年 | 314篇 |
2005年 | 297篇 |
2004年 | 293篇 |
2003年 | 282篇 |
2002年 | 275篇 |
2001年 | 346篇 |
2000年 | 218篇 |
1999年 | 118篇 |
1998年 | 87篇 |
1997年 | 85篇 |
1996年 | 107篇 |
1995年 | 127篇 |
1994年 | 97篇 |
1993年 | 86篇 |
1992年 | 90篇 |
1991年 | 92篇 |
1990年 | 80篇 |
1989年 | 71篇 |
1988年 | 71篇 |
1987年 | 75篇 |
1986年 | 52篇 |
1985年 | 64篇 |
1984年 | 63篇 |
1983年 | 59篇 |
1982年 | 58篇 |
1981年 | 66篇 |
1980年 | 47篇 |
1979年 | 46篇 |
1977年 | 38篇 |
1976年 | 37篇 |
1974年 | 34篇 |
1973年 | 44篇 |
1972年 | 51篇 |
排序方式: 共有8527条查询结果,搜索用时 250 毫秒
991.
992.
993.
R. K. Guthrie D. S. Cherty R. N. Ferebee 《Journal of the American Water Resources Association》1974,10(2):304-310
ABSTRACT: The naturally occurring, aerobic, heterotrophic bacterial populations of two impounded ecosystems were studied in a laboratory tank system. One reservoir received runoff from a rural drainage basin only, while the second received treated municipal sewage, industrial waste and heavy recreational use. Water from each reservoir was treated with 1.4 ppm final concentration of diuron and studied for total bacterial counts and nutritional source types. Control tanks were studied concurrently. Total counts increased shortly after diuron addition; however, this was followed by a decrease to a level below the control. Reduction in diversity was significantly greater in water from the polluted reservoir, but chromagenic bacteria were significantly reduced in the non-polluted reservoir. The effects on isolation of specific nutrient types from the two systems following herbicide addition revealed that starch utilizers were the most affected group. Bacteria growing on protein or glucose salts were essentially unaffected. (KEY TERMS: Diuron; Bacteria; Herbicides in Aquatic Environments; Chromagenic Bacteria: Natural Aquatic Bacteria.) 相似文献
994.
Second trimester amniocentesis has traditionally been utilized for prenatal genetic diagnosis. Chorionic villi sampling (CVS) is presently offered as an alternative. The occurrence of fetomaternal bleed (FMB) during CVS could increase the rate of post sampling abortion and, additionally, be of significance in patients at risk for isoimmunization. Detection and quantitation of FMB can be accomplished by the determination of changes in maternal serum alpha-fetoprotein (MSAFP) before and after CVS. 相似文献
995.
Using the example of bats inhabiting the Volga region, the cases in which the anthropogenic factor creates favorable conditions for these animals or significantly reduces their diversity of their fauna are considered. In this context, an opinion concerning the approaches to the conservation of bats is formulated. 相似文献
996.
Fesenko S. V. Spiridonov S. I. Sanzharova N. I. Anisimov V. S. Aleksakhin R. M. 《Russian Journal of Ecology》2002,33(3):170-177
A mathematical model was constructed to simulate the processes of 137Cs migration in peat soils and its uptake by vegetation. Model parameters were assessed and the pattern of 137Cs distribution over soil profile was predicted in case of peat soils, which are typical of the Russian regions contaminated after the Chernobyl accident. The ecological half-life of 137Cs in the plant-root soil zone was calculated, and a long-term prognosis of the radionuclide uptake by plants was made. 相似文献
997.
O. N. Luk’yanova 《Russian Journal of Ecology》2006,37(3):205-209
The functional state of the indicator species, the Gray mussel Crenomytilus grayanus (Bivalvia), has been analyzed in five areas of Peter the Great Bay exposed to anthropogenic pollution. The following indices of the state of mussels have been used: molecular biomarkers of energy metabolism—Na+,K+-ATPase, Mg2+-ATPase, and total ATPase activity—as well as the level of lipid peroxidation (LPO) and glutathione concentration in the hepatopancreas, gills, and gonads of mussels. The activity of ATPases, LPO level, and glutathione concentration significantly change in mussels from polluted areas relative to those in mussels from a conventionally unpolluted area (a bay in the Far Eastern State Marine Reserve). The molecular biomarkers used in the study provide reliable information on animal metabolism in impact areas. With consideration of the data obtained, it is concluded that the state of mussels in polluted areas is impaired. 相似文献
998.
E. G. Plotnikova D. O. Rybkina L. N. Anan’ina O. V. Yastrebova V. A. Demakov 《Russian Journal of Ecology》2006,37(4):233-240
Microorganisms capable of degrading monocyclic and polycyclic aromatic hydrocarbons and several chlorinated aromatic compounds were isolated from soils polluted with industrial waste from chemical plants. They were identified as representatives of the genera Pseudomonas, Flavobacterium, Alcaligenes, Rhodococcus, Microbacterium, Cellulomonas, Arthrobacter, and Brevibacterium. Among them, bacteria capable of utilizing xenobiotics in a wide range of ambient temperatures and pH and in the presence of high sodium chloride concentrations were revealed. 相似文献
999.
The reproduction dynamics of nonsynanthropic rodents living in urbanized areas was compared with that of rodents from natural communities. The number of females in a community and the number of embryos and placental spots per female were estimated. The mechanisms providing for the maintenance of population size were different in different habitats. In particular, the urban communities of murine rodents proved to have a higher reproductive potential. 相似文献
1000.
A. F. Holland N. K. Mountford M. H. Hiegel K. R. Kaumeyer J. A. Mihursky 《Marine Biology》1980,57(3):221-235
The importance of predators in controlling the densities of infaunal (>0.5 mm) organisms was investigated in the mesohaline region of the Upper Chesapeake Bay (USA) using field experiments. The role of predators in controlling infaunal density and community characteristics varied with habitat type, season (i.e., predator abundance) and developmental or successional stage of the community. Few infaunal species were adversely affected by predator exclusion. Species that increased greatly in abundance in the absence of predators (e.g. Eteone heteropoda, Streblospio benedicti, Nereis succinea, and juvenile Macoma balthica and Mya arenaria) lived near the sediment-water interface and had major population pulses from fall through spring. Species whose abundances increased moderately or were not affected by predator exclusion were deeper burrowing organisms (e.g. Heteromastus filiformis and adult Mya arenaria), or were relatively small organisms (e.g. Paraprionospio pinnata, Scolecolepides viridis and Peloscolex gabriellae) whose principal predators could be other members of the infauna. Competition did not appear to be an important factor controlling infaunal density in these experiments.This work is Contribution No. 973 of the Center for Environmental and Estuarine Studies of the University of Maryland 相似文献