首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   30245篇
  免费   346篇
  国内免费   253篇
安全科学   1028篇
废物处理   1494篇
环保管理   4091篇
综合类   4505篇
基础理论   7855篇
环境理论   9篇
污染及防治   7448篇
评价与监测   2163篇
社会与环境   2064篇
灾害及防治   187篇
  2023年   137篇
  2022年   266篇
  2021年   327篇
  2020年   206篇
  2019年   250篇
  2018年   456篇
  2017年   474篇
  2016年   735篇
  2015年   548篇
  2014年   879篇
  2013年   2501篇
  2012年   1041篇
  2011年   1376篇
  2010年   1132篇
  2009年   1162篇
  2008年   1440篇
  2007年   1363篇
  2006年   1235篇
  2005年   1094篇
  2004年   1054篇
  2003年   1004篇
  2002年   954篇
  2001年   1097篇
  2000年   778篇
  1999年   494篇
  1998年   368篇
  1997年   388篇
  1996年   407篇
  1995年   473篇
  1994年   400篇
  1993年   352篇
  1992年   378篇
  1991年   358篇
  1990年   329篇
  1989年   323篇
  1988年   297篇
  1987年   242篇
  1986年   250篇
  1985年   253篇
  1984年   269篇
  1983年   258篇
  1982年   271篇
  1981年   224篇
  1980年   168篇
  1979年   181篇
  1978年   162篇
  1977年   135篇
  1975年   137篇
  1973年   167篇
  1972年   142篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
941.
In neonate ruminants, the acoustic structure of vocalizations may depend on sex, vocal anatomy, hormonal profiles and body mass and on environmental factors. In neonate wild-living Mongolian gazelles Procapra gutturosa, hand-captured during biomedical monitoring in the Daurian steppes at the Russian-Mongolian border, we spectrographically analysed distress calls and measured body mass of 22 individuals (6 males, 16 females). For 20 (5 male, 15 female) of these individuals, serum testosterone levels were also analysed. In addition, we measured relevant dimensions of the vocal apparatus (larynx, vocal folds, vocal tract) in one stillborn male Mongolian gazelle specimen. Neonate distress calls of either sex were high in maximum fundamental frequency (800–900 Hz), but the beginning and minimum fundamental frequencies were significantly lower in males than in females. Body mass was larger in males than in females. The levels of serum testosterone were marginally higher in males. No correlations were found between either body mass or serum testosterone values and any acoustic variable for males and females analysed together or separately. We discuss that the high-frequency calls of neonate Mongolian gazelles are more typical for closed-habitat neonate ruminants, whereas other open-habitat neonate ruminants (goitred gazelle Gazella subgutturosa, saiga antelope Saiga tatarica and reindeer Rangifer tarandus) produce low-frequency (<200 Hz) distress calls. Proximate cause for the high fundamental frequency of distress calls of neonate Mongolian gazelles is their very short, atypical vocal folds (4 mm) compared to the 7-mm vocal folds of neonate goitred gazelles, producing distress calls as low as 120 Hz.  相似文献   
942.
This study evaluated the microbiocidal efficacy of a cleaning and disinfection (C&D) treatment using stainless-steel coupons applied to three common types of animal mortality transport vehicles when exposed to agricultural conditions. Metal test coupons, inoculated with bacteriophage MS2, were affixed to the undercarriage of three types of animal mortality transport vehicles at various locations. Coupons were grimed by maneuvering the test vehicles down a series of wet dirt roads. Coupons were attached and extracted at various points to evaluate C&D performance with and without grime. C&D efficacy using a water-supplied pressure washing system and a dilute sodium hypochlorite (NaOCl) solution was determined by comparing the difference in recovered viable virus between positive control coupons and test coupons. The results demonstrated a relatively high surface decontamination efficacy, with all but one location showing >5 log reduction of MS2. Coupons located on the roll-off truck's inside-back bumper contained the highest level of grime and resulted in a 4 log reduction of MS2. There was no significant difference in C&D efficacy across vehicle types, but locations impacted by grime and lack of accessibility achieved lower efficacies on average. These findings suggest that common C&D protocols, when applied to farm mortality transport vehicles, are effective. Hard-to-access locations containing high levels of grime may be candidates for additional targeted treatment.  相似文献   
943.
Journal of Material Cycles and Waste Management - The current study aimed to determine the characteristics and kinetic parameters for the pyrolysis of printed circuit board (PCB) wastes including...  相似文献   
944.
Russian Journal of Ecology - The long-term dynamics (over more than 70 years) of pike infection by cestodes Triaenophorus crassus and T. nodulosus in the Rybinsk Reservoir (the Volga River) has...  相似文献   
945.
Russian Journal of Ecology - A study of the anthropogenic impacts on the on-shore aggregation of true seals was carried out at a haul-out located at the mouth of Piltun Bay (the northeastern part...  相似文献   
946.
Russian Journal of Ecology - To test the hypothesis that animals from habitats exposed to high anthropogenic pressure are more successful in adapting to captivity, immature narrow-skulled voles...  相似文献   
947.
Russian Journal of Ecology - Climate change entails shifts in the ranges of woody plants along both latitudinal and altitudinal gradients in the boreal forest biome. In this study,...  相似文献   
948.
Environment, Development and Sustainability - The COVID-19 pandemic has caused a global emergence, and the absence of a proven vaccine or medicine has led to the implementation of measures to...  相似文献   
949.
Environment, Development and Sustainability - Local residents near forests often collect non-timber forest products (NTFPs) for a variety of reasons, including food, medicine, firewood, religious...  相似文献   
950.
Environment, Development and Sustainability - Good air quality is highly essential to the well-being of mankind, all living organisms and the environment. The quality of air is degrading at a...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号