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   30383篇
  免费   351篇
  国内免费   254篇
安全科学   1022篇
废物处理   1466篇
环保管理   4117篇
综合类   4555篇
基础理论   7872篇
环境理论   9篇
污染及防治   7525篇
评价与监测   2160篇
社会与环境   2074篇
灾害及防治   188篇
  2023年   139篇
  2022年   274篇
  2021年   333篇
  2020年   206篇
  2019年   247篇
  2018年   446篇
  2017年   474篇
  2016年   739篇
  2015年   552篇
  2014年   871篇
  2013年   2543篇
  2012年   1032篇
  2011年   1376篇
  2010年   1127篇
  2009年   1171篇
  2008年   1443篇
  2007年   1366篇
  2006年   1240篇
  2005年   1106篇
  2004年   1063篇
  2003年   1014篇
  2002年   958篇
  2001年   1100篇
  2000年   774篇
  1999年   499篇
  1998年   371篇
  1997年   394篇
  1996年   406篇
  1995年   473篇
  1994年   406篇
  1993年   356篇
  1992年   379篇
  1991年   357篇
  1990年   334篇
  1989年   326篇
  1988年   301篇
  1987年   247篇
  1986年   248篇
  1985年   257篇
  1984年   272篇
  1983年   259篇
  1982年   274篇
  1981年   228篇
  1980年   170篇
  1979年   184篇
  1978年   163篇
  1977年   133篇
  1975年   138篇
  1973年   168篇
  1972年   142篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
951.
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   
952.
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   
953.
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   
954.
Environmental Economics and Policy Studies - The classical DICE model is a widely accepted integrated assessment model for the joint modeling of economic and climate systems, where all model state...  相似文献   
955.
In the Ohio River (OR), backwater confluence sedimentation dynamics are understudied, however, these river features are expected to be influential on the system’s ecological and economic function when integrated along the river’s length. In the following paper, we test the efficacy of organic and inorganic tracers for sediment fingerprinting in backwater confluences; we use fingerprinting results to evidence sediment dynamics controlling deposition patterns in confluences used for wetland and marina functions; and we quantify the spatial extent of tributary drainages with wetland and marina features in OR confluences. Both organic and inorganic tracers statistically differentiate sediment from stream and river end‐members. Carbon and nitrogen stable isotopes produce greater uncertainty in fingerprinting results than inorganic elemental tracers. Uncertainty analysis of the nonconservative tracer term in the organic matter fingerprinting application estimates an apparent enrichment of the carbon stable isotopes during instream residence, and the nonconservativeness is quantified with a statistical approach unique to the fingerprinting literature. Wetland and marina features in OR confluences impact 42% and 11% of tributary drainage areas, respectively. Sediment dynamics show wetland and marina confluences experience deposition from river backwaters with longitudinally linear and nonlinear patterns, respectively, from sediment sources.  相似文献   
956.
We apply predictive weather metrics and land model sensitivities to improve the Colorado State University Water Irrigation Scheduler for Efficient Application (WISE). WISE is an irrigation decision aid that integrates environmental and user information for optimizing water use. Rainfall forecasts and verification performance metrics are used to estimate predictive rainfall probabilities that are used as input data within the irrigation decision aid. These input data errors are also used within a land model sensitivity study to diagnose important prognostic water movement behaviors for irrigation tool development purposes simultaneously performing the analysis in space and time. Thus, important questions such as “how long can a crop water application be delayed while maintaining crop yield production?” are addressed by evaluating crop growth stage interactions as a function of soil depth (i.e., space), rainfall events (i.e., time), and their probabilistic uncertainties. Editor’s note : This paper is part of the featured series on Optimizing Ogallala Aquifer Water Use to Sustain Food Systems. See the February 2019 issue for the introduction and background to the series.  相似文献   
957.
This research seeks for improved understanding regarding the interaction of meaningful work and the work–family interface. Existing literature suggests that experiencing a sense of calling toward work makes the work domain particularly salient to employees compared to other life domains. In this article, we draw on this idea, rooted in identity theory, to hypothesize that a sense of calling toward work diminishes the effects of work–family conflict and work–family enrichment on employee's job and life satisfaction. We test these ideas in two studies. First, we surveyed an alumni sample of 598 employees from various jobs, industries, and job levels. Then, in a constructive replication, we surveyed 327 employees using a time-lagged design. Calling was found to significantly buffer the effect of work–family conflict on job satisfaction in Study 2, but not Study 1. Calling did not buffer the effect of conflict on life satisfaction in either study. However, both studies demonstrated that calling attenuated (substituted for) the effect of work–family enrichment on job satisfaction. Study 1 supported the idea that calling attenuates the effect of enrichment on life satisfaction; however, this interactive effect was reversed in Study 2, contrary to expectations. We discuss implications for theory and practice related to callings and career choices, as well as for the role of calling and work identity in the work–family interface.  相似文献   
958.
Environmental Management - Landscapes are changing, with rural areas becoming increasingly urbanized. Children and adolescents are underrepresented in the sense-of-place literature. Our study aimed...  相似文献   
959.
Conservation and management of marine biodiversity depends on biomonitoring of marine habitats, but current approaches are resource-intensive and require different approaches for different organisms. Environmental DNA (eDNA) extracted from water samples is an efficient and versatile approach to detecting aquatic animals. In the ocean, eDNA composition reflects local fauna at fine spatial scales, but little is known about the effectiveness of eDNA-based monitoring of marine communities at larger scales. We investigated the potential of eDNA to characterize and distinguish marine communities at large spatial scales by comparing vertebrate species composition among marine habitats in Qatar, the Arabian Gulf (also known as the Persian Gulf), based on eDNA metabarcoding of seawater samples. We conducted species accumulation analyses to estimate how much of the vertebrate diversity we detected. We obtained eDNA sequences from a diverse assemblage of marine vertebrates, spanning 191 taxa in 73 families. These included rare and endangered species and covered 36% of the bony fish genera previously recorded in the Gulf. Sites of similar habitat type were also similar in eDNA composition. The species accumulation analyses showed that the number of sample replicates was insufficient for some sampling sites but suggested that a few hundred eDNA samples could potentially capture >90% of the marine vertebrate diversity in the study area. Our results confirm that seawater samples contain habitat-characteristic molecular signatures and that eDNA monitoring can efficiently cover vertebrate diversity at scales relevant to national and regional conservation and management.  相似文献   
960.
In November 1928, Theodore Jr. and Kermit Roosevelt led an expedition to China with the expressed purpose of being the first Westerners to kill the giant panda (Ailuropoda melanoleuca). The expedition lasted 8 months and resulted in the brothers shooting a giant panda in the mountains of Sichuan Province. Given the concurrent attention in the popular press describing this celebrated expedition, the giant panda was poised to be trophy hunted much like other large mammals around the world. Today, however, the killing of giant pandas, even for the generation of conservation revenue, is unthinkable for reasons related to the species itself and the context, in time and space, in which the species was popularized in the West. We found that the giant panda's status as a conservation symbol, exceptional charisma and gentle disposition, rarity, value as a nonconsumptive ecotourism attraction, and endemism are integral to the explanation of why the species is not trophy hunted. We compared these intrinsic and extrinsic characteristics with 20 of the most common trophy-hunted mammals to determine whether the principles applying to giant pandas are generalizable to other species. Although certain characteristics of the 20 trophy-hunted mammals aligned with the giant panda, many did not. Charisma, economic value, and endemism, in particular, were comparatively unique to the giant panda. Our analysis suggests that, at present, exceptional characteristics may be necessary for certain mammals to be excepted from trophy hunting. However, because discourse relating to the role of trophy hunting in supporting conservation outcomes is dynamic in both science and society, we suspect these valuations will also change in future.  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