全文获取类型
收费全文 | 84946篇 |
免费 | 1219篇 |
国内免费 | 1061篇 |
专业分类
安全科学 | 3431篇 |
废物处理 | 3033篇 |
环保管理 | 13267篇 |
综合类 | 20881篇 |
基础理论 | 25572篇 |
环境理论 | 74篇 |
污染及防治 | 12069篇 |
评价与监测 | 5129篇 |
社会与环境 | 3291篇 |
灾害及防治 | 479篇 |
出版年
2022年 | 713篇 |
2021年 | 779篇 |
2020年 | 640篇 |
2019年 | 853篇 |
2018年 | 1060篇 |
2017年 | 1079篇 |
2016年 | 2086篇 |
2015年 | 1814篇 |
2014年 | 2555篇 |
2013年 | 9205篇 |
2012年 | 1958篇 |
2011年 | 2053篇 |
2010年 | 3149篇 |
2009年 | 3288篇 |
2008年 | 1542篇 |
2007年 | 1352篇 |
2006年 | 1887篇 |
2005年 | 1969篇 |
2004年 | 2287篇 |
2003年 | 2107篇 |
2002年 | 1665篇 |
2001年 | 1866篇 |
2000年 | 1699篇 |
1999年 | 1357篇 |
1998年 | 1307篇 |
1997年 | 1287篇 |
1996年 | 1415篇 |
1995年 | 1540篇 |
1994年 | 1441篇 |
1993年 | 1284篇 |
1992年 | 1272篇 |
1991年 | 1252篇 |
1990年 | 1198篇 |
1989年 | 1168篇 |
1988年 | 1007篇 |
1987年 | 956篇 |
1986年 | 982篇 |
1985年 | 1049篇 |
1984年 | 1143篇 |
1983年 | 1157篇 |
1982年 | 1168篇 |
1981年 | 1087篇 |
1980年 | 933篇 |
1979年 | 905篇 |
1978年 | 812篇 |
1977年 | 706篇 |
1976年 | 631篇 |
1975年 | 591篇 |
1973年 | 615篇 |
1972年 | 619篇 |
排序方式: 共有10000条查询结果,搜索用时 77 毫秒
71.
Use of genetic,climatic, and microbiological data to inform reintroduction of a regionally extinct butterfly 下载免费PDF全文
Vlad Dincă Zsolt Bálint Raluca Vodă Leonardo Dapporto Paul D. N. Hebert Roger Vila 《Conservation biology》2018,32(4):828-837
Species reintroductions are increasingly used as means of mitigating biodiversity loss. Besides habitat quality at the site targeted for reintroduction, the choice of source population can be critical for success. The butterfly Melanargia russiae (Esper´s marbled white) was extirpated from Hungary over 100 years ago, and a reintroduction program has recently been approved. We used museum specimens of this butterfly, mitochondrial DNA data (mtDNA), endosymbiont screening, and climatic‐similarity analyses to determine which extant populations should be used for its reintroduction. The species displayed 2 main mtDNA lineages across its range: 1 restricted to Iberia and southern France (Iberian lineage) and another found throughout the rest of its range (Eurasian lineage). These 2 lineages possessed highly divergent wsp alleles of the bacterial endosymbiont Wolbachia. The century‐old Hungarian specimens represented an endemic haplotype belonging to the Eurasian lineage, differing by one mutation from the Balkan and eastern European populations. The Hungarian populations of M. russiae occurred in areas with a colder and drier climate relative to most sites with extant known populations. Our results suggest the populations used for reintroduction to Hungary should belong to the Eurasian lineage, preferably from eastern Ukraine (genetically close and living in areas with the highest climatic similarity). Materials stored in museum collections can provide unique opportunities to document historical genetic diversity and help direct conservation. 相似文献
72.
Estimating abundance without recaptures of marked pallid sturgeon in the Mississippi River 下载免费PDF全文
Nicholas A. Friedenberg Jan Jeffrey Hoover Krista Boysen K. Jack Killgore 《Conservation biology》2018,32(2):457-465
Abundance estimates are essential for assessing the viability of populations and the risks posed by alternative management actions. An effort to estimate abundance via a repeated mark‐recapture experiment may fail to recapture marked individuals. We devised a method for obtaining lower bounds on abundance in the absence of recaptures for both panmictic and spatially structured populations. The method assumes few enough recaptures were expected to be missed by random chance. The upper Bayesian credible limit on expected recaptures allows probabilistic statements about the minimum number of individuals present in the population. We applied this method to data from a 12‐year survey of pallid sturgeon (Scaphirhynchus albus) in the lower and middle Mississippi River (U.S.A.). None of the 241 individuals marked was recaptured in the survey. After accounting for survival and movement, our model‐averaged estimate of the total abundance of pallid sturgeon ≥3 years old in the study area had a 1%, 5%, or 25% chance of being <4,600, 7,000, or 15,000, respectively. When we assumed fish were distributed in proportion to survey catch per unit effort, the farthest downstream reach in the survey hosted at least 4.5–15 fish per river kilometer (rkm), whereas the remainder of the reaches in the lower and middle Mississippi River hosted at least 2.6–8.5 fish/rkm for all model variations examined. The lower Mississippi River had an average density of pallid sturgeon ≥3 years old of at least 3.0–9.8 fish/rkm. The choice of Bayesian prior was the largest source of uncertainty we considered but did not alter the order of magnitude of lower bounds. Nil‐recapture estimates of abundance are highly uncertain and require careful communication but can deliver insights from experiments that might otherwise be considered a failure. 相似文献
73.
Regional Environmental Change - The threat of flooding poses a considerable challenge for justice. Not only are more citizens becoming exposed to risk, but they are expected to play increasingly... 相似文献
74.
Inna E. Popova Matthew J. Morra Sanjai J. Parikh 《Journal of environmental science and health. Part. B》2019,54(1):35-40
Veterinary antibiotics used in agriculture can be introduced into the environment through land application of animal manure, accumulating in soils and groundwaters and posing a significant risk to human health and animal well-being. As the analysis of tetracyclines in soil is challenging due to their strong interaction with soil minerals and organic carbon, the objective of this study was to develop a reliable and reproducible method for quantitative analysis of chlortetracycline and oxytetracycline, and their respective metabolites in soils. A method based on pressurized liquid extraction (PLE) with in-cell clean-up was developed for the extraction of chlortetracycline and oxytetracycline and four likely metabolites from a set of four soils. Optimized conditions included a cell size of 22?mL, soil loading of 5?g, pH of 8.0, methanol:water ratio of 3:1, 50?°C, and two cycles. Soil extracts were analysed by high-performance liquid chromatography (HPLC) coupled with ion trap mass spectrometry (MS). Recoveries of seven tetracyclines from soil ranged from 41% to 110%. The limits of detection for tetracyclines were 0.08–0.3 µg g?1 soil, and intra- and inter-day variation ranged from 0.12–0.34%. The proposed PLE method is suitable for quantification of tetracyclines in agricultural soils at typical concentrations expected in contaminated environments. 相似文献
75.
Tohamy Hossam G. Gad El-Karim Dina R. El-Sayed Yasser S. 《Environmental science and pollution research international》2019,26(21):21524-21534
Environmental Science and Pollution Research - Hydroxyurea (HDU), a class of antineoplastic drugs, has a powerful efficacy in the treatment of several types of malignancies. However, it has... 相似文献
76.
Francisco M. Baena-Moreno Mónica Rodríguez-Galán Fernando Vega Luis F. Vilches Benito Navarrete 《International Journal of Green Energy》2019,16(5):401-412
Biomethane production through biogas upgrading is a promising renewable energy for some industries which could be part of the equilibrium needed with fossil fuels consumption to achieve a sustainable society. This paper presents a comprehensive list of biogas upgrading technologies focused on carbon dioxide removal as well as recent advances reported by researcher with wide expertise in this topic. Additionally, an extensive costs–performance comparison among the technologies studied is discussed. Among the different alternatives, chemical scrubbing stood out to achieve high biomethane purities while cryogenic technologies proved to be effective against methane losses. Regarding the different costs, water scrubbing and membrane separation seem to be the most affordable techniques. 相似文献
77.
The illegal wildlife trade has emerged as a growing and urgent environmental issue. Stakeholders involved in the efforts to curb wildlife trafficking include nongovernmental organizations (NGOs), academia, and state government and enforcement bodies. The extent to which these stakeholders work and communicate among each other is fundamental to effectively combatting illicit trade. Using the United Kingdom as a case study, we used a social network analysis and semistructured interviews of stakeholders to assess communication relationships in the counter wildlife trafficking community. The NGOs consistently occupied 4 of the 5 most central positions in the generated networks, whereas academic institutions routinely occupied 4 of the 5 most peripheral positions. However, NGOs were the least diverse in their communication practices compared with the other stakeholder groups. Stakeholders identified personal relationships as the most important aspect of functioning communication. Participant insights also showed that stakeholder-specific variables (e.g., ethical and confidentiality concerns), competition, and fundraising can have a confounding effect on intercommunication. Evaluating communication networks and intrastakeholder communication trends is essential to creating cohesive, productive, and efficient responses to the challenges of combatting illegal wildlife trade. Article impact statement: Communication among those combatting illegal wildlife trade is confounded by stakeholder variables (ethics, confidentiality), competition, and fundraising. 相似文献
78.
Environmental Fluid Mechanics - Turbulent flux measurements in the atmospheric surface layer (ASL), acquired from a vertical tower of sonic anemometers, are used to investigate the transient... 相似文献
79.
Russian Journal of Ecology - 相似文献
80.
Loizia Pantelitsa Neofytou Niki Zorpas Antonis A. 《Environmental science and pollution research international》2019,26(15):14766-14773
Environmental Science and Pollution Research - Food waste management (FWM) is considered to be an extremely important social issue besides an environmental one. Worldwide, it is estimated that 1.3... 相似文献