全文获取类型
收费全文 | 20666篇 |
免费 | 159篇 |
国内免费 | 160篇 |
专业分类
安全科学 | 476篇 |
废物处理 | 763篇 |
环保管理 | 2325篇 |
综合类 | 6079篇 |
基础理论 | 4338篇 |
环境理论 | 5篇 |
污染及防治 | 4854篇 |
评价与监测 | 1132篇 |
社会与环境 | 943篇 |
灾害及防治 | 70篇 |
出版年
2018年 | 260篇 |
2017年 | 240篇 |
2016年 | 369篇 |
2015年 | 260篇 |
2014年 | 420篇 |
2013年 | 1441篇 |
2012年 | 480篇 |
2011年 | 679篇 |
2010年 | 608篇 |
2009年 | 694篇 |
2008年 | 709篇 |
2007年 | 747篇 |
2006年 | 649篇 |
2005年 | 565篇 |
2004年 | 597篇 |
2003年 | 573篇 |
2002年 | 539篇 |
2001年 | 726篇 |
2000年 | 496篇 |
1999年 | 333篇 |
1998年 | 232篇 |
1997年 | 230篇 |
1996年 | 216篇 |
1995年 | 278篇 |
1994年 | 268篇 |
1993年 | 238篇 |
1992年 | 254篇 |
1991年 | 256篇 |
1990年 | 288篇 |
1989年 | 261篇 |
1988年 | 204篇 |
1987年 | 202篇 |
1986年 | 196篇 |
1985年 | 205篇 |
1984年 | 218篇 |
1983年 | 216篇 |
1982年 | 213篇 |
1981年 | 239篇 |
1980年 | 194篇 |
1979年 | 206篇 |
1978年 | 163篇 |
1976年 | 162篇 |
1974年 | 157篇 |
1973年 | 159篇 |
1968年 | 169篇 |
1967年 | 201篇 |
1966年 | 174篇 |
1965年 | 166篇 |
1964年 | 161篇 |
1963年 | 155篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
951.
Journal of Material Cycles and Waste Management - Material flow analysis (MFA) is a well-established tool for supporting decisions on nutrient management. This paper shows the importance of the... 相似文献
952.
Ümit H. Kaynar Seda Çınar Sermin Çam Kaynar Mehmet Ayvacıklı Tülin Aydemir 《Journal of Polymers and the Environment》2018,26(6):2300-2310
Nano-ZnO-chitosan bio-composite beads were prepared for the sorption of \({\text{UO}}_{2}^{{2+}}\) from aqueous media. The resulting nano-ZnO/CTS bio-composite beads were characterized by TEM, XRD etc. The sorption of \({\text{UO}}_{2}^{{2+}}\) by bio-composite beads was optimized using RSM. The correlation between four variables was modelled and studied. According to RSM data, correlation coefficients (R2?=?0.99) and probability F-values (F?=?2.24?×?10??10) show that the model fits the experimental data well. Adsorption capacity for nano-ZnO/CTS bio-composite beads was obtained at 148.7 mg/g under optimum conditions. The results indicate that nano-ZnO/CTS bio-composite beads are appropriate for the adsorption of \({\text{UO}}_{2}^{{2+}}\) ions from aqueous media. Also, the suitability of adsorption values to adsorption isotherms was researched and thermodynamic data were calculated. 相似文献
953.
Emmanuel O. Ogunsona Amandine Codou Manjusri Misra Amar K. Mohanty 《Journal of Polymers and the Environment》2018,26(9):3574-3589
Natural fibers are limited in their use as reinforcement to commodity polymers. They cannot be used to reinforce engineering polymers due to their low thermal stability at high processing temperatures. This study presents an approach to successfully reinforce polyamides using a derivative of natural fibers as reinforcement without the effects of thermal degradation during melt processing. Biocarbon from miscanthus fibers was used to reinforce polyamide 6 up to 40 wt%. At 40 wt% filler content, the tensile and flexural strengths increased by 19.6 and 47% respectively in comparison to the neat polyamide. The moduli were also increased by 31.5 and 63.7% respectively. A maximum increase in impact strength of 43.7% was achieved at 20 wt% biocarbon loading. The morphology of the tensile fractured samples showed stretched polyamide ligaments attached to the biocarbon particles, indicating the presence of interaction between filler and matrix. Interestingly, more bonded interfaces were observed between the polyamide and biocarbon particles with increasing biocarbon content possibly stemming from increased biocarbon surfaces with functional groups. These composites show great potential to substitute in part or whole, some particulate filled polyamides currently used in the automotive industry. 相似文献
954.
Birinchi Bora Arun Kumar O. S. Sastry Renu Dahiya Manander Bangar Takumi Takashima 《International Journal of Green Energy》2016,13(6):580-584
The effect of air mass (AM) on the performance of multi-crystalline silicon (m-Si), amorphous silicon (a-Si), and hetero-junction with intrinsic thin layer (HIT)-technology-based photovoltaic (PV) modules are evaluated for representative day of four seasons during the year 2011 for composite climate of India. To find the best performing PV module technology with respect to AM at the site, annual energy yields and performance ratio against different AM bands (AM 1–4.5) are plotted. It is found that HIT modules perform better than m-Si and a-Si at each AM band. Annual energy yields for all three technologies decrease with increasing order of AM bands. The performance ratio for HIT and m-SI modules initially increases and then decreases with increasing order of AM bands. However, for a-Si modules, the performance ratio decreases with increasing order of the AM bands. 相似文献
955.
Seyfi Polat Ahmet Uyumaz Emre Yilmaz Tolga Topgül H. Serdar Yücesu 《International Journal of Green Energy》2016,13(1):63-70
EGR is one of the most significant strategies for reducing especially nitrogen oxides (NOx) emissions from internal combustion engines. The thermal efficiency of spark ignition engines is lower than compression ignition engines because of its lower compression ratio. If the compression ratio is increased to obtain higher thermal efficiency, there may be a knocking tendency in spark ignition engines. EGR can be used in order to reduce NOx emissions and avoid knocking phenomena at higher compression ratios. In-cylinder temperature at the end of combustion is decreased and heat capacity of fresh charge is increased when EGR applied. Besides EGR, spark timing is another significant parameter for reducing exhaust emissions such as nitrogen oxides, and unburned hydrocarbon (UHC). In this study the effects of EGR and spark timing on spark ignition engine were investigated numerically. KIVA codes were used in order to model combustion process. The combustion process has been modeled for a single cylinder, four stroke and gasoline direct injection (GDI) spark ignition engine. The results showed that in-cylinder pressure and heat release rate decrease as EGR ratio increase. In-cylinder pressure increases with the advancing of spark timing. Advancing spark timing increases the heat release rate and in-cylinder temperature. The simulation results also showed that EGR reduced exhaust gas temperature and NOx emissions. 相似文献
956.
Maartje J. Klapwijk Anna J. M. Hopkins Louise Eriksson Maria Pettersson Martin Schroeder Åke Lindelöw Jonas Rönnberg E. Carina H. Keskitalo Marc Kenis 《Ambio》2016,45(2):223-234
Intensifying global trade will result in increased numbers of plant pest and pathogen species inadvertently being transported along with cargo. This paper examines current mechanisms for prevention and management of potential introductions of forest insect pests and pathogens in the European Union (EU). Current European legislation has not been found sufficient in preventing invasion, establishment and spread of pest and pathogen species within the EU. Costs associated with future invasions are difficult to estimate but past invasions have led to negative economic impacts in the invaded country. The challenge is combining free trade and free movement of products (within the EU) with protection against invasive pests and pathogens. Public awareness may mobilise the public for prevention and detection of potential invasions and, simultaneously, increase support for eradication and control measures. We recommend focus on commodities in addition to pathways, an approach within the EU using a centralised response unit and, critically, to engage the general public in the battle against establishment and spread of these harmful pests and pathogens. 相似文献
957.
Martyn N. Futter Lars Högbom Salar Valinia Ryan A. Sponseller Hjalmar Laudon 《Ambio》2016,45(2):188-202
We present a framework for evaluating and communicating effects of human activity on water quality in managed forests. The framework is based on the following processes: atmospheric deposition, weathering, accumulation, recirculation and flux. Impairments to water quality are characterized in terms of their extent, longevity and frequency. Impacts are communicated using a “traffic lights” metaphor for characterizing severity of water quality impairments arising from forestry and other anthropogenic pressures. The most serious impairments to water quality in managed boreal forests include (i) forestry activities causing excessive sediment mobilization and extirpation of aquatic species and (ii) other anthropogenic pressures caused by long-range transport of mercury and acidifying pollutants. The framework and tool presented here can help evaluate, summarize and communicate the most important issues in circumstances where land management and other anthropogenic pressures combine to impair water quality and may also assist in implementing the “polluter pays” principle. 相似文献
958.
Marjut Rajasilta Mikael Elfving Jari Hänninen Päivi Laine Ilppo Vuorinen Jorma Paranko 《Ambio》2016,45(2):205-214
959.
960.