全文获取类型
收费全文 | 10961篇 |
免费 | 123篇 |
国内免费 | 104篇 |
专业分类
安全科学 | 328篇 |
废物处理 | 505篇 |
环保管理 | 1415篇 |
综合类 | 1402篇 |
基础理论 | 2885篇 |
环境理论 | 4篇 |
污染及防治 | 3052篇 |
评价与监测 | 808篇 |
社会与环境 | 736篇 |
灾害及防治 | 53篇 |
出版年
2023年 | 56篇 |
2022年 | 123篇 |
2021年 | 103篇 |
2020年 | 80篇 |
2019年 | 91篇 |
2018年 | 174篇 |
2017年 | 167篇 |
2016年 | 256篇 |
2015年 | 191篇 |
2014年 | 276篇 |
2013年 | 800篇 |
2012年 | 353篇 |
2011年 | 513篇 |
2010年 | 405篇 |
2009年 | 457篇 |
2008年 | 526篇 |
2007年 | 541篇 |
2006年 | 464篇 |
2005年 | 408篇 |
2004年 | 373篇 |
2003年 | 411篇 |
2002年 | 365篇 |
2001年 | 532篇 |
2000年 | 347篇 |
1999年 | 208篇 |
1998年 | 157篇 |
1997年 | 145篇 |
1996年 | 154篇 |
1995年 | 178篇 |
1994年 | 136篇 |
1993年 | 111篇 |
1992年 | 135篇 |
1991年 | 124篇 |
1990年 | 142篇 |
1989年 | 137篇 |
1988年 | 100篇 |
1987年 | 91篇 |
1986年 | 74篇 |
1985年 | 98篇 |
1984年 | 100篇 |
1983年 | 95篇 |
1982年 | 90篇 |
1981年 | 76篇 |
1980年 | 62篇 |
1979年 | 71篇 |
1977年 | 55篇 |
1976年 | 50篇 |
1975年 | 55篇 |
1974年 | 53篇 |
1973年 | 55篇 |
排序方式: 共有10000条查询结果,搜索用时 437 毫秒
981.
982.
983.
Abstract: Although economic analysis can be used to argue for preservation of species and habitats, many natural assets represent inferior investments in society's asset portfolio. We demonstrate this for the case of ancient temperate rainforests and minke whales ( Balaenoptera acutorostrata ). For both rainforests and whales, we determined their value for harvest and balanced this against society's valuation of the preserved stock. For the market and nonmarket data available, we then determined how much rainforest and how many minke whales global society should keep in its asset portfolio. Although ecologists increasingly attempt to justify preservation of biological assets on economic grounds, we argue that this might be a dangerous approach to take. Ultimately, it may be necessary to reexamine the ethical foundations for conservation of nature and biodiversity, including the economist's use of utilitarianism. We suggest that the safe minimum standard approach may prove useful in practice. 相似文献
984.
Liesbeth Vossaert Imen Chakchouk Roni Zemet Ignatia B. Van den Veyver 《黑龙江环境通报》2021,41(10):1202-1214
Investigators have long been interested in the natural phenomenon of fetal and placental cell trafficking into the maternal circulation. The scarcity of these circulating cells makes their detection and isolation technically challenging. However, as a DNA source of fetal origin not mixed with maternal DNA, they have the potential of considerable benefit over circulating cell-free DNA-based noninvasive prenatal genetic testing (NIPT). Endocervical trophoblasts, which are less rare but more challenging to recover are also being investigated as an approach for cell-based NIPT. We review published studies from around the world describing both forms of cell-based NIPT and highlight the different approaches’ advantages and drawbacks. We also offer guidance for developing a sound cell-based NIPT protocol. 相似文献
985.
986.
987.
988.
989.
Blake T. Dotta Nirosha J. Murugan Lukasz M. Karbowski Robert M. Lafrenie Michael A. Persinger 《Die Naturwissenschaften》2014,101(2):87-94
During the first 24 h after removal from incubation, melanoma cells in culture displayed reliable increases in emissions of photons of specific wavelengths during discrete portions of this interval. Applications of specific filters revealed marked and protracted increases in infrared (950 nm) photons about 7 h after removal followed 3 h later by marked and protracted increases in near ultraviolet (370 nm) photon emissions. Specific wavelengths within the visible (400 to 800 nm) peaked 12 to 24 h later. Specific activators or inhibitors for specific wavelengths based upon Cosic’s resonant recognition model elicited either enhancement or diminishment of photons at the specific wavelength as predicted. Inhibitors or activators predicted for other wavelengths, even within 10 nm, were less or not effective. There is now evidence for quantitative coupling between the wavelength of photon emissions and intrinsic cellular chemistry. The results are consistent with initial activation of signaling molecules associated with infrared followed about 3 h later by growth and protein-structural factors associated with ultraviolet. The greater-than-expected photon counts compared with raw measures through the various filters, which also function as reflective material to other photons, suggest that photons of different wavelengths might be self-stimulatory and could play a significant role in cell-to-cell communication. 相似文献
990.
T. Colombo R. Santaguida A. Capasso F. Calzolari F. Evangelisti P. Bonasoni 《Atmospheric environment (Oxford, England : 1994)》2000,34(29-30)
The study concerning carbon dioxide measurements taken during the 1997, 1998 and 1999 summer campaigns at two different altitude stations and biospheric conditions are presented. The higher station (Mt. Cimone, 2165 m a.s.l.) is characterised by 360° free horizon and is located on a rocky mountain while the lower (Ninfa lake, 1550 m a.s.l.) is located inside the red spruce and beech forest. The different behaviour of CO2 at the two mountain stations has been registered. It shows the strong effect of nighttime soil emission and vegetation respiration on CO2 mixing ratio increases and of diurnal vegetative activity on CO2 concentration decreases at the lower measurement site. The baseline character of the higher measurement site has been confirmed by comparison of CO2 diurnal amplitudes recorded at the two stations. 相似文献