全文获取类型
收费全文 | 16105篇 |
免费 | 142篇 |
国内免费 | 86篇 |
专业分类
安全科学 | 379篇 |
废物处理 | 669篇 |
环保管理 | 1875篇 |
综合类 | 2793篇 |
基础理论 | 4401篇 |
环境理论 | 6篇 |
污染及防治 | 4071篇 |
评价与监测 | 1073篇 |
社会与环境 | 973篇 |
灾害及防治 | 93篇 |
出版年
2022年 | 132篇 |
2021年 | 113篇 |
2020年 | 117篇 |
2019年 | 140篇 |
2018年 | 203篇 |
2017年 | 241篇 |
2016年 | 338篇 |
2015年 | 286篇 |
2014年 | 464篇 |
2013年 | 1223篇 |
2012年 | 506篇 |
2011年 | 710篇 |
2010年 | 622篇 |
2009年 | 593篇 |
2008年 | 679篇 |
2007年 | 723篇 |
2006年 | 605篇 |
2005年 | 520篇 |
2004年 | 531篇 |
2003年 | 516篇 |
2002年 | 492篇 |
2001年 | 653篇 |
2000年 | 484篇 |
1999年 | 264篇 |
1998年 | 177篇 |
1997年 | 210篇 |
1996年 | 213篇 |
1995年 | 242篇 |
1994年 | 240篇 |
1993年 | 184篇 |
1992年 | 201篇 |
1991年 | 187篇 |
1990年 | 211篇 |
1989年 | 187篇 |
1988年 | 154篇 |
1987年 | 163篇 |
1986年 | 156篇 |
1985年 | 159篇 |
1984年 | 148篇 |
1983年 | 142篇 |
1982年 | 126篇 |
1981年 | 121篇 |
1980年 | 115篇 |
1979年 | 126篇 |
1978年 | 101篇 |
1977年 | 113篇 |
1975年 | 87篇 |
1974年 | 88篇 |
1973年 | 98篇 |
1972年 | 87篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
271.
272.
J. Lelieveld P. Hadjinicolaou E. Kostopoulou C. Giannakopoulos A. Pozzer M. Tanarhte E. Tyrlis 《Regional Environmental Change》2014,14(5):1937-1949
The eastern Mediterranean and Middle East, a region with diverse socioeconomic and cultural identities, is exposed to strong climatic gradients between its temperate north and arid south. Model projections of the twenty-first century indicate increasing hot weather extremes and decreasing rainfall. We present model results, which suggest that across the Balkan Peninsula and Turkey climate change is particularly rapid, and especially summer temperatures are expected to increase strongly. Temperature rise can be amplified by the depletion of soil moisture, which limits evaporative cooling, prompted by the waning of large-scale weather systems that generate rain. Very hot summers that occurred only rarely in the recent past are projected to become common by the middle and the end of the century. Throughout the region, the annual number of heat wave days may increase drastically. Furthermore, conditions in the region are conducive for photochemical air pollution. Our model projections suggest strongly increasing ozone formation, a confounding health risk factor particularly in urban areas. This adds to the high concentrations of aerosol particles from natural (desert dust) and anthropogenic sources. The heat extremes may have strong impacts, especially in the Middle East where environmental stresses are plentiful. 相似文献
273.
V.S. Yaliwal P.G. Tewari S.Y. Adaganti 《International Journal of Sustainable Engineering》2014,7(3):269-282
Renewable and alternative fuels have numerous advantages compared with fossil fuels as they are renewable and biodegradable and provide food and energy security and foreign exchange savings besides addressing environmental concerns and socio-economic issues (Yaliwal et al. 2013. International Journal of Sustainable Engineering, doi:10.1080/19397038.2013.801530. Zhu et al. 2011a, Applied Thermal Engineering 31 (14–15): 2271–2278; Zhu et al. 2011b, Fuel 90: 1743-1750; Banapurmath, Tewari, and Hosmath 2008, Renewable Energy 33: 2007-2018; Banapurmath 2009, “Performance, Combustion and Emission Characteristics of a Single Cylinder Direct Injection CI Engine Operated on Dual Fuel Mode Using Honge Oil and Producer Gas.” PhD thesis, 1–195; Banapurmath et al. 2011, Waste and Biomass Valorization 2: 1–11). In this context, the main objective of the present work is to study methods of biofuel production such as Honge oil methyl ester (HOME) using a conventional transesterification process and bioethanol from the Calliandra calothyrsus shrub using a new pretreatment method known as hydrothermal explosion. Further, experimental investigations were carried out on a single-cylinder, four-stroke, direct-injection stationary diesel engine operating in a dual-fuel mode using HOME, bioethanol and producer gas combinations to determine its performance, combustion and emission characteristics. The performance of the dual-fuel engine was analyzed at optimized engine conditions. HOME-Bioethanol (BE) blends such as HOME+ 5% bioethanol (BE5), HOME+ 10% bioethanol (BE10) and HOME+ 15% bioethanol (BE15) were prepared by adding bioethanol to HOME (on volume basis) in different proportions ranging from 5 to 15% with an increment of 5%. In this present work, the effect of different BE blends on the performance of producer gas fuelled dual fuel engine was studied. Experimental investigation on dual fuel engine using BE5-Producer gas operation resulted in up to 4–9% increased brake thermal efficiency with decreased hydrocarbon (HC), carbon monoxide (CO) and marginally increased nitric oxide (NOx) emission levels compared to HOME-Producer gas, BE10-producer gas and BE15-producer gas mode of operation. However, it was observed that, the overall performance of BE-producer gas operation was found to be lower compared to diesel-producer gas operation. 相似文献
274.
P. A. Zadubrovskiy I. V. Zadubrovskaya M. A. Potapov O. F. Potapova V. I. Evsikov 《Russian Journal of Ecology》2016,47(1):82-87
Demographic structure and its seasonal dynamics have been studied in colonies of narrow-skulled voles (Lasiopodomys gregalis Pall.) in Northern Kulunda. Three types of colonies have been distinguished: (I) true colonies (large, complex families), (II) simple families (nuclear or incomplete), and (III) all-male colonies. Changes in their sex, age, and functional composition (based on animal migration activity) during the breeding season have been analyzed. 相似文献
275.
N. P. Korablev M. P. Korablev P. N. Korablev I. L. Tumanov 《Russian Journal of Ecology》2016,47(3):289-295
A comparative analysis of epigenetic variation has been performed in nine European populations and population groups of the American mink. It has been shown that differentiation of samples in nonmetric characters is due mainly to endogenous processes that have occurred in introduced populations in the course of colonization of new territory by the invasive species. Environmental factors have played a secondary role, with the influence of the geographic (latitudinal) origin of a given sample being considerable and stronger than that of macroclimatic factors. 相似文献
276.
Relationships between stem diameter and phytomass of trees and their parts (single- and multistemmed growth forms) have been studied at different altitudinal levels of the present-day upper treeline ecotone on the Iremel’ Massif, the Southern Urals. The time course of changes in the structure and phytomass of birch–spruce stands during the past centuries has been reconstructed. It is shown that the expansion of forests to the mountains in this period has occurred against the background of rise in summer and winter temperatures and increase in the amount of solid precipitation in the Southern Urals. 相似文献
277.
L. P. Agulova N. S. Moskvitina N. P. Bol’shakova L. B. Kravchenko N. V. Ivanova V. N. Romanenko 《Russian Journal of Ecology》2016,47(5):460-466
The dynamics and correlations of ecophysiological parameters have been studied in two spatially separated multispecies communities of murine rodents and ixodid tick larvae and nymphs that parasitize them. It has been shown that all the processes under consideration have nonstationary, oscillatory dynamics. The long-term dynamics of connectivity of ecophysiological characteristics within communities and their synchronization by weather–climatic factors are, by nature, wavelike processes of transitions between the states with stronger and weaker linkage between parameters, which, along with nonstationarity, can contribute to the maintenance of stability and integrity of communities. 相似文献
278.
E. S. Zakharov V. M. Safronov L. P. Koryakina N. N. Smetanin 《Russian Journal of Ecology》2016,47(4):392-398
The population of foxes in the central regions of Yakutia has grown by a factor of four to five during the period from 2000 to 2011–2012, following an increase in the abundance of voles from the genus Microtus. A total of 130 carcasses of foxes taken in 2007–2012 have been examined. Age- and sex-related variation in morphological features has been described. The demographic structure of the population has been studied by estimating animal age from annual layers in the recording structures. Changes in female fertility and involvement in reproduction depending on age and feeding conditions have been analyzed. Changes in the composition of fox diet caused by long-term population depression in the mountain hare and their effect on the dynamics of fox abundance have been revealed. Age- and sex-related characteristics of the condition factor in foxes and sex-related differences in their dietary preferences have been demonstrated. 相似文献
279.
280.