全文获取类型
收费全文 | 15913篇 |
免费 | 147篇 |
国内免费 | 117篇 |
专业分类
安全科学 | 333篇 |
废物处理 | 639篇 |
环保管理 | 1878篇 |
综合类 | 3640篇 |
基础理论 | 3633篇 |
环境理论 | 7篇 |
污染及防治 | 3969篇 |
评价与监测 | 1016篇 |
社会与环境 | 1015篇 |
灾害及防治 | 47篇 |
出版年
2022年 | 110篇 |
2021年 | 123篇 |
2019年 | 103篇 |
2018年 | 202篇 |
2017年 | 194篇 |
2016年 | 312篇 |
2015年 | 238篇 |
2014年 | 362篇 |
2013年 | 1080篇 |
2012年 | 401篇 |
2011年 | 613篇 |
2010年 | 471篇 |
2009年 | 552篇 |
2008年 | 633篇 |
2007年 | 673篇 |
2006年 | 602篇 |
2005年 | 506篇 |
2004年 | 529篇 |
2003年 | 518篇 |
2002年 | 487篇 |
2001年 | 623篇 |
2000年 | 391篇 |
1999年 | 292篇 |
1998年 | 184篇 |
1997年 | 205篇 |
1996年 | 222篇 |
1995年 | 230篇 |
1994年 | 230篇 |
1993年 | 218篇 |
1992年 | 195篇 |
1991年 | 205篇 |
1990年 | 199篇 |
1989年 | 169篇 |
1988年 | 168篇 |
1987年 | 154篇 |
1986年 | 153篇 |
1985年 | 149篇 |
1984年 | 169篇 |
1983年 | 167篇 |
1982年 | 172篇 |
1981年 | 144篇 |
1980年 | 132篇 |
1979年 | 123篇 |
1978年 | 134篇 |
1977年 | 115篇 |
1976年 | 103篇 |
1975年 | 107篇 |
1974年 | 118篇 |
1971年 | 98篇 |
1967年 | 101篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Tracy Nishikawa K S. Paybins J. A. Izbicki E. G. Reichard 《Journal of the American Water Resources Association》1999,35(1):133-142
ABSTRACT: To better understand the flow processes, solute-trans. port processes, and ground-water/surface-water interactions on the Santa Clara River in Ventura County, California, a 24-hour fluorescent-dye tracer study was performed under steady-state flow conditions on a 45-km reach of the river. The study reach includes perennial (uppermost and lowermost) subreaches and ephemeral subreaches of the lower Piru Creek and the middle Santa Clara River. The tracer-test data were used to calibrate a one-dimensional flow model (DAFLOW) and a solute-transport model (BLTM). The dye-arrival times at each sample location were simulated by calibrating the velocity parameters in DAFLOW. The simulations of dye transport indicated that (1) ground-water recharge explains the loss of mass in the ephemeral middle subreaches, and (2) ground-water recharge does not explain the loss of mass in the perennial uppermost and lowermost subreaches. The observed tracer curves in the perennial subreaches were indicative of sorptive dye losses, transient storage, and (or) photodecay - these phenomena were simulated using a linear decay term. However, analysis of the linear decay terms indicated that photodecay was not a dominant source of dye loss. 相似文献
992.
993.
G.J. Schürmann A. Algieri I.M. Hedgecock G. Manna N. Pirrone F. Sprovieri 《Atmospheric environment (Oxford, England : 1994)》2009,43(29):4424-4434
A modelling study with the on-line coupled Eulerian chemical-weather model WRF/Chem for the Southern Italian region around Cosenza (Calabria) was conducted to identify the influences of synoptic scale meteorology, local scale wind systems and local emissions on ozone concentrations in this orographically complex region. Four periods of 5–7 days were chosen, one from each season, which had wind pattern characteristics representative of typical local climatological conditions, in order to study the local versus non-local impacts on ozone transport and formation. To account for the complex terrain, the horizontal resolution of the smallest modelling domain was 3 km. Model results were compared with measurements to demonstrate the capability of the model to reproduce ozone concentrations in the region. The comparison was favourable with a mean bias of ?1.1 ppb. The importance of local emissions on ozone formation and destruction was identified with the use of three different emission scenarios. Generally the influence of regional emissions on the average ozone concentration was small. However during periods when mountain-sea wind systems were well developed and synoptic scale winds were weak, the influence of local emissions from the urban area was at its greatest. The maximum influence of local emissions on ozone concentrations was 18 ppb. 相似文献
994.
We conducted playback experiments to examine how parent tree swallows (Tachycineta bicolor) use nestling begging calls to distribute feedings to individuals within broods. In a first study, we used a paired-choice
test to determine if parents discriminated between the taped begging calls of nestlings deprived of food and those of nestlings
that had been recently fed. Our results showed that parents directed their first feeding attempt towards model nestlings near
speakers playing deprived calls significantly more often than to models near speakers playing fed calls. They also made more
feeding attempts overall to models with deprived calls. In the second study, we varied call rate and amplitude to examine
which call features parents might use to discriminate begging calls. Parents directed significantly more first feeding attempts
and more feeding attempts overall towards non-begging nestlings near speakers playing high call rates than to nestlings near
speakers playing low call rates. They did not, however, discriminate between calls differing in amplitude. Previous studies
have shown that parent birds use begging calls to regulate overall feeding rates to the brood. Our results suggest that parent
tree swallows also use begging calls when feeding individual nestlings and, in particular, prefer calls associated with increased
levels of nestling hunger.
Received: 14 February 2000 / Revised: 6 October 2000 / Accepted: 16 October 2000 相似文献
995.
本文描述中国、印度、菲律宾和斯里兰卡能源密集和污染型工业中可以引进的一些技术变革.当选择一种新的高能效和环境无害的工业技术时需要考虑的因素中包括现行技术的状态、前期费用、运行费用、设备效率、企业内部可供利用的技能水平.为了确认一种新技术是经济上可行的,也需要考虑许多外部因素:合理能源定价的存在,是否有适用的环境法规和激励机制到位,总体金融环境,经济体系的透明度等. 相似文献
996.
997.
998.
999.