全文获取类型
收费全文 | 987篇 |
免费 | 20篇 |
国内免费 | 12篇 |
专业分类
安全科学 | 45篇 |
废物处理 | 45篇 |
环保管理 | 253篇 |
综合类 | 85篇 |
基础理论 | 254篇 |
污染及防治 | 225篇 |
评价与监测 | 65篇 |
社会与环境 | 33篇 |
灾害及防治 | 14篇 |
出版年
2023年 | 4篇 |
2022年 | 14篇 |
2021年 | 12篇 |
2020年 | 11篇 |
2019年 | 11篇 |
2018年 | 21篇 |
2017年 | 19篇 |
2016年 | 30篇 |
2015年 | 25篇 |
2014年 | 35篇 |
2013年 | 106篇 |
2012年 | 35篇 |
2011年 | 56篇 |
2010年 | 39篇 |
2009年 | 36篇 |
2008年 | 53篇 |
2007年 | 47篇 |
2006年 | 44篇 |
2005年 | 30篇 |
2004年 | 26篇 |
2003年 | 36篇 |
2002年 | 33篇 |
2001年 | 16篇 |
2000年 | 20篇 |
1999年 | 20篇 |
1998年 | 5篇 |
1997年 | 17篇 |
1996年 | 15篇 |
1995年 | 13篇 |
1994年 | 12篇 |
1993年 | 12篇 |
1992年 | 15篇 |
1991年 | 9篇 |
1990年 | 7篇 |
1989年 | 11篇 |
1988年 | 6篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 13篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1982年 | 15篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1974年 | 3篇 |
排序方式: 共有1019条查询结果,搜索用时 15 毫秒
101.
Douglas C. Daly 《Conservation biology》2002,16(4):1168-1169
102.
Mark J. Pettenati Margaret Berry Vandana Shashi J. Hartley Bowen Margaret Harper 《黑龙江环境通报》2001,21(6):435-440
The prenatal diagnosis of a complete trisomy of the long arm of chromosome 1 is reported. Major ultrasound findings included: nuchal thickening, bi-temporal narrowing, a single choroid plexus cyst, andmild ventriculomegaly. There was a mass in the chest and abdomen, pleural effusion, ascites and a hyperechoic bowel. Skin edema was present. The fetus died at 26 weeks' gestation. A literature review is presented of 17 de novo and two inherited cases with only trisomy 1q. Of note is the fact that 3/5 prenatally detected 1q trisomies have teratomas. A review of the literature reveals a dismal outcome fortrisomy 1q cases if the duplication involves bands 1q25→q32. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
103.
G. W. Uetz William J. McClintock Douglas Miller Elizabeth I. Smith Kristina K. Cook 《Behavioral ecology and sociobiology》1996,38(4):253-257
Males of the brush-legged wolf spider Schizocosa ocreata (Hentz) have conspicuously decorated forelegs used in courtship and agonistic displays. Approximately one in five juvenile
males has a missing or regenerating foreleg, and regeneration of a leg lost during development usually results in the absence
of a decorative tuft on that leg. The subsequent asymmetry in this male secondary character significantly decreases success
in both courtship of females and male-male agonistic interactions. Experimental removal of tufts from one leg of previously
successful symmetric males produces similar results. As a test for concomitant behavioral effects, female spiders were shown
video images of a courting male with symmetric tufts and the same video image altered to have asymmetric tufts. Female receptivity
to the asymmetric video image was lower. In contrast to fluctuating asymmetry resulting from developmental instability, leg
tuft asymmetry in S. ocreata most likely arises from a single event during ontogeny – possibly leg loss from an aggressive or predator encounter – and
may serve as a quality indicator in female mate choice.
Received: 27 July 1995/ Accepted after revision: 19 November 1995 相似文献
104.
Although palms are the most commonly harvested tree family in the world, they are susceptible to overexploitation, and many harvest schemes are not sustainable. We assessed the impact of leaf harvesting of the Asian palm, Livistona rotundifolia , in North Sulawesi, Indonesia, to determine the effect of harvest intensity on subsequent growth and to determine if current harvest practices are ecologically sustainable. We conducted experimental harvests of two intensities and compared results with a control. Leaf emergence, expansion, opening, and maturation were monitored for 1 year. Leaves in heavy and light harvest treatments grew and opened significantly faster than control leaves. Final leaf size was a function of harvest intensity: control leaves were larger (4.06 m) than light-harvest leaves (3.62 m) and heavy-harvest leaves (2.62 m). Census results for palms in harvested and unharvested areas indicated that palm density was twice as high and reproductive-sized palms were 10 times more common in the unharvested area. We judged current harvest practices to be nonsustainable. Recommendations for sustainable harvesting include reduction of harvest intensity and waste and preservation of reproductive-sized palms. 相似文献
105.
106.
John P Dwyer Douglas Wallace David R. Larsen 《Journal of the American Water Resources Association》1997,33(2):481-489
ABSTRACT: Following the Midwest flood of 1993, a study was initiated along a 39-mile segment of the Missouri River to determine if there was an association between woody corridors and levee stability. A systematic sample of levee failures revealed that primary levees which did not fail had a significantly wider woody corridor than failed levees. Analysis of the total inventory of failed levees revealed that as the width of the woody corridor decreased, the length of the levee failure increased. Number of levee failures and their severity of damage could be reduced if woody corridors were at least 300 feet wide. 相似文献
107.
108.
Margaret Gooch 《Local Environment》2005,10(1):5-19
This paper discusses findings of a study of catchment care volunteers drawn from the east coast of Queensland, Australia. Catchment volunteering includes individuals in not-for profit stewardship groups with a catchment focus. Catchment volunteering was experienced by participants as maintaining a balance of perspectives; developing/maintaining an identity; networking; learning; empowering; and sustainable. An illustrative model (the Outcome Space), representing a set of scales, shows the relationship between conceptions.
Results indicate that catchment volunteering offers many benefits to individuals and local communities. Although there were frustrations at times, many volunteers expressed deep levels of satisfaction about their volunteering experiences. Results suggest that satisfied volunteers are those that manage to balance volunteering with other aspects of their lives; identify strongly with some aspect of volunteering; enjoy learning from their volunteer experiences; and were willing and able to share and apply their new knowledge in a variety of ways. They also made friends with other volunteers; felt valued by others in the group, and believed that what they do is important. For these respondents, volunteering contributes richly to the fabric of their lives, providing meaning and satisfaction in routine activities, enhancing local communities and building sustainability. 相似文献
Results indicate that catchment volunteering offers many benefits to individuals and local communities. Although there were frustrations at times, many volunteers expressed deep levels of satisfaction about their volunteering experiences. Results suggest that satisfied volunteers are those that manage to balance volunteering with other aspects of their lives; identify strongly with some aspect of volunteering; enjoy learning from their volunteer experiences; and were willing and able to share and apply their new knowledge in a variety of ways. They also made friends with other volunteers; felt valued by others in the group, and believed that what they do is important. For these respondents, volunteering contributes richly to the fabric of their lives, providing meaning and satisfaction in routine activities, enhancing local communities and building sustainability. 相似文献
109.
Summary Larvae of Myrmeleon immaculatus in large pits captured both large and samll prey, while larvae in small pits captured only the small prey. Larvae in small pits did not respond to large ants, although they always responded by sand-flinging to small ants. Larvae in medium-sized pits often captured large ants only after prolonged and vigorous sand-flipping. Larvae in large pits usually captured large ants with relatively little sand-flipping. Pit enlargement and pit relocation in the laboratory were not significantly correlated with reduction of rations in the first 3 weeks after a pit was built. However, after a month without food, larvae on the average moved once every 10 days, built successively smaller pits, and moved longer distances before building a new pit. In the field pits were dug primarily in response to microclimatological factors and possibly edge-effects. The presence or absence of suitable prey at a site, per se, had no effect on whether or not a larva would dig a pit there. We conclude that these sit-and-wait predators have a relatively large repertoire of behavior that enhances their foraging success, and we contrast it with previously made optimal foraging models relating to pit locations, pit relocations, pit size and ant lion responses. 相似文献
110.