全文获取类型
收费全文 | 2264篇 |
免费 | 25篇 |
国内免费 | 25篇 |
专业分类
安全科学 | 73篇 |
废物处理 | 75篇 |
环保管理 | 331篇 |
综合类 | 487篇 |
基础理论 | 465篇 |
环境理论 | 3篇 |
污染及防治 | 606篇 |
评价与监测 | 134篇 |
社会与环境 | 121篇 |
灾害及防治 | 19篇 |
出版年
2023年 | 23篇 |
2022年 | 21篇 |
2021年 | 34篇 |
2020年 | 29篇 |
2019年 | 34篇 |
2018年 | 64篇 |
2017年 | 62篇 |
2016年 | 74篇 |
2015年 | 86篇 |
2014年 | 94篇 |
2013年 | 116篇 |
2012年 | 100篇 |
2011年 | 146篇 |
2010年 | 122篇 |
2009年 | 129篇 |
2008年 | 119篇 |
2007年 | 124篇 |
2006年 | 108篇 |
2005年 | 77篇 |
2004年 | 98篇 |
2003年 | 56篇 |
2002年 | 75篇 |
2001年 | 78篇 |
2000年 | 42篇 |
1999年 | 25篇 |
1998年 | 29篇 |
1997年 | 28篇 |
1996年 | 25篇 |
1995年 | 38篇 |
1994年 | 21篇 |
1993年 | 8篇 |
1992年 | 19篇 |
1991年 | 30篇 |
1990年 | 14篇 |
1989年 | 18篇 |
1988年 | 10篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 11篇 |
1981年 | 10篇 |
1979年 | 9篇 |
1970年 | 6篇 |
1969年 | 4篇 |
1965年 | 4篇 |
1960年 | 4篇 |
1958年 | 3篇 |
1954年 | 3篇 |
排序方式: 共有2314条查询结果,搜索用时 328 毫秒
581.
Among primates, group size is highly variable. The standard ecological model assumes that better predation avoidance as group
size increases favours living in larger groups, whereas increased travel costs and reduced net food intake due to within-group
competition for resources set the upper limit. Folivorous primates, however, tend to defy this generalisation in that some
live in small groups despite low costs of feeding competition. To resolve this ’folivore paradox’, it has been suggested that folivore group size is limited by social factors such as male
harassment or infanticide, or that females can disperse more easily and thus maintain group size near optimum levels. In this
paper, we examine the effects of group size on home range size, day-journey length, activity budget and diet in wild Thomas’s
langurs (Presbytis thomasi), which live in one-male multi-female groups with a limited life cycle. We examined only data from the stable middle tenure
phase when factors such as the strength of the breeding male or the way in which groups were formed did not influence ranging
and activities. During this phase, group size affected day-journey length and home range size, and had a minor effect on diet,
but did not influence time spent feeding or resting, allogrooming or birth rates. Hence the upper limit to group size during
the middle tenure phase in Thomas’s langurs is not set by feeding competition. The folivore paradox is not due to frequent
female dispersal in Thomas’s langurs. The timing of female dispersal is not as expected if it serves to keep group sizes near
the ecological optimum, and groups seem to be below this optimum. Instead, female reproductive success is presumably maximised
in small to mid-sized groups because larger groups show a clear trend to experience higher risk of take-over, often accompanied
by infanticide. Because females can redistribute themselves among nearby groups when groups reorganise each time a new male
starts up a new group, females can keep the group small. Thus, a social factor, risk of infanticide, seems to provide the
selective advantage to small group size in Thomas’s langurs.
Received: 29 July 1999 / Revised: 17 November 1999 / Accepted: 15 October 2000 相似文献
582.
Martin Volk Sven Lautenbach Hedwig van Delden Lachlan T. H. Newham Ralf Seppelt 《Environmental management》2010,46(6):834-849
This article analyses the benefits and shortcomings of the recently developed decision support systems (DSS) FLUMAGIS, Elbe-DSS,
CatchMODS, and MedAction. The analysis elaborates on the following aspects: (i) application area/decision problem, (ii) stakeholder
interaction/users involved, (iii) structure of DSS/model structure, (iv) usage of the DSS, and finally (v) most important
shortcomings. On the basis of this analysis, we formulate four criteria that we consider essential for the successful use
of DSS in landscape and river basin management. The criteria relate to (i) system quality, (ii) user support and user training,
(iii) perceived usefulness and (iv) user satisfaction. We can show that the availability of tools and technologies for DSS
in landscape and river basin management is good to excellent. However, our investigations indicate that several problems have
to be tackled. First of all, data availability and homogenisation, uncertainty analysis and uncertainty propagation and problems
with model integration require further attention. Furthermore, the appropriate and methodological stakeholder interaction
and the definition of ‘what end-users really need and want’ have been documented as general shortcomings of all four examples
of DSS. Thus, we propose an iterative development process that enables social learning of the different groups involved in
the development process, because it is easier to design a DSS for a group of stakeholders who actively participate in an iterative
process. We also identify two important lines of further development in DSS: the use of interactive visualization tools and
the methodology of optimization to inform scenario elaboration and evaluate trade-offs among environmental measures and management
alternatives. 相似文献
583.
Heli Routti Bert van Bavel Robert J. Letcher Augustine Arukwe Shaogang Chu Geir W. Gabrielsen 《Environmental pollution (Barking, Essex : 1987)》2009,157(8-9):2428-2434
The present study investigates the concentrations and patterns of organochlorine pesticides (OCPs) and their metabolites in liver and plasma of two ringed seal populations (Phoca hispida): lower contaminated Svalbard population and more contaminated Baltic Sea population. Among OCPs, p,p′-DDE and sum-chlordanes were the highest in concentration. With increasing hepatic contaminant concentrations and activities of xenobiotic-metabolizing enzymes, the concentrations of 3-methylsulfonyl-p,p′-DDE and the concentration ratios of pentachlorophenol/hexachlorobenzene increased, and the toxaphene pattern shifted more towards persistent Parlar-26 and -50 and less towards more biodegradable Parlar-44. Relative concentrations of the chlordane metabolites, oxychlordane and -heptachlorepoxide, to sum-chlordanes were higher in the seals from Svalbard compared to the seals from the Baltic, while the trend was opposite for cis- and trans-nonachlor. The observed differences in the OCP patterns in the seals from the two populations are probably related to the catalytic activity of xenobiotic-metabolizing enzymes, and also to differences in dietary exposure. 相似文献
584.
585.
586.
587.
588.
589.
Chantal Deden Kornelia Neveling Dimitra Zafeiropopoulou Christian Gilissen Rolph Pfundt Tuula Rinne Nicole de Leeuw Brigitte Faas Thatjana Gardeitchik Suzanne C. E. H. Sallevelt Aimee Paulussen Servi J. C. Stevens Esther Sikkel Mariet W. Elting Merel C. van Maarle Karin E. M. Diderich Nicole Corsten-Janssen Klaske D. Lichtenbelt Guus Lachmeijer Lisenka E. L. M. Vissers Helger G. Yntema Marcel Nelen Ilse Feenstra Wendy A. G. van Zelst-Stams 《黑龙江环境通报》2020,40(8):972-983
Objective
The purpose of this study was to explore the diagnostic yield and clinical utility of trio-based rapid whole exome sequencing (rWES) in pregnancies of fetuses with a wide range of congenital anomalies detected by ultrasound imaging.Methods
In this observational study, we analyzed the first 54 cases referred to our laboratory for prenatal rWES to support clinical decision making, after the sonographic detection of fetal congenital anomalies. The most common identified congenital anomalies were skeletal dysplasia (n = 20), multiple major fetal congenital anomalies (n = 17) and intracerebral structural anomalies (n = 7).Results
A conclusive diagnosis was identified in 18 of the 54 cases (33%). Pathogenic variants were detected most often in fetuses with skeletal dysplasia (n = 11) followed by fetuses with multiple major fetal congenital anomalies (n = 4) and intracerebral structural anomalies (n = 3). A survey, completed by the physicians for 37 of 54 cases, indicated that the rWES results impacted clinical decision making in 68% of cases.Conclusions
These results suggest that rWES improves prenatal diagnosis of fetuses with congenital anomalies, and has an important impact on prenatal and peripartum parental and clinical decision making. 相似文献590.
Maurike de Groot-van der Mooren Gert de Graaf Michel E Weijerman Mariette J. V Hoffer Jeroen Knijnenburg Anne-Marie M. F van der Kevie-Kersemaekers Angelique J. A Kooper Els Voorhoeve Birgit Sikkema-Raddatz Laura J. C. M van Zutven Malgorzata Ilona Srebniak Karin Huijsdens-van Amsterdam John J. M Engelen Dominique Smeets Anton H van Kaam Martina C Cornel 《黑龙江环境通报》2021,41(10):1351-1359