首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   93篇
  免费   1篇
  国内免费   1篇
安全科学   2篇
废物处理   5篇
环保管理   1篇
综合类   34篇
基础理论   22篇
污染及防治   14篇
评价与监测   8篇
社会与环境   9篇
  2023年   2篇
  2021年   2篇
  2020年   2篇
  2019年   2篇
  2018年   1篇
  2017年   2篇
  2016年   3篇
  2015年   2篇
  2014年   4篇
  2013年   2篇
  2012年   7篇
  2011年   3篇
  2010年   3篇
  2009年   2篇
  2008年   7篇
  2007年   6篇
  2006年   3篇
  2005年   2篇
  2004年   2篇
  2003年   2篇
  2002年   2篇
  2001年   3篇
  2000年   3篇
  1998年   1篇
  1996年   3篇
  1995年   2篇
  1990年   1篇
  1987年   2篇
  1986年   1篇
  1979年   1篇
  1974年   1篇
  1972年   1篇
  1965年   1篇
  1964年   2篇
  1961年   2篇
  1960年   3篇
  1959年   1篇
  1957年   4篇
  1956年   1篇
  1943年   1篇
排序方式: 共有95条查询结果,搜索用时 31 毫秒
51.
We report on a live-born male with 46,XY/47,XY+4/47,XY,+6 mosaicism. Trisomy 4 mosaicism was detected by karyotyping chorionic villus samples (CVS) and was confirmed by the analysis of 16 metaphases obtained from cultured amniotic fluid cells. Eight metaphases were normal (46,XY), two had trisomy 4 (47,XY,+4), and two had trisomy 6 (47,XY,+6). Two postnatal chromosomal analyses of blood lymphocytes at birth and at the age of one week were normal. Chromosomal analysis of cultured skin fibroblasts from the right inguinal region at the age of 12 months revealed trisomy 4 (47,XY,+4) in 49 metaphases, trisomy 6 (47,XY,+6) in 2 metaphases, and a normal karyotype (46,XY) in 49 cells of the 100 analyzed metaphases, respectively. The main clinical findings consist of prenatal growth retardation, hypoplasia of the right side of the face, a dysplastic and posteriorly rotated right ear, a high vaulted palate, retrognathia, aplasia of the right thumb, hypoplasia of the fingernails, a deep sacral dimple, and patchy skin hypopigmentation of the right leg. When last seen at the age of 14 months, his development was nearly normal. Five patients with trisomy 4 mosaicism have been reported previously, but none with an additional trisomy 6 mosaicism. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
52.
Using platinum based catalytic converters, platinum is emitted with the exhaust gases and deposited on the roads, and in their vicinity (sewage treatment plants, rivers), which increases the platinum concentrations in aquatic eco-systems. To evaluate the platinum discharge from roads, the platinum concentration was measured in rainwater from a road with a traffic fre quency of 16,000 automobiles per day. The platinum content of the samples varies strongly dependent upon the previous dry period, and the intensity and duration of the rainfall. Platinum was measured in 18 run-off samples from various rainfall events. The maximum platinum concentrations showed values up to 1.1. μg/l. The median value was 15 ng/l. Analysis of a sample from one rainfall events shows that platinum has a well defined firstflush effect, similar to that of particular bound lead and copper. The good correlation between platinum and coarse suspended matter, coarse particular lead and copper indicates that platinum in road run-offs is frequently found to be particular bound. Under the assumption that the road has been completely washed off, the platinum deposition can be estimated to be 14 ng/(m2d).  相似文献   
53.
We report the diagnosis of amnion rupture sequence made by sonography and fetoscopy during the first trimester of gestation in a case of missed abortion. The investigation revealed a demised fetus with the characteristics of 9 weeks of development. The early fetus had an amnion adhesion at the tip of the nose and strands of amnion wrapped around the terminal phalanges of both feet. No defects in addition to the face and limb involvement were identified. The karyotype was normal: 46,XX. In the reported case, fetoscopy allowed confirmation of the sonographic diagnosis of an amnion rupture sequence in the first trimester of gestation and consequently helped to clarify the cause of abortion in this case of early fetal demise. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
54.
Phase space prediction is a feature selection method which triesto exploit non-linear dynamics of an underlying system. We describe and offer a critical reconsideration of this approach,discuss questions of whether non-linear methods are justified by the data, and apply them to ozone time series from single locations. Our main objectives are to obtain air quality forecasts in order to provide public health warnings and to provide an insight into the dynamics of the underlying system.Interestingly, comparable linear data sets (surrogates)have very similar structure and give similar predictionaccuracy to that of the ozone data. In this instance theredoes not appear to be any advantage to applying the phasespace approach to univariate time series.  相似文献   
55.
This article provides a perspective on nature-based solutions. First, the argument is developed that nature-based solutions integrate social and ecological systems. Then, theoretical considerations relating to relational values, multifunctionality, transdisciplinarity, and polycentric governance are briefly outlined. Finally, a conceptual model of the social–ecological system of nature-based solutions is synthesised and presented. This conceptual model comprehensively defines the social and ecological external and internal systems that make up nature-based solutions, and identifies theoretical considerations that need to be addressed at different stages of their planning and implementation The model bridges the normative gaps of existing nature-based solution frameworks and could be used for consistent, comprehensive, and transferable comparisons internationally. The theoretical considerations addressed in this article inform practitioners, policymakers, and researchers about the essential components of nature-based solutions. The conceptual model can facilitate the identification of social and ecological interconnections within nature-based solutions and the range of stakeholders and disciplines involved.  相似文献   
56.
57.
Regulations for the sealing of landfill sites require two independent sealing components. To satisfy this requirement, the combined capillary barrier was developed using impermeable sheeting placed between the capillary layer and the capillary block of the traditional capillary barrier. In this study, a numerical model is introduced based on hydraulic characteristics obtained by means of measurements of samples of capillary barrier materials. To make a comparison possible, samples of a laboratory investigated barrier were measured. Two laboratory experiments with a simple and a combined capillary barrier were repeated using the developed numerical model and good agreement between computed and measured results was found. Subsequently, the model was used for investigating the effect of failure of the artificial sheeting on the capillary barrier’s efficiency. The obtained results are presented and discussed.  相似文献   
58.
Over the next century, society will increasingly be confronted with the impacts of global change (e.g. pollution, land use changes, and climate change). Multiple scenarios provide us with a range of possible changes in socio-economic trends, land uses and climate (i.e. exposure) and allow us to assess the response of ecosystems and changes in the services they provide (i.e. potential impacts). Since vulnerability to global change is less when society is able to adapt, it is important to provide decision makers with tools that will allow them to assess and compare the vulnerability of different sectors and regions to global change, taking into account exposure and sensitivity, as well as adaptive capacity. This paper presents a method that allows quantitative spatial analyses of the vulnerability of the human-environment system on a European scale. It is a first step towards providing stakeholders and policy makers with a spatially explicit portfolio of comparable projections of ecosystem services, providing a basis for discussion on the sustainable management of Europe’s natural resources.
Marc J. MetzgerEmail: Phone: +31-317-482983Fax: +31-317-484839
  相似文献   
59.
Summary Mating in the bushcricket Metaplastes ornatus Ramme 1931 entails a number of peculiar genital couplings that precede the transfer of the large spermatophore. During these phase-I couplings, the male introduces his specially structured subgenital plate into the female's genital chamber, performs back-and-forth movements, and turns her genital chamber inside out when he withdraws, whereupon the female carefully cleans her everted genital chamber with her mouthparts. During the last coupling (phase II) the male's subgenital plate is not introduced but the large spermatophore, which averages 22% of a male's body weight, is transferred. Counts of sperm in the spermathecae of females suggested that the phase-I couplings, which occur prior to spermatophore transfer, function to remove, or at least to reduce, the sperm of a female's previous mates. The form of the keel of the male's subgenital plate, its position within the female's genital tract during phase-I couplings, and the back-and-forth movements suggest that the male may stimulate release of sperm from the female's spermatheca by a mechanism similar to fertilization as eggs pass through the genital chamber during oviposition.  相似文献   
60.
Summary The stridulatory sounds and movements produced by the females of various bushcricket species (Tettigonoidea: Phaneropteridae: Barbitistini) are compared with those of the males. Behavioral experiments are carried out to determine the significance of the female sounds in acoustic communication. Selection factors involved in the evolution of female stridulation are discussed. The morphological apparatus for sound production has evolved independently in males and females. Whereas males rub a toothed file on the underside of the left wing over the inner edge of the right wing, the plectrum, the females stridulate by rubbing a thickened vein on the underside of the left wing over modified spines on the upper surface of the right wing (Fig. 2). Similarly, the movements responsible for sound production are not homologous in males and females. In the male the audible closing movement is always preceded by wing opening, whereas the female in general initiates the closing movement when the wings are in the resting slightly opened position, and abruptly produces complete closure (Fig. 3, 4 and 5). The female responds to male singing by emitting one to several highly damped sound pulses each lasting less than one ms. The interval between the song of a conspecific male and this response is a very precise species-specific characteristic (Fig. 7). In species with male songs that are complicated in structure or continuous, the females respond only at specific time-after patticular markers in the song of the male. The time interval between male song and female response is an important criterion by which the male identifies conspecific female song (Fig. 8). Because the response delay of the female and corresponding neuronal time window in the male are distinct they may be important in species discrimination.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号