全文获取类型
收费全文 | 4138篇 |
免费 | 34篇 |
国内免费 | 21篇 |
专业分类
安全科学 | 76篇 |
废物处理 | 282篇 |
环保管理 | 304篇 |
综合类 | 431篇 |
基础理论 | 848篇 |
环境理论 | 7篇 |
污染及防治 | 1545篇 |
评价与监测 | 415篇 |
社会与环境 | 272篇 |
灾害及防治 | 13篇 |
出版年
2023年 | 54篇 |
2022年 | 117篇 |
2021年 | 184篇 |
2020年 | 76篇 |
2019年 | 69篇 |
2018年 | 152篇 |
2017年 | 163篇 |
2016年 | 234篇 |
2015年 | 120篇 |
2014年 | 243篇 |
2013年 | 388篇 |
2012年 | 281篇 |
2011年 | 301篇 |
2010年 | 227篇 |
2009年 | 162篇 |
2008年 | 226篇 |
2007年 | 270篇 |
2006年 | 193篇 |
2005年 | 156篇 |
2004年 | 109篇 |
2003年 | 93篇 |
2002年 | 91篇 |
2001年 | 53篇 |
2000年 | 41篇 |
1999年 | 26篇 |
1998年 | 16篇 |
1997年 | 11篇 |
1996年 | 13篇 |
1995年 | 15篇 |
1994年 | 11篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1985年 | 2篇 |
1982年 | 2篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1970年 | 2篇 |
1967年 | 4篇 |
1966年 | 4篇 |
1965年 | 2篇 |
1964年 | 5篇 |
1962年 | 3篇 |
1959年 | 4篇 |
1958年 | 15篇 |
1957年 | 5篇 |
1955年 | 2篇 |
排序方式: 共有4193条查询结果,搜索用时 913 毫秒
471.
Montserrat Bacardit Lluís Camarero 《Atmospheric environment (Oxford, England : 1994)》2010,44(4):582-595
The chemistry of high mountain snowpacks is a result of the long-range atmospheric transport and deposition of elements. Pyrenean snowpacks contain information about the fluxes of elements over SW Europe in winter. Here we analysed Al, Ti, Mn, Fe, Ni, Cu, Zn, As, Se, Cd and Pb in the 2004–05 winter snowpack in the Central Pyrenees, at an altitude range of 1820–3200 m a.s.l. Ni, As, Se and Cd were not detected in most cases. The concentrations of the remaining elements were comparable to those found in other high mountain areas in Europe and North America considered representative of regional background of atmospheric deposition in populated areas. In contrast, our measurements were higher than those of polar areas, which represent the global background. Single measurements of concentrations and snow accumulation were subject to considerable spatial variability, which may be attributable to strong wind drift and other post-depositional processes. The major ions chemistry of the snow indicated three possible origins for the solutes: terrigenous dust, sea salt spray and polluting S and N aerosols. We found no association between Cu, Zn and Pb and any of these possible sources. This observation therefore indicates that these elements were not preferentially bound to any particular kind of aerosol. Snow collected at altitudes of up to 2050 m a.s.l. presented higher concentrations of several elements than snow above this altitude, thereby indicating a local influence. Snow collected above 2300 m a.s.l. was therefore more representative of broad regional inputs. At these higher altitudes, snow was not enriched in Al, Ti, Mn, Fe or As compared with the composition of the upper continental crust and the local lithology, and these elements (except Mn) appeared almost exclusively in the particulate fraction. This observation indicates that Al, Ti, Mn, Fe and As were present mainly as part of dust particles of terrigenous origin. In contrast, Cu, Zn, and Pb presented medium to high enrichment factors and showed a higher proportion of soluble forms, thereby indicating their polluting character. 相似文献
472.
As resource conservation is an imperative for sustainable development, it is crucial to achieve a deeper understanding of the factors involved in people's decisions to recycle. This is even more so because the level of environmental concern is usually higher than the level of ecological behaviours. In this paper we take this fact as indicating that decision-making regarding conservation behaviours happens in the context of an internal debate where contradictory ideas are weighed up and the possibility of ambivalence arises. The main aim of this paper is therefore to explore how contradiction and ambivalence impact upon the attitudes, intentions and pro-ecological behaviours of the private sphere. The paper focuses specifically on the separation and deposition of metal cans, and compares the predictive capacity of beliefs, attitudes and intentions for two groups of respondents – one with a high and another with a low level of ambivalence, as assessed with a direct measure. The role of personal identity and the influence of structural constraints are also explored. Results demonstrate a clear moderating effect of experienced ambivalence, and show how beliefs, particularly negative ones, present a higher predictive capacity of the attitude in the high-ambivalence group, and personal identity plays a relevant role in predicting behaviour in both groups. We discuss the importance of pursuing the study of ambivalence when analysing decision-making in the conservation area. 相似文献
473.
Romina P. Pizzolitto María R. Armando Mariana Combina Lilia R. Cavaglieri Ana M. Dalcero Mario A. Salvano 《Journal of environmental science and health. Part. B》2013,48(10):933-941
In this study the aflatoxin B1 (AFB1) removal capacity, the tolerance to salivary and gastrointestinal conditions, autoaggregation and coaggregation with pathogenic bacteria of Saccharomyces cerevisiae strains isolated from broiler feces, were evaluated. Only four of twelve isolated strains were identified as Saccharomyces cerevisiae using molecular techniques. The results obtained in AFB1 binding studies indicated that the amount of AFB1 removed was both strain and mycotoxin-concentration dependent. Therefore, a theoretical model was applied in order to select the most efficient strain to remove AFB1 in a wide range of mycotoxin concentration. The results indicated that S. cerevisiae 08 and S. cerevisiae 01 strains were the most efficient microorganisms in the mycotoxin removal. Viability on simulated salivary and gastrointestinal conditions was investigated and S. cerevisiae 08 strain showed the best results, achieving 98% of total survival whereas S. cerevisiae 01 reached only 75%. Autoaggregation and coaggregation assays showed S. cerevisiae 08 as the most appropriate strain, mainly because it was the unique strain able to coaggregate with the four bacterial pathogens assayed. Consequently, S. cerevisiae 08 is the best candidate for future in vivo studies useful to prevent aflatoxicosis. Further quantitative in vitro and in vivo studies are required to evaluate the real impact of yeast-binding activity on the bioavailability of AFB1 in poultry. However, this study could be useful in selecting efficient strains in terms of AFB1 binding and provide an important contribution to research into microorganisms with potential probiotic effects on the host. 相似文献
474.
J Rivas E Rodríguez F J Beltrán J F García-Araya P Alvarez 《Journal of environmental science and health. Part. B》2001,36(3):317-330
Simazine, [2-chloro, 4,6-bis(ethylamino)-1,3,5-s-triazine], a common herbicide typically found in surface and ground water was ozonised by using catalytic amounts of Mn(II) and Fe(II). An optimum value for metal concentration was found in the process. Some inhibition of the simazine degradation rate was observed when these metals were added above the optimum concentration. The pH of the reaction media played a significant role in the simazine oxidation rate. Thus, an increase in simazine conversion was observed when the pH was raised from 5 to 9. However, the catalytic effect of added manganese was negligible at the highest pH used in this study (pH 9). The beneficial influence of Fe(II) was also observed when utilising the combination of ozone and hydrogen peroxide. Contrarily, Mn(II) presented a negative influence on simazine conversion when using this oxidation technology. 相似文献
475.
Variation of the amplification effect of burrows of the leptodactylid frog Eupsophus emiliopugini on conspecific calls generated externally was investigated. Advertisement calls broadcast through a loudspeaker placed in
the vicinity of a burrow were monitored with small microphones positioned inside and outside the cavity. For 150 presentations
of calls of 15 individuals in 12 burrows, 134 were amplified and 16 were attenuated (range –6–13 dB). The fundamental resonant
frequency of burrows, measured with broadcast noise and pure tones, averaged 814 Hz (range 302–1361 Hz) and covaried with
burrow length. The dominant frequency of the calls of burrow occupants (average 1062 Hz, range 636–1459 Hz) was not correlated
with the fundamental resonant frequency of these cavities. In burrows with low resonant frequencies, externally broadcast
calls with high dominant frequencies were attenuated, or amplified to a lower extent than calls with lower dominant frequencies.
The dominant frequencies of the calls experienced shifts towards the burrows’ fundamental resonant frequencies. The amplification
of calls inside burrows of E. emiliopugini exhibits manifest variability, with considerable potential for facilitating acoustic interactions in this species.
Received: 18 July 1999 / Received in revised form: 19 July 1999 / Accepted: 25 July 1999 相似文献
476.
M. Rifé J. Mallolas C. Badenas B. Tazón M. Rodríguez Miguélez T. Pàmpols A. Sànchez M. Milà 《黑龙江环境通报》2002,22(6):459-462
An Erratum has been published for this article in Prenatal Diagnosis 23 (9), 2003, 771. Fragile X syndrome (SFX) is the commonest form of inherited mental retardation. Due to the highly variable phenotype clinical diagnosis is complicated. In nearly all cases, the disorder is caused by expansion of a CGG-repeat in the 5′-untranslated region of the FMR1 (fragile X mental retardation-1) gene. We have evaluated the feasibility, efficiency and costs of two methodologies in order to develop a simple test to screen large populations: PCR and fragile X mental retardation-1 protein (FMRP) immunodetection. We studied 100 newborn males using PCR and immunodetection (26.91 Euro). All but one amplified the CGG repeat of the FMR1 gene within the normal size range. The sample that failed to amplify showed only 28% of FMRP expression by immunodetection study; both results indicated an affected male. A further 100 males were studied only by polymerase chain reaction (PCR) (7.8 Euro); all of them amplified within the normal size range. Both methodologies, PCR and immunodetection, are feasible for screening large populations, PCR being the most suitable, economical and less time-consuming. However, it is advisable to keep slides for immunodetection when PCR fails or the external control shows no amplification. Early detection of SFX-affected individuals would represent a great benefit for their maximum social integration, due to appropriate treatment and early stimulation and would permit a cascade screening in their pedigree. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
477.
478.
Alexandra Bächtold Estevão Alves-Silva Lucas A. Kaminski Kleber Del-Claro 《Die Naturwissenschaften》2014,101(11):913-919
Ovipositing adult females of myrmecophilous lycaenids are expected to select plants based on ant presence in order to maximize the survivorship of immature stages. Usually, larvae feed ants with honey-like solutions and, in turn, ants ward off parasitoids. Nonetheless, a rarely investigated approach is whether ant partners can also extend their protective behavior towards lycaenids eggs. Here, we investigated the ant-related oviposition pattern of Allosmaitia strophius and Rekoa marius; then, we compared egg parasitism according to the presence of ants. Lycaenid oviposition and egg parasitism (in percent) were experimentally compared in ant-present and ant-excluded treatments. The study plant, Heteropterys byrsonimifolia, is an extrafloral nectaried shrub which supports several ant species. We sampled 280 eggs, of which 39.65 % belonged to A. strophius and 60.35 % to R. marius. Both lycaenids eggs were significantly more abundant on branches with ants, especially those with Camponotus crassus and Camponotus blandus, two ant species known to attend to lycaenids. A. strophius and R. marius parasitism was 4.5- and 2.4-fold higher, respectively, in ant-present treatments, but the results were not statistically significant. Our study shows that ant-mediated host plant selection in lycaenids might be much more widespread than previously thought, and not restricted to obligate myrmecophilous species. Tending ants may be inefficient bodyguards of lycaenid eggs, because unlike larvae which release sugared liquids, eggs do not offer obvious rewards to ants. Ants can ward off parasitoids of larvae, as observed elsewhere, but our findings show that positive ant–lycaenid interactions are conditional and depend on immature ontogeny. 相似文献
479.
Dr Isabel Lorda-Sánchez Dan Diego-Alvarez Carmen Ayuso Marta Rodríguez de Alba Maria Jose Trujillo Carmen Ramos 《黑龙江环境通报》2005,25(10):934-938
Balanced reciprocal translocation is one of the known causes of recurrent spontaneous abortions. Cytogenetic studies of unbalanced miscarriages are difficult due to the growth failure of early loss and usually macerated abortions. We present a molecular study of an abortion in which the father carries a balanced reciprocal translocation t(2;17)(q32.1;q24.3) using QF-PCR and CGH techniques. DNA analysis showed the presence of a trisomy 2 due to a 3:1 interchange segregation. Recombinant events could also be investigated by comparing DNA samples from the family. We propose QF-PCR in addition to CGH as an efficient diagnostic method to improve our knowledge of unbalanced offspring in balanced translocation carriers. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
480.
Karen Hardy Stephen Buckley Matthew J. Collins Almudena Estalrrich Don Brothwell Les Copeland Antonio García-Tabernero Samuel García-Vargas Marco de la Rasilla Carles Lalueza-Fox Rosa Huguet Markus Bastir David Santamaría Marco Madella Julie Wilson ángel Fernández Cortés Antonio Rosas 《Die Naturwissenschaften》2012,99(8):617-626
Neanderthals disappeared sometime between 30,000 and 24,000?years ago. Until recently, Neanderthals were understood to have been predominantly meat-eaters; however, a growing body of evidence suggests their diet also included plants. We present the results of a study, in which sequential thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) were combined with morphological analysis of plant microfossils, to identify material entrapped in dental calculus from five Neanderthal individuals from the north Spanish site of El Sidrón. Our results provide the first molecular evidence for inhalation of wood-fire smoke and bitumen or oil shale and ingestion of a range of cooked plant foods. We also offer the first evidence for the use of medicinal plants by a Neanderthal individual. The varied use of plants that we have identified suggests that the Neanderthal occupants of El Sidrón had a sophisticated knowledge of their natural surroundings which included the ability to select and use certain plants. 相似文献