全文获取类型
收费全文 | 122篇 |
免费 | 0篇 |
国内免费 | 2篇 |
专业分类
安全科学 | 2篇 |
废物处理 | 6篇 |
环保管理 | 15篇 |
综合类 | 44篇 |
基础理论 | 18篇 |
污染及防治 | 24篇 |
评价与监测 | 7篇 |
社会与环境 | 8篇 |
出版年
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 2篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 10篇 |
2012年 | 5篇 |
2011年 | 4篇 |
2010年 | 8篇 |
2009年 | 10篇 |
2008年 | 6篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1995年 | 1篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1980年 | 2篇 |
1969年 | 1篇 |
1965年 | 1篇 |
1963年 | 2篇 |
1960年 | 1篇 |
1959年 | 2篇 |
1955年 | 3篇 |
1933年 | 2篇 |
1932年 | 3篇 |
1930年 | 1篇 |
1929年 | 1篇 |
1928年 | 1篇 |
1927年 | 1篇 |
1926年 | 1篇 |
1923年 | 3篇 |
1922年 | 1篇 |
1915年 | 2篇 |
1913年 | 2篇 |
排序方式: 共有124条查询结果,搜索用时 31 毫秒
91.
Katrin Strauss Holger Scharpenberg Robin M. Crewe Felix Glahn Heidi Foth Robin F. A. Moritz 《Behavioral ecology and sociobiology》2008,62(9):1523-1531
Queen pheromones interfere with worker reproduction in social insects. However, there is still an unresolved question as to
whether this pheromone acts as an “honest” signal for workers, giving a reliable indication of the queen’s reproductive value,
or as a suppressive agent, inhibiting worker reproduction independent of the queen’s reproductive capacity. In honeybees (Apis mellifera), the queen’s mandibular gland secretion, a mix of fatty acids and some aromatic compounds, is crucial for regulating the
reproductive division of labor in the colony inhibiting ovary development in workers. We quantified the mandibular gland secretions
of virgin, drone-laying, and naturally mated queens using gas chromatography to test whether the queens’ mating, ovary activation,
or the reproductive value for workers correlated with the composition of the secretion. Although the absolute amounts of the
“queen substance” 9-oxo-2(E)-decenoic acid (9-ODA) were similar among the three groups, the proportions of 9-ODA decreased
with increasing reproductive quality. Furthermore, the ratios of queen to worker compounds were similar in all three treatment
groups, irrespective of the reproductive capacity. A multivariate analysis including all six compounds could not separate
drone-laying queens from naturally mated ones, both with active ovaries but only the latter ensuring colony survival. We suggest
that the mandibular gland pheromones are unlikely to function as reliable indicators of queen reproductive value and rather
operate as an agent to suppress worker reproduction. This does not exclude the possibility that other “honest” pheromone signals
exist in the honeybee colony, but these would have to arise from other semiochemicals, which could be produced by both the
queen and the brood. 相似文献
92.
Gerson Freitas Silva Valente Regina Célia Santos Mendonça José Antonio Marques Pereira Leonardo Bonato Felix 《Journal of environmental science and health. Part. B》2013,48(4):355-361
Iron electrodes were used for electrocoagulation (EC) treatment of wastewater from a dairy plant. Electrolysis time, pH, current density and distance between electrodes were considered to assess the removal efficiency of chemical oxygen demand (COD), total solids (TS) and their fractions and turbidity. Samples were collected from the effluent of a dairy plant using a sampling methodology proportional to the flow. The treatments were applied according to design factorial of half fraction with two levels of treatments and three repetitions at the central point. The optimization of parameters for treating dairy industry effluent by electrocoagulation using iron electrodes showed that electric current application for 15 minutes, an initial sample pH close to neutral (pH 7.0) and a current density of 50 A . m?2 resulted in a significant reduction in COD by 58 %; removal of turbidity, suspended solids and volatile suspended solids by 95 %; and a final treated effluent pH of approximately 9.5. Negative consequences of the type of electrode used were the emergence of an undesirable color and an increase in the proportion of dissolved solids in the treated effluent. 相似文献
93.
Landscape multifunctionality: a powerful concept to identify effects of environmental change 总被引:2,自引:0,他引:2
Janine Bolliger Michèle Bättig Justus Gallati Andreas Kläy Michael Stauffacher Felix Kienast 《Regional Environmental Change》2011,11(1):203-206
The interdisciplinary concept of landscape multifunctionality provides a suitable platform to combine or disentangle effects
of multiple environmental stressors acting on the landscape. The concept allows mapping of trade-offs, synergies, and priority
conflicts between individual landscape functions, thus providing easily accessible, hands-on means to communicate findings
of environmental research to decision makers and society. This rapid communication provides an overview of current developments
and potential future research avenues in landscape multifunctionality. 相似文献
94.
M. Felix V. Perez-Puyana A. Romero A. Guerrero 《Journal of Polymers and the Environment》2017,25(1):91-100
Bioplastic materials from renewable polymers, like proteins, constitute a highly interesting field for important industrial applications such as packaging, agriculture, etc., in which thermo-mechanical techniques are increasingly being used. This study assesses bioplastic materials produced by injection from blends previously prepared in a batch mixer using various protein concentrates and isolates. A mixing time of 5 min has been selected in order to ensure correct homogenous blends. A comparison between different protein-based specimens was performed by dynamic mechanical thermal analysis, tensile strength, water uptake and transmittance tests. The comparison reveals that the protein nature and the percentage of plasticizer lead to bioplastics with different properties and, consequently, different applications. Protein concentrates and isolates, wastes and surpluses from the food industry, may be useful for producing bioplastics with suitable mechanical properties and processability, as well as biodegradability, by means of suitable mixing and injection moulding conditions. 相似文献
95.
Werth S Wagner HH Gugerli F Holderegger R Csencsics D Kalwij JM Scheidegger C 《Ecology》2006,87(8):2037-2046
Dispersal is a process critical for the dynamics and persistence of metapopulations, but it is difficult to quantify. It has been suggested that the old-forest lichen Lobaria pulmonaria is limited by insufficient dispersal ability. We analyzed 240 DNA extracts derived from snow samples by a L. pulmonaria-specific real-time PCR (polymerase chain reaction) assay of the ITS (internal transcribed spacer) region allowing for the discrimination among propagules originating from a single, isolated source tree or propagules originating from other locations. Samples that were detected as positives by real-time PCR were additionally genotyped for five L. pulmonaria microsatellite loci. Both molecular approaches demonstrated substantial dispersal from other than local sources. In a landscape approach, we additionally analyzed 240 snow samples with real-time PCR of ITS and detected propagules not only in forests where L. pulmonaria was present, but also in large unforested pasture areas and in forest patches where L. pulmonaria was not found. Monitoring of soredia of L. pulmonaria transplanted to maple bark after two vegetation periods showed high variance in growth among forest stands, but no significant differences among different transplantation treatments. Hence, it is probably not dispersal limitation that hinders colonization in the old-forest lichen L. pulmonaria, but ecological constraints at the stand level that can result in establishment limitation. Our study exemplifies that care has to be taken to adequately separate the effects of dispersal limitation from a limitation of establishment. 相似文献
96.
97.
The Use of Low-Level Jets by Migrating Birds 总被引:1,自引:0,他引:1
Birds flying at high altitudes have occasionally been observed above mountain areas and the open sea. For the first time
the regular occurrence of migrating birds flying within a low-level jet at heights of 5000 to almost 9000 m asl. have now
been verified by radar above the Negev desert in southern Israel. Tracks of rather large birds with wing-beat frequencies
of 5–6 Hz were measured to have horizontal flight speeds up to 50 m/s. Visual observations, seasonal occurrence, and wing-beat
frequencies allowed to associate them with small species of the order Ciconiiformes (mainly Ardeidae) and possibly with members
of the Laro-Limicolae group. These wading birds seem prone to continuing nocturnal migration into daytime under favorable
conditions and to make use of high wind speeds at sometimes extreme altitudes.
Received: 21 June 1999 / Accepted in revised form: 26 August 1999 相似文献
98.
99.
Paul Luchtenberg Felix Ehrlich Leon Asher Friedrich Drenckhahn 《Die Naturwissenschaften》1922,10(47):1010-1014
100.