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41.
The recent interest in the thermoluminescence of quartz extracted from unfired building materials, such as mortar and concrete for dose reconstruction applications, led to the requirement of an accurate determination of the lifetime of the intermediate glow peaks in this mineral. The prediction of the lifetimes of these peaks is helpful in establishing the likely time range within which retrospective measurements can be carried out. These peaks, corresponding to intermediate energy levels, occur in the glow curve in the temperature range 150–250°C (heating rate 2°C/s). Lifetimes of 720±70 days and 580±70 years (at a temperature of 15°C) were derived for the two main peaks placed in the glow curve at approximately 150°C and 200°C, respectively, using the isothermal decay technique. These results as well as the estimated values of the trap parameters (thermal activation energy and frequency factor) have been compared with the data already available in the literature. 相似文献
42.
Ivan?Mu?ozEmail author Joan?Rieradevall Xavier?Doménech Lloren??Milà 《The International Journal of Life Cycle Assessment》2004,9(4):272-280
Goal, Scope and Background Gipuzkoa is a department of the Vasque Country (Spain) with a population of about 700,000 people. By the year 2000 approximately
85% of municipal solid waste in this area was managed by landfilling, and only 15% was recycled. Due to environmental law
restrictions and landfill capacity being on its limit, a planning process was initiated by the authorities. LCA was used,
from an environmental point of view, to assess 7 possible scenarios arising from the draft Plan for the 2016 time horizon.
Main Features In each scenario, 9 waste flows are analysed: rest waste, paper and cardboard, glass containers, light packaging, organic-green
waste, as well as industrial/commercial wood, metals and plastics, and wastewater sludge. Waste treatments range from recycling
to energy recovery and landfilling.
Results Recycling of the waste flows separated at the source (paper and cardboard, glass, light packaging, organic-green waste, wood
packaging, metals and plastics) results in net environmental benefits caused by the substitution of primary materials, except
in water consumption. These benefits are common to the 7 different scenarios analysed. However, some inefficiencies are detected,
mainly the energy consumption in collection and transport of low density materials, and water consumption in plastic recycling.
The remaining flows, mixed waste and wastewater sludge, are the ones causing the major environmental impacts, by means of
incineration, landfilling of partially stabilised organic material, as well as thermal drying of sludge. With the characterisation
results, none of the seven scenarios can be clearly identified as the most preferable, although, due to the high recycling
rates expected by the Plan, net environmental benefits are achieved in 9 out of 10 impact categories in all scenarios when
integrated waste management is assessed (the sum of the 9 flows of waste). Finally, there are no relevant differences between
scenarios concerning the number of treatment plants considered. Nevertheless, only the effects on transportation impacts were
assessed in the LCA, since the plant construction stage was excluded from the system boundaries.
Conclusions The results of the study show the environmental importance of material recycling in waste management, although the recycling
schemes assessed can be improved in some aspects. It is also important to highlight the environmental impact of incineration
and landfilling of waste, as well as thermal drying of sludge using fossil fuels. One of the main findings of applying LCA
to integrated waste management in Gipuzkoa is the fact that the benefits of high recycling rates can compensate for the impacts
of mixed waste and wastewater sludge.
Recommendations and Outlook Although none of the scenarios can be clearly identified as the one having the best environmental performance, the authorities
in Gipuzkoa now have objective information about the future scenarios, and a multidisciplinary panel could be formed in order
to weight the impacts if necessary. In our opinion, LCA was successfully applied in Gipuzkoa as an environmental tool for
decision making. 相似文献
43.
Background
Involvement of conservative molecular modules and cellular mechanisms in the widely diversified processes of eukaryotic cell morphogenesis leads to the intriguing question: how do similar proteins contribute to dissimilar morphogenetic outputs. Formins (FH2 proteins) play a central part in the control of actin organization and dynamics, providing a good example of evolutionarily versatile use of a conserved protein domain in the context of a variety of lineage-specific structural and signalling interactions. 相似文献44.
45.
A mechanism for the establishment of polar cell morphology is presented, based on the internal forces that the cytoskeletal
structures exert on the cell boundary. Cell shapes are determined by postulating that they correspond to the minimum of the
total energy of the system, which is the sum of the bending energy of the cell boundary and the potential energies of the
involved forces. Axisymmetrical cell shapes are considered, and it is assumed that the cytoskeletal structures exert an extensional
axial force and are involved in controlling the area of the cell boundary. The dependence of cell shapes on the axial force
is presented for different values of this area. The results show that, at increasing axial force, the cell undergoes a discontinuous
transition from an oval shape, exhibiting an equatorial mirror symmetry into a polar shape. The proposed mechanism is related
to previously documented specific effects of microtubule- and actin-modifying drugs on polar shapes of developing isolated
retinal photoreceptor cells.
Received: 28 January 1998 / Revised version: 25 July 1998 / Accepted: 29 July 1998 相似文献
46.
Ivan?H?StillEmail author Ananthalakshmy?K?Vettaikkorumakankauv Anthony?DiMatteo Ping?Liang 《BMC evolutionary biology》2004,4(1):16
Background
Examination of ancient gene families can provide an insight into how the evolution of gene structure can relate to function. Functional homologs of the evolutionarily conserved transforming acidic coiled coil (TACC) gene family are present in organisms from yeast to man. However, correlations between functional interactions and the evolution of these proteins have yet to be determined. 相似文献47.
Mikhail Krasavin Raivis Žalubovskis Aiga Grandāne Ilona Domračeva Petr Zhmurov 《Journal of enzyme inhibition and medicinal chemistry》2013,28(1):506-510
Abstract The hypothesis that sulfocoumarin acting as inhibitors of human carbonic anhydrase (CA, EC 4.2.1.1) cancer-associated isoforms hCA IX and – hCA XII is being able to also inhibit thioredoxin reductase was verified and confirmed. The dual targeting of two cancer cell defence mechanisms, i.e. hypoxia and oxidative stress, may both contribute to the observed antiproliferative profile of these compounds against many cancer cell lines. This unprecedented dual anticancer mechanism may lead to a new approach for designing innovative therapeutic agents. 相似文献
48.
Darja Duh Mirko Slovák Ana Saksida Katja Strašek Miroslav Petrovec Tatjana Avšič-Županc 《Biologia》2006,61(2):231-233
Dermacentor reticulatus ticks are recognized as the most important vectors of Babesia canis, the aetiological agent of canine babesiosis occurring throughout Europe. Vector competence of D. reticulatus for B. canis is well described and experimentally determined; however, by using molecular analysis it was proven so by one recent study
in Russia. Herein, the additional molecular evidence of B. canis infection in D. reticulatus ticks collected in Slovakia is provided. Using PCR followed by sequencing of distinctive amplicons we determined the presence
of Babesia canis canis in one of 100 tested adult ticks. Two zoonotic pathogens, Francisella tularensis and Coxiella burnetii, were previously isolated from D. reticulatus ticks in Slovakia. In our samples, we detected only the presence of F. tularensis. 相似文献
49.
50.
Continuous progress in empirical population genetics based on the whole‐genome polymorphism data requires the theoretical analysis of refined models in order to interpret the evolutionary history of populations with adequate accuracy. Recent studies focus prevalently on the aspects of demography and adaptation, whereas age structure (for example, in plants via the maintenance of seed banks) has attracted less attention. Germ banking, that is, seed or egg dormancy, is a prevalent and important life‐history trait in plants and invertebrates, which buffers against environmental variability and modulates species extinction in fragmented habitats. Within this study, we investigate the combined effect of germ banking and time‐varying population size on the neutral coalescent and particularly derive the allele frequency spectrum under some simplifying assumptions. We then perform an ABC analysis using two simple demographic scenarios—a population expansion and an instantaneous decline. We demonstrate the appreciable influence of seed banks on the estimation of demographic parameters depending on the germination rate with biases scaled by the square of the germination rate. In the more complex case of a population bottleneck, which comprises an instantaneous decline and an expansion phase, ignoring information on the germination rate denies reliable estimates of the bottleneck parameters via the allelic spectrum. In particular, when seeds remain in the bank over several generations, recent expansions may remain invisible in the frequency spectrum, whereas ancient declines leave signatures much longer than in the absence of seed bank. 相似文献