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51.
Predation of arthropods by southern bearded sakis (Chiropotes satanas) in Eastern Brazilian Amazonia
Bearded sakis are seed predators, but are also known to consume arthropods. This is the first detailed report of arthropod predation in southern bearded sakis (Chiropotes satanas). Two groups were monitored-one in continuous forest, and one on a small island-between January 2003 and February 2004. The arthropod prey included spiders and six insect orders. Island group members spent more time foraging for arthropods (3.8% vs. 2.6% of activity time) but ingested less prey (3.7% vs. 4.6% of feeding time). Arthropods accounted for a small proportion of feeding records in most months, but there were occasional sharp peaks due to the exploitation of temporary agglomerations of insects. In November, arthropods accounted for 26.6% and 14.2% of the feeding records of the mainland and island groups, respectively. The results suggest that bearded sakis actively seek arthropods as a dietary supplement, but that they represent a minor resource during most of the year, even under conditions of intense habitat fragmentation (island group). 相似文献
52.
Gleyce Moreno Barbosa Marcela Teso Froes Maria Bernadete Silva Venicio Feo da Veiga Rosangela Maria de Araújo Soares André Luis Souza dos Santos Carla Holandino 《Bioelectromagnetics》2012,33(4):334-345
The literature shows that the effects of direct electric currents on biological material are numerous, including bactericidal, fungicidal, parasiticidal, and anti‐tumoral, among others. Non‐pathogenic trypanosomatids, such as Herpetomonas samuelpessoai, have emerged as important models for the study of basic biological processes performed by a eukaryotic cell. The present study reports a dose‐dependent anti‐protozoan effect of direct electric treatment with both cathodic and anodic current flows on H. samuelpessoai cells. The damaging effects can be attributable to the electrolysis products generated during electric stimulation. The pH of the cell suspension was progressively augmented from 7.4 to 10.5 after the cathodic treatment. In contrast, the anodic treatment caused a pH decrease varying from 7.4 to 6.5. Transmission electron microscopy analyses revealed profound alterations in vital cellular structures (e.g., mitochondrion, kinetoplast, flagellum, flagellar pocket, nucleus, and plasma membrane) after exposure to both cathodic and anodic current flows. Specifically, cathodic current flow treatment induced the appearance of autophagic‐like structures on parasite cells, while those submitted to an anodic current flow presented marked disorganization of plasma membrane and necrotic appearance. However, parasites treated in the intermediary chamber (without contact with the electrodes) did not present significant changes in viability or morphology, and no pH variation was detected in this system. The use of H. samuelpessoai as a biological model and the direct electric current experimental approach used in our study provide important information for understanding the mechanisms involved in the cytotoxic effects of this physical agent. Bioelectromagnetics 33:334–345, 2012. © 2011 Wiley Periodicals, Inc. 相似文献
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Patrick LJM Zeeuwen Jos Boekhorst Ellen H van den Bogaard Heleen D de Koning Peter MC van de Kerkhof Delphine M Saulnier Iris I van Swam Sacha AFT van Hijum Michiel Kleerebezem Joost Schalkwijk Harro M Timmerman 《Genome biology》2012,13(11):R101
Background
Recent advances in sequencing technologies have enabled metagenomic analyses of many human body sites. Several studies have catalogued the composition of bacterial communities of the surface of human skin, mostly under static conditions in healthy volunteers. Skin injury will disturb the cutaneous homeostasis of the host tissue and its commensal microbiota, but the dynamics of this process have not been studied before. Here we analyzed the microbiota of the surface layer and the deeper layers of the stratum corneum of normal skin, and we investigated the dynamics of recolonization of skin microbiota following skin barrier disruption by tape stripping as a model of superficial injury.Results
We observed gender differences in microbiota composition and showed that bacteria are not uniformly distributed in the stratum corneum. Phylogenetic distance analysis was employed to follow microbiota development during recolonization of injured skin. Surprisingly, the developing neo-microbiome at day 14 was more similar to that of the deeper stratum corneum layers than to the initial surface microbiome. In addition, we also observed variation in the host response towards superficial injury as assessed by the induction of antimicrobial protein expression in epidermal keratinocytes.Conclusions
We suggest that the microbiome of the deeper layers, rather than that of the superficial skin layer, may be regarded as the host indigenous microbiome. Characterization of the skin microbiome under dynamic conditions, and the ensuing response of the microbial community and host tissue, will shed further light on the complex interaction between resident bacteria and epidermis. 相似文献56.
Theoretical and empirical evidence suggests that avian females are able to manipulate the offspring sex ratio at birth. Although
mating with an attractive male may induce females to skew the sex ratio toward males, the balance between the benefits of
producing attractive sons and the costs of competing with other females for mates could vary with female age, a possibility
that had not been previously explored. In this paper we increment experimentally the attractiveness of males of the polygynous
spotless starling (Sturnus unicolor) by adding green plants to their nests, a trait involved in courtship, and look for female age-differential effects on offspring
primary sex ratio. Young and middle aged females produced more sons in experimental than in control nests, as expected, but
old females showed the opposite tendency. To explain this novel result, we speculate that older females are limited to produce
the most costly sex because the physiological drawbacks imposed by ageing reduce their ability to compete with younger ones
for the non-shareable resources offered by males. We discuss that this evolutionary scenario may be widespread in avian polygynous
systems. 相似文献
57.
Appel MH da Silveira RB Chaim OM Paludo KS Silva DT Chaves DM da Silva PH Mangili OC Senff-Ribeiro A Gremski W Nader HB Veiga SS 《Biochimica et biophysica acta》2008,1780(2):167-178
Brown spider bites are associated with lesions including dermonecrosis, gravitational spreading and a massive inflammatory response, along with systemic problems that may include hematological disturbances and renal failure. The mechanisms by which the venom exerts its noxious effects are currently under investigation. It is known that the venom contains a major toxin (dermonecrotic toxin, biochemically a phospholipase D) that can experimentally induce dermonecrosis, inflammatory response, animal mortality and platelet aggregation. Herein, we describe cloning, heterologous expression, purification and functionality of a novel isoform of the 33 kDa dermonecrotic toxin. Circular dichroism analysis evidenced correct folding for the toxin. The recombinant toxin was recognized by whole venom serum antibodies and by a specific antibody to a previously described dermonecrotic toxin. The identified toxin was found to display phospholipase activity and dermonecrotic properties. Additionally, the toxin caused a massive inflammatory response in rabbit skin dermis, evoked platelet aggregation, increased vascular permeability, caused edema and death in mice. These characteristics in combination with functional studies for other dermonecrotic toxins illustrate that a family of dermonecrotic toxins exists, and includes a novel member with high activity that may be useful for future structural and functional studies. 相似文献
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A biofilter treating alkylbenzene vapors was characterized for its optimal running conditions and kinetic parame-ters. Kinetics
of the continuous biofilter were compared to batch kinetic data obtained with biofilm samples as well as with defined microbial
consortia and with pure culture isolates from the biofilter. Both bacteria and fungi were present in the bioreactor. Five
strains were isolated. Two bacteria, Bacillus and Pseudomonas, were shown to be dominant, as well as a Trichosporon strain
which could, however, hardly grow on alkylbenzenes in pure culture. The remaining two strains were most often overgrown by
the other three organisms in liquid phase batch cultures μ
max, KS, KI values and biodegradation rates were calculated and compared for the difterent mixed and pure cultures. Since filter bed
acidification was observed during biofiltration studies reaching a pH of about 4, experiments were also undertaken to study
the influence of pH on performance of the different cultures. Biodegradation and growth were possible in all cases, over the
pH range 3.5–7.0 at appreciable rates, both with mixed cultures and with pure bacterial cultures. Under certain conditions,
microbial activity was even observed in the presence of alkylbenzenes down to pH 2.5 with mixed cultures, which is quite unusual
and explains the ability of the present biocatalyst to remove alkylbenzenes with high efficiency in biofilters under acidic
conditions. 相似文献
60.
Summary This paper describes the genetic transformation of the astaxanthin-producing yeast Phaffia rhodozyma with the cloning vector pGH-1. The plasmid replicates autonomously in this yeast, and the selection of transformants was possible by using both, the URA3 marker from Saccharomyces cerevisiae, and the kanamycin resistance (KmR) determinant from the bacterial transposon Tn903. 相似文献