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71.
Clint Rhode Simo N. Maduna Rouvay Roodt‐Wilding Aletta E. Bester‐van der Merwe 《Animal genetics》2014,45(3):456-459
Haliotis midae is South Africa's most important aquaculture species. The reproduction cycle is currently not closed as many farms rely on wild‐caught broodstock for seed production. However, there is an increasing interest in genetic improvement in commercial stocks, with a growing number of producers implementing selective breeding strategies. High throughput commercial production and mass spawning make it difficult to maintain breeding records; therefore, mostly mass selection is practised. The high fecundity and unequal parental contributions also often lead to increased levels of inbreeding. This study therefore aimed to assess the genetic effects of such breeding practices on commercial populations of H. midae. Using microsatellite loci, the genetic properties of a wild, an F1 and an F2 population were estimated and compared. Although there was no significant loss of genetic diversity amongst the cultured populations in comparison with the wild progenitor population, there was low‐to‐moderate genetic differentiation between populations. Relatedness amongst the F2 population was significant, and the rate of inbreeding was high. The effective population size for the F2 (±50) was also comparatively small with respect to the wild (∞) and F1 (±470) populations. These results suggest that farms need to give caution to breeding practices beyond the first (F1) generation and aim to increase effective population sizes and minimise inbreeding to ensure long‐term genetic gain and productivity. This study also confirms the usefulness of population genetic analyses for commercial breeding and stock management in the absence of extensive pedigree records. 相似文献
72.
Genya Mitani Masato Sato Jeong IK Lee Nagatoshi Kaneshiro Miya Ishihara Naoshi Ota Mami Kokubo Hideaki Sakai Tetsutaro Kikuchi Joji Mochida 《BMC biotechnology》2009,9(1):17-11
Background
Although the clinical results of autologous chondrocyte implantation for articular cartilage defects have recently improved as a result of advanced techniques based on tissue engineering procedures, problems with cell handling and scaffold imperfections remain to be solved. A new cell-sheet technique has been developed, and is potentially able to overcome these obstacles. Chondrocyte sheets applicable to cartilage regeneration can be prepared with this cell-sheet technique using temperature-responsive culture dishes. However, for clinical application, it is necessary to evaluate the characteristics of the cells in these sheets and to identify their similarities to naive cartilage. 相似文献73.
MARTIN REICHARD MATEJ POLAČIK 《Biological journal of the Linnean Society. Linnean Society of London》2010,100(1):62-72
Allopatric populations separated by vicariance events are expected to evolve reproductive isolating mechanisms as a result of disparate selection pressures and genetic drift. The appearance of reproductive isolating mechanisms may vary across taxa with differences in the opportunity for mate choice, and may be asymmetrical. In addition, premating barriers may be affected by individual mating experience. We used choice and no‐choice experiments to investigate reproductive isolation between two allopatric (island and mainland) and colour‐differentiated populations of an African annual fish, Nothobranchius korthausae. Assortative mating under experimental conditions was limited and asymmetrical. Preference for sympatric males was only expressed in nonvirgin females from one population. Virgin fish from both populations mated indiscriminately. No difference in the number of eggs laid, fertilization rate and hatching success was detected in no‐choice experiments. All mating combinations produced viable offspring and no postmating barriers were detected in terms of the performance and fertility of F1 hybrids. Overall, we found little evidence for significant reproductive isolation, which is in contrast with the related killifish taxa in which assortative mating can be strong, even among allopatric populations with no colour differentiation. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 62–72. 相似文献
74.
Jiao GS Simo O Nagata M O'Malley S Hemscheidt T Cregar L Millis SZ Goldman ME Tang C 《Bioorganic & medicinal chemistry letters》2006,16(19):5183-5189
A series of mono-, di-, and tri-guanidinylated derivatives of neamine were prepared via selective guanidinylation of neamine. These molecules represent a novel scaffold as inhibitors of anthrax lethal factor zinc metalloprotease. Methods for the synthesis of these compounds are described, and structure-activity relationships among the series are analyzed. In addition, initial findings regarding the mechanism of LF inhibition for these molecules are presented. 相似文献
75.
76.
In most other studies the release of amino acid neurotransmitters and modulators in vitro has been studied mostly using labeled
preloaded compounds. For several reasons the estimated release may not reliably reflect the release of endogenous compounds.
The magnitudes of the release cannot thus be quite correctly estimated using radioactive labels. The basal and K+-evoked release of the neuroactive endogenous amino acids γ-aminobutyrate (GABA), glycine, taurine, glutamate and aspartate
was now studied in slices from the striatum from 7-day-old to 3-month-old mice under control (normoxic) and ischemic conditions.
The release of alanine, threonine and serine was assessed as control. GABA and glutamate release was much greater in 3-month-old
than in 7-day-old mice, whereas with taurine the situation was the opposite. Ischemia markedly enhanced the release of all
these three amino acids. The release of aspartate and glycine was markedly enhanced as well whereas no effects were discernible
in the release of glutamine, alanine, serine and threonine. K+ stimulation (50 mM) enhanced the release of GABA, glutamate, taurine, aspartate and glycine in most cases, except with taurine
in 3-month-old mice under the ischemic conditions and with aspartate in 7-day-old mice under the control conditions. K+ stimulation did not affect the release of glutamine, alanine, serine or threonine. The results on endogenous amino acids
are qualitatively similar to those obtained in our earlier experiments with labeled preloaded amino acids. In conclusion,
in developing mice only inhibitory taurine is released in such amounts that may counteract the harmful effects of excitatory
amino acids in ischemia. 相似文献
77.
Nimpaye H Njiokou F Njine T Njitchouang GR Cuny G Herder S Asonganyi T Simo G 《Parasite (Paris, France)》2011,18(2):171-179
In order to better understand the epidemiology of Human and Animal trypanosomiasis that occur together in sleeping sickness foci, a study of prevalences of animal parasites (Trypanosoma vivax, T. congolense "forest type", and T. simiae) infections was conducted on domestic animals to complete the previous work carried on T. brucei gambiense prevalence using the same animal sample. 875 domestic animals, including 307 pigs, 264 goats, 267 sheep and 37 dogs were sampled in the sleeping sickness foci of Bipindi, Campo, Doumé and Fontem in Cameroon. The polymerase chain reaction (PCR) based method was used to identify these trypanosome species. A total of 237 (27.08%) domestic animals were infected by at least one trypanosome species. The prevalence of T. vivax, T. congolense "forest type" and T. simiae were 20.91%, 11.42% and 0.34% respectively. The prevalences of 7 vivax and T. congolense "forest type" differed significantly between the animal species and between the foci (p < 0.0001); however, these two trypanosomes were found in all animal species as well as in all the foci subjected to the study. The high prevalences of 7 vivax and T congolense "forest type" in Bipindi and Fontem-Center indicate their intense transmission in these foci. 相似文献
78.
Turunen SM Lammi MJ Saarakkala S Koistinen A Korhonen RK 《Biomechanics and modeling in mechanobiology》2012,11(5):665-675
The objective of this study was to evaluate the effect of sample preparation on the biomechanical behaviour of chondrocytes.
We compared the volumetric and dimensional changes of chondrocytes in the superficial zone (SZ) of intact articular cartilage
and cartilage explant before and after a hypotonic challenge. Calcein-AM labelled SZ chondrocytes were imaged with confocal
laser scanning microscopy through intact cartilage surfaces and through cut surfaces of cartilage explants. In order to clarify
the effect of tissue composition on cell volume changes, Fourier Transform Infrared microspectroscopy was used for estimating
the proteoglycan and collagen contents of the samples. In the isotonic medium (300 mOsm), there was a significant difference
(p < 0.05) in the SZ cell volumes and aspect ratios between intact cartilage samples and cartilage explants. Changes in cell
volumes at both short-term (2 min) and long-term (2 h) time points after the hypotonic challenge (180 mOsm) were significantly
different (p < 0.05) between the groups. Further, proteoglycan content was found to correlate significantly (r
2 = 0.63, p < 0.05) with the cell volume changes in cartilage samples with intact surfaces. Collagen content did not correlate with cell
volume changes. The results suggest that the biomechanical behaviour of chondrocytes following osmotic challenge is different
in intact cartilage and in cartilage explant. This indicates that the mechanobiological responses of cartilage and cell signalling
may be significantly dependent on the integrity of the mechanical environment of chondrocytes. 相似文献
79.
C Wolff M Espetvedt AK Lind S Rintakoski A Egenvall A Lindberg U Emanuelson 《BMC veterinary research》2012,8(1):131
ABSTRACT: BACKGROUND: In the Nordic countries Denmark, Finland, Norway and Sweden, the majority of dairy herds are covered by disease recording systems, in general based on veterinary registration of diagnoses and treatments. Disease data are submitted to the national cattle databases where they are combined with, e.g., production data at cow level, and used for breeding programmes, advisory work and herd health management. Previous studies have raised questions about the quality of the disease data. The main aim of this study was to examine the country-specific completeness of the disease data, regarding clinical mastitis (CM) diagnosis, in each of the national cattle databases. A second aim was to estimate country-specific CM incidence rates (IRs). RESULTS: Over 4 months in 2008, farmers in the four Nordic countries recorded clinical diseases in their dairy cows. Their registrations were matched to registrations in the central cattle databases. The country-specific completeness of disease registrations was calculated as the proportion of farmer-recorded cases that could be found in the central database. The completeness (95% confidence interval) for veterinary-supervised cases of CM was 0.94 (0.92, 0.97), 0.56 (0.48, 0.64), 0.82 (0.75, 0.90) and 0.78 (0.70, 0.85) in Denmark, Finland, Norway and Sweden, respectively. The completeness of registration of all CM cases, which includes all cases noted by farmers, regardless of whether the cows were seen or treated by a veterinarian or not, was 0.90 (0.87, 0.93), 0.51 (0.43, 0.59), 0.75 (0.67, 0.83) and 0.67 (0.60, 0.75), respectively, in the same countries. The IRs, estimated by Poisson regression in cases per 100 cow-years, based on the farmers' recordings, were 46.9 (41.7, 52.7), 38.6 (34.2, 43.5), 31.3 (27.2, 35.9) and 26.2 (23.2, 26.9), respectively, which was between 20% (DK) and 100% (FI) higher than the IRs based on recordings in the central cattle databases. CONCLUSIONS: The completeness for veterinary-supervised cases of CM was considerably less than 100% in all four Nordic countries and differed between countries. Hence, the number of CM cases in dairy cows is underestimated. This has an impact on all areas where the disease data are used. 相似文献
80.
To understand the maintenance and resurgence of historical Human African Trypanosomiasis (HAT) foci, AFLP was used to genotype 100 Central African Trypanosoma brucei s.l. stocks. This technique confirmed the high genetic stability of T. b. gambiense group 1 stocks and the micro genetic variability within Central African T. b. gambiense stocks. It revealed several T. b. gambiense genotypes and allowed the identification of minor and major genotypes in HAT foci. The coexistence of these genotypes in the same focus suggests that clustering of stocks according to HAT focus does not provide the true genetic picture of trypanosome circulating within the disease focus because the minor genotypes are generally underestimated. The presence of minor and major genotypes in HAT foci may explain the persistence and the resurgence of Central African sleeping sickness foci. 相似文献