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排序方式: 共有102条查询结果,搜索用时 15 毫秒
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Concerted evolution is the production and maintenance of homogeneity within repeated families of DNA. Two mechanisms--unequal crossing over and biased gene conversion--have been the principal explanations of concerted evolution. Concerted evolution of ribosomal DNA (rDNA) arrays is thought to be largely the result of unequal crossing over. However, concerted evolution of rDNA in parthenogenetic lizards of hybrid origin is strongly biased toward one of two parental sequences, which is consistent with biased gene conversion as the operative mechanism. The apparent gene conversions are independent of initial genome dosage and result in homogenization of rDNA arrays across all nucleolar organizer regions. 相似文献
3.
Bethany I. Baker-Cook Antonietta L. Moritz Danielle Zwueste Karen Schwean-Lardner Karen L. Machin 《The Canadian veterinary journal. La revue veterinaire canadienne》2021,62(4):367
The use of T-61 as a sole euthanasia agent for birds was investigated. Nine broiler chickens (Gallus gallus domesticus) were euthanized by intravenous T-61 and assessed for insensibility [brainstem reflexes: nictitating membrane reflex (NIC), palpebral blink reflex (PAL)], brain death [isoelectric electroencephalogram activity (EEG)], cessation of audible heartbeat, and abnormal electrocardiogram. Birds were considered dead when the heart rate was less than 180 beats/minute with an isoelectric EEG. No vocalization or wing flapping occurred. Both NIC and PAL were lost 10.5 s from start of injection and audible heartbeat ceased at 24.5 s. Latency to isoelectric activity was 16.6 s. All but 1 bird died within 60 s. Rapid induction of insensibility meant birds did not experience pain and distress within 10.5 s from start of injection and birds were not conscious during cardiac and circulatory arrest. Intravenous injection of T-61 is an effective and efficient euthanasia method for birds. 相似文献
4.
Moritz C 《Science (New York, N.Y.)》1983,220(4598):735-737
Chromosome variation in the gekkonid lizard Heteronotia binoei reveals that this endemic Australian vertebrate reproduces by parthenogenesis. Triploid parthenogenetic females are distributed throughout central and western Australia and are all heterozygotes for one or more pericentric inversions that also distinguish the extant bisexual diploid cytotypes. These data on karyotype provide strong evidence that the various clones have arisen through multiple hybridization events between bisexual ancestors. 相似文献
5.
Hans Wullaert Moritz Bigalke Jürgen Homeier Nixon Cumbicus Carlos Valarezo Wolfgang Wilcke 《植物养料与土壤学杂志》2013,176(6):892-903
The tropical montane forests of the E Andean cordillera in Ecuador receive episodic Sahara‐dust inputs particularly increasing Ca deposition. We added CaCl2 to isolate the effect of Ca deposition by Sahara dust to tropical montane forest from the simultaneously occurring pH effect. We examined components of the Ca cycle at four control plots and four plots with added Ca (2 × 5 kg ha–1 Ca annually as CaCl2) in a random arrangement. Between August 2007 and December 2009 (four applications of Ca), we determined Ca concentrations and fluxes in litter leachate, mineral soil solution (0.15 and 0.30 m depths), throughfall, and fine litterfall and Al concentrations and speciation in soil solutions. After 1 y of Ca addition, we assessed fine‐root biomass, leaf area, and tree growth. Only < 3% of the applied Ca leached below the acid organic layer (pH 3.5–4.8). The added CaCl2 did not change electrical conductivity in the root zone after 2 y. In the second year of fertilization, Ca retention in the canopy of the Ca treatment tended to decrease relative to the control. After 2 y, 21% of the applied Ca was recycled to soil with throughfall and litterfall. One year after the first Ca addition, fine‐root biomass had decreased significantly. Decreasing fine‐root biomass might be attributed to a direct or an indirect beneficial effect of Ca on the soil decomposer community. Because of almost complete association of Al with dissolved organic matter and high free Ca2+ : Al3+ activity ratios in solution of all plots, Al toxicity was unlikely. We conclude that the added Ca was retained in the system and had beneficial effects on some plants. 相似文献
6.
Estelle H Venter Moritz van Vuuren Johann Carstens Martha L van der Walt Badenhorst Nieuwoudt Helena Steyn Nick P J Kriek 《Journal of zoo and wildlife medicine》2003,34(1):76-81
Low cheetah (Acinonyx jubatus) birth rates were observed for a long time in a captive breeding facility in which Salmonella, which was possibly present in contaminated beef, was isolated from still-born lion (Panthera leo) cubs. Salmonella, including 14 isolates of Salmonella serovar typhimurium and 19 isolates of Salmonella serovar muenchen, was subsequently isolated 47 times from 378 meat samples at the facility during a 13-mo period. Salmonella, including 26 isolates of S. serovar typhimurium, 10 of S. serovar muenchen, and 11 other serovars, also was isolated 54 times from 119 fecal samples. Only three plasmid profiles were identified in 59 S. typhimurium isolates from both meat and fecal samples. Although random-amplified polymorphic DNA fingerprinting using different primers in the polymerase chain reaction was able to distinguish between S. typhimurium and S. muenchen and to demonstrate similar chromosomal DNA fingerprints in some of the isolates from meat and feces, the results were not consistent enough to prove that the Salmonella in the feces originated from contaminated meat. However, the predominance of only two serovars in the meat fed to carnivores and in the feces of these animals suggests that the meat was the source of the Salmonella organisms in the feces. 相似文献
7.
Nephrogenic diabetes insipidus is characterized by polyuria, hyposthenuria and compensatory polydipsia. With conventional clinical and laboratory examinations the diagnosis can be established and the differential diagnostic diseases excluded. In order to verify the diagnosis, differentiate the condition from central and nephrogenic diabetes insipidus and rule out psychogenic polydipsia, additional laboratory studies are required: of these, the concentration test, modified Carter-Robbins test and AVP stimulation test are described. 相似文献
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Inflammatory cytokine and C‐reactive protein concentrations in dogs with systemic inflammatory response syndrome 下载免费PDF全文
10.
The present study investigated 3 methods of hemoglobin (Hb) determination in goats using the ADVIA 120 and ADVIA 2120 systems. Ethylenediaminetetraacetic acid anticoagulated caprine blood samples (n = 40 goats) were subjected to Hb determination via the cyanmethemoglobin methods in both instruments and a novel, cyanide-free, colorimetric method with the ADVIA 2120. Statistical analysis of the data included a linear regression, Passing-Bablok regression, and Bland-Altman diagram. Colorimetric Hb results determined with both analyzers had excellent correlation (r = 0.98); however, a mean proportional bias of -19.1% was present in comparison to the reference method. There also was excellent agreement between cellular Hb concentrations when measured with both analyzers (r = 0.96), and the constant bias was close to zero. However, imprecision was higher compared to colorimetric methods. Excellent to fair agreement was evident for all calculated erythrocyte and Hb variables. Because of the excellent correlation between the ADVIA 120 and ADVIA 2120, the cyanide-free method of Hb determination could be used with caprine blood specimens; however, the proportional bias must be considered. 相似文献