首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   138篇
  免费   10篇
林业   8篇
农学   3篇
  5篇
综合类   18篇
农作物   3篇
水产渔业   13篇
畜牧兽医   97篇
植物保护   1篇
  2023年   1篇
  2021年   1篇
  2020年   5篇
  2019年   5篇
  2018年   1篇
  2017年   4篇
  2016年   4篇
  2015年   6篇
  2014年   5篇
  2013年   4篇
  2012年   5篇
  2011年   8篇
  2010年   5篇
  2009年   4篇
  2008年   5篇
  2007年   6篇
  2006年   5篇
  2005年   5篇
  2004年   3篇
  2003年   5篇
  2002年   3篇
  2001年   7篇
  1999年   5篇
  1998年   6篇
  1997年   4篇
  1996年   11篇
  1995年   1篇
  1994年   3篇
  1993年   4篇
  1992年   4篇
  1991年   5篇
  1990年   7篇
  1988年   1篇
排序方式: 共有148条查询结果,搜索用时 453 毫秒
71.
72.
Objective To investigate the distribution and prevalence of mucormycosis in platypus (Ornithorhynchus anatinus) from the Inglis, Emu and Black-Detention catchment areas in north-west Tasmania. Procedure A field study was performed and resulted in the examination of 44 wild platypuses; in addition, one dead platypus and two live platypuses were examined after they were independently submitted to a local veterinary clinic. Results No cases of mucormycosis were conclusively diagnosed. One platypus with signs consistent with those previously described in cases of mucormycosis was captured in the Emu River catchment. However, laboratory tests did not provide a definitive diagnosis for the lesion. Two platypuses from the Inglis catchment area had signs very similar to those previously described in cases of mucormycosis, but laboratory tests found Corynebacterium ulcerans to be the likely cause of the cutaneous ulcers on one of these platypuses and an unidentified fungal agent to be the cause of a cutaneous nodule in the other. Conclusions These findings do not prove that mucormycosis is absent from the populations studied. However, they may indicate that the prevalence of disease is low. The possibility that Mucor amphibiorum is present in a subclinical form in platypuses, or infecting another reservoir, is not excluded. The findings also suggest that caution should be exercised when diagnosing mucormycosis based on clinical findings alone and raise the possibility that some cases may have been incorrectly diagnosed.  相似文献   
73.
The mudskipper Scartelaos gigas is expected to experience repeated severe hypoxia in its environment. Hence, we conducted experiments on the oxygen consumption rate (OCR) and OCR rhythm of S.?gigas at low graded dissolved oxygen (DO) levels, without access to atmospheric air, to estimate its tolerance to hypoxia. A dominant circadian OCR rhythm was observed at the control DO level of 6.96?C7.78?mg?O2/l. This rhythm was unchanged until 2.06?mg?O2/l, even though the amplitude of the peak was somewhat diminished at 2.06?C2.87?mg?O2/l. The OCR rhythm amplitude was greatly diminished and the rhythm period was also greatly changed at 1.23?C2.05?mg?O2/l. Nevertheless, the mean OCR (0.11?ml?O2/g WW/h) at 1.23?C2.05?mg O2/l was similar to that of control (0.12?ml O2/g?WW/h). Thus, the weakness and period change of the OCR rhythm kept the metabolic rate level similar to control. These results suggest that S.?gigas does not have normal metabolic activity at 1.23?C2.05?mg O2/l but barely manages to endure this DO level as a pre-emergency state. This species could be inhibited under a longer maintenance period at DO level of 1.23?C2.05?mg?O2/l or still lower. It can be concluded that S.?gigas is quite tolerant to low DO environment and may have a specific strategy for such tolerance.  相似文献   
74.
75.
Sacbrood virus (SBV) is one of the most destructive honey bee viruses. The virus causes failure to pupate and death in both larvae and adult bees. Genetic analysis of SBV infected honey bees (Apis cerana) from five different provinces was carried out based on three nucleotide sequences; one partial structural protein coding sequence and two non-structural protein coding sequences. Sequences amplified by three specific primer pairs were aligned and compared with reference sequences deposited in the GenBank database. Sequence alignments revealed a low level of sequence variation among Korean isolates (≥ 98.6% nucleotide identity), regardless of the genome regions studied or the geographic origins of the strains. Multiple sequence comparisons indicated that Korean SBV isolates are genetically closely related to Chinese and other Asian strains. Interestingly, the Korean SBV isolates showed a number of unique nucleotides and amino acids that had not been observed in other published strains. Korean and other Asian isolates from the host A. cerana and the UK, European and Japanese strains from the host Apis mellifera showed differences in nucleotide and deduced amino acid identities. This suggests that host-specificity exists among SBV strains isolated from different species. Phylogenetic relatedness between compared sequences was analyzed by MEGA 4.1 software using the neighbor-joining (NJ) method with a boot-strap value of 1000 replicates. Obtained topologies were in agreement with previous studies, in which a distinct group of SBV was formed by UK and European genotypes and another group was comprised of Asian genotypes including strains that originated from China, Japan (japonica), India and Nepal. However, phylogeny based on a partial protein structural coding sequence grouped all Korean SBV isolates identified in A. cerana as a separate cluster. Our findings suggest that further study, including Korean SBV isolated from A. mellifera, is needed.  相似文献   
76.
The effects of two phytosterol derivatives of beta-sitosterol, a lipophilic derivative (LPSS) and a hydrophilic derivative (HPSS), on cholesterol uptake and blood lipoprotein levels in rats were compared with those of beta-sitosterol. LPSS and HPSS have solubilities of up to 0.05 g/mL in edible oil and 0.15 g/mL in water at 25 degrees C, respectively. The intragastric administration of either 30 or 50 mg of phytosterols with 10 mg of [4- (14)C]-cholesterol per kg of body weight once a day for 3 consecutive days reduced cholesterol uptake by approximately 30% compared to controls that received cholesterol alone. Feeding a cholesterol-enriched diet containing 1% or 3% beta-sitosterol, LPSS, or HPSS for 2 and 4 weeks resulted in lowered levels of total blood cholesterol and reduced the atherogenic index in all groups. These results indicate that LPSS and HPSS have comparable effects to beta-sitosterol in lowering blood cholesterol levels but they differ from beta-sitosterol in having a solubility advantage.  相似文献   
77.
Ionophorous antibiotics have been popularly used in the treatment of avian coccidiosis. Tissue residue of these antibiotics may be found in poultry, we have sought safe alternative anticoccidial herbal materials for the control of avian coccidiosis. Efficacy of extracts from 15 different herbs, including Bupleurum chinese DC, Sophora flavescens Aiton, and Artemisia annua Linne was tested against Eimeria tenella. One-day-old broiler chicks were infected with a USDA reference book of E. tenella, and administered various herbal extracts.Survival rates, lesion scores, body weight gains, bloody diarrhea, and oocysts excretions were investigated at the first and the second week after infection. Bloody diarrhea in the S. flavescens and Sinomenium acutum treated groups was milder than that of the other infected groups. Survival rates in the groups treated with Ulmus macrocarpa (100%), Pulsatilla koreana, Torilis japonica, Artemisia asiatica and S. flavescens (90%) were higher than that of the infected control group (70%). Lesion scores in the groups treated with U. macrocarpa (1.40+/-1.14) or Pulsatilla koreana (1.60+/-1.82) were significantly lower than those of the infected control group (3.00+/-1.10). During the first week after infection, the weight gains in the groups treated with Quisqualis indica (232.9+/-43.5 g), S. flavescens (214.4+/-46.1 g) and S. acutum (211.3+/-29.4 g) were significantly higher than the infected control group (172.4+/-17.6 g).In conclusion, the data of the survival rates, bloody diarrhea symptoms, lesion scores, body weight gains and oocyst excretions indicate that the extract of S. flavescens was the most effective. P. koreana, S. acutum, U. macrocarpa and Q. indica were also effective. Further research on the above herbal materials will be carried out by the authors by chemical analysis of the extracts.  相似文献   
78.
Ketamine is a rapid acting, potent, nonspecific, noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist commonly used for inducing general anesthesia and for providing post-operative pain management and may possibly lessen the need for other potentially harmful or contraindicated analgesics in camelids, such as nonsteroidal anti-inflammatory drugs. Prior to determining the effectiveness of CRI ketamine for analgesia, a safe, sub-anesthetic dose was established that did not produce untoward side effects, sedation or alter normal behavior. Six healthy male alpacas (40–90 kg) were used for the trial and each acted as its own control. Each alpaca was randomly assigned to receive ketamine at 20 and 40 μg kg–1 minute–1 in 500 mL saline. A blinded observer recorded heart rate, respiratory rate, and body temperature hourly, and behavior for 8 hours. There was a 72-hour washout period between each dosing regime. An equal volume saline CRI without ketamine was used as a control. Each alpaca was allowed a one-week washout prior to being anesthetized with isoflurane using mask induction. After achieving a stable plane of anesthesia, the MAC value for isoflurane was determined. Ketamine was infused at 40 μg kg–1pre-existing pain is unknown, but for elective procedures, preemptive analgesia using ketamine CRI in alpacas may be beneficial.  相似文献   
79.
Biocompatible silica-overcoated magnetic nanoparticles containing an organic fluorescence dye, rhodamine B isothiocyanate (RITC), within a silica shell [50 nm size, MNP@SiO2(RITC)s] were synthesized. For future application of the MNP@SiO2(RITC)s into diverse areas of research such as drug or gene delivery, bioimaging, and biosensors, detailed information of the cellular uptake process of the nanoparticles is essential. Thus, this study was performed to elucidate the precise mechanism by which the lung cancer cells uptake the magnetic nanoparticles. Lung cells were chosen for this study because inhalation is the most likely route of exposure and lung cancer cells were also found to uptake magnetic nanoparticles rapidly in preliminary experiments. The lung cells were pretreated with different metabolic inhibitors. Our results revealed that low temperature disturbed the uptake of magnetic nanoparticles into the cells. Metabolic inhibitors also prevented the delivery of the materials into cells. Use of TEM clearly demonstrated that uptake of the nanoparticles was mediated through endosomes. Taken together, our results demonstrate that magnetic nanoparticles can be internalized into the cells through an energy-dependent endosomal-lysosomal mechanism.  相似文献   
80.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号