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   105篇
  免费   1篇
林业   4篇
农学   4篇
  13篇
综合类   5篇
农作物   1篇
水产渔业   2篇
畜牧兽医   63篇
植物保护   14篇
  2022年   1篇
  2021年   3篇
  2020年   2篇
  2016年   6篇
  2015年   2篇
  2014年   5篇
  2013年   7篇
  2012年   7篇
  2011年   6篇
  2010年   4篇
  2009年   1篇
  2008年   10篇
  2007年   9篇
  2006年   6篇
  2005年   9篇
  2004年   8篇
  2003年   12篇
  2002年   1篇
  2001年   4篇
  2000年   1篇
  1997年   1篇
  1985年   1篇
排序方式: 共有106条查询结果,搜索用时 31 毫秒
1.
Androgen induces production of male effect pheromone in female goats   总被引:1,自引:0,他引:1  
Previously we showed that the primer pheromone responsible for the "male effect" was produced in specific skin regions of castrated male goats by androgen treatments. In the present study, we examined whether androgen can also induce production of the male effect pheromone in female goats. Capsules containing dihydrotestosterone (DHT) or testosterone (T) were subcutaneously implanted into six ovariectomized (OVX) goats for 28 days. Small skin samples were collected from the head and rump regions, and the pheromone activity of their ether extracts was examined using a bioassay that monitors the electrophysiological manifestation of the hypothalamic gonadotropin-releasing hormone pulse generator as multiple-unit activity. Behaviors of OVX goats towards ovary-intact estrous goats were also examined before and at the end of DHT or T treatment. Before androgen treatment, neither the head nor rump skin samples in OVX goats showed pheromone activity. DHT treatment induced pheromone activity in the head skin sample of six OVX goats and in the rump skin sample of two OVX goats. Similar results were obtained by T treatment. In addition, OVX goats treated with T showed masculine-type sexual behaviors such as courtship and mounting behaviors towards the estrous goats. These results demonstrate that androgen is capable of inducing primer pheromone activity in the female and suggest that the synthesis pathway of the male effect pheromone exists in both sexes in the goat.  相似文献   
2.
Diesel exhaust particles (DEPs) contain polycyclic aromatic hydrocarbons (PAH) that bind to aryl hydrocarbon receptors (AhRs) and decrease sperm production. Since it is not clear if AhR mediates DEP toxicity, we investigated the effect of DEPs in four strains of mice that have different AhR responsiveness. We treated BALB/c, C57BL/6, ICR and DBA/2 mice with DEP suspensions and compared their toxicity in each strain. In both the vehicle- and DEP-treated groups, ethoxyresorufin-O-deethylase (EROD) activity, as an indirect index of AhR activity, was increased in the order of BALB/c > C57BL/6 > ICR > DBA/2. Only BALB/c and C57BL/6 mice had significantly lower daily sperm production (DSP) than vehicle-treated mice. All strains exhibited increased sperm abnormalities. In particular, the C57BL/6, ICR and DBA/2 mice exhibited significantly increased abnormalities. A significant correlation was found between EROD activity and DSP or incidence of morphologically abnormal sperm. These data suggest that DEP toxicity may affect the male reproductive system in an AhR-dependent manner.  相似文献   
3.
Basidiocarps of the violet root rot fungus, Helicobasidium mompa, are less frequently used for isolation than are mycelial strands and sclerotia even though the basidiocarps are conspicuously produced at the trunk base of diseased plants. Basidiocarps are also more suitable for storage. This paper describes an improved method for obtaining pure cultures from basidiocarps using microcentrifuge tubes to facilitate the awkward steps of rinsing fungal materials under a dissecting microscope. Received 28 June 2000/ Accepted in revised form 4 August 2000  相似文献   
4.
Stress-induced hyperthermia is observed in animals exposed to stressful conditions. In our previous study, plant-derived fragrances such as green odor and alpha-pinene were shown to suppress this stress response in rats. In the present study, we examined the concentration-dependence of the alpha-pinene effects on stress-induced hyperthermia. Male rats carrying telemetry transmitters were transferred individually to a new cage containing bedding that had been sprayed with 0.3, 0.03, and 0.003% concentrations of alpha-pinene or control solvent. Following transfer to the novel environment, the body temperature increased significantly, and this response was clearly suppressed when the cage was scattered with 0.03% alpha-pinene only. These results suggest that the effect of alpha-pinene on stress-induced hyperthermia can be observed only at a certain concentration.  相似文献   
5.
A major constituent of the characteristic "goaty odor" 4-ethyl octanoic acid (4EOA) was previously shown to have no primer pheromone activity. This was also confirmed by our own bioassay system utilizing the recording technique of neural activity of the hypothalamic gonadotropin-releasing hormone pulse generator in goats. However, when the synthetic 4EOA solution was kept at room temperature for several months, primer pheromone activity appeared in the same solution. Headspace gas chromatography/mass spectrometry analysis revealed that there were several newly formed substances in addition to 4EOA samples with primer pheromone activity. These results suggest that 4EOA derived substance(s) but not 4EOA itself is(are) primer pheromone in goats.  相似文献   
6.
An epidemiological survey for Theileria annulata infection was conducted in 12 selected villages around Ankara in Central Anatolia, Turkey, during the period April 1990 to January 1993. During the survey, 198 cattle of 30 local breeds, 84 Holstein-Friesian×local breeds and 84 Holstein-Friesian breed were examined for antibodies to T. annulata and the presence of the vector ticks. Four species of Hyalomma ticks were identified: Hyalomma anatolicum anatolicum, Hyalomma anatolicum excavtum, Hyalomma detritum and Hyalomma marginatum marginatum. Salivary gland staining indicated that infected adult ticks of all four species were present and, therefore, were implicated in the transmission of tropical theileriosis in the field. Generally, the Hyalomma infestation rate was low, with the heaviest infestations occurring on the older animals. Young adults and calves had very low infestation rates. Most ticks seen on cattle were adults, very few nymphs were found. The blood smear and serological examination of the 198 cattle conducted in March, before the start of the first disease season, showed that the prevalence of piroplasmosis was 11.1% (22 out of 198) and the seroprevalence of T. annulata was 10.6% (21 out of 198). Forty-three animals were then excluded from the study because they were seropositive and/or harboured piroplasms. Ninety-two seronegative animals showed piroplasmosis (92 out of 155) and 34 seronegative animals became seropositive for T. annulata (34 out of 155) during the three disease seasons. One animal became clinically ill with tropical theileriosis and required treatment. The incidence of cattle showing piroplasmosis and disease in the total study sample was 50.7% and 0.5% per disease season, respectively. The seroconversion rate of new infection with T. annulata in the total study was 14.3% per animal season. The number of cattle showing piroplasmosis was much greater than the number of seropositive cattle, which may indicate the presence of another species of Theileria. The two different management systems encountered in the study were considered to have influenced the tick infestation levels.  相似文献   
7.
Plants respond to attack by pathogens through various defense mechanisms. These defense responses are triggered by a variety of molecules derived from pathogenic microorganisms as well as host plants. In this study, we developed a high-throughput screening method using a cell-based lawn format assay for the identification of novel peptides that can induce plant defense responses from combinatorial peptide libraries. Solid-phase peptide libraries were synthesized using a photocleavable linker and immobilized using agarose gel. The peptides were partially cleaved from beads, and the agarose gel was layered on the tobacco cells. The defense response was then observed by detecting the generated H2O2 using a sensitive H2O2 indicator dye, N-(carboxymethylaminocarbonyl)-4,4'-bis(dimethylamino)diphenylamine sodium salt (DA-64). Using this assay format, a 6859-member peptide library based on the sequence of flagellin-derived peptides was screened, and several structural features important for the activity were obtained.  相似文献   
8.
We report the draft genome sequence of the model moss Physcomitrella patens and compare its features with those of flowering plants, from which it is separated by more than 400 million years, and unicellular aquatic algae. This comparison reveals genomic changes concomitant with the evolutionary movement to land, including a general increase in gene family complexity; loss of genes associated with aquatic environments (e.g., flagellar arms); acquisition of genes for tolerating terrestrial stresses (e.g., variation in temperature and water availability); and the development of the auxin and abscisic acid signaling pathways for coordinating multicellular growth and dehydration response. The Physcomitrella genome provides a resource for phylogenetic inferences about gene function and for experimental analysis of plant processes through this plant's unique facility for reverse genetics.  相似文献   
9.
Seven kinds of hydroxycinnamic acid derivatives identified as 3-caffeoylquinic acid (3-CQA), 4-caffeolyquinic acid (4-CQA), 5-caffeoylquinic acid (5-CQA), 5-feruloylquinic acid (5-FQA), 3,4-dicaffeoylquinic acid (3,4-diCQA), 3,5-dicaffeoylquinic acid (3,5-diCQA), and 4,5-dicaffoylquinic acid (4,5-diCQA) by MS, 1H NMR, and HPLC analyses were isolated from low-quality (immature) and commercial quality green coffee beans. The quantity of chlorogenic acid isomers (10.4 g/100 g), especially 5-CQA, in commercial green coffee beans [West Indische Bereiding (West India processing beans from Sumatra Island, Indonesia, WIB)] was higher than that in low-quality beans [9.1 g/100 g, Eerste Kwaliteit (Export low-quality beans from Java Island, Indonesia, EK-1, grade 4)], whereas little difference in diCQAs was detected between the two kinds of beans. The free radical scavenging activity of these isolates was evaluated in assay systems using DPPH free radicals and superoxide anion radicals generated by xanthine-XOD. The diCQAs showed strong (1.0-1.8-fold) free radical scavenging activity compared to commonly used antioxidants such as alpha-tocopherol and ascorbic acid. The potency order of superoxide anion radical scavenging activity was diCQAs > caffeic acid, CQAs > 5-FQA. The activities of the diCQAs were twice as effective as those of CQAs and 4 times as effective as that of 5-FQA. The diCQAs also exhibited more potent (2.0-2.2-fold) tyrosinase inhibitory activities compared to CQAs, arbutin, and ascorbic acid. The isolates exhibited antiproliferation activities in four cancer cell lines, U937, KB, MCF7, and WI38-VA. Among these, KB cells were most sensitive (IC50 = 0.10-0.56 mM).  相似文献   
10.
In this study, clinical, parasitological, macroscopical, histopathological and immunohistochemical examinations were performed on 19 kids and 11 lambs (30 animals) with neonatal diarrhoea to detect the presence of Coronavirus, Cryptosporidium parvum and Giardia intestinalis. Clinically, severe dehydration, yellowish-green to brown coloured diarrhoea and death were observed. Mortality rates were 10-30% in the examined flocks. The most common agent was C. parvum diagnosed in 20 animals as a single causative agent, whereas G. intestinalis was found in 5 of 30 animals. These two protozoa were detected together in 4 animals upon faeces examination. Fifteen of 24 cases of C. parvum and 3 of 11 cases of G. intestinalis were also confirmed histopathologically. Following immunohistochemical examination, all cryptosporidiosis cases were confirmed by positive immunostaining of intestinal sections. Two additional Giardiosis cases with negative results upon parasitological and histopathological examinations were diagnosed by means of immunohistochemical examination. Coronavirus was detected immunohistochemically in one kid with neonatal enteritis. Following diagnosis, herds were treated with Trimethoprim + Sulfodoxine and multivitamin complexes. Intravenous and intramuscular administrations of these drugs were effective for both treatment and prevention of neonatal diarrhoea in lambs and kids.  相似文献   
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