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   284篇
  免费   23篇
林业   18篇
农学   3篇
基础科学   1篇
  35篇
综合类   30篇
农作物   14篇
水产渔业   36篇
畜牧兽医   150篇
园艺   8篇
植物保护   12篇
  2024年   1篇
  2023年   3篇
  2022年   6篇
  2021年   9篇
  2020年   14篇
  2019年   13篇
  2018年   10篇
  2017年   15篇
  2016年   8篇
  2015年   8篇
  2014年   9篇
  2013年   17篇
  2012年   15篇
  2011年   22篇
  2010年   21篇
  2009年   16篇
  2008年   23篇
  2007年   14篇
  2006年   16篇
  2005年   14篇
  2004年   10篇
  2003年   10篇
  2002年   7篇
  2001年   4篇
  2000年   7篇
  1999年   1篇
  1998年   3篇
  1997年   2篇
  1996年   1篇
  1994年   2篇
  1991年   3篇
  1990年   1篇
  1985年   1篇
  1984年   1篇
排序方式: 共有307条查询结果,搜索用时 15 毫秒
61.
A wild Agassiz's desert tortoise, Gopherus agassizii, with bilateral eyelid reduction and plaques of tissue covering the superior surface of both corneas was examined in the field and subsequently submitted to the University of Florida for diagnostics. Polymerase chain reaction (PCR), from a swab of both corneas, was positive for Mycoplasma agassizii. Two months later, the tortoise was euthanatized and necropsied. There was increased bulbar exposure associated with dermal excoriation of periocular scales in both superior and inferior palpebra resulting in an increased palpebral fissure opening. Concurrently, there was bilateral conjunctivitis of the nictitating membranes and squamous metaplasia of the bulbar conjunctiva. Using PCR, Mycoplasma testudineum, another pathogen of tortoises, was identified in both nasal cavities, and the upper respiratory tract histopathological findings were consistent with those described for M. testudineum in Agassiz's desert tortoises. Although eye disease has been reported in desert and gopher (Gopherus polyphemus) tortoises with mycoplasmosis, widespread loss of palpebral tissue, conjunctivitis of the nictitans, and squamous metaplasia of the bulbar conjunctiva have not been reported in tortoises.  相似文献   
62.
63.
Trigeminal ganglion (TG) neurons are important target cells for many alphaherpesviruses and constitute a major site of virus latency and reactivation. Earlier we showed that porcine TG neurons are remarkably more resistant towards (apoptotic) cell death resulting from infection by the swine alphaherpesvirus pseudorabies virus (PRV) compared to a broad range of other primary porcine cell types and that this resistance does not depend on the strongly anti-apoptotic US3 viral protein kinase (Geenen, K., Favoreel, H.W., Nauwynck, H.J., 2005a. Higher resistance of porcine trigeminal ganglion neurons towards pseudorabies virus-induced cell death compared with other porcine cell types in vitro. J. Gen. Virol. 86, 1251-1260). Although other viral anti-apoptotic proteins may be involved in survival of TG neurons during PRV infection, an additional factor may be that TG neurons possess a cell type-dependent capacity to withstand apoptosis compared to other cell types. To investigate this, we treated uninfected porcine TG cultures, swine kidney cells, and porcine superior cervical ganglion (SCG) neurons with several apoptosis-inducing reagents (staurosporine, camptothecin and genistein). None of these reagents were able to trigger substantial apoptotic cell death in TG neurons, whereas non-neuronal TG cells, swine kidney cells, and SCG neurons showed a clear dose-dependent increase in apoptosis using either of these reagents. In conclusion, sensory TG neurons may contain a cell type-specific capacity to withstand different apoptotic assaults, including infection with an alphaherpesvirus.  相似文献   
64.
Obesity is a heritable trait and a risk factor for many common diseases such as type 2 diabetes, heart disease, and hypertension. We used a dense whole-genome scan of DNA samples from the Framingham Heart Study participants to identify a common genetic variant near the INSIG2 gene associated with obesity. We have replicated the finding in four separate samples composed of individuals of Western European ancestry, African Americans, and children. The obesity-predisposing genotype is present in 10% of individuals. Our study suggests that common genetic polymorphisms are important determinants of obesity.  相似文献   
65.
66.
A 7-month-old female spayed domestic shorthair cat was presented for investigation of stertor, open mouth breathing without apparent distress, and chronic bilateral nasal discharge that was unresponsive to antibiotics. Complete bilateral bony choanal atresia was diagnosed with computed tomography and nasopharyngoscopy. Choanal atresia is an uncommon congenital condition where the choana (nasal passage into the nasopharynx) is blocked by abnormal bone or soft tissue uni- or bilaterally. The cat's clinical signs improved dramatically immediately after trans-palatal surgical correction. Post-surgical complications included the development of nasopharyngeal scar tissue and subsequent stenosis, persistent right-sided nasal discharge, and permanent damage to the right eye (blindness and cataract formation). Nasopharyngeal stenosis was managed with repeated balloon dilatations and temporary stenting, and the owner reported an excellent quality of life at 8-month follow-up. Bilateral bony choanal atresia has not been previously reported in cats. Uni- or bilateral choanal atresia should be considered in young cats presenting with refractory stertor, chronic nasal discharge, and/or open mouth breathing.  相似文献   
67.
ObjectiveTo describe the pharmacodynamics and pharmacokinetics following an intravenous (IV) bolus dose of medetomidine in the horse.Study designProspective experimental trial.AnimalsEight, mature healthy horses age 11.7 ± 4.6 (mean ± SD) years, weighing 557 ± 54 kg.MethodsMedetomidine (10 μg kg?1) was administered IV. Blood was sampled at fixed time points from before drug administration to 48 hours post administration. Behavioral, physiological and biochemical data were obtained at predetermined time points from 0 minutes to 24 hours post administration. An algometer was also used to measure threshold responses to noxious stimuli. Medetomidine concentrations were determined by liquid chromatography-Mass Spectrometry and used for calculation of pharmacokinetic parameters using noncompartmental and compartmental analysis.ResultsPharmacokinetic analysis estimated that medetomidine peaked (8.86 ± 3.87 ng mL?1) at 6.4 ± 2.7 minutes following administration and was last detected at 165 ± 77 minutes post administration. Medetomidine had a clearance of 39.6 ± 14.6 mL kg?1 minute?1 and a volume of distribution of 1854 ± 565 mL kg?1. The elimination half-life was 29.1 ± 12.5 minutes. Glucose concentration reached a maximum of 176 ± 46 mg dL?1 approximately 1 hour post administration. Decreased heart rate, respiratory rate, borborygmi, packed cell volume, and total protein concentration were observed following administration. Horses lowered their heads from 107 ± 12 to 20 ± 10 cm within 10 minutes of drug administration and gradually returned to normal. Horse mobility decreased after drug administration. An increased mechanical threshold was present from 10 to 45 minutes and horses were less responsive to sound.Conclusion and clinical relevance Behavioral and physiological effects following intravenous administration positively correlate with pharmacokinetic profiles from plasma medetomidine concentrations. Glucose concentration gradually transiently increased following medetomidine administration. The analgesic effect of the drug appeared to have a very short duration.  相似文献   
68.
69.
Although bacteria use different iron compounds in vitGro, the possibility that microbes distinguish between these iron sources during infection has hitherto not been examined. We applied stable isotope labeling to detect source-specific iron by mass spectrometry and show that Staphylococcus aureus preferentially imports heme iron over transferrin iron. By combining this approach with computational genome analysis, we identified hts (heme transport system), a gene cluster that promotes preferred heme iron import by S. aureus. Heme iron scavenging by means of hts is required for staphylococcal pathogenesis in animal hosts, indicating that heme iron is the preferred iron source during the initiation of infection.  相似文献   
70.
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