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   1191篇
  免费   169篇
  国内免费   22篇
林业   1篇
农学   9篇
  5篇
综合类   96篇
水产渔业   2篇
畜牧兽医   1268篇
园艺   1篇
  2024年   1篇
  2023年   15篇
  2022年   57篇
  2021年   35篇
  2020年   25篇
  2019年   30篇
  2018年   59篇
  2017年   92篇
  2016年   56篇
  2015年   75篇
  2014年   113篇
  2013年   79篇
  2012年   57篇
  2011年   88篇
  2010年   70篇
  2009年   87篇
  2008年   72篇
  2007年   71篇
  2006年   54篇
  2005年   41篇
  2004年   35篇
  2003年   23篇
  2002年   29篇
  2001年   16篇
  2000年   18篇
  1999年   25篇
  1998年   10篇
  1997年   9篇
  1996年   8篇
  1995年   8篇
  1994年   3篇
  1993年   8篇
  1992年   1篇
  1991年   2篇
  1990年   3篇
  1989年   1篇
  1987年   1篇
  1985年   1篇
  1982年   2篇
  1978年   1篇
  1977年   1篇
排序方式: 共有1382条查询结果,搜索用时 0 毫秒
111.
A 3-year-old crossbreed male dog was presented with a history of blunt facial trauma. Skull radiographs showed right zygomatic arch fracture. An electrocardiogram revealed bradycardia, first-degree atrioventricular block and QT prolongation. Standard biochemical profile including electrolytes was normal. Atropine response test (0.04 mg/kg intravenously) restored normal sinus rhythm at a rate of 140 bpm with normal QT and PR intervals. This observation is consistent with oculocardiac reflex secondary to zygomatic arch fracture.  相似文献   
112.
A 20‐month‐old female spayed Staffordshire Terrier (22.3 kg) presented to the Orthopedic Surgery Service at North Carolina State University Veterinary Teaching Hospital for evaluation of a 6‐week history of toe‐touching to nonweight‐bearing lameness in the right hind limb. Radiographs of the right stifle revealed a multiloculated lytic lesion of the distal femur, with a large open lytic zone centrally, numerous osseous septations peripherally, and focal areas of cortical thinning and loss. An aspirate of the right distal femoral lesion yielded mildly cloudy serosanguineous fluid. Cytologic examination of the fluid revealed a pleomorphic population of discrete cells that exhibited marked anisocytosis and anisokaryosis and a variable nuclear‐to‐cytoplasmic (N:C) ratio, which were interpreted as probable neoplastic cells, with few macrophages, and evidence of hemorrhage. Given the clinical signs of pain, lesion size, and concern for malignant neoplasia, amputation of the right hind limb was performed. Histologically, the lesion had undulating walls 1‐3 mm thick with a continuous outer layer of dense fibrous tissue and an inner layer composed of reactive cancellous bone with no cortical compacta remaining. Remnants of thin fibrous or fibro‐osseous septa projected from the bony wall into the cyst lumen. The final histologic diagnosis was a benign multiloculated solitary (unicameral) bone cyst of the distal right femur. Based on the histopathologic findings, it was speculated that the cells identified on cytology were a mixture of developing osteoclasts, osteoblasts, endothelial, and stromal cells. This is the first report describing the cytologic examination of a solitary bone cyst in veterinary medicine.  相似文献   
113.
114.
A 2‐year, 7‐month‐old female Chihuahua was admitted for a mammary mass measuring one cm in diameter. The dog had a history of demodicosis for 4 months and showed signs of pseudopregnancy at the time of the visit. Cytologic examination of an aspirate of the mass revealed a large number of macrophages containing nonstaining bacterial rods, which were acid‐fast in a Ziehl–Neelsen stain, suggesting mycobacterial infection. Histologic examination of the mass revealed a pyogranulomatous mastitis characterized by an infiltration with macrophages containing acid‐fast bacteria. Mycobacterium kansasii was subsequently cultured and identified by PCR. Surgical excision of the mass resulted in the growth of other dermal masses, but antimycobacterial treatment with rifampin and clarithromycin resolved these masses within 1 month. Three months after discontinuation of the treatment, similar organisms were found in aspirates of the enlarged bilateral inguinal lymph nodes by cytologic examination. Despite antimycobacterial treatment for another 4 months, there was no improvement and demodicosis also recurred. The dog eventually died of lymphoma 5 months after the relapse of mycobacterial infection. Although M kansasii is considered an important pathogen for pulmonary and cutaneous disease in people, there is only one report in a dog with an infection in a pleural effusion. As both adult‐onset demodicosis in dogs as well as mycobacterial infection in people have been associated with T‐lymphocyte deficiency, the M kansasii infection in this dog may have been associated with a condition of immune compromise.  相似文献   
115.
The discovery of the spiral bacterium Helicobacter pylori and its causative role in gastric disease in humans has brought a dramatic change to gastroenterology. Although spiral bacteria have been known for more than a century to infect the stomachs of dogs and cats, recent research has been conducted mainly in the wake of interest in H. pylori. H. pylori has not been found in dogs and only very rarely in cats and zoonotic risk is minimal. A variety of other Helicobacter spp. can infect the stomach of pets; however, their pathogenic role is far from clear, and they have a small but real zoonotic potential. The prevalence of gastric Helicobacter spp. in dogs and cats is high, irrespective of clinical signs, and as in human medicine, mode of transmission is unclear. The relationship of Helicobacter spp. to gastric inflammation in cats and dogs is unresolved, with inflammation, glandular degeneration, and lymphoid follicle hyperplasia accompanying infection in some but not all subjects. Circulating anti-Helicobacter immunoglobulin G antibodies have been detected in 80% of dogs with naturally acquired infection and most dogs and cats with experimental infection. The gastric secretory axis is similar in infected and uninfected cats and dogs and no relationship of infection to gastrointestinal ulcers has been found. Differences in the pathogenicity of Helicobacter spp. are apparent, because infection with H pylori is associated with a more severe gastritis than infection with other Helicobacter spp. in both cats and dogs. Rapid urease test, histopathology, and touch cytology are all highly accurate invasive diagnostic tests for gastric Helicobacter-like organisms in dogs and cats, whereas culture and polymerase chain reaction are the only means to identify them to the species level. Urea breath and blood tests or serology can be used to diagnose Helicobacter spp. noninvasively in dogs and cats. Most therapeutic studies in pets have not shown long-term eradication of Helicobacter spp. Whether this is due to reinfection or recrudescence has not been established.  相似文献   
116.
感染性犬2型腺病毒全基因组克隆及鉴定   总被引:12,自引:1,他引:12  
以犬 2型腺病毒 (canine adenovirus type- 2 ,CAV- 2 )自然弱毒株 YCA18基因组 DNA为模板 ,经 PCR扩增分别获得其双链两末端 10 13bp(U)和 972 bp(D)的 DNA序列 ,以首尾相接方式克隆入载体 p Poly2 ,获得重组质粒p Poly2 - UD。以 Hind 和 Bst B 双酶切 p Poly2 - UD,回收含载体和部分 U、D的大片段并与 CAV- 2 DNA共转化感受态 E.coli Sure TM,经菌体内同源重组 ,获得含有 CAV- 2全基因组序列的重组质粒 p Poly2 - CAV- 2。后者以 Cla 和 Asc 双酶切 ,释放 CAV- 2全基因组 ,通过脂质体介导转染 MDCK细胞 ,盲传 3代后重复转染 1次 ,4d后 ,出现腺病毒典型病变。细胞上清血凝效价为 1∶ 6 40 ,并可被 CAV- 2抗血清有效抑制。以上结果表明 ,本研究获得了具有感染性的CAV- 2全基因组重组质粒 ,为以 CAV- 2作为重组疫苗载体的系列研究奠定了重要基础。  相似文献   
117.
[目的]构建表达犬瘟热Onderstepoort株H蛋白的重组伪狂犬病毒,并研究其生物学特性。[方法]通过RT-PCR方法获得Onderstepoort株H基因,插入pcDNA3.1(+)建立好完整的真核细胞表达盒并将此表达盒亚克隆到转移载体p8AA上。在此基础上再将报告基因LacZ的表达盒插入转移载体,命名为p8AAZH。将p8AAZH与伪狂犬病毒(PRV)Bartha-K61株基因组共转染至BHK-21细胞中进行基因重组包装出毒,待细胞病变后收集病毒液。通过蓝色蚀斑筛选、PCR、电镜观察以及Westernblot,筛选纯化重组病毒并鉴定目的基因的表达。同时在BHK-21细胞上测定重组病毒的生长曲线。[结果]获得了表达H蛋白的重组伪狂犬病毒,重组病毒与亲本Bartha-K61株的生长曲线、病变特征相一致。[结论]成功构建了表达犬瘟热Onderstepoort株H蛋白的重组伪狂犬病毒,H基因的插入不影响重组病毒的增殖特性,为犬瘟热活病毒载体疫苗的研制与开发打下基础。  相似文献   
118.
犬瘟热病毒Lederle株H,N全基因序列分析及表达研究   总被引:1,自引:0,他引:1  
采用RT-PCR方法自犬瘟热病毒Lederle株基因组RNA中扩增出H基因(1 911 bp)和N基因(1 707 bp)片段,序列测定和分析表明与Onderstepoort株、CDV3株等疫苗毒株的同源性在95%以上,而与野外分离株的同源性介于90%~95%;以获得的H,N全基因片段为模板,分别扩增H基因近3′端996 bp的基因片段以及N基因中间高度保守区562 bp的基因片段,经克隆测序后分别插入原核表达载体pET-32a中进行表达,结果显示H片段和N片段分别表达大小约为57 kD和37 kD的融合蛋白,Western blotting检测结果显示,表达蛋白均可与CDV抗血清发生阳性反应,提示原核表达产物具有与CDV抗血清结合的免疫反应性。  相似文献   
119.
貂,貉,犬病毒性肠炎快速诊断试剂的研究   总被引:1,自引:0,他引:1  
用金黄葡萄球菌A蛋白(SPA)协同凝集方法(CoA)对貂、貉、犬病毒性肠炎快速诊断的试剂进行了制备,确定了制备。艺及该制剂的标准操作程序。本制剂特异性强,不与健康动物的组织及其他几种病毒病(犬瘟热、犬传染性肝炎、狂犬病等)发生交叉凝集反应,灵敏度高,通过该制剂CoA法与HA-HI法比较结果比现行的貂、貉、犬病毒性肠炎HA-HI诊断方法检出率高出30%,同时具有微量、操作简便、易掌握、快速等特点,可在3~5min获得诊断结果。  相似文献   
120.
Alterations in thyroid indices in critically ill dogs were studied retrospectively to determine the incidence of the euthyroid sick syndrome and to assess its prognostic relevance to survival. Sixty-seven dogs were classified as euthyroid bases on a TSH stimulation test. Forty-one of 67 (61%) of the euthyroid dogs had low baseline serum T4 concentrations (<1.5 ug/dl) and 38 of 67 (56%) of the euthyroid dogs had low baseline serum T3 concentrations (<75 ng/dl). There was no significant difference between either the baseline or the post-stimulation serum T4 concentrations when values of dogs that survived were compared with those that died. There was, however, a significant difference (P<0.05) between both the baseline and the post-stimulation values for T3 when survivors (100.3± 81 ng/dl, 143± 66 ng/dl) and non-survivors (64.2 ± 17.1 ng/dl, 96.6 ± 38.3 ng/dl) were compared. The euthyroid sick syndrome occurs commonly in critically ill dogs. Further, the extent of depression of serum concentrations of T3 may be correlated to mortality.  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