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   172篇
  免费   6篇
林业   8篇
农学   2篇
基础科学   2篇
  16篇
综合类   21篇
农作物   12篇
水产渔业   1篇
畜牧兽医   111篇
园艺   3篇
植物保护   2篇
  2021年   1篇
  2020年   2篇
  2019年   3篇
  2018年   1篇
  2017年   1篇
  2016年   2篇
  2015年   2篇
  2014年   7篇
  2013年   2篇
  2012年   7篇
  2011年   7篇
  2010年   3篇
  2009年   6篇
  2008年   8篇
  2007年   12篇
  2006年   10篇
  2005年   5篇
  2004年   7篇
  2003年   4篇
  2002年   8篇
  2001年   4篇
  2000年   7篇
  1999年   8篇
  1998年   2篇
  1997年   1篇
  1995年   1篇
  1993年   4篇
  1992年   2篇
  1991年   5篇
  1990年   3篇
  1989年   4篇
  1988年   4篇
  1987年   1篇
  1986年   5篇
  1985年   3篇
  1984年   3篇
  1983年   3篇
  1979年   1篇
  1974年   1篇
  1973年   1篇
  1970年   1篇
  1969年   1篇
  1967年   1篇
  1964年   1篇
  1960年   1篇
  1940年   1篇
  1929年   1篇
  1926年   3篇
  1925年   4篇
  1924年   2篇
排序方式: 共有178条查询结果,搜索用时 187 毫秒
51.
A 17-year-old Quarter horse mare was referred to Cornell University for postmortem examination after 72 hours of encephalopathy that consisted of depression, mania, and blindness. A plasma sample and cerebral spinal fluid demonstrated hyperammonemia. Gross necropsy examination findings included the following: mild icterus, a transmural mass in the glandular portion of the gastric fundus, multiple masses throughout the liver, and a large tumor thrombus in the portal vein. Microscopically, the gastric mass, hepatic masses, and portal vein thrombus were composed of similar neoplastic epithelial cells that formed variably sized acini and branching cords separated by a dense desmoplastic stroma. Throughout the cerebral frontal cortex were numerous Alzheimer type II astrocytes. Hepatic encephalopathy was caused by gastric adenocarcinoma, with metastasis to the liver and the portal vein. The clinical and pathologic lesions from this unique case, as well as hyperammonemia and portal vein thrombosis in the pathogenesis of hepatic encephalopathy, are discussed.  相似文献   
52.

•Context   

Distribution of removed trees among species and diameter classes is usually used to characterize selection harvesting. This information is, however, rarely available when analysing past time series. The challenge is then to determine the minimal level of information required to characterize harvests.  相似文献   
53.
Necropsy examination was performed on an 8.5-year-old Finnish ewe euthanatized because of progressive respiratory distress, cachexia, and weakness. Significant postmortem findings included a diffusely enlarged, dark-red friable liver, mild splenomegaly, and mild mesenteric lymphadenopathy. Examination of multiple tissue sections revealed intravascular atypical mononuclear cells in all tissues examined, with a leukemic pattern of infiltration of mesenteric lymph nodes, liver, lung, and spleen. Neoplastic cells were positive for CD79a and negative for CD-3, BLA.36, and CD68 leukocytic markers. The final diagnosis was B-cell leukemia.  相似文献   
54.
55.
56.
Peripheral giant cell granuloma (giant cell epulis) in two dogs   总被引:1,自引:0,他引:1  
  相似文献   
57.
A 12-year-old intact female llama was euthanized following acute onset of spastic tetraparesis and recumbency with inability to rise. Postmortem examination revealed caudal cervical spinal cord compression due to a mass within the ventral spinal canal arising from the C6-C7 intervertebral disk space and attached to an irregularly thickened annulus fibrosis. On histopathologic examination, the mass was composed of amorphous acellular basophilic to amphophilic material admixed with irregularly arranged collagen bundles. The amorphous material was metachromatic and contained multiple small foci of markedly vacuolated round cells, characteristic of origin from the nucleus pulposus. Severe necrosis of all white matter tracts with astrocytic reaction was present in the overlying spinal cord segment. Ascending and descending Wallerian degeneration and dissecting interstitial astrogliosis were present within white matter tracts above and below the lesion, respectively. The diagnosis was compressive myelopathy due to chronic extrusion of the nucleus pulposus of the C6-C7 intervertebral disk. To the authors' knowledge, this is the first report of intervertebral disk disease in a camelid.  相似文献   
58.
A retrospective study examined data regarding equine cutaneous and mucocutaneous neoplasms submitted to the Veterinary Diagnostic Laboratory at Oregon State University in a 3.5-year period. A total of 536 neoplasms were identified, accounting for 30% of the total equine pathology submissions. Sarcoid, squamous cell carcinoma, melanocytic tumors, papillomas, and mast cell tumors were the most common neoplasms, constituting 87.5% of all cutaneous neoplasms. Sarcoids represented 51.4% of all neoplasms and 15.18% of total equine accessions. Sarcoid was most common in paints, quarter horses, and Arabians, and was the only common tumor in donkeys and mules. Mean age at diagnosis of equine sarcoid was 9 years. Squamous cell carcinoma constituted 18.3% of all neoplasms and 5.41% of total equine accessions. Ocular squamous cell carcinoma was most common in paints and quarter horses, and penile/preputial squamous cell carcinoma was most common in appaloosas and quarter horses. The mean age of horses with ocular squamous cell carcinoma (13 years) and squamous cell carcinoma of the skin (15 years) was significantly less (P < 0.5) than that of horses with squamous cell carcinoma of the penis and prepuce (21 years) or vulva, anal, and perianal skin (19 years). Findings suggest that equine sarcoid and squamous cell carcinoma occur more frequently in the Pacific Northwest than in the northeastern United States.  相似文献   
59.
Prevalence and type of neoplastic disease were determined in 551 camelid submissions (368 alpacas [Lama pacos], 180 llamas [Lama glama], and 3 cases in which species was not identified) over a 5-year period. Forty neoplasms were identified in 38 animals (6.9%). Prevalence of neoplasia in llamas was higher (11%) than in alpacas (4.9%). Mean age of camelids with neoplasia was 9.42 +/- 4.9 years. Mean age of alpacas with neoplasia (5.48 +/- 3.7 years) was significantly less than of llamas with neoplasia (12.53 +/- 3.2 years; P < 0.001). Cutaneous and mucocutaneous fibroma/fibropapilloma was most common (10 animals), followed by cutaneous and mucocutaneous squamous cell carcinoma (6 animals), disseminated lymphoma (5 animals), and fibrosarcoma (4 animals). Four of 5 animals with lymphoma were alpacas, aged 0.21 to 4 years. Lymphoma occurred in 1 aged llama (15 years). Disseminated carcinoma and adenocarcinoma occurred in 4 llamas and 2 alpacas, and included biliary (2), gastrointestinal (2), mammary gland (1), and unknown (1) origin. Mean age of camelids with any type of carcinoma or adenocarcinoma (12.36 +/- 2.8 years) was significantly greater than that of camelids with lymphoma (4.24 +/- 6.2 years; P = 0.02). Results indicate that neoplasia is relatively common in camelids and that there are differences between llamas and alpacas as regards prevalence of neoplasia, tumor types, and age at diagnosis.  相似文献   
60.
Muscular pseudohypertrophy was diagnosed in the cervical musculature of a full-term crossbred Simmental fetus delivered by fetotomy. Only head and cervical regions were submitted for pathologic examination; the rest of the fetal body was reportedly normal. The neck musculature of the fetus was markedly deformed by 23 cm and 18 cm in diameter, firm, spherical masses that consisted of enlarged and pale left splenius and right serratus ventralis cervicis muscle, respectively, covered by intact skin. Additionally, lipomatous masses were present within the cervical vertebral canal, compressing the spinal cord. Microscopically, the prominent muscular enlargement was due to massive adipose and fibrous connective tissue replacement of atrophic muscle. Focal myelodysplasia and astrocytosis affecting the grey matter was detected in the mid-cervical region of the spinal cord, accompanied by degeneration in the ascending and descending tracts of the remaining cord segments. Abnormal spinal cord development as a result of severe spinal cord compression by the lipomatous masses within the spinal canal leading to replacement of muscle by fat and fibrous tissue was considered to be the cause of the muscular malformation in this fetus.  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