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   1308篇
  免费   46篇
  国内免费   1篇
林业   36篇
农学   24篇
基础科学   3篇
  186篇
综合类   204篇
农作物   43篇
水产渔业   123篇
畜牧兽医   667篇
园艺   17篇
植物保护   52篇
  2021年   10篇
  2020年   20篇
  2019年   13篇
  2018年   16篇
  2017年   24篇
  2016年   20篇
  2015年   13篇
  2014年   20篇
  2013年   70篇
  2012年   58篇
  2011年   71篇
  2010年   23篇
  2009年   45篇
  2008年   52篇
  2007年   64篇
  2006年   55篇
  2005年   66篇
  2004年   51篇
  2003年   61篇
  2002年   49篇
  2001年   28篇
  2000年   28篇
  1999年   17篇
  1998年   19篇
  1997年   19篇
  1996年   13篇
  1995年   14篇
  1994年   13篇
  1993年   13篇
  1992年   22篇
  1991年   31篇
  1990年   20篇
  1989年   20篇
  1988年   17篇
  1987年   27篇
  1986年   18篇
  1985年   16篇
  1984年   18篇
  1983年   8篇
  1981年   15篇
  1980年   6篇
  1979年   7篇
  1978年   11篇
  1977年   16篇
  1975年   8篇
  1974年   9篇
  1971年   6篇
  1969年   7篇
  1940年   5篇
  1937年   5篇
排序方式: 共有1355条查询结果,搜索用时 31 毫秒
1.
2.
PULMONARY MINERALIZATION IN FOUR DOGS WITH CUSHING'S SYNDROME   总被引:1,自引:0,他引:1  
The clinical and imaging features of four dogs with Cushing's syndrome and pulmonary mineralization are reviewed. Three dogs presented with a primary complaint of respiratory distress/dyspnea. Three dogs had pituitary dependent Cushing's syndrome, while the remaining one dog had iatrogenic Cushing's syndrome. Each dog had clinical features typical for Cushing's syndrome. Two of the dogs were euthanized due to progressive hypoxemia. In each dog, the serum calcium, phosphorous, blood urea nitrogen and creatinine were normal.
A generalized increase in unstructured interstitial pulmonary opacity with diffuse mineralization was noted on thoracic radiographs of all dogs. In one dog, an ill-defined nodular interstitial pattern of mineralization was present. Delayed bone phase scintigraphy using 99mTechnetium methylene diphosphonate documented generalized pulmonary uptake in two dogs. 99mTechnetium labeled microaggregated albumin lung perfusion scans were normal in these two dogs. 99mTc-MDP scintigraphy can provide useful information in diagnosing pulmonary mineralization in Cushingoid dogs.  相似文献   
3.
4.
5.
A 13-year-old neutered female Yorkshire terrier presented with a history of progressive episodic weakness and disorientation of 4 months duration. Physical and neurologic examinations were normal at presentation. Abdominal ultrasound revealed a mass involving the right adrenal gland. Standard planar scintigraphy was performed at 4, 18, and 24 hours after intravenous injection 185 MBq (5mCi) of 123I-labeled metaiodobenzylguanidine (123I-MIBG). An area of focal intense uptake was identified in the area of the right adrenal gland. A pheochromocytoma was confirmed histologically after surgical excision.  相似文献   
6.
Three dogs with multilobular osteochondrosarcoma of the skull were evaluated using magnetic resonance (MR) imaging. Spin echo T1, T2, proton weighted and post contrast T1W images were obtained with a 1.5 Tesla magnet. The MR imaging findings were similar in all three dogs with mixed signal intensities in the T1W, T2W and proton weighted images and fairly large areas of contrast enhancement in the post contrast T1W images. The extent of brain and soft tissue involvement were well delineated and provided useful information concerning surgical planning. MR imaging provided a useful method of evaluating dogs with skull tumors.  相似文献   
7.
Conadal production was studied in Loxechinus albus (Molina, 1782) maintained in cages suspended from a long-line in the Estero Castro, Chiloé for 3 mo during the austral summer. The sea urchins were fed either an artificial diet or a natural diet consisting of the macroalgae Macrocystis pyrifera and Ulva sp. Both diets were tested for four size ranges: 40–45, 50–55, 60–65 and 70–75 mm diameter. For all four size ranges, highest gonad production was with the artificial diet. Gonad production was greatest in the 40–45 mm individuals with an increase of about 1,400% and 750% in the wet weight of gonads in individuals fed the artificial and natural diet, respectively. With the three other size ranges, the increase was nearly 100% with the artificial diet and nearly 0% with the natural diet The gonad index showed similar patterns, being highest in the smallest individuals. Small individuals fed the artificial diet would provide the most cost effective aquaculture as production is best. It is not necessary to grow L. albus to the minimal legal size for fisheries (70-mm diameter) for cost effective gonad production.  相似文献   
8.
In four experiments a total of 288 individually fed pigs were given barley-based diets for about 100 days from about 20 kg liveweight. Fine grinding of barley increased the number and severity of oesophagogastric lesions. Pelleting a diet based on coarsely ground barley had a similar effect. Coarser grinding of the barley and substituting small proportions of oat husk, but not of bran, gave lower incidences and severities of lesions. The performance responses of the pigs differed and give a framework for deciding on the balance to be struck between optimal performance and the risk of lesion development.  相似文献   
9.
10.
Echinococcus granulosus worm excretory/secretory antigens (WES) were used in ELISA for diagnosis of E. granulosus infection in dogs and compared with protoscolex somatic antigens (PSM). Sera from 224 dogs were tested. There was no correlation between ELISA absorbance values and E. granulosus worm burdens using either antigen. There was a significant linear relationship between absorbance values of sera tested in the ELISA using WES (W-ELISA) and the ELISA using PSM (P-ELISA). However, there was a small but significant difference between the absorbance values of the sera tested against the two antigens. Western blot analysis of WES using sera from E. granulosus-infected and uninfected dogs revealed antigenic components of relative molecular mass (Mr) larger than 94,000, Mr 94,000-68,000 and Mr 43,000-39,000 in worms, and these were specific for E. granulosus and not identified in PSM; these antigenic differences may be responsible for differences in reactivity in ELISA. The sensitivities of W-ELISA and P-ELISA were 80.8% and 75.6%, respectively. The specificities of W-ELISA and P-ELISA were 93.7% and 97.9%, respectively. The reduced specificity in W-ELISA was mainly attributable to increased background reactivity of sera from Taenia hydatigena-infected dogs. Despite the reduction in specificity, both ELISAs are valuable epidemiological tools to determine the prevalence of antibody to E. granulosus in dog populations and to monitor the success of hydatid control campaigns.  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