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   559篇
  免费   16篇
林业   17篇
农学   13篇
  87篇
综合类   87篇
农作物   8篇
水产渔业   18篇
畜牧兽医   310篇
园艺   12篇
植物保护   23篇
  2021年   6篇
  2020年   5篇
  2019年   9篇
  2018年   6篇
  2017年   6篇
  2015年   5篇
  2014年   7篇
  2013年   8篇
  2012年   24篇
  2011年   23篇
  2010年   11篇
  2009年   18篇
  2008年   20篇
  2007年   29篇
  2006年   28篇
  2005年   22篇
  2004年   21篇
  2003年   18篇
  2002年   14篇
  2001年   15篇
  2000年   22篇
  1999年   15篇
  1998年   6篇
  1997年   6篇
  1996年   4篇
  1995年   7篇
  1994年   4篇
  1993年   5篇
  1992年   10篇
  1991年   21篇
  1990年   15篇
  1989年   9篇
  1988年   5篇
  1987年   11篇
  1986年   11篇
  1985年   4篇
  1984年   13篇
  1980年   4篇
  1979年   9篇
  1978年   6篇
  1977年   3篇
  1975年   6篇
  1974年   9篇
  1973年   4篇
  1972年   5篇
  1971年   6篇
  1970年   8篇
  1969年   7篇
  1968年   4篇
  1967年   4篇
排序方式: 共有575条查询结果,搜索用时 15 毫秒
61.
A 3-year-old Thoroughbred colt was presented for evaluation of azotemia and anorexia. Physical examination revealed a ureterolith in the left ureter, approximately 10 cm from the bladder, which was thought to obstruct urine flow by approximately 90% when viewed cystoscopically. Ultrasonographic examination of both kidneys revealed indistinct corticomedullary junctions, and the right kidney was more hyperechoic. A percutaneous biopsy of the right kidney revealed chronic interstitial nephritis with marked interstitial medullary fibrosis. Medical therapy consisting of IV fluids, sodium chloride PO, and ammonium chloride PO was initiated. Ureteroscopic electrohydraulic lithotripsy via a perineal urethrostomy was used to successfully remove the stone. Klebsiella oxytoca , which responded to oral enrofloxacin therapy, was cultured from the urine after surgery. Azotemia resolved and the horse resumed training.  相似文献   
62.
63.
64.
Six Holstein cows (averaging 475 kg body weight, 2.3 parities and 96 d in lactation) fitted with catheters in the hepatic portal vein, mesenteric vein and intercostalis posterior artery were exposed to treatments of thermal comfort environments with libitum or restricted (75% of ad libitum) DM intake and a thermal stress environment with ad libitum intake in two balanced 3 x 3 latin squares to evaluate effects of thermal stress on portal plasma flow and net fluxes of metabolites. Portal plasma flow was measured by administering a primed, continuous infusion of para-aminohippurate into a mesenteric vein and determining its concentration and dilution in portal vein plasma. Thermal stress treatment increased rectal temperatures and respiration rates. Dry matter intake decreased from thermal comfort ad libitum level (15.1 kg/d) to lower levels in thermal comfort restricted (11.5 kg/d) and thermal stress (11.1 kg/d) treatments. Portal plasma flow was related directly to level of DM intake, declining about 14% with thermal comfort restricted intake and thermal stress environment treatments compared with the thermal comfort restricted intake and thermal stress environment treatments compared with the thermal comfort ad libitum intake treatment. Net flux of alpha-amino N was reduced 20 and 35% by thermal comfort restricted intake and thermal stress treatments compared with the thermal comfort ad libitum intake treatment. Net fluxes of urea N, ammonia N and glucose were not affected by experimental treatments. A portion of the negative effects of thermal stress on milk production can be explained by decreased nutrient intake and decreased nutrient uptake by the portal-drained viscera of the cow.  相似文献   
65.
Litter in a room which had housed chickens and turkeys actively infected with velogenic viscerotropic Newcastle disease was no longer infectious for susceptible chickens placed there 10 to 14 days later.  相似文献   
66.
Deer mice (Peromyscus maniculatus) were trapped from a sand prairie at various distances from an adjacent battery lead reclamation plant. Analysis of liver, kidney, and bone for lead concentrations showed an increase of tissue lead concentrations over controls to a distance of approximately 400 m. Soil and plant lead concentrations roughly correlated with the findings in deer mouse tissues. At higher tissue lead concentrations, acid-fast staining intranuclear inclusions within renal tubular epithelial cells were an occasional finding.  相似文献   
67.
During the 1981 corn harvest season in Illinois and surrounding states, cold wet weather enhanced the growth of Fusarium graminearum, with resulting contamination by vomitoxin and, to a lesser extent, zearalenone. Of 342 feed samples analyzed, 274 contained vomitoxin at a concentration ranging from 0.1 to 41.6 ppm (mean, 3.1 ppm) and 40 samples contained zearalenone at a concentration ranging from 0.1 to 8 ppm (mean, 0.66 ppm). Animal health problems and reduced growth performance were observed mainly in swine fed vomitoxin-contaminated rations. The predominant clinical complaints, in decreasing frequency were: reproductive problems (50%), feed refusal (43%), reduced weight gain (25%), diarrhea (17%), death (14%), and emesis (11%).  相似文献   
68.
69.
One hundred eighty-five dogs with histologically confirmed, measurable malignant tumors were used in a study to determine the toxicity of the anthracycline antitumor antibiotic, doxorubicin, which was administered once or twice (at a 21-day interval) at the rate of 30 mg/m2 of body surface area, iv. During this study, 7 dogs died as a direct result of doxorubicin-induced toxicosis and 16 died as a direct result of the malignant neoplastic disease. Each dog was evaluated for signs of toxicosis for 3 weeks after the last dose was administered (15 dogs received 1 dose, 170 dogs received 2 doses) or until the dog died, whichever came first. The most common signs of toxicosis were vomiting, diarrhea, colitis, anorexia, and pruritus. The probability of doxorubicin-induced toxicosis decreased significantly (P less than 0.0001) in inverse relationship to body weight. Dogs with signs of toxicosis during the 21-day interval from administration of the first dose of doxorubicin were 17.2 times (P less than 0.01; 95% confidence interval; 5.5, 54.2) more likely to develop signs of toxicosis during the 21-day interval from the second dose of doxorubicin. The performance status of each dog was evaluated using a modified Karnofsky performance scheme; the only time the performance status was adversely affected to a significant extent by doxorubicin-induced toxicosis was during the 21-day period, starting with the second dose (P less than 0.0001).  相似文献   
70.
SUMMARY A case of vaginal prolapse in a South Australian Sea Lion is described. Conservative treatment proved unsuccessful, and an ovariohysterectomy was performed. Problems concerning anaesthesia, surgery and post-operative management of this marine species are discussed.  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