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   24980篇
  免费   1291篇
  国内免费   10篇
林业   912篇
农学   765篇
基础科学   154篇
  3632篇
综合类   3530篇
农作物   920篇
水产渔业   1352篇
畜牧兽医   13175篇
园艺   270篇
植物保护   1571篇
  2019年   250篇
  2018年   421篇
  2017年   509篇
  2016年   475篇
  2015年   342篇
  2014年   461篇
  2013年   974篇
  2012年   802篇
  2011年   959篇
  2010年   692篇
  2009年   672篇
  2008年   977篇
  2007年   921篇
  2006年   813篇
  2005年   738篇
  2004年   645篇
  2003年   705篇
  2002年   608篇
  2001年   805篇
  2000年   801篇
  1999年   634篇
  1998年   275篇
  1997年   286篇
  1995年   259篇
  1994年   227篇
  1993年   233篇
  1992年   425篇
  1991年   516篇
  1990年   434篇
  1989年   412篇
  1988年   400篇
  1987年   409篇
  1986年   363篇
  1985年   388篇
  1984年   339篇
  1983年   287篇
  1982年   244篇
  1979年   384篇
  1978年   289篇
  1977年   290篇
  1976年   300篇
  1975年   317篇
  1974年   332篇
  1973年   303篇
  1972年   290篇
  1971年   245篇
  1969年   289篇
  1968年   269篇
  1967年   326篇
  1966年   304篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
994.
995.
996.
997.
998.

Neonatal calf mortality is a major concern to livestock sector worldwide. Neonatal calf diarrhoea (NCD), an acute severe condition causes morbidity and mortality in calves. Amongst various pathogens involved in NCD, E. coli is considered as one of the major causes. The study was targeted to characterize E. coli isolates from neonatal calves for diarrhoeagenic Escherichia coli (DEC) types (pathotyping), antimicrobial resistance (AMR) profiling and to correlate with epidemiological parameters. From neonates, a total of 113 faecal samples were collected, out of that 308, lactose fermenting colonies were confirmed as E. coli. Pathotypable isolates (12.3%) were represented by STEC (6.1%), EPEC (2.9%), ETEC (1.9%), EAEC (0.9%) and EHEC (0.3%). Occurrence of STEC was more in non-diarrhoeic calves, whereas ETEC was observed more in diarrhoeic calves. EPEC occurrence was observed in both diarrhoeic and non-diarrhoeic calves. Fishers extract test showed no significant association for occurrence of DEC types to type of dairies, health status, species, breed, age and sex of neonatal calves. Two hundred and eighty isolates were tested for antimicrobial susceptibility. The isolates showed maximum resistance towards ampicillin (55.4%) followed by tetracycline (54.3%), while minimum resistance was observed towards meropenem (2.5%). Multidrug resistant E. coli isolates were found to be 139 (49.6%), and Extended-spectrum beta-lactamase (ESBL) producers were 120 (42.9%). DEC pathotypes like STEC, ETEC, EHEC and EAEC that are also multidrug resistant present in neonatal calves have zoonotic potential and hence are of public health significance.

  相似文献   
999.
This case report describes four horses with unilateral superficial or mid-stromal immune-mediated keratitis (IMMK) treated with a superficial keratectomy (SK) without a conjunctival graft. In two horses, the surgery was performed under general anaesthesia, and in two horses standing with sedation and local blocks. Results of this report show that SK is a viable treatment option in horses with chronic superficial and/or mid-stromal IMMK that can even be performed in the standing, sedated horse. When sufficient corneal tissue is removed, no recurrence is to be expected in the long-term follow-up (up to 31 months). In two horses, healing occurred without complications. Two horses developed a secondary bacterial infection post-operatively (Enterococcus faecalis and Staphylococcus aureus). In one case, this resulted in a pre-perforating melting corneal ulcer necessitating conjunctival pedicle graft surgery 13 days post keratectomy. In three horses, there was no recurrence of the IMMK with a long-term follow-up of 6–31 months. One case showed recurrence of IMMK in the cornea region surrounding the keratectomy 9 months after surgery.  相似文献   
1000.
The present report describes a case of cutaneous papillomatosis related to equine papillomavirus type 2 (EcPV2) with concomitant cutaneous habronemiasis. A 2-year-old female Pura Raza Española horse was referred for a dermatological evaluation because of the onset of cutaneous multifocal, nodular lesions on the face characterised by a warty and partially ulcerated overlying epidermis. Multiple biopsies were taken from these lesions, and cutaneous viral papillomas with a concomitant severe focal eosinophilic dermatitis with intralesional Habronematidae nematode larvae were diagnosed. Immunohistochemistry revealed papillomaviral capsid protein L1 in the epidermal proliferative lesion, confirming the presence of a productive infection. Rt-qPCR confirmed the presence of EcPV type 2. To the authors’ knowledge, this is the first report of EcPV2-related papillomas with concurrent habronemiasis.  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