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   6662篇
  免费   274篇
  国内免费   8篇
林业   230篇
农学   343篇
基础科学   82篇
  825篇
综合类   362篇
农作物   247篇
水产渔业   197篇
畜牧兽医   3688篇
园艺   105篇
植物保护   865篇
  2023年   31篇
  2022年   41篇
  2021年   56篇
  2020年   80篇
  2019年   86篇
  2018年   100篇
  2017年   101篇
  2016年   112篇
  2015年   93篇
  2014年   131篇
  2013年   490篇
  2012年   295篇
  2011年   348篇
  2010年   173篇
  2009年   172篇
  2008年   331篇
  2007年   318篇
  2006年   270篇
  2005年   271篇
  2004年   285篇
  2003年   253篇
  2002年   247篇
  2001年   234篇
  2000年   215篇
  1999年   195篇
  1998年   56篇
  1997年   53篇
  1996年   57篇
  1995年   62篇
  1994年   40篇
  1993年   46篇
  1992年   105篇
  1991年   116篇
  1990年   133篇
  1989年   108篇
  1988年   101篇
  1987年   84篇
  1986年   67篇
  1985年   71篇
  1984年   67篇
  1983年   44篇
  1982年   30篇
  1981年   41篇
  1980年   44篇
  1979年   45篇
  1975年   25篇
  1974年   25篇
  1973年   26篇
  1972年   35篇
  1971年   32篇
排序方式: 共有6944条查询结果,搜索用时 11 毫秒
51.
The influence of infection with Ehrlichia phagocytophila (EP) on serum thyroid hormone concentrations and on antipyrine (25 mg/kg of body weight, IV) plasma elimination and urinary metabolite excretion was studied in castrated male dwarf goats. Mean thyroid hormone concentrations moderately decreased in EP-infected goats, with maximal decrease in total and free triiodothyronine and thyroxine serum concentrations of 56, 64, 23, and 19%, respectively. The estimated pharmacokinetic values of antipyrine (AP) in EP-infected goats were similar to those in the goats when healthy. However, glucuronidation of the AP-metabolites 3-hydroxymethyl-AP, 4,4'-dihydroxy-AP, and 4-hydroxy-AP was reduced during the febrile episode of the acute-phase response to EP infection.  相似文献   
52.
The effects of fine suture materials on corneal wound healing in the dog were studied. In 20 dogs, standardized perforating perilimbal clear corneal wounds were made and closed with either monofilament Polyglactin 910 or nylon. Five dogs each were euthanized 8,12,16, and 21 days postoperatively. Results of gross, biomicroscopic, and histologic examinations at 8,12,16, and 21 days showed nylon and Polyglactin 910 to cause similar inflammatory responses. Epithelialization and suppuration around the suture tracts were observed more frequently when Polyglactin 910 was used. Both materials were associated with a foreign body (granulomatous) response. There was no loss of wound integrity with either material. Strengths of the incised corneal tissues with and without the sutures intact were determined. At day 16 postsurgery, there was a statistically significant difference in tissue strengths between cases in which sutures were and were not intact. This difference was not apparent at 21 days postsurgery, which suggested that the suture dependent phase ends between the 16th and 21st postsurgical days. In addition, at day 16 there was no statistical difference between the tissue strength of wounds sutured with nylon or Polyglactin 910. Corneal suture materials studied should remain in place for at least 16 days, and absorbable material is only appropriate if it retains tensile strength for 16 days.  相似文献   
53.
Pellets of three types of roughage were fed to veal calves, to determine their effect on the frequency of lesions (erosions or ulcers) of the abomasal mucosa. The number was increased in the calves fed roughage. Pellets produced from corn silage caused a greater number of lesions than pellets produced from barley straw or lucerne hay. It is concluded that the nature of the roughage plays a role in the pathogenesis of abomasal lesions.  相似文献   
54.
55.
Instructions on how to debone and stuff a turkey are available, but what is the best way to close it up? A randomised trial involving 15 turkeys was performed in order to evaluate skin disruption scores and cosmetic outcomes following the use of different suture patterns. Turkeys were deboned, stuffed and cooked according to guidelines of the US Department of Agriculture Food Safety and Inspection Services. After stuffing, they were randomly assigned to one of five closure groups: simple continuous Lembert; simple continuous Cushing; simple continuous Utrecht; simple continuous; or staples. Turkeys were cooked at 180 °C for two hours ensuring core temperature reached 75 °C. Suture line integrity was evaluated after removal of the sutures and the cosmetic aspect was graded. Before cooking, the Utrecht pattern and skin staples offered the best cosmetic result. After removal of the sutures, the skin remained intact only in the stapled group. All other suture patterns disrupted the skin after removal of the sutures, rendering the turkey less cosmetically appealing for serving. Closure of a stuffed turkey was best performed using skin staples to achieve the best cosmetic results. Using this technique you will be able to impress family and friends at a Christmas dinner, and finally show them your surgical skills.  相似文献   
56.
57.
58.
59.
60.
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