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   419篇
  免费   37篇
  国内免费   2篇
林业   5篇
农学   2篇
  19篇
综合类   67篇
农作物   9篇
水产渔业   8篇
畜牧兽医   328篇
园艺   4篇
植物保护   16篇
  2023年   4篇
  2021年   5篇
  2020年   7篇
  2019年   3篇
  2018年   11篇
  2017年   11篇
  2016年   14篇
  2015年   7篇
  2014年   18篇
  2013年   29篇
  2012年   19篇
  2011年   21篇
  2010年   15篇
  2009年   18篇
  2008年   22篇
  2007年   10篇
  2006年   12篇
  2005年   18篇
  2004年   11篇
  2003年   8篇
  2002年   6篇
  2001年   12篇
  2000年   11篇
  1999年   4篇
  1998年   15篇
  1997年   10篇
  1996年   11篇
  1995年   11篇
  1994年   2篇
  1993年   3篇
  1992年   14篇
  1991年   9篇
  1990年   5篇
  1989年   9篇
  1988年   4篇
  1987年   3篇
  1986年   9篇
  1985年   10篇
  1984年   5篇
  1983年   3篇
  1982年   4篇
  1981年   5篇
  1979年   3篇
  1978年   2篇
  1977年   3篇
  1974年   2篇
  1972年   2篇
  1969年   3篇
  1968年   3篇
  1967年   2篇
排序方式: 共有458条查询结果,搜索用时 281 毫秒
101.
A 13‐year‐old Romanov sheep presented for evaluation of vaginal discharge, depression and anorexia. Blood work demonstrated mature neutrophilia and marked hyperlactatemia. Transrectal and transabdominal ultrasound revealed echogenic fluid (pus) within the uterus. Purulent uterine fluid culture yield Escherichia coli. A diagnosis of pyometra was made. After medical treatment without clinical improvement, an exploratory laparotomy was performed, and a 360‐degree uterine left horn torsion was identified with the pyometra and multiple corpora lutea on both ovaries. Ovariohysterectomy was performed and the ewe recovered uneventfully.  相似文献   
102.
103.
The objective of this study was to investigate differences on the endometrial immunoexpression of type I IFN receptor subunit 1 (IFNAR1) and oxytocin receptor (OTR) during the time of maternal recognition of pregnancy in sheep, when oestrus is synchronized with either prostaglandin analogues (group PG) or conventional progestagens (group P). Plasma progesterone was measured from day 0 to 21 post‐coitus (pc) (day 0 = day of oestrus). Immunohistochemistry was performed in samples of uterine horns from pregnant sheep on days 9pc, 13pc, 15pc, 17pc and 21pc to locate IFNAR1 and OTR expression in different endometrial compartments. Mean levels of plasma progesterone were different between treatments, obtaining higher levels in the PG group than in the P group (p < 0.05). Comparing days of pregnancy, IFNAR1 protein expression was different in the luminal epithelium (LE) (p < 0.05), while OTR was different in the LE and in the superficial glandular epithelium (SG) (p < 0.05). Temporal variation on the expression of both proteins from day 9pc to 21pc has been evidenced. IFNAR1 and OTR expression did not show significant differences between treatments. However, the response observed in the endometrium was highly inconsistent when prostaglandin analogues were used. Therefore, the protocol based on prostaglandin analogues still needs to be optimized before being considered as a better alternative to progestagens for oestrous synchronization in sheep.  相似文献   
104.
The objective of this study was to optimize protocols for the cryopreservation of sex‐sorted boar spermatozoa. In the experiment 1, we evaluated the effects of a standard boar sperm cryopreservation procedure (3% final glycerol concentration) on the in vitro characteristics of sex‐sorted sperm frozen at low sperm concentrations (20 × 106 sperm/ml; S20 group). Non‐sorted spermatozoa frozen at 1000 × 106 (C1000 group) and 20 × 106 (C20 group) sperm/ml were used as the freezing control groups. In experiment 2, the effects of different final glycerol concentrations (0.16%, 0.5%, 1.0%, 2.0% and 3.0%) on post‐thaw quality of the S20 and C20 groups were evaluated. In both experiments, the samples were evaluated prior to freezing (5°C) and at 30, 90 and 150 min after thawing. Experiment 1 indicated that freezing sperm at low concentrations decreased (p < 0.05) the total motility (TM) and progressive motility (PM) at 90 and 150 min after thawing regardless of whether the sperm were sorted or not. However, the sperm membrane integrity was not affected at any evaluation step. Inexperiment 2, significant effects on the TM and PM because of increased glycerol concentrations in the S20 and C20 groups were observed only at 90 and 150 min after thawing. The samples frozen in 3% glycerol showed lower (p < 0.05) TM and PM values when compared to those frozen in the presence of 0.5% and 1% glycerol. In both experiments, non‐sorted control samples displayed higher percentages of spermatozoa with damaged DNA than sorted spermatozoa. In conclusion, the optimization of cryopreservation conditions by decreasing the glycerol concentrations can improve post‐thaw motility of sex‐sorted spermatozoa frozen at low concentrations.  相似文献   
105.
Dogs do not appear to progress from obesity-induced insulin resistance to type 2 diabetes mellitus. Both postprandial hyperglycemia and postprandial hypertriglyceridemia have been proposed to cause or maintain beta cell failure and progression to type 2 diabetes mellitus in other species. Postprandial glucose, triglyceride, and insulin concentrations have not been compared in lean and obese dogs. We measured serum glucose, triglyceride, and insulin concentrations in nine naturally occurring obese and nine age- and gender-matched lean dogs. After a 24-h fast, dogs were fed half their calculated daily energy requirement of a standardized diet that provided 37% and 40% of metabolizable energy as carbohydrate and fat, respectively. Fasting and postprandial glucose and triglyceride concentrations were greater in the obese dogs (P < 0.001), although the mean insulin concentration for this group was five times greater than that of the lean group (P < 0.001). Most of the 0.6 mM (11 mg/dL) difference in mean postprandial glucose concentrations between lean and obese dogs was attributable to a subset of persistently hyperglycemic obese dogs with mean postprandial glucose concentrations 1.0 mM (18 mg/dL) greater than that in lean dogs. Persistently hyperglycemic obese dogs had lower triglyceride (P = 0.02 to 0.04) and insulin (P < 0.02) concentrations than other obese dogs. None of the dogs developed clinical signs of diabetes mellitus during follow-up for a median of 2.6 yr. We conclude that pancreatic beta cells in dogs are either not sensitive to toxicity because of mild hyperglycemia or lack another component of the pathophysiology of beta cell failure in type 2 diabetes mellitus.  相似文献   
106.
107.
This study was conducted to measure the concentration of cefquinome in the endometrium of mares after intrauterine treatment and to evaluate associated inflammation. Mares (n = 14) were randomly assigned to one of the following groups: (i) control (n = 4) were either not treated (n = 2) or received (n = 2) lactated Ringer's intrauterine for 1 or 3 days; (ii) treated mares (n = 10) received intrauterine cefquinome for 1 or 3 days. After at least 10 days had passed following the last treatment and ovulation, mares were given Prostaglandin F2α (PGF2α) and were randomly assigned to an alternate treatment. Endometrial biopsy samples were taken at 2, 8, 24 and 48 h, or at 4, 12 and 36 h, after the last treatment. Biopsy samples were taken at the same time points from control mares (n = 2) and lactated Ringer-treated mares (n = 2). Cefquinome concentrations were quantified using a high-performance liquid chromatography (HPLC) assay and inflammation was assessed using haematoxylin and eosin (H&E)-stained sections. Concentrations of cefquinome [559 (1 day) and 595 μg/g (3 days) at 2 h, and 403 (1 day) and 370 μg/g (3 days) at 4 h] were similar between treatment groups at 2 and 4 h after treatment (p > 0.05). At 8 h, as well as at 24 and 48 h, concentrations were greater in the 3-day group (17 vs 301 μg/g, 3 vs 80 μg/g and 0.1 vs 0.2 μg/g, respectively) (p < 0.05). No significant differences (p > 0.05) in the inflammatory response at 2–48 h after treatment were found between groups.  相似文献   
108.
Between June 2008 and March 2009, 87 cats in Australia developed symmetrical hindlimb ataxia, paraparesis, tetraparesis, paraplegia or tetraplegia in association with eating an imported, irradiated dry pet food. This communication reports the clinical signs and outcomes of those cats.  相似文献   
109.
The frequency of diabetes mellitus is described for cats that received veterinary care from two large feline-only clinics in Brisbane, Australia. Frequency was estimated using period prevalences (the proportion of the population at risk that was affected by diabetes at any point during a specified time period). Of the 12,576 study cats, 93 were affected with diabetes during the 5-year study period, resulting in a 5-year period prevalence of 7.4 per 1000 cats. Period prevalence was significantly higher in Burmese cats (22.4 cats per 1000) than domestic short and longhaired cats (7.6 cats per 1000) and the mean age at first diagnosis during the study period was significantly higher amongst Burmese cats (13.6 years) compared to domestic short and longhaired cats (10.9 years). Further investigations into the apparent predisposition of Burmese cats to diabetes mellitus are indicated.  相似文献   
110.
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