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   5057篇
  免费   479篇
农学   7篇
综合类   4篇
农作物   2篇
水产渔业   2篇
畜牧兽医   5518篇
植物保护   3篇
  2024年   7篇
  2023年   90篇
  2020年   167篇
  2019年   2篇
  2018年   122篇
  2017年   134篇
  2016年   86篇
  2015年   140篇
  2014年   225篇
  2013年   242篇
  2012年   182篇
  2011年   209篇
  2010年   165篇
  2009年   247篇
  2008年   155篇
  2007年   96篇
  2006年   82篇
  2005年   83篇
  2004年   143篇
  2003年   147篇
  2002年   166篇
  2001年   160篇
  2000年   122篇
  1999年   118篇
  1998年   171篇
  1997年   179篇
  1996年   158篇
  1995年   162篇
  1994年   139篇
  1993年   150篇
  1992年   176篇
  1991年   151篇
  1990年   187篇
  1989年   133篇
  1988年   114篇
  1987年   150篇
  1986年   59篇
  1985年   80篇
  1984年   83篇
  1983年   79篇
  1982年   35篇
  1981年   14篇
  1980年   8篇
  1979年   3篇
  1978年   2篇
  1977年   3篇
  1976年   2篇
  1956年   2篇
  1955年   2篇
  1954年   1篇
排序方式: 共有5536条查询结果,搜索用时 15 毫秒
141.
Acetabular angles (AAs) and dorsal acetabular rim angles acquired by computed tomographic (CT) imaging have been used to assess patient response to juvenile pubic symphysiodesis surgery. The purpose of this study was to evaluate the effects of patient positioning and slice selection on these angles, and an attempt was made to devise a repeatable method of measuring these angles that would eliminate positioning effects. We found significant variation in AAs with small differences in pelvic tilt and slice selection. Dorsal acetabular rim angles were not affected. As a result of positioning differences from one CT study to the next, every attempt should be made to standardize pelvic tilt, or eliminate its effect on AAs by standardizing gantry angle in relation to an anatomic landmark that will not change over time. The floor of the sacral vertebral canal may be a reasonable landmark for this purpose and deserves further study.  相似文献   
142.
Objective: Correlate the necropsy diagnosis with the history, diagnostic findings, and clinical course of dyspneic cats with primary lung parenchymal disease. Design: Retrospective study. Setting: Matthew J. Ryan Veterinary Hospital of the University of Pennsylvania. Animals: Client‐owned cats over 6 months of age hospitalized in the Intensive Care Unit (ICU) with a primary problem of respiratory distress that had pulmonary parenchymal disease on thoracic radiographs, and a complete necropsy. Interventions: None. Measurements and main results: Cats included were assigned into 2 groups based on the pulmonary histopathology: inflammatory (n=8) and neoplastic (n=7) disease. No statistical difference was found between the groups with regard to age, body weight, clinical signs, duration of clinical signs, physical examination findings, thoracic radiography, duration of hospitalization, treatment, and outcome. Cats with neoplasia had a statistically higher mean total white blood cell count (26.60 k/μL±10.41) than those with inflammatory lung disease (11.59 k/μL±4.49; P=0.026). Cats with bacterial or viral pulmonary disease had a significantly shorter median duration of illness (5 days, range 1–7 days) than all other cats (30 days, range 7–365 days; P=0.0042). Ultrasound guided pulmonary fine‐needle aspiration (FNA) provided an accurate diagnosis in 5/5 cases. Conclusions: Forty‐seven percent of cats with pulmonary parenchymal disease had neoplasia. The clinical diagnosis was difficult to obtain ante‐mortem; lung FNA appeared to be the most helpful diagnostic tool in these cases.  相似文献   
143.
144.
145.
Twenty-six dogs with gastric dilatation-volvulus (GDV) were stabilized medically, followed by tube gastrostomy and gastropexy. In 13 dogs, a Heineke-Mikulicz pyloroplasty was also performed. Complications and recurrences were monitored during the immediate postoperative period and for 5 to 31 months thereafter. Barium gastrograms and contrast radiographs of the stomach were evaluated at week 1 and months 5 to 31. Significantly fewer dogs without pyloroplasty had complications during the immediate postoperative period. There were no differences in the long-term complication rates. Radiographic evaluations of the width of the pylorus, the size of the stomach, and the rate of gastric emptying showed no differences between dogs with and without pyloroplasty at any evaluation period. The Heineke-Mikulicz pyloroplasty increased the immediate postoperative complication rate after surgical fixation of the stomach for the treatment of GDV. It did not appear to influence the long-term outcome of the surgical treatment of this disease. The Heineke-Mikulicz pyloroplasty is not recommended in the treatment of GDV unless pyloric outflow obstruction can be demonstrated.  相似文献   
146.
A technique using a third bar and guide clamp was developed to permit reduction and stabilization of distal limb fractures with full pins and two connecting bars, one on each side of the bone. The system uses only single Kirschner clamps. Four distal limb fractures were stabilized using this technique. Closed reduction was used in three dogs to avoid devitalization of fragments and avoid contamination of a closed fracture. The fracture site stability achieved with this configuration allowed early return to weight bearing and rapid bone healing.  相似文献   
147.
148.
Mature ponies fitted with permanent ileal cannulas were used in two 3×3 Latin square experiments to quantify prececal, postileal and total tract digestion of N. In trial 1, corn, oats and sorghum were each fed with coastal Bermuda grass hay in 75:25 ratios. Apparent prececal digestibilities were similar (P>.05) and averaged 46.6%. By-difference procedures were employed to calculate digestibility of the cereal grain N only and apparent prececal N digestibility averaged 57.1%. In trial 2, a basal corn and hay diet was supplemented with cottonseed meal and soybean meal. Apparent total tract N digestibilities were similar (P>.05) across treatments, and prececal digestibility averaged 45.6%. By-difference calculations were used to determine digestibility of SBM and CSM N alone. Apparent prececal digestibility of SBM was 52.5% and was lower (P<.05) than 81.2% for CSM. It is possible that inadequate or excessive heat treatment of SBM affected enzymatic digestion. True digestibility of total rations fed in trial 2 was estimated by linear regression of nitrogen digested on nitrogen intake or N presented to the large intestine. True N digestibility of diets containing SBM and CSM was 54.7% and 69.4%, respectively.  相似文献   
149.
Objective: To determine if a secondary center of ossification (SCO) of the anconeal process is present in skeletally immature dogs that do not develop an ununited anconeal process (UAP). Study Design: Case series. Animals: Dogs 77–154 days of age with conditions other than developmental disease of the elbow (n=78 dogs; total elbows=100). Methods: Mediolateral radiographic projections of the elbow were reviewed for presence or absence of a SCO of the anconeal process. Results: A SCO was radiographically evident in 16% of elbows from breeds that have been reported to be affected by UAP. The appearance of the SCO was different to an UAP fragment. None of the elbows with SCO of the anconeal process developed UAP. A SCO was not present in any small breed dogs. Conclusions: A SCO of the anconeal process is uncommon in medium and large breed dogs and the presence of a SCO does not indicate that UAP will develop. Clinical Relevance: Because radiographic diagnosis of a SCO of the anconeal process and UAP lesions have distinct appearances, an earlier diagnosis of UAP is possible.  相似文献   
150.
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