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   534篇
  免费   18篇
  国内免费   3篇
耳鼻咽喉   4篇
儿科学   14篇
妇产科学   1篇
基础医学   56篇
口腔科学   2篇
临床医学   65篇
内科学   223篇
皮肤病学   13篇
神经病学   17篇
特种医学   7篇
外国民族医学   1篇
外科学   38篇
综合类   14篇
预防医学   38篇
眼科学   11篇
药学   27篇
中国医学   5篇
肿瘤学   19篇
  2023年   7篇
  2022年   18篇
  2021年   24篇
  2020年   17篇
  2019年   19篇
  2018年   18篇
  2017年   5篇
  2016年   10篇
  2015年   10篇
  2014年   9篇
  2013年   11篇
  2012年   29篇
  2011年   28篇
  2010年   20篇
  2009年   29篇
  2008年   37篇
  2007年   26篇
  2006年   30篇
  2005年   35篇
  2004年   43篇
  2003年   54篇
  2002年   34篇
  2001年   7篇
  2000年   4篇
  1999年   3篇
  1997年   6篇
  1996年   1篇
  1995年   3篇
  1994年   1篇
  1993年   1篇
  1992年   3篇
  1991年   2篇
  1990年   3篇
  1989年   2篇
  1987年   3篇
  1985年   1篇
  1984年   1篇
  1967年   1篇
排序方式: 共有555条查询结果,搜索用时 15 毫秒
11.
The purpose of this study was to investigate the effect of dietary vitamin E and vitamin C, probiotics mixture and protein level and their combination on semen quality and immunohistochemical study of some pituitary hormones in male broiler breeders. One hundred and eighty male broiler breeders 65 weeks old were divided into six groups by completely randomized design. The birds were subjected to zinc-induced molt by mixing zinc oxide at the rate of 3000 mg/kg in the feed. After molting, one group was fed control diet (CP16%). The other groups were fed vitamin E (100 IU/kg), vitamin C (500 IU/kg), probiotics (50 mg/L of drinking water), protein (CP14%) and combination of these components. These treatments were given for five weeks. After the feeding period, semen samples were taken and analyzed for semen volume, sperm concentration, motility and dead sperm percentage. Pituitary samples were collected from three birds per replicate and were processed for immunohistochemical study. The results of semen quality parameters revealed that semen volume and sperm motility were significantly high in the vitamin E fed group, while the dead sperm percentage decreased significantly in the vitamin C group. The morphometric analysis revealed that compared to other groups, vitamin E caused a significant increase in the size and area of FSH, LH gonadotropes and lactotropes. These results showed that vitamin E alone may play some role in the enhancement of semen quality and growth of gonadotropes and lactotropes.  相似文献   
12.
Acute pulmonary embolism in elderly: clinical characteristics and outcome   总被引:6,自引:0,他引:6  
OBJECTIVE: To evaluate the clinical characteristics and outcome of acute pulmonary embolism in elderly in comparison to the younger patients. METHODS: Study population consisted of 136 patients with a confirmed diagnosis of acute pulmonary embolism. Clinical characteristics and thromboembolic risk factors were analyzed between the elderly (> or =65 years of age) and the younger (<65 years of age) patients. In-hospital mortality was used as a measure of outcome. RESULTS: Elderly group consisted of 70 patients (age 76.4+/-8.3 years, range 65-96 years; females 58%) and younger group of 66 patients (age 48.5+/-12 years, range 18-64 years, females 59%). Syncope was more frequent in elderly group (19% vs. 6%, P=0.03) but the symptoms of shortness of breath and pleuritic chest pain were not significantly different between groups. Malignancy was the most common risk factor for thrombo-embolism, but immobilization predominated among patients in elderly group (21% vs. 6%, P=0.01). Tachycardia was common in younger patients compared to the elderly. Ventilation-perfusion scan was used more commonly in younger patients (76% vs. 57%, P=0.02), whereas, helical computed-tomography scan was used equally in both groups. Most of the patients had lower extremity duplex study (97% in each group). Inferior vena cava filter placement was common and thrombolytic therapy rare among elderly patients. Patients in elderly group had higher in-hospital mortality (17% vs. 5%, P=0.02). CONCLUSIONS: Syncope is a more frequent presenting symptom and immobilization a common risk factor in elderly patients with acute pulmonary embolism. In addition, they have higher in-hospital mortality.  相似文献   
13.
14.
15.
16.
17.
Endovascular stent grafting of descending thoracic aortic aneurysms   总被引:1,自引:0,他引:1  
Gowda RM  Misra D  Tranbaugh RF  Ohki T  Khan IA 《Chest》2003,124(2):714-719
The treatment of descending thoracic aortic aneurysms using endovascular stents is one of the more recent advances in treatment and is receiving increasing attention as it is a less invasive alternative to open surgical repair. Although the technology is still primitive, significant improvements have lately been made in the design and deployment of the endovascular stent-grafts. Aortic stent-grafts were used initially to exclude abdominal, and later thoracic, aortic true and false aneurysms. These prostheses have been increasingly used to treat aneurysms, dissections, and traumatic ruptures of the descending thoracic aorta with good early and mid-term outcomes. Although the long-term outcome of patients with aneurysms of the descending thoracic aorta after stent graft implantation has not been investigated, continued refinement of the endovascular approaches has decreased the need for conventional open thoracic aortic aneurysm repair, especially in patients who are at a high risk for standard surgery because of advanced age or the presence of comorbid diseases. The placement of endoluminal stent-grafts to exclude the dissected or ruptured site of thoracic aortic aneurysms is a technically feasible and relatively safe procedure. With the rapid development of endovascular approaches, the treatment of the descending thoracic aortic aneurysms might alter even more, but an extended follow-up is necessary to determine the longer term outcome. Historical perspectives, advantages, device considerations, complications, and current perspectives of the endovascular stent grafting of the descending thoracic aortic aneurysms are elaborated on.  相似文献   
18.
Cardiology professionals have used social media platforms such as Twitter to gain exposure to new research, network with experts, share opinions, and engage in scientific debates. The power of social media to communicate openly, with wide-reaching access worldwide, and at a rate faster than ever before makes it a formidable force and voice. However, evolving individual and institutional use has resulted in uncertainty for all parties on how to optimally advance this newer digital frontier. Thus, the purpose of this paper is to: 1) introduce the basics of social media usage (with the focus on Twitter); 2) provide perspective on best social media practices in academic and clinical cardiovascular medicine; and 3) present a vision for social media and the future of cardiovascular medicine.  相似文献   
19.
OBJECTIVE: The objectives of this study were to determine myocardial injury in patients with septic shock by measuring serum cardiac troponin I (cTnI), to evaluate relationship between elevated cTnI and myocardial dysfunction and to determine if cTnI is a predictor of outcome in these patients. METHODS: Thirty-seven consecutive patients with septic shock were included in the study. Serum cTnI was measured at study entry and after 24 and 48 h. Transthoracic echocardiogram, electrocardiogram and regular biochemical and hemodynamic assessments were performed. RESULTS: Sixteen (43%) patients had elevated serum cTnI. These patients had higher need for inotropic/vasopressor support (94% vs. 53%, p=0.018), higher APACHE II score (28 vs. 20, p=0.004), higher incidence of regional wall motion abnormalities on echocardiography (56% vs. 6%, p=0.002), lower ejection fraction (46% vs. 62%, p=0.04) and higher mortality (56% vs. 24%, p=0.04) compared to normal cTnI patients. By multiple logistic regression analysis, serum cTnI and APACHE II score were independent predictor of death and length of stay in intensive care unit. Serum cTnI, APACHE II score, anion gap and serum lactate were independent predictor of need for inotropic/vasopressor support. Receiver-operating characteristics of serum cTnI as a predictor of death in septic shock were significant. The elevated serum level of cTnI correlated with the lower left ventricular ejection fraction (p<0.001). CONCLUSIONS: Myocardial injury can be determined in patients with septic shock by serum cTnI. Serum cTnI concentration correlates with myocardial dysfunction in septic shock. High serum cTnI predicts increased severity of sepsis and higher mortality. A close monitoring of patients with septic shock and elevated levels cTnI is warranted.  相似文献   
20.
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