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   2452篇
  免费   124篇
  国内免费   26篇
耳鼻咽喉   14篇
儿科学   26篇
妇产科学   20篇
基础医学   300篇
口腔科学   36篇
临床医学   189篇
内科学   604篇
皮肤病学   22篇
神经病学   262篇
特种医学   188篇
外科学   352篇
综合类   8篇
一般理论   1篇
预防医学   135篇
眼科学   34篇
药学   230篇
中国医学   7篇
肿瘤学   174篇
  2024年   6篇
  2023年   35篇
  2022年   80篇
  2021年   143篇
  2020年   92篇
  2019年   85篇
  2018年   93篇
  2017年   71篇
  2016年   59篇
  2015年   98篇
  2014年   99篇
  2013年   122篇
  2012年   223篇
  2011年   191篇
  2010年   111篇
  2009年   100篇
  2008年   127篇
  2007年   165篇
  2006年   147篇
  2005年   107篇
  2004年   119篇
  2003年   81篇
  2002年   80篇
  2001年   32篇
  2000年   28篇
  1999年   15篇
  1998年   5篇
  1997年   10篇
  1996年   5篇
  1995年   3篇
  1994年   6篇
  1993年   2篇
  1992年   5篇
  1991年   3篇
  1989年   2篇
  1988年   2篇
  1987年   8篇
  1986年   6篇
  1985年   4篇
  1984年   2篇
  1982年   2篇
  1979年   4篇
  1977年   3篇
  1976年   4篇
  1975年   2篇
  1974年   2篇
  1971年   2篇
  1937年   1篇
  1930年   1篇
  1928年   1篇
排序方式: 共有2602条查询结果,搜索用时 15 毫秒
151.
BACKGROUND: Perioperative disturbances of microvascular blood flow and oxygenation in the intestinal tract have been hypothesized to play an important role in development of the multiple organ dysfunction syndrome. Herein, increased intra-abdominal pressure (IAP) has been identified as a key factor in the initiation of the pathophysiologic cascade. The authors hypothesized that increasing the IAP by intraperitoneal insufflation of carbon dioxide attenuates microvascular oxygen saturation in gastric mucosa. They tested this hypothesis in a prospective, observational study in 16 patients scheduled to undergo elective diagnostic laparoscopy. METHODS: The authors continuously assessed microvascular oxygen saturation in gastric mucosa by reflectance spectrophotometry. Simultaneously systemic oxygen saturation, heart rate, arterial blood pressure, and ventilation-derived variables were measured noninvasively. During general anesthesia and controlled mechanical ventilation, baseline values were obtained. Thereafter, the IAP was increased to 8 and 12 mmHg, respectively, followed by a control period after desufflation. RESULTS: The increase in IAP from baseline to 8 mmHg decreased microvascular oxygen saturation in gastric mucosa from 69+/-7% (mean +/- SD) to 63+/-8% at 8 mmHg IAP (P <0.05), with a further significant reduction to 54+/-13% at 12 mmHg IAP (P <0.01). Microvascular oxygen saturation in gastric mucosa recovered rapidly to baseline level (66 +/- 10%) after release of increased IAP. In striking contrast to regional mucosal oxygen saturation, systemic oxygenation did not change with either of the interventions. CONCLUSIONS: The results suggest that increasing intraabdominal pressure to moderate levels, commonly applied to induce a surgical pneumoperitoneum, decreases gastric mucosal oxygen saturation.  相似文献   
152.
153.
154.
One of the most important issue with which the mankind is confronting now is related to the quantitatively as well as qualitatively assurance of the food supply necessary for human species existence. In this context, by means of genetic engineering, modified genetic organisms were obtained. In the first stage, plant crops with high productivity and resistant against diseases and pests were obtained. After that, food products having modified organoleptic properties and high nutrition values were produced. The main problem concerning the long-term consumption of these products is their toxicity, which until now was not confirmed or denied. For this reason, tests are necessary to be made in order to stipulate and prevent these effects.  相似文献   
155.
BACKGROUND: The non-invasive assessment of postoperative spinal infections can pose a substantial diagnostic challenge, especially in the presence of orthopaedic devices. In contrast to white blood cell scanning, which is of limited use in the spine, the low uptake of 99mTc ciprofloxacin into normal bone marrow, combined with its claimed bacterial specificity, makes it, theoretically, an ideal candidate for evaluating postoperative spinal infections. AIM: This study aimed to evaluate 99mTc ciprofloxacin planar and single photon emission tomography (SPET) imaging in relation to microbiological diagnosis in the postoperative spine. METHODS: Only patients with a microbiologically confirmed diagnosis were included in this analysis. Planar imaging was performed at 1, 3 and 24 h, and SPET was performed at 3 h post-injection of 370 MBq 99mTc ciprofloxacin. Images were scored by two independent, certified, nuclear medicine physicians, blinded for the final diagnosis. RESULTS: Within the first 22 consecutive patients with microbiological diagnosis, there were nine deep infections. Sensitivity, specificity and accuracy at visual scoring were, respectively, 67%, 77%, 73% (1 h), 78%, 69%, 73% (3 h), and 56%, 92%, 77% (24 h) for planar imaging, and 100%, 54%, and 73% for SPET. CONCLUSION: In contrast to white blood cell scanning, SPET with Tc ciprofloxacin is sensitive in evaluating infections in the postoperative spine. Sensitivity is higher for SPET than for planar imaging. However, the results presented prove that its specificity is limited, especially in patients who have recently (< 6 months) undergone surgery. Taken this limitation into account, we advise planar and SPET imaging at 3 h post-injection and at an interval of at least 6 months after surgery to minimize the chance for false positives.  相似文献   
156.
157.
158.
159.
160.
Postictal delirium is an acute confusional state occurring during the immediate postictal phase in patients receiving electroconvulsive therapy that is characterized by motor agitation, disorientation, clouded consciousness, repetitive stereotyped movements, and poor response to commands. A schizophrenic patient with severe and recurrent postictal delirium is described. The possible role of the clozapine-electroconvulsive therapy combination in the occurrence of postictal delirium is discussed. Several management strategies were tried, with various degrees of success. Propofol proved to be effective in preventing agitation when used as induction agent or when administered at seizure end. However, propofol could not prevent a delirious state when only administered after the first signs of motor restlessness had emerged.  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