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   1174篇
  免费   73篇
  国内免费   9篇
耳鼻咽喉   11篇
儿科学   72篇
妇产科学   11篇
基础医学   102篇
口腔科学   31篇
临床医学   108篇
内科学   290篇
皮肤病学   21篇
神经病学   23篇
特种医学   248篇
外科学   107篇
综合类   59篇
预防医学   65篇
眼科学   20篇
药学   42篇
中国医学   9篇
肿瘤学   37篇
  2021年   4篇
  2020年   6篇
  2019年   11篇
  2018年   14篇
  2017年   10篇
  2016年   7篇
  2015年   19篇
  2014年   40篇
  2013年   66篇
  2012年   34篇
  2011年   32篇
  2010年   39篇
  2009年   66篇
  2008年   46篇
  2007年   60篇
  2006年   29篇
  2005年   35篇
  2004年   23篇
  2003年   17篇
  2002年   23篇
  2001年   17篇
  2000年   18篇
  1999年   15篇
  1998年   79篇
  1997年   54篇
  1996年   64篇
  1995年   44篇
  1994年   50篇
  1993年   44篇
  1992年   11篇
  1991年   5篇
  1990年   11篇
  1989年   40篇
  1988年   29篇
  1987年   26篇
  1986年   20篇
  1985年   12篇
  1984年   16篇
  1983年   15篇
  1982年   14篇
  1981年   20篇
  1980年   13篇
  1979年   8篇
  1978年   9篇
  1977年   16篇
  1976年   8篇
  1975年   11篇
  1973年   2篇
  1972年   1篇
  1955年   1篇
排序方式: 共有1256条查询结果,搜索用时 15 毫秒
1.
目的 探讨创伤后迟发性脑肿胀的临床特点、发病机制与治疗。方法 回顾性分析1998年1月~2005年6月年收治的17例迟发性脑肿胀患者的临床特点和救治情况。结果 所有颅脑损伤患者采用保守治疗后均有好转,但于伤后5-10d出现恶化,CT复查有脑肿胀,经加强综合脱水等治疗后16例治愈,1例死亡。结论 迟发性脑肿胀好发于对冲性额、颞叶挫裂伤伴明显蛛网膜下腔出血、硬膜下薄层血肿及早期CT有脑肿胀者。其发病机制可能与创伤后的迟发性脑血管痉挛、微循环障碍、静脉回流障碍及甘露醇作用下降等因素有关。此类患者病情隐蔽性强,应加强观察、积极行CT复查,如能早期明确诊断,保守治疗多数效果良好。  相似文献   
2.
Retrorenal colon: implications for percutaneous diskectomy   总被引:1,自引:0,他引:1  
Helms  CA; Munk  PL; Witt  WS; Davis  GW; Morris  J; Onik  G 《Radiology》1989,171(3):864-865
It has been recommended that computed tomography (CT) with the patient prone be performed in every patient undergoing percutaneous diskectomy; this would enable detection of a retrorenal location of the colon, which could interfere with the percutaneous procedure. In this evaluation of 346 prone CT studies, only one patient (0.29%) was found to have retrorenal or retropsoas bowel that would have been perforated at diskectomy. Because of this extremely low prevalence, the performance of prone CT in every patient undergoing percutaneous lumbar diskectomy is not believed to be necessary.  相似文献   
3.
4.
5.
6.
采用间接ELISA检测23名肾移植受者血清巨细胞病毒(CMV)抗体,共检出18名(78%)活动性CMV感染,其中10名(44%)为原发性感染。结果证实CMV-IgE和-IgA具有较好的血清学诊断价值,优于CMV-IgM。  相似文献   
7.
The beta-amyloid (Abeta) precursor protein (APP) is cleaved sequentially by beta-site of APP-cleaving enzyme (BACE) and gamma-secretase to release the Abeta peptides that accumulate in plaques in Alzheimer's disease (AD). GGA1, a member of the Golgi-localized gamma-ear-containing ARF-binding (GGA) protein family, interacts with BACE and influences its subcellular distribution. We now report that overexpression of GGA1 in cells increased the APP C-terminal fragment resulting from beta-cleavage but surprisingly reduced Abeta. GGA1 confined APP to the Golgi, in which fluorescence resonance energy transfer analyses suggest that the proteins come into close proximity. GGA1 blunted only APP but not notch intracellular domain release. These results suggest that GGA1 prevented APP beta-cleavage products from becoming substrates for gamma-secretase. Direct binding of GGA1 to BACE was not required for these effects, but the integrity of the GAT (GGA1 and TOM) domain of GGA1 was. GGA1 may act as a specific spatial switch influencing APP trafficking and processing, so that APP-GGA1 interactions may have pathophysiological relevance in AD.  相似文献   
8.
OBJECTIVE: The Lee-risk index [Lee-index] was developed to predict major adverse cardiac events [MACE]. However, age is not included as a risk factor. The aim was to assess the value of the Lee-index in vascular surgery patients among different age categories. METHODS: Of 2642 patients cardiovascular risk factors were noted to calculate the Lee-index. Patients were divided into four age categories; < or = 55 (n=396), 56-65 (n=650), 66-75 (n=1058) and > 75 years (n=538). Outcome measures were postoperative MACE (cardiac death, MI, coronary revascularization and heart failure). The performance of the Lee-index was determined using C-statistics within the four age groups. RESULTS: The incidence of MACE was 10.9%, for Lee-index 1, 2 and > or = 3; 6%, 13% and 20%, respectively. However, the prognostic value differed among age groups. The predictive value for MACE was highest among patients under 55 year (0.76 vs 0.62 of patients aged > 75). The prediction of MACE improved in elderly (aged > 75) after adjusting the Lee-index with age, revised risk of operation (low, low-intermediate, high-intermediate and high-risk procedures) and hypertension (0.62 to 0.69). CONCLUSION: The prognostic value of the Lee-index is reduced in elderly vascular surgery patients, adjustment with age, risk of surgical procedure, and hypertension improves the Lee-index significantly.  相似文献   
9.
AIM: The aim of this pilot study was an investigation on photodynamic therapy (PDT) whether it is a good alternative for treating periungual and subungual warts of the hands. STUDY DESIGN: Twenty patients (mean age: 30.5 years) with a total of 40 periungual and subungual warts were treated with PDT. A photosensitizer, 20%delta-aminolevulinic acid was applied on the warts. After a mean incubation time of 4.6 h (SD: 1.2), the warts were irradiated with the VersaLight for 5-30 min (15.2 +/- 4.3 min). RESULTS: After a mean of 4.5 treatments a mean clearance of 100% was achieved in 90% of the patients. One patient (5%) showed a clearance of 50% and another showed no improvement. The subungual or periungual location of the wart had no influence on the number of treatments or end result (P > 0.05). There were two recurrences during the mean follow-up period of 5.9 months (SD: 7.6). Besides mainly pain and hyperpigmentation, most treatments had no side-effects. CONCLUSION: PDT can offer a good alternative for treating periungual warts of the hands. Larger studies are indicated.  相似文献   
10.
OBJECTIVES: To directly compare the magnetic navigation system (MNS) guidewires with conventional guidewires in branching tortuous phantoms with operators of varying MNS and percutaneous coronary intervention experience. BACKGROUND: Vessel tortuosity, angulation, and side branches remain limiting factors in coronary interventions. The MNS addresses these limitations by precisely directing the tip of a magnetised guidewire in vivo aided by two permanent adjustable external magnets. METHODS: Crossing and fluoroscopy times of six operators were evaluated in five tortuous Perspex(R) phantom vessels in three consecutive attempts. Standard guidewire (SG) usage was unrestricted. Two 2nd generation magnetic guidewires (MG) were used. Failure was noted if the cross was unsuccessful within 5 min. RESULTS: The magnetic navigation was vastly superior to SG techniques with increasingly tortuous phantoms. It dramatically decreased both the crossing and fluoroscopy times with maximal reduction from 201.7 +/- 111 to 36.4 +/- 13 sec, P < 0.001 and 204.7 +/- 24 to 47.2 +/- 19 sec, P < 0.001, respectively. The MNS had a 98.8% procedural success rate compared to 68% with SG techniques. Moreover it considerably limited the amount of wire usage from 5.5 to 1.3. Operators with prior MG experience performed significantly better than those without, except in the simplest phantom where the difference was nonsignificant (33.8 +/- 13 sec vs. 41.7 +/- 17 sec, P = 0.2). CONCLUSION: MNS significantly reduces both the crossing and fluoroscopy times in tortuous coronary phantom models achieving excellent success rates with dramatic reductions in guidewire usage. Operators with prior MNS experience had an advantage over the inexperienced.  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