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   1537篇
  免费   57篇
  国内免费   4篇
耳鼻咽喉   7篇
儿科学   47篇
妇产科学   30篇
基础医学   210篇
口腔科学   13篇
临床医学   61篇
内科学   343篇
皮肤病学   4篇
神经病学   166篇
特种医学   143篇
外科学   199篇
综合类   1篇
预防医学   24篇
眼科学   28篇
药学   106篇
中国医学   5篇
肿瘤学   211篇
  2022年   5篇
  2021年   4篇
  2020年   12篇
  2019年   19篇
  2018年   17篇
  2017年   22篇
  2016年   25篇
  2015年   35篇
  2014年   39篇
  2013年   54篇
  2012年   85篇
  2011年   85篇
  2010年   52篇
  2009年   41篇
  2008年   85篇
  2007年   95篇
  2006年   76篇
  2005年   82篇
  2004年   69篇
  2003年   81篇
  2002年   96篇
  2001年   13篇
  2000年   15篇
  1999年   23篇
  1998年   28篇
  1997年   25篇
  1996年   24篇
  1995年   25篇
  1994年   26篇
  1993年   29篇
  1992年   15篇
  1991年   22篇
  1990年   24篇
  1989年   17篇
  1988年   14篇
  1987年   13篇
  1986年   22篇
  1985年   25篇
  1984年   20篇
  1983年   14篇
  1982年   10篇
  1981年   22篇
  1980年   20篇
  1979年   9篇
  1978年   7篇
  1977年   11篇
  1976年   5篇
  1975年   6篇
  1974年   4篇
  1972年   4篇
排序方式: 共有1598条查询结果,搜索用时 16 毫秒
1.
Objective Acetylcholine (ACh) use in patients with bronchial asthma (BA) is contraindicated. We examined the clinical usefulness and safety of ACh spasm provocation tests in rest angina patients with BA. Patients The study subjects were 495 rest angina patients (mean age: 64.4±10.9 years old, male: 81.0%). Organic stenosis was found in 69 patients (13.9%). Methods We investigated 495 rest angina patients who underwent ACh spasm provocation tests. ACh was injected in incremental doses of 20/50/100/200 μg into the left coronary artery and 20/50/80 μg into the right coronary artery. Provoked positive spasm was defined as transient ≥90% luminal narrowing and usual chest pain or ischemic electrocardiogram changes. Results Among 495 rest angina patients, 13 (2.6%) were complicated with BA. Eleven patients with BA were controlled under medications, and two patients had a history of medication for BA. The clinical characteristics were not markedly different between rest angina patients with and without BA. The rate of multi-vessel spasm was markedly higher in patients with BA than that in those without BA. No complications during ACh spasm provocation tests were recognized in rest angina patients with BA, whereas major complications in those without BA were observed in eight patients including two ventricular fibrillations, three non-sustained ventricular tachycardias, and three shocks. We were able to perform all 495 ACh spasm provocation tests without any irreversible complications, while electrical defibrillation was necessary for 2 patients without BA. Conclusion We were able to perform ACh spasm provocation tests in rest angina patients with BA irrespective of the off-label use of ACh.  相似文献   
2.
BACKGROUND: Calcium phosphate cement (CPC) hardens in situ to form hydroxyapatite and has been used in dental and craniofacial restorative applications. However, when CPC was used in periodontal osseous repair, tooth mobility resulted in the fracture and exfoliation of the brittle CPC implant. The objective of the authors' study was to develop a strong and nonrigid CPC to provide compliance for tooth mobility without fracturing the implant. METHODS: The authors used tetracalcium phosphate, dicalcium phosphate anhydrous and biopolymer chitosan to develop a strong and nonrigid CPC. They used a powder:liquid ratio of 2:1, compared with the 1:1 ratio of a previously developed nonrigid CPC control. Specimens were characterized using a flexural test, scanning electron microscopy and powder X-ray diffraction. RESULTS: After 28 days of immersion, the new cement had a flexural strength (mean +/- standard deviation; n = 6) of 5.2 +/- 1.0 megapascals, higher than 1.8 +/- 1.5 MPa for the control (P < .05) and overlapping the reported strengths of sintered hydroxyapatite implants and cancellous bone. This cement showed a high ductility with a strain at peak load of 6.5 +/- 1.3 percent, compared with 4.4 +/- 1.9 percent for the control; both were 20-fold higher than the 0.2 percent of the conventional CPC. Nanosized hydroxyapatite crystals, similar to those in teeth and bones, were formed in the cements. CONCLUSIONS: The new nonrigid cement, containing nanohydroxyapatite crystals, possessed a high ductility and superior fracture resistance. This strong, tough and nonrigid CPC may be useful in periodontal repair to provide compliance for tooth mobility without fracture. CLINICAL IMPLICATIONS: The results of this study may yield the first self-hardening and nonrigid hydroxyapatite composite with high strength and durability and large deformation capability to be useful in the regeneration of periodontal osseous defects.  相似文献   
3.
4.
Graefe's Archive for Clinical and Experimental Ophthalmology - The aim of this study was to analyze choroidal structures in healthy subjects and patients with/without diabetic macular edema...  相似文献   
5.
A less invasive transsphenoidal approach with a keyhole dural opening for intrasellar arachnoid cysts is described. This approach was used to address seven sellar cystic lesions with suprasellar extension; they were six intrasellar arachnoid cysts (IACs) and one Rathke’s cleft cyst (RCC). In all cases, preoperative MRI revealed cerebrospinal fluid (CSF) intensity on both T1- and T2-weighted images. On preoperative contrast-enhanced MRI, five of the six IACs manifested posterior displacement of the flattened pituitary gland toward the dorsum sellae; one of the six IACs and the RCC exhibited a flattened pituitary gland on the anterior surface of the cyst. Wide cyst cisternostomy through a keyhole dural opening was carried out safely using a microscope with the support of a thin angled endoscope (30° and/or 70°, diameter 2.7 mm). As we aimed to avoid iatrogenic injury of the pituitary function, we found it difficult to obtain a sufficiently wide and precise opening of the cyst wall when the pituitary gland was located on the anterior surface of the cyst wall. Our approach facilitates safe cyst cisternostomy as wide as that obtainable by transcranial manipulation. In addition, CSF leakage is prevented by dural plasty using the fascia lata and stitching with 6-0 monofilament sutures. This technique can be adapted to address various sellar cystic lesions. However, as the posterior or anterior displacement of the normal pituitary gland in the presence of IACs or RCCs, respectively, affects the width of the cyst opening, our technique is more suitable for IACs than RCCs.  相似文献   
6.
7.
8.
9.
10.

Purpose  

To determine cellular viability of lung parenchyma and neoplastic cells in areas of ground-glass opacity (GGO) on computed tomography (CT) images immediately after pulmonary radiofrequency ablation (RFA) in rabbits.  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