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   5535篇
  免费   314篇
  国内免费   77篇
耳鼻咽喉   95篇
儿科学   71篇
妇产科学   85篇
基础医学   557篇
口腔科学   190篇
临床医学   526篇
内科学   1498篇
皮肤病学   55篇
神经病学   670篇
特种医学   279篇
外科学   905篇
综合类   5篇
预防医学   205篇
眼科学   51篇
药学   288篇
中国医学   8篇
肿瘤学   438篇
  2024年   13篇
  2023年   101篇
  2022年   182篇
  2021年   293篇
  2020年   219篇
  2019年   232篇
  2018年   244篇
  2017年   158篇
  2016年   224篇
  2015年   232篇
  2014年   274篇
  2013年   356篇
  2012年   506篇
  2011年   474篇
  2010年   263篇
  2009年   227篇
  2008年   293篇
  2007年   313篇
  2006年   254篇
  2005年   236篇
  2004年   229篇
  2003年   197篇
  2002年   143篇
  2001年   25篇
  2000年   11篇
  1999年   20篇
  1998年   36篇
  1997年   28篇
  1996年   22篇
  1995年   17篇
  1994年   15篇
  1993年   14篇
  1992年   16篇
  1991年   11篇
  1990年   10篇
  1989年   4篇
  1988年   3篇
  1987年   5篇
  1986年   5篇
  1984年   2篇
  1982年   4篇
  1978年   1篇
  1977年   1篇
  1973年   4篇
  1964年   1篇
  1962年   1篇
  1961年   1篇
  1957年   1篇
  1940年   1篇
  1905年   1篇
排序方式: 共有5926条查询结果,搜索用时 15 毫秒
41.
The network architecture of functional connectivity within the human brain connectome is poorly understood at the voxel level. Here, using resting state functional magnetic resonance imaging data from 1003 healthy adults, we investigate a broad array of network centrality measures to provide novel insights into connectivity within the whole-brain functional network (i.e., the functional connectome). We first assemble and visualize the voxel-wise (4 mm) functional connectome as a functional network. We then demonstrate that each centrality measure captures different aspects of connectivity, highlighting the importance of considering both global and local connectivity properties of the functional connectome. Beyond "detecting functional hubs," we treat centrality as measures of functional connectivity within the brain connectome and demonstrate their reliability and phenotypic correlates (i.e., age and sex). Specifically, our analyses reveal age-related decreases in degree centrality, but not eigenvector centrality, within precuneus and posterior cingulate regions. This implies that while local or (direct) connectivity decreases with age, connections with hub-like regions within the brain remain stable with age at a global level. In sum, these findings demonstrate the nonredundancy of various centrality measures and raise questions regarding their underlying physiological mechanisms that may be relevant to the study of neurodegenerative and psychiatric disorders.  相似文献   
42.

Introduction and hypothesis

Intravesical instillations of hyaluronic acid (HA) and chondroitin sulfate (CS) may lead to regeneration of the damaged glycosaminoglycan layer in interstitial cystitis/bladder pain syndrome (IC/BPS).

Methods

Twenty-two patients with IC/BPS received intravesical instillations (40?ml) of sodium HA 1.6% and CS 2.0% in 0.9% saline solution (IALURIL?, IBSA) once weekly for 8?weeks, then once every 2?weeks for the next 6?months.

Results

The score for urgency was reduced from 6.5 to 3.6 (p?=?0.0001), with a reduction in pain scores from an average of 5.6 to 3.2 (p?=?0.0001). The average urine volume increased from 129.7 to 162?ml (p?p?p?p?Conclusion The treatment appeared to be effective and well tolerated in IC/BPS in this initial experience.  相似文献   
43.
44.
p < 0.05) than in patients with parathyroid adenoma, and the mean tumor size was 2.9 cm (median 2.5 cm, range 1.5–4.5 cm). Twenty-eight operations were performed with resulting normalization of serum calcium levels for more than 6 months in 11 patients. Six patients presented prolonged postoperative hypocalcemia (2–10 months), and five patients had persistent HPT. Ten patients experienced recurrent disease; the median disease-free period was 24 months (range 4–72 months). None of the patients was treated with chemotherapy, one patient underwent radiation therapy (50 Gy in 25 sessions) but required reoperation for local recurrence 4 months later. Three patients are still alive (two with recurrence). Average survival was 40 months (median 31 months, range 11–131 months).  相似文献   
45.
OBJECTIVE: To verify the feasibility and compare the results of thoracoscopic sympathectomy under local anaesthesia (LA) and spontaneous breathing vs. general anaesthesia (GA) with one-lung ventilation. METHODS: Two groups of consecutive patients underwent one stage bilateral T2-T3 thoracoscopic sympathectomy under LA (n=15) and GA (n=30) by the same surgical team for treatment of primary palmar hyperhidrosis. The groups were homogeneous for relevant demographic, physiological and clinical data, including pulmonary function. In both groups, patient's satisfaction was evaluated 24h after surgery by a simple interview and scored into five grades (1=very poor to 5=excellent), while quality of life (QOL) was evaluated by SF-36 and Nottingham's Health Profile questionnaires before and 6 months after surgery. A cost comparison between groups concerning devices, drugs, global in operating room time, medical personnel and hospital stay was also carried out. RESULTS: No operative mortality was recorded. The overall in operating room time for the whole bilateral procedure under LA was 63.55+/-10.58 vs. 86.05+/-5.75 under GA (P<0.01) and temperature increased in all patients from a baseline of 25.42+/-0.56 up to 32.15+/-0.84 degrees C. All patients undergone LA were discharged the same day after a chest roentgenogram and a short stay in the outpatient clinic. Among them three patients (20%) experienced a minimal (<30%) pneumothorax that required no treatment, while five (33.3%) had a trunk compensatory sweating that spontaneously resolved on the long run. Patients undergoing GA were discharged after a mean stay of 1.38+/-0.6 days. Among these, eight (26.6%) had prolonged trunk compensatory sweating that did not persist longer than 3 months. At a follow-up of 7.16+/-2.97 months, QOL was significantly improved with no difference between groups. The overall rate of satisfaction was greater in the LA group (P<0.05). CONCLUSIONS: In our study, awake one stage bilateral thoracoscopic sympathectomy for palmar hyperhidrosis could be safely and effectively performed as an outpatient procedure in patients refusing GA. Postoperative quality of life was equal to that in patients undergone the same procedure under GA, while patient satisfaction was better and cost were significantly reduced.  相似文献   
46.
Stair motion in the presence of hip osteoarthritis (OA) has received less attention than level walking. Its more strenuous aspect may shed the light on different locomotor strategies when compared to walking. We, therefore, aimed to define stair motion features associated to hip OA and to evaluate whether these specific features would differ from level walking and better characterize the hip pathological condition. Principal component and linear discriminant analyses were, respectively, used as data reduction and classification techniques. Our study highlighted that most of stair motion features associated to hip OA were similar to the ones of walking. Stair descent presented with the lowest misclassification error rate, ranging from 12% to 19% (estimated by cross‐validation). But, features that may be considered as a mechanism to reduce demand on the hip abductors were found to be more important in the stair ascent condition. This was reflected by both, greater importance in the classification rule and variance compared with walking, that is, decreased hip internal rotation moment at mid‐stance (72.50% vs. 57.63%) and increased trunk lateroflexion toward affected side (56.43% vs. 29.37%). This study emphasized the importance of investigating stair motion in hip osteoarthritic population by highlighting specific locomotor strategies. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:187–196, 2016.  相似文献   
47.

Purpose

The aim of our study was to follow the evolution over time of multifocal intraductal papillary mucinous neoplasms (IPMN) of the pancreatic duct side branches by means of magnetic resonance imaging (MRI).

Materials and methods

A total of 155 patients with multifocal IPMN of the side branches were examined with MRI and MR cholangiopancreatography (MRI/MRCP). Inclusion criteria were patients with ≥2 dilated side branches involving any site of the parenchyma; presence of communication with the main pancreatic duct and previous investigations by MRI/MRCP within at least six months. Median follow-up was 25.8 months (range, 12–217). Patients with a follow-up period shorter than 12 months (n=33) and those with a diagnosis of multifocal IPMN of the side branches without any follow-up (n=14) were excluded from the study. The final study population thus comprised 108 patients. A double, quantitative and qualitative, analysis was carried out. The quantitative image analysis included: number of dilated side branches in the head-uncinate process and body-tail; maximum diameter of lesions in the head-uncinate process; maximum diameter in the body-tail; maximum diameter of the main pancreatic duct in the head and body-tail. The qualitative image analysis included: presence of malformations or anatomical variants of the pancreatic ductal system; site of the lesions (head-uncinate process, body-tail, ubiquitous, bridge morphology); presence of gravity-dependent intraluminal filling defects; presence of enhancing mural nodules.

Results

At diagnosis, the mean number of cystic lesions of the side branches was 7.09. The mean diameter of the cystic lesions was 13.7 mm. The mean diameter of the main pancreatic duct was 3.6 mm. At follow-up, the mean number of cystic lesions was 7.76. The mean diameter of the cystic lesions was 13.9 mm. The mean diameter of the main pancreatic duct was 3.7 mm. Intraluminal filling defects in the side branches were seen in 18/108 patients (16.6%); enhancing mural nodules were seen in 3/108 patients (2.7%).

Conclusions

Multifocal IPMN of the branch ducts shows a very slow growth and evolution over time. In our study, only 3/108 patients showed mural nodules which, however, did not require any surgical procedure, indicating that careful nonoperative management may be safe and effective in asymptomatic patients.  相似文献   
48.
The differential diagnosis of cystic neoformations in the pancreas is challenging. We report a case of a true solitary cyst of the pancreas in a 26-year old woman. Abdominal magnetic resonance imaging and computed tomography showed a unilocular neoformation in the head of the pancreas, without obstruction of Wirsung's duct. We excised the cyst and performed Roux-en-Y loop pancreaticojejunostomy, but the patient suffered recurrent acute pancreatitis from Wirsung's duct stenosis. Thus, a new Roux-en-Y loop pancreaticojejunostomy was successfully done 6 months later. Histologically, the cyst was lined by cuboidal epithelium, immunohistochemically positive to anti-carbohydrate antigen 19-9 antibodies. To our knowledge, only 11 cases of solitary true cyst of the pancreas in adults have been reported, so the characteristics of this unusual entity are not well known. We propose a scheme for the differential diagnosis of cystic neoformations of the pancreas, starting from the histopathological definition of a true solitary cyst.  相似文献   
49.

Background:

Superior mesenteric artery syndrome (SMAS) is a rare condition causing acute or chronic compression of the third part of the duodenum, due to a reduction in the aortomesenteric angle. Traditionally, an open duodenojejunostomy is recommended when conservative management fails. Laparoscopic duodenojejunostomy is a minimally invasive option that has been reported in up to 10 cases. We describe our operative technique in one case and review the literature on this condition.

Methods:

A previously well 66-year-old man presented with acute gastric dilatation. An abdominal computerized tomography (CT) scan and oral Gastrografin meal revealed a dilated stomach and proximal duodenum due to compression of the third part of the duodenum between the superior mesenteric artery (SMA) and aorta.

Results:

Esophagogastroduodenoscopy (EGD) ruled out intraluminal causes. A laparoscopic duodenojejunostomy was performed when conservative management failed. Postoperative recovery was quick and uneventful. Gastrografin administration on the fifth day showed no leak, with free flow of contrast into the jejunum. The patient resumed a normal diet and remained asymptomatic at 6-month follow-up.

Conclusion:

Laparoscopic duodenojejunostomy is feasible, safe, and effective. It gives the same results as open surgery with all the advantages of minimally invasive surgery.  相似文献   
50.
In this paper, radionuclidic impurities generated during the bombardment of [18 O]water in the routine production of 2-[18F]fluoro-2-deoxy-d-glucose ([18F]FDG) were studied. In order to assess such impurities and the efficacy of purification methods through the different steps of the synthesis, samples of the target filters, purification columns, [18 O]water recovered after the synthesis, and the final solution was collected and their activities measured and analyzed by means of a gamma-ray spectrometry system. The data demonstrated that purification methods adopted for the synthesis provide the [18F]FDG radionuclidically pure, as requested by the EU Pharmacopeia.  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