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   8957篇
  免费   410篇
  国内免费   43篇
耳鼻咽喉   142篇
儿科学   212篇
妇产科学   182篇
基础医学   1382篇
口腔科学   208篇
临床医学   1045篇
内科学   1730篇
皮肤病学   250篇
神经病学   764篇
特种医学   475篇
外国民族医学   3篇
外科学   1243篇
综合类   72篇
一般理论   3篇
预防医学   395篇
眼科学   252篇
药学   661篇
中国医学   22篇
肿瘤学   369篇
  2022年   60篇
  2021年   99篇
  2020年   94篇
  2019年   113篇
  2018年   158篇
  2017年   124篇
  2016年   167篇
  2015年   203篇
  2014年   240篇
  2013年   312篇
  2012年   408篇
  2011年   425篇
  2010年   289篇
  2009年   300篇
  2008年   428篇
  2007年   474篇
  2006年   422篇
  2005年   406篇
  2004年   391篇
  2003年   406篇
  2002年   383篇
  2001年   156篇
  2000年   117篇
  1999年   122篇
  1998年   96篇
  1997年   106篇
  1996年   90篇
  1995年   83篇
  1994年   84篇
  1993年   75篇
  1992年   92篇
  1991年   84篇
  1990年   63篇
  1989年   67篇
  1988年   74篇
  1987年   75篇
  1986年   67篇
  1985年   49篇
  1984年   63篇
  1983年   69篇
  1982年   47篇
  1981年   44篇
  1940年   43篇
  1937年   39篇
  1933年   55篇
  1932年   45篇
  1931年   47篇
  1928年   40篇
  1927年   45篇
  1926年   56篇
排序方式: 共有9410条查询结果,搜索用时 33 毫秒
81.
82.
Ohne ZusammenfassungHierzu Taf. VI und VII.  相似文献   
83.
84.

Purpose

18F-Fluorocholine (FCH) and 11C-acetate (ACE) PET are widely used for detection of recurrent prostate cancer (PC). We present the first results of a comparative, prospective PET/CT study of both tracers evaluated in the same patients presenting with recurrence and low PSA to compare the diagnostic information provided by the two tracers.

Methods

The study group comprised 23 patients studied for a rising PSA level after radical prostatectomy (RP, 7 patients, PSA ≤3 ng/ml), curative radiotherapy (RT, 7 patients, PSA ≤5 ng/ml) or RP and salvage RT (9 patients, PSA ≤5 ng/ml). Both FCH and ACE PET/CT scans were performed in a random sequence a median of 4 days (range 0 to 11 days) apart. FCH PET/CT was started at injection (307?±?16 MBq) with a 10-min dynamic acquisition of the prostate bed, followed by a whole-body PET scan and late (45 min) imaging of the pelvis. ACE PET/CT was performed as a double whole-body PET scan starting 5 and 22 min after injection (994?±?72 MBq), and a late view (45 min) of the prostate bed. PET/CT scans were blindly reviewed by two independent pairs of two experienced nuclear medicine physicians, discordant subgroup results being discussed to reach a consensus for positive, negative end equivocal results.

Results

PET results were concordant in 88 out of 92 local, regional and distant findings (Cohen’s kappa 0.929). In particular, results were concordant in all patients concerning local status, bone metastases and distant findings. Lymph-node results were concordant in 19 patients and different in 4 patients. On a per-patient basis results were concordant in 22 of 23 patients (14 positive, 5 negative and 3 equivocal). In only one patient was ACE PET/CT positive for nodal metastases while FCH PET/CT was overall negative; interestingly, the ACE-positive and FCH-negative lymph nodes became positive in a second FCH PET/CT scan performed a few months later.

Conclusion

Overall, ACE and FCH PET/CT showed excellent concordance, on both a per-lesion and a per-patient basis, suggesting that both tracers perform equally for recurrent prostate cancer staging.  相似文献   
85.
86.
87.
88.
We studied clinical predictors of cranial computed tomography (CT) abnormalities in patients with acute or acutely worsened headache. Data were collected from chart review of 333 consecutive patients presenting to an emergency department and who were clinically selected for cranial CT. Patients with a positive neurologic examination were at 10.7 times greater risk for a positive CT than the rest of the sample (p<1.5 – 10−10). Using only neurologic examination to select patients for CT would have missed 30.3% of the positive scans. The amnesia, depressed sensorium, and hypertension variables had CT yields approximating 10% or greater even in the presence of a negative neurologic examination. Together with a positive neurologic examination, these variables detected 87.9% of the patients in this sample with positive scans; their absence had a negative predictive value of 98.0%. Of the four patients with positive scans who would have been missed using this strategy, one was discharged directly from the emergency department anyway and the other three developed positive neurologic examinations within 24 hours. One died of causes unrelated to the intracranial pathology. Positive neurologic examination, hypertension, history of amnesia, or a depressed sensorium provide reasonable initial guidelines to select for CT patients with an acute headache.  相似文献   
89.
Background Minimally invasive augmentation techniques of vertebral bodies have been advocated to treat osteoporotic vertebral body compression fractures (VBCFs). Kyphoplasty is designed to address both fracture-related pain as well as kyphotic deformity usually associated with fracture. Previous studies have indicated the potential of this technique for reduction of vertebral body height, but there has been little investigation into whether this has a lasting effect. The current study reports on our experience and the one-year results in 27 kyphoplasty procedures (24 patients) for osteoporotic VBCFs.Results All but one patient experienced pain relief following the procedure (on VAS 1–10)—with a lasting effect over the follow-up period in 25 cases. An average vertebral kyphosis reduction of 47.7% was achieved with no loss of reduction after one year. The potential for reduction was statistically related to the pre-operative amount of kyphosis, the level treated, and the age of the fracture, but not to the age of the patient. During follow-up, one fracture adjacent to a treated level was observed. Pain relief was not related to the amount of reduction.Conclusion Kyphoplasty is an effective treatment of VBCFs in terms of pain relief and durable reduction of deformity. Whether spinal realignment results in an improved long-term clinical outcome remains to be investigated.  相似文献   
90.
Bearing surface wear and periprosthetic osteolysis due to wear particles are among the most common reasons for joint replacement failure. A murine calvarial model of wear particle-induced osteolysis has been used to identify different biologic factors associated with this problem and to test nonsurgical methods of modulating the host response to particulate debris. This model has utilized titanium particles, however, in clinical practice the most common source of particulate debris is polyethylene particles from bearing surface wear. We now report a calvarial model of wear particle-induced osteolysis based on commercially available polyethylene particles. We found that compared to sham surgery osteoclast recruitment and bone resorption can be induced by introduction of the titanium particles or polyethylene particles. However, bone resorption was significantly higher with polyethylene particles compared to titanium particles (p=0.02). We consider the polyethylene based murine calvarial model of wear particle-induced osteolysis a reliable and clinically relevant tool to understand the host factors and potential pharmacologic interventions that can influence wear debris generated osteolysis. This model might serve as an extension of the well-established titanium based bone resorption model.  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