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   2783篇
  免费   127篇
  国内免费   15篇
耳鼻咽喉   33篇
儿科学   29篇
妇产科学   37篇
基础医学   229篇
口腔科学   44篇
临床医学   189篇
内科学   832篇
皮肤病学   107篇
神经病学   54篇
特种医学   101篇
外科学   567篇
综合类   10篇
一般理论   1篇
预防医学   119篇
眼科学   16篇
药学   133篇
中国医学   3篇
肿瘤学   421篇
  2023年   17篇
  2022年   22篇
  2021年   64篇
  2020年   26篇
  2019年   28篇
  2018年   53篇
  2017年   43篇
  2016年   57篇
  2015年   63篇
  2014年   56篇
  2013年   76篇
  2012年   131篇
  2011年   163篇
  2010年   80篇
  2009年   59篇
  2008年   103篇
  2007年   140篇
  2006年   139篇
  2005年   84篇
  2004年   92篇
  2003年   92篇
  2002年   74篇
  2001年   84篇
  2000年   126篇
  1999年   130篇
  1998年   62篇
  1997年   48篇
  1996年   50篇
  1995年   28篇
  1994年   31篇
  1993年   30篇
  1992年   76篇
  1991年   67篇
  1990年   60篇
  1989年   61篇
  1988年   50篇
  1987年   37篇
  1986年   30篇
  1985年   38篇
  1984年   22篇
  1983年   13篇
  1982年   13篇
  1979年   24篇
  1977年   22篇
  1975年   14篇
  1973年   15篇
  1972年   14篇
  1971年   13篇
  1969年   14篇
  1967年   13篇
排序方式: 共有2925条查询结果,搜索用时 31 毫秒
81.
82.
83.
Few studies have explored the topographic anatomy of the esophagus, posterior wall of the left atrium (LA), or fat pads using multidetector computed tomography (MDCT) to prevent the risk of esophageal injury during atrial fibrillation (AF) ablation. MDCT was performed in 110 consecutive patients with paroxysmal or persistent AF before the ablation procedure to understand the anatomic relationship of the esophagus. Two major types of esophagus routes were demonstrated. Leftward (type A) and rightward (type B) routes were found in 90 and 10% of the patients, respectively. A type A route had a larger mean size of the LA than type B. The fat pad was identifiable at the level of the inferior pulmonary vein in 91% of the patients without any predominance of either type. The thickness of the fat pad was thinner in the patients with a dilated LA (>42?mm) than in those with a normal LA size (??42?mm) (p?=?0.01). The results demonstrated that the majority of cases had a leftward route of the esophagus. There was a close association between the LA dilatation and fat pad thinning. With a dilated LA, the esophagus may become easily susceptible to direct thermal injury during AF ablation. Visualization of the anatomic relationship may contribute to the prevention of the potential risk of an esophageal injury.  相似文献   
84.

Background

Klotho is a single-pass transmembrane protein, which appears to be implicated in aging. The purpose of the present study was to characterize the relationship between the soluble Klotho level and renal function in patients with various degrees of chronic kidney disease (CKD).

Methods

The levels of soluble Klotho in the serum and urine obtained from one hundred thirty-one CKD patients were determined by a sandwich enzyme-linked immunosorbent assay system.

Results

The amount of urinary excreted Klotho during the 24 hr period ranged from 1.6 to 5178 ng/day (median 427 ng/day; interquartile range [IR] 56.8-1293.1), and the serum Klotho concentration ranged from 163.9 to 2123.7 pg/ml (median 759.7 pg/ml; IR 579.5-1069.1). The estimated glomerular filtration rate (eGFR) was significantly correlated with the log-transformed values of the amount of 24 hr urinary excreted Klotho (r?=?0.407, p?<?0.01) and the serum Klotho levels (r?=?0.232, p?<?0.01). However, a stepwise multiple regression analysis identified eGFR to be a variable independently associated only with the log-transformed value of the amount of 24-hr urinary excreted Klotho but not with the log-transformed serum Klotho concentration. Despite the strong correlation between random urine protein-to-creatinine ratio and the 24 hr urinary protein excretion (r?=?0.834, p?<?0.01), a moderate linear association was observed between the log-transformed value of the amount of 24 hr urinary excreted Klotho and that of the urinary Klotho-to-creatinine ratio (Klotho/Cr) in random urine specimens (r?=?0.726, p?<?0.01).

Conclusions

The amount of urinary Klotho, rather than the serum Klotho levels, should be linked to the magnitude of the functioning nephrons in CKD patients. The use of random urine Klotho/Cr as a surrogate for the amount of 24-hr urinary excreted Klotho needs to be evaluated more carefully.
  相似文献   
85.
86.

Background

Dysplastic squamous epithelium is a precancerous lesion for squamous cell carcinoma. It is often present in the esophagus and head and neck region, and can be visualized as a Lugol-voiding lesion (LVL) by iodine chromoendoscopy. However, effective treatment for such dysplastic epithelia has not yet been developed.

Methods

Between March 2008 and July 2011, 40 consecutive patients with advanced esophageal squamous cell carcinoma were treated by two cycles of neoadjuvant chemotherapy (NAC) (5-fluorouracil, 800?mg/m2, d 1?C5; cisplatin, 80?mg/m2, d 1: q 21?days) at Kyoto University Hospital, and received iodine chromoendoscopy both before and after NAC. Iodine chromoendoscopy findings were divided into 4 groups: group?A, absence of LVLs; group?B, several (??10/one endoscopic view) small (??5?mm) LVLs; group?C, many (??10/one endoscopic view) small (??5?mm) LVLs; group?D, numerous irregular-shaped multiform LVLs. Group?C and D are defined as multiple LVLs. Endoscopic changes of LVLs before and after NAC were investigated retrospectively.

Results

Before NAC, 6, 12, 9, and 13 cases were classified in group?A, B, C, and D, respectively. All cases in group?A before NAC remained in group?A after NAC. Multiple LVLs (group?C and D) were significantly improved in 17 of 22 patients (77.3?%), while several small LVLs (group?B) were improved in only 4 of 12 cases (33.3?%) (p?=?0.025 by Fisher??s exact test).

Conclusions

Multiple dysplastic lesions tended to improve by chemotherapy. In contrast, there was little change in the mucosa with fewer dysplastic lesions after chemotherapy. These data show that chemotherapy has the potential to eliminate precancerous lesions.  相似文献   
87.
Triamcinolone acetonide (TA) injections are widely used to treat enthesopathy, but they may induce adverse effects such as tendon impairment and rupture. Platelet‐rich plasma (PRP) is a blood fraction containing high platelet concentrations and various growth factors that play a role in tissue repair processes. The purpose of this study is to investigate whether TA has deleterious effects on human rotator cuff‐derived cells, and if PRP can protect these cells from the effects of TA. Human rotator cuff‐derived cells were cultured with and without TA and PRP, and the culture without any additive served as the control. Cell morphology was assessed at days 7 and 21. Cell viability was evaluated at days 1, 7, 14, and 21 by a water‐soluble tetrazolium salt assay. Induction of apoptosis was measured by immunofluorescence staining and flow cytometry at day 7. Induction of cleaved caspase‐3 was measured by immunofluorescence staining at day 7. The cells cultured with TA had a flattened and polygonal shape at day 7. The cells cultured with both TA and PRP were similar in appearance to control cells. Exposure to TA also significantly decreased cell viability, but cell viability did not decrease when PRP was added along with TA. The number of apoptotic cells increased with TA exposure, while addition of PRP prevented cell apoptosis. In conclusion, the deleterious effect of TA was prevented by PRP, which can be used as a protective agent for patients receiving local TA injections. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 976–982, 2013  相似文献   
88.
89.
90.

Background

The significance of perineural invasion in extrahepatic cholangiocarcinoma has not been fully elucidated. This study aims to determine the prognostic impact of and optimal treatment strategy for perineural invasion in patients with extrahepatic cholangiocarcinoma.

Methods

Medical records of 133 patients with extrahepatic cholangiocarcinoma who underwent curative resection were reviewed retrospectively. Ninety-eight patients had perineural invasion and 35 patients did not. Univariate and multivariate survival analyses were performed to clarify the prognostic impact of and optimal treatment strategy for perineural invasion.

Results

Only tumor differentiation (P?=?0.024) was independently associated with perineural invasion in the multivariate logistic regression model. Multivariate survival analysis revealed that perineural invasion (P?=?0.002), resection margin status (P?=?0.016), and International Union Against Cancer (UICC) pT factor (P?=?0.015) were independent prognostic factors of overall survival. Overall 5-year survival rates for patients with and without perineural invasion were 28 and 74 %, respectively. Among 98 patients with perineural invasion, the use of adjuvant chemotherapy (P?=?0.003), lymph node status (P?=?0.015), resection margin status (P?=?0.008), and UICC pT factor (P?=?0.016) were independently associated with overall survival by multivariate analysis. Overall 5-year survival rates for patients with perineural invasion who did and did not receive adjuvant chemotherapy were 33 and 21 %, respectively (P?=?0.023).

Conclusions

Perineural invasion is a potent prognostic factor in extrahepatic cholangiocarcinoma. Adjuvant chemotherapy may improve the overall survival of patients with perineural invasion.  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