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   5516篇
  免费   298篇
  国内免费   36篇
耳鼻咽喉   142篇
儿科学   136篇
妇产科学   45篇
基础医学   716篇
口腔科学   137篇
临床医学   320篇
内科学   1424篇
皮肤病学   81篇
神经病学   633篇
特种医学   142篇
外科学   912篇
综合类   22篇
预防医学   141篇
眼科学   71篇
药学   409篇
中国医学   10篇
肿瘤学   509篇
  2023年   30篇
  2022年   72篇
  2021年   135篇
  2020年   65篇
  2019年   94篇
  2018年   110篇
  2017年   88篇
  2016年   89篇
  2015年   100篇
  2014年   140篇
  2013年   157篇
  2012年   270篇
  2011年   324篇
  2010年   176篇
  2009年   144篇
  2008年   249篇
  2007年   291篇
  2006年   289篇
  2005年   254篇
  2004年   293篇
  2003年   252篇
  2002年   234篇
  2001年   148篇
  2000年   184篇
  1999年   177篇
  1998年   76篇
  1997年   55篇
  1996年   63篇
  1995年   45篇
  1994年   48篇
  1993年   58篇
  1992年   117篇
  1991年   87篇
  1990年   104篇
  1989年   121篇
  1988年   95篇
  1987年   81篇
  1986年   78篇
  1985年   65篇
  1984年   49篇
  1983年   35篇
  1982年   24篇
  1981年   16篇
  1980年   23篇
  1979年   38篇
  1978年   20篇
  1977年   28篇
  1975年   17篇
  1968年   17篇
  1966年   16篇
排序方式: 共有5850条查询结果,搜索用时 15 毫秒
991.
992.
993.

Background

Acute coronary syndrome (ACS) may occur during any human activity, including driving. The objectives of this study were to report the frequency of ACS occurring while driving, clarify patient characteristics, and analyze the behavioral patterns of drivers who sustained ACS.

Methods

A single-center, retrospective observational study was conducted using prospectively acquired data. Among 1605 ACS patients admitted between January 2011 and December 2016, 65 (60 men/5 women) patients who sustained ACS while driving were identified. Clinical variables were compared between these 65 patients and 1540 patients who sustained ACS while performing other activities. Furthermore, multivariable regression analysis was performed to identify variables associated with ACS.

Results

The frequency of ACS occurring while driving was 4.0% (65/1605). Compared with patients who sustained ACS while performing other activities, those who sustained ACS while driving were significantly younger (66.2?±?13.0 vs. 57.5?±?12.2 years, p?<?0.001) and more likely to smoke (34.2 vs. 60.0%, p?<?0.001). Multivariable regression analysis showed that age (OR 0.961; 95% CI 0.940–0.982) and current smoking (OR 1.978; 95% CI 1.145–3.417) were associated with ACS. While 55 drivers (85%) who remained conscious after ACS could seek medical attention without causing accidents, the other 10 (15%) who sustained cardiac arrest caused accidents.

Conclusions

The association between current smoking and ACS occurring while driving suggests that smoking cessation is advised for smokers who drive from the standpoint of driving safety. We expect that prospective studies be conducted to verify our findings and identify individuals at risk for ACS while driving.
  相似文献   
994.
Graefe's Archive for Clinical and Experimental Ophthalmology - To disclose histological advantages of intrascleral fixation of intraocular lens haptics, in comparison with scleral suture...  相似文献   
995.

Study Design

Multicenter retrospective study.

Background

Postoperative surgical site infection is one of the most serious complications following spine surgery. Previous studies do not appear to have investigated pyogenic discitis following lumbar laminectomy without discectomy. This study aimed to identify risk factors for postoperative pyogenic discitis following lumbar decompression surgery.

Methods

We examined data from 2721 patients undergoing lumbar laminectomy without discectomy in five hospitals from April 2007 to March 2012. Patients who developed postoperative discitis following laminectomy (Group D) and a 4:1 matched cohort (Group C) were included. Fisher's exact test was used to determine risk factors, with values of p < 0.05 considered statistically significant.

Results

The cumulative incidence of postoperative discitis was 0.29% (8/2721 patients). All patients in Group D were male, with a mean age of 71.6 ± 7.2 years. Postoperative discitis was at L1/2 in 1 patient, at L3/4 in 3 patients, and at L4/5 in 4 patients. Except for 1 patient with discitis at L1/2, every patient developed discitis at the level of decompression. The associated pathogens were methicillin-resistant Staphylococcus aureus (n = 3, 37.5%), methicillin-susceptible Staphylococcus epidermidis (n = 1, 12.5%), methicillin-sensitive S. aureus (n = 1, 12.5%), and unknown (n = 3, 37.5%). In the analysis of risk factors for postoperative discitis, Group D showed a significantly lower ratio of patients who underwent surgery in the winter and a significantly higher ratio of patients who had Modic type 1 in the lumbar vertebrae compared to Group C.

Conclusions

Although further prospective studies, in which other preoperative modalities are used for the evaluation, is needed, our data suggest the presence of Modic type 1 as a risk factor for discitis following laminectomy. Latent pyogenic discitis should be carefully ruled out in patients with Modic type 1. If lumbar laminectomy is performed for such patients, more careful observation is necessary to prevent the development of postoperative discitis.  相似文献   
996.
997.
998.
FBXW7 is a ubiquitin ligase that mediates ubiquitylation of oncoproteins, such as c‐Myc, cyclin E, Notch and c‐Jun. FBXW7 is a known tumor‐suppressor gene, and mutations in FBXW7 have been reported in various human malignancies. In this study, we examined the sequences of the FBXW7 and p53 genes in 57 ovarian cancer clinical samples. Interestingly, we found no FBXW7 mutations associated with amino acid changes. We also investigated FBXW7 expression levels in 126 epithelial ovarian tumors. FBXW7 expression was negatively correlated with the malignant potential of ovarian tumors. That is to say, FBXW7 expression levels in ovarian cancer samples were significantly lower than those in borderline and benign tumors (P < 0.01). FBXW7 expression levels in serous carcinoma samples were the lowest among four major histological subtypes. In addition, p53‐mutated ovarian cancer samples showed significantly lower levels of FBXW7 expression compared with p53 wild‐type cancer samples (P < 0.001). DNA methylation arrays and bisulfite PCR sequencing experiments revealed that 5′‐upstream regions of FBXW7 gene in p53‐mutated samples were significantly higher methylated compared with those in p53 wild‐type samples (P < 0.01). This data indicates that p53 mutations might suppress FBXW7 expression through DNA hypermethylation of FBXW7 5′‐upstream regions. Thus, FBXW7 expression was downregulated in ovarian cancers, and was associated with p53 mutations and the DNA methylation status of the 5′‐upstream regions of FBXW7.  相似文献   
999.
Transforming growth factor‐β activated kinase 1 (TAK1) has been shown to play a crucial role in cell death, differentiation, and inflammation. Here, we live‐imaged robust TAK1 activation in Lewis lung carcinoma 3LL cells implanted into the s.c. tissue of syngeneic C57BL/6 mice and treated with polyinosinic:polycytidylic acid (PolyI:C). First, we developed and characterized a Förster resonance energy transfer‐based biosensor for TAK1 activity. The TAK1 biosensor, named Eevee‐TAK1, responded to stress‐inducing reagents such as anisomycin, tumor necrosis factor‐α, and interleukin1‐β. The anisomycin‐induced increase in Förster resonance energy transfer was abolished by the TAK1 inhibitor (5z)‐7‐oxozeaenol. Activity of TAK1 in 3LL cells was markedly increased by PolyI:C in the presence of macrophages. 3LL cells expressing Eevee‐TAK1 were implanted into mice and observed through imaging window by two‐photon excitation microscopy. During the growth of tumor, the 3LL cells at the periphery of the tumor showed higher TAK1 activity than the 3LL cells located at the center of the tumor, suggesting that cells at the periphery of the tumor mass were under stronger stress. Injection of PolyI:C, which is known to induce regression of the implanted tumors, induced marked and homogenous TAK1 activation within the tumor tissues. The effect of PolyI:C faded within 4 days. These observations suggest that Eevee‐TAK1 is a versatile tool to monitor cellular stress in cancer tissues.  相似文献   
1000.
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