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   4603篇
  免费   187篇
  国内免费   38篇
耳鼻咽喉   130篇
儿科学   221篇
妇产科学   125篇
基础医学   317篇
口腔科学   160篇
临床医学   358篇
内科学   1123篇
皮肤病学   86篇
神经病学   310篇
特种医学   186篇
外科学   1021篇
综合类   100篇
一般理论   1篇
预防医学   206篇
眼科学   101篇
药学   187篇
中国医学   9篇
肿瘤学   187篇
  2023年   44篇
  2022年   63篇
  2021年   129篇
  2020年   73篇
  2019年   103篇
  2018年   127篇
  2017年   77篇
  2016年   147篇
  2015年   135篇
  2014年   162篇
  2013年   262篇
  2012年   347篇
  2011年   340篇
  2010年   183篇
  2009年   164篇
  2008年   343篇
  2007年   361篇
  2006年   373篇
  2005年   324篇
  2004年   300篇
  2003年   225篇
  2002年   198篇
  2001年   29篇
  2000年   29篇
  1999年   28篇
  1998年   6篇
  1997年   6篇
  1996年   10篇
  1995年   5篇
  1992年   17篇
  1991年   7篇
  1990年   11篇
  1989年   7篇
  1988年   15篇
  1987年   13篇
  1986年   16篇
  1985年   24篇
  1984年   12篇
  1983年   8篇
  1982年   9篇
  1981年   6篇
  1980年   6篇
  1979年   13篇
  1978年   8篇
  1976年   5篇
  1974年   8篇
  1972年   8篇
  1970年   4篇
  1969年   6篇
  1968年   6篇
排序方式: 共有4828条查询结果,搜索用时 31 毫秒
121.
Omer Toprak 《Renal failure》2013,35(3):387-388
Radiological procedures require the intravascular administration of iodinated contrast media, which are becoming a great source of an iatrogenic disease known as contrast-induced nephropathy. The development of contrast-induced nephropathy is associated with prolonged hospitalization, the potential need for renal replacement therapy, and increased mortality. Despite numerous clinical and experimental studies, several important issues regarding contrast-induced nephropathy remain controversial. One of the controversial points is its very definition: a universally accepted definition of contrast-induced nephropathy does not exist. This can be a major problem. Differing definitions of contrast-induced nephropathy and the clinical importance of these definitions were discussed in this letter.  相似文献   
122.
123.
PurposeExcision repair cross-complementation group 1 enzyme (ERCC1) plays a key role in the removal of platinum induced DNA adducts and cisplatin resistance. Prognostic role of ERCC1 expression in the neoadjuvant setting in bladder cancer has not been reported before. We evaluated the prognostic role of ERCC1 expression in bladder cancer receiving platinum-based neoadjuvant chemotherapy.Materials and methodsThirty-eight patients with muscle invasive bladder cancer who received neoadjuvant platinum-based chemotherapy were included. Clinical and histopathologic parameters along with immunohistochemical ERCC1 staining were examined and correlated with response rates and survival.ResultsPathologic complete response rates were similar between patients with low and high ERCC1 expression. Median disease-free survival (DFS) was 9.3 vs. 20.5 months (P = 0.186) and median overall survival (OS) was 9.3 vs. 26.7 months (P = 0.058) in patients with high ERCC1 expression compared with those with low expression, respectively. In multivariate Cox regression analysis: pathological complete response (pCR) after chemotherapy (hazard ratio (HR) 0.1, 95% CI 0.012–0.842, P = 0.034) and high ERCC1 expression (HR 3.7, 95% CI 1.2–11.2, P = 0.019) were significantly associated with DFS. Patient age (>60 vs. ≤60 years) (HR 3.4, 95% CI 1.2–9.4, P = 0.018), the presence of pCR (HR 0.11, 95% CI 0.014–0.981, P = 0.048) and high ERCC expression (HR 6.1, 95 CI 1.9–19.9, P = 0.002) were significantly associated with OS.ConclusionsOur results showed that high ERCC1 expression was independently associated with shorter disease-free and overall survival in patients with bladder cancer who received neoadjuvant platinum-based chemotherapy. ERCC1 may represent a potential predictive marker for platinum-based treatment in bladder cancer.  相似文献   
124.
125.
Toker H, Akp?nar A, Ayd?n H, Poyraz O. Influence of smoking on interleukin‐1beta level, oxidant status and antioxidant status in gingival crevicular fluid from chronic periodontitis patients before and after periodontal treatment. J Periodont Res 2012; 47: 572–577. © 2012 John Wiley & Sons A/S Background and Objective: The aim of this study was to evaluate the impact of smoking on the relationship between interleukin‐1 (IL‐1β) and oxidation in patients with periodontitis and response to nonsurgical periodontal therapy. Material and Methods: Data were obtained from 30 patients with generalized chronic periodontitis (15 smokers and 15 nonsmokers) and from 10 periodontally healthy controls. IL‐1β level, total oxidant status (TOS) and total antioxidant status (TAS) were recorded in gingival crevicular fluid. Probing depth, clinical attachment level, gingival and plaque indices and bleeding on probing were also measured. The gingival crevicular fluid and clinical parameters were recorded at baseline and 6 wk after periodontal treatment. Results: The study showed statistically significant improvement of clinical parameters in both smokers and nonsmokers after periodontal treatment. Moreover, the baseline IL‐1β levels were significantly higher in smokers compared with nonsmokers (p < 0.05). After periodontal treatment, the IL‐1β levels were significantly reduced in both smokers and nonsmokers (p < 0.05). There were no significant differences in TOS and TAS between periodontitis patients and healthy controls at baseline and 6 wk after periodontal treatment. The level of IL‐1β in gingival crevicular fluid was positively correlated with TOS in both smokers and nonsmokers. Conclusions: Periodontal treatment improved the clinical parameters in both smokers and nonsmokers. The results confirm that periodontal therapy has an effect on IL‐1β levels in gingival crevicular fluid, but not on TOS and TAS.  相似文献   
126.
22q11.2 deletion syndrome (22q11.2DS) is a common genetic risk factor for the development of schizophrenia. We investigated two neurophysiological endophenotypes of schizophrenia – P50 sensory gating and mismatch negativity in 22q11.2DS subject and evaluated their association with catechol O-methyltransferase (COMT) and proline dehydrogenase (PRODH) genetic variants. We also assessed the association of neurophysiological measures with schizophrenia-like symptomatology in 22q11.2DS. Fifty-nine subjects, 41 with 22q11.2DS and 18 typically developing controls, participated in the study. The participants with 22q11.2DS were genotyped for the COMT Val158Met (rs4680) and PRODH Gln19Pro (rs2008720) and Arg185Trp (rs4819756) polymorphisms. Following psychiatric evaluation, all the participants underwent neurophysiological recordings and executive function assessment. The 22q11.2DS group showed poorer sensory gating of the P50 response than the controls. Within the 22q11.2DS group, the COMT Met allele was associated with poorer sensory gating, while both the COMT Met allele and the PRODH Pro-Arg haplotype were associated with smaller mismatch negativity amplitudes. Smaller mismatch negativity amplitudes predicted greater impairment of executive functions and greater severity of schizophrenia-like negative symptoms in 22q11.2DS. The current study demonstrates that sensory gating impairments that are typical of schizophrenia are found in 22q11.2DS subjects. Our results further suggest that COMT and PRODH genetic variations contribute to sensory gating and mismatch negativity schizophrenia-like impairments in 22q11.2DS, possibly via dopaminergic/glutamatergic networks. The associations of mismatch negativity impairments with increased severity of schizophrenia-like negative symptoms and poorer executive functions performance in our 22q11.2DS sample suggest that mismatch negativity is a potential endophenotype for schizophrenia in 22q11.2DS.  相似文献   
127.

Background

The aim of this current report is to present an unusual case of a maxillary ameloblastoma mimicking an oroantral fistula.

Case report

A left subtotal maxillectomy via Weber–Ferguson-type incision was performed. The patient tolerated the procedure well, the postoperative course was uneventful, and the patient was discharged 3 days after surgery with a mild paraesthesia of the right infraorbital nerve distribution. The infraorbital nerve paraesthesia has resolved 5 months after resection. The patient has been followed-up for 3 years without recurrence.

Discussion

Ameloblastoma is a well-known pathology of the maxillofacial region. However, unusual manifestations of this tumor can represent a serious challenge for diagnosis.  相似文献   
128.
129.
130.
Introduction: Left ventricular hypertrophy (LVH) is one of the most common cardiac abnormalities in patients with end stage renal disease (ESRD). Hypertension, diabetes, increased body mass index, gender, age, anemia, and hyperparathyroidism have been described as risk factors for LVH in patients on dialysis. However, there may be other risk factors which have not been described yet. Recent studies show that renalase is associated with cardiovascular events. The aim of this study was to reveal the relation between renalase, LVH in patients under hemodialysis (HD) treatment.

Methods: The study included 50?HD patients and 35 healthy controls. Serum renalase levels and left ventricle mass index (LVMI) were measured in all participants and the relation between these variables was examined.

Findings: LVMI was positively correlated with dialysis vintage and C-reactive protein (CRP) (r?=?0.387, p?=?0.005 and r?=?0.597, p?r?=??0.324, p?=?0.022 and r?=??0.499, p?r?=?0.263, p?=?0.065). Serum renalase levels were significantly higher in HD patients (212?±?127?ng/mL) compared to controls (116?±?67?ng/mL) (p?r?=?0.677, p?r?=?0.625, p?Discussion: In our study, LVMI was correlated with dialysis vintage, residual diuresis, CRP, and hemoglobin. LVMI tends to correlate with renalase and this correlation may be significant in studies with more patient numbers. The main parameters affecting renalase levels are dialysis vintage and serum creatinine.  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