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   2761篇
  免费   82篇
  国内免费   18篇
耳鼻咽喉   12篇
儿科学   25篇
妇产科学   238篇
基础医学   289篇
口腔科学   18篇
临床医学   327篇
内科学   638篇
皮肤病学   11篇
神经病学   384篇
特种医学   75篇
外科学   420篇
综合类   7篇
预防医学   64篇
眼科学   7篇
药学   183篇
中国医学   2篇
肿瘤学   161篇
  2023年   8篇
  2022年   31篇
  2021年   65篇
  2020年   43篇
  2019年   49篇
  2018年   62篇
  2017年   41篇
  2016年   55篇
  2015年   68篇
  2014年   96篇
  2013年   125篇
  2012年   176篇
  2011年   195篇
  2010年   116篇
  2009年   99篇
  2008年   180篇
  2007年   153篇
  2006年   182篇
  2005年   154篇
  2004年   137篇
  2003年   186篇
  2002年   142篇
  2001年   44篇
  2000年   56篇
  1999年   36篇
  1998年   16篇
  1997年   21篇
  1996年   13篇
  1995年   18篇
  1994年   18篇
  1993年   14篇
  1992年   31篇
  1991年   26篇
  1990年   19篇
  1989年   20篇
  1988年   23篇
  1987年   15篇
  1986年   21篇
  1985年   17篇
  1984年   8篇
  1983年   11篇
  1982年   18篇
  1981年   6篇
  1980年   6篇
  1979年   6篇
  1978年   4篇
  1977年   4篇
  1976年   5篇
  1974年   4篇
  1971年   4篇
排序方式: 共有2861条查询结果,搜索用时 15 毫秒
91.
The purpose of this study was to investigate the potential contribution of genetic variants in the estrogen receptor beta gene to the aetiology of Parkinson's disease (PD). Several lines of evidence from human and animal studies suggest a protective role for estrogen in PD. Recently the estrogen receptor beta subtype was reported to be an important mediator of estrogen actions in the nigrostriatal dopamine system. Two single nucleotide polymorphisms at position 1730 and 1082 in the ER beta gene were genotyped, using pyrosequencing, in 260 patients with PD and 308 controls recruited from the Swedish population. Neither of the two estrogen receptor beta polymorphisms was associated with an increased risk for PD. However, the G allele of the A1730G polymorphism was more frequent in patients with an early age of onset than in patients with a late age of onset of PD (P = 0.006). Patients carrying the GG genotype had an odds ratio of 2.2 for having an early onset of PD compared to non-carriers. In conclusion, our results indicate that genetic variation in the estrogen receptor beta gene may influence the age of onset of PD.  相似文献   
92.
It has been recently shown that in vitro platelet aggregation is inhibited when platelet concentration in platelet-rich plasma (PRP) is “normalized” by the addition of platelet-poor plasma (PPP). In this study we tested the hypothesis that the large amount of PPP required to “normalize” PRP in patients with thrombocytosis may result in falsely defective platelet function. To this end, we evaluated platelet aggregation in PRP samples “normalized” with either PPP or buffer in 16 patients with high platelet counts induced by myeloproliferative disorders. Comparison with the results obtained in healthy subjects demonstrated that patients had reduced platelet responses to ADP or collagen in PRP/PPP samples, but normal responses in PRP/buffer. By contrast, the majority of patients had severely defective platelet response to epinephrine independently from the methodological approach. We suggest that the reduced in vitro platelet aggregation previously described in patients with myeloproliferative disorders and thrombocytosis partially derived from a laboratory artefact.  相似文献   
93.
This study analyses the frequency and the potential role of two polymorphisms, the +134del/insA, located in the gene encoding for Endothelin-1 (EDN1), and the His323His in the gene encoding for Endothelin receptor type A (EDNRA) in a cohort of 98 consecutive patients with pulmonary arterial hypertension from two different Cardiology Units (Mid-South of Italy), and in 100 healthy Caucasian subjects randomly recruited from the same area. Cardiac anatomy and function were analysed by non invasive diagnostic imaging techniques (Echocardiography standard m-mode, 2D, colour-Doppler) and by invasive studies (cardiac catheterization). Molecular screening of the region of interest was performed by automated sequencing. At univariate analysis, patients with the His323His TT genotype show a lower cardiac index (2 ± 0.6 vs. 2.3 ± 0.6; p = 0.05) and a higher indexed pulmonary vascular resistance (18.8 ± 9.6 vs. 14.2 ± 6.9; p = 0.01) at cardiac catheterization. A logistic multivariate model shows idiopathic disease (p = 0.01; OR = 3.8; CI = 1.3-11) and indexed pulmonary vascular resistances (p = 0.01; OR = 1.1; CI = 1-1.2) as independent predictors of TT genotype. Our findings may suggest a potential link between specific genotypes in the EDNRA gene and susceptibility for PAH.  相似文献   
94.
95.
The treatment of cirrhotic patients with spontaneous rupture of hepatocellular carcinoma (HCC) is controversial and largely dependent on general conditions of the patients and compensation of the underlying cirrhosis. We retrospectively reviewed clinical, imaging and surgical records of 24 consecutive cirrhotic patients (17 males, 7 females; age range 52–88 years) with hemoperitoneum from spontaneous rupture of HCC observed from June 2004 to January 2010 at our Institution. When indicated, patients were referred to surgery or trans-arterial embolization (TAE). Advanced decompensated patients were conservatively treated and clinically followed up. Spontaneous rupture of HCC was assessed by aspiration of bloody ascites at paracentesis in all cases. The presence of large blood-clots over HCC and liver surface at US and/or CT was considered a specific sign of ruptured HCC in 14 cases. In two out of four patients who underwent TAE active bleeding from tumor surface could be demonstrated. In 2 cases, the active hemorrhage from the HCC surface could be assessed by contrast-enhanced ultrasonography. Four out of 24 patients underwent surgery. Three out of four of these patients died within 2 weeks, 8 months, and 20 months after operation, respectively. The remaining patient is still alive at 52 months follow-up. Four patients underwent TAE and died at 1, 2, 6 and 10 months after treatment, because of recurrent peritoneal bleeding and/or liver failure. Sixteen patients with ruptured HCC in the advanced Child C cirrhosis were treated conservatively with blood derivative transfusion and with procoagulant drugs. All patients, but one died within 2–18 days. One patient survived the acute hemorrhage from ruptured HCC and died of liver failure after 3 months. We concluded that spontaneous rupture of HCC is usually a fatal event in patients with poor liver function, even after successful TAE. In compensated patients, timely surgical treatment can result in long term and even tumor-free survival of the patient.  相似文献   
96.
97.
98.
99.
Neuropathy and peripheral artery disease represent the main pathophysiological conditions underlying diabetic foot. Several studies showed that Lipoprotein(a)-Lp(a)-and homocysteine (Hcy) can be associated with diabetic complications, but their relationship with diabetic foot is unclear. Aim of this study was to investigate whether Lp(a) and Hcy were associated with diabetic foot ulcerations, classified according to the presence of peripheral artery disease (PAD) or neuropathy. From among consecutive type 2 diabetic attending at the Diabetic Foot Clinic 27 subjects with vascular diabetic foot (VDF), 43 with neuropathic diabetic foot (NDF) and 52 controls without foot ulceration, neuropathy, and PAD were enrolled. Both Lp(a) (26.1 ± 22.7 vs. 14.9 ± 19.5 mg/dl; P = 0.003) and Hcy levels (15.4 ± 5.7 vs. 12.2 ± 5.1 μmol/l; P = 0.022) were significantly greater in the VDF group than in controls. Lp(a) levels were significantly lower in the NDF group than in controls (6.9 ± 8.1 versus 14.9 ± 19.5 mg/dl; P = 0.009), while no difference in Hcy levels was found. Multiple logistic regression analysis showed that Hcy was associated with VDF (OR: 1.11; 95% CI: 1.07-14.1; P = 0.048). Lp(a) did not enter the model, but its P-value was very near to the significant level (OR: 1.09; 95% CI: 0.99-12.05; P = 0.059). Moreover, low Lp(a) levels were associated with NDF (OR: 0.84; 95% CI: 0.21-0.96; P = 0.039). Our study has shown for the first time that high Lp(a) and Hcy levels are associated with the development of VDF, while low Lp(a) levels appear to be associated with delayed wound healing in patients with neuropathic foot ulcerations.  相似文献   
100.
Recently, it has been demonstrated that high-resolution transthoracic echocardiography (HRTTE) is able to detect differences in the wall thickness of the left anterior descending coronary artery (LAD) between patients with coronary artery disease (CAD) and normal volunteers. The aim of this study was to further validate this technique. One hundred ten volunteers, 58 patients with angiographically proved CAD and 52 control subjects, underwent assessments of their LADs using HRTTE. Anterior and posterior wall thicknesses differed between subjects in the CAD group and controls (1.9 +/- 0.6 vs 1.2 +/- 0.3 mm, p <0.001, and 1.8 +/- 0.5 vs 1.2 +/- 0.3 mm, p <0.001, respectively). External LAD diameter was also greater in subjects in the CAD group compared with controls (5.2 +/- 1.9 vs 4.4 +/- 0.9 mm, respectively, p = 0.01). However, there was no difference in luminal diameter between subjects in the CAD group and the controls (1.9 +/- 0.9 vs 2.1 +/- 0.8 mm, respectively, p = 0.3). In conclusion, HRTTE demonstrated that LAD wall thicknesses and external diameters in patients with CAD were significantly larger than in normal volunteers. Luminal diameter, however, was maintained in the 2 groups, indicating that subjects in the CAD group had undergone positive remodeling at the site measured. This objectively visualized evidence of coronary atherosclerosis with HRTTE would likely be undetected during coronary angiography.  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