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   3707篇
  免费   213篇
  国内免费   31篇
耳鼻咽喉   60篇
儿科学   117篇
妇产科学   100篇
基础医学   684篇
口腔科学   86篇
临床医学   351篇
内科学   897篇
皮肤病学   64篇
神经病学   361篇
特种医学   95篇
外科学   300篇
综合类   12篇
一般理论   3篇
预防医学   181篇
眼科学   45篇
药学   325篇
中国医学   4篇
肿瘤学   266篇
  2023年   24篇
  2022年   85篇
  2021年   168篇
  2020年   66篇
  2019年   106篇
  2018年   106篇
  2017年   77篇
  2016年   111篇
  2015年   118篇
  2014年   155篇
  2013年   174篇
  2012年   295篇
  2011年   317篇
  2010年   155篇
  2009年   156篇
  2008年   249篇
  2007年   262篇
  2006年   237篇
  2005年   226篇
  2004年   171篇
  2003年   147篇
  2002年   159篇
  2001年   37篇
  2000年   29篇
  1999年   18篇
  1998年   27篇
  1997年   17篇
  1996年   26篇
  1995年   19篇
  1994年   19篇
  1993年   11篇
  1992年   18篇
  1991年   13篇
  1990年   14篇
  1989年   14篇
  1988年   11篇
  1987年   6篇
  1986年   12篇
  1985年   9篇
  1984年   12篇
  1983年   5篇
  1982年   9篇
  1981年   5篇
  1979年   9篇
  1978年   9篇
  1975年   5篇
  1974年   4篇
  1973年   5篇
  1969年   3篇
  1955年   3篇
排序方式: 共有3951条查询结果,搜索用时 15 毫秒
1.
2.
Sinus venosus atrial septal defect (SV‐ASD) usually coexists with partial anomalous pulmonary vein connection (PAPVC). It is a difficult diagnosis in transthoracic echocardiography (TTE) due to eccentric position of defects. We present a rare case of atypical anatomical variation in PAPVC, which was never described before. Two right pulmonary veins drained into superior vena cava, which overrode SV‐ASD and interatrial septum, a third pulmonary vein into the right atrium. Complete diagnosis could not be set after TTE, nor transesophageal echocardiography, whereas angio‐CT was finally conclusive. This diagnostic approach allowed the surgical planning.  相似文献   
3.

Background

Acute myocardial infarction (AMI) causes irreversible myocardial damage and release of inflammatory mediators, including cytokines, chemokines and miRNAs. We aimed to investigate changes in the levels of cytokines (IL-6, TNF-α and IL-10), miRNAs profiles (miR-146 and miR-155) and distribution of different monocyte subsets (CD14++CD16-, CD14++CD16+, CD14+CD16++) in the acute and post-healing phases of AMI.

Methods

In eighteen consecutive AMI patients (mean age 56.78?±?12.4 years, mean left ventricle ejection fraction – LVEF: 41.9?±?9.8%), treated invasively, monocyte subsets frequencies were evaluated (flow cytometry), cytokine concentrations were analyzed (ELISA) as well as plasma miRNAs were isolated twice – on admission and after 19.2?±?5.9 weeks of follow-up. Measurements were also performed among healthy volunteers.

Results

AMI patients presented significantly decreased frequencies of classical cells in comparison to healthy controls (median 71.22% [IQR: 64.4–79.04] vs. 84.35% [IQR: 81.2–86.7], p?=?0.001) and higher percent of both intermediate and non-classical cells, yet without statistical significance (median 6.54% [IQR: 5.14–16.64] vs. 5.87% [IQR: 4.48–8.6], p?=?0.37 and median 5.99% [IQR: 3.39–11.5] vs. 5.26% [IQR: 3.62–6.2], p?=?0.42, respectively). In AMI patients both, analyzed plasma miRNA concentrations were higher than in healthy subjects (miR-146: median 5.48 [IQR: 2.4–11.27] vs. 1.84 [IQR: 0.87–2.53], p?=?0.003; miR-155: median 25.35 [IQR: 8.17–43.15] vs. 8.4 [IQR: 0.08–16.9], p?=?0.027, respectively), and returned back to the values found in the control group in follow-up. miR-155/miR-146 ratio correlated with the frequencies of classical monocytes (r=0.6, p?=?0.01) and miR-155 correlated positively with the concentration of inflammatory cytokines ? IL-6 and TNF-α.

Conclusions

These results may suggest cooperation of both pro-inflammatory and anti-inflammatory signals in AMI in order to promote appropriate healing of the infarcted myocardium.  相似文献   
4.
5.
The potential cytoprotective actions of a novel nicotinic agent 2,4-dimethoxybenzilidene anabaseine (DMXB) were investigated in differentiated PC12 cells and transected rat septal cholinergic neurons in vivo. In NGF-differentiated PC12 cells, removal of both NGF and serum led to cell loss, a reduced % of cells expressing neurites, the release of lactate dehydrogenase, and a decrease in total cellular protein. Cell loss was apparent within 24 h, and remained constant between 4–8 days post-NGF removal. NGF alone (100 ng/ml), DMXB (10 μM), but not nicotine (10 μM), prevented these cell and neurite losses. DMXB-induced cytoprotection was blocked by 1 μM mecamylamine. DMXB (1 mg/kg, ip) injected twice but not once per day protected cholinesterase-staining septal neurons from retrograde degeneration following unilateral fimbrial transections. The twice per day DMXB injection-protocol also decreased cell roundness among cholinesterase-staining cells in the lesioned septal hemisphere compared to saline-injected animals. These studies suggest that DMXB may exert cytoprotective activity in NGF-sensitive neuronal populations. © 1994 Wiley-Liss, Inc.  相似文献   
6.
A quantified evaluation of planar cardiac perfusion scintigrams (the objective of the study), obtained using technetium-99m methoxyisobutylisonitrile (MIBI) was performed on the basis of an analysis of circumferential profile curves, representing the perfusion as seen in three typical projections. The analysis involved the curves obtained both at rest and after stress, and was based on a comparison of their shape (trend) with the normal trend (normative evaluation). The latter was obtained by means of an original method of iterative fitting of individual curves into the database. The base consisted of curves recorded in 53 patients (separately in males and females) with normal perfusion of the left ventricle (group I, the reference group). A group of 90 patients suspected of having coronary artery disease (group II) was subdivided into two subgroups on the basis of coronary arteriography: (a) those with and (b) those without critical stenosis of at least one artery. Profile curves characterising the LV perfusion were obtained at rest and after stress. Defects of perfusion were quantified by comparison of individual curves with the normal trends. By means of multivariate analysis it was demonstrated that vectors of mean values characterising the scintigraphically assessed defects of LV perfusion in the two subgroups of group II differed very significantly (P<10–5). Applying methods of discriminant analysis, a classification of patients from group II was performed into those with probable defects of perfusion and those free of such defects. The sensitivity, specificity and accuracy of diagnosis of coronary ischaemia, based on quantified planar99mTc-MIBI scintigraphy, reached 86%, 87% and 87%, respectively.  相似文献   
7.
Purpose of work was estimation of the results of treatment of pseudoarthrosis of the long bone with the method of decortication, with use of autogenic bone depends on kind of pseudoarthrosis and kind of osteosynthesis. In the years 1995-2005 56 patients were treated because of pseudoarthrosis of long bone in our Clinic. Pseudoarthrosis is classified according to Weber-Cech classification. In the methodology of clinical estimation and subjective estimation of the patient Stewart and Hundley and Anderson classification were used. Union was achieved in 51 cases. Time of bone union achievement was 5 months. The results of treatment are depends on morfology of pseudoartrosis and are independs of kind of osteosynthesis.  相似文献   
8.
9.
Extrinsic compression of the renal artery due to a fibromuscular band originating from the diaphragm was encountered in a 26-year-old patient who had systemic hypertension associated with stenosis and kinking of one of her renal arteries. After surgical decompression, the renal artery assumed a normal expansion with disappearance of hypertension. Six other cases of extrinsic compression of the renal artery have been found in the literature. Surgical treatment is mandatory in all cases because the mechanism that causes the lesion makes percutaneous transluminal angioplasty illusory.  相似文献   
10.
13C-NMR and the electron impact mass spectra of the β-carboline derivatives 1 – 18 were examined. The structure of the possible diastereomers is discussed. A quantitative relationship between the relative intensity of ions a in the mass spectra of 1 – 18 and the structure of substituents R was found.  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