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   18051篇
  免费   999篇
  国内免费   107篇
耳鼻咽喉   119篇
儿科学   552篇
妇产科学   364篇
基础医学   2451篇
口腔科学   324篇
临床医学   1448篇
内科学   4426篇
皮肤病学   350篇
神经病学   1950篇
特种医学   860篇
外科学   2085篇
综合类   37篇
一般理论   2篇
预防医学   864篇
眼科学   168篇
药学   1286篇
中国医学   41篇
肿瘤学   1830篇
  2023年   151篇
  2022年   332篇
  2021年   542篇
  2020年   342篇
  2019年   449篇
  2018年   473篇
  2017年   352篇
  2016年   425篇
  2015年   450篇
  2014年   610篇
  2013年   803篇
  2012年   1140篇
  2011年   1204篇
  2010年   635篇
  2009年   588篇
  2008年   988篇
  2007年   1004篇
  2006年   898篇
  2005年   809篇
  2004年   761篇
  2003年   684篇
  2002年   646篇
  2001年   423篇
  2000年   421篇
  1999年   432篇
  1998年   167篇
  1997年   117篇
  1996年   120篇
  1995年   95篇
  1994年   92篇
  1993年   86篇
  1992年   278篇
  1991年   259篇
  1990年   265篇
  1989年   249篇
  1988年   188篇
  1987年   164篇
  1986年   183篇
  1985年   207篇
  1984年   120篇
  1983年   100篇
  1982年   67篇
  1981年   48篇
  1979年   108篇
  1977年   56篇
  1976年   53篇
  1975年   53篇
  1974年   47篇
  1973年   56篇
  1971年   47篇
排序方式: 共有10000条查询结果,搜索用时 21 毫秒
21.
A case of partially reversible chronic renal failure due tolong-term NSAID use is discussed. An analysis of this and similarcases recently reported indicates many similarities betweenchronic NSAID nephropathy and analgesic nephropathy.  相似文献   
22.
A case of Cushing's syndrome in a 24-yr-old homosexual with an AIDS-related complex is reported. In this patient certain symptoms common to both diseases, i.e. weakness, myalgia and muscle atrophy were accentuated, whereas other symptoms pathognomic of the human immunodeficiency virus (HIV) infection, i.e. lymphoadenopathies and weight loss, were less pronounced by the high levels of circulating adrenal steroids. Ketoconazole was administered po in order to block adrenal steroidogenesis, the drug caused a remarkable fall of cortisol serum concentrations, but was unable to modify significantly the immunological pattern of the patient. Our data suggest that changes of serum adrenal steroid levels have little effect on the immune network of patients with AIDS.  相似文献   
23.
The grumose degeneration observed in the dentate nuclei of 7 cases of progressive supranuclear palsy (PSP) was studied with a panel of antibodies which included 2 neurofilaments, Tau and ubiquitin. Dentate nucleus neurons were negative with all antibodies except ubiquitin which showed a slightly positive homogeneous pattern of staining. The amorphous material surrounding swollen or normal neurons was strongly positive for neurofilament and subunits and numerous torpedoes were observed in the granular layer of the cerebellar cortex. Our results confirm that grumose degeneration consists in degeneration of terminal axons of Purkinje cells in the dentate nucleus. The positivity of dentate nucleus neurons for ubiquitin may support the concept of synaptic dysfunction between Purkinje cells and dentate nucleus neurons.  相似文献   
24.
Murine thymus has been demonstrated to contain both cholinergic receptors and acetylcholinesterase activity. In the present study we have investigated the presence of the enzyme choline acetyltransferase in this organ, which is responsible for the synthesis of acetylcholine. Results reported here demonstrate that (1) an appreciable amount of the enzyme is already present in the thymus on the day of birth; (2) its expression is developmentally regulated; and (3) thymic atrophy, induced in young (2-week-old) and adult (6-week-old) mice by i.p. injection of hydrocortisone for 2 days, is accompanied by significant reduction of choline acetyltransferase activity only in young mice. Altogether these results demonstrate the presence in the murine thymus of functionally relevant markers of the cholinergic system that might interface the interactions between the nervous and immune systems.  相似文献   
25.
1. Airways derived from different levels of the lung exhibit a difference in the reactivity and sensitivity to agonists. We have evaluated the effect of acetylcholine and cholinergic selective (pirenzepine, gallamine and 4-dipherylacetoxymethyl piperidine [4-DAMP]) and non-selective (atropine) antagonists on bovine proximal and distal smooth muscle preparations. 2. The distal preparations are more sensitive to acetylcholine than proximal bronchi. The relaxant effect of three selective antagonists on the distal and proximal tissues was the same when the results for each drug were compared. 3. Atropine and 4-DAMP were more potent than pirenzepine and gallamine in relaxing both proximal and distal bovine smooth muscle preparations. 4. These data suggest that the muscarinic sites on the smooth muscle of bovine airways are of the M3 subtype.  相似文献   
26.
BACKGROUND: Severe asthma is characterized by elevated levels of pro-inflammatory cytokines and neutrophilic inflammation in the airways. Blood cytokines, markers of 'systemic' inflammation, may be a feature of amplified inflammation in severe asthma. OBJECTIVE: To detect differences in IL-8, TNF-alpha, IL-16 and IL-13 levels in the serum(s) of stable severe and mild-moderate asthmatics related to blood leucocytes proportion, airway calibre and exhaled nitric oxide (NO) levels. METHODS: We assessed cytokine serum levels by ELISA and blood leucocyte counts by an alkaline peroxidase method in 20 healthy controls, 22 mild-moderate [forced expiratory volume in 1 s (FEV1)(%pred): 89+/-3] and 14 severe asthmatics [FEV1(%pred): 49+/-2]. RESULTS: IL-8 and TNF-alpha levels were higher in severe asthmatics than in mild-moderate asthmatics or in controls (P<0.05). No differences in IL-16 and IL-13 levels were detected. Severe asthmatics showed higher circulating neutrophil and eosinophil number than controls (P<0.05). In severe asthmatics, exhaled NO levels were superior than in controls (P<0.05), but inferior than in mild-moderate asthmatics (P<0.05). We found positive correlation between TNF-alpha levels and exhaled NO (r=0.67; P=0.01) or circulating neutrophil counts (r=0.57; P=0.03) in severe asthmatics. CONCLUSION: sTNF-alpha and sIL-8 are markers of 'systemic' inflammation in severe asthmatics, in conjunction with augmented circulating neutrophils, suggesting the involvement of neutrophil-derived cytokine pattern in severe asthma.  相似文献   
27.
AIM: To report on the histologic evaluation of renal tumors after intraoperative radiofrequency ablation (RFA) performed immediately before surgical nephrectomy. MATERIALS AND METHODS: Ten patients with renal tumors were studied. All tumors were confirmed to be renal cell carcinoma before radio frequency ablation treatment. All specimens were stained with hematoxylin and eosin and nicotinamide adenine dinucleotide (NADH). RESULTS: Mean tumor size was 29 mm (range 14 to 48 mm). Of the 10 tumors 5 were completely devitalized with a treatment margin ranged from 1 to 20mm. One tumor needed two treatment sessions. No complication related to radiofrequency treatment was recorded. CONCLUSIONS: Our data indicate that RFA can completely destroy renal tumors. However, in our study, complete tumor cell death was obtained only in 50% of cases. More studies are needed to ensure that is technique is an effective and reproducible treatment.  相似文献   
28.
Agenesis of common carotid artery is rare and no report of stenting procedures (carotid artery stenting) for associated stenosis of the internal carotid have been published. We report a case of internal carotid stenosis associated with this anomaly. A 73-year-old male with left internal carotid artery originating from the arch, with significant stenosis, was referred to us. Wallstent was deployed with success. Carotid artery stenting should be reserved to uncomplicated arch anatomy and plaques with low fragmentation risk.  相似文献   
29.
OBJECTIVE: Patients with non-small cell lung cancer (NSCLC) with metastases to ipsilateral mediastinal lymph nodes (N2) are an heterogeneous group of patients as regard to prognosis and treatment. Indication and timing of surgery remain controversial. The present study investigates the prognostic factors, in order to identify homogenous subgroups of patients. METHODS: Histologically proven N2-NSCLC patients, who underwent a complete surgical resection were retrospectively reviewed. Clinical and pathological features were reported and analyzed, and survival study was performed. RESULTS: One hundred eighty-three patients were analyzed. Overall 1.3 and 5 years survival rates were, respectively, 70, 35 and 20%, with a median survival time of 24 months. Univariate analysis showed a significant better prognosis for: incidental N2 respect to clinical N2 (5-years 35.4 vs 17.4%); single level lymph node involvement respect to multiple levels (5-years 23.8 vs 14.7%); metastases to superior mediastinal or aortic nodes respect to lower mediastinal nodes (5-years 32 and 24.3 vs 16.3%); right upper lobe tumors with superior mediastinal nodes and left upper lobe tumors with aortic nodes respect to lower lobes tumors with lower mediastinal nodes (5-years 31.8 and 26.9 vs 15.7%). Skip metastases had not a significant survival advantage respect to continuous lymphatic spread. N2 clinical status, the number of levels involved and the two specific patterns of lymphatic spread resulted significant prognostic factors at multivariate analysis. CONCLUSIONS: Clinical N2 status, number of lymph nodes levels involved and specific patterns of lymphatic spread identify homogenous subgroups of patients that can be proposed for different therapeutic strategies.  相似文献   
30.
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