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   2898篇
  免费   170篇
  国内免费   19篇
耳鼻咽喉   61篇
儿科学   53篇
妇产科学   133篇
基础医学   253篇
口腔科学   103篇
临床医学   220篇
内科学   801篇
皮肤病学   58篇
神经病学   303篇
特种医学   89篇
外科学   414篇
综合类   8篇
预防医学   105篇
眼科学   100篇
药学   160篇
中国医学   1篇
肿瘤学   225篇
  2024年   5篇
  2023年   45篇
  2022年   83篇
  2021年   148篇
  2020年   79篇
  2019年   107篇
  2018年   125篇
  2017年   88篇
  2016年   90篇
  2015年   94篇
  2014年   131篇
  2013年   163篇
  2012年   227篇
  2011年   234篇
  2010年   117篇
  2009年   123篇
  2008年   167篇
  2007年   143篇
  2006年   155篇
  2005年   133篇
  2004年   124篇
  2003年   110篇
  2002年   109篇
  2001年   26篇
  2000年   26篇
  1999年   25篇
  1998年   9篇
  1997年   15篇
  1996年   16篇
  1995年   16篇
  1994年   16篇
  1993年   12篇
  1992年   18篇
  1991年   7篇
  1990年   10篇
  1989年   6篇
  1988年   10篇
  1987年   5篇
  1986年   7篇
  1985年   12篇
  1984年   10篇
  1983年   6篇
  1982年   5篇
  1981年   3篇
  1980年   3篇
  1976年   4篇
  1974年   3篇
  1969年   2篇
  1968年   3篇
  1966年   2篇
排序方式: 共有3087条查询结果,搜索用时 15 毫秒
1.
Introduction: Recently, a new minimally invasive single bundle technique for anatomic ACL reconstruction has been described, called the ‘All-Inside graft-link technique’. One of the advantages of this procedure is the reduced morbidity at the donor site as the graft choice is the quadrupled semitendinosus, thus sparing the gracilis tendon. The aim of this study was to evaluate isokinetic flexion strength recovery in patients who underwent a gracilis sparing technique compared to those with a full-tibial tunnel technique using a doubled gracilis and semitendinosus tendons (DGST) graft.

Methods: Patients were divided into two groups: Group A (22 patients) who underwent ACL reconstruction performed with an All-Inside graft-link technique; Group B (22 patients) who underwent ACL reconstruction with an Out-In technique and DGST graft. At a mean follow-up of 13 months, quadriceps and hamstring isokinetic peak torque deficits were recorded.

Results: In group A, the mean side to side peak torque flexion difference between the operated and non-operated limbs was ?3% and the mean torque at 30° was ?7.5% at high angular velocity (180°/sec); the mean peak flexion torque was 7.2% and the mean torque at 30° was 3.1% at low angular velocity (60°/sec).

In group B, the mean side to side peak flexion torque was ?3.5% and the mean torque at 30° was ?7.6% at high angular velocity (180°/sec); the mean peak flexion torque was ?7.2% and the mean torque at 30° was ?11% at low angular velocity (60°/sec).

A statistically significant difference was found between the two groups at lower angular velocity both for the mean peak flexion torque and the mean torque at 30° (= 0.009), with better results in the study group.

Discussion/conclusion: Gracilis sparing technique is a minimally invasive technique for ACL reconstruction and yielded a significantly better flexion strength recovery at lower angular velocity compared to a full tibial tunnel technique with DGST for ACL reconstruction.  相似文献   

2.
3.
Thiazolidinediones (TZDs), agonists of the nuclear receptor peroxisome proliferator-activated receptor-γ, induce the expression of many genes, including several enzymes and transporters involved in glucose and lipid metabolism. Although the efficacy of TZDs on blood glucose control in type 2 diabetes is not questionable, their cardiovascular effects have been debated, with beneficial or harmful actions suggested by different authors. This article reviews the available clinical evidence on the cardiovascular effects of TZDs, discussing possible mechanisms underlying the observed effects and suggesting some directions for future research.  相似文献   
4.
Patient monitoring at the bedside is an inherently parallel job, best handled by multiple individual tasks running concurrently. Cost and diffusion considerations strongly favor the use of PC's at the bedside, but their most widespread operating system, DOS, is not built for multitasking. Hence, a software platform in C language has been prepared, allowing the intermediate programmer to easily write independent modules which will then run simultaneously without conflicts.Such a platform aims at allowing effortless sharing of data among concurrently running processes, while providing strong insulation between tasks, enough to allow multiple copies of any one task to run simultaneously unknown to each other. A cooperative, memory sharing multitasking paradigm has been chosen, which offers fine granularity of timeslicing and low execution overhead at the price of some loss in generality of design.Speed, data exchange capability and number of stackable windows are greater than with commercial packages like Windows or LabWinows. Dynamical reprioritization of tasks is built in, allowing the computerized monitor to focus its attention and resources on urgent tasks.  相似文献   
5.
A marked increase has recently been noted in the incidence of lymphoma in patients with AIDS. These lymphomas are generally high-grade, of B-cell origin, and often involve extranodal sites. Reported here are twenty patients with AIDS in whom symptoms and physical findings developed related to the head and neck region as a result of lymphoma. The tumor was observed in a variety of sites, including the nasopharynx, orbit, submandibular triangle, anterior and posterior cervical triangles, supraclavicular fossa, and the hypopharynx. Sixteen tumors were large cell nonHodgkin's B-cell lymphomas, three were small cell nonHodgkin's B-cell lymphomas, and one was Hodgkin's disease, mixed cellularity. All were treated with combination chemotherapy. A high degree of suspicion for lymphoma is required in treating any patient with AIDS who has a rapidly enlarging mass in the head and neck. If needle aspiration is nondiagnostic, excisional biopsy should be performed after a complete head and neck evaluation. Although the development of lymphoma associated with AIDS portends a grave prognosis, prompt diagnosis will allow an improved chance of remission of the lymphoma.  相似文献   
6.
The paper presents the reasoning mechanism of COR, a knowledge-based system (KBS) able to provide support for the diagnosis of coronaric ischemia by integrating the interpretation of chest pain, 12-lead ECG, and bio-marker concentrations. Chest pain features are collected interactively through a questionnaire. The ECG signal is acquired in SCP format. Any set of bio-markers can be considered. Data input is incremental and possibly incomplete. Reasoning is based on revised uncertainty calculus, which allows a formal treatment of verbally expressed uncertainty concerning both input data and diagnostic rules. Each diagnosis is supplemented by a linguistic label, expressing the plausibility of the disease identified, given the symptoms observed.  相似文献   
7.
Neuroendocrine cell markers for pancreatic islets and tumors.   总被引:1,自引:0,他引:1  
The authors review the application of a variety of neuroendocrine cell markers to identify pancreatic islet cells and tumors. In the past, several empiric histochemical techniques had been used to demonstrate neuroendocrine cells, particularly the Grimelius argyrophilic stain. The development of immunohistochemistry made it possible to demonstrate specific cell products such as regulatory peptides, thus allowing the classification of pancreatic neuroendocrine tumors with a view to clinical symptoms. However, it is not always possible to visualize regulatory peptides in these tumors. It is therefore important to use broad-spectrum neuroendocrine cell markers to identify the neuroendocrine nature. These markers are proteins localized in the secretory granules (core- or membrane-related), in the cytosol, or in the cellular membrane. The markers most commonly used in routine histopathology are the secretory granule proteins chromogranin A and synaptophysin and the cytosolic enzyme neuronspecific enolase. Other new markers (e.g., synaptic vesicle protein 2) are of general diagnostic value. Region-specific antibodies to chromogranin A can be valuable in differentiating between benign and malignant neuroendocrine tumors. Some markers may be related to the functioning characteristics of pancreatic neuroendocrine tumors, such as prohormone convertases. In addition, markers giving further complementary information have been identified, such as five somatostatin receptor subtypes, the expression of which varies markedly in pancreatic neuroendocrine tumors. Antibodies against all somatostatin receptor subtypes are now commercially available, and immunohistochemical investigation of its expression should be routinely applied when considering treatment with somatostatin analogs.  相似文献   
8.
Two different polymorphic regions of the interleukin-6 (IL-6) gene were investigated in patients with Alzheimer's disease (AD) and non-demented controls. The -174 C allele in the promoter region of IL-6 gene was over-represented in AD patients compared to controls and significantly increased the risk of AD. Moreover, the -174 CC genotype was associated with a high risk of the disease in women. The D allele of a variable number of tandem repeat (VNTR) was in strong linkage disequilibrium with the -174 C allele and slightly increased AD risk. On the other hand, the frequency of the VNTR C allele was decreased in patients with AD and was negatively associated with the risk of developing AD. Both the -174 CC and VNTR DD genotypes were also associated with increased IL-6 levels in the blood and brain from AD. These findings suggest that IL-6 may play a multifaceted role in AD by affecting the turnover of the cytokine.  相似文献   
9.
BACKGROUND: The European tick, Argas reflexus, is an urban pest parasitizing urban pigeons and may cause a wide range of allergic reactions. METHODS: Specific IgE to A. reflexus, SDS-PAGE and IgE immunoblotting, performed with tick extract, were carried out in the sera of 6 patients who reported allergic reactions after tick bite. RESULTS: Specific IgE to A. reflexus (RAST class ranging from 1 to 3) were detected in the sera of 6 patients who reported allergic reactions (urticaria and angioedema in 2 and anaphylaxis in the other 4 patients) after tick bite. IgE reactivity to two bands of 22 and 40 kDa were identified in the patient sera. CONCLUSIONS: Allergy to A. reflexus has to be considered in allergic patients living in buildings where pigeons have their nests. The powerful sensitizing property of tick allergen is underlined by the observation that none of our patients was atopic.  相似文献   
10.
Autosomal-recessive osteopetrosis is a severe genetic disease caused by osteoclast failure. Approximately 50% of the patients harbor mutations of the ATP6i gene, encoding for the osteoclast-specific a3 subunit of V-ATPase. We found inactivating ATP6i mutations in four patients, and three of these were novel. Patients shared macrocephaly, growth retardation and optic nerve alteration, osteosclerotic and endobone patterns, and high alkaline phosphatase and parathyroid hormone levels. Bone biopsies revealed primary spongiosa lined with active osteoblasts and high numbers of tartrate-resistant acid phosphatase (TRAP)-positive, a3 subunit-negative, morphologically unremarkable osteoclasts, some of which located in shallow Howship lacunae. Scarce hematopoietic cells and abundant fibrous tissue containing TRAP-positive putative osteoclast precursors were noted. In vitro osteoclasts were a3-negative, morphologically normal, with prominent clear zones and actin rings, and TRAP activity more elevated than in control patients. Podosomes, alphaVbeta3 receptor, c-Src, and PYK2 were unremarkable. Consistent with the finding in the bone biopsies, these cells excavated pits faintly stained with toluidine blue, indicating inefficient bone resorption. Bone marrow transplantation was successful in all patients, and posttransplant osteoclasts showed rescue of a3 subunit immunoreactivity.  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