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   11776篇
  免费   735篇
  国内免费   92篇
耳鼻咽喉   97篇
儿科学   358篇
妇产科学   292篇
基础医学   1588篇
口腔科学   153篇
临床医学   1040篇
内科学   2961篇
皮肤病学   143篇
神经病学   1637篇
特种医学   410篇
外科学   1038篇
综合类   31篇
一般理论   7篇
预防医学   588篇
眼科学   145篇
药学   902篇
中国医学   13篇
肿瘤学   1200篇
  2024年   27篇
  2023年   192篇
  2022年   310篇
  2021年   540篇
  2020年   308篇
  2019年   442篇
  2018年   486篇
  2017年   365篇
  2016年   423篇
  2015年   430篇
  2014年   616篇
  2013年   724篇
  2012年   994篇
  2011年   1004篇
  2010年   583篇
  2009年   512篇
  2008年   737篇
  2007年   687篇
  2006年   677篇
  2005年   607篇
  2004年   473篇
  2003年   394篇
  2002年   352篇
  2001年   52篇
  2000年   48篇
  1999年   72篇
  1998年   57篇
  1997年   50篇
  1996年   51篇
  1995年   41篇
  1994年   37篇
  1993年   25篇
  1992年   24篇
  1991年   34篇
  1990年   24篇
  1989年   31篇
  1988年   30篇
  1987年   17篇
  1986年   24篇
  1985年   15篇
  1984年   10篇
  1983年   14篇
  1982年   8篇
  1981年   10篇
  1980年   6篇
  1979年   9篇
  1978年   7篇
  1977年   7篇
  1967年   2篇
  1966年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.

Background

The reduction of hospitalizations in patients with heart failure (HF) may have clinical and economical implications.

Materials and methods

In a case-control study, we compared the number of hospital admissions for congestive HF during the same follow-up period in two homogeneous groups of patients, each consisting of 27 consecutive patients treated with biventricular pacing and back-up defibrillator (B-ICD) in our institution. The first group was implanted with an InSync Sentry®, (Medtronic Inc, Minneapolis, MN, US), a B-ICD device with the OptiVol®feature for monitoring intrathoracic fluid accumulation and equipped with an active acoustic alarm (Group 1); the second group was implanted with an InSync III Marquis?(Medtronic), a B-ICD device with similar features except for the absence of the OptiVol (Group 2). Follow-up visits were performed at 3 month interval or in case of acoustic alarm.

Results

The patient clinical characteristics of the two groups were similar. In Group 1, with 359?±?98 days follow-up, 12 of the 27 patients, experienced 18 OptiVol alarms with only one hospital admission for congestive HF occurring in a patient who ignored the acoustic alarm for 13 days. In Group 2, eight HF hospitalizations occurred in seven patients (p?

Conclusions

The OptiVol feature is a useful tool for the clinical management of HF patients as it can result in early treatment during the pre-clinic stage of HF decompensation and in a significant reduction of hospital admissions for congestive HF.
  相似文献   
992.
In patients with symptoms of heart failure, identifying the underlying cause of cardiomyopathy is helpful to establish the diagnosis and to guide therapy. The differential diagnosis of cardiomyopathy can be challenging based on clinical findings. We report the case of a patient who represented a clinical dilemma (cardiac sarcoidosis or ischaemic heart disease), in whom cardiovascular magnetic resonance was a clinically valuable tool to distinguish dual cardiac pathology due to its unique, non-invasive, tissue characterization capabilities.  相似文献   
993.
OBJECTIVE: To clarify whether an altered redox state persists in the subacute phase of myocardial infarction and if specific redox patterns are associated with later cardiac events. METHODS: Ninety-seven patients [80 men, median 63 (interquartile range, 53, 69) years] with a first acute myocardial infarction, with (53%) or without ST segment elevation, treated with successful percutaneous interventions, were tested at 5-6 days after admission for plasma alpha-tocopherol, ascorbic acid, total and reduced homocysteine, cysteine, glutathione, cysteinylglycine and blood-reduced glutathione, all assessed by high-pressure liquid chromatography. Free malondialdehyde was evaluated by gas chromatography. A subgroup of 14 patients had adjunctive blood samples within 1 h and at 72 h after angioplasty. Blood samples from 44 patients matched for age, sex, and risk factors served as controls. Patients were followed up for median 15 (interquartile range, 9, 17) months for cardiac events. RESULTS: All plasma-reduced aminothiols, vitamins and plasma total glutathione were significantly lower in myocardial infarction at 5-6 days than in controls. In the 14 myocardial infarction patients sampled repeatedly, plasma-reduced glutathione, cysteinylglycine, total glutathione, and alpha-tocopherol significantly decreased, whereas blood-reduced glutathione, total homocysteine, and cysteine significantly increased over time. During follow-up, 20 of 97 (21%) patients had adverse cardiac events. Multivariate analysis revealed that only plasma-reduced glutathione was independently associated with events (hazard ratio 0.42, 95% confidence interval 0.18-0.99, P=0.04). CONCLUSIONS: Acute myocardial infarction patients have an altered redox state at 5-6 days after successful reperfusion with respect to controls. Low plasma levels of reduced glutathione at discharge are associated with cardiac events at follow-up.  相似文献   
994.
BACKGROUND: We have previously described two cases of HIV-1-positive patients undergoing surgery for stenosis of the internal carotid arteries. Histology revealed an extensive inflammatory infiltration of the vascular wall and no evidence of atheromasic plaque. This unexpected pattern of carotid damage prompted us to perform a more accurate investigation of the characteristics of carotid plaques in a group of HIV-positive patients. The results were compared with those obtained from young patients affected by atherosclerosis of the epi-aortic vessels and patients with arteritis. METHODS: The patients underwent ultrasonography of the epi-aortic vessels using one of the latest generation power color-Doppler with 7.5 MHz probes. RESULTS: The study population included 61 HIV-positive patients and 47 HIV-negative patients (37 atherosclerotic and 10 with arteritis). Compared with HIV-negative atherosclerotic patients, there were significantly higher proportions of HIV-positive patients with iso-hypoechogenic lesions (81.8 vs. 29%) that were homogeneous both in their parietal and endoluminal portions (96.7 vs. 21.6% and 88.5 vs. 54.0%, respectively), with a smooth or slightly irregular surface (99.0 vs. 56.7%) (P=0.001 for all differences). No statistically significant differences were seen between HIV-positive and arteritis patients. CONCLUSION: Our study evidenced that the ultrasonographic structure of the epi-aortic lesions in HIV-positive patients substantially differ from those of the plaques in atherosclerotic patients, although they share similar characteristics with patients affected by arteritis. Further investigations are warranted to better define the structure and the mechanism of onset of these lesions.  相似文献   
995.
Renal cancer     
In Europe, renal cancer (that is neoplasia of the kidney, renal pelvis or ureter (ICD-9 189 and ICD-10 C64-C66)) ranks as the seventh most common malignancy in men amongst whom there are 29,600 new cases each year (3.5% of all cancers). Tobacco, obesity and a diet poor in vegetables are all acknowledged risk factors, along with specific occupational and environmental factors. A familial history of renal carcinoma is also likely to increase the risk. Renal carcinoma may remain clinically occult for most of its course. The classic presentation of pain, haematuria, and flank mass occurs in only 9% of patients and is often indicative of advanced disease. Approximately 30% of patients with renal carcinoma present with metastatic disease, 25% with locally advanced renal carcinoma and 45% with localized disease. Metastases are typically found in the lung, soft tissue, bone, liver, cutaneous sites, and central nervous system. The most important staging technique is a computed tomography (CT) scan of the whole abdomen. Survival rates are more favourable for patients with tumours confined to the kidney. Five-year survival for patients with metastatic renal carcinoma is comprised between 0 and 20%. Radical nephrectomy is the standard intervention for renal cancer. Intrinsic resistance to chemotherapy has long been a hallmark of renal carcinoma. Limited options are available for the systemic therapy, and no chemotherapeutic regimen is accepted as a standard of care. Biologic agents represent the major effective therapies for widespread metastatic renal cancer. An antiangiogenic strategy, the neutralization of VEGF, can slow the growth rate of advanced cancer.  相似文献   
996.
997.

Objective

To compare the clinical aspects of peripheral neuropathy associated with Wegener''s granulomatosis (WG), Churg–Strauss syndrome (CSS) and microscopic polyangiitis (MP).

Methods

Cohort study conducted in a single university hospital. Patients were included when a definite diagnosis of WG, CSS or MP was made according to the current classification criteria in our hospital, between 1999 and 2006. All patients underwent periodically clinical and electrophysiological screening for peripheral neuropathy, assessment of disability, and clinical and laboratory evaluation during a mean follow‐up of 38 months.

Results

Sixty‐four consecutive patients diagnosed with WG (26 patients), CSS (26 patients) and MP (12 patients) were recruited. Peripheral neuropathy occurred in 27/64 patients: six with WG, 15 with CSS and six with MP. Neuropathy occurred earlier in the disease history in CSS and MP compared with WG. Among patients with WG, those who developed peripheral neuropathy during follow‐up were older than those without neuropathy both at the time of onset and of diagnosis of vasculitis. Distal symmetric polyneuropathy was present in 11 patients, and single or multiple mononeuropathy in 16. Patients with WG had a less severe form of mononeuritis multiplex than CSS or MPA patients. Disability and pain were greater in patients with mononeuropathy, although one‐third of them were painless. Relapses of neuropathy were extremely infrequent.

Conclusions

Peripheral neuropathy in WG occurs less frequently, later in the disease course and in a milder form than in CSS and MP. Single or multiple mononeuropathy associated with these subsets of vasculitis can often be painless.Wegener''s granulomatosis (WG), Churg–Strauss syndrome (CSS) and microscopic polyangiitis (MP) constitute a group of small vessel systemic vasculitides (SVSVs), involving preferentially venules, capillaries and arterioles, that share common histological features. They are often referred to as “pauci‐immune” SVSVs, because of the scarceness of immune complex deposition, or as “ANCA associated” SVSVs because antineutrophil cytoplasmic antibodies (ANCA) are often found in the serum of patients.1,2 Despite this nomenclature, ANCA may be absent in some patients in all three subsets, but more often in CSS. While the diagnostic relevance of ANCA is widely accepted, there is still debate on their possible, if any, pathogenetic role.3,4,5,6 The main distinctive features of the three subsets include: necrotising granulomatous inflammation in the absence of asthma for WG, asthma, eosinophilia and necrotising granulomatous inflammation for CSS and absence of both granulomatous inflammation and asthma for MP.SVSVs can affect virtually any organ system in the body, resulting in a wide variety of signs and symptoms. The peripheral nervous system represents no exception, being frequently involved, and may also be an initial manifestation of the clinical picture.7,8 Pathogenesis is linked to a primary process of inflammation and of the vessel wall, resulting in blood flow impairment and, ultimately, in ischaemia of the supplied tissues. However, vasculitic processes with very similar histological features and anatomical distribution may determine heterogeneous clinical pictures and outcomes.9,10 In this study, we evaluated 64 consecutive patients diagnosed with pauci‐immune SVSV in order to determine differences in the involvement of the peripheral nervous system in the three subsets.  相似文献   
998.
We report a case of a Parkinson's disease patient treated by bilateral deep brain stimulation of the subthalamic nucleus, who developed freezing and hypokinesia of gait induced by stimulation through a left-side misplaced electrode which was more antero-medial than the planned trajectory. Subsequently, correct repositioning of the left electrode afforded complete relief of gait disturbances. Freezing and hypokinesia of gait may be side effects of deep brain stimulation of the subthalamic region due to current spreading antero-medially to the subthalamic nucleus. These side effects are not subject to habituation and restrict any increase in stimulation parameters. We hypothesize that pallidal projections to the pedunculopontine nucleus could be responsible for these gait disturbances in our patient.  相似文献   
999.
We assessed the involvement of cutaneous innervation in two subjects with a molecularly confirmed diagnosis of spinobulbar muscular atrophy (SBMA) using antidromic nerve conduction studies, quantitative sensory testing, and sweat tests, as well as immunohistochemical techniques and confocal microscopy of glabrous and hairy skin biopsy. Both patients showed a marked reduction in amplitude of sensory action potentials and moderate or severe abnormalities of tactile thresholds and mechanical pain perception. A severe reduction of sweat drops on the Silastic imprint test and a widespread loss of small myelinated and unmyelinated fibers in hairy skin were also observed. Fiber loss involved either somatic or autonomic fibers and did not show any distal-proximal gradient. These results, together with loss of Meissner corpuscles and their large myelinated afferent fibers in glabrous skin, confirmed the extensive involvement of sensory neurons of large and small size and revealed an autonomic skin denervation in SBMA.  相似文献   
1000.
We report on a girl presenting with mental retardation, craniofacial dysmorphisms, and syndactyly. The child's mother and maternal grandfather presented bilateral syndactyly of toes 2 and 3. These manifestations, falling within the ambit of what has been termed the craniodigital syndromes, were first reported by Scott et al (1971) in 3 brothers.  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