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   8729篇
  免费   573篇
  国内免费   7篇
耳鼻咽喉   35篇
儿科学   199篇
妇产科学   122篇
基础医学   1062篇
口腔科学   106篇
临床医学   1370篇
内科学   1653篇
皮肤病学   61篇
神经病学   1003篇
特种医学   409篇
外科学   842篇
综合类   70篇
一般理论   3篇
预防医学   906篇
眼科学   115篇
药学   598篇
中国医学   64篇
肿瘤学   691篇
  2023年   55篇
  2022年   74篇
  2021年   165篇
  2020年   118篇
  2019年   145篇
  2018年   202篇
  2017年   158篇
  2016年   173篇
  2015年   222篇
  2014年   272篇
  2013年   409篇
  2012年   612篇
  2011年   702篇
  2010年   381篇
  2009年   329篇
  2008年   623篇
  2007年   625篇
  2006年   557篇
  2005年   549篇
  2004年   489篇
  2003年   449篇
  2002年   434篇
  2001年   104篇
  2000年   88篇
  1999年   109篇
  1998年   73篇
  1997年   61篇
  1996年   57篇
  1995年   54篇
  1994年   42篇
  1993年   46篇
  1992年   64篇
  1991年   68篇
  1990年   56篇
  1989年   50篇
  1988年   46篇
  1987年   71篇
  1986年   50篇
  1985年   65篇
  1984年   41篇
  1983年   43篇
  1982年   21篇
  1981年   25篇
  1980年   22篇
  1979年   27篇
  1978年   33篇
  1977年   24篇
  1976年   20篇
  1971年   24篇
  1970年   20篇
排序方式: 共有9309条查询结果,搜索用时 0 毫秒
1.
The purpose of this study was to determine whether blood lipid and lipoprotein concentrations varied in 5 men with advanced HIV-1 infection after 12 months of aerobic exercise training. Prior to exercise, the mean baseline cholesterol and high-density lipoprotein cholesterol (HDL-C) serum concentration were each lower, and mean baseline triglyceride concentration was higher compared to a healthy population norm. Consistent exercise training for 12 months failed to significantly (p > .05) alter cholesterol or HDL-C. Triglyceride concentration was significantly (p < .05) elevated above baseline (63 mg/dL) regardless of exercise compliance. The results suggest that long-term exercise training cannot correct lipid profile abnormality, particularly hypertriglyceridemia, common to individuals with advanced HIV-1 infection.  相似文献   
2.
3.
4.

Background  

Shoulder disorders are a common health problem in western societies. Several treatment protocols have been developed for the clinical management of persons with shoulder pain. However available evidence does not support any protocol as being superior over others. Systematic reviews provide some evidence that certain physical therapy interventions (i.e. supervised exercises and mobilisation) are effective in particular shoulder disorders (i.e. rotator cuff disorders, mixed shoulder disorders and adhesive capsulitis), but there is an ongoing need for high quality trials of physical therapy interventions. Usually, physical therapy consists of active exercises intended to strengthen the shoulder muscles as stabilizers of the glenohumeral joint or perform mobilisations to improve restricted mobility of the glenohumeral or adjacent joints (shoulder girdle). It is generally accepted that a-traumatic shoulder problems are the result of impingement of the subacromial structures, such as the bursa or rotator cuff tendons. Myofascial trigger points (MTrPs) in shoulder muscles may also lead to a complex of symptoms that are often seen in patients diagnosed with subacromial impingement or rotator cuff tendinopathy. Little is known about the treatment of MTrPs in patients with shoulder disorders.  相似文献   
5.
The adequate treatment of methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis has intrigued clinicians for some time. As the resistance of these pathogens, coupled with the increase in community-acquired cases, continues steadily to rise, clinicians are finding it useful to employ multi-modal approaches for efficacious treatment. The authors present a single case report of a patient with recurrent MRSA osteomyelitis, lumbar paraspinal and epidural abscess. He was found to have decreased muscle strength and was hyporeflexic in the involved extremity. Serum testing demonstrated MRSA bacteremia. Neuroimaging studies revealed evidence of paraspinal abscess and a presumed herniated nucleus pulposus at the L5/S1 interspace with significant nerve root compromise. Despite antimicrobials, his symptoms persisted, necessitating surgical exploration. At surgery, paraspinal and epidural abscesses were encountered and debrided; however, no herniated disc was visualized. This case demonstrates the diagnostic and therapeutic dilemmas with which these lesions present. We postulate that the MRSA osteomyelitis/discitis pathogens were walled off in the disc space and subsequently inoculated the soft tissues with ensuing bacteremia. We concur that antimicrobial treatment should be the first line of therapy for these patients; however, surgical debridements and cautious spinal instrumentation should be employed where appropriate.  相似文献   
6.
Guidelines for design of clinical trials evaluating behavioral headache treatments were developed to facilitate production of quality research evaluating behavioral therapies for management of primary headache disorders. These guidelines were produced by a Workgroup of headache researchers under auspices of the American Headache Society. The guidelines are complementary to and modeled after guidelines for pharmacological trials published by the International Headache Society, but they address methodologic considerations unique to behavioral and other nonpharmacological treatments. Explicit guidelines for evaluating behavioral headache therapies are needed as the optimal methodology for behavioral (and other nonpharmacologic) trials necessarily differs from the preferred methodology for drug trials. In addition, trials comparing and integrating drug and behavioral therapies present methodological challenges not addressed by guidelines for pharmacologic research. These guidelines address patient selection, trial design for behavioral treatments and for comparisons across multiple treatment modalities (eg, behavioral vs pharmacologic), evaluation of results, and research ethics. Although developed specifically for behavioral therapies, the guidelines may apply to the design of clinical trials evaluating many forms of nonpharmacologic therapies for headache.  相似文献   
7.
Prior to 1975, Stingy Run was a third-order tributary of Kyger Creek, which empties into the Ohio River at Mile 260 (Gallia County, Ohio). Both streams drained strip mine refuse areas and physicochemical measurements indicated acidicmine drainage conditions (e.g., low pH). A depauperate macroinvertebrate community, dominated by a few acid-tolerant taxa, was found in both streams and no fishes were collected. In 1974, Stingy Run was impounded to form a fly ash pond which contains fly ash sluiced from Ohio Power Company's General James M. Gavin coal-fired power plant. Physicochemical and biological sampling during 1975–1986 indicated marked changes in the aquatic ecology of Stingy Run between 1) pre-impoundment and post-impoundment conditions; and 2) effluent pH control treatments after impoundment. Fly ash discharge eliminated acidicmine drainage characteristics in Stingy Run and lower Kyger Creek. After impoundment, net spinning caddisflies and a few dipteran taxa dominated the Stingy Run benthic community, reflecting changes in functional niches likely due to improved habitat and greater food availability. Replacement of acid feed by CO2 injection for effluent pH control and changes in ash pond chemistry occurred concomitant with elimination of a substrate floc; increased species richness and densities of invertebrates were subsequently observed. In Stingy Run, species richness and diversity of fishes increased from 1983 to 1986, reflecting improved water quality and increased benthic production after impoundment. Many of these fishes are opportunistic feeders on drifting insects.  相似文献   
8.
(11)C-meta-Hydroxyephedrine (HED) is used in cardiac PET as an index of norepinephrine (NE) reuptake transporter (NET) density and synaptic NE levels. Whereas cardiac uptake is well documented, tracer retention in other tissues with rich noradrenergic innervation is unclear. Dysfunctional sympathetic nervous system (SNS) function in extracardiac metabolic storage tissues (i.e., adipose tissue and skeletal muscle) and endocrine organs contributes to several disorders. The aim of this study was to determine the potential of HED as an index of NE function in brown adipose tissue, lung, pancreas, skeletal muscle, and kidney by identifying NET-specific retention and determining the presence of radiolabeled metabolites. METHODS: Male Sprague-Dawley rats were administered HED and sacrificed at 30 min after tracer injection. Tissues were rapidly excised and counted for radioactivity, and relative tracer retention was quantified. Pretreatment with NET inhibitors established specific HED accumulation. The effect of elevated NE was tested by subcutaneous minipump NE infusion or inhibition of monoamine oxidase. Column-switch high-performance liquid chromatography (HPLC) was used to analyze the presence of radiolabeled metabolites in heart, brown adipose tissue, pancreas, and plasma. RESULTS: NET-specific retention was observed in heart, brown adipose tissue, lung, and pancreas but not in liver, skeletal muscle, or kidney. A dose-dependent response of HED accumulation to treatments elevating NE levels was established in tissues exhibiting specific uptake. At 30 min after tracer administration, HPLC analysis revealed 93%-95% of total radioactivity signal derived from unchanged HED in heart, pancreas, and brown adipose tissue compared with 61% +/- 8% unchanged HED in plasma. CONCLUSION: In addition to the heart, lung, pancreas, and brown adipose tissue exhibit specific and NE-responsive uptake of HED, supporting the potential for novel PET studies of SNS integrity in these tissues.  相似文献   
9.
Impaired recall for early items (primacy) and late items (recency) on word list recall tests are seen in Alzheimer's disease (AD). We compared conventional scoring on the Telephone Instrument for Cognitive Status (TICS) recall list with scorings based on retention-weighted recall (RWR: each item weighted by its serial position) in older adults participating in a community-based aging study. Subjects with mild AD (N=18) did not differ from those without dementia (N=231) with respect to recency (46% vs. 59%, p = 0.2), but had impaired primacy (2% vs. 39%, p < .001) on word recall on the TICS. RWR scoring improved the effect size (1.52 SD) compared to conventional scoring (1.08 SD). With a fixed sensitivity of 85%, specificity was lower using conventional scoring (56%) than RWR (76%) scoring. Our findings suggest that optimized RWR scoring of word list free recall can improve detection of mild AD compared to conventional scoring.  相似文献   
10.
Migraine is a highly prevalent headache disorder that has a substantial impact on the individual and society. Over the past decade, substantial advances in research have increased understanding of the pathophysiology, diagnosis, epidemiology, and treatment of the disorder. This article reviews the burden of migraine, emphasizing the population-based studies that used standardized diagnostic criteria.  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