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   1322篇
  免费   180篇
  国内免费   34篇
耳鼻咽喉   16篇
儿科学   44篇
妇产科学   57篇
基础医学   311篇
口腔科学   22篇
临床医学   123篇
内科学   176篇
皮肤病学   12篇
神经病学   79篇
特种医学   190篇
外科学   146篇
综合类   45篇
一般理论   1篇
预防医学   114篇
眼科学   16篇
药学   89篇
中国医学   1篇
肿瘤学   94篇
  2021年   8篇
  2019年   12篇
  2018年   10篇
  2017年   8篇
  2016年   12篇
  2015年   26篇
  2014年   27篇
  2013年   27篇
  2012年   45篇
  2011年   51篇
  2010年   42篇
  2009年   58篇
  2008年   53篇
  2007年   67篇
  2006年   66篇
  2005年   50篇
  2004年   45篇
  2003年   32篇
  2002年   56篇
  2001年   53篇
  2000年   29篇
  1999年   39篇
  1998年   37篇
  1997年   38篇
  1996年   29篇
  1995年   28篇
  1994年   17篇
  1993年   21篇
  1992年   29篇
  1991年   18篇
  1990年   40篇
  1989年   46篇
  1988年   60篇
  1987年   48篇
  1986年   40篇
  1985年   27篇
  1984年   28篇
  1983年   16篇
  1982年   14篇
  1981年   12篇
  1979年   13篇
  1978年   10篇
  1977年   11篇
  1975年   15篇
  1974年   15篇
  1973年   10篇
  1972年   20篇
  1971年   10篇
  1970年   9篇
  1968年   11篇
排序方式: 共有1536条查询结果,搜索用时 31 毫秒
51.
AimsDiabetic foot ulcers (DFUs) and ulceration are complex and lifelong problems for patients with diabetes which dramatically increase mortality rates. This qualitative study sought to capture detailed personal accounts and insights from patients with a clinical history of DFUs and amputations to better understand patient experiences.MethodsFifteen patients from a tertiary referral center that treats diabetic foot problems were approached for participation. Inclusion criteria included having at least one DFU and being of white, Native American, or Hispanic background. Interviews were conducted by telephone by study staff trained in qualitative data gathering and audio recorded.ResultsThe main themes that emerged around impacts included the heavy burden of managing care, significant loss of ambulatory function, economic stress due to medical care costs and job loss, and emotional suffering tied to these stressors.ConclusionsThese data illuminate common social and personal impacts of diabetic foot problems across an ethnically and racially diverse and predominantly low-income US sample that expand our understanding of related declines in well-being. Our results indicate a need for proactive mental health assessment post DFUs diagnosis and the diversification of hospital and community-based support systems.  相似文献   
52.
53.
BACKGROUND: Endovascular radiation is emerging as a potential solution for the prevention and treatment of restenosis. Its effects on the morphology of unstented vessels cannot be determined by angiography and therefore require the use of intravascular ultrasound. METHODS AND RESULTS: Through a 5F noncentered catheter for delivery of a 90Sr/Y source train, 12, 14, or 16 Gy at 2 mm was delivered to native coronary arteries after successful balloon angioplasty in 30 patients. Four patients required stent deployment in the first week. Quantitative coronary angiography and IVUS were performed during the initial procedure and at 6-month follow-up. Binary angiographic restenosis was present in 3 of 30 patients, with target lesion and vessel revascularization performed in 3 and 5 patients, respectively. Angiographic late loss was -0.02+/-0.60 mm, with a -0.09+/-0.46 loss index. IVUS demonstrated no significant reduction in lumen area (from 5.69+/-1.72 mm2 after treatment to 6. 04+/-2.63 mm2 at follow-up), with no significant change in external elastic membrane area (13.71+/-4.54 to 14.22+/-4.71 mm2) over the 6-month follow-up. Wall area was 8.01+/-3.85 mm2 after radiation therapy and 8.19+/-3.44 mm2 at follow-up (P=NS). No significant differences were noted between the different dose groups. CONCLUSIONS: beta-Radiation therapy resulted in a low restenosis rate with negligible late loss by angiography. By IVUS, beta-radiation was shown to inhibit neointima formation, with no reduction of total vessel area at 6-month follow-up.  相似文献   
54.
Recently, a hexanucleotide (GGGGCC) repeat expansion in the first intron of C9ORF72 was reported as the cause of chromosome 9p21‐linked frontotemporal dementia‐amyotrophic lateral sclerosis (FTD‐ALS). We here report the prevalence of the expansion in a hospital‐based cohort and associated clinical features indicating a wider clinical spectrum of C9ORF72 disease than previously described. We studied 280 patients previously screened for mutations in genes involved in early onset autosomal dominant inherited dementia disorders. A repeat‐primed polymerase chain reaction amplification assay was used to identify pathogenic GGGGCC expansions. As a potential modifier, confirmed cases were further investigated for abnormal CAG expansions in ATXN2. A pathogenic GGGGCC expansion was identified in a total of 14 probands. Three of these presented with atypical clinical features and were previously diagnosed with clinical olivopontocerebellar degeneration (OPCD), atypical Parkinsonian syndrome (APS) and a corticobasal syndrome (CBS). Further, the pathogenic expansion was identified in six FTD patients, four patients with FTD‐ALS and one ALS patient. All confirmed cases had normal ATXN2 repeat sizes. Our study widens the clinical spectrum of C9ORF72related disease and confirms the hexanucleotide expansion as a prevalent cause of FTD‐ALS disorders. There was no indication of a modifying effect of the ATXN2 gene.  相似文献   
55.
AIM: To determine the prevalence of bipolar disorder (BD) and sub-threshold symptoms in children with attention deficit hyperactivity disorder (ADHD) through 14 years’ follow-up, when participants were between 21-24 years old.METHODS: First, we examined rates of BD type I and II diagnoses in youth participating in the NIMH-funded Multimodal Treatment Study of ADHD (MTA). We used the diagnostic interview schedule for children (DISC), administered to both parents (DISC-P) and youth (DISCY). We compared the MTA study subjects with ADHD (n = 579) to a local normative comparison group (LNCG, n = 289) at 4 different assessment points: 6, 8, 12, and 14 years of follow-ups. To evaluate the bipolar variants, we compared total symptom counts (TSC) of DSM manic and hypomanic symptoms that were generated by DISC in ADHD and LNCG subjects. Then we sub-divided the TSC into pathognomonic manic (PM) and non-specific manic (NSM) symptoms. We compared the PM and NSM in ADHD and LNCG at each assessment point and over time. We also evaluated the irritability as category A2 manic symptom in both groups and over time. Finally, we studied the irritability symptom in correlation with PM and NSM in ADHD and LNCG subjects.RESULTS: DISC-generated BD diagnosis did not differ significantly in rates between ADHD (1.89%) and LNCG 1.38%). Interestingly, no participant met BD diagnosis more than once in the 4 assessment points in 14 years. However, on the symptom level, ADHD subjects reported significantly higher mean TSC scores: ADHD 3.0; LNCG 1.7; P < 0.001. ADHD status was associated with higher mean NSM: ADHD 2.0 vs LNCG 1.1; P < 0.0001. Also, ADHD subjects had higher PM symptoms than LNCG, with PM means over all time points of 1.3 ADHD; 0.9 LNCG; P = 0.0001. Examining both NSM and PM, ADHD status associated with greater NSM than PM. However, Over 14 years, the NSM symptoms declined and changed to PM over time (df 3, 2523; F = 20.1; P < 0.0001). Finally, Irritability (BD DSM criterion-A2) rates were significantly higher in ADHD than LNCG (χ2 = 122.2, P < 0.0001), but irritability was associated more strongly with NSM than PM (df 3, 2538; F = 43.2; P < 0.0001).CONCLUSION: Individuals with ADHD do not appear to be at significantly greater risk for developing BD, but do show higher rates of BD symptoms, especially NSM. The greater linkage of irritability to NSM than to PM suggests caution when making BD diagnoses based on irritability alone as one of 2 (A-level) symptoms for BD diagnosis, particularly in view of its frequent presentation with other psychopathologies.  相似文献   
56.
Recent evidence indicates that cyclin-dependent kinases (CDKs, cdks) may be inappropriately activated in several neurodegenerative conditions. Here, we report that cdk5 expression and activity are elevated after administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a toxin that damages the nigrostriatal dopaminergic pathway. Supporting the pathogenic significance of the cdk5 alterations are the findings that the general cdk inhibitor, flavopiridol, or expression of dominant-negative cdk5, and to a lesser extent dominant-negative cdk2, attenuates the loss of dopaminergic neurons caused by MPTP. In addition, CDK inhibition strategies attenuate MPTP-induced hypolocomotion and markers of striatal function independent of striatal dopamine. We propose that cdk5 is a key regulator in the degeneration of dopaminergic neurons in Parkinson's disease.  相似文献   
57.
PurposeTo evaluate the effect of Haishengsu (HSS), a protein extract from Tegillarca granosa, on multidrug-resistance genes mdr1, BCR/ABL and sorcin in transplanted tumors.Material/MethodsMice were inoculated subcutaneously with a drug resistant leukemia cell line K562/ADM. Tumor-bearing animals were divided into control, adriamycin, HSS and combination therapy (adriamycin plus HSS) groups. Flow cytometry was used to detect apoptosis of tumor cells, and RT-PCR was used to evaluate the expression of mdr1, BCR/ABL and sorcin.ResultsThe apoptosis rate in the high (71.8%), medium (72.3%) and low doses HSS group (72.4%) was higher than in control (1.2%, p<0.01), adriamycin (34.4%, p<0.05) or combination therapy group (46.4%, p<0.05). The mean optical density of mdr1, BCR/ABL and sorcin in HSS groups was lower than in control, adriamycin and combination therapy group (p<0.01). The optical density of the three genes in high HSS group was lower than in medium and low HSS group (p<0.01).ConclusionsHaishengsu promotes apoptosis of drug-resistant K562/ADM tumors in mice in a dose-dependent manner. The pro-apoptotic effect of Haishengsu may be related to a reduced expression of multidrug-resistance genes mdr1, BCR/ABL and sorcin.  相似文献   
58.
Coxsackievirus B3 (CVB3) is a major cause of acute myocarditis, a serious condition that is refractory to treatment. Myocardial damage results in tissue remodeling that, if too extensive, may contribute to disease. Remodeling is achieved by extracellular proteolysis mediated by the matrix metalloproteinases (MMPs), and MMP activity is counterbalanced by tissue inhibitors of MMPs (TIMPs). We show herein that TIMP-1 expression is induced in the myocardium by CVB3 infection. Surprisingly, TIMP-1 knockout mice exhibited a profound attenuation of myocarditis, with increased survival. The amelioration of disease in TIMP-1 knockout mice was not attributable to either an altered T-cell response to the virus or to reduced viral replication. These data led us to propose a novel function for TIMP-1: its highly localized up-regulation might arrest the MMP-dependent migration of inflammatory cells at sites of infection, thereby anatomically focusing the adaptive immune response. The benefits of TIMP-1 blockade in treating viral myocarditis were confirmed by administering, to wild-type animals, TIMP-1-specific siRNA or polyclonal antisera, both of which diminished CVB3-induced myocarditis. These unexpected findings indicate that increased TIMP-1 expression exacerbates, rather than ameliorates, CVB3-induced myocarditis and, thus, that TIMP-1 may represent a target for the treatment of virus-induced heart disease.  相似文献   
59.
60.

Introduction

Neurosurgery remains among the highest malpractice risk specialties. This study aimed to identify areas in neurosurgery associated with litigation, attendant causes and costs.

Methods

Retrospective analysis was conducted of 42 closed litigation cases treated by neurosurgeons at one hospital between March 2004 and March 2013. Data included clinical event, timing and reason for claim, operative course and legal outcome.

Results

Twenty-nine claims were defended out of court and twelve were settled out of court. One case required court attendance and was defended. Of the 42 claims, 28, 13 and 1 related to spinal (0.3% of caseload), cranial (0.1% of caseload) and peripheral nerve (0.07% of caseload) surgery respectively. The most common causes of claims were faulty surgical technique (43%), delayed diagnosis/misdiagnosis (17%), lack of information (14%) and delayed treatment (12%), with a likelihood of success of 39%, 29%, 17% and 20% respectively. The highest median payouts were for claims against faulty surgical technique (£230,000) and delayed diagnosis/misdiagnosis (£212,650). The mean delay between clinical event and claim was 664 days.

Conclusions

Spinal surgery carries the highest litigation risk versus cranial and peripheral nerve surgery. Claims are most commonly against faulty surgical technique and delayed diagnosis/misdiagnosis, which have the highest success rates and payouts. In spinal surgery, the most common cause of claims is faulty surgical technique. In cranial surgery, the most common cause is lack of information. Claims may occur years after the clinical event, necessitating thorough contemporaneous documentation for adequate future defence. We emphasise thorough patient consultation and meticulous surgical technique to minimise litigation in neurosurgical practice.  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