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   30242篇
  免费   1404篇
  国内免费   226篇
耳鼻咽喉   216篇
儿科学   717篇
妇产科学   303篇
基础医学   3842篇
口腔科学   620篇
临床医学   1901篇
内科学   8317篇
皮肤病学   440篇
神经病学   1955篇
特种医学   1168篇
外科学   5329篇
综合类   117篇
预防医学   741篇
眼科学   417篇
药学   1945篇
中国医学   48篇
肿瘤学   3796篇
  2023年   215篇
  2022年   421篇
  2021年   717篇
  2020年   366篇
  2019年   582篇
  2018年   710篇
  2017年   546篇
  2016年   702篇
  2015年   718篇
  2014年   981篇
  2013年   1128篇
  2012年   1804篇
  2011年   2014篇
  2010年   1122篇
  2009年   959篇
  2008年   1677篇
  2007年   1885篇
  2006年   1819篇
  2005年   1862篇
  2004年   1795篇
  2003年   1717篇
  2002年   1695篇
  2001年   535篇
  2000年   436篇
  1999年   469篇
  1998年   422篇
  1997年   336篇
  1996年   329篇
  1995年   263篇
  1994年   244篇
  1993年   233篇
  1992年   356篇
  1991年   322篇
  1990年   291篇
  1989年   282篇
  1988年   235篇
  1987年   199篇
  1986年   208篇
  1985年   155篇
  1984年   132篇
  1983年   121篇
  1982年   87篇
  1981年   55篇
  1979年   73篇
  1978年   68篇
  1977年   58篇
  1975年   50篇
  1974年   58篇
  1973年   55篇
  1972年   52篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
We report the first case of early-onset Parkinson's disease (EOP) with the PTEN-induced kinase 1 (PINK1) gene deletion in 62 years old Japanese female. The symptoms were started with unstable gait at the age 38. Parkinsonian symptoms became apparent in 45 years old. L-Dopa was markedly effective on her parkinsonian symptoms. However, equinovarus foot induced by L-Dopa intake appeared three months prior to the admission. On admission, she presented with mild cognitive impairment, severe depression, marked retropulsion, resting tremor in the left upper limb and mild hyperreflexia in the four limbs. Rigidity was not present. Mutational analysis revealed homozygous deletion from exon 6 to 8 in the PINK1 gene. An ethnic diversity in PINK1 mutation is suggested.  相似文献   
992.
Approximately 90% of infants congenitally infected with cytomegalovirus are asymptomatic at birth, but a number of them later develop central nervous system disorders. However, diagnosis of congenital infection with virologic or serologic evidence had been almost impossible beyond the neonatal period. Recently, dried blood spots on Guthrie cards have been demonstrated to be useful for retrospective diagnosis of congenital cytomegalovirus infection; however, they are usually stored for only 1 year. In Japan, the umbilical cord is kept clean and dry as a symbol of the mother-to-child bond, and in recent studies, cytomegalovirus deoxyribonucleic acid was successfully detected from dried umbilical cord of two 1-year-old children who were clinically suspected of having had congenital cytomegalovirus infection. This report describes a 4-year-old male with various central nervous system disorders who was diagnosed with congenital cytomegalovirus infection by detecting cytomegalovirus deoxyribonucleic acid from dried umbilical cord.  相似文献   
993.

Objective

This Phase 2 study assessed the performance of positron emission tomography (PET) brain images made with Flutemetamol F 18 Injection in detecting β-amyloid neuritic plaques in Japanese subjects.

Methods

Seventy subjects (25 with probable Alzheimer’s disease (pAD), 20 with amnestic mild cognitive impairment (aMCI), and 25 cognitively normal healthy volunteers[HVs]) underwent PET brain imaging after intravenous Flutemetamol F 18 Injection (185 MBq). Images were interpreted as normal or abnormal for neuritic plaque density by each of five non-Japanese and five Japanese readers who were blinded to clinical data. The primary efficacy analysis (based on HV and pAD data) was the agreement of the non-Japanese readers’ image interpretations with the clinical diagnosis, resulting in estimates of positive percent agreement (PPA; based on AD subjects; similar to sensitivity) and negative percent agreement (NPA; based on HVs; similar to specificity). Secondary analyses included PPA and NPA for the Japanese readers; inter-reader agreement (IRA); intra-reader reproducibility (IRR); quantitative image interpretations (standardized uptake value ratios [SUVRs]) by diagnostic subgroup; test–retest variability in five pAD subjects; and safety.

Results

PPA was 92% for all non-Japanese readers and ranged from 88 to 92% for the Japanese readers. NPA ranged from 96 to 100% for both the non-Japanese readers and the Japanese readers. The majority image interpretations (the interpretations made independently by ≥3 of 5 readers) resulted in PPA values of 92 and 92% and NPA values of 100 and 96% for the non-Japanese and Japanese readers, respectively. IRA and IRR were strong. Composite SUVR values (mean of multiple regional values) allowed clear differentiation between pAD subjects and HVs. Test–retest variability ranged from 1.14 to 2.27%, and test–retest agreement of the blinded visual interpretations was 100% for all readers. Flutemetamol F 18 Injection was generally well tolerated.

Conclusions

The detection of brain neuritic plaques in Japanese subjects using [18F]Flutemetamol PET images gave results highly consistent with clinical diagnosis, with non-Japanese and Japanese readers giving similar results. Inter-reader agreement and intra-reader reproducibility were high for both sets of readers. Visual delineation of abnormal and normal scans was corroborated by quantitative assessment, with low test–retest variability.

Trial registration

Clinicaltrials.gov registration number NCT02813070.
  相似文献   
994.
Abstract: A 78-year-old male with renal carcinoma was treated with a high dose infusion of interferon-alpha (IFN-alpha) for eight months. The patient had evidence of organlc brain syndrome such 88 : dysfunction of memory, slowing of behavior, and development of mental confusion that appeared eight months after the treatment. MRI at the time of mental confusion revealed difise white matter lesions. Neuropathologic findings were compatible to Binswanger's disease and Senile Dementia of Alzheimer Type (SDAT), Preexisting neurologic abnormalities including intracerebral arteriosclerosis and cerebral atrophy may increase susceptibility to unacceptably severe IFN neurotoxicity.  相似文献   
995.

Objective

Antipsychotic dose reduction is generally recommended to occur after six months of clinical stabilization despite inadequate evidence. This timing issue was addressed in this study.

Methods

This is an observational, retrospective and medical chart-based study. Inclusion criteria were (1) diagnosis of schizophrenia (DSM-IV), (2) being acutely psychotic at their first outpatient visit from May, 2002 to April, 2003, (3) having responded to antipsychotics and achieved clinical stabilization of acute symptoms, indexed as a fixation of regimen for four or more weeks, and (4) having one or more years of follow-up. Patients who had their antipsychotic doses reduced were then identified, and they were divided into two groups based on the waiting period before dose reduction: <24 weeks (Early Group) and ≥24 weeks (Standard Group). The rate of dose escalation for ≥20% during follow-up period was investigated as a proxy of clinical worsening.

Results

After excluding stable patients at baseline, 211 patients met inclusion criteria. The mean ± SD waiting period before reducing antipsychotics was 122 ± 102 days. The rates of patients needing dose escalation were not significantly different between patients whose dose was reduced (N = 83) and those who was not (N = 128) (57.8% vs. 59.4%), and between Early Group (N = 59) and Standard Group (N = 24) (61.0% vs. 50.0%) although the reduction rate in antipsychotic dosage was significantly greater in Early Group (58.7% vs. 43.3%, p < 0.05).

Conclusion

These findings may indicate that timeline until antipsychotic reduction in stable patients with schizophrenia could be earlier than recommended, although caution is needed in interpreting our retrospective results.  相似文献   
996.
Hepatic abscess in chronic granulomatous disease (CGD) is very refractory and frequently requires multiple surgeries with frequent morbidities. Although surgical interventions are often required, patients are often not able to have surgery for various reasons. We present the case of a 21-year-old man with recurrent hepatic abscess in CGD. We could not provide surgical interventions due to the lack of a fluid cavity and the patient's refusal, and therefore we administered transcatheter arterial antimicrobial and steroid therapy. He did not have any exacerbation for more than 18 months after the final transcatheter treatment. This is the first reported case of successful transcatheter arterial antimicrobial and steroid therapy for refractory hepatic abscess in CGD. Although the patient's burden and medical cost were not inconsequential, this case shows that the transcatheter arterial antimicrobial and steroid therapy may be a treatment option for patients who are not candidates for surgical interventions.  相似文献   
997.
We conducted a nationwide molecular epidemiological study of Clostridium difficile infection (CDI) in Japan investigated the correlation between the presence of binary toxin genes and CDI severity. This is the first report on molecular epidemiological analyses for CDI in multiple university hospitals in Japan, to our knowledge. We examined 124,484 hospitalized patients in 25 national and public university hospitals in Japan between December 2013 and March 2014, investigating antimicrobial susceptibilities and toxin-related genes for C. difficile isolates from stools. Epidemiological genetic typing was performed by PCR-ribotyping and repetitive sequence-based (rep)-PCR to examine the genetic similarities. The results detected toxin A-positive, toxin B-positive, binary toxin-negative (A+B+CDT?) detected from 135 isolates (80.8%) and toxin A-negative, toxin B-positive, binary toxin-negative (A??B+CDT?) in 23 (13.8%). Toxin A-positive, toxin B-positive, and binary toxin-positive (A+B+CDT+) were seen in 9 isolates (5.4%). Vancomycin (n = 81, 37.7%) or metronidazole (n = 88, 40.9%) therapies were undertaken in analyzed cases. Ribotypes detected from isolates were 017/subgroup 1, 070, 078, 126, 176, 449, 475/subgroup 1, 499, 451, 566 and newtypes. Rep-PCR classified 167 isolates into 28 cluster groups including 2–15 isolates. In addition, 2 pairs of strains isolated from different institutions belonged to the same clusters. Seven out of 9 (77.8%) of the patients with binary toxin producing strains had “mild to moderate” outcome in evaluated symptoms. In conclusion, we found that binary toxin did not show regional specificity and had no relevance to severity of CDI.  相似文献   
998.
Recently, exercise-induced spastic coronary artery occlusion at the site of moderate stenosis, which Prinzmetal’s angina or cardiac syndrome X does not cover, was reported. Multi-modality imaging is important for the diagnosis of coronary artery disease with a complex ischemic mechanism. However, the previous report did not include findings from intracoronary imaging at the site of moderate coronary stenosis. We report a case of exercise-induced vasospastic angina at the site of moderate stenosis, where multi-modality imaging, including exercise stress echocardiography and intravascular ultrasound, was utilized to make a definitive diagnosis and investigate underlying causes.  相似文献   
999.
1000.
Alghough gaseous ammonia (NH3) can freely enter cells through the plasma membrane where NH3 is cyto(neuro)toxic, NH3 and ionic ammonia (NH4 +) contents have not been studied in biological materials. We developed a new method for measurement of expiratory NH3 concentration, which may reflect blood NH3 concentrations. The method is a sensor tube type-gas assay system. Expiratory NH3 concentrations in patients with chronic liver diseases increased when their blood ammonia (NH4 ++NH3) concentrations increased above 90 μg/dl (normal range; 12–66 μg/dl). However, cirrhotic patients, who had relatively higher expiratory NH3 concentration compared to blood NH3 concentrations (calculated from Henderson-Hasselbalch formula), were found to have subclinical encephalopathy. Measurement of experatory NH3 concentration may be of clinical significance for the diagnosis of encephalopathy associated with hyperammonemia.  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