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   24097篇
  免费   1347篇
  国内免费   192篇
耳鼻咽喉   321篇
儿科学   359篇
妇产科学   465篇
基础医学   3075篇
口腔科学   495篇
临床医学   1519篇
内科学   6318篇
皮肤病学   434篇
神经病学   1708篇
特种医学   937篇
外国民族医学   1篇
外科学   4483篇
综合类   145篇
一般理论   1篇
预防医学   764篇
眼科学   263篇
药学   1458篇
中国医学   65篇
肿瘤学   2825篇
  2023年   157篇
  2022年   342篇
  2021年   557篇
  2020年   320篇
  2019年   408篇
  2018年   506篇
  2017年   404篇
  2016年   471篇
  2015年   540篇
  2014年   734篇
  2013年   798篇
  2012年   1341篇
  2011年   1485篇
  2010年   826篇
  2009年   755篇
  2008年   1272篇
  2007年   1381篇
  2006年   1388篇
  2005年   1357篇
  2004年   1375篇
  2003年   1268篇
  2002年   1236篇
  2001年   571篇
  2000年   641篇
  1999年   574篇
  1998年   307篇
  1997年   254篇
  1996年   234篇
  1995年   178篇
  1994年   145篇
  1993年   167篇
  1992年   374篇
  1991年   320篇
  1990年   345篇
  1989年   313篇
  1988年   282篇
  1987年   249篇
  1986年   218篇
  1985年   214篇
  1984年   167篇
  1983年   124篇
  1982年   67篇
  1981年   63篇
  1979年   81篇
  1978年   78篇
  1977年   87篇
  1975年   63篇
  1974年   64篇
  1972年   63篇
  1968年   65篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
The acoustic levitation method (ALM) is expected to be applied as a container-less processing technology in the material science, analytical chemistry, biomedical technology, and food science domains because this method can be used to levitate any sample in mid-air and prevent nucleation and contamination due to the container wall. However, this approach can lead to nonlinear behavior, such as acoustic streaming, which promotes the evaporation of a levitated droplet. This study aims to understand the evaporation and precipitation kinetics of an acoustically levitated multicomponent droplet. An experimental investigation of the evaporation process of a salt solution droplet was performed, and the experimental results were compared with those of the d2-law. The droplet was noted to evaporate in two stages owing to the precipitation of the salt. Because of the vapor pressure depression, the experimental data did not agree with the classical prediction obtained using the d2-law. However, the experimental results were in partial agreement with those of the d2-law when the vapor pressure depression was considered by using the concentration estimate at each time, as obtained from the experimental results. In addition, it was observed that the time when the salt completely precipitated could be estimated by using the extended theory. These findings provide physical and practical insights into the droplet evaporation mid-air for potential lab-in-a-drop applications.

The droplet levitation dynamics associated with the evaporation and precipitation facilitate a more universal understanding for potential lab-in-a-drop applications.  相似文献   
993.
A 23-year-old woman was transferred to our hospital due to exacerbating dyspnea with wheeze. After admission, we started mechanical ventilation immediately, and she was diagnosed with status asthmatics. On the following day, she was able to be weaned from the ventilator. However, she required re-intubation because of an unstable respiratory condition just after extubation. Detailed neurological investigations identified blepharoptosis and muscle weakness with easy fatigability. An edrophonium test was positive. Anti-acetylcholine receptor antibody was detected in her serum. She was finally diagnosed with myasthenia gravis and successfully treated with neostigmine and a low-dose corticosteroid.  相似文献   
994.
Thirty-five patients who died of differentiated thyroid cancer were analyzed for factors affecting survival. The neck was the most common initial site of recurrence (62.0%). The lung was the most common metastatic site (56.7%). Major sites associated with death were locoregional recurrence (neck and mediastinum: 48.6%) and bone metastases (22.9%). By univariate analysis, local tumor extension, type of initial surgery, and residual tumor and/or existence of distant metastases at the initial operation were significant factors affecting survival. Stepwise multivariate analysis revealed that invasion of the esophagus and/or carotid artery shortened survival and that multiple surgeries extended survival. Our results suggest that to improve survival in patients with differentiated thyroid cancer, better locoregional control, including multiple surgical resection, is necessary. © 1996 Wiley-Liss, Inc.  相似文献   
995.
996.
Incidence of Urolithiasis in Northeast Thailand   总被引:3,自引:0,他引:3  
Background :
Urolithiasis is a major health problem in the northeast part of Thailand. In this study, we examined the prevalence of renal stone disease and differences of urinary components between stone formers and healthy control subjects in northeastern rural areas of Thailand.
Methods :
We selected 3 villages in the rural areas of Khon Kaen province in northeast Thailand. Three hundred and sixty-seven persons were asked questions relating to urolithiasis and were examined by abdominal ultrasound (US). We collected a spot urine sample from stone formers and healthy control subjects from each village.
Results :
Abnormal findings by US were detected in 39 individuals (10.6%), and included 31 individuals with renal calculi (8.4%), 16 with hydronephrosis (4.4%), and 1 individual with a renal cyst (0.3%). This yielded a disease rate of urinary stones in this study of 16.9%. The male/female ratio was 2/1 and the average age of the individuals examined was 40.3 + 13.9 years. However, there was no significant difference between the urinary parameters of stone formers and the healthy control subjects. Conclusion: There was a high incidence of renal stone disease in the northeast part of Thailand, but the tendency for hypocitraturia was only found in stone formers.  相似文献   
997.
Background:There are various alternative first-line therapeutic options besides tyrosine kinase inhibitors (TKIs) for metastatic renal cell carcinoma (mRCC). To inform therapeutic decision-making for such patients, this study aimed to identify predictive factors for resistance to TKI.Materials and methods:A total of 239 cases of mRCC patients who received first-line TKI therapy were retrospectively studied. Patients with a radiologic diagnosis of progressive disease within 3 months after initiating therapy were classified as primary refractory cases; the others were classified as non-primary refractory cases. The association between primary refractory cases and age, gender, pathology findings, serum c-reactive protein (CRP) level, metastatic organ status, and 6 parameters defined by the International Metastatic Renal Cell Carcinoma Database Consortium were analyzed.Results:Of 239 cases, 32 (13.3%) received a radiologic diagnosis of progressive disease within 3 months after initiating therapy. The rates of sarcomatoid differentiation, hypercalcemia, a serum CRP level of 0.3 mg/dL or higher, presence of liver metastasis, anemia, and time from diagnosis to treatment interval of less than a year were significantly higher in the primary refractory group. Multivariate analysis showed that sarcomatoid differentiation, hypercalcemia, a serum CRP level of 0.3 mg/dL or higher, and liver metastasis were independently associated with primary refractory disease. A risk-stratified model based upon the number of patients with these factors indicated rates of primary refractory disease of 4.0%, 10.1%, and 45.0% for patients with 0, 1, and 2 or more factors, respectively.Conclusions:Sarcomatoid differentiation, hypercalcemia, an elevated serum CRP level, and presence of liver metastasis were associated with primary refractory disease in mRCC patients receiving first-line TKI therapy. These results provide clinicians with useful information when selecting a first-line therapeutic option for mRCC patients.  相似文献   
998.
BackgroundManagement of pacemaker (PM) infections among advanced aged patients possesses particular clinical challenges due to higher rates of concurrent cardiovascular disease and medical comorbidities. Novel leadless cardiac pacemakers (LCPs) may provide new opportunities for better management options in this population, however, there is limited data especially in Asian populations to guide the decision making.MethodsWe reviewed 11 octogenarians (median age: 86 [minimum 82–maximum 90] years; male: 73%; median body mass index (BMI): 20.1 kg/m2) who received Micra Transcatheter Pacing System (Medtronic Inc, Minneapolis, MN) implantations following transvenous lead extractions (TLEs) for PM infections. ResultsAll patients had more than two medical comorbidities (average 3.7 comorbidities). The indications for LCP implantations were atrioventricular block in four patients, atrial fibrillation bradycardia in five, and sinus node dysfunction in two. Eight patients (73%) were bridged with temporary pacing using active fixation leads (median interval of 14.0 days), while one with severe dementia underwent a concomitant LCP implantation and TLE during the same procedure. Successful TLEs and LCP implantations were successfully accomplished in all without any complications. The median time from the TLE procedure to discharge was 22 days (minimum 7–maximum 136). All patients remained free of infections during a mean follow-up period of 17.2 ± 6.5 months.ConclusionsLCP implantations were safe and effective after removing the entire infectious PM system in all octogenarians. The novel LCP technology may offer an alternative option for considering a re-implantation strategy after transvenous PM infections in elderly patients, particularly those with severe frailty and PM dependency.

The incidence of cardiac pacemaker (PM) infections among patients with an advanced age has been increasing owing to the continually widening indications and growing number of generator replacements.[13] In current clinical practice, there is a class l indication for removing all hardware in the case of a proven or suspected device infection, and after a recovery window, a new conventional PM is implanted in PM dependent patients.[1,4,5] However, this management for the elderly population is one of the most sensitive issues, since they possess particular clinical challenges due to higher rates of concurrent cardiovascular disease and medical comorbidities.[610]Recently, the implantation of a Micra Transcatheter Pacing System (Medtronic Inc, Minneapolis, MN) has emerged as a new option for PM re-implantations after the removal of infectious PMs.[1117] Without the use of leads and a device pocket, this leadless cardiac pacemaker (LCP) potentially reduces the risk of pocket infections and lead associated endocarditis.[16,17] However, there have not been enough data supporting the feasibility of leadless PM implantations following the removal of infectious PMs in people with an older age, particularly in octogenarians. Furthermore, there has been no data regarding those therapeutic strategies in Asian populations who have a low body mass index (BMI) and are at a higher risk of a transvenous lead extraction (TLE) procedure. Therefore, in this case series, we sought to characterize the procedure for LCP implantations following TLEs of infected PMs in octogenarians at 2 Japanese high-volume centers.  相似文献   
999.
Objective. To investigate the characteristics of HLA-B27 that render susceptibility to seronegative spondylarthropathies. Methods. Serologic HLA class I typing of Japanese patients with ankylosing spondylitis (AS), juvenile rheumatoid arthritis (JRA), and healthy controls, was performed. HLA-B39 subtypes were determined by polymerase chain reaction-sequence-specific oligohy-bridization. Results. HLA-B27 was present in 40 of 48 patients with AS (83%), and in only 1 of 210 healthy controls (0.5%). Three of 8 patients (37.5%) who were negative for HLA-B27 were positive for HLA-B39, which was significantly higher compared with the HLA-B27-negative controls (6.2% P = 0.01). Significant association with HLA-B39 was also noted in the JRA patients (16.7%; P < 0.01), especially in those patients with pauciarticular-onset disease (33.3%; P < 0.01). Ten of 13 HLA-B39-positive patients had subtype B*3901 and 3 had B*3902. Conclusion. Because HLA-B27 and HLA-B39 share Glu at position 45 and Cys at position 67, both of which constitute components of the peptide-anchoring B pocket, and because they possess similar peptide-ligand motifs, our results may support either the role of the peptides presented by class I antigens or the importance of Cys at position 67, in the development of spondylarthropathies and pauciarticular-onset JRA.  相似文献   
1000.
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