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   643篇
  免费   27篇
  国内免费   17篇
耳鼻咽喉   13篇
儿科学   35篇
妇产科学   22篇
基础医学   54篇
口腔科学   1篇
临床医学   72篇
内科学   109篇
皮肤病学   10篇
神经病学   34篇
特种医学   5篇
外科学   109篇
综合类   29篇
预防医学   31篇
眼科学   10篇
药学   82篇
中国医学   2篇
肿瘤学   69篇
  2022年   10篇
  2021年   11篇
  2020年   11篇
  2019年   7篇
  2018年   16篇
  2017年   3篇
  2016年   9篇
  2015年   9篇
  2014年   18篇
  2013年   29篇
  2012年   52篇
  2011年   47篇
  2010年   26篇
  2009年   21篇
  2008年   39篇
  2007年   29篇
  2006年   27篇
  2005年   23篇
  2004年   29篇
  2003年   38篇
  2002年   33篇
  2001年   23篇
  2000年   16篇
  1999年   24篇
  1998年   7篇
  1997年   4篇
  1996年   6篇
  1995年   4篇
  1991年   10篇
  1990年   3篇
  1989年   6篇
  1988年   5篇
  1987年   6篇
  1986年   5篇
  1985年   14篇
  1984年   11篇
  1983年   4篇
  1982年   4篇
  1980年   3篇
  1978年   5篇
  1977年   5篇
  1975年   3篇
  1974年   2篇
  1973年   6篇
  1972年   2篇
  1970年   2篇
  1969年   2篇
  1968年   2篇
  1967年   3篇
  1966年   2篇
排序方式: 共有687条查询结果,搜索用时 15 毫秒
51.
Resistance to chemotherapy is one of the major problems in treatment responses of lung cancer. This study explored the mechanism underlying the arsenic resistance of lung cancer. Four lung cancer cells with different proliferation activity were characterized for cytotoxicity, arsenic influx/efflux, and arsenic effects on intracellular glutathione and 8-hydroxy-2′-deoxyguanosine (8-OHdG) production. Our data revealed that relative proliferation potency of these cells was H1299 > A549 > CL3 > H1355. Moreover, A549, H1299, and H1355 were markedly resistant to As2O3 with IC50  100 μM, whereas CL3 was sensitive to As2O3 with IC50  11.8 μM. After treatment with the respective As2O3 at IC50, arsenic influx/efflux activity in CL3 was comparable to those in the other three arsenic-resistant cells. However, differences in glutathione levels and 8-OHdG production were also detected either before or after arsenic treatment, indicating that a certain degree of variation in anti-oxidative systems and/or 8-OHdG repair activity existed in these cell lines. By transfection of an aquaglyceroporin 9 (AQP9) gene, we showed that increased AQP9 expression significantly enhanced arsenic uptake and disrupted arsenic resistance of A549. The present study strongly suggests that membrane transporters responsible for arsenic uptake, such as AQP9, may play a critical role in development of arsenic resistance in human lung cancer cells.  相似文献   
52.
53.
Central retinal vein occlusion and intracerebral hemorrhage are rare diseases during infancy and are both related to venous thrombosis. We present the case of a full-term male hydrops infant without specific neurologic symptoms initially but later demonstrating bilateral central retinal vein occlusion and intracerebral hemorrhage. We conclude that routine funduscopic examination in high-risk newborns should be seriously considered.  相似文献   
54.
UVB irradiation is known to produce DNA damage at mutation hotspots in the p53 tumor suppressor gene, leading to the development of skin cancers. Mutations in the PTCH tumor suppressor gene, which is known to be responsible for the development of nevoid basal cell carcinoma syndrome, have also been identified in sporadic basal cell carcinomas (BCCs). We describe the case of an 80-year-old welder in whom 3 novel p53 mutations, as well as UV-specific PTCH mutations, were detected in two BCC samples from sun-exposed skin. The simultaneous presence of UV-specific p53 and PTCH mutations in the same BCC sample has not previously been reported.  相似文献   
55.
Chao SC  Lee HT  Kao TH  Yang MY  Tsuei YS  Shen CC  Tsou HK 《Surgical neurology》2008,70(1):59-65; discussion 65
BACKGROUND: Previous reports of the efficacy of percutaneous pulsed radiofrequency have been confounded by fewer case numbers, poor patient selection, and limited data on cervical or lumbar radicular pain. We used percutaneous pulsed radiofrequency for cervical and lumbar radicular pain, and the study has more than 100 cases for the analysis of the efficacy of percutaneous pulsed radiofrequency. METHODS: We collected 154 cases of patients with lumbar or cervical radicular pain due to a herniated intervertebral disk or previous failed surgery. They underwent pulsed radiofrequency therapy in 2 to 4 spinal levels unilaterally. Follow-up period was from 1 week to 1 year postoperatively. RESULTS: Twenty-six (53.06%) of 49 patients and 59 (50.86%) of 116 patients after cervical and lumbar pulsed radiofrequency stimulation, respectively, had an initial improvement of 50% or more in the first week of follow-up. Twenty-seven (55.10%) of 49 patients and 52 (44.83%) of 116 patients after cervical and lumbar pulsed radiofrequency stimulation, respectively, had pain relief of 50% or more at the follow-up period of 3 months. In the analysis of patients with pain relief of 50% or more for at least 1 month, the most effective period was during postoperation 1 month later. No complication was found among these patients. CONCLUSIONS: The results of this retrospective analysis showed that the application of pulsed radiofrequency is a safe and useful intervention for cervical and lumbar radicular pain. The satisfactory pain relief obtained by most of our patients justifies the start of this study for at least 6 months. Although pulsed radiofrequency appears to provide intermediate-term relief of pain, further studies with long-term follow-up are necessary.  相似文献   
56.
For evaluation of the clinical application of immunoassay for nuclear matrix protein 22 (NMP22 immunoassay) and urinary cytology for early diagnosis and detection of bladder cancer in patients with hematuria and/or a previous history of bladder cancer, 209 urine samples obtained from 137 patients presenting episodes of hematuria or a history of bladder cancer were assayed for NMP22 levels and/or prepared for cytology examination. Biopsy was performed when any visible tumor was identified during cystoscopy examination. The median NMP22 concentrations measured in samples taken from patients with active bladder cancer, from patients with a history of bladder cancer but no active disease, from patients with hematuria, and from healthy volunteers were 18.95, 5.45, 6.39, and 3.75 U/ml, respectively. The urinary NMP22 level recorded for patients with urothelial carcinoma was significantly higher than that noted for individuals without active disease. The sensitivity of the NMP22 assay and of urinary cytology in diagnosing bladder cancer was 69% and 67%, respectively. In contrast, the specificity of these two diagnostic modalities reached 72% and 93%, respectively. The NMP22 assay is slightly more sensitive but less specific than urinary cytology in detecting bladder cancer. This study indicates that determination of urinary NMP22 levels is a useful and noninvasive tool for the detection of bladder cancer because of its high sensitivity. The urinary NMP22 assay may be used as a first-line routine screening method; however, it cannot replace the use of urinary cytology because of its lower specificity.  相似文献   
57.
58.
59.
Intercostal nerve block is a widely used and effective approach to providing regional anesthesia in the thoracic region for pain relief. However, during ultrasound-guided intercostal nerve block, inaccurate identification of the anatomic structures or suboptimal positioning of the needle tip may result in complications and blockade failure. In this study, we designed an intraneedle ultrasound (INUS) system and validated its efficacy in identifying anatomic structures relevant to thoracic region anesthesia. The 20-MHz INUS transducer comprised a single lead magnesium niobate–lead titanate crystal, and gain was set to 20 dB. It fit into a regular 18G needle and emitted radiofrequency-mode ultrasound signals at 1 mm from the needle tip. One hundred intercostal punctures were performed in 10 piglets. Intercostal spaces were identified by surface ultrasound or palpation and located by inserting and advancing the INUS transducer needle until the appropriate anatomy was identified. Blockade success was defined by ideal saline and dye spreading and confirmed by dissection. The pleura had a distinctive ultrasound signal, and successful detection of the intercostal muscles, endothoracic fascia and double-layered parietal and visceral pleura was achieved in all 100 puncture attempts. INUS allows real-time identification of intercostal structures and facilitates successful intercostal nerve blocks.  相似文献   
60.
Self‐management helps patients understand their illnesses and learn about disease‐related skills so they can better manage their situation. However, published studies on the effectiveness of self‐management for chronic obstructive pulmonary disease (COPD) are heterogeneous. Quasi‐experimental design was used to investigate the effectiveness of a self‐management program in self‐care efficacy and quality of life in patients with COPD. Sixty participants who had experienced COPD were assigned to control group (usual care) or experimental group (self‐care program) (1:1 ratio) according to a purposeful sampling at a Medical Center in Taiwan. The Medical Research Council dyspnea scale, the COPD Self‐Efficacy Scale, the Clinical COPD Questionnaire were used to analyze data. The Medical Research Council dyspnea scale was more significant improvement in the 2 months after discharge in the experimental group than in the control group. The COPD Self‐Efficacy Scale and Clinical COPD Questionnaire scores in the experimental group within 3 months after discharge were significantly improved compared with the control group. These findings demonstrate the application and initial effect of this self‐management program.  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