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   2386篇
  免费   108篇
  国内免费   27篇
耳鼻咽喉   22篇
儿科学   22篇
妇产科学   44篇
基础医学   281篇
口腔科学   68篇
临床医学   169篇
内科学   535篇
皮肤病学   11篇
神经病学   131篇
特种医学   153篇
外科学   459篇
综合类   5篇
预防医学   126篇
眼科学   54篇
药学   163篇
肿瘤学   278篇
  2023年   32篇
  2022年   61篇
  2021年   86篇
  2020年   40篇
  2019年   71篇
  2018年   71篇
  2017年   44篇
  2016年   62篇
  2015年   69篇
  2014年   57篇
  2013年   102篇
  2012年   129篇
  2011年   146篇
  2010年   62篇
  2009年   65篇
  2008年   124篇
  2007年   121篇
  2006年   105篇
  2005年   130篇
  2004年   86篇
  2003年   124篇
  2002年   120篇
  2001年   56篇
  2000年   66篇
  1999年   62篇
  1998年   24篇
  1997年   14篇
  1996年   22篇
  1995年   18篇
  1994年   10篇
  1993年   14篇
  1992年   30篇
  1991年   29篇
  1990年   36篇
  1989年   30篇
  1988年   34篇
  1987年   26篇
  1986年   19篇
  1985年   13篇
  1984年   10篇
  1983年   10篇
  1981年   8篇
  1980年   8篇
  1979年   11篇
  1977年   9篇
  1974年   6篇
  1972年   4篇
  1969年   6篇
  1968年   5篇
  1966年   11篇
排序方式: 共有2521条查询结果,搜索用时 15 毫秒
91.
ObjectivesSialolipoma has been classified as a benign soft tissue lesion in the 2017 World Health Organization classification of head and neck tumors. To our knowledge, only one case of laryngeal sialolipoma has been reported in the English literature. We conducted a retrospective study to identify clinical characteristics of supraglottic sialolipoma-like lesion and differentiate it from other supraglottic subepithelial masses.MethodsMedical records of 16 patients with supraglottic subepithelial benign mass lesions who underwent histological evaluation between 2003 and 2019 were retrospectively analyzed. Sialolipoma-like lesion was defined as a local finding of a well-circumscribed gross mass with pathological presence of salivary gland-like parenchymal lobules with evenly interspersed adipose tissue.ResultsEight patients showed histological positivity for sialolipoma-like lesion, 3 for amyloidosis, 2 for hemangioma, and 1 each for cyst, lymphoid hyperplasia, and chondrometaplasia. Sialolipoma-like lesion tended to be predominant among men; those affected had a mean age of 52.8 (range, 39–74) years. By contrast, among patients with amyloidosis, the ratio of men to women was 1:2 (100% vs. 33%; p = 0.055). Fiberscopic examination of all patients with sialolipoma-like lesions identified well-circumscribed, yellowish masses, closely resembling local amyloidosis findings. Sialolipoma-like lesion was associated with a significantly higher body-mass index (BMI; 27.4 ± 2.8 kg/m2) than amyloidosis (21.6 ± 1.4 kg/m2; p = 0.014). The transoral approach was used for lesion resection in all patients with sialolipoma-like lesion. No patient experienced postoperative recurrence.ConclusionLaryngeal sialolipoma-like lesion might be more prevalent than was previously reported, and histological examination is important to differentiate it from amyloidosis. Supraglottic sialolipoma-like lesion must be differentially diagnosed in patients with high BMI presenting with well-circumscribed, yellowish supraglottic masses.  相似文献   
92.
Heart transplantation started in Japan in 1999. Since then, 50 transplants have been performed at our center. We performed histopathological analyses of the 50 explanted hearts and the post‐transplant biopsy specimens. The median age of recipients was 39 years. The primary diseases before transplant were idiopathic dilated cardiomyopathy in 33 patients (66%), hypertrophic cardiomyopathy in seven (14%), restrictive cardiomyopathy in one, arrhythmogenic right ventricular cardiomyopathy in one, and secondary cardiomyopathy in eight (16%). Before transplantation, 47 patients (94%) had left ventricular assist devices. No severe cardiovascular failure due to allograft rejection occurred. The post‐transplant survival rate was 97.6% at 1 year and 93.1% at 10 years. One recipient was lost to sepsis from myelodysplastic syndrome in the fourth year, one died of multiple organ failure and peritonitis 8 months after transplant. Another patient died of recurrent post‐transplant lymphoproliferative disorders (PTLD). Mild cardiac dysfunction occurred in seven recipients in the early postoperative period. Moderate acute cellular rejection occurred in six patients (12%), and antibody‐mediated rejection occurred in three (6%). The number of heart transplants performed in Japan is very small. However, the outstanding 10‐year survival rate is due to donor evaluation and post‐transplant care resulting in low grade rejection. Pathological evaluation has also greatly contributed to the results.  相似文献   
93.
Ventricular assist devices (VADs) have long been used as bridge to transplant therapy (BTT). Nipro-Toyobo paracorporeal pulsatile-flow VAD (nt-VAD) was the only device available until April 2011, when implantable continuous-flow VADs (cf-VADs) became available. Although cf-VADs are central to BTT, nt-VAD remains a necessary option. We aimed to clarify the role of nt-VAD in an era of increasing cf-VAD use. We retrospectively reviewed patients who underwent VAD implantation at the National Cerebral and Cardiovascular Center from May 2011 to March 2013. Characteristics were compared between the nt-VAD and cf-VAD groups. Twenty-nine patients (mean age 37.7 ± 11.1 years, 23 males) underwent VAD implantation. Fifteen patients initially received nt-VADs, although 4 were converted to cf-VADs. Of these 15 patients, 3 were too small for cf-VADs and 2 needed bilateral ventricular support. The remaining 10 patients received nt-VADs (7 patients at INTERMACS level 1 and 3 at level 2). The nt-VAD group patients had significantly more preoperative mechanical circulatory support and were in a more critical condition before VAD implantation than the cf-VAD group. The 2-year survival rate was not significantly different. Despite the critical conditions of nt-VAD patients, their overall survival is not statistically inferior to that of cf-VAD patients. nt-VAD is a good option as a BTC for the patient with urgent and critical condition.  相似文献   
94.
Despite continual improvements in ventricular assist device (VAD) therapy, various clinical issues are emerging. Importantly, various types of thromboembolic complications have been reported to date. Recently, we encountered a rare continuous-flow VAD-related thromboembolic event that resulted in acute myocardial infarction. A 26-year-old female who just underwent HeartMate II® VAD implantation suddenly developed widespread anterolateral myocardial infarction on postoperative day 16. Echocardiography and aortography revealed a large thrombus on the left coronary cusp of the aortic valve that almost completely occluded the left coronary ostium. After VAD implantation, her aortic valve did not open, even at relatively low pump speeds; this was thought to be one of the causes for thrombus formation. Continuous suction of blood from the left ventricle and non-pulsatile flow into the ascending aorta resulted in a continuously closed aortic valve and stagnation of blood in the coronary cusp. Furthermore, both small body size (body surface area <1.3 m2) and postoperative right ventricular failure may have exacerbated blood stagnation and thrombus formation in this patient. We should have adjusted the anticoagulation and antiplatelet therapy protocols based on the patient’s condition. She underwent off-pump coronary artery bypass surgery and remained in clinically stable condition afterwards.  相似文献   
95.
The algorithm for the physiological control provided by left ventricular assist devices (LVADs) has been controversial. In particular, little is known about the physiological control algorithm (such as for achieving physiological circadian rhythms) in continuous-flow LVADs. To investigate the existence of circadian variation, we retrospectively evaluated the LVAD flow-correlated motor current of patients supported by continuous-flow LVADs. The motor current and the pump speed were collected from the external controller every 10 min after device implantation, and the data were divided for every 30-day period, which began on midnight on the first post-operative day. The subjects were 18 patients (mean age 37.7, mean body surface area 1.71 m2 at the time of operation) with dilated cardiomyopathy or dilated phase of hypertrophic cardiomyopathy. As of August 1, 2013, the patients’ median support duration was 889 days. The mean calculated dominant period of motor current variation was 24.0 h and the mean amplitude was 11.7 mA for the entire duration. The amplitude of the motor current circadian variation tended to be increased until around the fifth month. The motor current had a tendency to be relatively low during the night time and high during the day time. A significant difference was found between the night-time and day-time mean motor current for the entire duration (p < 0.05). In conclusion, the circadian variation of the motor current could be observed over long term in patients with fixed rotation speed continuous-flow LVAD support.  相似文献   
96.
Nanofiber vascular grafts have been shown to create neovessels made of autologous tissue, by in vivo scaffold biodegradation over time. However, many studies on graft materials and biodegradation have been conducted in vitro or in small animal models, instead of large animal models, which demonstrate different degradation profiles. In this study, we compared the degradation profiles of nanofiber vascular grafts in a rat model and a sheep model, while controlling for the type of graft material, the duration of implantation, fabrication method, type of circulation (arterial/venous), and type of surgery (interposition graft). We found that there was significantly less remaining scaffold (i.e., faster degradation) in nanofiber vascular grafts implanted in the sheep model compared with the rat model, in both the arterial and the venous circulations, at 6 months postimplantation. In addition, there was more extracellular matrix deposition, more elastin formation, more mature collagen, and no calcification in the sheep model compared with the rat model. In conclusion, studies comparing degradation of vascular grafts in large and small animal models remain limited. For clinical translation of nanofiber vascular grafts, it is important to understand these differences.  相似文献   
97.
Known breast-cancer risk factors account for only part of the variability in breast-cancer incidence. Tobacco smoke is not commonly considered a breast carcinogen, but many of its constituents, such as N-nitrosamines, are carcinogenic in laboratory animal studies. Herein, we assessed a cytochrome P4502E1 (CYP2E1) genetic polymorphism (a Dral restriction enzyme site in intron 6) as a risk factor for breast cancer in both premenopausal and postmenopausal women. Because N-nitrosamines are metabolically activated by CYP2E1, the risk among women smokers was investigated. Caucasian women were enrolled in a case-control study of breast cancer between 1986 and 1991. A subset of the women (219 premenopausal and 387 postmenopausal women) consented to phlebotomy. The allelic frequencies for the premenopausal women (D allele = 0.91 and C allele = 0.09) and postmenopausal women (D allele = 0.93 and C allele = 0.07) were similar to those previously reported. There was no statistically significant association between the CYP2E1 polymorphism and breast-cancer risk for premenopausal or postmenopausal women (adjusted odds ratio (OR) = 1.04, 95% confidence interval (CI) = 0.48, 2.24, and OR = 1.01, 95% CI = 0.55, 1.84, respectively). When the women were categorized as nonsmokers versus smokers (those who smoked more than one cigarette per week for more than 1 yr), premenopausal women with one or two C alleles who had a history of smoking were found to be at increased risk (unadjusted OR = 7.00, 95% CI = 0.75, 14.53, and adjusted OR = 11.09, 95% CI = 1.51, 81.41), although the number of study subjects with those genotypes was small. The small number of study subjects with a C allele precluded meaningful classification by level of smoking, but categorizing the smokers into two groups (above and below the median) also suggested an increased risk. Premenopausal women with the DD genotype and postmenopausal women with any genotype were not at increased risk. Breast-cancer risk was not related to the CYP2E1 genotype in either premenopausal nonsmokers or smokers (adjusted OR = 0.66, 95% CI = 0.20, 2.17, and OR = 2.13, 95% CI = 0.60, 7.59, respectively) or postmenopausal nonsmokers or smokers (OR = 0.90, 95% CI = 0.34, 2.35, and OR = 1.02, 95% CI = 0.46, 2.23, respectively), although the difference in the ORs for premenopausal nonsmokers and smokers suggests an increased risk for smokers. While there are limitations to this study, particularly related to the small number of subjects with the DC and CC genotypes, the study suggests that some women may be susceptible to tobacco smoke because of a CYP2E1 polymorphism. However, these results are preliminary and must be replicated. © 1996 Wiley-Liss, Inc.
  • 1 This article is a US Government work and, as such, is in the public domain in the United States of America.
  •   相似文献   
    98.
    Abstract

    Background: Subglottic cancer (SGC) is extremely rare, as most laryngeal cancers are localized to the glottic region. Accordingly, the clinical characteristics of SGC have not been well characterized.

    Objectives: In the current study, SGCs were clinically evaluated, and the outcomes of radiotherapy (RT) in patients with stage II SGC were assessed.

    Materials and Methods: Medical data derived from 11 patients with SGC, who were treated at our hospital between 1995 and 2019, were retrospectively reviewed.

    Results: In our department SGC accounted for 3.9% of the 280 laryngeal cancer patients treated during the study period. At the time of SGC diagnosis, 9 (81.8%) had stage II cancer, 1 had stage III cancer, and 1 had stage IV cancer. Stage II SGC patients treated with concurrent chemoradiotherapy (CCRT) showed a significantly higher local control rate (p?=?.026) and laryngeal dysfunction free rate (p?=?.026) than those treated with RT alone. Salvage surgery, performed in 4 patients whose disease was not locally controlled with CCRT/RT, was successful in 3 patients.

    Conclusion: As a treatment strategy for stage II SGC, CCRT is an acceptable initial treatment for laryngeal function and preservation while salvage surgery is effective for recurrence after CCRT/RT treatment.  相似文献   
    99.
    Integrins are transmembrane proteins that mediate cell adhesion to the extracellular matrix. Integrin α11 (ITGA11) is not expressed in normal alveolar epithelial cells and is a known receptor for collagen. While integrin α11β1 overexpression in the tumor stroma has been associated with tumor growth and metastatic potential of non–small cell lung cancer (NSCLC), little is known about the role of ITGA11 in tumor cells. Thus, we examined the RNA expression of ITGA11 by quantitative RT‐PCR in 80 samples collected from NSCLC patients who had undergone surgical resection and analyzed the clinical outcomes. We found that high expression of ITGA11 was associated with lower recurrence‐free survival in all NSCLC patients (P = 0.043) and in stage I NSCLC patients (P = 0.049). These results were consistent with in silico analyses of the Cancer Genome Atlas database. We also analyzed cell proliferation, migration and invasion capacity in lung cancer cell lines after overexpression of ITGA11. Overexpression of ITGA11 in lung cancer cell lines had little effect on cell proliferation but resulted in increased migration and invasion capacity. Our findings suggest that ITGA11 plays a significant role in cancer migration and invasion, leading to higher recurrence. ITGA11 expression may be a predictor of poor prognosis in patients with surgically resected NSCLC.  相似文献   
    100.
    Background: p16INK4a (p16) expression in tongue cancer (TC) is reportedly not associated with human papilloma virus (HPV). Mutations of KRAS in cancer cells are most frequently observed within codon 12. However, few reports have investigated the association between KRAS mutations and p16 status in TC.

    Objectives: This study aimed to evaluate the influence of KRAS mutations on TC.

    Methods: Clinical records and surgically resected specimens of 85?TC patients were analyzed. Tumor samples were analyzed for mutations of KRAS located within codons 12 and 13. p16 staining was performed and considered positive in cases with moderate to strong nuclear and cytoplasmic staining.

    Results: Positive p16 staining was observed in 10 cases (11.8%). A KRAS mutation was detected in one case (1.2%). The case with KRAS mutation showed negative p16 staining. Despite being at an early stage, the patient died of lung metastasis at 43 months from initial treatment.

    Conclusions and Significance: KRAS mutations are not associated with p16 expression in TC and may predict poor prognosis in TC patients. Further analysis of mutations in regions other than codons 12 and 13 of KRAS will be necessary to determine the relationship between KRAS mutations and prognosis of this disease.  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