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   1385篇
  免费   84篇
  国内免费   10篇
耳鼻咽喉   8篇
儿科学   39篇
妇产科学   4篇
基础医学   148篇
口腔科学   23篇
临床医学   100篇
内科学   301篇
皮肤病学   37篇
神经病学   190篇
特种医学   73篇
外科学   211篇
综合类   9篇
预防医学   53篇
眼科学   3篇
药学   74篇
中国医学   1篇
肿瘤学   205篇
  2023年   22篇
  2022年   38篇
  2021年   65篇
  2020年   27篇
  2019年   33篇
  2018年   54篇
  2017年   40篇
  2016年   48篇
  2015年   37篇
  2014年   48篇
  2013年   56篇
  2012年   86篇
  2011年   93篇
  2010年   42篇
  2009年   37篇
  2008年   72篇
  2007年   62篇
  2006年   86篇
  2005年   67篇
  2004年   56篇
  2003年   59篇
  2002年   65篇
  2001年   21篇
  2000年   17篇
  1999年   24篇
  1998年   9篇
  1997年   9篇
  1996年   21篇
  1995年   13篇
  1994年   7篇
  1993年   13篇
  1992年   23篇
  1991年   20篇
  1990年   12篇
  1989年   10篇
  1988年   17篇
  1987年   14篇
  1986年   14篇
  1985年   7篇
  1984年   3篇
  1983年   4篇
  1982年   2篇
  1979年   3篇
  1978年   3篇
  1972年   3篇
  1971年   2篇
  1967年   4篇
  1965年   1篇
  1935年   1篇
  1912年   1篇
排序方式: 共有1479条查询结果,搜索用时 15 毫秒
11.
The purpose of this study was to describe the results of definitive radiotherapy (RT) with concurrent chemotherapy for maxillary sinus carcinomas (MSCs) with neck lymph node metastasis to clarify its limitation. Local control (LC), progression-free survival (PFS) and overall survival (OS) rates were calculated using the Kaplan–Meier method and were compared between subgroups using the log rank test. Toxicity was classified using common terminology criteria of adverse events version 5.0. Eighteen patients with inoperable MSC with neck lymph node metastasis including 12 men and 6 women with a median age of 67 years were analyzed. The histologic diagnoses were as follows: 16 patients had squamous cell carcinomas and 2 had other histology. Four patients had stage T3 MSC, 6 had T4a and 8 had T4b. Among 18 patients, 7 received concurrent systemic chemotherapy and 11 received selective arterial chemo-infusion. The median follow-up period was 17 months. The 2-year LC, PFS and OS rates for the entire cohort were 34, 31 and 46%, respectively. No significant differences were observed for LC, PFS and OS rates between systemic chemotherapy and selective arterial chemo-infusion cohorts. Grade 3 or higher acute toxicity, including both non-hematological and hematological, was observed in nine patients (50%), while no grade 3 or higher late toxicity was observed. In conclusion, we described the results of definitive RT for MSCs with neck lymph node metastasis. Local recurrence of primary tumor was a frequent pattern of failure and it should be addressed in future study.  相似文献   
12.
WS009 A and B novel endothelin receptor antagonists, have been isolated from the fermentation broth of Streptomyces sp. No. 89009. These antagonists were purified from the culture filtrate followed by Diaion SP-207, DEAE Toyopearl column chromatography and HPLC. WS009 A and B showed selective activity in an endothelin receptor binding assay with IC50 of 5.8 x 10(-6) M and 6.7 x 10(-7) M, respectively. On the basis of spectroscopic and chemical evidence, the structures of WS009 A and B have been established as 1 and 3, and are highly hydroxylated benz[a]anthraquinone chromophores.  相似文献   
13.
BACKGROUND: Neutrophil infiltration and lipid peroxide accumulation are involved in reperfusion-induced gastric mucosal injury in nitric oxide-depleted rats. AIM: To assess the effect of vitamin E on this injury. METHODS: After ischaemia-reperfusion, the total area of erosions, lipid peroxide contents in gastric mucosa, and gastric neutrophil accumulation were compared between nitric oxide-depleted rats with deficient, normal, and increased vitamin E intake over 8 weeks. Thiobarbituric acid-reactive substances and tissue-associated myeloperoxidase activity were measured in gastric mucosa as indices of lipid peroxidation and neutrophil infiltration. RESULTS: The total area of erosions was significantly increased in the vitamin E-deficient group compared with the sufficient-intake and vitamin-supplemented groups. Both thiobarbituric acid-reactive substances and myeloperoxidase activity also were significantly increased in the vitamin E-deficient group compared with others. The total area of erosions closely paralleled the increases in both thiobarbituric acid-reactive substances and myeloperoxidase activity. CONCLUSION: These results indicate that the inhibition of lipid peroxidation and interference with neutrophil infiltration by vitamin E may be responsible for its cytoprotective effect in ischaemia-reperfusion.  相似文献   
14.
Hypertension is a pervasive public health concern due to strong associations with cardiovascular diseases and stroke. Alternatively, the associations between hypertension and the risk of Alzheimer’s disease are complex and recent large sample studies reported positive associations. In this paper, we examine the associations between diastolic blood pressure (BP) and subsequent changes in brain structure and cognitive function over several years by multiple regression analyses (with adjustment for a wide range of potential confounding variables) among a large cohort from the UK Biobank. Higher baseline diastolic BP was associated with a slightly smaller relative increase (relative improvements) in reaction time and a slightly greater reduction in depression scores. Higher baseline diastolic BP was also associated with a greater total gray matter volume (GMV) retention, while aging alone was associated with GMV reduction. White matter microstructural analyses revealed that a greater diastolic BP was associated with reduced longitudinal mean and regional fractional anisotropy, greater increases in mean and regional mean diffusivity, radial diffusivity, and axial diffusivity, a greater decline in mean intracellular volume fraction, and greater increases in mean and regional isotropic volume fraction. These white matter microstructural changes were consistent with those seen in the aging process. Additional analyses revealed a greater cheese intake level at baseline, which is associated with a subsequent decline in diastolic BP and a relative subsequent increase in depressive tendency together with a relative increase in fluid intelligence and visuospatial memory performance. These results are congruent with the view that a higher BP in the aging brain has a complex role.  相似文献   
15.
Objective To investigate the risk factors for the development of Pneumocystis jirovecii pneumonia (PCP) in patients with rheumatoid arthritis (RA) undergoing methotrexate (MTX) therapy. Methods This single-center retrospective cohort study included consecutive patients with RA who received MTX for at least one year. The study population was divided into PCP and non-PCP groups, depending on the development of PCP, and their characteristics were compared. We excluded patients who received biologic disease-modifying anti-rheumatic drugs (DMARDs), Janus kinase inhibitors, and anti-PCP drugs for prophylaxis. Results Thirteen patients developed PCP, and 333 did not develop PCP. At the initiation of MTX therapy, the PCP group had lower serum albumin levels, a higher frequency of pulmonary disease and administration of DMARDs, and received a higher dosage of prednisolone (PSL) than the non-PCP group. A multivariate Cox regression analysis revealed that the concomitant use of PSL [hazard ratio (HR) 5.50, p=0.003], other DMARDs (HR 5.98, p=0.002), and serum albumin <3.5 mg/dL (HR 4.30, p=0.01) were risk factors for the development of PCP during MTX therapy. Patients with these risk factors had a significantly higher cumulative probability of developing PCP than patients who lacked these risk factors. Conclusion Clinicians should pay close attention to patients with RA who possess risk factors for the development of PCP during MTX therapy.  相似文献   
16.
MR imaging of primary malignant lymphoma of the pancreas   总被引:2,自引:0,他引:2  
Pancreatic lymphoma is rare and is usually found as a large pancreatic mass. We report the case of a small 2-cm pancreatic lymphoma in a 54-year-old woman that had its histological origin in the pancreatic parenchyma. The mass showed homogeneously high signal-intensity on T2-weighted images and low signal-intensity on T1-weighted images. The infiltrative nature and hypovascularity in early-phase dynamic contrast study without encasement of arteries and veins were well demonstrated by MR imaging and were consistent with malignant lymphoma.  相似文献   
17.
18.
Cryopyrin-associated periodic syndrome (CAPS) is a spectrum of systemic autoinflammatory disorders in which the majority of patients have mutations in the cold-induced autoinflammatory syndrome (CIAS)1 gene. Despite having indistinguishable clinical features, some patients lack CIAS1 mutations by conventional nucleotide sequencing. We recently reported a CAPS patient with mosaicism of mutant CIAS1, and raised the possibility that CIAS1 mutations were overlooked in "mutation-negative" patients, due to a low frequency of mosaicism. To determine whether there were latent mutant cells in "mutation-negative" patients, we sought to identify mutation-associated biologic phenotypes of patients' monocytes. We found that lipopolysaccharide selectively induced necrosis-like cell death in monocytes bearing CIAS1 mutations. Monocyte death correlated with CIAS1 up-regulation, was dependent on cathepsin B, and was independent of caspase-1. Cell death was intrinsic to CIAS1-mutated monocytes, was not mediated by the inflammatory milieu, and was independent of disease severity or anti-IL-1 therapy. By collecting dying monocytes after lipopolysaccharide treatment, we succeeded in enriching CIAS1-mutant monocytes and identifying low-level CIAS1-mosaicism in 3 of 4 "mutation-negative" CAPS patients. Our findings reveal a novel effect of CIAS1 mutations in promoting necrosis-like cell death, and demonstrate that CIAS1 mosaicism plays an important role in mutation-negative CAPS patients.  相似文献   
19.
BACKGROUND/AIMS: To determine an appropriate surgical treatment for patients with multiple liver metastases, we evaluated the efficacy of two-stage hepatectomy in patients with multiple bilobular liver metastases from colorectal carcinoma. METHODOLOGY: Some patients with multiple liver metastases are not candidates for a complete resection by a single hepatectomy, even when downstaged by chemotherapy, after portal embolization. In two-stage hepatectomy, the highest possible number of tumors is resected in a first, noncurative intervention, and the remaining tumors are resected after a period of liver regeneration. Two-stage hepatectomy was performed in 11 patients. RESULTS: Two-stage hepatectomy was feasible in all of the 11 patients. In 3 of them, the first stage was a major resection (more extensive than a lobectomy). This first hepatectomy was uneventful in all patients. The second hepatectomy was also uneventful in nine patients, but in one of the other two, a perihepatic fluid infection occurred, and in the other, postoperative liver failure developed due to a right subphrenic abscess. However, all patients were discharged. The percentage of the expected resection volume at one time, calculated from CT volumetry, was 75.5+/-1.2% and the prognostic score as surgical risk was 56.6+/-4.5. In two-stage hepatectomy cases, the percentage of the resected volume and the prognostic score in the first hepatectomy were 25.4+/-6.4% and 6.7+/-7.3, and in the second, 45.7+/-4.5% and 28.5+/-5.8. During the follow-up procedures, a residual hepatic recurrence was observed in 6 patients, and pulmonary recurrence in 9. The 1- and 3-year survival rates after the first hepatectomy were 90% and 45%, with median survivals of 18 months from the first hepatectomy. CONCLUSIONS: Two-stage hepatectomy is a surgical modality intended for patients with initial unresectable metastases. However, following such surgery, protective treatment against residual liver recurrence and lung metastasis will be a most important issue.  相似文献   
20.
BACKGROUND: Endoscopic submucosal dissection (ESD) of early gastric cancer is less invasive than surgical resection, and if technically feasible, it may result in less long-term morbidity than does incisional surgery. However, ESD is technically difficult in patients who have had a previous distal gastrectomy. OBJECTIVE: Our purpose was to retrospectively assess the results of ESD of early gastric cancer in the remnant stomach. DESIGN: Case series. SETTING AND PATIENTS: A total of 31 lesions in 30 patients with early remnant gastric cancer were treated with ESD at Okayama University Hospital, Tsuyama Central Hospital, Hiroshima City Hospital, Kagawa Prefectural Central Hospital, and Mitoyo General Hospital from March 2001 to January 2007. INTERVENTION: ESD. MAIN OUTCOME MEASUREMENTS: En bloc resection rate, complete resection rate, operation time, and complications. RESULTS: En bloc resection and complete resection were achieved in 30 (97%) and in 23 (74%) lesions, respectively. The median operation time required for ESD in the remnant stomach was 113 minutes (range 45-450 minutes). Perforation occurred in 4 (13%). The incidence of delayed bleeding requiring blood transfusion was 0%. LIMITATION: Short duration of follow-up. CONCLUSIONS: ESD is feasible in the remnant stomach but has a relatively high complication rate and should only be performed by experienced endoscopists.  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