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   232066篇
  免费   30627篇
  国内免费   9031篇
耳鼻咽喉   1704篇
儿科学   1885篇
妇产科学   5229篇
基础医学   16646篇
口腔科学   2178篇
临床医学   19910篇
内科学   28839篇
皮肤病学   1480篇
神经病学   904篇
特种医学   8342篇
外国民族医学   253篇
外科学   35560篇
综合类   29718篇
现状与发展   38篇
一般理论   3篇
预防医学   10765篇
眼科学   113篇
药学   16699篇
  141篇
中国医学   5899篇
肿瘤学   85418篇
  2024年   211篇
  2023年   4615篇
  2022年   6869篇
  2021年   11577篇
  2020年   11435篇
  2019年   10280篇
  2018年   9964篇
  2017年   10265篇
  2016年   11184篇
  2015年   12950篇
  2014年   19181篇
  2013年   18625篇
  2012年   15487篇
  2011年   15720篇
  2010年   11857篇
  2009年   12112篇
  2008年   12407篇
  2007年   11637篇
  2006年   10481篇
  2005年   8493篇
  2004年   6879篇
  2003年   5751篇
  2002年   4919篇
  2001年   4467篇
  2000年   3705篇
  1999年   3021篇
  1998年   2419篇
  1997年   2134篇
  1996年   1724篇
  1995年   1786篇
  1994年   1528篇
  1993年   1156篇
  1992年   1014篇
  1991年   894篇
  1990年   675篇
  1989年   629篇
  1988年   537篇
  1987年   444篇
  1986年   348篇
  1985年   442篇
  1984年   350篇
  1983年   227篇
  1982年   253篇
  1981年   243篇
  1980年   202篇
  1979年   143篇
  1978年   120篇
  1977年   93篇
  1976年   84篇
  1975年   52篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
41.
42.
43.
ObjectivesThe aim of this meta-analysis was to conduct a contemporary systematic review of high quality non-randomised controlled trials to determine the effect of pre-liver transplantation (LT) transarterial chemoembolisation (TACE) on long-term survival and complications of hepatocellular carcinoma (HCC) patients.BackgroundTACE is used as a neoadjuvant therapy to mitigate waitlist drop-out for patients with HCC awaiting LT. Previous studies have conflicting conclusions on the effect of TACE on long-term survival and complications of HCC patients undergoing LT.MethodsCINAHL, Cochrane Controlled Register of Trials, Embase, PubMed, and Web of Science were systematically searched. Baseline characteristics included number of patients outside Milan criteria, tumour diameter, MELD score, and time on the waiting list. Primary outcomes included 3- and 5-year overall and disease-free survival. Secondary outcomes included tumour recurrence, 30-day postoperative mortality, and hepatic artery and biliary complications.ResultsTwenty-one high-quality NRCTs representing 8242 patients were included. Tumour diameter was significantly larger in TACE patients (3.49 cm vs 3.15 cm, P = 0.02) and time on the waiting list was significantly longer in TACE patients (4.87 months vs 3.46 months, P = 0.05), while MELD score was significantly higher in non-TACE patients (10.81 vs 12.35, P = 0.005). All primary and secondary outcomes displayed non-significant differences.ConclusionPatients treated with TACE had similar survival and postoperative outcomes to non-TACE patients, however, they had worse prognostic features compared to non-TACE patients. These findings strongly support the current US and European clinical practice guidelines that neoadjuvant TACE can be used for patients with longer expected waiting list times (specifically >6 months). Randomised controlled trials would be needed to increase the quality of evidence.  相似文献   
44.
45.
Hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer is defined by the presence of the estrogen receptor and/or the progesterone receptor and the absence of HER2 gene amplification. HR-positive/HER2-negative breast cancer accounts for 65%–70% of all breast cancers, and incidence increases with increasing age. Treatment varies by stage, and endocrine therapy is the mainstay of treatment in both early stage and late-stage disease. Combinations with cyclin-dependent kinase 4/6 inhibitors have reduced distant recurrence in the early stage setting and improved overall survival in the metastatic setting. Chemotherapy is used based on stage and tumor biology in the early stage setting and after endocrine resistance for advanced disease. New therapies, including novel endocrine agents and antibody-drug conjugates, are now changing the treatment landscape. With the availability of new treatment options, it is important to define the optimal sequence of treatment to maximize clinical benefit while minimizing toxicity. In this review, the authors first discuss the pathologic and molecular features of HR-positive/HER2-negative breast cancer and mechanisms of endocrine resistance. Then, they discuss current and emerging therapies for both early stage and metastatic HR-positive/HER2-negative breast cancer, including treatment algorithms based on current data.  相似文献   
46.
Bladder cancer is common and one of the most costly cancer forms, due to a lack of curative therapies. Recently, clinical safety and efficacy of the alpha1-oleate complex was demonstrated in a placebo-controlled study of nonmuscle invasive bladder cancer. Our study investigated if long-term therapeutic efficacy is improved by repeated treatment cycles and by combining alpha1-oleate with low-dose chemotherapy. Rapidly growing bladder tumors were treated by intravesical instillation of alpha1-oleate, Epirubicin or Mitomycin C alone or in combination. One treatment cycle arrested tumor growth, with a protective effect lasting at least 4 weeks in mice receiving 8.5 mM of alpha1-oleate alone or 1.7 mM of alpha-oleate combined with Epirubicin or Mitomycin C. Repeated treatment cycles extended protection, defined by a lack of bladder pathology and a virtual absence of bladder cancer-specific gene expression. Synergy with Epirubicin was detected at the lower alpha1-oleate concentration and in vitro, alpha1-oleate was shown to enhance the uptake and nuclear translocation of Epirubicin, by tumor cells. Effects at the chromatin level affecting cell proliferation were further suggested by reduced BrdU incorporation. In addition, alpha1-oleate triggered DNA fragmentation, defined by the TUNEL assay. The results suggest that bladder cancer development may be prevented long-term in the murine model, by alpha1-oleate alone or in combination with low-dose Epirubicin. In addition, the combination of alpha1-oleate and Epirubicin reduced the size of established tumors. Exploring these potent preventive and therapeutic effects will be of immediate interest in patients with bladder cancer.  相似文献   
47.
BackgroundLiver resection is commonly performed for hepatic tumors, however preoperative risk stratification remains challenging. We evaluated the performance of contemporary prediction models for short-term mortality after liver resection in patients with and without cirrhosis.MethodsThis retrospective cohort study examined National Surgical Quality Improvement Program data. We included patients who underwent liver resections from 2014 to 2019. VOCAL-Penn, MELD, MELD-Na, ALBI, and Mayo risk scores were evaluated in terms of model discrimination and calibration for 30-day post-operative mortality.ResultsA total 15,198 patients underwent liver resection, of whom 249 (1.6%) experienced 30-day post-operative mortality. The VOCAL-Penn score had the highest discrimination (area under the ROC curve [AUC] 0.74) compared to all other models. The VOCAL-Penn score similarly outperformed other models in patients with (AUC 0.70) and without (AUC 0.74) cirrhosis.ConclusionThe VOCAL-Penn score demonstrated superior predictive performance for 30-day post-operative mortality after liver resection as compared to existing clinical standards.  相似文献   
48.
目的分析肝移植术后受者外周血CD19+CD24hiCD38hi B细胞占单个核细胞比例变化情况及其与急性细胞性排斥反应(ACR)之间的关系。 方法回顾性分析2013年12月至2015年12月在浙江大学医学院附属第一医院接受心脏死亡器官捐献肝移植的80例成人受者临床资料,根据术后是否发生ACR,将受者分为ACR组(25例)和非ACR组(55例)。术前、术后各个时间点抽取参加研究者静脉血并分离外周血单个核细胞,加入异硫氰酸荧光素-单克隆鼠抗人CD19抗体、藻红蛋白-单克隆鼠抗人CD24抗体和别藻蓝蛋白-单克隆鼠抗人CD38抗体,流式细胞仪检测各组CD19+CD24hiCD38hi B细胞百分比。采用t检验和单因素方差分析比较正态分布计量资料,采用χ2检验比较计数资料,采用Kaplan-Meier法绘制受试者工作特征曲线(ROC曲线)。P<0.05为差异有统计学意义。 结果ACR组、非ACR组受者术前外周血平均CD19+CD24hiCD38hi B细胞比例分别为(3.13±0.91)%、(3.49±0.83)%,差异无统计学意义(t=1.636,P>0.05)。ACR组术后发生ACR前外周血平均CD19+CD24hiCD38hi B细胞比例为(1.87±0.70)%。非ACR组受者术后3个月、6个月和1年外周血平均CD19+CD24hiCD38hi B细胞比例分别为(1.64±0.52)%、(1.63±0.56)%和(2.04±1.24)%,术后3、6个月平均值均低于术前和术后1年,差异均有统计学意义(P均<0.05)。ACR组受者发生ACR时外周血平均CD19+CD24hiCD38hi B细胞比例为(0.8±0.5)%,低于发生ACR前的平均水平(t=5.752,P<0.05),且低于非ACR组术后3个月、6个月和1年的平均水平(P<0.05)。ACR组受者接受抗排斥反应治疗后,CD19+CD24hiCD38hi B细胞比例也逐渐增加,ACR发生后7 d为(0.84±0.08)%,与ACR发生时相比差异无统计学意义(P>0.05);而发生30 d后达(1.65±0.18)%,与ACR发生时相比差异有统计学意义(P<0.05)。当截断值为1.015%时,CD19+CD24hiCD38hi B细胞比例预测ACR发生的敏感度和特异度分别为0.786和0.702,ROC曲线下面积为0.775(95%CI: 0.671~0.879,P<0.05)。 结论CD19+CD24hiCD38hi B细胞比例下降与肝移植术后ACR反应发生有关,并可作为预测ACR发生的细胞标志物。  相似文献   
49.
《Cancer radiothérapie》2022,26(4):542-546
PurposeModerate hypofractionated radiotherapy has become routine practice for a selected population of patients treated for early-stage breast cancer. In April 2020, the Fast Forward (FF) study was published which introduced another extreme hypofractionated radiotherapy regimen in five sessions over a week. The aim of this work is to evaluate the population of first patients in whom this regimen was used in our department, as well as the results in terms of early toxicity.Material and methodsWe retrospectively analysed all the patients treated in our department according to the Fast Forward protocol after establishing an institutional consensus regarding the selection of patients with breast cancer without indication for lymph node irradiation. All patients received breast-only irradiation at a total dose of 26 Gy in five fractions according to protocol. All patients were treated by modern conformational techniques with planning large volume coverage between 95 and 100%. Acute toxicity of the treatment was assessed using the NCI CTC v4.0 scale and the general condition was assessed according to the WHO classification.ResultsBetween August 2020 and May 2021, 30 patients were included, treated on the breast alone without complement on the tumour bed or irradiation of the lymph node areas. The median age of the patients was 80 years (range: 60–85 years) with performance status 2 in 27 cases (89%). Only one patient had metastatic disease (3%), one patient presented locally advanced and 28 (94%) patients had early stage disease. Three patients (10%) were treated in dorsal decubitus according to the “field in the field” technique and 27 patients (90%) in isocentric lateral decubitus, which made it possible to avoid the organs at risk such as the heart (average dose of less than 1 Gy) and the lungs. The early toxicity observed was grade I radio dermatitis in 8 patients (27%). No grade 2 and 3 toxicity, as well as radiation-induced pain or lymphedema were observed.ConclusionsThe results of this series of patients treated with hypofractionated radiotherapy according to the Fast Forward protocol on the breast alone with adapted techniques show that the protocol is feasible, with little early toxicity but a greater follow-up is necessary to assess long-term toxicity.  相似文献   
50.
Objective: Lung cancer is one of the unsafe diseases for human which reduces the patient life time. Generally, most of the lung cancers are identified after it has been spread into the lung parts and moreover it is difficult to find the lung cancer at the early stage. It requires radiologist and special doctors to find the tumoral tissue of the lung cancer. For this reason, the recommended work helps to segment the tumoral tissue of CT lung image in an effective way. Methods:  The research work uses hybrid segmentation technique to separate the lung cancer cells to diagnose the lung tumour. It is a technique which combines active contour along with Fuzzy c means to diagnose the tumoral tissue. Further the segmented portion was trained by Convolutional Neural Network (CNN) in order to classify the segmented region as normal or abnormal. Results: The evaluation of the proposed method was done by analyzing the results of test image with the ground truth image. Finally, the results of the implemented technique provided good accuracy, Peak signal to noise ratio (PSNR), Mean Square Error (MSE) value. In future the other techniques can be utilized to improve the details before segmentation. The proposed work provides 96.67 % accuracy. Conclusion: Hybrid segmentation technique involves several steps like preprocessing, binarization, thresholding, segmentation and feature extraction using GLCM.  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