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   13329篇
  免费   1735篇
  国内免费   306篇
耳鼻咽喉   215篇
儿科学   278篇
妇产科学   128篇
基础医学   760篇
口腔科学   188篇
临床医学   907篇
内科学   885篇
皮肤病学   542篇
神经病学   212篇
特种医学   2184篇
外国民族医学   15篇
外科学   1211篇
综合类   1585篇
预防医学   1068篇
眼科学   197篇
药学   584篇
  4篇
中国医学   288篇
肿瘤学   4119篇
  2024年   6篇
  2023年   199篇
  2022年   220篇
  2021年   443篇
  2020年   473篇
  2019年   462篇
  2018年   501篇
  2017年   502篇
  2016年   603篇
  2015年   630篇
  2014年   1017篇
  2013年   1317篇
  2012年   881篇
  2011年   875篇
  2010年   657篇
  2009年   592篇
  2008年   599篇
  2007年   576篇
  2006年   555篇
  2005年   514篇
  2004年   437篇
  2003年   405篇
  2002年   334篇
  2001年   314篇
  2000年   248篇
  1999年   208篇
  1998年   171篇
  1997年   168篇
  1996年   163篇
  1995年   129篇
  1994年   115篇
  1993年   100篇
  1992年   88篇
  1991年   102篇
  1990年   80篇
  1989年   89篇
  1988年   74篇
  1987年   66篇
  1986年   61篇
  1985年   79篇
  1984年   60篇
  1983年   54篇
  1982年   43篇
  1981年   34篇
  1980年   39篇
  1979年   30篇
  1978年   13篇
  1977年   15篇
  1976年   16篇
  1975年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
陈晓亮 《中国校医》2022,36(9):687-690
目的 探讨调强放射治疗对乳腺癌保乳术后患者的影响。方法 选取2015年3月—2019年10月在本院接受保乳术治疗的98例乳腺癌患者作为研究对象,按随机数字表法分为观察组与对照组,每组各49例。对照组采用常规放射治疗,观察组采用调强放射治疗。比较2组疗效、计划靶区剂量学、肌钙蛋白水平、预后情况。结果 观察组疗效总有效率为83.67%,高于对照组的65.31%,差异具有统计学意义(χ2=4.350,P=0.037);观察组计划靶区V100%、V105%分别为(9.68±0.65)%、(1.03±0.06)%,分别低于对照组的(42.02±4.87)%、(24.51±2.54)%,差异具有统计学意义(t=46.076、64.691,P值均<0.001);放疗后,观察组和对照组肌钙蛋白分别为(0.116±0.012)ng/mL、(0.260±0.019)ng/mL,分别高于放疗前的(0.059±0.010)ng/mL、(0.057±0.009)ng/mL,差异具有统计学意义(P<0.05),但观察组肌钙蛋白较对照组低,差异有统计学意义(t=44.855,P<0.001);观察组的无瘤生存率为97.96%,高于对照组的83.67%,差异具有统计学意义(χ2=4.405,P=0.036)。结论 对乳腺癌保乳术后患者辅以调强放射治疗,可提高临床疗效,调节靶区照射剂量均匀性、适应性,避免心肌及其他周围组织损伤,并提高无瘤生存率,改善预后。  相似文献   
2.
Background and study aimsPregnancy in association with cirrhosis is a rather uncommon and highly risky situation for both mother and child. We aim to study all factors and the utility of liver stiffness (LS) measurement by Acoustic Radiation Force Impulse elastography (ARFI) to predict hepatic decompensation in pregnant cirrhotic patients.Patients and methodsWe prospectively recruited 224 pregnant women at the multidisciplinary clinic of liver disease with pregnancy, Cairo University. LS was measured using ARFI (Siemens ACUSON S3000 ultrasound system) during the second trimester and 8–12 weeks post-delivery. The outcome of pregnancy and the incidence of hepatic decompensation were assessed.ResultsOur cohort comprised 128 normal pregnancies, 37 patients with pregnancy-related liver disease (Intrahepatic cholestasis (n = 6), preeclampsia (n = 23), and hyperemesis gravidarum (n = 8)) and 59 patients with an established chronic liver disease not related to pregnancy. In all patients, LS significantly decreased after delivery from 1.19 m/s to 0.94 m/s (P < 0.001). In multivariate analysis, LS was an independent predictor for the outcome of pregnancy in all patients (odds ratio (OR) = 5.442 (3.01–6.82), cut-off = 1.21 m/s). Patients with cirrhosis, mean LS was 1.57 ± 0.66 m/s and 26 (44%) patients had hepatic decompensation (hepatocellular jaundice (n = 8), ascites (n = 9) and variceal bleeding (n = 6)). In multivariate analysis; LS, platelets, albumin, and bilirubin were independent predictors of decompensation post-delivery and the OR for LS was 6.141(4.32–7.98). The optimal cut off value of LS to predict decompensation was 1.46 m/s (8.4 kPa) with AUROC of 0.827.ConclusionLS can be used to predict hepatic decompensation after delivery in pregnant women with manifest cirrhosis.  相似文献   
3.
Radiation therapy is a complex process involving multiple professionals and steps from simulation to treatment planning to delivery, and these procedures are prone to error. Additionally, the imaging and treatment delivery equipment in radiotherapy is highly complex and interconnected and represents another risk point in the quality of care. Numerous quality assurance tasks are carried out to ensure quality and to detect and prevent potential errors in the process of care. Recent developments in artificial intelligence provide potential tools to the radiation oncology community to improve the efficiency and performance of quality assurance efforts. Targets for artificial intelligence enhancement include the quality assurance of treatment plans, target and tissue structure delineation used in the plans, delivery of the plans and the radiotherapy delivery equipment itself. Here we review recent developments of artificial intelligence applications that aim to improve quality assurance processes in radiation therapy and discuss some of the challenges and limitations that require further development work to realise the potential of artificial intelligence for quality assurance.  相似文献   
4.
5.
《Cancer radiothérapie》2022,26(3):502-516
The aim of the review was to present the current literature status about replanning regarding anatomical and dosimetric changes in the target and OARs in the head and neck region during radiotherapy, to discuss and to analyze factors influencing the decision for adaptive radiotherapy of head and neck cancer patients. Significant progress has been made in head and neck patients’ evaluation and qualification for adapted radiotherapy over the past ten years. Many factors leading to anatomical and dosimetric changes during treatment have been identified. Based on the literature, the most common factors triggering re-plan are weight loss, tumor and nodal changes, and parotid glands shrinkage. The fluctuations in dose distribution in the clinical area are significant predictive factors for patients’ quality of life and the possibility of recovery. It has been shown that re-planning influence clinical outcomes: local control, disease free survival and overall survival. Regarding literature studies, it seems that adaptive radiotherapy would be the most beneficial for tumors of immense volume or those in the nearest proximity of the OARs. All researchers agree that the timing of re-planning is a crucial challenge, and there are still no clear consensus guidelines for time or criteria of re-planning. Nowadays, thanks to significant technological progress, the decision is mostly made based on observation and supported with IGRT verification. Although further research is still needed, adaptive strategies are evolving and now became the state of the art of modern radiotherapy.  相似文献   
6.
目的 利用体外细胞共培养技术模拟体内肺组织微环境,探索树突状细胞(DC)在辐射损伤细胞的抗原提呈作用。方法 60Co γ射线照射的小鼠肺上皮细胞(MLE-12)与骨髓来源DC和/或脾T淋巴细胞培养48 h,流式细胞术检测DC细胞共刺激分子CD80/86和抗原肽识别复合物MHC Ⅰ/Ⅱ表达水平,T细胞活化标志CD69/28/152表达水平以及CD4+和CD8+亚群细胞数。结果 60Co γ射线照射的MLE-12细胞凋亡率呈剂量依赖性增高,明显刺激DC细胞CD80/86和MHC II表达,但对T细胞无直接活化作用;6 Gy照射的MLE-12细胞与DC细胞和T淋巴细胞共培养48 h,T细胞CD69和CD28表达增加,CD4+和CD8+亚群细胞数均明显高于对照组,同时DC细胞出现CD86和MHCI特异性高表达。结论 辐射损伤细胞可刺激DC细胞抗原提呈功能,并对T细胞进行活化。  相似文献   
7.
目的 采用响应面法优选三七生药粉乙醇灭菌工艺,考察不同灭菌方式对三七生药粉灭菌效果及质量的影响。方法 以人参皂苷Rg1、人参皂苷Rb1及三七皂苷R1含量,皂苷总量和灭菌率的综合评分为指标,乙醇体积分数、乙醇用量、灭菌时间、干燥温度为因素,在单因素试验的基础上,采用响应面法优化三七乙醇灭菌工艺;分别对比湿热灭菌、辐照灭菌、干热灭菌和乙醇灭菌法对三七生药粉灭菌效果和质量的影响。结果 最佳灭菌工艺为乙醇体积分数74%、乙醇用量26%、灭菌时间2.2 h、干燥温度75 ℃;对比灭菌前后三七粉的质量,湿热灭菌和干热灭菌后三七中皂苷含量显著降低,其中湿热灭菌后皂苷含量已不符合《中华人民共和国药典》2020年版标准。指纹图谱显示,乙醇灭菌与生药材相似度较高,表明乙醇灭菌对三七影响不大。结论 乙醇灭菌法与其他灭菌方法相比,可在较低温度、更短时间、更加安全地得到符合规定的三七生药粉,且优选得到的灭菌工艺稳定可行、重复性好,可为其后续工艺开发和工业化生产提供参考。  相似文献   
8.
《Cancer radiothérapie》2022,26(4):611-615
In order to provide more convenient irradiation regimens for patient comfort, radiation facility organization and health expenses, new hypofractionated protocols have been evaluated. Moderately (dose/fraction: 2.3 to 3 Gy), then ultra (dose/fraction: 5.2 to 6.1 Gy) hypofractionated irradiations were first validated. The current question is: is it possible to go forward using extreme hypofractionated regimens (EHR) based on 1 to 3 fractions. Different irradiation techniques are under investigation. However, brachytherapy remains the smartest way to deliver a high dose in a small volume. We report prospective and retrospective study results which evaluated EHR for breast and prostate brachytherapy. While oncological outcome and toxicity profile appear extremely encouraging for low-risk breast cancer after a 1 to 4 fractions (6.25 to 20 Gy/fraction), the use of a single fraction of 19 to 23 Gy appears debatable for prostate cancer. Brachytherapy represents an emblematic example of EHR but longer follow-up and more mature results are awaited in order to specify the right indications and refine the EQD2 calculation method including new biological and technical factors.  相似文献   
9.
目的:探究基于AMP活化蛋白激酶(AMPK)/哺乳动物雷帕霉素靶蛋白(mTOR)信号通路介导的自噬途径研究黄芪多糖(APS)对急性放射性肠炎大鼠肠黏膜的保护作用。方法:对SD大鼠进行12 Gy单次照射,制备急性放射性肠炎模型,随机分为模型组、APS(2 g/kg)组、AMPK抑制剂compound C(CC,0.2 mg/kg)组和APS(2 g/kg)+CC(0.2 mg/kg)组,每组12只;另取12只大鼠不做处理,设为对照组。以药物分组干预处理后,检测大鼠一般情况,做临床症状评分;HE染色观察大鼠肠黏膜病理形态;试剂盒检测大鼠血清白细胞介素17(IL-17)、IL-1β、肿瘤坏死因子α(TNF-α)、肠型脂肪酸结合蛋白(I-FABP)、细胞间黏附分子1(ICAM-1)和二胺氧化酶(DAO)水平;Western blot法检测大鼠肠黏膜组织自噬相关蛋白(beclin-1和LC3-II/LC3-I)及AMPK/mTOR通路相关蛋白(p-AMPK/AMPK和p-mTOR/mTOR)水平。结果:与对照组相比,模型组大鼠肠黏膜组织出现严重病理损伤,肠黏膜组织beclin-1、LC3-II/...  相似文献   
10.
作为半刚性的、无血管和神经的结缔组织,软骨具有承重、应力缓冲和辅助运动等多种生理功能。软骨固有的修复能力差,损伤不易逆转且治疗难度大。近年来,大量研究结果显示适宜的电磁辐射对软骨细胞形态的维持及其细胞因子的分泌、软骨细胞外基质的稳态以及骨关节炎的治疗等都具有积极的意义。笔者就电磁辐射对软骨的生物学效应及其可能的作用机制作一综述。  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