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   42072篇
  免费   3578篇
  国内免费   1592篇
耳鼻咽喉   164篇
儿科学   283篇
妇产科学   335篇
基础医学   4063篇
口腔科学   1068篇
临床医学   5050篇
内科学   2487篇
皮肤病学   462篇
神经病学   1403篇
特种医学   948篇
外国民族医学   2篇
外科学   2471篇
综合类   8788篇
现状与发展   2篇
预防医学   4704篇
眼科学   447篇
药学   7835篇
  184篇
中国医学   5735篇
肿瘤学   811篇
  2024年   180篇
  2023年   555篇
  2022年   1350篇
  2021年   1788篇
  2020年   1530篇
  2019年   980篇
  2018年   930篇
  2017年   1278篇
  2016年   1433篇
  2015年   1453篇
  2014年   2893篇
  2013年   3011篇
  2012年   3013篇
  2011年   3149篇
  2010年   2433篇
  2009年   2005篇
  2008年   2061篇
  2007年   2405篇
  2006年   1832篇
  2005年   1566篇
  2004年   1358篇
  2003年   1120篇
  2002年   928篇
  2001年   806篇
  2000年   690篇
  1999年   627篇
  1998年   554篇
  1997年   458篇
  1996年   458篇
  1995年   462篇
  1994年   391篇
  1993年   387篇
  1992年   341篇
  1991年   319篇
  1990年   275篇
  1989年   236篇
  1988年   241篇
  1987年   219篇
  1986年   199篇
  1985年   324篇
  1984年   235篇
  1983年   170篇
  1982年   162篇
  1981年   108篇
  1980年   83篇
  1979年   60篇
  1978年   46篇
  1977年   30篇
  1976年   35篇
  1975年   19篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
891.
The interaction between tissues and biomaterials (BM) has the purpose of improving and replacing anatomical parts of the human body, avoiding the occurrence of adverse reactions in the host organism. Unfortunately, the early failure of implants cannot be currently avoided, since neither a good mixture of mechanical and chemical characteristics of materials nor their biocompatibility has been yet achieved. Bioactive glasses are recognized to be a fine class of bioactive substances for good repair and replacement. BM interact with living bones through the formation of a hydroxyapatite surface layer that is analogous to bones. Bioglasses’ composition noticeably affects their biological properties, as does the synthesis method, with the best one being the versatile sol-gel technique, which includes the change of scheme from a ‘sol’ fluid into a ‘gel’. This process is widely used to prepare many materials for biomedical implants (e.g., hip and knee prostheses, heart valves, and ceramic, glassy and hybrid materials to serve as carriers for drug release). Nanoparticles prepared by the sol-gel method are interesting systems for biomedical implementations, and particularly useful for cancer therapy. This review provides many examples concerning the synthesis and characterization of the above-mentioned materials either taken from literature and from recently prepared zirconia/polyethylene glycol (PEG) hybrids, and the corresponding results are extensively discussed.  相似文献   
892.
BackgroundAttempts to improve protocol standards of marker-based clinical gait analysis (CGA) have been one of the main focuses of research to enhance robustness and reliability outcomes since the 1990s. Determining joint centres and axes constitutes an important aspect of those protocols. Although the hip joint is more prominent in such studies, knee joint center (KJC) and axis (KJA) directly affect all outcomes.Research questionWhat recommendations arise from the study of the scientific literature for determining knee joint parameters (KJP) for protocols of CGA?MethodsA systematic, electronic search was conducted on November 2018 using three databases with the keyword combination (“functional approach” OR “functional method” OR “functional calibration”) AND (“hip joint” OR “knee joint” OR “ankle joint”) and analyzed by four reviewers. Given the existence of a recent review about the hip joint and the lack of material about the ankle joint, only papers about the knee joint were kept. The references cited in the selected papers were also screened in the final round of the search for these publications.The quality of the selected papers was assessed and aspects regarding accuracy, repeatability, and feasibility were thoroughly considered to allow for a comparison between studies. Technical aspects, such as marker set choice, KJP determination techniques, demographics, and functional movements, were also included.ResultsThirty-one papers were included and on average received a rating of about 75 % according to the quality scale used. The results showed that functional methods are superior or equivalent to predictive methods to estimate the KJA, while a regression method was slightly better for KJC prediction.SignificanceCalibration methods should be applied to CGA whenever feasibility is reached. No study to date has focused on evaluating the in vivo RoM required to obtain reliable and repeatable results and future work should aim in this direction.  相似文献   
893.
ObjectivesTo investigate the influence of unilateral disc displacement (DD) in the temporomandibular joint (TMJ) on the stress in the contralateral joint, with a normally-positioned disc, during clenching.Study designA finite element model of the TMJ was constructed based on MRI and 3D-CT of a single patient with a unilateral DD. A second model with bilateral normally-positioned discs served as a reference. The differences in stress distribution in various TMJ components during clenching were predicted with these models.ResultsIn the unaffected joint of the unilateral DD model, the largest von Mises stress at the start of clenching was predicted in the inferior surface of the disc and increased by 30% during clenching. In the connective tissue the largest stress (1.16 MPa) did not reduce during clenching, in contrast to the (unaffected) joints of the reference model. In the affected joint, the largest stress was predicted in the temporal cartilage throughout clenching. In the surrounding connective tissue, the largest stress (1.42 MPa) hardly changed during clenching indicating no, or negligible, stress relaxation.ConclusionsThis suggested that a unilateral DD could affect the stresses in the unaffected (contralateral) joint during clenching, where it may lead to weakening of the tissues that keep the disc on the top of the condyle. The results may be helpful in counseling worried patients, since they give insight into possible future developments of the disorder.  相似文献   
894.
目的 制备高纯度3,5-O-二咖啡酰基奎宁酸,并评价其对人宫颈癌HeLa细胞的抗增殖活性。方法 采用柱色谱提取法和中压液相色谱法从奇蒿花中分离、纯化得到高纯度的3,5-O-二咖啡酰基奎宁酸。采用MTT法评价该化合物对人宫颈癌HeLa细胞的体外抗增殖活性。结果 柱色谱提取的提取率和中压液相色谱法的回收率分别为99.0%,61.2%,总回收率为54.0%。随着3,5-O-二咖啡酰基奎宁酸浓度升高,HeLa细胞存活率下降,细胞形态损伤增加,受试药物的IC50值为26.5µg·mL-1结论 本研究提供了一种简单、高效、节能的3,5-O-二咖啡酰基奎宁酸制备方法。3,5-O-二咖啡酰基奎宁酸对HeLa细胞具有一定的体外抗增殖活性。  相似文献   
895.
In psychiatry, clinicians use criteria sets from the Diagnostic and Statistical Manual of Mental Disorders to diagnose mental disorders. Most criteria sets have several symptom domains, and in order to be diagnosed, an individual must meet the minimum number of symptoms required by each domain. Some efforts are now focused on adding biomarkers to these symptom domains to facilitate the detection of and highlight the neurobiological basis of psychiatric disorders. Thus, a new criteria set may consist of both clinical symptom counts in several domains and continuous biomarkers. In this paper, we propose a method to integrate classification rules from multiple data sources to estimate an optimal criteria set. Each domain-specific rule can be counts of symptoms, a linear function of symptoms, or even nonparametric. The overall classification rule is the intersection of these domain-specific rules. Based on examining the expected population loss function, we propose two iterative algorithms using either support vector machines or logistic regression to fit intersection rules consistent with the Diagnostic and Statistical Manual of Mental Disorders. In simulation studies, these proposed methods are comparable with the true decision rule. The methods are applied to the motivating study to construct a criteria set for complicated grief. The developed criteria set shows a substantial improvement in sensitivity and specificity compared to the current standards on an independent validation study.  相似文献   
896.
897.
898.
目的评价两种方法学检测糖类抗原242(CA242)结果的可比性,以评估磁微粒化学发光法检测CA242是否能够满足临床的需求。方法根据美国临床和实验室标准协会(CLSI)新指南EP9-A3文件要求,收集2018年1-7月首都医科大学附属北京康复医院和北京大学首钢医院肿瘤患者检测剩余的新鲜血清标本100例,以Fujirebio Diagnostics AB的酶联免疫法为参比方法,安图生物的磁微粒化学发光法为评估方法,对2种方法检测CA242的结果进行方法学比对和偏移评估。选择Passing-Baklok回归方法进行线性拟合,采用Wilcoxon符号秩检验及Spearman相关分析。结果在4.31~295.63 U/ml范围内,2种方法学的CA242检测结果具有较好的相关性(r=0.991,截距0.652)。参比方法和评估方法比较,差异无统计学意义[(53.75±6.69)U/ml比(56.11±6.86)U/ml,t=0.246,P=0.806]。将CA242的医学决定水平25.00 U/ml代入选取的最佳回归模型拟合方程,计算得到的相对偏移3.52%,<1/2TEa±12.5%(TEa为国家卫生健康委临床检验中心室间质量评审允许总误差),满足要求。结论安图生物的磁微粒化学发光法和Fujirebio Diagnostics AB酶联免疫法检测CA242结果具有可比性,满足临床需要。  相似文献   
899.
目的 分析《药物分析》课程在当今药学本科教育培养过程中的现状,探索《药物分析》课程在新时代药学教育背景下的教学改革与创新,构建符合药学培养要求、满足社会市场需要的复合型药学人才培养模式。方法 第一阶段,开展教学改革的建议和需求调查;第二阶段,开展《药物分析》课程改革探索与实践;第三阶段,教学效果评价。结果 需求调查显示《药物分析》课程的教学内容、课程设计、教学手段亟须进一步优化和拓展。结论 该课程通过调整教学内容、拓展教学手段、创新多元化实践教学、融入"课程思政"建设等,激发了学生的学习兴趣和创新精神,强化了学生理论素养和实践能力,培养了其国际化视野和崇高的职业道德。  相似文献   
900.
AimThe aim of this study was to further explore expressions of existential experiences by patients diagnosed with malignant melanoma (MM).MethodSemi-structured interviews were performed consecutively after diagnosis among 30 patients with MM. The methodological approach was inspired by Gadamer's hermeneutic philosophy.ResultsThe analysis of expressions of existential experiences after having been diagnosed with malignant melanoma revealed that it is an existential process that people go through, beginning with feelings of suddenly becoming groundless at the time of the diagnosis, including being empty and in a vacuum, being in chaos and uncertainty and being confronted with one's own death. Next theme searching for solid ground included striving to understand what lies ahead, striving to find a balance in life – fighting, hoping, going on living and striving to prioritize family. The last theme creating islands of solid ground when living with cancer included understanding what is meaningful in life, living in the moment – seizing the day and keeping watch on the body.ConclusionOn being diagnosed with malignant melanoma, people go through a process where many questions emerge, including an existential turmoil, which health professionals should be aware of to provide these patients with sufficient support.  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