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   221434篇
  免费   19189篇
  国内免费   5065篇
耳鼻咽喉   3390篇
儿科学   4178篇
妇产科学   3622篇
基础医学   18655篇
口腔科学   7494篇
临床医学   20136篇
内科学   20333篇
皮肤病学   2420篇
神经病学   11476篇
特种医学   6714篇
外国民族医学   14篇
外科学   25609篇
综合类   34998篇
现状与发展   9篇
一般理论   24篇
预防医学   27645篇
眼科学   2585篇
药学   20753篇
  335篇
中国医学   25821篇
肿瘤学   9477篇
  2024年   626篇
  2023年   4279篇
  2022年   6888篇
  2021年   10970篇
  2020年   10469篇
  2019年   11741篇
  2018年   10513篇
  2017年   9101篇
  2016年   8184篇
  2015年   7641篇
  2014年   15133篇
  2013年   15368篇
  2012年   13468篇
  2011年   14455篇
  2010年   11639篇
  2009年   10232篇
  2008年   9526篇
  2007年   9548篇
  2006年   8145篇
  2005年   6936篇
  2004年   5767篇
  2003年   5139篇
  2002年   3871篇
  2001年   3274篇
  2000年   2895篇
  1999年   2369篇
  1998年   1893篇
  1997年   1713篇
  1996年   1378篇
  1995年   1321篇
  1994年   1208篇
  1993年   1049篇
  1992年   955篇
  1991年   856篇
  1990年   757篇
  1989年   749篇
  1988年   696篇
  1987年   619篇
  1986年   570篇
  1985年   1829篇
  1984年   2093篇
  1983年   1303篇
  1982年   1735篇
  1981年   1204篇
  1980年   1030篇
  1979年   921篇
  1978年   752篇
  1977年   567篇
  1976年   707篇
  1975年   479篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Congenital diarrhea and enteropathies (CODEs) are a group of monogenic disorders that often present with severe diarrhea in the first weeks of life. Enteric anendocrinosis (EA), an extremely rare cause of CODE, is characterized by a marked reduction of intestinal enteroendocrine cells (EC). EA is associated with recessively inherited variants in Neurogenin-3 (NEUROG3) gene. Here we investigate a case of a male infant who presented with mysterious severe malabsorptive diarrhea since birth. Thorough clinical assessments and laboratory tests were successful to exclude the majority of differential diagnosis categories. However, the patient's diagnosis was not established until the genetic test using whole-exome sequencing (WES) was performed. We identified a novel homozygous missense disease-causing variant (DCV) in NEUROG3 (c.413C>G, p.Thr138Arg). Moreover, molecular dynamic simulation analysis showed that (p.Thr138Arg) led to a global change of the NEUROG3 orientation affecting its DNA binding capacity. To the best of our knowledge, this is the first time to apply WES to reach a differential diagnosis of patients with CODEs. Our study not only expands our knowledge about NEUROG3 variants and their clinical consequences but also proves that WES is a very effective tool for the diagnosis of CODEs. This might be of value in early diagnosis of diseases and prenatal CODEs detection.  相似文献   
72.
目的:探讨健康干预应用于肥胖中学生的效果。方法:抽取张掖市第一中学肥胖中学生180例,随机分为观察组与对照组,观察组实施健康干预,对照组仅予以常规健康教育,比较两组肥胖改善情况。结果:观察组干预效果显著优于对照组(P<0.05);干预后观察组的 BMI、腰围、胸围及皮脂厚度均较对照组显著降低(P<0.05)。结论:在肥胖中学生中实施健康干预有利于促进学生身体形态生长水平的改善,控制和降低学生 BMI和肥胖增长速度。  相似文献   
73.
Antibody-mediated rejection is a major complication in renal transplantation. The pathologic manifestations of acute antibody-mediated rejection that has progressed to functional impairment of a renal transplant have been defined in clinical biopsy specimens. However, the initial stages of the process are difficult to resolve with the unavoidable variables of clinical studies. We devised a model of renal transplantation to elucidate the initial stages of humoral rejection. Kidneys were orthotopically allografted to immunodeficient mice. After perioperative inflammation subsided, donor-specific alloantibodies were passively transferred to the recipient. Within 1 hour after a single transfer of antibodies, C4d was deposited diffusely on capillaries, and von Willebrand factor released from endothelial cells coated intravascular platelet aggregates. Platelet-transported inflammatory mediators platelet factor 4 and serotonin accumulated in the graft at 100- to 1000-fold higher concentrations compared with other platelet-transported chemokines. Activated platelets that expressed P-selectin attached to vascular endothelium and macrophages. These intragraft inflammatory changes were accompanied by evidence of acute endothelial injury. Repeated transfers of alloantibodies over 1 week sustained high levels of platelet factor 4 and serotonin. Platelet depletion decreased platelet mediators and altered the accumulation of macrophages. These data indicate that platelets augment early inflammation in response to donor-specific antibodies and that platelet-derived mediators may be markers of evolving alloantibody responses.  相似文献   
74.
陈宏宇  武文 《浙江预防医学》2020,31(10):1232-676
【目的】 值此《中国科技期刊研究》创刊30周年之际,思考科研评价体系的改变给中文科技期刊带来的影响,为中文期刊探寻发展路径。【方法】 结合对中文科技期刊困境的研究,提出应对策略。【结果】 近期国家陆续出台的纠偏评价导向的政策文件,为中文科技期刊既带来了发展机遇,也提出了挑战。【结论】 在重构符合中文科技期刊发展特点的评价体系的基础上,中文科技期刊应明确目标定位,面向国家需求,提升知识服务能力,建立品牌特色。  相似文献   
75.
PurposeTo compare morphological imaging features and CT texture histogram parameters between grade 3 pancreatic neuroendocrine tumors (G3-NET) and neuroendocrine carcinomas (NEC).Materials and methodsPatients with pathologically proven G3-NET and NEC, according to the 2017 World Health Organization classification who had CT and MRI examinations between 2006-2017 were retrospectively included. CT and MRI examinations were reviewed by two radiologists in consensus and analyzed with respect to tumor size, enhancement patterns, hemorrhagic content, liver metastases and lymphadenopathies. Texture histogram analysis of tumors was performed on arterial and portal phase CT images. images. Morphological imaging features and CT texture histogram parameters of G3-NETs and NECs were compared.ResultsThirty-seven patients (21 men, 16 women; mean age, 56 ± 13 [SD] years [range: 28-82 years]) with 37 tumors (mean diameter, 60 ± 46 [SD] mm) were included (CT available for all, MRI for 16/37, 43%). Twenty-three patients (23/37; 62%) had NEC and 14 patients (14/37; 38%) had G3-NET. NECs were larger than G3-NETs (mean, 70 ± 51 [SD] mm [range: 18 - 196 mm] vs. 42 ± 24 [SD] mm [range: 8 - 94 mm], respectively; P = 0.039), with more tumor necrosis (75% vs. 33%, respectively; P = 0.030) and lower attenuation on precontrast (30 ± 4 [SD] HU [range: 25-39 HU] vs. 37 ± 6 [SD] [range: 25-45 HU], respectively; P = 0.002) and on portal venous phase CT images (75 ± 18 [SD] HU [range: 43 - 108 HU] vs. 92 ± 19 [SD] HU [range: 46 - 117 HU], respectively; P = 0.014). Hemorrhagic content on MRI was only observed in NEC (P = 0.007). The mean ADC value was lower in NEC ([1.1 ± 0.1 (SD)] × 10−3 mm2/s [range: (0.91 - 1.3) × 10−3 mm2/s] vs. [1.4 ± 0.2 (SD)] × 10−3 mm2/s [range: (1.1 - 1.6) × 10−3 mm2/s]; P = 0.005). CT histogram analysis showed that NEC were more heterogeneous on portal venous phase images (Entropy-0: 4.7 ± 0.2 [SD] [range: 4.2-5.1] vs. 4.5 ± 0.4 [SD] [range: 3.7-4.9]; P = 0.023).ConclusionPancreatic NECs are larger, more frequently hypoattenuating and more heterogeneous with hemorrhagic content than G3-NET on CT and MRI.  相似文献   
76.
目的 评价中老年人社会资本量表的信效度,探索其在不同健康状况的中老年人群间的区分度。方法 针对已编制的中老年人社会资本量表,采用多阶段分层随机抽样方法,在四川省成都市及泸州市共抽取1 367名50岁及以上中老年居民进行问卷调查。运用Cronbach’s α系数、Pearson相关系数、t检验、探索性因子分析等方法评价量表的信度和效度。结果 1 367名中老年调查对象的社会资本量表总Cronbach’s α系数为0.67,各维度条目与总分的相关系数在0.30~0.79之间,具有良好的信度;探索性因子分析表明,14个条目提取出5个特征根大于1的因子,累积方差贡献率为68.84%;现患慢性疾病的中老年病例组人群的个人社会资本得分、家庭社会资本得分、社团社会资本得分、社区社会资本得分及社会资本总得分均低于未患病的对照人群组,宏观社会资本得分高于对照人群组,且差异均有统计学意义 (均 P<0.01),提示该量表具有较好的区分度。结论 中老年人社会资本量表具有较好的信度和效度,且对不同健康状况的50岁及以上中老年人中有较好的区分度。  相似文献   
77.
妊娠期甲状腺癌的诊治是目前甲状腺疾病诊治的热点和难点问题之一。妊娠期发现甲状腺癌对临床医生和孕妇都是一个极大的挑战,应通过多学科协作,尽快明确诊断,全面、合理的评估孕妇和胎儿的情况,选择最合适的治疗和随诊方式,避免对孕妇和胎儿产生副反应,维持正常孕期,获得最佳的治疗效果。  相似文献   
78.
79.
《中国现代医生》2020,58(4):84-86+90
目的评价西药联合穴位贴敷中西医结合治疗复治肺结核的临床疗效。方法选择本院2017年1月~2018年1月收治的60例复治肺结核患者进行分组研究,全部患者根据治疗方法不同随机分为两组,每组各30例。两组均采取西药进行治疗,采用2HRZE/6HRZ标准化疗方案,实验组同时联合穴位贴敷中西医结合进行治疗,治疗后对比分析两组病灶吸收情况及两组临床症状改善情况。结果实验组病灶恶化9例,其病灶显著吸收率达50.0%,总有效率达70.0%,对照组病灶恶化6例,不变5例,其病灶显著吸收率达33.3%,总有效率达63.3%,两组病灶吸收总有效率组间比较,差异具有显著性(P0.05);实验组的疗效指数治疗6个月后显著高于对照组,组间比较,差异具有显著性(P0.05)。结论西药联合穴位贴敷中西医结合治疗复治肺结核疗效确切,可以显著促进病灶吸收,改善临床症状,安全性好,且还可以扶助人体正气,提高机体免疫力,调节全身状态,以达到治疗目的,是治疗复治肺结核的有效方法之一,值得临床广泛推广和应用。  相似文献   
80.
PurposeFew investigations have examined the production of single restorations using intraoral scanners (IOS). Data on full-arch scans are rare, and data regarding torsion within the entire arch are very sparsely reported. Therefore, the aim of this study was to examine the deviations of torsion and linear distances in full-arch scans of three IOS based on different scanning principles.MethodsA cobalt-chrome-molybdenum alloy master model (CCMM) with four hemispheres was fabricated by laser sintering. The CCMM was digitized using a laboratory scanner (ATOS-Core/GOM) and scanned with three IOS (Omnicam/Sirona(OC); True Definition/3M(TD); TriosII/Cara-Version/Kulzer(TR)). All scan data were exported in a standard STL-file format and were analyzed with GOM Inspect software (V7.5/GOM). Torsion between the right and left side of the arch and linear accuracy (trueness and precision) were evaluated. After normality was confirmed, all data were subjected to parametric statistical analyses.ResultsThe torsion ranged from 0.07 ± 0.03°(OC) to 0.29 ± 0.14°(TD). Pairwise comparisons showed significant differences between the OC and TD scanners and between the TR and TD scanners. The linear distances ranged from 6 ± 5 μm(OC) to 298 ± 317 μm(TD). Significant differences were observed among all investigated IOS (p = 0.05).ConclusionsAlthough the highest torsion was observed for the TD scanner, it is still not clear whether the differences between the IOS are related to the scanning principle or to the scanning algorithm. Due to the high clinical relevance of full-arch restorations, future studies should consider torsion. Regarding linear accuracy, no general difference related to the scanning principles of the IOSs was observed.  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