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   40901篇
  免费   3555篇
  国内免费   2708篇
耳鼻咽喉   393篇
儿科学   440篇
妇产科学   223篇
基础医学   3486篇
口腔科学   883篇
临床医学   4569篇
内科学   4735篇
皮肤病学   432篇
神经病学   2004篇
特种医学   1997篇
外国民族医学   22篇
外科学   4865篇
综合类   8941篇
现状与发展   10篇
一般理论   11篇
预防医学   3291篇
眼科学   569篇
药学   4454篇
  43篇
中国医学   2909篇
肿瘤学   2887篇
  2024年   136篇
  2023年   487篇
  2022年   1258篇
  2021年   1583篇
  2020年   1355篇
  2019年   1037篇
  2018年   1104篇
  2017年   1158篇
  2016年   1047篇
  2015年   1748篇
  2014年   2268篇
  2013年   2470篇
  2012年   3534篇
  2011年   3848篇
  2010年   2981篇
  2009年   2617篇
  2008年   2818篇
  2007年   2751篇
  2006年   2507篇
  2005年   2235篇
  2004年   1618篇
  2003年   1486篇
  2002年   1180篇
  2001年   857篇
  2000年   724篇
  1999年   547篇
  1998年   293篇
  1997年   283篇
  1996年   209篇
  1995年   186篇
  1994年   161篇
  1993年   96篇
  1992年   93篇
  1991年   91篇
  1990年   93篇
  1989年   58篇
  1988年   37篇
  1987年   36篇
  1986年   52篇
  1985年   35篇
  1984年   16篇
  1983年   11篇
  1982年   7篇
  1981年   10篇
  1979年   4篇
  1974年   3篇
  1973年   5篇
  1972年   4篇
  1970年   7篇
  1968年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
We examined the effect of a new xanthine derivative, HWA448, on antigen-induced bronchoconstriction in actively sensitized guinea pigs. Guinea pigs were sensitized by intraperitoneal injection of bovine serum albumin (BSA) on two occasions, separated by 10 days. Two weeks after the second injection, the animal was placed in a two-chambered whole body plethysmograph and specific airway resistance (SRaw) was monitored for 10 min after an aerosol inhalation of BSA. HWA448 prevented the increase in SRaw after challenge (at 5 and 20 mg/kg i.p.). Aminophylline also prevented the increase in SRaw at 20 mg/kg, but not at a 5-mg/kg dose. The concentration of HWA448, which produced 50% relaxation of the tracheal rings constricted with 0.1 mM of histamine, was 49.9 microM as compared with 18.2 microM in aminophylline. HWA448 has a protective effect on antigen-induced bronchoconstriction in guinea pigs and may be a useful agent in the therapy of bronchial asthma.  相似文献   
32.
目的:探讨HIE患者血中6-keto-PGF1α、NSE水平变化及临床意义.方法:用RIA检测89例HIE患者和32例正常新生儿血中6-keto-PGF1α、NSE水平变化.结果:HIE轻、中、重度组6-keto-PGF1α水平与正常对照组比较,均存在显著性差异(p<0.01),HIE患者轻度组NSE水平与对照组比较无显著性差异(p>0.05),中、重度组NSE水平与对照组比较存在显著性差异(p<0.01),6-keto-PGF1α、NSE二组血中浓度上升与HIE程度呈正相关.结论:HIE患者中6-keto-PGF1α、NSE水平检测,对判断HIE的脑损伤程度、治疗、预后观察,具有重要临床意义和应用价值.  相似文献   
33.
Xie  Shitong  Wu  Jing  Chen  Gang 《Quality of life research》2022,31(9):2791-2803
Quality of Life Research - To evaluate and compare the test–retest reliability of discrete choice experiments with duration (DCETTO) and time trade-off (TTO) in the Chinese SF-6Dv2 valuation...  相似文献   
34.
中药治疗脂肪肝57例临床体会   总被引:1,自引:0,他引:1  
1 临床资料1 .1 一般资料 共 57例 ,其中男 42例 ,女 1 5例 ,年龄最小 2 9岁 ,最大 69岁 ,病程 1个月~ 8年。脂肪肝诊断分轻、中、重三度 ,57例中重度脂肪肝 2 5例 ,中度脂肪肝 32例 ,未将轻度脂肪肝患者纳入观察病例中。伴有糖尿病者 8例 ,有肝炎病史 1 2例 ,胃炎病史 32例 ,血脂升高者 47例 ,43例患者有长期嗜酒的习惯。1 .2 病例纳入条件 共 57例患者均具备以下条件 :(一 )临床表现 :乏力 ,纳差 ,右上腹不适 ,胀闷或胀痛 ,可伴腹胀 ,肋下可及肝脏或未及。 (二 )均有肝功能异常。 (三 ) B超或 CT检查均呈典型的脂肪肝表现 ,且按 B…  相似文献   
35.
医学期刊上刊载的论文多数包含统计学分析。统计学方法的正确运用对医学科研论文的质量是至关重要的。然而,目前发表的许多论文在统计学方面存在着不同程度的缺陷。本文作者尝试为医学期刊稿件的作者们提供一个统计学方面的参考,希望能对提高医学期刊稿件的统计学水平有所裨益。   1 材料与方法部分   1.1 统计设计    1.1.1 一般原则 投往医学期刊的论文多数是研究工作的总结、概括和升华。统计设计是提高论文质量的必要前提。只有缜密的统计设计才能引导出有说服力的研究结论。可以说,如果一篇稿件的统计设计不合理或存在明显缺陷,不必去阅读论文的其余部分,编辑们就有足够的理由不予采用。在材料与方法部分,作者应提供有关统计设计的所有必要信息。这里“必要”的标准是应使读者能够根据这些信息,按照作者所报告的作法(需保密的技术和数据除外)重复该项研究。这些信息应包括:统计研究设计的名称和主要做法;观察单位的类型、采用或排除的条件;样本来源与获取(如抽样)方法;观察单位分组方法;样本大小与为什么采用这样数量的样本;观察指标的类型与获取数据(观测)的方法;不同类型(调查或临床实验等)的研究,还需要一定的附加信息。  相似文献   
36.
Purpose: As COVID-19 spreads globally and affects people''s health, there are concerns that the pandemic and control policies may have psychological effects on young people (age from 17 to 35 years). This psychological impact might vary in different countries, and thus we compared the prevalence of selfreported psychological distress, loneliness and posttraumatic stress symptoms (PTSS) among young people in the United Kingdom (UK) and China at the beginning of the COVID-19 pandemic. Methods: Data of this study came from two sources. One source was the first wave of COVID-19 study in Understanding Society, a special wave of the UK household longitudinal study, which provided the highquality, national-wide representative panel data. The sample comprised 1054 young people. The other source was an online survey on the mental health of 1003 young people from Shanghai, a highly developed area in China. The questionnaire included questions on the prevalence of common mental disorders (cut-off score ≥ 4), loneliness and potential PTSS (cut-off ≥ 33). Univariable analyses were conducted to test the differences in the self-reported prevalence of psychological distress and loneliness between the two groups. Multivariable logistic regression analyses were run to explore the predictors of psychological distress and loneliness among all the young people from England and Shanghai. Results: Among the samples with self-reported psychological distress, the UK sample accounted for 34.4% (n = 1054) and the Chinese sample accounted for 14.1% (n = 1003). The difference between the two groups was statistically significant (p < 0.001). Additionally, 57.1% of people in the UK and 46.7% in China reported that they sometimes or often felt lonely, of which the difference is statistically significant (p < 0.001). Regression analysis of the entire samples showed that nationality, gender, psychotherapy and loneliness were significant predictors of 12-item General Health Questionnaire scores, while the variables of age and living alone were not. Significant predictors of self-reported loneliness were the nationality, gender, age, living alone and psychotherapy. In China, 123 (12.3%) young people, 49 men (11.3%) and 74 women (13.0%), met the criteria of PTSS symptoms (cut-off scores ≥ 33). These scores were only collected in China. Conclusion: This evidence suggests that mental health and loneliness reported by young people were lower in China than that in the UK during the studied period. More research is needed to understand these differences. If the differential negative psychological impacts are confirmed, country-specific measures of prevention and intervention should be adopted to improve the mental health of young people under the ongoing impact of the pandemic.  相似文献   
37.
近年来,甲状腺疾病的发病率逐年上升,其中青年女性患者占较大比例.随着年轻患者对美容的要求提高,多种入路的内镜甲状腺手术已广泛成功开展.这些术式尽管避免了在颈部做切口,并取得了较好的美容效果,但不可避免地在其他部位留下切口瘢痕.经口入路手术被认为是真正无痕的手术,具有更好的美容效果,随着近年来达芬奇手术系统的不断完善,经口入路机器人甲状腺手术也取得较大发展.与其他术式相比,经口入路机器人甲状腺手术具有多种优势,如提供中线入路、最低程度地减少组织损伤、3D高清放大视野、手臂震颤过滤及7个自由度Endo-wrist等.因此,本综述对近年来经口机器人甲状腺手术的研究进展进行总结,为临床甲状腺疾病的治疗提供学习借鉴.  相似文献   
38.
Soil microbial activities and carbon and nitrogen fixation   总被引:5,自引:0,他引:5  
Soil microbial activity that reflects microbiological processes of soil microorganisms is the potential indicator of soil quality, as plants rely on soil microorganisms to mineralize organic nutrients for growth and development. Soil microorganisms also process plant litter and residues into soil organic matter, a direct and stable reservoir of carbon and nitrogen that consists of living and dead organic materials subject to rapid biological decomposition. In natural systems, the action of soil microorganisms is a major determinant of efficient nutrient cycling. This paper reviews the current state of knowledge on the fate of soil microorganisms in terms of carbon and nitrogen fixation.  相似文献   
39.
Morphological typing of argyrophilic nucleolar organizer regions (AgNOR) in 300 caws of malignant tumors and 140 cams of benign lesions was analyzed and five morphological types of ApNOR were described in detail. In malignant tumors, the diffuse type (78%) was the most frequently seen, and in benign lesions, the nucleolar type (92.85%); the difference was thus highly significant (P < 0.001). The intranucleolar and aggregate types were not observed in benign lesions. There was no obvious difference in the proportion of the mixed type in benign and malignant lesions (P > 0.05). The relationship between grade of malignancy and morphological typing of AgNOR and its clinical significance are discussed.  相似文献   
40.
本文对鄂西自治州一市二县三所医院近八年来(1980年元月~1987年12月)成人USD住院患者1592例的构成比作了回顾性调查分析.结果表明:USD患者占同期住院总人数的3.90%,其常见病种依次为尿路结石,尿路感染,慢性肾炎.急性肾炎、肾结核,慢性肾衰和肾病综合征;上尿路结石病人数有逐年上升趋势,且右侧显著高于左侧(P<0.001);慢性肾衰的病人数每隔1~2年有突然增高现象,1987年比1980年增加了四倍;急性肾炎和肾结核占有较大比例,肾结核为慢性肾衰病因的第三位.这些均为本组USD的临床流行病学特点.作者对各常见病种的特点进行了讨论.  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