全文获取类型
收费全文 | 13151篇 |
免费 | 1610篇 |
国内免费 | 302篇 |
专业分类
耳鼻咽喉 | 62篇 |
儿科学 | 199篇 |
妇产科学 | 133篇 |
基础医学 | 1620篇 |
口腔科学 | 269篇 |
临床医学 | 1114篇 |
内科学 | 2275篇 |
皮肤病学 | 146篇 |
神经病学 | 796篇 |
特种医学 | 338篇 |
外国民族医学 | 2篇 |
外科学 | 639篇 |
综合类 | 1471篇 |
一般理论 | 3篇 |
预防医学 | 3083篇 |
眼科学 | 211篇 |
药学 | 1346篇 |
3篇 | |
中国医学 | 274篇 |
肿瘤学 | 1079篇 |
出版年
2024年 | 27篇 |
2023年 | 267篇 |
2022年 | 337篇 |
2021年 | 621篇 |
2020年 | 551篇 |
2019年 | 521篇 |
2018年 | 469篇 |
2017年 | 544篇 |
2016年 | 522篇 |
2015年 | 612篇 |
2014年 | 947篇 |
2013年 | 1079篇 |
2012年 | 889篇 |
2011年 | 938篇 |
2010年 | 768篇 |
2009年 | 724篇 |
2008年 | 683篇 |
2007年 | 707篇 |
2006年 | 587篇 |
2005年 | 446篇 |
2004年 | 420篇 |
2003年 | 307篇 |
2002年 | 284篇 |
2001年 | 279篇 |
2000年 | 206篇 |
1999年 | 162篇 |
1998年 | 148篇 |
1997年 | 136篇 |
1996年 | 132篇 |
1995年 | 97篇 |
1994年 | 81篇 |
1993年 | 67篇 |
1992年 | 76篇 |
1991年 | 61篇 |
1990年 | 40篇 |
1989年 | 32篇 |
1988年 | 46篇 |
1987年 | 29篇 |
1986年 | 30篇 |
1985年 | 36篇 |
1984年 | 22篇 |
1983年 | 19篇 |
1982年 | 20篇 |
1981年 | 17篇 |
1980年 | 18篇 |
1979年 | 16篇 |
1978年 | 9篇 |
1977年 | 18篇 |
1976年 | 7篇 |
1975年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
61.
Thompson JM Irgens LM Skjaerven R Rasmussen S 《BJOG : an international journal of obstetrics and gynaecology》2007,114(6):715-720
Objective To produce population-based, gender- and gestational-age-specific centile curves for placental weight.
Design Population study.
Setting Medical Birth Registry of Norway
Population All singleton live births in Norway from 1 January 1999 to 31 December 2002.
Methods In a cohort of children born in Norway, placental weights and the ratio of the birthweight to the placental weight were analysed to produce percentile curves.
Main outcome measures Placental weight, birthweight-to-placental weight ratio.
Results Tables and figures are presented for placental percentiles curves according to gestational age and gender. Also, tables and figures are presented for the ratio of birthweight to placental weight.
Conclusions To our knowledge, this is the first time that population percentile curves have been produced for placental weights and hence for the ratio of birthweight to placental weight. These percentile curves may act as a reference for other populations as well until population-specific curves can be produced. 相似文献
Design Population study.
Setting Medical Birth Registry of Norway
Population All singleton live births in Norway from 1 January 1999 to 31 December 2002.
Methods In a cohort of children born in Norway, placental weights and the ratio of the birthweight to the placental weight were analysed to produce percentile curves.
Main outcome measures Placental weight, birthweight-to-placental weight ratio.
Results Tables and figures are presented for placental percentiles curves according to gestational age and gender. Also, tables and figures are presented for the ratio of birthweight to placental weight.
Conclusions To our knowledge, this is the first time that population percentile curves have been produced for placental weights and hence for the ratio of birthweight to placental weight. These percentile curves may act as a reference for other populations as well until population-specific curves can be produced. 相似文献
62.
羁押人员HIV感染状况及行为学调查 总被引:2,自引:0,他引:2
目的了解羁押人员HIV感染现状以及相关高危行为情况,为制定艾滋病防治措施和决策提供科学依据。方法使用描述性研究方法对2381名羁押人员的人群特征以及HIV感染的血清流行病学调查资料进行综合分析。结果共发现HIV抗体阳性3例,阳性率1.26‰;注射吸毒、性乱、有偿供血史的分别占2.18%、30.28%、0.59%。结论羁押人员高危行为发生率较高,应尽快采取健康教育、行为干预和相应监管措施。 相似文献
63.
目的探讨血压正常老年患者和老年高血压患者24h动态血压波动规律及与靶器官损害的关系.方法采用无创伤袖带式动态血压监测仪检测36例中年人(对照组),50例血压正常老年患者,60例老年高血压患者的动态血压.结果血压正常老年患者较中年血压正常者24h动态血压呈杓型曲线的比例明显下降.血压正常老年患者,血压昼夜波动曲线与心、脑、肾损害无相关性.老年高血压患者,血压曲线呈非杓型者比例增高,血压昼夜节律消失较节律正常的高血压患者有更显著的靶器官损害.结论对于非高血压患者,随年龄的增加,血压昼夜节律消失者增多,血压曲线变化与心、脑、肾损害无关,可能与原发病有关.对于高血压患者,血压昼夜节律紊乱可作为靶器官损害的预测因子. 相似文献
64.
Haruo Sagaza 《Geriatrics & Gerontology International》2004,4(S1):S34-S37
Recently the term 'global aging', which refers to the universal trend of aging of the world population, is being widely used. First of all, I will shed some light on this trend of world population aging from the viewpoint of regional populations and their future projections.
Second, I will discuss about the determinants of population aging in the Asia and Oceania region. So far as the region is concerned, it will be divided into three groups of countries according to the level of population aging. The first group is the most advanced aged countries such as Japan, Australia, and New Zealand whose percentage of the elderly aged 65 and over is more than 10% in the year of 2000. The second group is the aging countries such as Korea, Taiwan, Singapore, and China whose percentage of the elderly is between 5 and 10%. and the third group is the remaining countries in this region whose percentage is less than 5%. The demographic aspects of each group are analyzed and the relationships between the fertility reduction and aging are also discussed in the perspectives of the demographic transition.
Third, I will discuss about the consequences of population aging in this region with special reference to Asian developing countries. In this section, I will mention the problems of dependency burden, the so-called population bonus, health expectancy, and social security systems. Fourth, some prominent characteristics concerning the living conditions and norms or attitudes of the elderly will be indicated, and I will also raise such points like family systems, living arrangements, social participation, and Ikigai (the worth of life) peculiar to Asian countries. Fifth and finally, I will touch on the topics of the issues and policies of the aging society. At present the social status of the elderly is improving in Asian countries and it is in the hope that the myth of aging will disappear in the near future. 相似文献
Second, I will discuss about the determinants of population aging in the Asia and Oceania region. So far as the region is concerned, it will be divided into three groups of countries according to the level of population aging. The first group is the most advanced aged countries such as Japan, Australia, and New Zealand whose percentage of the elderly aged 65 and over is more than 10% in the year of 2000. The second group is the aging countries such as Korea, Taiwan, Singapore, and China whose percentage of the elderly is between 5 and 10%. and the third group is the remaining countries in this region whose percentage is less than 5%. The demographic aspects of each group are analyzed and the relationships between the fertility reduction and aging are also discussed in the perspectives of the demographic transition.
Third, I will discuss about the consequences of population aging in this region with special reference to Asian developing countries. In this section, I will mention the problems of dependency burden, the so-called population bonus, health expectancy, and social security systems. Fourth, some prominent characteristics concerning the living conditions and norms or attitudes of the elderly will be indicated, and I will also raise such points like family systems, living arrangements, social participation, and Ikigai (the worth of life) peculiar to Asian countries. Fifth and finally, I will touch on the topics of the issues and policies of the aging society. At present the social status of the elderly is improving in Asian countries and it is in the hope that the myth of aging will disappear in the near future. 相似文献
65.
温州医学院胃癌研究课题组 《温州医学院学报》1992,22(3):132-135
报道温州地区胃癌高发区瑞安塘下的致癌危险因素的调查情况,结果表明它是由多种致癌危险因素的综合影响。作者应用内镜活检在18000例慢性胃病患者中查出癌前病变(高危人群)1132例,经3月~14年活检随访,表明胃癌前病变有一定的可逆转性;癌变率较高的是胃溃疡(GU)+不典型增生(ATP)组、GU+慢性萎缩性胃炎(CAG)组及CAG+ATP组均为4.1%;总癌变率为3.1%。早癌检出率占胃癌总数的48.6%,为门诊早癌检出率的6.8倍。此方法简单、经济实用。 相似文献
66.
Distant consanguineous loops are often unknown or ignored during homozygosity mapping analysis. This may potentially lead to an increased rate of false-positive linkage results. We show that failure to take into account the distant loops may seriously underestimate the degree of consanguinity, especially for people from genetically isolated populations; in 6 Alzheimer's disease (AD) patients the distant loops accounted for 57.7 % of inbreeding on average. Theoretical evaluation showed that ignoring distant loops, which account for 18-75% of inbreeding, inflates the frequency of false positive conclusions substantially in 2-point linkage analysis, up to several hundred times. In multipoint linkage analysis of the 6 AD patients a chromosome-wide "empirical" significance of 5% corresponded to a true false positive rate of 11.1%. We show that converting multiple loops to a hypothetical loop capturing all inbreeding may be a convenient solution to avoid false positive results. When extended genealogic data are not available a hypothetical loop may still be constructed based on genomic data. 相似文献
67.
J. C. W. Mak H. C. M. Leung S. P. Ho F. W. S. Ko A. H. K. Cheung M. S. M. Ip M. M. W. Chan-Yeung 《Clinical and experimental allergy》2006,36(4):440-447
BACKGROUND: Reactive oxygen species may contribute to the pathogenesis of asthma. Functional genetic polymorphisms of antioxidant enzymes, superoxide dismutase (SOD) and catalase are good candidates for asthma susceptibility. OBJECTIVE: To investigate the association of the manganese-containing form of SOD (MnSOD) gene at amino acid position 16 (Val16Ala) and catalase gene in the promoter at A-21T and C-262T polymorphisms and asthma in a Hong Kong Chinese population. METHODS: The association study was conducted in a case-control design in asthma patients (n=251) and healthy controls (n=316) by genotyping. The functional significance was assessed by determining erythrocyte SOD and catalase activity. RESULTS: The Val allele of MnSOD at Val16Ala and the A allele of catalase gene at A-21T were not different between patients and controls, while the C allele of catalase gene at C-262T was found to be significantly different between patients and controls (P=0.033). The less frequent variant of catalase gene (-262T) was found to be protective from the development of asthma in a Hong Kong Chinese non-smoking population (adjusted odds ratio=0.35, 0.15-0.85; P=0.017). Asthma patients had elevated erythrocyte SOD and catalase activities in comparison with healthy controls (P<0.01). However, their activities were not associated with different genotypes within healthy controls or asthma patients. CONCLUSION: This is the first report showing that SOD and catalase functional activities are not associated with their respective genetic polymorphisms but related to the presence of asthma in a Hong Kong Chinese population. 相似文献
68.
对阳城县3646名15岁以上人群吸烟状况分析表明,男性吸烟率63.71%,女性吸烟率0.64%,男女合计吸烟率31.49%,并对不同年龄、职业、文化程度与吸烟率的关系进行了分析。吸烟心理动机:“烟草成瘾”占32.06%,“消遣”占28.48%,“解除疲劳”占16.90%,“交际”占22.56%。吸烟人群的4周患病率和慢性病患病率均高于不吸烟人群,两组差别有显著性(P<0.05,P<0.001)。 相似文献
69.
When excluding haemophilia and von Willebrand disease, coagulation factors deficiencies constitute rare autosomal recessive disorders (<1 in 500,000) of less precisely defined epidemiology. We have reported herein the distribution of these entities in the French Basque Country, a genetic isolate of very old individualization with peculiar biological specificities. The prevalence of these disorders was markedly high, especially, as already shown, factor XI deficiency. This unusual profile needs to be discussed in the view of population genetics. 相似文献
70.
异丙酚及氯胺酮靶控输注全静脉麻醉临床应用 总被引:4,自引:1,他引:3
目的 研究异丙酚复合不同镇痛剂量氯胺酮靶控输注全静脉麻醉临床应用的可行性及对血流动力学、麻醉恢复的影响。方法 择期手术患者 80例 ,分别采用异丙酚 (P组 ,n =16)及复合氯胺酮血药浓度 0 2 0mg/L(PK1组 ,n =16) ,0 40mg/L(PK2 组 ,n =16) ,0 60mg/L(PK3 组 ,n =16)和 0 80mg/L(PK4组 ,n =16)全静脉麻醉 ,采用微机控制Graseby 3 5 0 0输液泵靶控输注异丙酚或氯胺酮 ,连接Aspect-A10 0 0型脑电监护仪监测脑电变化 ,观察两组患者血流动力学改变及麻醉恢复情况。结果 单用异丙酚患者随着异丙酚血药浓度升高脑电双频指数 (BIS)值降低 ,呈明显负相关 (P <0 0 5 ) ,氯胺酮血药浓度从 0 2 0mg/L增至 0 80mg/L ,BIS值无明显变化 (P >0 0 5 )。与P组相比 ,PK1,PK2 ,PK3 ,PK4组异丙酚用量减少约 15 %~ 40 % ,PK4组停药至睁眼时间明显延长 ,其余各组无明显差异 (P >0 0 5 )。术中P ,PK1组收缩压、舒张压升高 ,PK2 ,PK3 ,PK4组无明显改变。术后无躁动、不良回忆等并发症。结论 异丙酚复合镇痛剂量的氯胺酮 (0 40~ 0 60mg/L)靶控输注全静脉麻醉具有血流动力学稳定、减少异丙酚用量、无明显术后并发症等优点。 相似文献