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   47082篇
  免费   2849篇
  国内免费   69篇
耳鼻咽喉   735篇
儿科学   2069篇
妇产科学   1107篇
基础医学   5725篇
口腔科学   2212篇
临床医学   4145篇
内科学   10003篇
皮肤病学   1315篇
神经病学   3964篇
特种医学   1493篇
外国民族医学   1篇
外科学   7324篇
综合类   156篇
一般理论   19篇
预防医学   3009篇
眼科学   1098篇
药学   2968篇
中国医学   202篇
肿瘤学   2455篇
  2024年   35篇
  2023年   394篇
  2022年   269篇
  2021年   858篇
  2020年   553篇
  2019年   927篇
  2018年   1574篇
  2017年   1117篇
  2016年   1155篇
  2015年   1092篇
  2014年   1261篇
  2013年   2076篇
  2012年   3419篇
  2011年   3992篇
  2010年   1784篇
  2009年   1112篇
  2008年   3334篇
  2007年   3571篇
  2006年   3378篇
  2005年   3394篇
  2004年   3255篇
  2003年   3026篇
  2002年   2836篇
  2001年   1012篇
  2000年   1206篇
  1999年   692篇
  1998年   274篇
  1997年   213篇
  1996年   192篇
  1995年   172篇
  1994年   138篇
  1993年   122篇
  1992年   159篇
  1991年   146篇
  1990年   131篇
  1989年   120篇
  1988年   104篇
  1987年   91篇
  1986年   63篇
  1985年   62篇
  1984年   70篇
  1983年   66篇
  1982年   64篇
  1981年   46篇
  1980年   51篇
  1979年   48篇
  1978年   39篇
  1977年   50篇
  1976年   33篇
  1973年   33篇
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
71.
In this study we have investigated the negative influence of CO2 and Nd-YAG laser irradiation on rapid cranial regeneration and whether it has any use in certain types of craniosynostosis. Twenty-two newborn rats were used in the study. Both CO2 and Nd-YAG laser irradiation, which was applied to free bony edges after, suturectomies, resulted in a significant decrease in skull regeneration. Histopathological examinations revealed severe degeneration caused by both types of laser energies.  相似文献   
72.
Summary Pedicled temporoparietal fascial flaps have been used extensively in head and neck reconstruction for many years. Also, the fascia has been grafted, and the skin graft transformed into a vascularized pedicled flap (prefabricated temporoparietal fasciocutaneous flap). On the other hand, some authors have used free temporoparietal fascial flaps for defects that require to be filled in lower and upper extremity wounds. In this case, a free prefabricated temporoparietal fascio-chondro-cutaneous flap having only an arterial inflow was used in eyelid reconstruction.Presented at the 14th Congress of Turkish Plastic and Reconstructive Surgery, Ankara, Turkey, October 1992  相似文献   
73.
74.
A nitrogen-specific gas-chromatographic method is described for the quantitative analysis of soluphylline without the need for derivatization or evaporation of solvent, and using only 50 microliters of serum. The analysis is performed isothermally on a silicone stationary phase, 2% SP 2250 DA (Supelco). After a single neutral extraction with ethyl acetate containing the internal standard (beta-hydroxypropyl theophylline), an aliquot of the organic solvent is injected directly into the gas chromatograph. The detector sensitivity (least measurable amount) for soluphylline was 1 ng.  相似文献   
75.
Comparison was made of the aetiology and methods of diagnosis in two series of patients meeting the classic criteria of pyrexia of unknown origin during 1968-1981 and during 1982-1989 seen in the Department of Internal Medicine at La Paz University Hospital, Madrid, Spain. There was a statistically significant decrease in the percentage of infections and an increase in neoplasms and connective tissue disorders in the second series. The percentage of patients diagnosed by laparatomy was similar in both series but the diagnosis yield at laparotomy was greater in the second period. Pyrexia of unknown origin continues to be a condition which can defy clinical expertise in in spite of advances in diagnostic techniques.  相似文献   
76.
A 32-year old woman, with endocarditis caused by Streptococcus mitis, and systolic murmur is presented. The Doppler examination was found a systolic gradient of 150 mmHg. Aortography showed a multiple membranous supravalvular aortic stenosis, with aneurysmal dilatation of the left main coronary artery and circumflex artery, associated with bicuspid aortic valve and mild aortic insufficiency. The patient died suddenly by cardiac arrest in stand by to cardiac surgery. Anatomic comprobation was not possible. The coronary artery anomalies associated with the supravalvular aortic stenosis syndrome are reviewed.  相似文献   
77.
Abstract Alzheimer's disease (AD) is defined pathologically by the presence of β-amyloid plaques, neurofibrillary tangles and extensive neuronal loss. Evidence indicates that increased DNA damage may contribute to neuronal loss in AD. Recently, it has been shown that in AD neurons have a reduced capacity for some types of DNA repair. Polymorphisms in DNA repair genes may be associated with differences in repair efficiency of DNA damage. Variants of several DNA repair genes, including the base excision repair gene XRCC1, have been described previously. We hypothesised that Arg194Trp polymorphism of XRCC1 gene may contribute to genetic susceptibility for AD. In order to test this hypothesis, we investigated Arg194Trp polymorphism at the XRCC1 gene in the DNA samples of 98 patients with AD and 95 healthy subjects. The frequency of the Trp allele was more pronounced among cases (11.2%) compared with controls (5.8%). On combining the homozygous and heterozygous variants of each codon, the variants seemed to be at twofold risk of AD, although the risk estimates were not statistically significant (OR=1.95, 95% CI 0.88–4.34, p=0.09). In addition, the 194Trp allele revealed a borderline significance (OR=2.05, 95% CI 0.96–4.37, p=0.056). According to our results, it may be speculated that the polymorphic variants of XRCC1 codon 194 have a role in the development of AD.  相似文献   
78.
79.
Amartya Sen looks at people's well-being in terms of functioning and freedom, rather than in terms of the amount of goods or services consumed. The capability approach, developed by Sen, deals with what people are able to achieve by using these commodities. Concerning disability, he wrote: “We must take note that a disabled person may not be able to do the many things that an able-bodied individual can, with the same bundle of commodities” [Sen, A. K. (1985). Commodities and capabilities. Oxford: Oxford University Press [1999], p. 7]. The capability approach makes it possible to analyse the economic situation of people with disabilities in a different way. What becomes important is their functioning, i.e. what they are able to achieve within a given context. In fact, the capability set includes not only what a person is effectively able to achieve, but also the potential functionings that he/she can choose. This expresses the degree of freedom that a person with disability benefits from in a given environment. The challenge is therefore to reduce the constraints that the environment adds to a person's impairment in order to expand their capability set and to allow them to live a life which they value. This paper reviews the paradigms that address disability and the ways of assessing a person's capability set within this framework. Achieved functionings are easily measured through cross-sectional surveys, using counterfactual analysis to compare the situations of disabled and non-disabled people. This was done in 2005 in Afghanistan when a national disability survey was carried out on a random sample of households. Measuring detailed capabilities, especially their freedom dimension, is quite complex and requires identifying people's potential choices in an ever-changing environment. This implies a need to extend the philosophical framework and to adopt appropriate statistical methodologies.  相似文献   
80.
The suspicion of a diagnosis of Rett syndrome (RTT) is based on clinical criteria that are often not present in the first two stages of the disease, as many of its symptoms will appear at a later age. This sometimes postpones the genetic diagnosis and an early clinical intervention. We present the case of 19-months-old girl who came to the consultation because of an arrest of psychomotor development noticed 5 months earlier without change in sleep pattern, behavior, or social communication. In the observation of 1 hour videotape, she presented subtle stereotypic movements of the face and hands as well as repetitive dystonic posturing of her limbs. A genetic test confirmed the diagnosis of RTT, showing a truncating mutation in the MECP2 gene (R270X). This case confirms that stereotypic movement anomalies, albeit infrequent and subtle, are already present before the regression stage and while maintaining prehension and that, in addition, repetitive dystonic postures may occur. Recognition of these early movement disorders will improve clinicians' ability to perform an earlier diagnosis of RTT.  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