全文获取类型
收费全文 | 15669篇 |
免费 | 1492篇 |
国内免费 | 229篇 |
专业分类
耳鼻咽喉 | 100篇 |
儿科学 | 1166篇 |
妇产科学 | 1687篇 |
基础医学 | 1372篇 |
口腔科学 | 326篇 |
临床医学 | 1464篇 |
内科学 | 1918篇 |
皮肤病学 | 188篇 |
神经病学 | 1191篇 |
特种医学 | 362篇 |
外国民族医学 | 2篇 |
外科学 | 1023篇 |
综合类 | 1731篇 |
现状与发展 | 1篇 |
一般理论 | 3篇 |
预防医学 | 2409篇 |
眼科学 | 626篇 |
药学 | 820篇 |
14篇 | |
中国医学 | 279篇 |
肿瘤学 | 708篇 |
出版年
2024年 | 42篇 |
2023年 | 270篇 |
2022年 | 560篇 |
2021年 | 795篇 |
2020年 | 714篇 |
2019年 | 681篇 |
2018年 | 607篇 |
2017年 | 702篇 |
2016年 | 761篇 |
2015年 | 612篇 |
2014年 | 1039篇 |
2013年 | 1247篇 |
2012年 | 828篇 |
2011年 | 932篇 |
2010年 | 764篇 |
2009年 | 692篇 |
2008年 | 654篇 |
2007年 | 635篇 |
2006年 | 603篇 |
2005年 | 552篇 |
2004年 | 402篇 |
2003年 | 350篇 |
2002年 | 318篇 |
2001年 | 261篇 |
2000年 | 227篇 |
1999年 | 196篇 |
1998年 | 162篇 |
1997年 | 167篇 |
1996年 | 151篇 |
1995年 | 121篇 |
1994年 | 144篇 |
1993年 | 116篇 |
1992年 | 124篇 |
1991年 | 106篇 |
1990年 | 94篇 |
1989年 | 88篇 |
1988年 | 77篇 |
1987年 | 61篇 |
1986年 | 59篇 |
1985年 | 85篇 |
1984年 | 52篇 |
1983年 | 34篇 |
1982年 | 46篇 |
1981年 | 40篇 |
1980年 | 52篇 |
1979年 | 32篇 |
1978年 | 24篇 |
1977年 | 25篇 |
1976年 | 22篇 |
1975年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
J. R. M. Copeland C. McWilliam M. E. Dewey D. Forshaw R. Shiwach R. T. Abed M. S. Muthu N. Wood 《International journal of geriatric psychiatry》1986,1(1):63-70
A random community sample of 1070 subjects aged over 65 was interviewed by trained non-medical interviewers using the Geriatric Mental State, community version (GMSA). A sub-sample of 126 subjects was selected so as to contain possible early cases of dementia, pseudo-dementia, and normal subjects; and re-interviewed, a mean 1 year and 23 weeks later, by a group of psychiatrists in training. The computer diagnosis AGECAT, based on GMSA applied by non-medical raters, had predicted at initial interview, nine out of twelve cases of dementia at follow-up and five out of nine borderline cases. An Organic/Depression Index may prove useful in predicting which of those cases with early organic levels will eventually develop dementia, depression or recover. 相似文献
32.
AIMS: The objective of this study was to assess apoptotic activity in gestational trophoblastic disease (GTD) and its prognostic value in hydatidiform mole (HM). METHODS AND RESULTS: Expression of the specific caspase cleavage site within cytokeratin 18 was assessed immunohistochemically using the monoclonal antibody M30 CytoDeath in 12 spontaneous abortions, 22 partial and 57 complete HM, eight choriocarcinoma (CCA) and 28 normal placentas. The M30 immunoreactivity occurred predominantly in the syncytiotrophoblasts. A significantly higher M30 index in HM and CCA was found when compared with normal placentas and spontaneous abortions (P < 0.001). The M30 index of those HM which spontaneously regressed was significantly higher than those HM which developed persistent disease requiring chemotherapy (P < 0.001). The M30 index correlated with another apoptotic index previously detected by TdT-mediated dUTP nick-end labelling (TUNEL) (P = 0.007) and the proliferation index assessed by the Ki67 antigen (P = 0.034). CONCLUSIONS: We conclude that apoptosis is important in the pathogenesis of GTD. Assessment of apoptotic activity in HM by the M30 index may be considered as an alternative prognostic indicator for predicting the clinical behaviour. 相似文献
33.
34.
大鼠孤束核内NT-LI成分生后发育和衰老变化的光镜和电镜观察 总被引:1,自引:0,他引:1
用免疫细胞化学和电镜相结合技术,在光镜和电镜水平对生后4天、15天、30天、90天、300天和760天6组大鼠孤束核内神经降压肽样免疫反应(NT-LI)成分的生后发育和衰老变化进行了定量研究。光镜下孤束核内NT-LI胞体和终末主要分布于最后区平面,多见于背侧亚核、内侧亚核和连合核内。电镜下内侧亚核内可见NT-LI胞体、树突、轴突及终末。6组大鼠孤束核内NT-LI细胞均数和内侧亚核内NT-LI终末密度及其突触密度均以生后4天至15天间增长最快,NT-LI细胞数在生后15天达到最高,NT-LI终末及突触密度在生后90天达到最高。三者在生后300天时均明显减少。发育期内侧亚核内NT-LI终末构成的突触以Gray Ⅰ型为主,至老年期则变为Gray Ⅱ型占优势。发育期内侧亚核内以含清亮囊泡伴颗粒囊泡的NT-LI终末为主,老年期此类终末明显减少。只含清亮囊泡的NT-LI终末从生后至老年变化不明显。 相似文献
35.
We report an exceptional case of melanotic neuro-ectodermal tumor of infancy (MNTI) occurring in the soft tissue of the left thigh of a 6-month-old female infant. The tumor consisted mainly of small round cells (neuroblasts) arranged in cords and nests that were separated by broad fibrovascular areas. In addition, there were a few medium-sized tumor cells containing melanin pigment (melano-cytic cells) that in electron microscopy contained melanosomes as well as tonofilaments. Both tumor cell types immunostained for neuron-specific enolase (NSE) and vimentin, and the melanocytic cells reacted additionally with the antikeratin antibody KL1. Within the tumor stroma, neurofilament- and S-100-protein-positive neural cells and vimentin- and desmin-positive myofibroblasts were seen. Although densecore granules were demonstrated ultrastructurally in some neuroblasts, no immunostaining for chromogranin A, Leu-7, serotonin, or regulatory peptides was found. MNTI located in an extremity can be confused with malignant small round and blue cell tumors of childhood. The distinction between MNTI and these tumors is of clinical significance because MNTI, in most cases, is a benign tumor that, in contrast to the latter, can be cured by complete excision. The presence of a biphasic cell population with neuroblasts and melanocytic cells must be considered the main diagnostic feature of MNTI. 相似文献
36.
As an alternative to genetic theories of handedness, some theorists have offered an environmental mechanism, associated with birth stress, for the appearance of left-handedness. They suggest that brain damage as a result of birth difficulties can lead to a switch in hand preference from the right side to the left side. Consequently, one should find more left-handers in groups where the probability of the occurrence of birth stress is greater. Three studies are presented which explore the laterality of not only hand but also foot, eye, and ear, in a total of 5161 individuals, in an attempt to assess any relationship to birth stress. Maternal age seems to predict deviations from dextrality, dependent on the sex of the offspring, while paternal age and birth order do not. The use of a direct measure of conditions predisposing toward birth stress suggests that these results depend on prenatal or perinatal environmental trauma rather than chromosomal factors.This research was supported by grants from the Medical Research Council of Canada and from the Natural Sciences and Engineering Research Council of Canada, and represents an equal and shared contribution of both authors. 相似文献
37.
Advances in sequencing and genotyping technologies over the last decade have enabled geneticists to easily characterize genetic variation at the nucleotide level. Hundreds of genes harboring mutations associated with genetic disease have now been identified by positional cloning. Using variation at closely linked genetic markers, it is possible to predict the times in the past at which particular mutations arose. Such studies suggest that many of the rare mutations underlying human genetic disorders are relatively young. Studies of variation at genetic markers linked to particular mutations can provide insights into human geographic history, and historical patterns of natural selection and disease, that are not available from other sources. We review two approaches for estimating allele age using variation at linked genetic markers. A phylogenetic approach aims to reconstruct the gene tree underlying a sample of chromosomes carrying a particular mutation, obtaining a “direct” estimate of allele age from the age of the root of this tree. A population genetic approach relies on models of demography, mutation, and/or recombination to estimate allele age without explicitly reconstructing the gene tree. Phylogenetic methods are best suited for studies of ancient mutations, while population genetic methods are better suited for studies of recent mutations. Methods that rely on recombination to infer the ages of alleles can be fine‐tuned by choosing linked markers at optimal map distances to maximize the information available about allele age. A limitation of methods that rely on recombination is the frequent lack of a fine‐scale linkage map. Maximum likelihood and Bayesian methods for estimating allele age that rely on intensive numerical computation are described, as well as “composite” likelihood and moment‐based methods that lead to simple estimators. The former provide more accurate estimates (particularly for large samples of chromosomes) and should be employed if computationally practical. Hum Mutat 18:87–100, 2001. © 2001 Wiley‐Liss, Inc. 相似文献
38.
J Halldin 《Acta psychiatrica Scandinavica》1984,69(6):503-518
The principal reason for this epidemiological study was the lack of psychiatric morbidity studies in a predominantly urban population, by psychiatrists in direct interviews. The psychiatric examination, covering 1970-71, included a representative selection of 2,283 persons, 18-65 years old from "former" Stockholm County, and the 12-month prevalence of mental disorders was measured. The total of non-participants was 12%. Forty-seven percent had a psychiatric diagnosis - significantly more women (54%) than men (40%). Excluding the psychosomatic diagnoses, 31% of the population received a psychiatric diagnosis, which agrees closely with other contemporary studies of mental disorder in the Nordic countries. The primary diagnoses were: neuroses 26%, psychosomatic diagnoses 16%, schizophrenic/paranoid conditions or other psychoses 0.6%, affective disorders 0.2%, psychoorganic syndromes 1.2%, psychopathy 0.2%, character neurosis 1%, drug dependence 0.2% (as a primary or a secondary diagnosis 0.6%), alcoholism 1.4% (as a primary or a secondary diagnosis 3.1%) and mental retardation 0.4% (as a primary or a secondary diagnosis 0.8%). 相似文献
39.
40.
Calogera Pisano Daniele Polisano Carmela Rita Balistreri Claudia Altieri Paolo Nardi Fabio Bertoldo Daniele Trombetti Laura Asta Maria Sabrina Ferrante Dario Buioni Calogero Foti Giovanni Ruvolo 《Nutrients》2021,13(2)
Frailty is the major expression of accelerated aging and describes a decreased resistance to stressors, and consequently an increased vulnerability to additional diseases in elderly people. The vascular aging related to frail phenotype reflects the high susceptibility for cardiovascular diseases and negative postoperative outcomes after cardiac surgery. Sarcopenia can be considered a biological substrate of physical frailty. Malnutrition and physical inactivity play a key role in the pathogenesis of sarcopenia. We searched on Medline (PubMed) and Scopus for relevant literature published over the last 10 years and analyzed the strong correlation between frailty, sarcopenia and cardiovascular diseases in elderly patient. In our opinion, a right food intake and moderate intensity resistance exercise are mandatory in order to better prepare patients undergoing cardiac operation. 相似文献