全文获取类型
收费全文 | 2658篇 |
免费 | 288篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 124篇 |
妇产科学 | 39篇 |
基础医学 | 314篇 |
口腔科学 | 100篇 |
临床医学 | 295篇 |
内科学 | 691篇 |
皮肤病学 | 29篇 |
神经病学 | 99篇 |
特种医学 | 321篇 |
外科学 | 348篇 |
综合类 | 38篇 |
一般理论 | 2篇 |
预防医学 | 245篇 |
眼科学 | 15篇 |
药学 | 106篇 |
中国医学 | 3篇 |
肿瘤学 | 176篇 |
出版年
2022年 | 21篇 |
2021年 | 45篇 |
2020年 | 28篇 |
2019年 | 45篇 |
2018年 | 48篇 |
2017年 | 41篇 |
2016年 | 43篇 |
2015年 | 56篇 |
2014年 | 64篇 |
2013年 | 95篇 |
2012年 | 124篇 |
2011年 | 102篇 |
2010年 | 76篇 |
2009年 | 94篇 |
2008年 | 104篇 |
2007年 | 92篇 |
2006年 | 101篇 |
2005年 | 89篇 |
2004年 | 62篇 |
2003年 | 69篇 |
2002年 | 56篇 |
2001年 | 54篇 |
2000年 | 64篇 |
1999年 | 63篇 |
1998年 | 72篇 |
1997年 | 82篇 |
1996年 | 74篇 |
1995年 | 55篇 |
1994年 | 62篇 |
1993年 | 66篇 |
1992年 | 58篇 |
1991年 | 38篇 |
1990年 | 38篇 |
1989年 | 66篇 |
1988年 | 59篇 |
1987年 | 54篇 |
1986年 | 51篇 |
1985年 | 49篇 |
1984年 | 46篇 |
1983年 | 33篇 |
1982年 | 32篇 |
1981年 | 28篇 |
1980年 | 32篇 |
1979年 | 20篇 |
1978年 | 22篇 |
1977年 | 21篇 |
1976年 | 25篇 |
1975年 | 34篇 |
1973年 | 20篇 |
1968年 | 18篇 |
排序方式: 共有2949条查询结果,搜索用时 31 毫秒
31.
Background
Genetic polymorphisms of the TCF7L2 gene are strongly associated with large increments in type 2 diabetes risk in different populations worldwide. In this study, we aimed to confirm the effect of the TCF7L2 polymorphism rs7903146 on diabetes risk in a Brazilian population and to assess the use of this genetic marker in improving diabetes risk prediction in the general population. 相似文献32.
Soluble and membrane-bound forms of brain acetylcholinesterase in Alzheimer''s disease 总被引:1,自引:0,他引:1
Kathleen M. Schegg Leslie S. Harrington Surl Neilsen Richard M. Zweig John H. Peacock 《Neurobiology of aging》1992,13(6):697-704
In order to determine the effect of Alzheimer's disease on the relative distribution of soluble and membrane-bound molecular forms of acetylcholinesterase (AChE) in the brain, postmortem samples (delay interval less than 12 h) were obtained from parietal cortex (Brodmann area 40) and hippocampus as well as the areas containing their respective projection nuclei, i.e., substantia innominata and septal nucleus, in 9 patients with Alzheimer's disease (AD) and 4 normal controls. The monomer (G1), dimer (G2), and tetramer (G4) forms of AChE were examined. In AD compared to controls, significant changes occurred in area 40 and hippocampus but not in the areas containing projection nuclei, and included loss of mean total AChE activity, decrease in the relative percentage of membrane-bound G4, and increase in the relative percentage of soluble G1---G2. Percent of soluble G4 was unaffected in AD brain. In area 40 but not hippocampus a large increase in percent membrane-bound G1-G2 occurred. Thus, these results emphasize that the selective decrease in membrane-bound G4 accounts for the decrease in total G4 activity in AD brain. 相似文献
33.
JE Robb LA Rymaszewski HB Bentley PT Donnan 《Surgical and radiologic anatomy : SRA》1991,13(3):181-185
Summary This study investigated the effect of tilt and observer reliability on radiographic measurements of the position of a prosthetic acetabular cup in seven dry bone pelves using the teardrop as a landmark. Coronal or sagittal tilt of more than five degrees was easily recognisable and there was effectively no observer variation in the measurements up to this limit. In addition, 90 out of 100 randomly selected antero-posterior pelvic radiographs from an outpatient department were not significantly rotated and 93 demonstrated a clearly defined teardrop. Measurements about the teardrop on routine radiographs are therefore sufficiently accurate to allow assessment of prosthetic position.
La valeur du sourcil cotyloidien comme repère d'analyse radiologique
Résumé Cette étude, conduite sur 7 bassins secs, apprécie l'effet de l'inclinaison du bassin sur la qualité de l'analyse radiographique de la position d'une cupule prothétique de hanche en utilisant le sourcil cotyloïdien comme repère. Une inclinaison du bassin dans les plans coronal et sagittal est aisément détectable et il n'existe pas de variation d'analyse entre les différents observateurs en dessous de 5° d'inclinaison. De plus, sur 100 radiographies antéro-postérieures de bassin choisies au hasard dans les dossiers de consultation, 90 avaient été réalisées sans incidence particulièrement adaptée et l'on pouvait repérer facilement le sourcil sur 93% d'entre elles. Les mesures faites sur des radios de routine sont donc suffisamment précises pour permettre l'évaluation de la position d'une prothèse à partir du sourcil cotyloïdien.相似文献
34.
Mohamed HS Ibrahim ME Miller EN Peacock CS Khalil EA Cordell HJ Howson JM El Hassan AM Bereir RE Blackwell JM 《Genes and immunity》2003,4(5):351-355
Longitudinal studies in Sudan show ethnic differences in incidence and clinical phenotypes associated with Leishmania donovani. Immunologically, bias in type 1 vs type 2 cytokine responses is important. To determine whether polymorphisms at IL4/IL9 or IFNGR1 contribute to susceptibility, we examined 59 multicase families of visceral leishmaniasis (VL) with/without post Kala-azar dermal leishmaniasis (PKDL). Multipoint nonparametric analysis (Allegro) linked IL4/IL9 to VL per se (P=0.002). Transmission disequilibrium testing with robust variance estimates confirmed association in the presence of linkage between VL per se and IL4 (P=0.008) but not IL9. Stepwise logistic regression analysis showed both IL4RP2 and IL4RP1 markers contributed significantly to the association, suggesting a common disease-associated haplotype. In contrast, IFNGR1 was linked (P=0.031) and associated (P=0.007) to PKDL but not VL or VL per se. Hence, polymorphism in a type 2 cytokine gene influences underlying susceptibility to VL, whereas IFNGR1 is specifically related to susceptibility to PKDL. 相似文献
35.
Bode G Marchildon P Peacock J Brenner H Rothenbacher D 《Clinical and diagnostic laboratory immunology》2002,9(2):493-495
The prevalence of Helicobacter pylori infection in a population-based sample of 477 children (mean age plus minus standard deviation, 5.8 plus minus 0.5 years) determined by the [(13)C]urea breath test ([(13)C]UBT) was 10.7% (95% confidence interval [CI], 8.1 to 13.8%), and that determined by salivary enzyme-linked immunosorbent assay (ELISA) was 11.9% (95% CI, 9.2 to 15.2%). Compared to the [(13)C]UBT, the sensitivity and specificity of the salivary ELISA were 80.9% (95% CI, 66.3 to 90.4%) and 95.3% (95% CI, 92.7 to 97.1%), respectively. 相似文献
36.
A. Baskerville G. Thomas S. Peacock 《International journal of experimental pathology》1975,56(1):17-27
Groups of mice were immunized against influenza Ao/NWS virus by a single intranasal administration of inactivated homologous virus, by 2 intranasal doses of vaccine separated by an interval of 2 weeks, or by 2 intraperitoneal doses of the same vaccine. When subjected 2 weeks later to a standard challenge of 6 x 10(5) egg infecting units Ao/NWS virus instilled intranasally, mortality fell significantly from 64% in unimmunized mice to 39% in mice given a single intranasal dose of vaccine and to 29% in animals which received double intranasal vaccine. The best protection was conferred by double intraperitoneal immunization, after which mortality was 10%. Immunity waned with time, since the mortality of mice doubly immunized by the respiratory route and challenged 30 weeks later was 49%. Intrapulmonary lymphoid tissue developed in large amounts in a proportion of mice immunized by all methods and challenged after an interval of 2 weeks. Attention is drawn to this reaction as a possible unfavourable consequence of vaccination. There were no lesions in the lungs or central nervous system after immunization without subsequent challenge. The importance of histopathology in vaccine trials in experimental animals is emphasized by the consistently higher detection rate of lesions in lungs by histological examination than by visual inspection alone. 相似文献
37.
38.
Ligand induced internalization of epidermal growth factor receptors by A431 cells decreases at high cell densities in culture. 总被引:1,自引:0,他引:1
Internalization of epidermal growth factor (EGF) receptors by human A431 epidermoid carcinoma cells was studied at various culture densities. The extent of EGF receptor internalization was measured by quantitation of internalized 125I-EGF during incubation at 37 degrees C for 30 min. When cell culture density was below 1 x 10(5) cells/cm2 receptor internalization was active; 30-40% excess moles of ligand over the moles of surface EGF receptors were internalized during this period. However, when culture density increased to above 1.5 x 10(5) cells/cm2 receptor internalization became less extensive, as only 30-50% of ligand bound to the cell surface underwent internalization during 30 min incubation. In parallel with this reduction in receptor internalization, the degradation rate of 35S-methionine labeled EGF receptors was reduced at a high culture density. In contrast with this regulation of receptor internalization, the affinity of EGF receptors for the ligand increased as culture density increased. The extent of EGF-dependent receptor phosphorylation was found to be constant at all culture densities tested. Thus, the observed low level of receptor internalization at high culture densities was not attributable to lower responsiveness of receptors to EGF. These data suggest the presence of an as yet unidentified cell density-dependent mechanism for regulating receptor internalization in cultured A431 cells. 相似文献
39.
40.