全文获取类型
收费全文 | 55033篇 |
免费 | 4715篇 |
国内免费 | 2610篇 |
专业分类
耳鼻咽喉 | 910篇 |
儿科学 | 1167篇 |
妇产科学 | 350篇 |
基础医学 | 7618篇 |
口腔科学 | 8238篇 |
临床医学 | 4527篇 |
内科学 | 5432篇 |
皮肤病学 | 561篇 |
神经病学 | 1728篇 |
特种医学 | 2330篇 |
外国民族医学 | 24篇 |
外科学 | 10631篇 |
综合类 | 8115篇 |
现状与发展 | 8篇 |
预防医学 | 1733篇 |
眼科学 | 604篇 |
药学 | 3307篇 |
29篇 | |
中国医学 | 1868篇 |
肿瘤学 | 3178篇 |
出版年
2024年 | 124篇 |
2023年 | 818篇 |
2022年 | 1496篇 |
2021年 | 2114篇 |
2020年 | 2070篇 |
2019年 | 1871篇 |
2018年 | 1756篇 |
2017年 | 1872篇 |
2016年 | 1848篇 |
2015年 | 2179篇 |
2014年 | 3390篇 |
2013年 | 4689篇 |
2012年 | 2903篇 |
2011年 | 3439篇 |
2010年 | 2995篇 |
2009年 | 2834篇 |
2008年 | 2805篇 |
2007年 | 2797篇 |
2006年 | 2548篇 |
2005年 | 2375篇 |
2004年 | 2142篇 |
2003年 | 1889篇 |
2002年 | 1536篇 |
2001年 | 1321篇 |
2000年 | 1053篇 |
1999年 | 964篇 |
1998年 | 811篇 |
1997年 | 770篇 |
1996年 | 714篇 |
1995年 | 517篇 |
1994年 | 514篇 |
1993年 | 383篇 |
1992年 | 372篇 |
1991年 | 304篇 |
1990年 | 257篇 |
1989年 | 238篇 |
1988年 | 193篇 |
1987年 | 154篇 |
1986年 | 138篇 |
1985年 | 180篇 |
1984年 | 140篇 |
1983年 | 114篇 |
1982年 | 132篇 |
1981年 | 96篇 |
1980年 | 94篇 |
1979年 | 91篇 |
1978年 | 98篇 |
1977年 | 65篇 |
1976年 | 62篇 |
1975年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Langerhans cell histiocytosis includes three clinical forms of histocytosis X. We describe a disseminated form of Langerhans cell histiocytosis (Letterer-Siwe disease) in monozygotic twins. The twins showed simultaneous onset of disease, almost identical clinical follow-up and findings on cranial CT. The cause of this phenomenon remains unknown. 相似文献
82.
83.
Sacral insufficiency fractures develop over a period of time and show time-dependent changes. We report on 15 CT examinations of 5 patients with early-stage insufficiency fractures of the sacrum. In 4 patients only irregular sclerosis without distinct fracture lines was present in 7 of 8 fractures. Of these 4 patients; 3 exhibited intraosseous gas inclusions in a ventral part of a lateral mass; 5 of 8 fractures disclosed a ventral cortical break. When distinct fracture lines had developed in 1 patient, intraosseous vacuum phenomenon had disappeared. Fracture lines evolve over weeks to months and show central bone absorption. The fractures can heal as demonstrated in 4 of 6 fractures in 3 patients, can persist over 1 year without significant changes or can progress to pseudoarthrosis with bone destruction similar to neuropathic joint disease. Intraosseous vacuum phenomena can persist to this stage. Intraosseous vacuum phenomenon is recognized as a potential finding in the early stage of sacral insufficiency fracture, which also is true for irregular sclerosis and ventral cortical disruption.
Correspondence to: A. Stäbler 相似文献
84.
组织工程化肌腱研究进展 总被引:17,自引:2,他引:15
对组织工程化肌腱领域中目前研究的主要成果进行综述,着重阐述了肌腱细胞外基质替代物、肌腱细胞生物学性质及肌腱细胞与细胞外基质材料复合研究中的主要问题。认为,研制适于肌腱细胞生长、粘附和发挥功能的细胞外基质材料;建立生长、增殖可调控的肌腱细胞系;在模拟体内力学条件下,进行肌腱细胞三维培养,将是研究具有特定修复功能的组织工程化肌腱的重要问题。 相似文献
85.
月骨周围进行性不稳定的腕运动力学研究 总被引:3,自引:0,他引:3
目的探索腕月骨周围进行性不稳定的运动力学变化。方法对14具新鲜冷冻尸体腕关节,用计算机辅助测量了正常腕和各阶段月骨周围不稳定时腕动力肌腱在腕屈伸、尺桡偏时滑动幅度,根据肌腱滑动幅度和关节运动范围计算动力肌腱力臂。结果月骨周围进行性不稳定时屈腕肌腱力臂明显增大,屈指肌腱力臂减小;桡侧腕动力肌腱力臂以增大为主,尺侧肌腱力臂以减小为主。桡侧腕屈肌腱在腕屈伸或尺桡偏时均显著增大。结论腕运动力学变化对月骨周围不稳定的形成、运动力学变化、腕部塌陷起重要起动作用。 相似文献
86.
Tyrosine hydroxylase and serotonin containing cells in embryonic rat rhombencephalon: a whole-mount immunocytochemical study 总被引:5,自引:0,他引:5
Rhombencephala from rat embryos were processed as whole-mounts for immunocytochemical detection of monoaminergic cell populations, using antibodies to tyrosine hydroxylase (TH) and serotonin (5-HT). Specific advantages of the whole-mount technique over the classical serial-section method were that even isolated immunoreactive (IR) cells could be detected easily, and three-dimensional relationships could be ascertained without the need for serial reconstruction. Embryos between embryonic days (E) 12 and 16 (the day following nocturnal mating being considered as E1) were used in this study. Both TH and 5-HT immunoreactivities were already detectable at E12, even in the smallest embryos (crown-rump length: 6 mm), but there was a striking difference in the number and regional distribution of these two types of IR cells. TH was expressed in several cell groups located in the rostral rhombencephalon (the presumed anlage of the A4-7 complex) as well as in the caudal rhombencephalon (the presumed anlagen of groups A1-2 and C1-3), whereas 5-HT was expressed in very few cells located near the rostral border of the rhombencephalon (presumed anlage of the B4-9 complex). Although the three-dimensional distribution of the TH-IR cell groups underwent some modifications during the period studied, its general pattern remained relatively stable after E12. This contrasted with the sequential appearance of the 5-HT-IR cell groups and their spatial transformations during this period. Using the rhombencephalic isthmus as a landmark, we found that conspicuous 5-HT-IR fibre bundles penetrated into the mesencephalon from E13 onwards, but that the 5-HT IR cell bodies were exclusively located caudal to the borderline between the mesencephalon and the rhombencephalon (the rhombencephalic isthmus). We therefore suggest the term "rostral rhombencephalic raphe nuclei" for the rostral 5-HT cell groups instead of "mesencephalic raphe nuclei," which is a misnomer. Close spatial association between TH and 5-HT-IR elements was observed mainly in the caudal rhombencephalon, where 5-HT-IR fibres coursed through an area containing numerous TH-IR cell bodies (the presumed anlagen of groups A1-2 and C1-3). 相似文献
87.
88.
Paramyxoviruses of type 1 (PMV-l) isolated from pigeons were genetically analyzed. A part of the fusion and the matrix protein genes were amplified and sequenced, Typical amino acid sequences associated with virulence were determined at the fusion protein cleavage site in all PMV-1 isolates. All Slovene pigeon PMV-1 strains share high amino acid sequence similarity with other pigeon strains. In the phylogenetic tree, they are clustered together with pigeon PMV-1 isolates with moderate pathogenicity. Phylogenetic analysis obtained from the fusion and the matrix protein gene alignments showed the same branching order. Viruses circulating among pigeons were found to form quite unique lineage of virulent NDV strains. 相似文献
89.
Saidenberg-Kermanac'h N Bessis N Lemeiter D de Vernejoul MC Boissier MC Cohen-Solal M 《Journal of clinical immunology》2004,24(4):370-378
To evaluate the respective action of IL-4, an anti-inflammatory cytokine, and OPG, an inhibitor of bone resorption, on the inflammatory process and the associated bone resorption in collagen-induced arthritis (CIA). After CIA induction, DBA/1 mice were treated with OPG or with IL-4 DBA/1 transfected fibroblasts or both OPG + IL-4. CIA significantly improved in IL-4 groups. OPG had no effect on arthritis clinical scores but histologic scores were reduced in OPG, IL-4, and OPG + IL-4 groups vs. nontreated CIA mice. OPG increased significantly BMD and decreased by 45% D-pyridinolin levels. Moreover association of IL-4 and OPG exerted an additive effect of BMD and resorption marker (-68%). Production of IFN-gamma in the supernatants of spleen cells was reduced in IL-4 treated mice. OPG had a moderate effect on IFN-gamma, but potentiated the inhibitory effect of IL-4. OPG and IL-4 prevent bone loss in CIA-mice model and could have additive effects on IFN-gamma secretion. 相似文献
90.
OBJECTIVE: To examine psychosocial predictors of distress (mood disturbance, perceived stress, caregiver burden) in parents of children undergoing stem cell or bone marrow transplantation (BMT). METHOD: Measures of prior illness experiences, premorbid child behavior problems, family environment, social support, and parental coping behavior were obtained from the resident parents of 151 children prior to the children's admission for BMT. Parents subsequently completed assessments of their mood disturbance, perceived stress, and caregiving burden on a weekly basis through week +6 post-BMT, and then monthly through month +6 post-BMT. RESULTS: Significant changes were observed in parental distress across the course of BMT. After correcting for demographic and medical factors, several significant predictors of parental distress trajectories were identified, including prior parent and patient illness-related distress, premorbid child internalizing behavior problems, the family relationship dimensions of the family environment, and parental avoidant coping behaviors. Multivariable models were developed using a hierarchical modeling approach. The best-fit model accounted for approximately 50% of the variance in parental global distress. CONCLUSIONS: Subgroups of parents at higher risk for increased distress during the acute phase of transplant have been identified. These findings can help target parents who may be in greater need of intervention aimed at reducing transplant-related distress. 相似文献