全文获取类型
收费全文 | 1226篇 |
免费 | 82篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 14篇 |
儿科学 | 47篇 |
妇产科学 | 14篇 |
基础医学 | 224篇 |
口腔科学 | 13篇 |
临床医学 | 162篇 |
内科学 | 222篇 |
皮肤病学 | 10篇 |
神经病学 | 76篇 |
特种医学 | 105篇 |
外科学 | 132篇 |
综合类 | 18篇 |
预防医学 | 44篇 |
眼科学 | 33篇 |
药学 | 152篇 |
肿瘤学 | 61篇 |
出版年
2022年 | 7篇 |
2021年 | 19篇 |
2020年 | 8篇 |
2019年 | 9篇 |
2018年 | 14篇 |
2017年 | 15篇 |
2016年 | 19篇 |
2015年 | 20篇 |
2014年 | 33篇 |
2013年 | 32篇 |
2012年 | 53篇 |
2011年 | 45篇 |
2010年 | 25篇 |
2009年 | 28篇 |
2008年 | 40篇 |
2007年 | 57篇 |
2006年 | 47篇 |
2005年 | 37篇 |
2004年 | 55篇 |
2003年 | 45篇 |
2002年 | 51篇 |
2001年 | 53篇 |
2000年 | 53篇 |
1999年 | 51篇 |
1998年 | 37篇 |
1997年 | 23篇 |
1996年 | 31篇 |
1995年 | 16篇 |
1994年 | 23篇 |
1993年 | 9篇 |
1992年 | 16篇 |
1991年 | 14篇 |
1990年 | 18篇 |
1989年 | 28篇 |
1988年 | 19篇 |
1987年 | 17篇 |
1986年 | 11篇 |
1985年 | 13篇 |
1983年 | 12篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1973年 | 8篇 |
1972年 | 15篇 |
1971年 | 9篇 |
1967年 | 10篇 |
1954年 | 8篇 |
1949年 | 7篇 |
1939年 | 8篇 |
1938年 | 7篇 |
排序方式: 共有1327条查询结果,搜索用时 15 毫秒
51.
目的:制备大鼠在体缺血再灌注模型,观察缺血预处理程序中心肌环磷酸腺苷含量及环磷酸腺苷依赖蛋白激酶活性的变化。方法:实验于2005-03/2006-10在解放军沈阳军区总医院医学实验动物中心和全军心血管研究所实验室完成。实验分组:选用健康雌性SD大鼠36只,根据预适应程序分为第1,2,3次缺血,第1,2,3次再灌注,每一时间点6只大鼠。实验过程:用手术套管法造成左冠状动脉主干缺血及再灌注。所有实验动物在实验程序结束后,取出心脏迅速置液氮保存备用。实验评估:用放射免疫法测环磷酸腺苷水平,生化法测环磷酸腺苷依赖蛋白激酶活性变化。结果:36只大鼠均进入结果分析。①环磷酸腺苷含量:第1次再灌注组低于第1次缺血组[(0.325±0.015),(0.395±0.024)pmol/g,t=6.06,P<0.001],第2次再灌注组低于第2次缺血组[(0.523±0.017),(0.708±0.067)pmol/g,t=6.56,P<0.001],第3次再灌注组低于第3次缺血组[(0.567±0.031),(0.712±0.038)pmol/g,t=7.24,P<0.001]。②环磷酸腺苷依赖蛋白激酶活性:第1次再灌注组低于第1次缺血组[(10.115±1.000),(16.351±0.849)pkat/g,t=11.12,P<0.001],第2次再灌注组低于第2次缺血组[(11.877±2.213),(14.869±0.619)pkat/g,t=3.31,P<0.01],第3次再灌注组低于第3次缺血组[(11.745±0.987),(14.766±0.329)pkat/g,t=7.09,P<0.001]。③缺血预处理程序中心肌环磷酸腺苷含量及环磷酸腺苷依赖蛋白激酶活性随缺血及再灌注呈周期性波动。在5min缺血预处理时表现为明显增高,而在间隔的再灌注程序中恰呈相反改变,有明显下降的趋势。结论:环磷酸腺苷及环磷酸腺苷依赖蛋白激酶的周期性波动变化可能是激发心肌缺血预处理的机制之一,环磷酸腺苷可能在预处理保护作用中起一些作用。 相似文献
52.
股方肌肌骨瓣植入治疗成人股骨头缺血性坏死 总被引:1,自引:0,他引:1
目的:目前成人股骨头缺血性坏死的手术方法较多,但远期疗效大多不肯定。股方肌肌骨瓣植入术可以治疗成人股骨头缺血性坏死,但需验证其近远期疗效。方法:选择2001-01/2007-01铜川市矿务局中心医院骨科收治的股方肌肌骨瓣植入治疗股骨头坏死患者15例(18髋),均知情同意。术中暴露股方肌及其在股骨近端的附着点,于附着点处凿取骨瓣,骨瓣为4cm×1.5cm×1.0cm的长方形,将骨瓣插入股骨头内,远端用可吸收骨钉固定。术后3,6,12,24个月门诊复查拍患髋正位和蛙式位X射线片,根据临床查体和X射线片表现将手术效果分为优、良、差3级。结果:全部患者均获随访,随访时间4~36个月。近期疗效满意,出院时疼痛症状均缓解,未见手术相关并发症。中远期随访结果优10髋,良6髋,差2髋,优良率88.9%。结论:股方肌肌骨瓣植入术治疗成人股骨头缺血性坏死近远期疗效确切,手术操作相对简单。 相似文献
53.
Vogl T Eichler K Zangos S Herzog C Hammerstingl R Balzer J Gholami A 《Journal of cancer research and clinical oncology》2007,133(3):177-184
Purpose To evaluate results in the palliative treatment of patients with liver metastases of uveal malignant melanoma using transarterial
chemoembolization (TACE).
Materials and methods Superselective TACE was repeatedly performed in 12 patients with liver metastases of uveal malignant melanoma. Six patients
presented with solitary liver metastases (6–12 cm in size) and six patients with oligonodular metastases (n ≤ 6). The embolization suspension consisted of a maximum of 10 mg/m2 Mitomycin C, 10 ml Lipiodol, and an injection of 200–450 mg resorbable microspheres for vascular occlusion. In the follow-up,
magnetic resonance imaging was performed in 3-month intervals.
Results The TACE procedure was well tolerated in all patients without any relevant side effects. Three patients responded to TACE
with a size reduction of more than 50% (partial response), five patients with stable disease, and four patients with progressive
disease with an increase in volume of more than 25%. Mean survival following primary tumor treatment was 32.9 months, and
after first embolization 19.5 months. Lower survival rates were recorded for the progressive group (16.5 months).
Conclusion Repeated TACE offers a palliative treatment option in patients with oligonodular liver metastases of uveal malignant melanoma. 相似文献
54.
Large-scale variation among human and great ape genomes determined by array comparative genomic hybridization 总被引:6,自引:1,他引:6 下载免费PDF全文
Locke DP Segraves R Carbone L Archidiacono N Albertson DG Pinkel D Eichler EE 《Genome research》2003,13(3):347-357
Large-scale genomic rearrangements are a major force of evolutionary change and the ascertainment of such events between the human and great ape genomes is fundamental to a complete understanding of the genetic history and evolution of our species. Here, we present the results of an evolutionary analysis utilizing array comparative genomic hybridization (array CGH), measuring copy-number gains and losses among these species. Using an array of 2460 human bacterial artificial chromosomes (BACs) (12% of the genome), we identified a total of 63 sites of putative DNA copy-number variation between humans and the great apes (chimpanzee, bonobo, gorilla, and orangutan). Detailed molecular characterization of a subset of these sites confirmed rearrangements ranging from 40 to at least 175 kb in size. Surprisingly, the majority of variant sites differentiating great ape and human genomes were found within interstitial euchromatin. These data suggest that such large-scale events are not restricted solely to subtelomeric or pericentromeric regions, but also occur within genic regions. In addition, 5/9 of the verified variant sites localized to areas of intrachromosomal segmental duplication within the human genome. On the basis of the frequency of duplication in humans, this represents a 14-fold positional bias. In contrast to previous cytogenetic and comparative mapping studies, these results indicate extensive local repatterning of hominoid chromosomes in euchromatic regions through a duplication-driven mechanism of genome evolution. 相似文献
55.
Laurent Frenzel Rose-Marie Javier Francoise Eichler Goerg Zollner Jean Sibilia 《Joint, bone, spine : revue du rhumatisme》2010,77(2):171-173
Bone metastases are usually seen on imaging studies as lytic lesions and less often as sclerotic or mixed lesions. We report an exceedingly unusual case of breast cancer identified after magnetic resonance imaging showed bone metastases with fluid-fluid levels in the spine and sacrum. Bone images containing fluid-fluid levels are usually solitary abnormalities produced by aneurismal bone cysts. The fluid-fluid level is due to bleeding within the tumor followed by layering of the blood components based on density differences. Only two other cases of bone metastases with multiple fluid-fluid levels have been reported. Although fluid-fluid levels are exceedingly rare, clinicians should be aware that they might indicate a malignancy, particularly when they are multiple. 相似文献
56.
57.
Observations on cyclical variations in the nasal resistance were made using active anterior rhinomanometry. About 80% of 40 healthy individuals showed a nasal cycle with a mean period of 2.5 h. Measurements were made during a 8 h at intervals of 30 min. Quantitative values for the variations of the flow volume V1.5 at 1.5 hPa are given and discussed. 相似文献
58.
Modulation of matrix metalloproteinase and TIMP-1 expression by cytokines in human RPE cells 总被引:10,自引:0,他引:10
Eichler W Friedrichs U Thies A Tratz C Wiedemann P 《Investigative ophthalmology & visual science》2002,43(8):2767-2773
PURPOSE: The balance between matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) is crucial for homeostasis of ocular extracellular matrices. To assess altered MMP activity as a determinant in the migration of human retinal pigment epithelial (RPE) cells, expression characteristics of several MMPs and TIMP-1 in RPE cell cultures were investigated. METHODS: Expression studies were performed with RT-PCR, ELISA, and immunofluorescence analysis. Secretion of MMP-2 was demonstrated by zymography. Migration of cytokine-stimulated RPE cells was evaluated with microporous membranes of permeable chambers. RESULTS: MMP-1, -2, -3, and -9; MT2-MMP; and TIMP-1 were expressed in cultured RPE cells. MMP-2 was detected on the cell surface and in secreted inactive and active forms. TGF-beta(2), IL-1beta, and TNF-alpha enhanced secretion of MMP-1, -2, and -3. TGF-beta(2) also stimulated MT2-MMP cell surface expression and release of TIMP-1. The mRNA levels of MMP-1, -2, and -3 and TIMP-1 were markedly increased by TNF-alpha and TGF-beta(2). MMP-2 mRNA levels were also upregulated by PDGF-BB. Migration of RPE cells stimulated by TGF-beta(2) or PDGF-BB was inhibited in presence of a synthetic MMP inhibitor. CONCLUSIONS: Proinflammatory cytokines and TGF-beta(2) play an important role in the upregulation of expression of MMP-1, -2, and -3 in RPE cells and account for a directional shift in the balance between MMPs and TIMPs. Facilitation of RPE cell migration stimulated by cytokines (i.e., TGF-beta(2) or PDGF-BB) in ocular diseases may be due to increased release of MMPs, in the presence of comparatively lower levels of their inhibitors. 相似文献
59.
60.