全文获取类型
收费全文 | 2273篇 |
免费 | 283篇 |
国内免费 | 84篇 |
专业分类
耳鼻咽喉 | 14篇 |
儿科学 | 34篇 |
妇产科学 | 15篇 |
基础医学 | 205篇 |
口腔科学 | 24篇 |
临床医学 | 335篇 |
内科学 | 224篇 |
皮肤病学 | 23篇 |
神经病学 | 58篇 |
特种医学 | 127篇 |
外国民族医学 | 1篇 |
外科学 | 169篇 |
综合类 | 516篇 |
预防医学 | 152篇 |
眼科学 | 24篇 |
药学 | 304篇 |
4篇 | |
中国医学 | 246篇 |
肿瘤学 | 165篇 |
出版年
2024年 | 23篇 |
2023年 | 58篇 |
2022年 | 161篇 |
2021年 | 198篇 |
2020年 | 183篇 |
2019年 | 114篇 |
2018年 | 101篇 |
2017年 | 106篇 |
2016年 | 85篇 |
2015年 | 145篇 |
2014年 | 192篇 |
2013年 | 161篇 |
2012年 | 168篇 |
2011年 | 166篇 |
2010年 | 147篇 |
2009年 | 88篇 |
2008年 | 90篇 |
2007年 | 72篇 |
2006年 | 74篇 |
2005年 | 64篇 |
2004年 | 37篇 |
2003年 | 33篇 |
2002年 | 29篇 |
2001年 | 16篇 |
2000年 | 33篇 |
1999年 | 22篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 15篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 3篇 |
排序方式: 共有2640条查询结果,搜索用时 15 毫秒
11.
脑囊虫病患者脑脊液中一氧化氮及肿瘤坏死因子α水平研究 总被引:2,自引:1,他引:1
目的 探讨脑囊虫病患者各期脑脊液中的一氧化氮 (NO)、肿瘤坏死因子α(TNF α)的变化规律及它们在脑囊虫病中的作用机制。方法 检测 4 9例明确诊断并依据MR分期 ,单发脑实质内囊虫的脑囊虫病患者和 2 0名对照者脑脊液中NO、TNF α水平。结果 NO在脑囊虫病的Ⅰ期显著降低而TNF α水平呈显著升高 ,NO、TNF α于Ⅱ期、Ⅲ期 (整个退变死亡期 )均表现为高水平 ,Ⅳ期恢复正常 ,NO和TNF α存在高度正相关关系。结论 在单发脑实质内囊虫病中NO、TNF α可能参与杀虫作用 ,其免疫调节与杀虫机制存在着动态平衡 ,参与感染控制 相似文献
12.
本文报道用550型全自动生化分析仪,以速率法测定尿NAG活性及本室尿NAG活性的正常参考范围;并对可能影响尿NAG活性的尿PH,尿素浓度等进行了干扰试验及分析。 相似文献
13.
过敏康Ⅱ号胶囊对AsAb阳性大鼠睾丸Bcl-2、Bax表达影响的实验研究 总被引:1,自引:0,他引:1
目的观察过敏康Ⅱ号胶囊对AsAb阳性大鼠睾丸Bcl-2、Bax表达的影响。方法选取健康成年雄性SD大鼠60只,按体重随机分为正常组,模型组,对照组,高、中、低剂量组,每组10只。采用主动免疫法建立血清抗精子抗体(AsAb)阳性动物模型10只,灌胃给药,免疫组化方法观察药物对AsAb阳性大鼠睾丸Bcl-2、Bax表达的影响。结果过敏康Ⅱ号高剂量组睾丸生精细胞和精子Bcl-2表达的平均吸光值显著高于模型组(P〈0.01),而Bax表达的平均吸光值显著低于模型组(P〈0.01)。结论调节睾丸Bcl-2、Bax的表达是过敏康Ⅱ号清除或抑制AsAb起治疗作用的机制之一。 相似文献
14.
在156例先天性心血管畸形标本的观察和测量中,检出先天性三尖瓣畸形25例(16.02%),其中Ebstein's畸形6例,三尖瓣发育不良14例,三尖瓣缺如1例,三尖瓣瓣叶或/和腱索骑跨4例。用测量及比较解剖学的方法探求三尖瓣畸形与其功能的影响。结果显示:Ebstein's畸形和三尖瓣发育不良的心脏构筑都有明显的变化,而且两者存在一定的差异,同时明确了Ebstein's畸形的病理诊断标准和三尖瓣发育不良的分类。 相似文献
15.
16.
Sun X Gulyás M Hjerpe A 《American journal of respiratory cell and molecular biology》2004,30(4):510-518
Human mesothelial cells obtained from benign effusions retain their proliferative capacity and grow uniformly either with a fibroblastic or epithelioid morphology in vitro. These cultures therefore provide a model for the process of mesothelial differentiation in vivo. To study this differentiation, we isolated differentially expressed genes obtained by suppression subtractive hybridization. Of the nine genes found to be overexpressed in fibroblastic mesothelial cells, three are matrix-associated (integrin alpha5, collagen binding protein 2, human cartilage glycoprotein 39), whereas the others are associated with a proliferative cell type (14-3-3 epsilon, plexin B2, N33, and three genes encoding ribosomal elements). Seven of the eight genes upregulated in the epithelioid phenotype are related rather to specialized functions, such as metabolism (aldose reductase, lecithin:cholesterol acyltransferase, ATPase 6), cytoskeletal composition (cytokeratins 7 and 8), and regulation of differentiation (granulin, annexin II). Immunohistochemistry with available antibodies to six of the differentially expressed gene products confirmed the differences also in pleural tissues, where submesothelial cells displayed the fibroblastic markers, whereas surface cells displayed the epithelioid markers. In summary, this approach revealed a pattern of genes coordinately regulated during mesothelial differentiation and suggests that mesothelium may regenerate also by recruiting cells from the submesothelial layer. Some of the gene products may also be useful markers for differentiation and activation in serosal tissues. 相似文献
17.
Effect of aging on neuroglobin expression in rodent brain 总被引:5,自引:0,他引:5
Sun Y Jin K Mao XO Xie L Peel A Childs JT Logvinova A Wang X Greenberg DA 《Neurobiology of aging》2005,26(2):275-278
Neuroglobin (Ngb), a recently discovered O2-binding heme protein related to hemoglobin and myoglobin, protects neurons from hypoxic-ischemic injury in vitro and in vivo. In immunostained mouse brain sections, we found widespread expression of Ngb protein in neurons, but not astrocytes, of several brain regions that are prominently involved in age-related neurodegenerative disorders. Western blots from young adult (3 month), middle-aged (12 month), and aged (24 month) rats showed an age-related decline in Ngb expression in cerebral neocortex, hippocampus, caudate-putamen, and cerebellum. Loss of this neuroprotective protein may have a role in increasing susceptibility to age-related neurological disorders. 相似文献
18.
Sariola H Meng X 《APMIS : acta pathologica, microbiologica, et immunologica Scandinavica》2003,111(1):192-6; discussion 196
Glial-cell-line-derived neurotrophic factor (GDNF) is a distant member of the transforming growth factor superfamily. It binds to and activates a receptor complex consisting of GFR-alpha1 and Ret receptor tyrosine kinase. In testis, GDNF is expressed by Sertoli cells. We have shown by transgenic loss- and gain-of-function mouse models that GDNF regulates the cell fate decision of undifferentiated spermatogonia. In the GDNF +/- mice, the spermatogonia differentiate in excess leading to the depletion of germ cells. In the mice overexpressing GDNF in testes, undifferentiated spermatogonia accumulate in the tubules, no sperm is produced, and the mice are infertile. After a year, the GDNF overexpressing mice frequently (89%) develop testicular tumours, and most of them are bilateral (56%). All these tumours show the same histological pattern. They are composed of round spermatogonial/gonocytic cells with only a scant cytoplasm. The tumours are locally invasive but do not metastasise. They express germ line markers, are positive for alkaline phosphatase, and aneuploid with a triploid peak. Thus, by several histological, molecular, and histochemical characteristics, the GDNF-induced tumours mimic classical seminomas in men, but the precursor lesions are apparently different in mouse and man. 相似文献
19.
目的探讨超声内镜与胃镜对上消化道黏膜下肿瘤的诊断效果。方法选择2015年3月至2018年2月确诊的60例上消化道黏膜下肿瘤患者,均行胃镜检查和超声内镜检查,分析其与病理检查的符合率以及超声内镜检查的回声特点,并记录超声内镜检查的敏感性和特异性。结果以病理检查结果为标准,超声内镜检查的符合率为90.00%,明显高于胃镜检查的73.33%(P <0.05)。超声内镜检查对黏膜肌层肿瘤诊断的敏感性为90.32%,特异性为93.55%;对黏膜下层肿瘤诊断的敏感性为93.33%,特异性为93.75%;对固有肌层肿瘤诊断的敏感性为85.71%,特异性为97.87%。结论与胃镜检查相比,超声内镜在上消化道黏膜下肿瘤中的诊断价值更高,能够对病变的性质、部位及来源作出准确的诊断。 相似文献
20.
乌索酸药理作用研究进展 总被引:5,自引:0,他引:5
乌索酸为五环三萜类药合物,资源广,毒性低、具有广泛的生物活性。有抗肿瘤、抗氧化、抗肝炎、抗炎抑菌,降血脂1抗溃疡等作用。尤其抗肿瘤、抗氧化、抗肝炎作用显,有望成为抗肿瘤,抗肝炎药物。 相似文献