全文获取类型
收费全文 | 234604篇 |
免费 | 21490篇 |
国内免费 | 12227篇 |
专业分类
耳鼻咽喉 | 2445篇 |
儿科学 | 3038篇 |
妇产科学 | 3423篇 |
基础医学 | 30149篇 |
口腔科学 | 4076篇 |
临床医学 | 28813篇 |
内科学 | 37163篇 |
皮肤病学 | 3867篇 |
神经病学 | 14194篇 |
特种医学 | 9351篇 |
外国民族医学 | 97篇 |
外科学 | 24830篇 |
综合类 | 30143篇 |
现状与发展 | 40篇 |
一般理论 | 38篇 |
预防医学 | 15620篇 |
眼科学 | 6135篇 |
药学 | 24070篇 |
189篇 | |
中国医学 | 11343篇 |
肿瘤学 | 19297篇 |
出版年
2024年 | 766篇 |
2023年 | 3297篇 |
2022年 | 8654篇 |
2021年 | 11229篇 |
2020年 | 8120篇 |
2019年 | 7476篇 |
2018年 | 7958篇 |
2017年 | 7111篇 |
2016年 | 7188篇 |
2015年 | 10655篇 |
2014年 | 12880篇 |
2013年 | 12483篇 |
2012年 | 18130篇 |
2011年 | 19159篇 |
2010年 | 12122篇 |
2009年 | 9460篇 |
2008年 | 12778篇 |
2007年 | 12241篇 |
2006年 | 11626篇 |
2005年 | 11161篇 |
2004年 | 7709篇 |
2003年 | 6893篇 |
2002年 | 5899篇 |
2001年 | 4662篇 |
2000年 | 4817篇 |
1999年 | 4723篇 |
1998年 | 2684篇 |
1997年 | 2698篇 |
1996年 | 2082篇 |
1995年 | 2033篇 |
1994年 | 1762篇 |
1993年 | 1179篇 |
1992年 | 1907篇 |
1991年 | 1769篇 |
1990年 | 1467篇 |
1989年 | 1468篇 |
1988年 | 1355篇 |
1987年 | 1223篇 |
1986年 | 977篇 |
1985年 | 915篇 |
1984年 | 602篇 |
1983年 | 505篇 |
1982年 | 339篇 |
1981年 | 348篇 |
1980年 | 284篇 |
1979年 | 422篇 |
1978年 | 315篇 |
1977年 | 240篇 |
1974年 | 252篇 |
1973年 | 259篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
31.
Facial reanimation after acoustic neuroma excision is currently accomplished using a variety of surgical techniques. A multi-institutional survey of patient perceptions of facial reanimation success was accomplished by mailing a questionnaire to 809 randomly selected members of the Acoustic Neuroma Association. Four hundred sixty patients who underwent 296 reanimation procedures responded. Facial to hypoglossal nerve anastomosis, tarsorrhaphy, and upper eyelid implants were most frequently performed. The patient's estimations of initial deficit, spontaneous recovery, and overall satisfaction with the reanimation procedures are discussed. 相似文献
32.
Birth weight on 12,644 singleton infants from 6,196 sibships born in Maryland between 1980 and 1984 were used to estimate the effects of nine maternal and infant covariates on the sibship correlation in birth weight. Assuming a homogeneous correlation across all families, the estimated intraclass correlation was 0.4664 (+/- 0.0099). This high sibship correlation makes it possible to predict, with reasonable accuracy, the birth weight of a child given information on previous sibs, as well as covariates on the mother and/or infant pertinent to a given pregnancy. The reduction in variance associated with incorporating information on the nine covariates used here was approximately equal to that obtained by conditioning on a single previous sib. Testing for heterogeneity in correlation among different groups of families showed that a crude measure of parity (first live birth vs. other), time between births, mother's marital status, and maternal age at the birth of the last child significantly influenced the sibship correlation in birth weight. 相似文献
33.
34.
棕榈油对成人血脂和血小板功能的影响 总被引:3,自引:0,他引:3
报道了棕榈油(PA),花生油(PE)对血清总胆固醇水平(TC)在5.5~7.0mmol/L的受试者血脂和血小板功能的影响。51名受试者(男31人,女20人,年龄30~66岁之间)分为两组,一组男15人,女11人,称PE组;另一组男16人女9人,称PA组,预备期3周,膳食以当地日常食用的花生油烹调,实验期6周。PA组受试者食用以棕榈油烹调的实验膳;PE组受试者仍食花生油烹调的膳食。脂肪约占膳食能量的30%,其中60%~65%来自实验油。实验结果表明:与起始值相比,6周末PA组受试者血清TC,低密度脂蛋白胆固醇(LDL-C)和总胆固醇与高密度脂蛋白胆固醇比值(TC/HDL-C)显著下降,血浆血栓素B2(TXB2)/6-酮前列环素F1α、(6-keto-PGF1α)比值显著下降,全血血小板聚集率未见显著变化。PE组受试者的血脂、血浆TXB2、6-keto-PGF1α及全血血小板聚集率等指标均未出现显著变化。提示,棕榈油作为我国居民家庭烹调用油并不会增加发生心血管疾病的危险。 相似文献
35.
对13例体外循环病人进行了观察,发现体外循环后TXB2/6-keto-PGF1α显著增高,表明体外循环使血小板受损,而血小板受损是体外循环后失血的主要原因之一。 相似文献
36.
放射性肝纤维化过程的定量研究 总被引:6,自引:0,他引:6
经^60Coγ线照射大鼠肝区,通过光镜、电镜和图像分析仪、宣研究了照后1年肝脏的病理改变。结果表明,30Gy组在照射后1年内逐渐发生了放射性肝纤维化病变。在肝纤维化发生过程中,肝细胞内糖原颗凿含量进行性减少,间质中胶原纤维含量进行性增加,网状纤维于照射1-3个月呈进行性增加。 相似文献
37.
分析43例烧伤初期Ⅱ°创面演变为临床Ⅲ°烧伤创面的病人资料,发现演变多发生在伤后第1~21天,发生的原因主要与清创、休克及并发症有关。因此,除进一步减少创面损伤外,应注意提高病人的机体抵抗力,处理好饶伤初期Ⅱ°创面。 相似文献
38.
目的 检测并比较心肌梗死急性期不同时间点,β2自身抗体阳性组与阴性组,患者血清中Fas/APO-1水平差异,了解β2自身抗体对Fas/APO-1的影响。方法 41例急性心肌梗死患者,分别于发病24h、7天、2~4周时取血,采用ELISA的方法,检测血清中β2自身抗体的阳性率以及Fas/APO-1的水平;另外取34位性别、年龄匹配的健康人的血同法检测Fas/APO-1作为对照。结果心肌梗死急性期Fas/APO-1的水平均高于对照组(P〈0.05),以梗死后24hFas/APO-1的水平为最高;心肌梗死急性期不同时间点,β2自身抗体阳性组Fas/APO-1的水平均高于阴性组,但两组的结果差异无显著性(P〉0.05)。结论 血清Fas/APO-1水平可以在一定程度上反映心肌细胞凋亡的变化趋势,β2自身抗体对Fas/APO-1的确切影响,有待更大规模的实验来证实。 相似文献
39.
Dopamine differentially regulates dynorphin, substance P, and enkephalin expression in striatal neurons: in situ hybridization histochemical analysis. 总被引:14,自引:0,他引:14
Dopamine regulation of the levels of dynorphin, enkephalin, and substance P messenger RNAs in rat striatal neurons was analyzed with in situ hybridization histochemistry (ISHH). Relative levels of peptide mRNA expression in the patch and matrix compartments of the dorsolateral striatum were compared among control rats, rats treated for 10 d with apomorphine, rats with unilateral 6-hydroxydopamine (6-OHDA) lesions of the nigrostriatal dopaminergic system, and rats with nigrostriatal dopaminergic lesions followed 2 weeks later by 10 d of apomorphine treatment. Image analysis of ISHH labeling demonstrated that the number of neurons expressing each peptide mRNA remained constant, whereas the relative level of peptide mRNA per neuron changed significantly, depending on the experimental treatment. Dynorphin mRNA expression increased following chronic apomorphine treatment: striatal patch neurons increased to an average of 100% above control values, whereas striatal matrix neurons showed only a 25% increase. Dynorphin mRNA expression decreased following 6-OHDA lesions: patch neurons showed an average 75% reduction in expression, whereas matrix neurons showed no significant change. In animals with 6-OHDA lesions followed by apomorphine treatment, both patch and matrix neurons showed an average increase in dynorphin expression of 300% above control levels. Changes in dynorphin mRNA levels with these treatments were matched by qualitative changes in dynorphin immunoreactivity both in the striatum and in striatonigral terminals in the substantia nigra. Neither substance P nor enkephalin mRNA levels showed a significant difference between the striatal patch and matrix compartments in any experimental condition (in the dorsolateral striatum). Substance P mRNA expression was increased an average of 50% after 10 d of apomorphine treatment and showed an average decrease of 75% following 6-OHDA lesions of the mesostriatal system. There was no significant change in the expression of substance P mRNA in striatal neurons compared to control values in rats with combined 6-OHDA lesion and apomorphine treatment. Enkephalin mRNA expression was not significantly altered by chronic apomorphine treatment but showed an average increase per cell of some 130% above control levels following 6-OHDA-induced lesions of the mesostriatal system. In animals with a 6-OHDA lesion and apomorphine treatment, enkephalin mRNA was also elevated but not significantly above the levels produced by the lesions alone. These data show that the expression of dynorphin, enkephalin, and substance P is differentially regulated by the mesostriatal dopaminergic system and, further, suggests that the mechanisms by which this regulation occurs may be different for the 3 peptide families. 相似文献
40.
OBJECTIVE: To understand the role of nasal mucous epithelial cells to hypoxia in early stage of nasal polyps(NP) formation. METHODS: Epithelial cells of NP and inferior turbinate (IT) were cultured without serum under normal oxygen and hypoxia, and stimulus of inflammatory cytokines. Erythropoietin (EPO) was regarded as hypoxia mark, and expression of vascular endothelial growth factor(VEGF) mRNA and protein derived from epithelial cells were detected respectively by in situ hybridization and ELISA. RESULTS: 1. Under hypoxia, EPO mRNA was expressed intensely in epithelial cells from NP and IT, and there was no significant difference between both of them. This result suggested that EPO might be regarded as a hypoxic mark. 2. The ability of producing VEGF mRNA increased with cytokines stimulation, especially under hypoxia. Protein level of VEGF from epithelial cells of NP and IT increased with cytokines stimulation, especially in hypoxia and was time-dependent. CONCLUSION: Epithelial cells actively produce vast VEGF under hypoxia. The VEGF induced by hypoxia of the mucosa in middle meatus is of importance in the formation of nasal polyps(NP) in early stage, which may be the major cause of NP formation in middle meatus. 相似文献