全文获取类型
收费全文 | 50050篇 |
免费 | 5391篇 |
国内免费 | 2605篇 |
专业分类
耳鼻咽喉 | 527篇 |
儿科学 | 759篇 |
妇产科学 | 451篇 |
基础医学 | 2870篇 |
口腔科学 | 864篇 |
临床医学 | 6185篇 |
内科学 | 4397篇 |
皮肤病学 | 491篇 |
神经病学 | 1009篇 |
特种医学 | 1706篇 |
外国民族医学 | 4篇 |
外科学 | 4130篇 |
综合类 | 13687篇 |
现状与发展 | 10篇 |
预防医学 | 5561篇 |
眼科学 | 700篇 |
药学 | 6357篇 |
91篇 | |
中国医学 | 5845篇 |
肿瘤学 | 2402篇 |
出版年
2024年 | 289篇 |
2023年 | 771篇 |
2022年 | 1853篇 |
2021年 | 2306篇 |
2020年 | 1976篇 |
2019年 | 1073篇 |
2018年 | 1103篇 |
2017年 | 1476篇 |
2016年 | 1111篇 |
2015年 | 2189篇 |
2014年 | 2765篇 |
2013年 | 3311篇 |
2012年 | 4680篇 |
2011年 | 4832篇 |
2010年 | 4335篇 |
2009年 | 3781篇 |
2008年 | 3780篇 |
2007年 | 3644篇 |
2006年 | 3122篇 |
2005年 | 2417篇 |
2004年 | 1743篇 |
2003年 | 1447篇 |
2002年 | 1168篇 |
2001年 | 985篇 |
2000年 | 787篇 |
1999年 | 386篇 |
1998年 | 126篇 |
1997年 | 126篇 |
1996年 | 119篇 |
1995年 | 93篇 |
1994年 | 66篇 |
1993年 | 35篇 |
1992年 | 27篇 |
1991年 | 18篇 |
1990年 | 24篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1966年 | 2篇 |
1965年 | 4篇 |
1964年 | 2篇 |
1962年 | 2篇 |
1958年 | 3篇 |
1957年 | 5篇 |
1956年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
嗅觉诱发电位的实验研究 总被引:1,自引:0,他引:1
目的:观察电刺激家兔嗅区黏膜记录的诱发电位的波形及其稳定性,探讨一种可以客观评价嗅觉功能的方法。方法:将双极刺激电极经家兔前鼻孔置于嗅区黏膜,给予电刺激,在颅顶记录嗅觉诱发电位(OEPs);改变刺激参数和部位,观察对电位潜伏期、阈值和波形的影响。结果:在颅顶前方近嗅球处记录到一组波形稳定的N1-P1-N23相复合波。潜伏期为:N1波20.6ms,P1波33.5ms,N2波58.3ms;改变刺激强度对各波无明显影响;改变刺激频率对各波影响较大,频率过高.波形分化较差。结论:正常OEPs是一组波形稳定的负-正-负3相复合波,波形稳定、重复性好,各参量可作为评价嗅觉功能变化的有用指标。 相似文献
32.
黄芪治疗糖尿病肾病近期疗效观察 总被引:1,自引:0,他引:1
目的 观察黄芪注射液治疗Ⅳ期糖尿病肾病的疗效。方法 Ⅳ期糖尿病肾病 58例随机分为两组 ,治疗组在常规治疗基础上加黄芪注射液 30ml/d静滴。对照组不用黄芪注射液 ,余同治疗组 ,共治疗 2个疗程 2 8d。结果 治疗组治疗前后对比尿蛋白减少 (P <0 0 1 ) ,血白蛋白上升 ,LDL、TG、TC下降 (P <0 0 5) ,疗效优于对照组。结论 黄芪注射液治疗Ⅳ期糖尿病肾病有效 相似文献
33.
34.
Facilitating effect of histamine on spatial memory deficits induced by dizocilpine as evaluated by 8-arm radial maze in SD rats 总被引:3,自引:3,他引:3
HUANG Yu-Wen CHEN Zhong~ HU Wei-Wei ZHANG Li-San WU Wei YING Li-Yang WEI Er-Qing Department of Neurobiology Pharmacology School of Medicine Zhejiang University Hangzhou China 《Acta pharmacologica Sinica》2003,(12)
AIM: To investigate whether or not histamine is involved in spatial memory deficits induced by dizocilpine (MK-801) as evaluated by 8-arm radial maze of rats. METHODS: 8-Arm (4-arm baited) radial maze was used to measure spatial memory in rats. RESULTS: Bilaterally intrahippocampal (ih) injection of MK-801 (0.3 μg/site) impaired working memory and reference memory in rats. Both histamine (50, 100 ng/site, ih) and intraperitoneal (ip) injection of histidine (100, 200 mg/kg) markedly improved the spatial memory deficits induced by MK-801. On the other hand, the ameliorating effect of histidine (100 mg/kg, ip) was completely antagonized by α-fluoromethylhistidine (α-FMH, 5 μg/site, ih), a potent and selective histidine decarboxylase (HDC) inhibitor, and H_1-antagonist pyrilamine (1 μg/site, ih), but not by H_2-antagonist cimetidine, even at a high dose (2.5 μg/site, ih). CONCLUSION: The hippocampal histamine plays an important role in the ameliorating effect on MK-801-induced spatial memory deficits, 相似文献
35.
目的 为了开发我国珍稀动物——吉林双阳梅花鹿的基因资源,在分子水平上揭示鹿药材的药理作用。方法 构建了梅花鹿脾脏细胞cDNA质粒文库,克隆了一些看家基因并进行了序列分析。结果 其中的一个序列在核酸及推导的氨基酸序列水平上与编码人、犬、大鼠、小鼠核蛋白体蛋白L27(ribosomal protein L27)cDNA序列和对应的氨基酸序列高度同源,并具有完整的开放阅读框架(ORF)。结论 发现了双阳梅花鹿核蛋白体蛋白L27全长cDNA序列,此序列已经在(Genbank中登录,登录号为:AF373231。 相似文献
36.
高效液相-荧光检测法测定兔血浆羟基喜树碱方法的研究 总被引:1,自引:0,他引:1
目的 :为了测定羟基喜树碱在人体内的血药浓度 ,建立高效液相 -荧光检测法以测定兔血浆中羟基喜树碱的含量。方法 :色谱柱为DiscoveryC18(15cm× 4 6cm ,5 μm) ,流动相为柠檬酸缓冲液 -乙腈 - 75nmol·L-1磷酸二氢钾 (70∶2 3∶7) ,75nmol·L-1磷酸二氢钾中含 1%三乙胺。流速为 1 0mL·min-1,柱温为 4 0℃ ,荧光检测波长为λex36 3nm和λem5 30nm。结果 :该方法的线性范围为 13 76 5 6~ 195 7 4 4 6 8ng·mL-1(r =0 9993) ;提取回收率和方法回收率分别为 80 90 %~ 10 3 5 9% ,10 2 72 %~ 10 8 16 % ;日内RSD≤ 7 4 9% ,日间RSD≤ 9 4 0 %。最低检测限为 5 2ng·mL-1。结论 :主效渡相—荧光法专属性强 ,重现性好 ,操作简便 ,可用于羟基喜树碱的药代动力学研究和血药浓度监测。 相似文献
37.
Circulating and luminal testicular factors affect LRP-2 and Apo J expression in the epididymis following efferent duct ligation 总被引:4,自引:0,他引:4
Apolipoprotein J (clusterin or sulfated glycoprotein-2) has been shown to be secreted by the epididymal principal cells, whereupon it binds to sperm in the lumen. Apolipoprotein J also is endocytosed by principal cells along the epididymis. Recently, it has been demonstrated that low-density lipoprotein receptor-related protein-2 (LRP-2) mediates the endocytosis of Apo J and is present in the epididymis. The purpose of the present study was to determine the factors regulating the synthesis of these 2 proteins in various experimentally treated animals. The epididymides of adult rats were fixed with Bouin's fluid and examined with anti-Apo J and anti-LRP-2 antibodies by a light microscope immunocytochemical method. In normal adult animals, expression of Apo J was evident in principal cells of all epididymal regions except the proximal initial segment. Diffuse cytoplasmic staining indicated Apo J secretion. Reactive apical vesicles, presumably endosomal in nature, suggested endocytosis of Apo J. Lipoprotein receptor-related protein-2 expression was solely apical in nature and was seen as an intense apical band in principal cells of all regions except the proximal and distal initial segment and distal caput regions of the epididymis. Hypophysectomy, up to 28 days after the procedure, did not affect expression of Apo J or LRP-2 in principal cells along the entire epididymis. Orchidectomy, with or without testosterone replacement at all time intervals examined, also did not affect LRP-2 expression along the entire epididymis. This also was noted for Apo J expression in all regions except the proximal initial segment. Thus, expression of these 2 proteins does not appear to be regulated by testicular or pituitary factors. In contrast, bilateral as well as unilateral (intact and ligated sides) efferent duct ligation resulted in dramatic differences in LRP-2 and Apo J expression in principal cells in the various epididymal regions. In the case of LRP-2, a complete absence of reaction was noted in principal cells along the entire epididymis. As for Apo J, expression in the distal initial segment, intermediate zone, and caput region remained unchanged compared with that in normal adult animals, whereas in the corpus and cauda epididymides, results of cytoplasmic staining were negligible. These results suggest that under conditions of efferent duct ligation, a circulating factor emanates from the testis to inhibit expression of LRP-2 and Apo J in these epididymal regions. Furthermore, because Apo J was affected in a region-specific manner, unlike the case for LRP-2, different factors appear to be involved for each protein. These factors may be produced to inhibit proteins from being synthesized by the epididymis in the absence of luminal testicular input and may exist in cases of congenital and pathologic epididymal tubule blockages as well as after vasectomy. In the case of immunostaining for Apo J in the proximal initial segment only, normally unreactive principal cells in control adult animals became intensely reactive after orchidectomy as well as bilateral and unilateral (ligated side only) ligation. As this was not the case for hypophysectomized animals and the intact side of unilateral efferent duct-ligated animals, it is suggested that a testicular factor entering via the lumen of the efferent ducts serves to inhibit Apo J expression in this area. The present data also reveal that after efferent duct ligation, there are circulating factors that inhibit Apo J expression in a region-specific manner (corpus and cauda) and that inhibit LRP-2 expression along the entire epididymis and that these are derived from the testis. Furthermore, the data reveal that a testicular luminal factor appears to inhibit Apo J expression in the proximal initial segment of normal adult animals. Key words: Principal cells, orchidectomy, glycoprotein 330, clusterin, sulfated glycoprotein-2. 相似文献
38.
与人类免疫缺陷病毒相关性耳鼻咽喉部卡波济肉瘤21例报告 总被引:1,自引:0,他引:1
报告21例与人类免疫缺陷病毒(HIV)相关性耳鼻咽喉部卡波济肉瘤,其主要局部表现是鼻出血、鼻塞、咽喉干燥、异物感及结节状新生物,并对HIV感染与卡波济肉瘤的关系、病例特点及诊断依据进行讨论。 相似文献
39.
新生儿败血症单个核细胞产生肿瘤坏死因子α的能力及意义 总被引:1,自引:0,他引:1
探讨新生儿败血症患儿单个核细胞产生肿瘤坏死因子α(TNFα)的能力及意义。方法用ELISA法检测TNFα,用内毒素(LPS)体外诱导单个核细胞产生TNFα检测单个核细胞产生TNFα的能力。结果新生儿败血症患儿病程<4d者血浆中可测到TNFα,而>4d者及健康对照者未能测到。单个核细胞产生TNFα的能力,病程<4d者与>4d者无差异,二者均低于健康对照。存活儿及死亡儿出院或临终前血浆TNFα均测不到,而单个核细胞产生TNFα的能力,死亡者低于存活者及健康对照,后二者无差异。结论TNFα可能仅在败血症早期起作用。起病后败血症患儿继续产生TNFα的能力将降低,且单个核细胞产生TNFα的能力与病情变化一致。对判断新生儿败血症患儿的预后有重要价值。 相似文献
40.
NK细胞识别的新模式——压力诱导模式 总被引:3,自引:0,他引:3
T、B细胞通过TCR和BCR介导抗原识别模式,巨噬细胞通过模式识别受体(pattern recognition receptor,PRR)介导病原体相关的分子模式(pathogen associated molecular pattern, PAMP)或凋亡细胞相关的分子模式(apoptotic cell associated molecular pattern, ACAMP),比TCR,BCR和PRR更为复杂的是NK细胞的受体,迄今为止,已发现有数十种之多,分属抑制性受体和活化性受体两大类.各大类又包括数个家族,体现了NK细胞受体的多样性,介导了NK细胞的不同识别模式,分别传递不同的活化信号和抑制信号[1-2]. 相似文献