全文获取类型
收费全文 | 16405篇 |
免费 | 1254篇 |
国内免费 | 927篇 |
专业分类
耳鼻咽喉 | 69篇 |
儿科学 | 101篇 |
妇产科学 | 109篇 |
基础医学 | 3075篇 |
口腔科学 | 195篇 |
临床医学 | 634篇 |
内科学 | 1755篇 |
皮肤病学 | 205篇 |
神经病学 | 1626篇 |
特种医学 | 331篇 |
外国民族医学 | 5篇 |
外科学 | 653篇 |
综合类 | 4256篇 |
现状与发展 | 4篇 |
预防医学 | 681篇 |
眼科学 | 179篇 |
药学 | 2316篇 |
2篇 | |
中国医学 | 1326篇 |
肿瘤学 | 1064篇 |
出版年
2024年 | 117篇 |
2023年 | 130篇 |
2022年 | 238篇 |
2021年 | 282篇 |
2020年 | 334篇 |
2019年 | 286篇 |
2018年 | 263篇 |
2017年 | 442篇 |
2016年 | 441篇 |
2015年 | 524篇 |
2014年 | 769篇 |
2013年 | 1000篇 |
2012年 | 940篇 |
2011年 | 1085篇 |
2010年 | 890篇 |
2009年 | 816篇 |
2008年 | 908篇 |
2007年 | 918篇 |
2006年 | 908篇 |
2005年 | 739篇 |
2004年 | 728篇 |
2003年 | 651篇 |
2002年 | 571篇 |
2001年 | 474篇 |
2000年 | 439篇 |
1999年 | 390篇 |
1998年 | 288篇 |
1997年 | 262篇 |
1996年 | 289篇 |
1995年 | 263篇 |
1994年 | 239篇 |
1993年 | 239篇 |
1992年 | 202篇 |
1991年 | 153篇 |
1990年 | 148篇 |
1989年 | 124篇 |
1988年 | 125篇 |
1987年 | 105篇 |
1986年 | 92篇 |
1985年 | 125篇 |
1984年 | 120篇 |
1983年 | 54篇 |
1982年 | 92篇 |
1981年 | 91篇 |
1980年 | 62篇 |
1979年 | 42篇 |
1978年 | 39篇 |
1977年 | 34篇 |
1976年 | 31篇 |
1970年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
目的研究HBV转基因小鼠肝脏中NKT细胞的功能与表面PD1、CD28表达的关系。方法分离小鼠肝脏、脾脏、胸腺和腹膜淋巴结单个核细胞,利用流式细胞检测技术,分别检测其淋巴细胞中NKT细胞的频率,同时检测肝脏NKT细胞PD1、CD28的表达及IFN-γ、IL-4的分泌功能,比较肝脏、脾脏、胸腺和腹膜淋巴结这几个主要免疫组织淋巴细胞中NKT细胞所占的比例,并分析肝脏NKT细胞PD1、CD28的表达与细胞功能的关系。结果与正常同品系小鼠比较,HBV转基因小鼠肝脏、脾脏、胸腺和腹膜淋巴结NKT细胞数量明显减少(P<0.05),与脾脏、胸腺和腹膜淋巴结相比,肝脏淋巴细胞中含有大量的NKT细胞;与正常同品系小鼠比较,HBV转基因小鼠肝脏NKT细胞PD1的表达明显增多(P<0.05),CD28的表达明显减少(P<0.05),肝脏NKT细胞IFN-γ、IL-4的分泌功能明显降低(P<0.05)。结论肝脏中含有大量的NKT细胞,HBV转基因小鼠肝脏NKT细胞的功能存在明显的缺陷,并提示PD1的增加和CD28的降低可能与NKT细胞功能的下调密切相关。 相似文献
52.
ContextThe effects of Rhodiola rosea L. (Crassulaceae) polysaccharides (RRPs) on haematopoiesis are poorly understood.ObjectiveTo determine the effects of RRPs on haematopoiesis in mice with aplastic anaemia.Materials and methodsAplastic anaemia was induced in Kunming mice by 60Coγ (2.0 Gy) irradiation and cyclophosphamide administration (50 mg/kg/day for 3 consecutive days; intraperitoneal injection). The in vivo effects of RRPs (10, 20, and 40 mg/kg; intraperitoneal injection) on haematopoiesis were analyzed using peripheral blood tests, histopathological examination of haematopoietic tissues, culture of haematopoietic progenitors and bone marrow stromal cells (BMSCs), and Western blotting of Fas and Fas ligand (FasL). The in vitro effects of RRPs on bone-marrow haematopoietic progenitors and BMSCs were also evaluated.ResultsCompared to anaemic controls, high-dose RRPs (40 mg/kg) significantly increased red blood cells (8.21 ± 0.57835 versus 6.13 ± 1.34623 × 1012/L), white blood cells (5.11 ± 1.6141 versus l.54 ± 1.1539 × 109/L), and BMSCs (10.33 ± 1.5542 versus 5.87 ± 3.1567 × 1012/L) in mice with aplastic anaemia (all p < 0.01). High-dose RRPs significantly increased the formation of colony-forming unit-granulocyte macrophage (CFU-GM), burst-forming unit-erythroid (BFU-E), and colony-forming unit-erythroid (CFU-E; p < 0.01). Fas and FasL protein expression in BMSCs decreased after RRPs administration. Especially at the high dose, RRPs (150 μg/mL) significantly promoted in vitro CFUs-E, BFUs-E, and CFUs-GM formation. RRPs (150–300 μg/mL) also promoted BMSC proliferation.Discussion and conclusionsRRPs helped to promote haematopoietic recovery in mice with aplastic anaemia, facilitating haematopoietic tissue recovery. This study indicated some mechanisms of the haematopoietic regulatory effects of RRPs. Our findings provide a laboratory basis for clinical research on RRPs. 相似文献
53.
目的研究CD34 细胞在卵白蛋白(OVA)致敏小鼠、哮喘小鼠中的表达及布地奈德(BUD)吸入对哮喘小鼠CD34 细胞表达的影响。方法将雄性昆明小鼠随机分成致敏组、哮喘组、BUD干预组、正常对照组。用OVA进行致敏和激发,建立哮喘模型。常规检测骨髓、外周血中有核细胞总数,流式细胞仪检测CD34 细胞。结果致敏小鼠骨髓中CD34 细胞比例为(3.99±1.37)%,较正常小鼠[(2.33±1.27)%]明显增加;外周血中CD34 细胞比例为(1.58±0.63)%,与正常小鼠[(1.50±1.04)%]相比,未见明显变化。哮喘小鼠骨髓中CD34 细胞比例为(5.64±1.87)%,与致敏小鼠相比进一步升高;外周血中CD34 细胞比例为(2.91±1.27)%,与正常小鼠相比亦有明显增加;布地奈德吸入后,骨髓、外周血中CD34 细胞表达分别为(3.77±1.81)%和(1.76±1.06)%,均有明显下降。结论小鼠在OVA致敏状态下骨髓中CD34 细胞表达明显增强,OVA激发后哮喘状态下其表达进一步增强,同时,外周血中CD34 细胞比例也明显增高。布地奈德可以抑制哮喘小鼠骨髓、外周血中CD34 细胞的增殖表达。 相似文献
54.
Calabrese V Scapagnini G Ravagna A Fariello RG Giuffrida Stella AM Abraham NG 《Journal of neuroscience research》2002,68(1):65-75
It is generally recognized that lipid peroxides play an important role in the pathogenesis of several diseases and that sulfhydryl groups are critically involved in cellular defense against endogenous or exogenous oxidants. Recent evidence indicates that lipid peroxides directly participate in induction of cytoprotective proteins, such as heat shock proteins (Hsps), which play a central role in the cellular mechanisms of stress tolerance. Heme oxygenase (HO) is a stress protein that has been implicated in defense mechanisms against agents that may induce oxidative injury, such as endotoxins, cytokines and heme and its induction represents a common feature in a number of neurodegenerative diseases. In the present report we studied regional distribution of heme oxygenase (HO) activity and protein expression, together with that of Hps70, in brain of C57BL6 mice. Endogenous lipid peroxidation was investigated on the basis of the analysis of ultra weak chemiluminescence, hydro peroxides and lipid soluble fluorescent products, and compared to the regional distribution of thiols, antioxidant enzymes and trace metals. Our results show that levels of HO activity and expression of inducible Hsp70 and the ratio of GSH/GSSG in the different brain regions examined were positively correlated with the content of peroxides. Substantia Nigra was the brain area exhibiting the highest levels of HO-2, constitutive and inducible Hsp70, GSSG, peroxides, iron, and calcium, in contrast with the lowest content in GSH, GSH/GSSG ratio and glutathione reductase activity, compared to the other cerebral regions examined. Among these, cortex showed the lowest levels of HO-2, Hsp70, GSSG and peroxides that were associated with the highest levels of GSH and GSH/GSSG ratio. These data support the hypothesis that the glutathione redox state and basal peroxides can directly participate in the signaling pathways of heat shock protein expression and hence of stress tolerance. 相似文献
55.
Neurotrophins regulate survival, neurite outgrowth, and phenotypic maturation of developing neurons. Brain-derived neurotrophic factor (BDNF) can promote the survival of developing cholinergic forebrain neurons in vitro and reduce their degeneration following injury in adult rats. We investigated the role of endogenous BDNF during postnatal development of these cholinergic neurons by analyzing homozygous BDNF-deficient (−/−) mice and their littermates (+/+, +/−). At P6, the number of choline acetyltransferase- (ChAT) positive neurons in the medial septum was 23% lower in BDNF−/− mice, although their brain and body weight was normal. At P15, control (+/+) littermates had 45% more and 45% larger ChAT-positive neurons and a much denser cholinergic hippocampal innervation than at P6, indicative of maturation of the septohippocampal system. In BDNF−/− mice, the number, size, and ChAT-immunostaining intensity of the cholinergic neurons remained the same between P6 and P15 (few mice survive longer). BDNF−/− mice had about three times more TUNEL-labeled (a marker of apoptosis) cells in the medial septum at P6, consistent with (but not proof of) the possibility that the cholinergic neurons were dying. The cholinergic hippocampal innervation in BDNF−/− mice expanded to a lesser extent than in controls and had reduced levels of acetylcholinesterase staining at P15. The developmental deficits were largely similar in the neostriatum of BDNF−/− mice. These findings suggest that BDNF is critical for postnatal development and maturation of cholinergic forebrain neurons. 相似文献
56.
目的 建立昆明小鼠肝纤维化模型.方法 48只昆明小鼠随机分组.实验组40只,腹腔注射20 mg/kg剂量的刀豆蛋白A(ConA),每周一次,共9次.对照组8只,每周一次腹腔注射PBS.所有小鼠在每次注射后24 h采血测ALT、AST.实验组分别于第6、7、8、9次注射后1周各处死8只小鼠,余8只第9周起停止注射,第13周处死.对照组第9次注射后1周处死.所有小鼠处死后取肝脏计算肝脏指数,并作病理检查.结果 实验组第8次注射后出现典型肝纤维化,停止刺激4周仍然有纤维化表现.结论 反复腹腔注射ConA可以建立昆明小鼠肝纤维化模型. 相似文献
57.
乙酰紫草素注射液对小鼠Lewis肺癌生长抑制的研究 总被引:4,自引:1,他引:3
目的:探讨乙酰紫草素注射液对小鼠Lewis肺癌的生长抑制作用。方法:建立C57BL/6小鼠lewis肺癌模型进行体内抗瘤实验并计算抑瘤率。结果:乙酰紫草素注射液高中低剂量组的抑瘤率分别为55.49%,45.25%和28.09%。结论:乙酰紫草素注射液能明显抑制小鼠Lewis肺癌的生长。 相似文献
58.
月见草花浸液对正常小鼠免疫功能的影响 总被引:1,自引:0,他引:1
目的:探讨月见草花提取物对正常小鼠免疫功能的影响。方法:ICR小鼠随机分组,给药8天后测定月见草花浸液对小鼠胸腺重量的影响。应用巨噬细胞吞噬功能测定和空斑形成试验,检测月见草花浸液对正常小鼠部分免疫功能的影响。结果:月见草花浸液可明显促进小鼠的腹腔巨噬细胞的吞噬能力,提高小鼠的抗体生成细胞数。结论:月见草花浸液对小鼠的免疫功能具有一定的免疫促进作用。 相似文献
59.
60.
小鼠体内泻心汤中黄芩苷药代动力学 总被引:3,自引:1,他引:3
目的:研究泻心汤(大黄、黄连、黄芩)中黄酮类成分在小鼠体内药代动力学规律。方法:小鼠灌胃给予泻心汤4.5、9、18g/kg后,用HPLC方法分析血浆中黄酮类成分、测定血浆中黄芩苷浓度经时变化,浓度-时间数据用DAS药代动力学软件进行分析,计算药动学参数。结果:小鼠灌服泻心汤后血浆中检测到黄芩苷、汉黄芩苷和另一黄酮类成分,其中黄芩苷含量最高。泻心汤灌胃给予4.5、9、18g/kg后,黄芩苷主要药代学参数分别为:T1/2=2.77、5.69、6.20h,AUC0-∞=9.09、23.49、39.57μg·h/mL,CL=12.52、6.962、11.50L·h/kg,Vd=50.11、79.56、102.95L/kg,Cmax1=1.89、3.32、4.79μg/mL(Tp1=0.08h),Cmax2=1.46、2.57、4.16μg/mL(Tp2=3h)。结论:泻心汤中黄酮类成分可以吸收进入体内,其中以黄芩苷为主。 相似文献