全文获取类型
收费全文 | 26919篇 |
免费 | 2631篇 |
国内免费 | 1455篇 |
专业分类
耳鼻咽喉 | 288篇 |
儿科学 | 294篇 |
妇产科学 | 297篇 |
基础医学 | 2937篇 |
口腔科学 | 497篇 |
临床医学 | 3667篇 |
内科学 | 3459篇 |
皮肤病学 | 493篇 |
神经病学 | 1333篇 |
特种医学 | 995篇 |
外国民族医学 | 14篇 |
外科学 | 1805篇 |
综合类 | 4891篇 |
现状与发展 | 3篇 |
一般理论 | 2篇 |
预防医学 | 2416篇 |
眼科学 | 739篇 |
药学 | 3142篇 |
53篇 | |
中国医学 | 1734篇 |
肿瘤学 | 1946篇 |
出版年
2024年 | 69篇 |
2023年 | 395篇 |
2022年 | 1402篇 |
2021年 | 1793篇 |
2020年 | 1338篇 |
2019年 | 975篇 |
2018年 | 1047篇 |
2017年 | 1100篇 |
2016年 | 880篇 |
2015年 | 1433篇 |
2014年 | 1798篇 |
2013年 | 1706篇 |
2012年 | 2589篇 |
2011年 | 2698篇 |
2010年 | 1703篇 |
2009年 | 1417篇 |
2008年 | 1610篇 |
2007年 | 1393篇 |
2006年 | 1163篇 |
2005年 | 1021篇 |
2004年 | 652篇 |
2003年 | 493篇 |
2002年 | 341篇 |
2001年 | 298篇 |
2000年 | 284篇 |
1999年 | 269篇 |
1998年 | 148篇 |
1997年 | 167篇 |
1996年 | 105篇 |
1995年 | 111篇 |
1994年 | 101篇 |
1993年 | 55篇 |
1992年 | 86篇 |
1991年 | 74篇 |
1990年 | 47篇 |
1989年 | 40篇 |
1988年 | 44篇 |
1987年 | 31篇 |
1986年 | 16篇 |
1985年 | 27篇 |
1984年 | 7篇 |
1981年 | 7篇 |
1979年 | 7篇 |
1974年 | 4篇 |
1972年 | 5篇 |
1971年 | 5篇 |
1970年 | 4篇 |
1969年 | 4篇 |
1968年 | 4篇 |
1966年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
三七总皂甙对红系祖细胞增殖调控机理的研究 总被引:13,自引:0,他引:13
采用造血祖细胞体外培养和造血生长因子检测等实验血液学技术,研究三七总皂甙对小鼠红系祖细胞调控的生物学机理。结果表明:三七总皂甙对正常或骨髓抑制一贫血模型小鼠的红系祖细胞增殖有明显促进作用。三七总皂甙亦可提高阿糖胞苷所致祖细胞的“自杀”率;经三七总皂甙诱导制备的脾细胞,L细胞培养上清液和红系祖细胞的直殖具有较高刺激活性。 相似文献
92.
乙醇对人绒毛孕酮分泌的影响 总被引:1,自引:0,他引:1
本工作利用灌流技术观察了四种不同浓度的乙醇(0.5%、1%、2.5%、5%)对妊娠早期人工流产新鲜胎盘绒毛分泌孕酮的影响。结果表明,乙醇具有促进孕酮分泌的作用,并存在剂量依赖的关系。提示乙醇可能破坏胎盘激素内分泌的平衡,从而影响胎儿的正常生长与发育。 相似文献
93.
Sun Hee Na Seung-Hyun Jin Soo Yong Kim 《International journal of psychophysiology》2006,62(2):238-242
Sleep deprivation can affect the waking electroencephalogram (EEG) that may reflect functional organization of the brain. We examined the effect of total sleep deprivation (TSD) on functional organization between different cortical areas from the waking EEG. Waking EEG data were recorded from 18 healthy male volunteers with eyes closed after 8-h night's sleep and after 24 h of TSD. The averaged cross mutual information (A-CMI) after 24 h of TSD were compared to before TSD. 24 h of TSD yielded the decreased A-CMIs in the inter-hemispheric C3-F4, C3-F8, and C3-C4 pairs: therefore, the electrodes that contribute to pairs with significant decrease of A-CMI were C3, F4, F8, and C4. The decreased A-CMIs between C3 and right frontal and central brain areas after 24 h of TSD may reflect the changes of cortico-cortical functional organization by homeostatic process during TSD. Our results of the frontal-area-related A-CMI decreases may support that the frontal brain regions are related to the homeostatic deterioration of brain function due to TSD. 相似文献
94.
Na?Wang Qiu-Liang?Wu Yan?Fang Hai-Qiang?Mai Mu-Sheng?Zeng Guo-Ping?Shen Jing-Hui?Hou Yi-Xin?ZengEmail author 《Journal of translational medicine》2005,3(1):26
Nasopharyngeal carcinoma (NPC) is a tumor derived from epithelial cells and Epstein-Barr virus infection has been reported
to be a cause of this disease. Chemokine receptor CXCR4 was found to be involved in HIV infection and was highly expressed
in human malignant breast tumors and the ligand for CXCR4, CXCL12 (SDF-1), exhibited high expression in organs in which breast
cancer metastases are often found. The metastatic pattern of NPC is quite similar to that of malignant breast tumors. In this
study, we investigated the expression of CXCR4 in nasopharyngeal carcinoma (NPC) tissues by immunohistostaining. We found
different staining patterns, which included localization in the nucleus, membrane, cytoplasm or a combination of them. The
staining intensity was also variable among samples. The metastatic rates in patients with high compared to low or absent expression
was 38.6% versus 19.8%, respectively (P = 0.004). High expression of CXCR4 was associated with poor overall survival (OS = 67.05% versus 82.08%, P = 0.0225). These results suggest that CXCR4 may be involved in the progression of NPC and that a high level of CXCR4 expression
could be used as a prognostic factor. 相似文献
95.
Grigor'eva EP Desheva IuA Donina SA Naĭkhin AN Rekstin AR Barantseva IB Zavitkova EA Moskvicheva TM Zhavoronkov VG Rudenko LG 《Voprosy virusologii》2002,47(4):24-27
In Russia for prevention of influenza in children, aged from 3 to 14 years, the children's live influenza vaccine (LIV), based upon A/Leningrad/134/47/57(H2N2) master strain (LIVI) is used. The need for double immunization appears to be one out of the faulties of this preparation. The study was aimed to comparing the safety, immunogenic activity and prevention of influenza by LIV for adults (LIVII) (A/Leningrad/134/17/57(H2N2 master strain) and LIVI in children aged from 7 to 17 years under similar administration schedule. The safety, the preventive efficacy, humoral and secretory immunity were studied. In total 2486 persons, including 539 children, twice inoculated with LIVI, 971 persons once inoculated with LIVII, and 840 treated by placebo were obserbed. From the data of the clinical observations during 7 days after immunization both vaccines appeared to be low reactogenic. The LIVII advantages in induction of the humoral and secretory antibodies in comparison with children's vaccine had been revealed. Both vaccines were highly efficacious, the efficiency of both preparations was more pronounced after serologic correction of the diagnosis. The results obtained permit to recommend the single immunization by the variant of LIV at the base on A/Leningrad/134/17/57/(H2N2) master strain for prevention of influenza in school children. 相似文献
96.
肝尾状叶的外科解剖及其临床应用 总被引:1,自引:0,他引:1
在42例成人肝脏标本上,研究了肝尾状叶的形态,动脉、静脉和肝管的分布特征;尾状叶常有3个突起,即尾状突、乳头突和下腔静脉后突,且变异较大;尾状叶有两个恒定的蒂,其结构排列由浅入深分别是门静脉支、肝动脉支和肝管。尾状叶静脉有2~5支,其中以3支居多,主要汇入下腔静脉肝后段的中、下1/3部的左前壁。中结合解剖学研究总结了施行肝尾状叶肿瘤切除术的方法和经验。 相似文献
97.
98.
促肝细胞生长素诱导人肝癌细胞(BEL-7402)凋亡 总被引:1,自引:0,他引:1
本文从细胞学、DNA凝胶电泳、流式细胞术三方面研究促肝细胞生长素(pHGF)在体外对肝癌细胞增殖活性的影响。结果表明:pHGF对肝癌BEL-7402细胞增殖有抑制作用,并存在剂量和时间相关性。其48h的半数抑制浓度(ID50)为0.37mg/ml±0.04mg/ml。而37℃灭活的pHGF对BEL-7402细胞增殖在15h无抑制作用,在24和48h抑制作用很弱(ID50>1.5mg/ml)。DNA凝胶电泳结果表明,pHGF可诱导BEL7402细胞产生细胞凋亡(Apoptosis)。流式细胞术(FCM)结果显示:pHGF抑制BEL-7402细胞增殖过程是先使细胞停留在G0/G1期,继而诱导细胞产生凋亡。后两项结果均显示pHGF对人肝癌细胞凋亡的诱导里时间和剂量相关性。 相似文献
99.
In this paper, we propose a new approach aimed at handling the temporal Brainstem Auditory Evoked Potentials (BAEPs) non-stationarity. It is pointed out that for some endocochlear pathologies, BAEPs could be randomly delayed from one response to another. This non-stationarity leads to smoothed BAEPs when applying ensemble averaging or any other technique based on BAEPs stationarity. In that case, waves identification is very difficult, sometimes impossible. The problem consists in estimating time delays. Knowing the distribution of delays allows subsequent study of the dynamic of the cochlea and, perhaps, identification of the nature of its pathology. The approach suggested in this paper is based on Simulated Annealing, used to minimize a non-linear criterion involving delays. This technique is advantageously compared to the non-corrected ensemble averaging method, using a set of simulated data based on a realistic model. As an illustration, results based on real signals recorded from two patients are presented and discussed at the end of the paper. 相似文献
100.
川芎嗪对内毒素脂多糖诱导的体外血脑屏障模型通透性增高的保护作用及其机制 总被引:1,自引:0,他引:1
目的:探讨川芎嗪对内毒素脂多糖(LPS)诱导的体外血脑屏障模型通透性增高的保护作用及其调控机制。方法:利用脑微血管内皮细胞与星型胶质细胞共培养建立体外大鼠血脑屏障模型,随机分为正常对照组、川芎嗪对照组、LPS干预组和川芎嗪治疗组。采用γ计数仪检测~(125)I-BSA通透量观察体外血脑屏障模型通透性的改变,Western印迹法检测紧密连接蛋白(zonula occludens-1,ZO-1)表达量的变化。结果:LPS使体外血脑屏障模型对~(125)I-BSA的通透量明显增加,脑微血管内皮细胞ZO-1蛋白表达下降,川芎嗪治疗组能明显拮抗LPS的上述作用。结论:川芎嗪对LPS诱导的体外血脑屏障通透性增高具有保护作用,其机制与它能影响血脑屏障紧密连接蛋白ZO-1表达有关。 相似文献