全文获取类型
收费全文 | 73859篇 |
免费 | 7905篇 |
国内免费 | 4133篇 |
专业分类
耳鼻咽喉 | 471篇 |
儿科学 | 4813篇 |
妇产科学 | 454篇 |
基础医学 | 5471篇 |
口腔科学 | 534篇 |
临床医学 | 6792篇 |
内科学 | 19050篇 |
皮肤病学 | 542篇 |
神经病学 | 1269篇 |
特种医学 | 3269篇 |
外国民族医学 | 20篇 |
外科学 | 10264篇 |
综合类 | 11669篇 |
现状与发展 | 23篇 |
一般理论 | 3篇 |
预防医学 | 2910篇 |
眼科学 | 441篇 |
药学 | 6593篇 |
64篇 | |
中国医学 | 4589篇 |
肿瘤学 | 6656篇 |
出版年
2024年 | 287篇 |
2023年 | 1775篇 |
2022年 | 2567篇 |
2021年 | 3335篇 |
2020年 | 3509篇 |
2019年 | 3067篇 |
2018年 | 2902篇 |
2017年 | 3172篇 |
2016年 | 3628篇 |
2015年 | 3271篇 |
2014年 | 5039篇 |
2013年 | 5194篇 |
2012年 | 4246篇 |
2011年 | 4533篇 |
2010年 | 3570篇 |
2009年 | 3451篇 |
2008年 | 3506篇 |
2007年 | 3512篇 |
2006年 | 3370篇 |
2005年 | 2815篇 |
2004年 | 2169篇 |
2003年 | 1887篇 |
2002年 | 1656篇 |
2001年 | 1533篇 |
2000年 | 1288篇 |
1999年 | 1066篇 |
1998年 | 1070篇 |
1997年 | 934篇 |
1996年 | 866篇 |
1995年 | 740篇 |
1994年 | 735篇 |
1993年 | 567篇 |
1992年 | 552篇 |
1991年 | 492篇 |
1990年 | 428篇 |
1989年 | 360篇 |
1988年 | 339篇 |
1987年 | 269篇 |
1986年 | 254篇 |
1985年 | 300篇 |
1984年 | 269篇 |
1983年 | 164篇 |
1982年 | 206篇 |
1981年 | 195篇 |
1980年 | 170篇 |
1979年 | 146篇 |
1978年 | 122篇 |
1977年 | 107篇 |
1976年 | 113篇 |
1975年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
Summary Techniques are described for the rapid isolation, monolayer culture, and phenotypical characterization of embryonic Day 12 (E12) rat liver epithelial cells. In vitro assays of the differentiation potential of these cells are currently being performed under conditions that make use of-modified Eagle's medium supplemented with fetal bovine serum, insulin, and dexamethasone with or without sodium butyrate. In the absence of sodium butyrate, the cells differentiate along the hepatocytic cell lineage, whereas in its presence they express the phenotype of the biliary ductal epithelial cell lineage. 相似文献
152.
A Contextual Family/Systems Approach to Pediatric Psychology: Introduction to the Special Issue 总被引:2,自引:5,他引:2
Introduced the special issue on "Family System in PediatricPsychology" by organizing the papers around a series of themesrelevant to understanding families in pediatric psychology.Themes reflect the relationships between parent and child adjustment,family subsystems, legacies and traditions, social support systems,family interventions, the constancy of change in families, thechallenges of conducting longitudinal research, the inclusionof fathers, and the importance of a competency framework inpediatric family psychology. The paper concludes with recommendationsfor pediatric family psychology, including suggestions for increasingdiversity, expanding methodological approaches, and enhancingfamily competence. 相似文献
153.
NF-κB在人肝细胞肝癌中的表达及与HBV X蛋白的关系 总被引:2,自引:0,他引:2
目的:研究核转录因子NF--κB在人肝细胞肝癌组织中的表达及其与乙型肝炎病毒(HBV )X蛋白的关系。方法;用免疫组织化学S-P法,检测52例人肝细胞肝癌组织中核转录因子NF--κB及HBV X蛋白的表达;用脂质体介导的基因转染法将HBV x基因真核表达载体pcDNA3.1-HBX转染入人肝癌细胞系HCC-9204,检测肝癌细胞内核转录因子NF--κB的表达。结果:52例人肝细胞肝癌组织均有核转录因子NF--κB的广泛表达,并且在11例HBV X蛋白阳性的肝癌组织,核转录因子NF--κB位于细胞胞质和胞核,而在41例HBV X蛋白阴性的肝癌组织,核转录因子NF--κB位于肝癌细胞的胞质。将HBV x基因真核表达载体pcDNA3.1-HBX转染 入人肝癌细胞系HCC-9204,并在稳定表达X蛋白 的肝癌细胞,核转录因子NF--κB定位于其胞质和胞核,而未进行基因转染的亲体细胞,核转录因子NF--κB仅定位于细胞质,细胞核无核转录因子NF--κB的表达。结论:核转录因子NF--κB在人肝细胞肝癌组织中广泛表达,人肝细胞肝癌中存在着核转录因子NF--κB的异常激活,并且核转录因子NF--κB的异常激活与HBV X蛋白有关,X蛋白激活核转录因子NF--κB, 使其从细胞转位于细胞核,这可能在HBV相关的人原发性肝癌肝癌的发生中起一定作用。 相似文献
154.
155.
Behavioral Upset in Medical Patients-Revised: Evaluation of a Parent Report Measure of Distress for Pediatric Populations 总被引:1,自引:0,他引:1
Examined the utility of a new parent-report measure designedspecifically for pediatric inpatients, the Behavioral Upsetin Medical Patients-Revised (BUMP-R). The BUMP-R was administeredto 151 mothers of hospitalized children ages 412 yearsthe day following the child's hospital admission. The BUMP-Rdemonstrated good internal consistency and a factor analysisrevealed four factors identified as negativity/agitation, amiability,dysphoria, and noncom-pliance. Children exhibiting behavioraldistress at home were more likely to experience adjustment problemsupon hospitalization. Demographic and illness-related variableswere not substantial risk factors for hospital adjustment difficulties. 相似文献
156.
Laura Cerni Giancarlo Biancotto Adriana Tondolo Paolo Bogoni 《Food and Agricultural Immunology》1998,10(4):307-315
A fast and simple extraction procedure was developed for simultaneous determination in bovine liver of two veterinary drugs, widely used as growth promoters in meat production: dexamethasone (a synthetic corticosteroid drug) and clenbuterol (a beta2‐adrenergic agonist drug). Liver samples were extracted by acetonitrile, without any clean‐up step. Two different ELISAs, specific for the two classes of drugs, were used to determine the residue concentration in the extracts. The intra‐ and inter‐extraction variability was determined at different concentrations: the intra‐extraction coefficients of variation (CVs) were between 2.5 and 17.7% for dexamethasone and between 0.9 and 9.8% for clenbuterol; the inter‐extraction CVs were between 2.0 and 16.8% for dexamethasone and between 0.5 and 10.8% for clenbuterol. Recovery ranged from 92 to 154% for dexamethasone and from 78 to 105% for clenbuterol. The limit of detection was 1.43 ng g?1 and 0.43 ng g?1, respectively. The limit of quantification for dexamethasone was 2.09 ng g?1 and for clenbuterol was 0.72 ng g?1. The combination of the new extraction procedure with an ELISA detection permitted the rapid semi‐quantitative determination of both dexamethasone at its maximum residue level (MRL: 2.5 ng g?1 in liver tissue), and clenbuterol at low concentration level. 相似文献
157.
I. A. Vinogradova A. V. Bukalev M. A. Zabezhinski A. V. Semenchenko V. Kh. Khavinson V. N. Anisimov 《Bulletin of experimental biology and medicine》2008,145(4):472-477
Exposure of male rats to permanent or natural illumination of North-Western Russia accelerated their death in comparison with
animals exposed to standard (12 h) light. Permanent illumination promoted the development of spontaneous tumors in comparison
with the standard photoregimen. Injection of epithalone (synthetic Ala-Glu-Asp-Gly peptide; subcutaneously 0.1 μg/rat 5 times
a week from the age of 4 months until natural death) virtually did not change the mean lifespan of male rats, but was associated
with a significant (p<0.05) normalization of population aging rate and hence, time of mortality rate doubling in groups exposed to natural or constant
illumination. Epithalone injected to rats exposed to any photoregimen significantly inhibited the development of spontaneous
tumors, primarily testicular leydigomas and leukemias.
__________
Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 145, No. 4, pp. 455–460, April, 2008 相似文献
158.
Under the condition of obvious iron-overload, there is a zonal hernoeiderin (iron) deposition in hepatic lobules. The deposition is heavtest in the periporfal (zone 1) and lightest in the perivenws (zone 3) hepatocytes. However, the mechanism for this pattern of iron deposition is obscure. Hepatic tissues from control, iron-deficlent or ironoverloaded Wistar rats me used to study its pathogenesis. iron-deficiency was Induced by a low Iron regimen. Ironoverload was produced by repeated intraperitoneal injections of ferric nitrilotriace-We (Fe3+ -NTA) for 1–4 months. Liver tissues of the rats were lmmunohistochemically and histochemically stained for tmnaferrin receptor (TfR), transferrin (Tf), ferritin (Ft), and iron. The staining intensity of TfR, Tf and Ft increased in hepatocytes of iron-deflctent rats and decreased in that of the iromverloaded in comparison with the control rats. TfR atalning was strong in zone 1, with gradual transition into weak staining in zone 3 hepatocytes of the rat liver. TfR located primarily on the hepatocyte membrane. Tf had both membranous and cytoplasmic distribution. Many hepatocytes in group B had strong cytoplasmic Tf staining. Conversely, only a few hepatocytes had weakly stained cytoplasmic Tf in group C. Hepatocytes and Kupffer cells were Ft positive in control rats. Ft was distributed only in the cytoplasm. The staining intensity of Ft was stronger in zone 3 than in zone 1 hepatocytes of iron-deficient rats. In iron-overloaded rats, the iron deposition was severe in zone 1 and mild in zone 3 hepatocytes. These findings suggest that uptake of iron into hepatocytes in vivo is regulated and mediated by TfR and Tf. Gradient TfR distribution from zone 1 to 3 hepatocytes and active TfR-Tf mediated iron uptake resuited in the zonal iron deposition in the hepatic lobule of iron-overloaded rats. 相似文献
159.
160.
肝毒清颗粒对大鼠实验性肝纤维化的防治作用 总被引:3,自引:0,他引:3
目的 :观察肝毒清颗粒的抗纤维化作用。方法 :将Wistar雄性大鼠随机分成 6组 ,即正常对照组、模型组、肝毒清大、中、小剂量组和乙肝宁阳性组 ,采用四氯化碳诱导肝纤维化模型。于造模第 2个月始给予治疗药物。实验持续 3月后将大鼠处死取血作肝功检查及取肝组织做病理检查。结果 :肝毒清能降低AST ,升高TP、ALB ,与模型组比较 (P <0 .0 5 ) ;减轻肝脂肪变性、减少纤维组织增生、促进肝细胞再生。结论 :肝毒清对大鼠肝纤维化有明显防治作用 相似文献