全文获取类型
收费全文 | 756篇 |
免费 | 49篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 22篇 |
妇产科学 | 11篇 |
基础医学 | 61篇 |
口腔科学 | 24篇 |
临床医学 | 65篇 |
内科学 | 127篇 |
皮肤病学 | 8篇 |
神经病学 | 53篇 |
特种医学 | 30篇 |
外科学 | 186篇 |
综合类 | 51篇 |
预防医学 | 84篇 |
眼科学 | 7篇 |
药学 | 54篇 |
中国医学 | 1篇 |
肿瘤学 | 20篇 |
出版年
2021年 | 8篇 |
2020年 | 8篇 |
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 6篇 |
2016年 | 9篇 |
2015年 | 15篇 |
2014年 | 13篇 |
2013年 | 36篇 |
2012年 | 28篇 |
2011年 | 26篇 |
2010年 | 21篇 |
2009年 | 33篇 |
2008年 | 36篇 |
2007年 | 31篇 |
2006年 | 35篇 |
2005年 | 18篇 |
2004年 | 31篇 |
2003年 | 30篇 |
2002年 | 32篇 |
2001年 | 24篇 |
2000年 | 21篇 |
1999年 | 16篇 |
1998年 | 16篇 |
1997年 | 13篇 |
1996年 | 12篇 |
1994年 | 10篇 |
1993年 | 16篇 |
1992年 | 26篇 |
1991年 | 12篇 |
1990年 | 8篇 |
1989年 | 11篇 |
1988年 | 13篇 |
1987年 | 11篇 |
1986年 | 14篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 12篇 |
1977年 | 7篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1972年 | 7篇 |
1971年 | 7篇 |
1970年 | 7篇 |
1969年 | 6篇 |
1968年 | 8篇 |
1965年 | 4篇 |
排序方式: 共有807条查询结果,搜索用时 593 毫秒
21.
22.
23.
Modulation of in vitro eosinophil progenitors by hydrocortisone: role of accessory cells and interleukins 总被引:1,自引:0,他引:1
The growth of human eosinophil progenitors (CFU-Eo) and the modulation of growth by hydrocortisone were studied as functions of the presence of lymphocytes and monocytes in marrow cells under study; and the source of colony-stimulating factors, specifically, media conditioned by macrophage-like cell line, GCT; phytohemagglutinin-stimulated mononuclear cells (PHA-LCM); or the T cell line, MO. CFU-Eo growth was greatest in marrow containing accessory cells as compared to marrow depleted of accessory cells; and in marrow treated with phytohemagglutinin-stimulated leukocyte conditioned media (PHA-LCM) or MO (T cell line)-conditioned medium (MO-CM) as compared with GCT cell- conditioned medium (GCT-CM). Hydrocortisone reproducibly inhibited eosinophil progenitor growth in unfractionated marrow stimulated by GCT- CM. This effect was abrogated by admixing irradiated mononuclear cells or T lymphocytes with the target marrow or by adding interleukin 1 or interleukin 2 (IL-1, IL-2). Inhibition by hydrocortisone did not occur when monocyte and T lymphocyte depleted marrow was studied. Unlike GCT- CM, MO-CM and PHA-LCM stimulated equal proportions of eosinophil progenitors in nondepleted and accessory cell-depleted marrow and demonstrated less hydrocortisone inhibition. However, both GCT-CM and PHA-LCM produced in the presence of hydrocortisone stimulated significantly fewer CFU-Eos in both unfractionated and accessory cell- depleted marrow target populations. These results indicate that the growth of CFU-Eo and inhibition of growth by hydrocortisone is a direct function of a monocyte-T cell interaction and probably is mediated through effects on the production/release of eosinophil colony stimulating factor (Eo-CSF). 相似文献
24.
Interactions between vascular endothelial cells and blood platelets have been investigated using a model microcirculation consisting of microcarrier beads colonized with human umbilical vein endothelial cells (HUVECs) and perfused with washed platelet suspensions. To simulate the effects of endothelial desquamation and exposure of subendothelium, fibrillar collagen in suspension was coinjected with the platelets. In this model, neither the passage of platelets alone nor collagen alone stimulated prostacyclin (PGI2) production by the HUVECs. Platelets activated by coinjection with collagen released thromboxane A2 (TXA2), and this was associated with the simultaneous production of PGI2 by the HUVECs. By means of double-isotope experiments with [3H]arachidonic acid (AA) incorporated into platelets and [14C]-AA into HUVECs, it was shown that all the PGI2 generated was derived from platelet AA and/or endoperoxides. This interpretation was strengthened by the finding that PGI2 production was not prevented by treatment of HUVECs with indomethacin followed by perfusion with collagen-stimulated platelets. AA metabolites in double-isotope label experiments were further characterized by reverse-phase chromatography, and it was shown that both cyclooxygenase and lipoxygenase products of the HUVECs were derived from platelet membrane lipid. Thrombin regularly produced transient PGI2 release, but showed rapid tachyphylaxis. Platelet-derived compounds including ADP, ATP, and platelet-activating factor (PAF) did not produce PGI2 release by HUVECs in this system. Thus, the transfer of AA and metabolites from collagen- stimulated platelets is likely to be the mechanism for PGI2 production in the context of minor degrees of endothelial desquamation. 相似文献
25.
Leisha Diane Nolen Lynda Osadebe Jacques Katomba Jacques Likofata Daniel Mukadi Benjamin Monroe Jeffrey Doty Lem's Kalemba Jean Malekani Joelle Kabamba Pierre Lokwa Bomponda Jules Inonga Lokota Marcel Pie Balilo Toutou Likafi Robert Shongo Lushima Jean-Jacques Muyembe Tamfum Emile Wemakoy Okitolonda Andrea M. McCollum Mary G. Reynolds 《The American journal of tropical medicine and hygiene》2015,93(2):410-415
An increased incidence of monkeypox (MPX) infections in the Democratic Republic of the Congo was noted by the regional surveillance system in October 2013. Little information exists regarding how MPX is introduced into the community and the factors associated with transmission within the household. Sixty-eight wild animals were collected and tested for Orthopoxvirus. Two of three rope squirrels (Funisciurus sp.) were positive for antibodies to Orthopoxviruses; however, no increased risk was associated with the consumption or preparation of rope squirrels. A retrospective cohort investigation and a case–control investigation were performed to identify risk factors affecting the introduction of monkeypox virus (MPXV) into the community and transmission within the home. School-age males were the individuals most frequently identified as the first person infected in the household and were the group most frequently affected overall. Risk factors of acquiring MPXV in a household included sleeping in the same room or bed, or using the same plate or cup as the primary case. There was no significant risk associated with eating or processing of wild animals. Activities associated with an increased risk of MPXV transmission all have potential for virus exposure to the mucosa. 相似文献
26.
Cox CD McCollum JM Allen MS Dar RD Simpson ML 《Proceedings of the National Academy of Sciences of the United States of America》2008,105(31):10809-10814
Stochastic fluctuations (or “noise”) in the single-cell populations of molecular species are shaped by the structure and biokinetic rates of the underlying gene circuit. The structure of the noise is summarized by its autocorrelation function. In this article, we introduce the noise regulatory vector as a generalized framework for making inferences concerning the structure and biokinetic rates of a gene circuit from its noise autocorrelation function. Although most previous studies have focused primarily on the magnitude component of the noise (given by the zero-lag autocorrelation function), our approach also considers the correlation component, which encodes additional information concerning the circuit. Theoretical analyses and simulations of various gene circuits show that the noise regulatory vector is characteristic of the composition of the circuit. Although a particular noise regulatory vector does not map uniquely to a single underlying circuit, it does suggest possible candidate circuits, while excluding others, thereby demonstrating the probative value of noise in gene circuit analysis. 相似文献
27.
目的研究呼吸纯氧对健康人听感觉门控P50的影响。方法右利手、健康男性大学生志愿者28名,根据随机数字表分为对照组(n=12)和实验组(n=16)。佩戴面罩,对照组呼吸空气,实验组呼吸医用纯氧60 min。应用条件-测试刺激,记录吸氧前(pre0)、吸氧20 min(Oxy20)、吸氧50 min(Oxy50)、吸氧后30 min(post30)的脑电图,计算听觉P50潜伏期和P50感觉门控电位(S1与S2振幅之差)。结果 S1刺激在4个时间点各组P50潜伏期相对稳定(P0.7);吸氧50 min时,实验组比对照组P50潜伏期缩短(P0.05)。S2刺激在4个时间点各组P50潜伏期相对稳定(P0.30),两组间比较无显著性差异(P0.05)。对照组P50门控电位比较稳定(P=0.70),而实验组随吸氧时间逐渐延长,电位越来越高,停止吸氧后,电位迅速回落,Oxy20和post30(P=0.04)、Oxy50和post30(P=0.02)相比均有显著性差异。组间比较,4个时间点均无显著性差异(P0.05)。结论健康人吸60 min纯氧,可能缩短对刺激的反应时间,有增强听觉门控电位的趋势。 相似文献
28.
Emmanuel T Idowu Henry CN Ajaegbu Ahmed I Omotayo Oluwagbemiga O Aina Olubunmi A Otubanjo 《African health sciences》2015,15(4):1262-1270
Background
Lime extracts of powdered combination of seeds of Picralima nitida, stem bark of Alstonia boonei and leaves of Gongronema latifolium is a common remedy used in the treatment of malaria in South Western Nigeria.Objective
To determine the antiplasmodial activities of the combined herbal extracts and its impact on the haematological, hepatological and renological parameters in mice.Methods
The 4-day suppressive and curative tests were used to assess the antiplasmodial activities of the extract in mice infected with chloroquine-sensitive Plasmodium berghei at concentration of 200mg/kg, 400mg/kg and 800mg/kg body weight. The haematological parameters including red blood cells, white blood cells, packed cell volume and haemoglobin count were analysed with an auto analyser. The activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were determined, while urea, protein and creatinine were analysed by standard procedural methods.Results
The 4-day suppressive test revealed that the test extract achieved percentage suppression of 39.0%, 41.6% and 54.68% for the 200mg/kg, 400mg/kg and 800mg/kg concentration respectively. Additionally, the curative test achieved a high percentage suppression of 80.97%, 83.84% and 86.16% at the 200mg/kg, 400mg/kg and 800mg/kg concentration respectively. The extracts did not induce significant change on haematological parameters (P>0.05), while significant elevation in the values of the ALT and AST (P<0.05) was observed and elevation of creatinine (P<0.05) at 800mg/kg.Conclusions
The results support the traditional use of the herbal combination in the treatment of malaria, however the liver cells were impacted by the extracts in bioassay conducted with mice. 相似文献29.
30.
DC Bosanquet CN Jones N Gill P Jarvis MH Lewis 《Annals of the Royal College of Surgeons of England》2013,95(1):15-19