全文获取类型
收费全文 | 306篇 |
免费 | 28篇 |
国内免费 | 13篇 |
专业分类
儿科学 | 13篇 |
妇产科学 | 2篇 |
基础医学 | 33篇 |
口腔科学 | 5篇 |
临床医学 | 74篇 |
内科学 | 67篇 |
皮肤病学 | 2篇 |
神经病学 | 9篇 |
特种医学 | 81篇 |
外科学 | 12篇 |
综合类 | 2篇 |
预防医学 | 12篇 |
眼科学 | 2篇 |
药学 | 17篇 |
中国医学 | 1篇 |
肿瘤学 | 15篇 |
出版年
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2017年 | 7篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 9篇 |
2012年 | 5篇 |
2011年 | 11篇 |
2010年 | 8篇 |
2009年 | 4篇 |
2008年 | 4篇 |
2007年 | 13篇 |
2006年 | 6篇 |
2005年 | 11篇 |
2004年 | 1篇 |
2003年 | 3篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 10篇 |
1998年 | 22篇 |
1997年 | 20篇 |
1996年 | 17篇 |
1995年 | 14篇 |
1994年 | 11篇 |
1993年 | 10篇 |
1991年 | 1篇 |
1990年 | 5篇 |
1989年 | 15篇 |
1988年 | 21篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 13篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 8篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1973年 | 1篇 |
1909年 | 1篇 |
排序方式: 共有347条查询结果,搜索用时 15 毫秒
21.
22.
HT Lam ; SO Schweitzer ; L Petz ; MH Kanter ; DA Bernstein ; S Brauer ; DV Pascual ; BA Myhre ; IA Shulman ; GW Sun 《Transfusion》1997,37(6):577-584
BACKGROUND: The purpose of this study was to search for a more effective transfusion-monitoring system than the existing system of retrospective peer review. STUDY DESIGN AND METHODS: This research used a study-control, preintervention and postintervention design, to evaluate the effectiveness of a prospective physician self-audit transfusion-monitoring system that functioned without the direct involvement of transfusion service physicians. This research also evaluated the effectiveness of issuing to physicians a memo with transfusion guidelines. Three process indicators were used to assess physician behavior at various stages of the blood-ordering process: 1) the number of crossmatches ordered per admission, 2) the transfusion-to- crossmatch ratio, and 3) the number of blood units returned to the laboratory after physician self-auditing. The study used two outcome indicators to reflect overall blood utilization: 1) the percentage of patients who received red cell transfusions and 2) the number of blood units transfused per recipient each month. RESULTS: The prospective physician self-audit system implemented at the study hospital did not reverse physician transfusion decisions, and the process of issuing to physicians a memo with transfusion guidelines at the control hospital failed to reduce blood usage. However, a transient reduction in blood utilization was observed at the study hospital. CONCLUSION: The reduction was hypothesized to be due to a Hawthorne effect, in which observed behavior is affected by the subject's awareness of the research study. 相似文献
23.
目的:建立恢复种植体周围骨缺损的自体骨碎末骨移植材料的实验模型。方法:实验于2005-08/2006-04在大连医科大学动物实验基地(辽宁省重点实验室)完成。①实验材料:健康杂交家犬5只,体质量15~20kg。Bio-Oss骨移植材料为引导骨/组织再生多孔骨无机材料,白色颗粒状,颗粒大小1.0~2.0mm。②实验方法:拔除家犬下颌第1,2,3前臼齿,3个月后行种植术。预备种植体窝,每只犬左右两侧各预备4个,共40个。在每个种植窝内,各植入种植体钛钉1枚,共40枚。用种植转孔时收集的自体骨碎末、Bio-Oss骨移植材料及两者1∶1混合骨碎末恢复种植体颊侧单壁人为骨缺损,以未植骨作空白对照。③实验评估:第9周时观察各组骨量的恢复情况、X线片观察牙槽骨高度、骨小梁致密度及骨整合情况,亚甲基蓝-碱性品红法观察组织学变化。结果:5只家犬钛钉均无脱落,均纳入结果分析。①一般情况:9周时,创口愈合均良好,钛钉稳定,总存留率为100%。骨缺损处已有不同程度恢复,与正常骨组织无明显差别。②9周时各组骨缺损量的测量结果:植入自体骨碎末、Bio-Oss骨移植材料、混合骨碎末及空白对照组的平均骨缺损量分别为1.8125、1.6975、1.5025、2.6375mm。植入混合骨碎末的平均骨缺损量最小,说明恢复最佳。③X线观察骨量的恢复情况:40颗钛钉外周均与骨组织紧密接触,愈合良好。不同组间未见明显骨质密度区别。④组织学观察骨量的恢复情况:低倍镜下见所有钛钉均被周围淡红色的致密骨组织紧密包绕,种植体与骨组织间无蓝色的软组织,产生了直接骨结合界面。结论:应用家犬建立自体骨碎末移植材料恢复种植体周围骨缺损的实验模型效果理想。 相似文献
24.
BRUMFITT W; HAMILTON-MILLER JMT; SMITH GW; AL-WALI W 《QJM : monthly journal of the Association of Physicians》1991,81(1):811-820
SUMMARY Eighty-eight women with a history of recurrent urinary tractinfection (at least four attacks in the preceding 12 months)were randomized to take either norfloxacin 200 mg at night (45patients) or macrocrystalline nitrofurantoin 100 mg at night(43 patients) for 12 months. A decrease in the number of symptomaticattacks while taking this prophylaxis was observed in 94 percent of the patients and this improvement was maintained duringthe 6 months following the end of prophylaxis in 69 per cent.The mean interval between symptomatic episodes while takingprophylaxis was 7.2-fold and 6.9-fold greater, respectively,than in the 12 months before starting prophylaxis. There wereonly nine breakthrough infections during 74 patient-years ofprophylaxis, four in patients taking norfloxacin (two enterococci,one Staphylococcus epidermidis, one Escherichia coli), and fivein those taking macrocrystalline nitrofurantoin (four E. coli,one Klebsiella pneumoniae). Adverse events caused four patientstaking norfloxacin (8 per cent) and seven taking macrocrystallinenitrofurantoin (14 per cent) to stop prophylaxis. Norfloxacinhad a marked suppressive effect on the coliform part of thefaecal flora, with no emergence of resistance. Thus, norfloxacinappears to be an excellent alternative agent to macrocrystallinenitrofurantoin for the prevention of recurrent urinary infections. 相似文献
25.
Prenatal identification of potential donors for umbilical cord blood transplantation for Fanconi anemia 总被引:1,自引:0,他引:1
AD Auerbach ; Q Liu ; R Ghosh ; MS Pollack ; GW Douglas ; HE Broxmeyer 《Transfusion》1990,30(8):682-687
Reported here are studies of Fanconi anemia fetal cells that led to the first use of umbilical cord blood for hematopoietic reconstitution in a clinical trial. Prenatal diagnosis and HLA typing were performed in fetuses at risk for Fanconi anemia (FA) to identify, prior to birth, those that were unaffected with the syndrome and were HLA-identical to affected siblings. Umbilical cord blood was harvested at the delivery of these infants; assays of progenitor cells indicated the presence of colony-forming units-granulocyte-macrophage (CFU-GM) in numbers similar to those of bone marrow CFU-GM that are associated with successful engraftment in HLA-matched allogeneic bone marrow transplantation. The possibility that umbilical cord blood from a single individual can be used as an alternative to bone marrow for hematopoietic reconstitution has now been demonstrated by the successful engraftment of two patients with FA. Progenitor cell assays of umbilical cord blood collected at the birth of a child affected with FA, who had been misdiagnosed on the basis of chorionic villus sampling (CVS) studies, indicated a profound deficiency in colony formation, consistent with previously reported abnormalities in the growth of FA cells in vitro. These results suggest that the hematopoietic disorder in FA is related to an underlying problem with cell proliferation. 相似文献
26.
27.
Patient‐ and family‐centred care in the intensive care unit: a challenge in the daily practice of healthcare professionals 下载免费PDF全文
28.
目的:构建神经原相关的细胞粘附分子(NrCAM)和免疫球蛋白Fc片段融合基因的重组质粒并通过Baculovirus载体转染到昆虫细胞。方法:利用RT-PCR方法从神经母细胞瘤细胞系SK-N-SN获得NrCAM的信号肽区和跨膜区片段并直接克隆到pGEMT载体,经多次酶切、连接、转化、筛选获得NrCAM-Fc的重组副合基因,测序后将此基因通过Baculovirus载体转染至昆虫细胞。结果:多种酶切和测序结果表明NrCAM-Fc的序列与原序列符合率达98%以上,NrCAM与Fc连接处序列保证了Fc的读码框架(ORF)。结论:Baculovirus载体转染效率高,检测方法简便易行。 相似文献
29.
Quality adjusted life years (QALYs) are well recognized as a valid measure for outcomes in cost-effectiveness analyses. However, it is difficult to obtain a summary utility score from health status measure such as the SF-36.
OBJECTIVE: To predict a summary utility score (represented by HUI) from the scores on the SF-36.
METHODS: A structural equation framework was applied to data collected from 1992 to 1995 on the Southern California Kaiser Permanente population (n = 5,794). An instrumental variable (IV) method mitigated the endogeneity in estimating the HUI(MarkII). Socioeconomic and disease variables were used as covariates. A split-sample analysis provided cross-validation.
RESULT: This model predicted 33.68% of the observed variance in HUI index scores with an adjusted R2 of 0.3335. Observed HUI index scores were distributed with a mean of 0.7963 and std. deviation of 0.1796. Parameter estimates of most of the SF-36 components (except General Health & Social Functioning) showed statistical significance at α= 0.05 level. People with high chronic disease scores were found to have low SF-36 scores, and parameter estimates of this covariate were also found statistically significant at α= 0.05 level in all structural equations. However, all the socioeconomic variables showed statistical insignificance. Comparison of "Forecasting" and "Estimation" sub-samples showed satisfactory results during cross-validation.
CONCLUSION: Result of this study provides a quantitative link between two important measures of health status. The present model can be used to estimate overall health utility summary scores from previous studies using the SF-36. 相似文献
OBJECTIVE: To predict a summary utility score (represented by HUI) from the scores on the SF-36.
METHODS: A structural equation framework was applied to data collected from 1992 to 1995 on the Southern California Kaiser Permanente population (n = 5,794). An instrumental variable (IV) method mitigated the endogeneity in estimating the HUI(MarkII). Socioeconomic and disease variables were used as covariates. A split-sample analysis provided cross-validation.
RESULT: This model predicted 33.68% of the observed variance in HUI index scores with an adjusted R
CONCLUSION: Result of this study provides a quantitative link between two important measures of health status. The present model can be used to estimate overall health utility summary scores from previous studies using the SF-36. 相似文献
30.
Reversible oxidant-induced increases in albumin transfer across cultured endothelium: alterations in cell shape and calcium homeostasis 总被引:20,自引:0,他引:20
To determine whether reactive oxygen molecules could directly and reversibly increase the transfer of albumin across an endothelial barrier, we measured albumin transfer across monolayers of endothelium cultured on micropore filters before and after exposure to xanthine and xanthine oxidase. Xanthine and xanthine oxidase increased endothelial albumin transfer in a dose-dependent fashion. Parallel phase contrast and fluorescence microscopy demonstrated retraction of adjacent cells from one another and disruption of the actin filaments. The oxidant- induced increases in albumin transfer and changes in cell shape were reversed by removing xanthine oxidase and then incubating the monolayers for 3 1/2 hours in tissue culture media enriched with fetal bovine serum. However, incubation in tissue culture media without serum resulted in progressive injury and cell death. Hence, the brief exposure to oxidants initiated a progressive injury process that was reversed by incubation in serum. Because intracellular and extracellular calcium are important determinants of cell shape, and because some oxidized membrane lipids act as calcium ionophores, we asked whether oxidants altered endothelial calcium homeostasis. Xanthine-xanthine oxidase increased release of 45Ca++ from preloaded cells. The calcium antagonist lanthanum chloride prevented xanthine- xanthine oxidase increases in endothelial albumin transfer and prevented the changes in cell shape; chelation of extracellular calcium inhibited lysis of endothelium by xanthine-xanthine oxidase; and the calcium ionophore A23187 increased endothelial albumin transfer and mimicked the oxidant-induced changes in cell shape. Lanthanum chloride inhibited these effects of A23187. These data suggest that oxygen radicals can reversibly increase endothelial permeability to macromolecules, that this is associated with reversible changes in endothelial cell shape and actin filaments, and that the changes in cell shape are related to oxidant-induced changes in endothelial calcium homeostasis. 相似文献