全文获取类型
收费全文 | 586篇 |
免费 | 15篇 |
国内免费 | 15篇 |
专业分类
耳鼻咽喉 | 6篇 |
儿科学 | 40篇 |
妇产科学 | 15篇 |
基础医学 | 39篇 |
口腔科学 | 16篇 |
临床医学 | 54篇 |
内科学 | 122篇 |
皮肤病学 | 5篇 |
神经病学 | 23篇 |
特种医学 | 132篇 |
外科学 | 32篇 |
综合类 | 45篇 |
预防医学 | 31篇 |
药学 | 26篇 |
肿瘤学 | 30篇 |
出版年
2022年 | 4篇 |
2021年 | 10篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 8篇 |
2017年 | 9篇 |
2016年 | 6篇 |
2015年 | 9篇 |
2014年 | 10篇 |
2013年 | 16篇 |
2012年 | 19篇 |
2011年 | 12篇 |
2010年 | 14篇 |
2009年 | 17篇 |
2008年 | 13篇 |
2007年 | 23篇 |
2006年 | 18篇 |
2005年 | 15篇 |
2004年 | 7篇 |
2003年 | 6篇 |
2002年 | 10篇 |
2001年 | 3篇 |
2000年 | 7篇 |
1999年 | 12篇 |
1998年 | 23篇 |
1997年 | 41篇 |
1996年 | 45篇 |
1995年 | 23篇 |
1994年 | 25篇 |
1993年 | 25篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 18篇 |
1988年 | 20篇 |
1987年 | 14篇 |
1986年 | 23篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 2篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1976年 | 11篇 |
1975年 | 7篇 |
1972年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有616条查询结果,搜索用时 0 毫秒
41.
Occult malignant breast lesions in 114 patients: relationship to age and the presence of microcalcifications 总被引:2,自引:0,他引:2
Hermann G; Janus C; Schwartz IS; Papatestas A; Hermann DG; Rabinowitz JG 《Radiology》1988,169(2):321-324
This study evaluates the mammographic findings in 352 patients, aged 30-85 years, who underwent spot localization and biopsy for evaluation of nonpalpable breast abnormalities. Malignancy was found at biopsy in 114 cases. The mammographic appearance (specifically, whether grouped microcalcifications, mass, or both were present) was correlated with patient age and histologic findings (specifically, whether the pathologic changes were infiltrating or noninfiltrating in nature). The prevalence of malignant conditions increased directly with age. The presence of grouped microcalcifications as the sole indicator of malignancy was seen in 100% (seven of seven) of the patients in the 30-39-year age group, 64% (18 of 28) in the 40-49-year age group, 37% (11 of 30) in the 50-59-year age group, 30% (seven of 23) in the 60-69-year age group, and 23% (six of 26) in the 70-85-year age group. Of the 49 tumors that were manifested solely as microcalcifications, 34 (69%) were noninfiltrating. The finding of grouped microcalcifications should be aggressively investigated, since it may indicate noninfiltrating carcinoma in an early stage, when the potential for cure is greatest. 相似文献
42.
School Mental Health - Mental health is a major component of overall health and is considered a contributor to the significant levels of disability in Saudi Arabia. Levels of mental health... 相似文献
43.
Does Physical Activity in Adolescence Have Site‐Specific and Sex‐Specific Benefits on Young Adult Bone Size,Content, and Estimated Strength? 下载免费PDF全文
Rachel L Duckham Adam DG Baxter‐Jones James D Johnston Hassanali Vatanparast David Cooper Saija Kontulainen 《Journal of bone and mineral research》2014,29(2):479-486
The long‐term benefits of habitual physical activity during adolescence on adult bone structure and strength are poorly understood. We investigated whether physically active adolescents had greater bone size, density, content, and estimated bone strength in young adulthood when compared to their peers who were inactive during adolescence. Peripheral quantitative computed tomography (pQCT) was used to measure the tibia and radius of 122 (73 females) participants (age mean ± SD, 29.3 ± 2.3 years) of the Saskatchewan Pediatric Bone Mineral Accrual Study (PBMAS). Total bone area (ToA), cortical density (CoD), cortical area (CoA), cortical content (CoC), and estimated bone strength in torsion (SSIp) and muscle area (MuA) were measured at the diaphyses (66% tibia and 65% radius). Total density (ToD), trabecular density (TrD), trabecular content (TrC), and estimated bone strength in compression (BSIc) were measured at the distal ends (4%). Participants were grouped by their adolescent physical activity (PA) levels (inactive, average, and active) based on mean PA Z‐scores obtained from serial questionnaire assessments completed during adolescence. We compared adult bone outcomes across adolescent PA groups in each sex using analysis of covariance followed by post hoc pairwise comparisons with Bonferroni adjustments. When adjusted for adult height, MuA, and PA, adult males who were more physically active than their peers in adolescence had 13% greater adjusted torsional bone strength (SSIp, p < 0.05) and 10% greater adjusted ToA (p < 0.05) at the tibia diaphysis. Females who were more active in adolescence had 10% larger adjusted CoA (p < 0.05), 12% greater adjusted CoC (p < 0.05) at the tibia diaphysis, and 3% greater adjusted TrC (p < 0.05) at the distal tibia when compared to their inactive peers. Benefits to tibia bone size, content, and strength in those who were more active during adolescence seemed to persist into young adulthood, with greater ToA and SSIp in males, and greater CoA, CoC, and TrC in females. © 2014 American Society for Bone and Mineral Research. 相似文献
44.
Monocyte antigen CD14 is a phospholipid anchored membrane protein 总被引:30,自引:1,他引:30
A cDNA clone encoding the human monocyte antigen CD14 was isolated by transient expression in COS cells of a cDNA library prepared from phorbol diester-treated HL60 cells. RNA blot analysis showed abundant expression of a single mRNA species in mature monocytes and an increased expression of the mRNA following induction of differentiation in leukemic cell lines. The DNA blot hybridization pattern was consistent with a single-copy gene. The predicted amino acid sequence lacks the characteristic transmembrane domain and stop transfer motif of conventionally anchored membrane proteins. COS cells transfected with the CD14 cDNA released virtually all CD14 protein in soluble form following treatment with glycosyl phosphatidylinositol-specific phospholipase C, and CD14 immunoreactivity was absent from the affected monocytes of a patient with paroxysmal nocturnal hemoglobinuria (PNH). The data show that, to the limit of experimental sensitivity, all monocyte CD14 is joined to the plasma membrane by a phosphatidylinositol phospholipid. 相似文献
45.
Marsh JC; Will AJ; Hows JM; Sartori P; Darbyshire PJ; Williamson PJ; Oscier DG; Dexter TM; Testa NG 《Blood》1992,79(12):3138-3144
We have used the long-term bone marrow culture (LTBMC) system to analyze hematopoiesis in three patients with dyskeratosis congenita (DC), two of whom had aplastic anemia, and the third had a normal blood count (apart from mild macrocytosis) and normal BM cellularity. Hematopoiesis was severely defective in all three patients, as measured by a low incidence of colony-forming cells and a low level of hematopoiesis in LTBMC. The function of the marrow stroma was normal in its ability to support the growth of hematopoietic progenitors from normal marrows seeded onto them in all three cases, but the generation of hematopoietic progenitors from patients marrow cells inoculated onto normal stromas was reduced, thus suggesting the defect to be of stem cell origin. The parents and unaffected brother of one of the families have also been studied in LTBMC and all showed normal hematopoietic and stromal cell function. From this study we speculate that there are some similarities between DC and the defect in the W/Wv mouse. 相似文献
46.
47.
Amenábar JJ Durán MI Montejo M Lampreabe I 《Nefrología : publicación oficial de la Sociedad Espa?ola Nefrologia》2006,26(2):270-273
The incidence of herpes simplex virus (HSV) encephalitis is estimated to occur annually in 2-4 cases per million population. HSV encephalitis is exceptional in renal transplant patients, we have found two previous reports after an extensive bibliography search. We report a case of a 47 years old women renal transplant recipient who presented 3 months after transplantation fever, stupor and aphasia. The diagnosis HSV encephalitis was achieved by PCR in cerebrospinal fluid and magnetic resonance imaging. She was treated with aciclovir for 4 weeks and recovered completely without neurologic sequelae. 相似文献
48.
49.
Influence of hydroxyurea on fetal hemoglobin production in vitro 总被引:1,自引:0,他引:1
Cytotoxic drugs increase circulating fetal hemoglobin levels. We examined the mechanism by measuring the fetal hemoglobin produced per BFU-E-derived erythroblast following hydroxyurea treatment in vivo and in vitro. Treatment of four sickle cell patients increased the percentage of circulating F reticulocytes. The frequencies of bone marrow or peripheral blood BFU-E or CFU-E-derived colonies and their fetal hemoglobin content were unaffected. In all cases, the number of erythroid cells/progenitor-derived colony increased. To explore further the effect of hydroxyurea on fetal hemoglobin production, we added 50 mumol/L hydroxyurea to cultures of peripheral blood BFU-E-derived erythroblasts on 1 of 9 days (day 5 through 13) to nine samples. These BFU-E were derived from the peripheral blood of normal donors, sickle trait donors, and sickle cell anemia patients and from the bone marrows of monkeys. This concentration of hydroxyurea was selected so that the frequency of BFU-E and their size was moderately decreased. Addition of hydroxyurea to these progenitor-derived erythroid cells had no effect on fetal hemoglobin content per cell. Neither did transient exposure of progenitors to hydroxyurea prior to culture in nontoxic concentrations (0 to 500 mumol/L) result in a significant increase in fetal hemoglobin content in progenitor-derived erythroblasts. These data suggest that hydroxyurea does not directly alter the HbF program expressed by progenitor-derived erythroid cells. Instead, it enhances hemoglobin F content secondarily, possibly by inducing alterations in erythropoiesis. 相似文献
50.
Dziennis S; Van Etten RA; Pahl HL; Morris DL; Rothstein TL; Blosch CM; Perlmutter RM; Tenen DG 《Blood》1995,85(2):319-329
CD11b is the alpha chain of the Mac-1 integrin and is preferentially expressed in myeloid cells (neutrophils, monocytes, and macrophages). We have previously shown that the CD11b promoter directs cell-type- specific expression in myeloid lines using transient transfection assays. To confirm that these promoter sequences contain the proper regulatory elements for correct myeloid expression of CD11b in vivo, we have used the -1.7-kb human CD11b promoter to direct reporter gene expression in transgenic mice. Stable founder lines were generated with two different reporter genes, a Thy 1.1 surface marker and the Escherichia coli lacZ (beta-galactosidase) gene. Analysis of founders generated with each reporter demonstrated that the CD11b promoter was capable of driving high levels of transgene expression in murine macrophages for the lifetime of the animals. Similar to the endogenous gene, transgene expression was preferentially found in mature monocytes, macrophages, and neutrophils and not in myeloid precursors. These experiments indicate that the -1.7 CD11b promoter contains the regulatory elements sufficient for high-level macrophage expression. This promoter should be useful for targeting heterologous gene expression to mature myeloid cells. 相似文献