全文获取类型
收费全文 | 861篇 |
免费 | 51篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 78篇 |
妇产科学 | 5篇 |
基础医学 | 97篇 |
口腔科学 | 12篇 |
临床医学 | 99篇 |
内科学 | 156篇 |
皮肤病学 | 3篇 |
神经病学 | 46篇 |
特种医学 | 157篇 |
外科学 | 103篇 |
综合类 | 9篇 |
预防医学 | 49篇 |
眼科学 | 7篇 |
药学 | 52篇 |
中国医学 | 2篇 |
肿瘤学 | 45篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 10篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 13篇 |
2015年 | 16篇 |
2014年 | 20篇 |
2013年 | 28篇 |
2012年 | 29篇 |
2011年 | 37篇 |
2010年 | 20篇 |
2009年 | 24篇 |
2008年 | 27篇 |
2007年 | 23篇 |
2006年 | 27篇 |
2005年 | 27篇 |
2004年 | 30篇 |
2003年 | 24篇 |
2002年 | 22篇 |
2001年 | 13篇 |
2000年 | 15篇 |
1999年 | 14篇 |
1998年 | 39篇 |
1997年 | 63篇 |
1996年 | 44篇 |
1995年 | 37篇 |
1994年 | 37篇 |
1993年 | 27篇 |
1992年 | 19篇 |
1991年 | 13篇 |
1990年 | 8篇 |
1989年 | 21篇 |
1988年 | 24篇 |
1987年 | 20篇 |
1986年 | 25篇 |
1985年 | 21篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 12篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1978年 | 9篇 |
1977年 | 13篇 |
1976年 | 4篇 |
1975年 | 6篇 |
1970年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有923条查询结果,搜索用时 15 毫秒
881.
M Levin KB Elkon TJ Nokes AM Buckle MJ Dillon RM Hardisty TM Barratt 《Archives of disease in childhood》1983,58(9):703-708
Prostacyclin (PGI2) production was diminished when rat aortic rings were incubated with plasma from 5 of 6 patients with the sporadic form of haemolytic uraemic syndrome but was normal in the presence of plasma from 7 patients with the epidemic form of haemolytic uraemic syndrome or from patients with other renal diseases. The reduced PGI2 production was caused by an unstable inhibitor, extractable into polar lipid solvents, in sporadic haemolytic uraemic plasma. These results suggest that there may be at least 2 different pathogenetic mechanisms in epidemic and sporadic haemolytic uraemic syndrome and that the reduced PGI2 production observed in the sporadic type is due to an inhibitor of PGI2 production rather than a deficiency of stimulating factors. 相似文献
882.
The intake of nutrients over a five day period was studied in 23 children whose atopic eczema was being treated by the avoidance of multiple foods. The results were compared with those from 23 healthy control children not on a diet. Significantly low intakes of calcium were discovered in 13 patients but not in controls. Avoidance of multiple foods is potentially hazardous and requires continued paediatric and dietetic supervision. 相似文献
883.
Shigemasa K Tanimoto H Sakata K Nagai N Parmley TH Ohama K O'Brien TJ 《Medical oncology (Northwood, London, England)》2000,17(1):52-58
Matrix metalloproteases are known to play an important role in tumor invasion by mediating degradation of the extracellular
matrix. In this study, we have investigated the immunohistochemical expression of matrix metalloprotease-7 (MMP-7) in 44 mucinous
ovarian tumors (9 adenomas, 13 low malignant potential tumors, 22 adenocarcinomas) and 6 normal ovaries. Positive staining
of MMP-7 is observed in all mucinous ovarian tumors, whereas little or no staining was observed in surface epithelium as well
as the epithelial cells of germinal inclusion cyst of the normal ovary. Positive immunostaining of MMP-7 is also observed
in the secreted mucin in the tumor glands, which suggests the secretion of the MMP-7 protein from tumor cells. mRNA expression
of MMP-7 was confirmed using RT-PCR. The MMP-7 gene was amplified in parallel with an internal control gene β-tubulin using
a thermal cycler. mRNA expression levels of MMP-7 were significantly elevated in mucinous tumor samples compared with that
in normal ovaries. Our results suggest that MMP-7 is frequently overexpressed in mucinous ovarian tumors and secreted with
the mucin which is produced from the tumor cells. MMP-7 may therefore contribute to mucinous ovarian tumor development or
enhanced growth capacity of mucinous ovarian tumors. MMP-7 may also serve as a target for therapeutic intervention in the
down regulation of tumor progression. 相似文献
884.
Lower esophageal sphincter pressures and serum gastrin levels after cholinergic stimulation 总被引:2,自引:0,他引:2
Higgs RH; Humphries TJ; Castell DO; McGuigan JE 《The American journal of physiology》1976,231(4):1250-1253
885.
The gene for schnyder's crystalline corneal dystrophy maps to human chromosome 1p34.1-p36 总被引:3,自引:0,他引:3
Shearman AM; Hudson TJ; Andresen JM; Wu X; Sohn RL; Haluska F; Housman DE; Weiss JS 《Human molecular genetics》1996,5(10):1667-1672
Schnyder's crystalline corneal dystrophy (SCCD) is an autosomal dominant
eye disease characterized by a bilateral clouding of the central cornea,
arcus lipoides and/or visible crystalline deposits of cholesterol in the
stroma. There is accumulation of phospholipid, unesterified cholesterol and
cholesterol ester in the corneal stroma; this is believed to be due to an
imbalance in the local factors affecting lipid/cholesterol transport or
metabolism. The cellular mechanism of abnormal lipid transport and
metabolism in SCCD is of interest due to its potential involvement in
atherosclerosis, and its implications for the pathogenesis of
cerebrovascular, coronary and peripheral vascular disease as well as
corneal opacification. To determine the chromosomal location of the SCCD
locus, genome-wide linkage analysis has been performed in two large
Swede-Finn kindreds recently identified in central Massachusetts. After
analysing 300 microsatellite markers > 90% of the genome was excluded
from linkage to the SCCD locus. We now report the chromosomal assignment of
the gene for SCCD in both families to be 1p34.1-p36; the maximum multipoint
lod- score was 8.48 in the interval between D1S214 and D1S503. From
haplotype analysis, the SCCD locus lies in the 16 cM interval between
markers D1S2663 and D1S228. Several candidate genes for SCCD have been
localized to the 1p34.1-p36 interval.
相似文献
886.
Clonogenicity of circulating neuroblastoma cells: implications regarding peripheral blood stem cell transplantation 总被引:1,自引:0,他引:1
Peripheral blood stem cells (PBSCs) are being used as an alternative to autologous marrow rescue for hematopoietic reconstitution after high- dose chemotherapy in patients with neuroblastoma and other solid malignancies. Use of PBSCs is preferred by some because of the belief that there is less risk of tumor contamination. Because tumor stem cell contamination is thought to be one contributing cause of relapse after myeloablative therapy and autologous reconstitution, we examined the potential risk of reinfusing circulating neuroblastoma cells by in vitro evaluation of their clonogenicity. Immunocytologic and tumor cell clonogenic analyses were performed on 74 blood samples obtained from 56 children with advanced-stage neuroblastoma. Concurrently drawn bone marrow specimens were evaluated in 30 instances. Circulating neoplastic cells were detected in 19 of 74 (26%) for all specimens and by immunologic techniques (26%). Using a clonogenic assay, 13 grew identifiable tumor colonies. Comparing results with the two techniques showed tumor colony growth in 10 of the 19 positive specimens by immunocytology. However, 3 of 53 samples (6%) that were negative by immunocytology were positive by the clonogenic assay. Of the 11 positive blood samples, 9 concurrent marrows contained neuroblastoma cells; of the 19 negative blood specimens, 3 concurrent marrows had metastatic disease. We conclude that circulating neuroblastoma cells are present in peripheral blood and have clonogenic properties in vitro. This supports the view that tumor cell contamination may well be one cause of relapse after autologous reconstitution. Consequently, PBSC collections should also undergo meticulous monitoring for tumor contamination before autologous reinfusion. 相似文献
887.
Cytokine-specific regulation of urokinase receptor (CD87) expression by U937 mononuclear phagocytes 总被引:7,自引:0,他引:7
Sitrin RG; Todd RF rd; Mizukami IF; Gross TJ; Shollenberger SB; Gyetko MR 《Blood》1994,84(4):1268-1275
Mononuclear phagocytes concentrate urokinase-type plasminogen activator (uPA) at the cell surface by expressing membrane uPA receptors (uPAR). This study examines the ability of exogenous cytokines to alter expression of membrane-associated uPA and uPAR in U937 mononuclear phagocytes. Cells were stimulated with recombinant interferon gamma (IFN gamma) or tumor necrosis factor alpha (TNF alpha), followed by immunolabeling for uPA or uPAR and flow cytometry. IFN gamma increased surface uPA 2.2-fold relative to unstimulated controls (P < .001), whereas TNF alpha had no significant effect. Likewise, maximal uPA binding capacity was increased 2.8-fold by IFN gamma (P < .02), but was not affected by TNF alpha. In unstimulated cells, 50% of receptors were occupied by endogenously generated uPA, and this proportion was not affected by either cytokine. IFN gamma upregulated uPAR 2.1-fold relative to unstimulated controls (P < .001), whereas TNF alpha had no effect. In contrast to effects on surface protein, TNF alpha induced a substantial increase in uPAR mRNA, equaling the effect of IFN gamma. In addition, both cytokines doubled the intracellular uPAR pool (P < .01). By contrast, TNF alpha induced a 2.5-fold increase in the level of uPAR protein released into conditioned medium (compared with unstimulated cells), whereas IFN gamma had no effect. These results indicate that uPAR expression is regulated in a cytokine-specific fashion. Some stimuli, such as TNF alpha, may increase uPAR synthetic activity without a corresponding change in membrane expression, because of enhanced release of uPAR from the cell. Cytokine-specific modulation of uPAR may be important in regulating the function of mononuclear phagocytes in inflammation and tissue repair. 相似文献
888.
Expression of latent hematopoietic progenitor cells in cultures of newborn and adult baboon liver 总被引:1,自引:0,他引:1
The anatomic site of hematopoiesis changes during fetal development from the yolk sac to the liver and finally to the marrow. Factors controlling this switch in the site of hematopoiesis are unknown. We assayed erythroid colony (CFU-E) and erythroid burst (BFU-E) formation in fetal, newborn, and adult baboon liver and marrow to determine the growth requirements of primate hematopoietic progenitor cells from different anatomic sites and developmental stages. We cocultured fetal, newborn, and adult liver and marrow nonadherent cells with adherent cells from these organs to assess the role adherent cells may play in determining the site of hematopoiesis. Fetal liver, fetal marrow, newborn marrow, and adult marrow cultures formed CFU-E and BFU-E colonies in vitro. In contrast, newborn and adult liver cell cultures very rarely formed colonies. However, when newborn or adult liver nonadherent cells were cocultured with marrow adherent cells, CFU-E and BFU-E colonies were detected. The colonies that formed in the newborn and adult liver cultures were derived from the liver and not from the marrow cells or peripheral blood trapped in the liver. These data suggest that in contrast to fetal liver, newborn and adult liver may not be hematopoietic organs in normal primates in vivo because of changes in the growth requirements of hematopoietic progenitor cells present in these organs. 相似文献
889.
OJ Old SR Kulkarni TJ Hardy FJ Slim LG Emerson RA Bulbulia MR Whyman KR Poskitt 《Annals of the Royal College of Surgeons of England》2015,97(2):120-124
Introduction
Totally extra-peritoneal (TEP) inguinal hernia repair allows identification and repair of incidental non-inguinal groin hernias. We assessed the prevalence of incidental hernias during TEP inguinal hernia repair and identified the risk factors for incidental hernias.Materials and Methods
Consecutive patients undergoing TEP repair from May 2005 to November 2012 were the study cohort. Inspection for ipsilateral femoral, obturator and rarer varieties of hernia was undertaken during TEP repair. Patient characteristics and operative findings were recorded on a prospectively collected database.Results
A total of 1,532 TEP repairs were undertaken in 1,196 patients. Ninety-three patients were excluded due to incomplete data, leaving 1,103 patients and 1,404 hernias for analyses (1,380 male; 802 unilateral and 301 bilateral repairs; median age, 59 years). Among the 37 incidental hernias identified (2.6% of cases), the most common type of incidental hernia was femoral (n=32, 2.3%) followed by obturator (n=2, 0.1%). Increasing age was associated with an increased risk of incidental hernia, with a significant linear trend (p<0.01). The risk for patients >60 years of age was 4.0% vs 1.4% for those aged <60 years (p<0.01). Incidental hernias were found in 29.2% of females vs 2.2% of males, (p<0.0001). Risk of incidental hernia in those with a recurrent inguinal hernia was 3.0% vs 2.6% for primary repair (p=0.79).Conclusions
Incidental hernias during TEP inguinal hernia repair were found in 2.6% of cases and, though infrequent, could cause complications if left untreated. The risk of incidental hernia increased with age and was significantly higher in patients aged >60 years and in females. 相似文献890.
Marcos Gradim Tiveron Helton Augusto Bomfim Maycon Soto Simplício Marcos Henriques Bergonso Milena Paiva Brasil de Matos Sergio Marques Ferreira Eraldo Ant?nio Pelloso Rubens Tofano de Barros 《Brazilian Journal Of Cardiovascular Surgery》2015,30(1):1-8