全文获取类型
收费全文 | 3640篇 |
免费 | 258篇 |
国内免费 | 21篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 116篇 |
妇产科学 | 83篇 |
基础医学 | 383篇 |
口腔科学 | 136篇 |
临床医学 | 463篇 |
内科学 | 637篇 |
皮肤病学 | 126篇 |
神经病学 | 335篇 |
特种医学 | 282篇 |
外科学 | 498篇 |
综合类 | 127篇 |
一般理论 | 2篇 |
预防医学 | 280篇 |
眼科学 | 35篇 |
药学 | 212篇 |
中国医学 | 1篇 |
肿瘤学 | 195篇 |
出版年
2021年 | 55篇 |
2020年 | 34篇 |
2019年 | 67篇 |
2018年 | 60篇 |
2017年 | 45篇 |
2016年 | 51篇 |
2015年 | 58篇 |
2014年 | 67篇 |
2013年 | 98篇 |
2012年 | 163篇 |
2011年 | 167篇 |
2010年 | 121篇 |
2009年 | 118篇 |
2008年 | 159篇 |
2007年 | 177篇 |
2006年 | 186篇 |
2005年 | 167篇 |
2004年 | 150篇 |
2003年 | 148篇 |
2002年 | 140篇 |
2001年 | 134篇 |
2000年 | 161篇 |
1999年 | 88篇 |
1998年 | 59篇 |
1997年 | 54篇 |
1996年 | 61篇 |
1995年 | 46篇 |
1994年 | 37篇 |
1993年 | 47篇 |
1992年 | 65篇 |
1991年 | 63篇 |
1990年 | 56篇 |
1989年 | 69篇 |
1988年 | 56篇 |
1987年 | 64篇 |
1986年 | 51篇 |
1985年 | 60篇 |
1984年 | 43篇 |
1983年 | 34篇 |
1981年 | 26篇 |
1979年 | 28篇 |
1978年 | 30篇 |
1977年 | 25篇 |
1975年 | 20篇 |
1972年 | 23篇 |
1971年 | 24篇 |
1970年 | 23篇 |
1969年 | 21篇 |
1968年 | 22篇 |
1967年 | 24篇 |
排序方式: 共有3919条查询结果,搜索用时 140 毫秒
81.
Cytogenetic and histologic correlations in malignant lymphoma 总被引:9,自引:0,他引:9
Koduru PR; Filippa DA; Richardson ME; Jhanwar SC; Chaganti SR; Koziner B; Clarkson BD; Lieberman PH; Chaganti RS 《Blood》1987,69(1):97-102
Although a number of studies have indicated correlations between histologic subtypes of tumors and certain nonrandom chromosome changes, cytogenetic studies of lymphoma are in an early stage compared to those of leukemia. No comprehensive analysis of available data has so far been attempted in the literature either. Here we present an analysis of chromosome changes and their correlation with subtypes of lymphoma studied by conventional histology and cell surface markers, as observed in two sets of data: a group of 65 karyotypically abnormal tumors sequentially ascertained and studied by us during the period January 1, 1984 to April 30, 1985, and a larger data set derived by combining our data with those from two published series from the University of Minnesota that are comparable to our data. These combined data, which comprise the largest data set on the cytogenetics of lymphomas assembled so far, enabled a comprehensive analysis of correlation between chromosome change and tumor histology and the patterns of chromosome instability in these tumors. We found several significant associations, some previously described and others now recognized, between nonrandom chromosome gains, breaks, translocations, and deletions and histologic subtypes of tumors that characterize lymphomas. The data indicate that finding of chromosome breaks at certain sites (eg, 8q24, 14q32, 18q21) is of diagnostic value in dealing with cases of unusual lymphoma. Furthermore, nonrandom chromosome breakage exhibited three distinct patterns that reflected three levels of etiologically relevant genetic change. 相似文献
82.
Predicted hexameric structure of the Agrobacterium VirB4 C terminus suggests VirB4 acts as a docking site during type IV secretion
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Middleton R Sjölander K Krishnamurthy N Foley J Zambryski P 《Proceedings of the National Academy of Sciences of the United States of America》2005,102(5):1685-1690
The Agrobacterium T-DNA transporter belongs to a growing class of evolutionarily conserved transporters, called type IV secretion systems (T4SSs). VirB4, 789 aa, is the largest T4SS component, providing a rich source of possible structural domains. Here, we use a variety of bioinformatics methods to predict that the C-terminal domain of VirB4 (including the Walker A and B nucleotide-binding motifs) is related by divergent evolution to the cytoplasmic domain of TrwB, the coupling protein required for conjugative transfer of plasmid R388 from Escherichia coli. This prediction is supported by detailed sequence and structure analyses showing conservation of functionally and structurally important residues between VirB4 and TrwB. The availability of a solved crystal structure for TrwB enables the construction of a comparative model for VirB4 and the prediction that, like TrwB, VirB4 forms a hexamer. These results lead to a model in which VirB4 acts as a docking site at the entrance of the T4SS channel and acts in concert with VirD4 and VirB11 to transport substrates (T-strand linked to VirD2 or proteins such as VirE2, VirE3, or VirF) through the T4SS. 相似文献
83.
J. Brendan Foley Kumar Sridhar John Dawdy Chris Konstantinou Robert I. G. Brown Ian M. Penn 《Catheterization and cardiovascular interventions》1994,31(4):264-269
Prolonged inflation with perfusion balloons is commonly used in failed angioplasty. The objective of this study was to determine the angiographic outcome of 59 consecutive patients treated with prolonged inflation with perfusion balloons as the primary treatment for failed angioplasty. Angiographic success (< 50% stenosis and normal flow) was achieved in 41%. Angiographic success was greater in the left anterior descending coronary artery (67% versus 33% for non-left anterior descending involvement, P = .044) and was less in complex dissections (25% versus 75% for no dissection or simple dissections, P = .025). Angiographic deterioration occurred in 37.5% of the successful group and 77% of the unsuccessful group (P = .002) and was more frequent in the right coronary artery (88% versus 50% for non-right coronary involvement, P = .007) and complex dissections (92% versus 38% for no dissection or simple dissections, P = .0001). Thus, in a group of patients with unsuccessful outcome following conventional balloon angioplasty, success with the perfusion balloon was modest. Furthermore, angiographic deterioration was frequently observed following unsuccessful prolonged inflation. 相似文献
84.
The risk of nursing home admission in three communities 总被引:3,自引:0,他引:3
Foley DJ Ostfeld AM Branch LG Wallace RB McGloin J Cornoni-Huntley JC 《Journal of aging and health》1992,4(2):155-173
Beginning in 1982, the 3-year incidence of nursing home admission was determined for community-dwelling residents aged 65 and over in East Boston, Massachusetts (4%); New Haven, Connecticut (9%); and Iowa and Washington Counties, Iowa (12%). A common methodology was used to collect baseline risk factor and follow-up data on nursing home admissions among persons in each community as part of the National Institute on Aging's Established Populations for Epidemiologic Studies of the Elderly. A multivariate logistic regression model of baseline risk factors that included the participant's age, race, sex, history of prior admission, ADL limitations, cognitive function, living arrangements, and level of income predicted 80% of the users in each community. 相似文献
85.
Regulation of stimulated integrin surface expression in human neutrophils by tyrosine phosphorylation 总被引:4,自引:0,他引:4
The control of the adhesive properties of human neutrophils is an essential element of their defense function. One level at which this control is exerted involves the upregulation of the surface expression of beta 2-integrins. In this study, we have examined the potential involvement of tyrosine phosphorylation in the latter process. Two inhibitors of tyrosine kinases with differing modes of action, erbstatin and herbimycin A, were found to inhibit the expression of CD11b and CD18 stimulated by chemotactic factors (fMet-Leu-Phe or leukotriene B4) or growth factors (tumor necrosis factor alpha). This inhibition was not shared by an inactive analog of erbstatin or by the protein kinase C inhibitor Ro 31-8330. Erbstatin also inhibited the unveiling of activation-specific neoepitopes detected by antibody CBRM1/5. Pretreatment of neutrophils (but not of endothelial cells) with erbstatin inhibited the stimulation of neutrophils' adherence to endothelial cells induced by fMet-Leu-Phe. Augmentation of tyrosine phosphorylation by inhibiting tyrosine phosphatases using hydroperoxyvanadate led to an increased surface expression of CD11b and CD18 and enhanced the adhesion of neutrophils to endothelial cells. Finally, the leumedin NPC 15669, which had previously been shown to inhibit stimulated CD11b expression and neutrophil adherence to endothelial cells and to exhibit anti-inflammatory properties in various in vivo models of inflammation, inhibited the stimulation of tyrosine, phosphorylation induced by fMet-Leu-Phe. Taken together, these data establish a strong correlation between tyrosine phosphorylation and integrin upregulation in stimulated human neutrophils. 相似文献
86.
Molloy K; Goulden N; Lawler M; Cornish J; Oakhill A; Pamphilon D; Potter M; Steward C; Langlands K; Humphries P; McCann SR 《Blood》1996,87(7):3027-3031
Hematopoietic chimerism was analyzed in serial bone marrow samples taken from 28 children following T-cell depleted unrelated donor bone marrow transplants (UD BMT) for acute lymphoblastic leukemia (ALL). Chimeric status was determined by polymerase chain reaction (PCR) of simple tandem repeat (STR) sequences (maximal sensitivity, 0.1%). At least two serial samples were examined in 23 patients. Of these, two had evidence of complete donor engraftment at all times and eight showed stable low level mixed chimerism (MC) (<1% recipient hematopoiesis). All 10 of these patients remain in remission with a minimum follow-up of 24 months. By contrast, 13 patients demonstrated a progressive return of recipient hematopoiesis. Five of these relapsed (4 to 9 months post BMT), one died of cytomegalovirus pneumonitis and seven remain in remission with a minimum follow-up of 24 months. Five children were excluded from serial analysis as two serial samples were not collected before either relapse (3) or graft rejection (2). We conclude that as with sibling transplants, ex vivo T depleted UD BMT in children with ALL is associated with a high incidence of MC. Stable donor engraftment and low level MC always correlated with continued remission. However, detection of a progressive return of recipient cells did not universally correlate with relapse, but highlighted those patients at greatest risk. Serial chimerism analysis by PCR of STRs provides a rapid and simple screening technique for the detection of relapse and the identification of patients with progressive MC who might benefit from detailed molecular analysis for minimal residual disease following matched volunteer UD BMT for childhood ALL. 相似文献
87.
Mosaicism for Dominant Collagen 6 Mutations as a Cause for Intrafamilial Phenotypic Variability
下载免费PDF全文
![点击此处可从《Human mutation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Sandra Donkervoort Ying Hu Tanya Stojkovic Nicol C. Voermans A. Reghan Foley Meganne E. Leach Jahannaz Dastgir Véronique Bolduc Thomas Cullup Alix de Becdelièvre Lin Yang Hai Su Katherine Meilleur Alice B. Schindler Erik‐Jan Kamsteeg Pascale Richard Russell J. Butterfield Thomas L. Winder Thomas O. Crawford Robert B. Weiss Francesco Muntoni Valérie Allamand Carsten G. Bönnemann 《Human mutation》2015,36(1):48-56
Collagen 6‐related dystrophies and myopathies (COL6‐RD) are a group of disorders that form a wide phenotypic spectrum, ranging from severe Ullrich congenital muscular dystrophy, intermediate phenotypes, to the milder Bethlem myopathy. Both inter‐ and intrafamilial variable expressivity are commonly observed. We present clinical, immunohistochemical, and genetic data on four COL6‐RD families with marked intergenerational phenotypic heterogeneity. This variable expression seemingly masquerades as anticipation is due to parental mosaicism for a dominant mutation, with subsequent full inheritance and penetrance of the mutation in the heterozygous offspring. We also present an additional fifth simplex patient identified as a mosaic carrier. Parental mosaicism was confirmed in the four families through quantitative analysis of the ratio of mutant versus wild‐type allele (COL6A1, COL6A2, and COL6A3) in genomic DNA from various tissues, including blood, dermal fibroblasts, and saliva. Consistent with somatic mosaicism, parental samples had lower ratios of mutant versus wild‐type allele compared with the fully heterozygote offspring. However, there was notable variability of the mutant allele levels between tissues tested, ranging from 16% (saliva) to 43% (fibroblasts) in one mosaic father. This is the first report demonstrating mosaicism as a cause of intrafamilial/intergenerational variability of COL6‐RD, and suggests that sporadic and parental mosaicism may be more common than previously suspected. 相似文献
88.
89.
90.