全文获取类型
收费全文 | 18663篇 |
免费 | 1503篇 |
国内免费 | 52篇 |
专业分类
耳鼻咽喉 | 136篇 |
儿科学 | 652篇 |
妇产科学 | 473篇 |
基础医学 | 2985篇 |
口腔科学 | 241篇 |
临床医学 | 2164篇 |
内科学 | 3427篇 |
皮肤病学 | 378篇 |
神经病学 | 2165篇 |
特种医学 | 404篇 |
外科学 | 2160篇 |
综合类 | 84篇 |
一般理论 | 23篇 |
预防医学 | 2026篇 |
眼科学 | 314篇 |
药学 | 1116篇 |
中国医学 | 32篇 |
肿瘤学 | 1438篇 |
出版年
2024年 | 35篇 |
2023年 | 213篇 |
2022年 | 417篇 |
2021年 | 805篇 |
2020年 | 505篇 |
2019年 | 704篇 |
2018年 | 716篇 |
2017年 | 577篇 |
2016年 | 622篇 |
2015年 | 663篇 |
2014年 | 844篇 |
2013年 | 1157篇 |
2012年 | 1636篇 |
2011年 | 1617篇 |
2010年 | 763篇 |
2009年 | 724篇 |
2008年 | 1239篇 |
2007年 | 1196篇 |
2006年 | 1073篇 |
2005年 | 1050篇 |
2004年 | 974篇 |
2003年 | 841篇 |
2002年 | 724篇 |
2001年 | 118篇 |
2000年 | 61篇 |
1999年 | 95篇 |
1998年 | 127篇 |
1997年 | 107篇 |
1996年 | 70篇 |
1995年 | 62篇 |
1994年 | 53篇 |
1993年 | 45篇 |
1992年 | 37篇 |
1991年 | 27篇 |
1990年 | 28篇 |
1989年 | 26篇 |
1988年 | 20篇 |
1987年 | 28篇 |
1986年 | 16篇 |
1985年 | 17篇 |
1984年 | 15篇 |
1983年 | 20篇 |
1982年 | 26篇 |
1981年 | 20篇 |
1980年 | 21篇 |
1979年 | 12篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1974年 | 7篇 |
1968年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
91.
Lena Möbus Elke Rodriguez Inken Harder Agatha Schwarz Ulrike Wehkamp Dora Stölzl Nicole Boraczynski Sascha Gerdes Thomas Litman Andreas Kleinheinz Susanne Abraham Annice Heratizadeh Christiane Handrick Eva Haufe Jochen Schmitt Thomas Werfel Stephan Weidinger 《The Journal of allergy and clinical immunology》2021,147(5):1959-1965.e2
92.
93.
Anastase-Ravion S Blondin C Cholley B Haeffner-Cavaillon N Castellot JJ Letourneur D 《Journal of biomedical materials research. Part A》2003,66(2):376-384
The glycosaminoglycan heparin is known to exhibit anti-inflammatory properties unrelated to its anticoagulant activity. However, in a generalized inflammatory response with implanted or extracorporeal devices, the beneficial effect of heparin coating and/or systemic administration is still unclear as well as the precise mechanisms of action. In the present study, we have first studied the effect of heparin on lipopolysaccharide (LPS)-induced cytokine production by human blood monocytes. Our results indicated that the production of interleukin-1alpha, tumor necrosis factor-alpha, and interleukin-8 was significantly decreased when heparin was simultaneously incubated with Escherichia coli LPS. Because the modulation of heparin on monocyte activation could be mediated by its binding via CD14, the main LPS receptor on monocytes, we then studied the binding of LPS and heparin to leukocytes from human blood and to Chinese hamster ovary cells transfected with the human CD14 gene. The data by flow cytometry showed the binding of biotinylated heparin to leukocytes. Moreover, the experiments performed on leukocytes and on CD14-positive Chinese hamster ovary cells indicated that heparin inhibited LPS binding. From our results, we conclude that: 1. heparin is an effective inhibitor of LPS-induced monocyte activation, and 2. heparin inhibits the binding of LPS to cells via a CD14-independent pathway. This study suggests a potentially important therapeutic application for heparin or heparin analogs to prevent inflammation with biomaterials. 相似文献
94.
95.
Mauve: multiple alignment of conserved genomic sequence with rearrangements 总被引:14,自引:3,他引:14
下载免费PDF全文
![点击此处可从《Genome research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
As genomes evolve, they undergo large-scale evolutionary processes that present a challenge to sequence comparison not posed by short sequences. Recombination causes frequent genome rearrangements, horizontal transfer introduces new sequences into bacterial chromosomes, and deletions remove segments of the genome. Consequently, each genome is a mosaic of unique lineage-specific segments, regions shared with a subset of other genomes and segments conserved among all the genomes under consideration. Furthermore, the linear order of these segments may be shuffled among genomes. We present methods for identification and alignment of conserved genomic DNA in the presence of rearrangements and horizontal transfer. Our methods have been implemented in a software package called Mauve. Mauve has been applied to align nine enterobacterial genomes and to determine global rearrangement structure in three mammalian genomes. We have evaluated the quality of Mauve alignments and drawn comparison to other methods through extensive simulations of genome evolution. 相似文献
96.
Lohm S Peduto-Eberl L Lagadec P Renggli-Zulliger N Dudler J Jeannin JF Juillerat-Jeanneret L 《Clinical & experimental metastasis》2005,22(4):341-349
It is recognised that stromal cells determine cancer progression. We have previously shown that active TGFβ produced by rat colon carcinoma cells modulated NO production in rat endothelial cells. To elucidate the role of TGFβ and NO in the mechanisms of interaction of colon carcinoma cells with stromal cells and in cancer progression, we transfected
REGb cells, a regressive colon carcinoma clone secreting latent TGFβ, with a cDNA encoding for a constitutively-secreted active TGFβ. Out of 20 injected rats only one tumour progressed, which was resected and sub-cultured (ReBeta cells). ReBeta cells secreted
high levels of active TGFβ. The adhesive properties of REGb and Rebeta cells to endothelial cells were similar, showing that the secretion of active
TGFβ is not involved in tumour cell adhesion to endothelial cells. ReBeta, but not REGb, cell culture supernatants inhibited cytokine-dependent
NO secretion by endothelial cells, but inhibition of NO production was similar in co-cultures of REGb or ReBeta cells with
endothelial cells. Therefore, secretion of active TGFβ regulated endothelial NO synthase activity when tumour cells were distant from, but not in direct contact with, endothelial
cells. However, only ReBeta cells inhibited cytokine-dependent secretion of NO in coculture with macrophages, indicating that
the active-TGFβ–NO axis confers an advantage for tumour cells in their interaction with macrophages rather than endothelial cells in cancer
progression. 相似文献
97.
Cl udia M. D. da Silva Henrique B. Ferreira Marina Pic n Nicole Gorfinkiel Ricardo Ehrlich Arnaldo Zaha 《Molecular and biochemical parasitology》1993,60(2):209-219
An Echinococcus granulosus genomic library has been screened with a mouse β-actin cDNA probe. Two clones carrying DNA fragments of about 15 kb, possibly derived from the same genome region, have been isolated. This 15-kb genomic region includes 2 actin-related sequences (EgactI and EgactII) separated by about 4 kb. The nucleotide sequences of both genes were determined. The EgactI sequence presents no introns, but an intron of 591 bp was observed in the EgactII sequence. The genes potentially encode 375 and 376 amino-acid-long actins, respectively, with a homology of 85.3%. The deduced amino acid sequences from both genes were compared to the actin sequences from other organisms, showing similarities ranging from 63.5% to 90.6%. The nucleotide sequence of a partial actin cDNA clone has been determined. The deduced amino acids sequence showed a homology of 90.3% and 88.0% in relation to the EgactI and EgactII sequences respectively, suggesting the existence of at least one more actin gene in E. granulosus. This hypothesis is reinforced by the number of bands detected in the Southern blot analysis. Experiments based on the amplification of DNA segments using 3′-specific actin primers indicate that the EgactI gene is transcribed in protoscoleces. 相似文献
98.
Zitterkopf NL Jones QA Bradley DS Durick K Rowland RR Plagemann PG Cafruny WA 《Viral immunology》2003,16(4):511-523
Persistent infection of mice with lactate dehydrogenase-elevating virus (LDV) is associated with polyclonal B cell activation, autoimmunity, and circulating hydrophobic IgG-containing immune complexes (ICs), which bind to the surfaces of uncoated ELISA plates in the presence of 0.05% Tween 20. We demonstrate here that hydrophobic IgG-containing ICs also appear naturally in the plasma of autoimmune MRL/lpr mice. These and the similar hydrophobic ICs of LDV-infected mice as well as pigs coincide on ELISA plate surfaces with TGF-beta, apparently in the form of an IgG-TGF-beta complex. Circulating hydrophobic IgG-containing ICs are also susceptible to considerable amplification in vitro by exposure to alkaline conditions. By this latter method, the fraction of in vivo hydrophobic IgG, relative to the maximum in vitro chemically inducible IgG, was found to be about 20% in the plasma of LDV-infected mice, 5% in normal mouse plasma, and less than about 2% in pig plasma. These results indicate the potential for both chemically induced and protein-binding contributions to the generation of hydrophobic IgG-containing molecules, and have implications for immunopathological mechanisms in autoimmunity and persistent virus infections. 相似文献
99.
Robert Weis Nicole L Wilson Savannah M Whitemarsh 《Journal of clinical child and adolescent psychology》2005,34(4):692-705
This study evaluated the effectiveness of a military-style residential treatment program for adolescents with academic and conduct problems. Two hundred twelve referred adolescents were separated into 3 groups for analyses: (a) adolescents who completed the 22-week program, (b) adolescents who prematurely withdrew, and (c) wait-list controls. Adolescents' socioemotional and behavioral functioning were measured at baseline and 6 months after treatment. Results showed statistically and clinically significant reductions in externalizing symptoms and increases in adaptive behavior associated with treatment. Treatment was also associated with increased likelihood of high school completion or employment and decreased likelihood of alcohol or drug problems and arrest. The relation between treatment participation and outcomes was moderated by adolescents' living environments after treatment, but it was not moderated by age of symptom onset. The benefits of treatment may be partially attributable to the voluntary nature of the intervention. 相似文献
100.
Angiopoietin-1 causes reversible degradation of the portal microcirculation in mice: implications for treatment of liver disease
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ward NL Haninec AL Van Slyke P Sled JG Sturk C Henkelman RM Wanless IR Dumont DJ 《The American journal of pathology》2004,165(3):889-899
In many different liver diseases, such as cirrhosis, degradation of the microcirculation, including obliteration of small portal or hepatic veins contributes to disease-associated portal hypertension. The present study demonstrates the importance of angiogenesis in the establishment of arteriovenous shunts and the accompanying changes to the venous bed. One aspect of angiogenesis involves the branching of new vessels from pre-existing ones, and the molecular mechanisms controlling it are complex and involve a coordinated effort between specific endothelial growth factors and their receptors, including the angiopoietins. We modulated the hepatic vasculature in mice by conditionally expressing angiopoietin-1 in hepatocytes. In mice exposed to angiopoietin-1 during development, arterial sprouting, enlarged arteries, marked loss of portal vein radicles, hepatic vein dilation, and suggestion of arteriovenous shunting were observed. Most importantly, these phenotypic changes were completely reversed within 14 days of turning off transgene expression. Expression of excess angiopoietin-1 beginning in adulthood did not fully recapitulate the phenotype, but did result in enlarged vessels. Our findings suggest that controlling excessive angiogenesis during liver disease may promote the restoration of the portal vein circuit and aid in the resolution of disease-associated portal hypertension. 相似文献