首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   326篇
  免费   24篇
  国内免费   2篇
耳鼻咽喉   7篇
儿科学   15篇
基础医学   81篇
口腔科学   24篇
临床医学   28篇
内科学   86篇
皮肤病学   1篇
神经病学   27篇
特种医学   2篇
外科学   21篇
预防医学   18篇
眼科学   3篇
药学   26篇
肿瘤学   13篇
  2023年   1篇
  2022年   2篇
  2021年   3篇
  2020年   2篇
  2019年   5篇
  2018年   5篇
  2017年   3篇
  2016年   5篇
  2015年   6篇
  2014年   3篇
  2013年   7篇
  2012年   10篇
  2011年   14篇
  2010年   12篇
  2009年   8篇
  2008年   15篇
  2007年   16篇
  2006年   19篇
  2005年   21篇
  2004年   25篇
  2003年   30篇
  2002年   26篇
  2001年   11篇
  2000年   6篇
  1999年   11篇
  1998年   5篇
  1997年   8篇
  1996年   9篇
  1995年   3篇
  1994年   5篇
  1993年   8篇
  1992年   6篇
  1991年   6篇
  1990年   5篇
  1989年   6篇
  1988年   2篇
  1987年   5篇
  1986年   3篇
  1985年   3篇
  1984年   2篇
  1983年   4篇
  1982年   1篇
  1980年   2篇
  1978年   1篇
  1977年   2篇
排序方式: 共有352条查询结果,搜索用时 31 毫秒
91.
In this study, we describe the cytological and cytogenetic features of six Epstein-Barr virus (EBV)-infected natural killer (NK) cell clones. Three cell clones, SNK-1, -3 and -6, were derived from patients with nasal T/NK-cell lymphomas; two cell clones, SNK-5 and -10, were isolated from patients with chronic active EBV infection (CAEBV); and the other cell clone, SNK-11, was from a patient with hydroa vacciniforme (HV)-like eruptions. An analysis of the number of EBV-terminal repeats showed that the SNK cell clones had monoclonal EBV genomes identical to the original EBV-infected cells of the respective patients, and SNK cells had the type II latency of EBV infection, suggesting that not only the cell clones isolated from nasal T/NK-cell lymphomas but also those isolated from CAEBV and HV-like eruptions had been transformed by EBV to a certain degree. Cytogenetic analysis detected deletions in chromosome 6q in five out of the six SNK cell clones, while 6q was not deleted in four control cell lines of T-cell lineage. This suggested that a 6q deletion is a characteristic feature of EBV-positive NK cells, which proliferated in the diseased individuals. The results showed that EBV-positive NK cells in malignant and non-malignant lymphoproliferative diseases shared common cytological and cytogenetic features.  相似文献   
92.
Vascular cell adhesion molecule-1 (VCAM-1) and reactive oxygen species play critical roles in early atherogenesis, and nitric oxide (NO) is an important regulator of the cardiovascular system. Although celiprolol, a specific beta1-antagonist with weak beta2-agonistic action, stimulates endothelial nitric oxide synthase (eNOS) production, the mechanisms remain to be determined. Because it was recently reported that phosphatidylinositol 3-kinase (PI3K) and its downstream effector Akt are implicated in the activation of eNOS and that regulation of VCAM-1 expression is mediated via nuclear factor-kappaB (NF-kappaB), we hypothesized that celiprolol activates phosphorylation of eNOS through the PI3K-Akt signaling pathway; that celiprolol modulates VCAM-1 expression, which is associated with inhibiting NF-kappaB phosphorylation; and that celiprolol suppresses NAD(P)H oxidase p22phox, p47phox, gp91phox, and nox1 expression in the left ventricle of deoxycorticosterone acetate (DOCA)-salt hypertensive rats. eNOS and Akt phosphorylation upregulated by celiprolol alone were suppressed by treatment with celiprolol plus wortmannin. Increased expression of VCAM-1, p22phox, p47phox, gp91phox, nox1, activated p65 NF-kappaB, c-Src, p44/p42 extracellular signal-regulated kinases, and their downstream effector p90 ribosomal S6 kinase phosphorylation in DOCA rats was inhibited by celiprolol. Celiprolol administration resulted in a significant improvement in cardiovascular remodeling and suppression of transforming growth factor-beta1 gene expression. In conclusion, celiprolol suppresses VCAM-1 expression because of inhibition of oxidative stress, NF-kappaB, and signal transduction, while increasing eNOS via stimulation of the PI3K-Akt signaling pathway and improving cardiovascular remodeling.  相似文献   
93.
Although native cholera toxin (CT) is an extremely effective adjuvant, its toxicity prevents its use in humans. We report here that apple polyphenol extract (APE), obtained from unripe apples, reduces CT-induced morphological changes and cAMP accumulation. Based upon this finding, we have attempted to design a novel, effective and safe mucosal vaccine by using CT with several dosages of APE as nasal adjuvants. Mice nasally immunized with OVA plus CT and an optimal dosage of APE showed significantly reduced levels of inflammatory responses as well as total and OVA-specific IgE antibodies when compared with mice given without APE. However, levels of both mucosal and systemic OVA-specific antibody responses were maintained. Further, APE significantly down-regulated accumulation of CT in the olfactory nerves and epithelium. In summary, an optimal dosage of APE would take full advantage of mucosal adjuvanticity of native CT without any toxicity for application in humans.  相似文献   
94.
Rice-expressed cholera toxin B (CTB) subunit is a cold-chain-free oral vaccine that effectively induces enterotoxin-neutralising immunity. We created another rice-based vaccine, MucoRice, expressing nontoxic double-mutant cholera toxin (dmCT) with CTA and CTB subunits. Western-blot analysis suggested that MucoRice-dmCT had the shape of a multicomponent vaccine. Oral administration of MucoRice-dmCT induced CTB- but not CTA-specific serum IgG and mucosal IgA antibodies, generating protective immunity against cholera toxin without inducing rice-protein-specific antibody responses. The potency of MucoRice-dmCT was equal to that of MucoRice-CTB vaccine. MucoRice has the potential to be used as a safe multicomponent vaccine expression system.  相似文献   
95.
We have recently demonstrated that the low-energy extracorporeal cardiac shock wave (SW) therapy improves myocardial perfusion and cardiac function in a porcine model of chronic myocardial ischemia and also ameliorates myocardial ischemia in patients with severe coronary artery disease. The present study was designed to examine whether our SW therapy also is effective to ameliorate hindlimb ischemia in rabbits. Hindlimb ischemia was made by surgical excision of the entire unilateral rabbit femoral artery. One week after the operation, we performed the SW (n = 9) or sham-therapy (n = 9) to the ischemic region 3 times a week for 3 weeks. Three weeks after the SW therapy, the development of collateral arteries, the flow ratio of the ischemic/non-ischemic common iliac arteries, the blood pressure ratio of the ischemic/non-ischemic hindlimb, and the capillary density in the ischemic muscles were all significantly increased in the SW group compared with the control group, indicating that the SW therapy induced therapeutic angiogenesis. Importantly, no adverse effect, such as muscle damage, hemorrhage, or thrombosis, was noted with the therapy. Finally, we examined the role of endothelial nitric oxide synthesis (eNOS) and vascular endothelial growth factor (VEGF) in the mechanisms of SW-induced angiogenesis on day 28. The expression levels of eNOS and VEGF proteins in ischemic hindlimb muscles tended to be increased in the SW group compared with the control group. These results suggest that our low-energy SW therapy also is effective and safe for the treatment of peripheral artery disease.  相似文献   
96.
OBJECTIVE: We have recently demonstrated that low-energy extracorporeal shock wave therapy improves chronic myocardial ischemia in pigs and humans. In this study, we examined whether our shock wave therapy is also effective at improving left ventricular remodeling after acute myocardial infarction in pigs. METHODS: Acute myocardial infarction was created by surgically excising the proximal segment of the left circumflex coronary artery (n=20). In the early treatment protocol, the shock wave therapy was started 3 days after acute myocardial infarction, whereas in the late treatment protocol, the therapy was started 4 weeks after acute myocardial infarction (n=5 each). The remaining animals were treated in the same manner, but without the shock wave treatment in each protocol (n=5 each). RESULTS: In the early treatment protocol, left ventricular ejection fraction was higher (42+/-1 vs. 32+/-1%, P<0.001) and left ventricular end-diastolic volume was smaller (95+/-1 vs. 99+/-2 ml, P<0.05) in the shock wave group compared with the control group. Furthermore, wall thickening fraction (32+/-1 vs. 28+/-1%, P<0.01), regional myocardial blood flow (1.7+/-0.2 vs. 1.0+/-0.1 ml/min/g, P<0.01), and number of capillaries in the border zone (1348+/-15 vs. 938+/-34 mm2, P<0.0001) were all significantly improved in the shock wave group compared with the control group. By contrast, in the late treatment group, no such beneficial effects of the shock wave therapy were noted. CONCLUSION: These results suggest that our extracorporeal cardiac shock wave therapy is also an effective and noninvasive therapy for improving left ventricular remodeling after acute myocardial infarction when started in the early phase of the disorder.  相似文献   
97.
Evidence that some types of epilepsies show strong genetic predisposition has been well documented. AP3M2 is considered to be an epileptogenic gene because AP3M2 knockout mice exhibit symptoms of spontaneous epileptic seizures. In order to investigate whether the AP3M2 gene causes susceptibility to epilepsy, we performed mutation screening of the genomic DNA of 190 patients with six epilepsy types; this screening involved all the 9 exons and the relevant exon-intron boundaries of AP3M2. Although neither missense nor nonsense mutations were detected, we identified 21 sequence variations, of which 16 variations were novel. Of the 21 variations, 11 were detected in 5' and 3' UTRs, while the remaining variations were detected in introns. Although the present study failed to identify the possible AP3M2 mutations that may cause epilepsy, our results suggest that some AP3M2 mutations still remain candidates for unmapped disorders including epilepsy, febrile seizure, and other neuronal developmental disorders associated with functional abnormalities of GABAergic transmission.  相似文献   
98.
99.
A T cell receptor transgenic mouse line reactive to a microbiota flagellin, CBir1, was used to define mechanisms of host microbiota homeostasis. Intestinal IgA, but not serum IgA, was found to block mucosal flagellin uptake and systemic T cell activation in mice. Depletion of CD4+CD25+ Tregs decreased IgA+ B cells, total IgA, and CBir1-specific IgA in gut within days. Repletion of T cell-deficient mice with either CD4+CD25+ or CD4+foxp3+ Tregs restored intestinal IgA to a much greater extent than their reciprocal CD4+ subsets, indicating that Tregs are the major helper cells for IgA responses to microbiota antigens such as flagellin. We propose that the major role of this coordinated Treg-IgA response is to maintain commensalism with the microbiota.  相似文献   
100.
Approximately one-half of the cases of Budd-Chiari syndrome (BCS) are caused by bcr/abl negative chronic myeloproliferative disorders (CMPDs). Furthermore, a mutation in the Janus kinase protein (JAK2-V617F) is detected in half of the patients with BCS. However, whether the JAK2 mutation is the primary event leading to CMPDs and BCS is controversial. We present a report concerning a young woman who suffered from BCS prior to the onset of CMPDs. Analysis of X-chromosome inactivation patterns in this patient, using the human androgen receptor gene demonstrated monoclonal haematopoiesis in her granulocytes. In contrast, she had a low burden of a JAK2-V617F mutation positive clone among granulocyte populations. These results suggest that the JAK2-V617F mutation occurs after the onset of monoclonal haematopoiesis; thus the V617F mutation of JAK2 may not be the primary event in the induction of BCS.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号