全文获取类型
收费全文 | 3478篇 |
免费 | 228篇 |
国内免费 | 15篇 |
专业分类
耳鼻咽喉 | 21篇 |
儿科学 | 127篇 |
妇产科学 | 113篇 |
基础医学 | 535篇 |
口腔科学 | 39篇 |
临床医学 | 278篇 |
内科学 | 798篇 |
皮肤病学 | 81篇 |
神经病学 | 425篇 |
特种医学 | 165篇 |
外科学 | 343篇 |
综合类 | 13篇 |
一般理论 | 1篇 |
预防医学 | 212篇 |
眼科学 | 25篇 |
药学 | 231篇 |
中国医学 | 5篇 |
肿瘤学 | 309篇 |
出版年
2024年 | 5篇 |
2023年 | 44篇 |
2022年 | 113篇 |
2021年 | 150篇 |
2020年 | 103篇 |
2019年 | 126篇 |
2018年 | 115篇 |
2017年 | 100篇 |
2016年 | 109篇 |
2015年 | 125篇 |
2014年 | 174篇 |
2013年 | 205篇 |
2012年 | 312篇 |
2011年 | 304篇 |
2010年 | 156篇 |
2009年 | 148篇 |
2008年 | 262篇 |
2007年 | 215篇 |
2006年 | 177篇 |
2005年 | 193篇 |
2004年 | 142篇 |
2003年 | 121篇 |
2002年 | 86篇 |
2001年 | 19篇 |
2000年 | 23篇 |
1999年 | 23篇 |
1998年 | 19篇 |
1997年 | 17篇 |
1996年 | 17篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 9篇 |
1992年 | 14篇 |
1991年 | 14篇 |
1990年 | 12篇 |
1988年 | 9篇 |
1987年 | 4篇 |
1986年 | 12篇 |
1985年 | 6篇 |
1984年 | 10篇 |
1983年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1970年 | 3篇 |
1967年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有3721条查询结果,搜索用时 0 毫秒
11.
Vitamin E affects cell death in adult rat dentate gyrus 总被引:1,自引:0,他引:1
Ferri P Cecchini T Ciaroni S Ambrogini P Cuppini R Santi S Benedetti S Pagliarani S Del Grande P Papa S 《Journal of neurocytology》2003,32(9):1155-1164
We have previously reported the presence of dying cells in the granule cell layer (GCL) of adult rat dentate gyrus (DG), where neurogenesis occurs. In particular, we found that cell death in the GCL increased in vitamin E deficiency and decreased in vitamin E supplementation. These findings were regarded as related to changes in neurogenesis rate, which in turn was influenced by vitamin E availability; a neuroprotective effect of vitamin E on cell death was also proposed. In order to verify this latter hypothesis, we have studied cell death in all layers of DG in vitamin E-deficient and vitamin E-supplemented rats and in control rats at different ages, using TUNEL and nick translation techniques. The phenotype of TUNEL-positive cells was characterized and the existence of dying BrdU-positive cells was investigated. Dying cells with neuronal phenotype were observed throughout the DG in all experimental groups. The number of TUNEL-positive cells decreased from juvenile to adult age. A higher number of TUNEL-positive cells in vitamin E-deficient rats and a lower number in vitamin E-supplemented rats, with respect to age-matched controls, were found; moreover, in these groups, TUNEL-positive cells had a different percentage distribution in the different layers of the DG. Our results confirm the occurrence of cell death in DG, demonstrate that cell death affects neuronal cells and support the hypothesis that the effect of vitamin E on cell death is not related to neurogenesis. 相似文献
12.
13.
Improved survival of ischemic cutaneous and musculocutaneous flaps after vascular endothelial growth factor gene transfer using adeno-associated virus vectors 下载免费PDF全文
Zacchigna S Papa G Antonini A Novati F Moimas S Carrer A Arsic N Zentilin L Visintini V Pascone M Giacca M 《The American journal of pathology》2005,167(4):981-991
A major challenge in reconstructive surgery is flap ischemia, which might benefit from induction of therapeutic angiogenesis. Here we demonstrate the effect of an adeno-associated virus (AAV) vector delivering vascular endothelial growth factor (VEGF)165 in two widely recognized in vivo flap models. For the epigastric flap model, animals were injected subcutaneously with 1.5 x 10(11) particles of AAV-VEGF at day 0, 7, or 14 before flap dissection. In the transverse rectus abdominis musculocutaneous flap model, AAV-VEGF was injected intramuscularly. The delivery of AAV-VEGF significantly improved flap survival in both models, reducing necrosis in all treatment groups compared to controls. The most notable results were obtained by administering the vector 14 days before flap dissection. In the transverse rectus abdominis musculocutaneous flap model, AAV-VEGF reduced the necrotic area by >50% at 1 week after surgery, with a highly significant improvement in the healing process throughout the following 2 weeks. The therapeutic effect of AAV-VEGF on flap survival was confirmed by histological evidence of neoangiogenesis in the formation of large numbers of CD31-positive capillaries and alpha-smooth muscle actin-positive arteriolae, particularly evident at the border between viable and necrotic tissue. These results underscore the efficacy of VEGF-induced neovascularization for the prevention of tissue ischemia and the improvement of flap survival in reconstructive surgery. 相似文献
14.
15.
Ciaroni S Cecchini T Ferri P Cuppini R Ambrogini P Santi S Benedetti S Del Grande P Papa S 《Neuroscience research》2002,44(4):369-377
The adult hippocampal neurogenesis is affected by vitamin E deficiency. In the present investigation we examined if neural precursor proliferation, newborn cell survival or both are altered by vitamin E deficiency. 5-Bromo-2'-deoxyuridine (BrdU) was employed as a marker of proliferating cells. BrdU-labelled cells were revealed 1 and 30 days after BrdU administration in order to evaluate proliferation and newborn cell survival, respectively. Cell proliferation decreased in controls from juvenile to adult age, and the decrease was lesser in vitamin E deficiency. Thus we found a higher number of proliferating cells in vitamin E-deficient rats than in age-matched controls at 5 months of age. Comparing the number of BrdU-positive cells between 1 and 30 days after the last BrdU injection revealed a remarkable decrease in all groups; this is the greatest in vitamin E-deficient rats and the lowest in control rats. Consistently cell death in the dentate gyrus, assessed by TUNEL technique, was found to decrease from 1 to 5 months of age, but at 5 months it was significantly higher in vitamin E-deficient rats than in age-matched controls. These data show that vitamin E deficiency enhances neural precursor proliferation and cell death during adult neurogenesis. 相似文献
16.
Simona Di Terlizzi Elisabetta Zino Benedetta Mazzi Chiara Magnani Cristina Tresoldi Serena Kimi Perna Marco Bregni Silvano Rossini Fabio Ciceri Claudio Bordignon Chiara Bonini Katharina Fleischhauer 《Biology of blood and marrow transplantation》2006,12(1):95-101
Minor histocompatibility antigens (mHags) HA-1 and HA-2 are encoded by biallelic loci, with immunogenic variants, HA-1H and HA-2V, which induce strong HLA-A2-restricted alloreactive T-cell responses, and nonimmunogenic counterparts, HA-1R and HA-2M, which represent functional null alleles that are poorly presented by HLA class I molecules. HA-1 and HA-2 are potential targets of selective graft-versus-leukemia and graft-versus-tumor reactivity after allogeneic hematopoietic stem cell transplantation (HSCT); however, these applications are restricted to a limited number of patients. Here, we show that a far more frequent application of HA-1 and HA-2 disparity relies on their use as markers for the state of host chimerism after allogeneic HSCT. We have determined allelic frequencies of 29.3% and 70.7% for HA-1H and HA-1R, respectively, and of 83.7% and 16.3% for HA-2V and HA-2M, respectively, in >200 healthy individuals from northern Italy. Similar frequencies were observed in nearly 100 patients affected by hematologic malignancies or solid tumors, thus showing that HA-1 and HA-2 variability are not associated with the presence of cancer. On the basis of these data, we predict that HA-1 and HA-2 can be used in 32.8% and 23.5% of Italian transplant patients, respectively, as markers for the state of host chimerism, whereas exploitation of disparity for these mHags for targeted immunotherapy will be possible in 10.7% and 1.1% of Italian patients, respectively. Retrospective HA-2 typing of bone marrow aspirates obtained from a patient during complete remission or recurrence of acute myeloid leukemia after haploidentical HSCT showed the feasibility of using HA-2 as a surrogate marker for disease monitoring. Because of an apparent north-south gradient for HA-1 allelic frequencies, with higher frequencies for the HA-1H variant reported in white populations from Southern Europe as compared with Northern Europe and North America, the diagnostic applicability of HA-1 disparity will be slightly more frequent in transplant patients from the north. Taken together, our data show that determination of HA-1 and HA-2 variability can be an important parameter for the selection of allogeneic stem cell donors, in particular for patients affected by hematologic malignancies without a tumor-specific molecular marker. 相似文献
17.
Reciprocal stimulation of gammadelta T cells and dendritic cells during the anti-mycobacterial immune response 总被引:2,自引:0,他引:2
Dieli F Caccamo N Meraviglia S Ivanyi J Sireci G Bonanno CT Ferlazzo V La Mendola C Salerno A 《European journal of immunology》2004,34(11):3227-3235
Gammadelta T cells and dendritic cells (DC) are two distinct cell types of innate immunity that participate in early phases of immune response against Mycobacterium tuberculosis infection. Here we show that a close functional relationship exists between these cell populations. Using an in vitro coculture system, Vgamma1 T cells from Tcrb(-/- )mice were found to be activated by DC infected in vitro with BCG, as indicated by the elevated CD69 expression, IFN-gamma secretion and cytotoxic activity. This activation process was due to a non-cognate mechanism since it required neither cell to cell contact nor interaction between the TCR and a specific antigen, but was mediated by DC-derived IL-12. Reciprocally, Vgamma1 T cells provided a key cytokine, IFN-gamma, which increased IL-12 production by BCG-infected DC. Moreover, exposure of BCG-infected DC to Vgamma1 T cells conditioned the former to prime a significantly stronger anti-mycobacterial CD8 T cell response. Consequently, stimulation of gammadelta T cells and their non-cognate interaction with DC could be applied as an immune adjuvant strategy to optimize vaccine-induced CD8 T cell immunity. 相似文献
18.
19.
Olaug K. Rødningen Oddveig Røshy Serena Tonstad Leiv Ose Kåre Berg Trond P. Leren 《Clinical genetics》1992,42(6):288-295
Haplotype analysis of the low density lipoprotein receptor (LDLR) gene was performed in Norwegian subjects heterozygous for familial hypercholesterolemia (FH). Southern blot analysis of genomic DNA, using an exon 18 specific probe and the restriction enzyme NcoI, showed that two out of 57 unrelated FH subjects had an abnormal 3.6 kb band. Further analyses revealed that this abnormal band was due to a 9.6 kb deletion that included exons 16 and 17. The 5' deletion breakpoint was after 245 bp of intron 15, and the 3' deletion breakpoint was in exon 18 after nucleotide 3390 of cDNA. Thus, both the membrane-spanning and cytoplasmatic domains of the receptor had been deleted. A polymerase chain reaction (PCR) method was developed to identify this deletion among other Norwegian FH subjects. As a result of this screening one additional subject was found out of 124 subjects screened. Thus, three out of 181 (1.7%) unrelated Norwegian FH subject possessed this deletion. The deletion was found on the same haplotype in the three unrelated subjects, suggesting a common mutagenic event. The deletion is identical to a deletion (FH-Helsinki) that is very common among Finnish FH subjects. However, it is not yet known whether the mutations evolved separately in the two countries. 相似文献
20.