全文获取类型
收费全文 | 1812篇 |
免费 | 118篇 |
专业分类
1930篇 |
出版年
2023年 | 8篇 |
2022年 | 13篇 |
2021年 | 36篇 |
2020年 | 15篇 |
2019年 | 42篇 |
2018年 | 44篇 |
2017年 | 27篇 |
2016年 | 42篇 |
2015年 | 81篇 |
2014年 | 110篇 |
2013年 | 130篇 |
2012年 | 135篇 |
2011年 | 151篇 |
2010年 | 92篇 |
2009年 | 87篇 |
2008年 | 119篇 |
2007年 | 113篇 |
2006年 | 107篇 |
2005年 | 109篇 |
2004年 | 106篇 |
2003年 | 79篇 |
2002年 | 68篇 |
2001年 | 14篇 |
2000年 | 10篇 |
1999年 | 14篇 |
1998年 | 17篇 |
1997年 | 12篇 |
1996年 | 10篇 |
1995年 | 16篇 |
1994年 | 14篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 11篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1972年 | 2篇 |
1970年 | 2篇 |
排序方式: 共有1930条查询结果,搜索用时 0 毫秒
11.
Gabriella Juhasz Xenia Gonda Gabor Hullam Nora Eszlari David Kovacs Judit Lazary Dorottya Pap Peter Petschner Rebecca Elliott John Francis William Deakin Ian Muir Anderson Peter Antal Klaus-Peter Lesch Gyorgy Bagdy 《PloS one》2015,10(3)
Background
Although 5-HTTLPR has been shown to influence the risk of life stress-induced depression in the majority of studies, others have produced contradictory results, possibly due to weak effects and/or sample heterogeneity.Methods
In the present study we investigated how age, type and intensity of life-stressors modulate the effect of 5-HTTLPR on depression and anxiety in a European population cohort of over 2300 subjects. Recent negative life events (RLE), childhood adversity (CHA), lifetime depression, Brief Symptoms Inventory (BSI) depression and anxiety scores were determined in each subject. Besides traditional statistical analysis we calculated Bayesian effect strength and relevance of 5-HTTLPR genotypes in specified models.Results
The short (s) low expressing allele showed association with increased risk of depression related phenotypes, but all nominally significant effects would turn to non-significant after correction for multiple testing in the traditional analysis. Bayesian effect strength and relevance analysis, however, confirmed the role of 5-HTTLPR. Regarding current (BSI) and lifetime depression 5-HTTLPR-by-RLE interactions were confirmed. Main effect, with other words direct association, was supported with BSI anxiety. With more frequent RLE the prevalence or symptoms of depression increased in ss carriers. Although CHA failed to show an interaction with 5-HTTLPR, in young subjects CHA sensitized towards the depression promoting effect of even mild RLE. Furthermore, the direct association of anxiety with the s allele was driven by young (≤30) individuals.Limitations
Our study is cross-sectional and applies self-report questionnaires.Conclusions
Albeit 5-HTTLPR has only weak/moderate effects, the s allele is directly associated with anxiety and modulates development of depression in homogeneous subgroups. 相似文献12.
Gabriella Eliason Samy M Abdel-Halim Karin Piehl-Aulin Fawzi Kadi 《Respiratory research》2010,11(1):97
Background
It is hypothesized that decreased capillarization of limb skeletal muscle is implicated in the decreased exercise tolerance in COPD patients. We have recently demonstrated decreased number of capillaries per muscle fibre (CAF) but no changes in CAF in relation to fibre area (CAFA), which is based on the diffusion distance between the capillary and muscle fibre. The aim of the current study is to investigate the muscle-to-capillary interface which is an important factor involved in oxygen supply to the muscle that has previously been suggested to be a more sensitive marker for changes in the capillary bed compared to CAF and CAFA.Methods
23 COPD patients and 12 age-matched healthy subjects participated in the study. Muscle-to-capillary interface was assessed in muscle biopsies from the tibialis anterior muscle using the following parameters:1) The capillary-to-fibre ratio (C:Fi) which is defined as the sum of the fractional contributions of all capillary contacts around the fibre2) The ratio between C:Fi and the fibre perimeter (CFPE-index)3) The ratio between length of capillary and fibre perimeter (LC/PF) which is also referred to as the index of tortuosity.Exercise capacity was determined using the 6-min walking test.Results
A positive correlation was found between CFPE-index and ascending disease severity with CFPE-index for type I fibres being significantly lower in patients with moderate and severe COPD. Furthermore, a positive correlation was observed between exercise capacity and CFPE-index for both type I and type IIa fibres.Conclusion
It can be concluded that the muscle-to-capillary interface is disturbed in the tibialis anterior muscle in patients with COPD and that interface is strongly correlated to increased disease severity and to decreased exercise capacity in this patient group. 相似文献13.
Coccetti P Zinzalla V Tedeschi G Russo GL Fantinato S Marin O Pinna LA Vanoni M Alberghina L 《Biochemical and biophysical research communications》2006,346(3):786-793
We have previously identified Ser201 of Sic1, a yeast cyclin-dependent kinase inhibitor, as an in vitro target of protein kinase CK2. Here we present new evidence, by using specific anti-P-Ser201 antibodies and 2-D gel electrophoresis coupled to MALDI mass spectrometry analysis, that Sic1 is phosphorylated in vivo on Ser201 shortly after its de novo synthesis, during late anaphase in glucose-grown cells. This phosphorylation is also detected in Sic1 immunopurified from G1 cells. In agreement with these data we also show that the catalytic alpha' subunit of CK2, whose function is required for cell cycle progression, is detected in Sic1 immunopurified complexes, and that phosphorylation on Ser201 is reduced after CK2 inactivation at the non-permissive temperature in a cka1delta cka2(ts) yeast strain. These data strongly support the notion that CK2 phosphorylates Sic1 in vivo. 相似文献
14.
HOTAIR role in melanoma progression and its identification in the blood of patients with advanced disease 下载免费PDF全文
15.
Crisan M Yap S Casteilla L Chen CW Corselli M Park TS Andriolo G Sun B Zheng B Zhang L Norotte C Teng PN Traas J Schugar R Deasy BM Badylak S Buhring HJ Giacobino JP Lazzari L Huard J Péault B 《Cell Stem Cell》2008,3(3):301-313
Mesenchymal stem cells (MSCs), the archetypal multipotent progenitor cells derived in cultures of developed organs, are of unknown identity and native distribution. We have prospectively identified perivascular cells, principally pericytes, in multiple human organs including skeletal muscle, pancreas, adipose tissue, and placenta, on CD146, NG2, and PDGF-Rbeta expression and absence of hematopoietic, endothelial, and myogenic cell markers. Perivascular cells purified from skeletal muscle or nonmuscle tissues were myogenic in culture and in vivo. Irrespective of their tissue origin, long-term cultured perivascular cells retained myogenicity; exhibited at the clonal level osteogenic, chondrogenic, and adipogenic potentials; expressed MSC markers; and migrated in a culture model of chemotaxis. Expression of MSC markers was also detected at the surface of native, noncultured perivascular cells. Thus, blood vessel walls harbor a reserve of progenitor cells that may be integral to the origin of the elusive MSCs and other related adult stem cells. 相似文献
16.
Pauline Scherdel Jean-Fran?ois Salaün Marie-No?lle Robberecht-Riquet Laura Reali Gabriella Páll Elke J?ger-Roman Manuel Praena Crespo Marilena Moretto Margareta Seher-Zupan?i? Sigurlaug Agustsson the European Confederation of Primary Care Paediatricians research group Martin Chalumeau 《PloS one》2013,8(8)
Objective
We aimed to study current practices in growth monitoring by European primary care paediatricians and to explore their perceived needs in this field.Methods
We developed a cross-sectional, anonymous on-line survey and contacted primary care paediatricians listed in national directories in the 18 European countries with a confederation of primary care paediatricians. Paediatricians participated in the survey between April and September 2011.Results
Of the 1,198 paediatricians from 11 European countries (response rate 13%) who participated, 29% used the 2006 World Health Organization Multicentre Growth Reference Study growth charts, 69% used national growth charts; 61% used software to draw growth charts and 79% did not use a formal algorithm to detect abnormal growth on growth charts. Among the 21% of paediatricians who used algorithms, many used non-algorithmic simple thresholds for height and weight and none used the algorithms published in the international literature. In all, 69% of paediatricians declared that a validated algorithm to monitor growth would be useful in daily practice. We found important between-country variations.Conclusion
The varied growth-monitoring practices declared by primary care paediatricians reveals the need for standardization and evidence-based algorithms to define abnormal growth and the development of software that would use such algorithms. 相似文献17.
Teresa Mattiello Gabriella Fiore Euan R. Brown Marco d'Ischia Anna Palumbo 《The Journal of biological chemistry》2010,285(31):24154-24163
Chromatophore organs are complex and unique structures responsible for the variety of body coloration patterns used by cephalopods to communicate and camouflage. They are formed by a pigment-containing cytoelastic sacculus, surrounded by muscle fibers directly innervated from the brain. Muscle contraction and relaxation are responsible for expansion and retraction of the pigment-containing cell. Their functioning depends on glutamate and Phe-Met-Arg-Phe-NH2-related peptides, which induce fast and slow cell expansion, respectively, and 5-hydroxytryptamine, which induces retraction. Apart from these three substances and acetylcholine, which acts presynaptically, no other neuroactive compounds have so far been found to be involved in the neuroregulation of chromatophore physiology, and the detailed signaling mechanisms are still little understood. Herein, we disclose the role of nitric oxide (NO) as mediator in one of the signaling pathways by which glutamate activates body patterning. NO and nitric-oxide synthase have been detected in pigment and muscle fibers of embryo, juvenile, and adult chromatophore organs from Sepia officinalis. NO-mediated Sepia chromatophore expansion operates at slower rate than glutamate and involves cGMP, cyclic ADP-ribose, and ryanodine receptor activation. These results demonstrate for the first time that NO is an important messenger in the long term maintenance of the body coloration patterns in Sepia. 相似文献
18.
Rawson PM Molette C Videtta M Altieri L Franceschini D Donato T Finocchi L Propato A Paroli M Meloni F Mastroianni CM d'Ettorre G Sidney J Sette A Barnaba V 《Nature medicine》2007,13(12):1431-1439
We found that the proteome of apoptotic T cells includes prominent fragments of cellular proteins generated by caspases and that a high proportion of distinct T cell epitopes in these fragments is recognized by CD8+ T cells during HIV infection. The frequencies of effector CD8+ T cells that are specific for apoptosis-dependent epitopes correlate with the frequency of circulating apoptotic CD4+ T cells in HIV-1-infected individuals. We propose that these self-reactive effector CD8+ T cells may contribute to the systemic immune activation during chronic HIV infection. The caspase-dependent cleavage of proteins associated with apoptotic cells has a key role in the induction of self-reactive CD8+ T cell responses, as the caspase-cleaved fragments are efficiently targeted to the processing machinery and are cross-presented by dendritic cells. These findings demonstrate a previously undescribed role for caspases in immunopathology. 相似文献
19.
20.
Tripodi SA Del Vecchio MT Supuran CT Scozzafava A Gabrielli MG Pastorekova S Rossie R Fasolis G Puccetti L 《Journal of enzyme inhibition and medicinal chemistry》2004,19(3):287-291
Clear renal cell carcinomas (RCC) frequently express carbonic anydrase IX (CA IX) because of non-functional mutation of von Hippel Lindau (VHL) tumor suppressor gene. CA IX is a tumor-associated transmembrane antigen, which catalyzes the extracellular, reversible hydration of carbon dioxide to bicarbonate and proton and thereby contributes to acidification of extracellular milieu. Extracellular acidic pH facilitates tumor growth and progression. CA IX expression is upregulated by Hypoxia Inducible Factor-1 (HIF-1), which is negatively controlled by oxygen via wild type VHL protein and is also regulated by the cell redox state. We investigated the immunohistochemical pattern of distribution of CA IX in a small series (14 cases) of RCCs. CA IX expression was matched with the redox state of RCC, stratifying our series in relation to clinical and histopathological parameters, such as Fuhrman grade, staging, proliferation markers expression, and particularly, the presence of necrosis. Our results show for the first time the existence of a perivascular pattern of CA IX distribution in RCC. We also found a significant relationship between CA IX expression and the presence of necrosis. Tumors with higher CA IX expression exhibited higher degree of necrosis (p < 0.05). Notably, an almost significant relationship between the redox state and CA IX expression was detected in RCC patients with 5 years disease-free survival, most of them showing organ-confined disease. Tumors with lower redox state showed an algebraically higher degree of CA IX expression. On the contrary, tumors with higher redox state exhibited an algebraically lower CA IX expression (p = 0.057). The observed relationship of CA IX expression and necrosis suggests a role for CA IX in RCC. Further investigations are necessary to further establish the role of the redox state in regulation of CA IX expression in RCC. 相似文献