全文获取类型
收费全文 | 549篇 |
免费 | 59篇 |
出版年
2022年 | 7篇 |
2021年 | 18篇 |
2020年 | 7篇 |
2019年 | 7篇 |
2018年 | 14篇 |
2016年 | 9篇 |
2015年 | 21篇 |
2014年 | 21篇 |
2013年 | 25篇 |
2012年 | 48篇 |
2011年 | 29篇 |
2010年 | 11篇 |
2009年 | 21篇 |
2008年 | 16篇 |
2007年 | 11篇 |
2006年 | 20篇 |
2005年 | 11篇 |
2004年 | 11篇 |
2003年 | 12篇 |
2002年 | 15篇 |
2001年 | 12篇 |
2000年 | 8篇 |
1999年 | 10篇 |
1998年 | 11篇 |
1997年 | 5篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1993年 | 9篇 |
1992年 | 9篇 |
1991年 | 12篇 |
1990年 | 9篇 |
1989年 | 11篇 |
1988年 | 5篇 |
1987年 | 14篇 |
1985年 | 11篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1974年 | 11篇 |
1973年 | 4篇 |
1972年 | 4篇 |
1971年 | 10篇 |
1970年 | 6篇 |
1969年 | 5篇 |
1968年 | 4篇 |
1966年 | 9篇 |
1965年 | 4篇 |
排序方式: 共有608条查询结果,搜索用时 15 毫秒
111.
Jan-Peter Sowa ?zgür Atmaca Alisan Kahraman Martin Schlattjan Marion Lindner Svenja Sydor Norbert Scherbaum Karoline Lackner Guido Gerken Dominik Heider Gavin E. Arteel Yesim Erim Ali Canbay 《PloS one》2014,9(7)
Background & Objective
Currently, a major clinical challenge is to distinguish between chronic liver disease caused by metabolic syndrome (non-alcoholic fatty liver disease, NAFLD) from that caused by long term or excessive alcohol consumption (ALD). The etiology of severe liver disease affects treatment options and priorities for liver transplantation and organ allocation. Thus we compared physiologically similar NAFLD and ALD patients to detect biochemical differences for improved separation of these mechanistically overlapping etiologies.Methods
In a cohort of 31 NAFLD patients with BMI below 30 and a cohort of ALD patient with (ALDC n = 51) or without cirrhosis (ALDNC n = 51) serum transaminases, cell death markers and (adipo-)cytokines were assessed. Groups were compared with One-way ANOVA and Tukey''s correction. Predictive models were built by machine learning techniques.Results
NAFLD, ALDNC or ALDC patients did not differ in demographic parameters. The ratio of alanine aminotransferase/aspartate aminotransferase - common serum parameters for liver damage - was significantly higher in the NAFLD group compared to both ALD groups (each p<0.0001). Adiponectin and tumor necrosis factor(TNF)-alpha were significantly lower in NAFLD than in ALDNC (p<0.05) or ALDC patients (p<0.0001). Significantly higher serum concentrations of cell death markers, hyaluronic acid, adiponectin, and TNF-alpha (each p<0.0001) were found in ALDC compared to ALDNC. Using machine learning techniques we were able to discern NAFLD and ALDNC (up to an AUC of 0.9118±0.0056) or ALDC and ALDNC (up to an AUC of 0.9846±0.0018), respectively.Conclusions
Machine learning techniques relying on ALT/AST ratio, adipokines and cytokines distinguish NAFLD and ALD. In addition, severity of ALD may be non-invasively diagnosed via serum cytokine concentrations. 相似文献112.
113.
Moein Khalighi Guilhem Sommeria-Klein Didier Gonze Karoline Faust Leo Lahti 《PLoS computational biology》2022,18(6)
Ecological memory refers to the influence of past events on the response of an ecosystem to exogenous or endogenous changes. Memory has been widely recognized as a key contributor to the dynamics of ecosystems and other complex systems, yet quantitative community models often ignore memory and its implications.Recent modeling studies have shown how interactions between community members can lead to the emergence of resilience and multistability under environmental perturbations. We demonstrate how memory can be introduced in such models using the framework of fractional calculus. We study how the dynamics of a well-characterized interaction model is affected by gradual increases in ecological memory under varying initial conditions, perturbations, and stochasticity.Our results highlight the implications of memory on several key aspects of community dynamics. In general, memory introduces inertia into the dynamics. This favors species coexistence under perturbation, enhances system resistance to state shifts, mitigates hysteresis, and can affect system resilience both ways depending on the time scale considered. Memory also promotes long transient dynamics, such as long-standing oscillations and delayed regime shifts, and contributes to the emergence and persistence of alternative stable states. Our study highlights the fundamental role of memory in communities, and provides quantitative tools to introduce it in ecological models and analyse its impact under varying conditions. 相似文献
114.
Davit Bzhalava Hanna Johansson Johanna Ekstr?m Helena Faust Birgitta M?ller Carina Eklund Peter Nordin Bo Stenquist John Paoli Bengt Persson Ola Forslund Joakim Dillner 《PloS one》2013,8(6)
To assess presence of virus DNA in skin lesions, swab samples from 82 squamous cell carcinomas of the skin (SCCs), 60 actinic keratoses (AKs), paraffin-embedded biopsies from 28 SCCs and 72 kerathoacanthomas (KAs) and fresh-frozen biopsies from 92 KAs, 85 SCCs and 92 AKs were analyzed by high throughput sequencing (HTS) using 454 or Ion Torrent technology. We found total of 4,284 viral reads, out of which 4,168 were Human Papillomavirus (HPV)-related, belonging to 15 known (HPV8, HPV12, HPV20, HPV36, HPV38, HPV45, HPV57, HPV59, HPV104, HPV105, HPV107, HPV109, HPV124, HPV138, HPV147), four previously described putative (HPV 915 F 06 007 FD1, FA73, FA101, SE42) and two putatively new HPV types (SE46, SE47). SE42 was cloned, sequenced, designated as HPV155 and found to have 76% similarity to the most closely related known HPV type. In conclusion, an unbiased approach for viral DNA detection in skin tumors has found that, although some new putative HPVs were found, known HPV types constituted most of the viral DNA. 相似文献
115.
116.
117.
(+)-Nicotianamine and its naturally occurring antipode exhibited the same biological activity with regard to chlorophyll formation of chlorotic leaflets of the mutant chloronerva. It is therefore concluded that nicotianamine does not exert its functions by a stereospecific binding to a macromolecular surface. 相似文献
118.
Claudia P?sel Karoline M?ller Wenke Fr?hlich Isabell Schulz Johannes Boltze Daniel-Christoph Wagner 《PloS one》2012,7(12)
Bone marrow mononuclear cells (BMNCs) are widely used in regenerative medicine, but recent data suggests that the isolation of BMNCs by commonly used Ficoll-Paque density gradient centrifugation (DGC) causes significant cell loss and influences graft function. The objective of this study was to determine in an animal study whether and how Ficoll-Paque DGC affects the yield and composition of BMNCs compared to alternative isolation methods such as adjusted Percoll DGC or immunomagnetic separation of polymorphonuclear cells (PMNs). Each isolation procedure was confounded by a significant loss of BMNCs that was maximal after Ficoll-Paque DGC, moderate after adjusted Percoll DGC and least after immunomagnetic PMN depletion (25.6±5.8%, 51.5±2.3 and 72.3±6.7% recovery of total BMNCs in lysed bone marrow). Interestingly, proportions of BMNC subpopulations resembled those of lysed bone marrow indicating symmetric BMNC loss independent from the isolation protocol. Hematopoietic stem cell (HSC) content, determined by colony-forming units for granulocytes-macrophages (CFU-GM), was significantly reduced after Ficoll-Paque DGC compared to Percoll DGC and immunomagnetic PMN depletion. Finally, in a proof-of-concept study, we successfully applied the protocol for BMNC isolation by immunodepletion to fresh human bone marrow aspirates. Our findings indicate that the common method to isolate BMNCs in both preclinical and clinical research can be considerably improved by replacing Ficoll-Paque DGC with adapted Percoll DGC, or particularly by immunodepletion of PMNs. 相似文献
119.
Light stimulation of locust (Schistocerca gregaria) photoreceptors results in an actin-dependent translocation of mitochondria towards the photoreceptive microvilli and an antagonistic movement of endoplasmic reticulum towards the cell body. Using immunocytochemical techniques, we have tried to identify myosin-like motors that may drive the light-induced organelle motility. A monoclonal antibody against the motor domain of Acanthamoeba myosin identifies a prominent 110-kDa protein on Western blots of locust retina. Cross-reactivity with two polyclonal anti-myosin antibodies and a monoclonal anti-myosin-I-antibody, together with ATP-dependent binding to actin filaments, provides evidence that the 110-kDa protein is an unconventional myosin. By indirect immunofluorescence, the 110-kDa protein has been localized to both photoreceptors and pigment cells within the retina. In the photoreceptor cells, the 110-kDa protein is bound to the surface of mitochondria. This putative unconventional myosin may thus be a motor protein involved in the light-induced translocation of mitochondria in photoreceptors. 相似文献
120.