全文获取类型
收费全文 | 334篇 |
免费 | 21篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 7篇 |
2020年 | 8篇 |
2019年 | 6篇 |
2018年 | 12篇 |
2017年 | 4篇 |
2016年 | 11篇 |
2015年 | 14篇 |
2014年 | 22篇 |
2013年 | 22篇 |
2012年 | 28篇 |
2011年 | 26篇 |
2010年 | 11篇 |
2009年 | 13篇 |
2008年 | 21篇 |
2007年 | 10篇 |
2006年 | 15篇 |
2005年 | 11篇 |
2004年 | 15篇 |
2003年 | 12篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1968年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有355条查询结果,搜索用时 31 毫秒
11.
Adrián Pablos Ignacio Martínez Carlos Lorenzo Ana Gracia Nohemi Sala Juan Luis Arsuaga 《Journal of human evolution》2013
Here we present and describe comparatively 25 talus bones from the Middle Pleistocene site of the Sima de los Huesos (SH) (Sierra de Atapuerca, Burgos, Spain). These tali belong to 14 individuals (11 adult and three immature). Although variation among Middle and Late Pleistocene tali tends to be subtle, this study has identified unique morphological characteristics of the SH tali. They are vertically shorter than those of Late Pleistocene Homo sapiens, and show a shorter head and a broader lateral malleolar facet than all of the samples. Moreover, a few shared characters with Neanderthals are consistent with the hypothesis that the SH population and Neanderthals are sister groups. These shared characters are a broad lateral malleolar facet, a trochlear height intermediate between modern humans and Late Pleistocene H. sapiens, and a short middle calcaneal facet. It has been possible to propose sex assignment for the SH tali based on their size. Stature estimates based on these fossils give a mean stature of 174.4 cm for males and 161.9 cm for females, similar to that obtained based on the long bones from this same site. 相似文献
12.
William G. Meikle Marie-Claude Bon Steve C. Cook Carlos Gracia Stefan T. Jaronski 《Biocontrol Science and Technology》2013,23(2):220-233
Two strains of Pseudomonas fluorescens were found contaminating a biopesticide used in a previous study against Varroa destructor infestations in honey bee hives. In that study, the biopesticide, a formulation of a fungal pathogen of arthropods, Beauveria bassiana, failed to have any negative impact on the mite infestation despite successful results in previous studies using uncontaminated batches of the same biopesticide. The objective of the present research was to determine whether the bacteria may have interfered with the infectivity and/or virulence of B. bassiana in a simplified system; positive results in that system would then provide a rationale for further work under more complex conditions. Galleria mellonella late instar larvae treated topically with both a bacterial suspension of 6.8 to 7.0×107 cfu/ml and a fungal suspension of 2.5×107 or 2.5×108 B. bassiana conidia/ml showed, in the case of one of the bacterial strains, significantly increased survivorship compared to larvae treated with just the B. bassiana suspension. When larvae were immersed in a bacterial suspension prior to application of B. bassiana suspension using a spray tower, a significant positive effect of the same P. fluorescens strain on larval survivorship was observed at 2.5×108 conidia/ml. Neither the bacterial suspensions alone nor blank control solutions had any effect on larval survivorship. These results show that an interaction between the bacteria and the pathogen may explain some of the results from the prior field trial. 相似文献
13.
Toward a Low‐Cost Artificial Leaf: Driving Carbon‐Based and Bifunctional Catalyst Electrodes with Solution‐Processed Perovskite Photovoltaics
下载免费PDF全文
![点击此处可从《Liver Transplantation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Tiva Sharifi Christian Larsen Jia Wang Wai Ling Kwong Eduardo Gracia‐Espino Guillaume Mercier Johannes Messinger Thomas Wågberg Ludvig Edman 《Liver Transplantation》2016,6(20)
Molecular hydrogen can be generated renewably by water splitting with an “artificial‐leaf device”, which essentially comprises two electrocatalyst electrodes immersed in water and powered by photovoltaics. Ideally, this device should operate efficiently and be fabricated with cost‐efficient means using earth‐abundant materials. Here, a lightweight electrocatalyst electrode, comprising large surface‐area NiCo2O4 nanorods that are firmly anchored onto a carbon–paper current collector via a dense network of nitrogen‐doped carbon nanotubes is presented. This electrocatalyst electrode is bifunctional in that it can efficiently operate as both anode and cathode in the same alkaline solution, as quantified by a delivered current density of 10 mA cm?2 at an overpotential of 400 mV for each of the oxygen and hydrogen evolution reactions. By driving two such identical electrodes with a solution‐processed thin‐film perovskite photovoltaic assembly, a wired artificial‐leaf device is obtained that features a Faradaic H2 evolution efficiency of 100%, and a solar‐to‐hydrogen conversion efficiency of 6.2%. A detailed cost analysis is presented, which implies that the material‐payback time of this device is of the order of 100 days. 相似文献
14.
Greg Clark Josh Russell Peter Enyeart Brant Gracia Aimee Wessel Inga Jarmoskaite Damon Polioudakis Yoel Stuart Tony Gonzalez Al MacKrell Stacia Rodenbusch Gwendolyn M. Stovall Josh T. Beckham Michael Montgomery Tania Tasneem Jack Jones Sarah Simmons Stanley Roux 《PLoS biology》2016,14(2)
Both scientists and the public would benefit from improved communication of basic scientific research and from integrating scientists into education outreach, but opportunities to support these efforts are limited. We have developed two low-cost programs—"Present Your PhD Thesis to a 12-Year-Old" and "Shadow a Scientist”—that combine training in science communication with outreach to area middle schools. We assessed the outcomes of these programs and found a 2-fold benefit: scientists improve their communication skills by explaining basic science research to a general audience, and students'' enthusiasm for science and their scientific knowledge are increased. Here we present details about both programs, along with our assessment of them, and discuss the feasibility of exporting these programs to other universities. 相似文献
15.
16.
Anabel Fernndez‐Iglesias Martí Ortega‐Ribera Sergi Guix‐Muntet Jordi Gracia‐Sancho 《Journal of cellular and molecular medicine》2019,23(2):877-886
Liver cells isolated from pre‐clinical models are essential tools for studying liver (patho)physiology, and also for screening new therapeutic options. We aimed at developing a new antibody‐free isolation method able to obtain the four main hepatic cell types (hepatocytes, liver sinusoidal endothelial cells [LSEC], hepatic macrophages [HMΦ] and hepatic stellate cells [HSC]) from a single rat liver. Control and cirrhotic (CCl4 and TAA) rat livers (n = 6) were perfused, digested with collagenase and mechanically disaggregated obtaining a multicellular suspension. Hepatocytes were purified by low revolution centrifugations while non‐parenchymal cells were subjected to differential centrifugation. Two different fractions were obtained: HSC and mixed LSEC + HMΦ. Further LSEC and HMΦ enrichment was achieved by selective adherence time to collagen‐coated substrates. Isolated cells showed high viability (80%‐95%) and purity (>95%) and were characterized as functional: hepatocytes synthetized albumin and urea, LSEC maintained endocytic capacity and in vivo fenestrae distribution, HMΦ increased expression of inflammatory markers in response to LPS and HSC were activated upon in vitro culture. The 4 in 1 protocol allows the simultaneous isolation of highly pure and functional hepatic cell sub‐populations from control or cirrhotic single livers without antibody selection. 相似文献
17.
18.
Emma Roig-Molina Mirian Domenech María de Gracia Retamosa Montserrat Nácher-Vázquez Luis Rivas Beatriz Maestro Pedro García Ernesto García Jesús M. Sanz 《Biochimica et Biophysica Acta (BBA)/General Subjects》2019,1863(1):96-104
Antibiotic resistance is a global current threat of increasing importance. Moreover, biofilms represent a medical challenge since the inherent antibiotic resistance of their producers demands the use of high doses of antibiotics over prolonged periods. Frequently, these therapeutic measures fail, contributing to bacterial persistence, therefore demanding the development of novel antimicrobials. Esters of bicyclic amines (EBAs), which are strong inhibitors of Streptococcus pneumoniae growth, were initially designed as inhibitors of pneumococcal choline-binding proteins on the basis of their structural analogy to the choline residues in the cell wall. However, instead of mimicking the characteristic cell chaining phenotype caused by exogenously added choline on planktonic cultures of pneumococcal cells, EBAs showed an unexpected lytic activity. In this work we demonstrate that EBAs display a second, and even more important, function as cell membrane destabilizers. We then assayed the inhibitory and disintegrating activity of these molecules on pneumococcal biofilms. The selected compound (EBA 31) produced the highest effect on S. pneumoniae (encapsulated and non-encapsulated) biofilms at very low concentrations. EBA 31 was also effective on mixed biofilms of non-encapsulated S. pneumoniae plus non-typeable Haemophilus influenzae, two pathogens frequently forming a self-produced biofilm in the human nasopharynx. These results support the role of EBAs as a promising alternative for the development of novel, broad-range antimicrobial drugs encompassing both Gram-positive and Gram-negative pathogens. 相似文献
19.
Marco Lupattelli Paolo Tini Valerio Nardone Cynthia Aristei Simona Borghesi Ernesto Maranzano Paola Anselmo Gianluca Ingrosso Letizia Deantonio Michela Buglione di Monale e Bastia 《Reports of Practical Oncology and Radiotherapy》2022,27(1):15
Brain metastases, the most common metastases in adults, will develop in up to 40% of cancer patients, accounting for more than one-half of all intracranial tumors. They are most associated with breast and lung cancer, melanoma and, less frequently, colorectal and kidney carcinoma.Magnetic resonance imaging (MRI) is the gold standard for diagnosis. For the treatment plan, computed tomography (CT ) images are co-registered and fused with a gadolinium-enhanced T1-weighted MRI where tumor volume and organs at risk are contoured. Alternatively, plain and contrast-enhanced CT scans are co-registered. Single-fraction stereotactic radiotherapy (SRT ) is used to treat patients with good performance status and up to 4 lesions with a diameter of 30 mm or less that are distant from crucial brain function areas. Fractionated SRT (2–5 fractions) is used for larger lesions, in eloquent areas or in proximity to crucial or surgically inaccessible areas and to reduce treatment-related neurotoxicity. The single-fraction SRT dose, which depends on tumor diameter, impacts local control. Fractionated SRT may encompass different schedules. No randomized trial data compared the safety and efficacy of single and multiple fractions. Both single-fraction and fractionated SRT provide satisfactory local control rates, tolerance, a low risk of transient acute adverse events and of radiation necrosis the incidence of which correlated with the irradiated brain volume. 相似文献
20.
Morphological and agronomical diversity patterns in the Spanish barley core collection 总被引:1,自引:0,他引:1
Lasa JM Igartua E Ciudad FJ Codesal P García EV Gracia MP Medina B Romagosa I Molina-Cano JL Montoya JL 《Hereditas》2001,135(2-3):217-225
Seven thousand years of barley cultivation under the environmental hardships typical of the Mediterranean climate have generated genetic singularity of the Spanish barleys, consistently reported in the literature. From the Spanish National Collection of 2289 accessions, a core subset with 159 landraces and 16 old varieties was constituted. Twenty-seven characters were evaluated for the core collection, to define the structure of the diversity. Several evaluation trials were carried out in 1999-2000, whereas yield trials were performed in earlier years. Phenotypic diversity was large for most of the characters studied. Comparisons of genetic diversity between the core and the original collections suggested that the core is a good representation of the existing diversity in the BNG. Comparisons with results of studies on Spanish materials from other collections seem to indicate that the Spanish diversity is not well represented in some world collections. Principal component analyses for quantitative and qualitative characters revealed a clear distinction between two- and six-row cultivars, and also between landraces and commercial varieties. Geographical origins of the landraces were correlated with grain yield, heading date, duration of grain filling period, and growth class. In relation to diseases, altitude played an important role on the resistance to powdery mildew and brown rust. For brown rust, all the resistant landraces came from low altitudes. These geographical gradients seemed consistent with prior knowledge about barley adaptation, and would confirm the agreement between passport data and true adaptive origin of these landraces from a geographical point of view. 相似文献