全文获取类型
收费全文 | 6358篇 |
免费 | 533篇 |
出版年
2023年 | 35篇 |
2022年 | 32篇 |
2021年 | 159篇 |
2020年 | 85篇 |
2019年 | 135篇 |
2018年 | 166篇 |
2017年 | 157篇 |
2016年 | 224篇 |
2015年 | 351篇 |
2014年 | 377篇 |
2013年 | 507篇 |
2012年 | 596篇 |
2011年 | 539篇 |
2010年 | 349篇 |
2009年 | 266篇 |
2008年 | 387篇 |
2007年 | 404篇 |
2006年 | 354篇 |
2005年 | 298篇 |
2004年 | 282篇 |
2003年 | 259篇 |
2002年 | 237篇 |
2001年 | 66篇 |
2000年 | 48篇 |
1999年 | 60篇 |
1998年 | 55篇 |
1997年 | 36篇 |
1996年 | 30篇 |
1995年 | 29篇 |
1994年 | 22篇 |
1993年 | 19篇 |
1992年 | 43篇 |
1991年 | 26篇 |
1990年 | 23篇 |
1989年 | 23篇 |
1988年 | 22篇 |
1987年 | 15篇 |
1986年 | 18篇 |
1985年 | 18篇 |
1984年 | 13篇 |
1983年 | 19篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1978年 | 7篇 |
1977年 | 10篇 |
1974年 | 6篇 |
1973年 | 9篇 |
1968年 | 8篇 |
1964年 | 6篇 |
排序方式: 共有6891条查询结果,搜索用时 31 毫秒
991.
Microtubule defects in mesenchymal stromal cells distinguish patients with Progressive Supranuclear Palsy 下载免费PDF全文
Alessandra Maria Calogero Mariele Viganò Silvia Budelli Daniela Galimberti Chiara Fenoglio Daniele Cartelli Lorenza Lazzari Petri Lehenkari Margherita Canesi Rosaria Giordano Graziella Cappelletti Gianni Pezzoli 《Journal of cellular and molecular medicine》2018,22(5):2670-2679
Progressive Supranuclear Palsy (PSP) is a rare neurodegenerative disease whose etiopathogenesis remains elusive. The intraneuronal accumulation of hyperphosphorylated Tau, a pivotal protein in regulating microtubules (MT), leads to include PSP into tauopathies. Pathological hallmarks are well known in neural cells but no word yet if PSP‐linked dysfunctions occur also in other cell types. We focused on bone marrow mesenchymal stromal cells (MSCs) that have recently gained attention for therapeutic interventions due to their anti‐inflammatory, antiapoptotic and trophic properties. Here, we aimed to investigate MSCs biology and to disclose if any disease‐linked defect occurs in this non‐neuronal compartment. First, we found that cells obtained from patients showed altered morphology and growth. Next, Western blotting analysis unravelled the imbalance in α‐tubulin post‐translational modifications and in MT stability. Interestingly, MT mass is significantly decreased in patient cells at baseline and differently changes overtime compared to controls, suggesting their inability to efficiently remodel MT cytoskeleton during ageing in culture. Thus, our results provide the first evidence that defects in MT regulation and stability occur and are detectable in a non‐neuronal compartment in patients with PSP. We suggest that MSCs could be a novel model system for unravelling cellular processes implicated in this neurodegenerative disorder. 相似文献
992.
993.
Alessio Molinari Anna Lucia Fallacara Salvatore Di Maria Claudio Zamperini Federica Poggialini Francesca Musumeci Silvia Schenone Adriano Angelucci Alessandro Colapietro Emmanuele Crespan Miroslava Kissova Giovanni Maga Maurizio Botta 《Bioorganic & medicinal chemistry letters》2018,28(21):3454-3457
The proto-oncogene c-Src is a non-receptor tyrosine kinase which is involved in the regulation of many cellular processes, such as differentiation, adhesion and survival. c-Src hyperactivation has been detected in many tumors, including neuroblastoma (NB), one of the major causes of death from neoplasia in infancy. We already reported a large family of pyrazolo[3,4-d]pyrimidines active as c-Src inhibitors. Interestingly, some of these derivatives resulted also active on SH-SY5Y NB cell line. Herein, starting from our previous Free Energy Perturbation/Monte Carlo calculations, we report an optimization study which led to the identification of a new series of derivatives endowed with nanomolar Ki values against c-Src, interesting antiproliferative activity on SH-SY5Y cells and a suitable ADME profile. 相似文献
994.
Riccardo Motti Francesca Ippolito Giuliano Bonanomi 《Human ecology: an interdisciplinary journal》2018,46(4):573-585
Complementary and alternative medicine (CAM) consists of systems and practices used to prevent or treat illness, and/or promote health and wellbeing, generally with herbal remedies. In recent decades, ethnobotanical and ethnopharmacological surveys have received increased attention among populations in central and southern Italy traditionally highly conservative regarding knowledge of folk medicine. This review highlights the use of wild and cultivated plants in paediatric health care. From a search of articles published between 1978 and 2017 we found a total of 34 containing reports of medicinal plants specifically used for treating children’s diseases, listing 83 taxa belonging to 37 families in 116 recorded cases of medicinal plant use. Tuscany has the highest number of plant use reports and the highest number of species used in a single region, followed by Campania and Sicily. Allium sativum is the most widely reported species, cited in eight regions. We identified eight ailment categories. Plants used as anthelmintics and for gastro-intestinal and skin diseases are widely used. 相似文献
995.
996.
Detection and typing of amyloid deposits in tissues are two crucial steps in the management of systemic amyloidoses. The presence of amyloid deposits is routinely evaluated through Congo red staining, whereas proteomics is now a mainstay in the identification of the deposited proteins. In article number 1700236, Winter et al. [Proteomics 2017, 17, Issue 22] describe a novel method based on MALDI–MS imaging coupled to ion mobility separation and peptide filtering, to detect the presence of amyloid in histology samples and to identify its composition, while preserving the spatial distribution of proteins in tissues. 相似文献
997.
1,3‐Regiospecific ethanolysis of soybean oil catalyzed by crosslinked porcine pancreas lipase aggregates 下载免费PDF全文
Margarita D. Ramos Letícia P. Miranda Raquel L. C. Giordano Roberto Fernandez‐Lafuente William Kopp Paulo W. Tardioli 《Biotechnology progress》2018,34(4):910-920
The preparation of crosslinked aggregates of pancreatic porcine lipase (PPL‐CLEA) was systematically studied, evaluating the influence of three precipitants and two crosslinking agents, as well as the use of soy protein as an alternative feeder protein on the catalytic properties and stability of the immobilized PPL. Standard CLEAs showed a global yield (CLEA’ observed activity/offered total activity) of less than 4%, whereas with the addition of soy protein (PPL:soy protein mass ratio of 1:3) the global yield was approximately fivefold higher. The CLEA of PPL prepared with soy protein as feeder (PPL:soy protein mass ratio of 1:3) and glutaraldehyde as crosslinking reagent (10 μmol of aldehyde groups/mg of total protein) was more active mainly because of the reduced enzyme leaching in the washing step. This CLEA, named PPL‐SOY‐CLEA, had an immobilization yield around 60% and an expressed activity around 40%. In the ethanolysis of soybean oil, the PPL‐SOY‐CLEA yielded maximum fatty acid ethyl ester (FAEE) concentration around 12‐fold higher than that achieved using soluble PPL (34 h reaction at 30°C, 300 rpm stirring, soybean oil/ethanol molar ratio of 1:5) with an enzyme load around 2‐fold lower (very likely due to free enzyme inactivation). The operational stability of the PPL‐SOY‐CLEA in the ethanolysis of soybean oil in a vortex flow type reactor showed that FAEE yield was higher than 50% during ten reaction cycles of 24 h. This reactor configuration may be an attractive alternative to the conventional stirred reactors for biotransformations in industrial plants using carrier‐free biocatalysts. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:910–920, 2018 相似文献
998.
This study examined the genetic diversity of small-spored Alternaria species in the southwest desert of the USA by sampling 552 isolates from different habitats (soil and plant debris) in different locations (urban and an undisturbed desert). To estimate the genetic diversity, Amplified Fragment Length Polymorphism (AFLP) fingerprinting analysis was performed for all isolates. Strains representative of the sampled genotypic diversity (n = 125) were further characterized according their sporulation pattern and the capability to produce allergens. Morphological characterization assigned the majority of the strains to the Alternaria alternata and Alternaria tenuissima morpho-groups with only two isolates assigned to the Alternaria arborescens morpho-group. AFLP fingerprinting differentiated the A. arborescens morpho-groups, but could not distinguish between the A. alternata and A. tenuissima morpho-groups. Western blot analysis showed that a large number of allergenic proteins were produced by strains. These proteins were not specific for any morpho-group nor source of isolation. A hierarchical analysis of molecular variance was performed on the AFLP data to quantify molecular variation and partition this variation among sampled locations and habitat. No statistically significant differentiation among locations and habitat was detected indicating a lack of population structure across environments. 相似文献
999.
Vanessa Capone Emanuela Clemente Elena Restelli Antonella Di Campli Samantha Sperduti Francesca Ornaghi Laura Pietrangelo Feliciano Protasi Roberto Chiesa Michele Sallese 《生物化学与生物物理学报:疾病的分子基础》2018,1864(10):3164-3180
Loss-of-function mutations in the SIL1 gene are linked to Marinesco-Sjögren syndrome (MSS), a rare multisystem disease of infancy characterized by cerebellar and skeletal muscle degeneration. SIL1 is a ubiquitous adenine nucleotide exchange factor for the endoplasmic reticulum (ER) chaperone BiP. The complexity of mechanisms by which loss of SIL1 causes MSS is not yet fully understood. We used HeLa cells to test the hypothesis that impaired protein folding in the ER due to loss of SIL1 could affect secretory trafficking, impairing the transport of cargoes essential for the function of MSS vulnerable cells. Immunofluorescence and ultrastructural analysis of SIL1-knocked-down cells detected ER chaperone aggregation, enlargement of the Golgi complex, increased autophagic vacuoles, and mitochondrial swelling. SIL1-interefered cells also had delayed ER-to-plasma membrane transport with retention of Na+/K+-ATPase and procollagen-I in the ER and Golgi, and increased apoptosis. The PERK pathway of the unfolded protein response was activated in SIL1-interfered cells, and the PERK inhibitor GSK2606414 attenuated the morphological and functional alterations of the secretory pathway, and significantly reduced cell death. These results indicate that loss of SIL1 is associated with alterations of secretory transport, and suggest that inhibiting PERK signalling may alleviate the cellular pathology of SIL1-related MSS. 相似文献
1000.
Giorgia Letizia Marcone Elisa Binda Francesca Berini Flavia Marinelli 《Biotechnology advances》2018,36(2):534-554
Glycopeptide antibiotics are drugs of last resort for treating severe infections caused by multi-drug resistant Gram-positive pathogens. First-generation glycopeptides (vancomycin and teicoplanin) are produced by soil-dwelling actinomycetes. Second-generation glycopeptides (dalbavancin, oritavancin, and telavancin) are semi-synthetic derivatives of the progenitor natural products. Herein, we cover past and present biotechnological approaches for searching for and producing old and new glycopeptide antibiotics. We review the strategies adopted to increase microbial production (from classical strain improvement to rational genetic engineering), and the recent progress in genome mining, chemoenzymatic derivatization, and combinatorial biosynthesis for expanding glycopeptide chemical diversity and tackling the never-ceasing evolution of antibiotic resistance. 相似文献