全文获取类型
收费全文 | 1819篇 |
免费 | 187篇 |
国内免费 | 1篇 |
出版年
2023年 | 11篇 |
2022年 | 14篇 |
2021年 | 28篇 |
2020年 | 26篇 |
2019年 | 24篇 |
2018年 | 43篇 |
2017年 | 22篇 |
2016年 | 55篇 |
2015年 | 68篇 |
2014年 | 92篇 |
2013年 | 111篇 |
2012年 | 156篇 |
2011年 | 126篇 |
2010年 | 65篇 |
2009年 | 77篇 |
2008年 | 81篇 |
2007年 | 84篇 |
2006年 | 72篇 |
2005年 | 61篇 |
2004年 | 76篇 |
2003年 | 55篇 |
2002年 | 50篇 |
2001年 | 62篇 |
2000年 | 45篇 |
1999年 | 40篇 |
1998年 | 28篇 |
1997年 | 35篇 |
1996年 | 24篇 |
1995年 | 14篇 |
1994年 | 21篇 |
1993年 | 17篇 |
1992年 | 49篇 |
1991年 | 31篇 |
1990年 | 27篇 |
1989年 | 22篇 |
1988年 | 25篇 |
1987年 | 19篇 |
1986年 | 22篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 9篇 |
1977年 | 11篇 |
1976年 | 6篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1972年 | 6篇 |
1970年 | 7篇 |
排序方式: 共有2007条查询结果,搜索用时 31 毫秒
71.
Augusto García Villanueva María Jesús García Villanueva Mercedes García Villanueva Roberto Rojo Blanco María Vicenta Collado Guirao Jacobo Cabañas Montero Rafael Beni Pérez Irene Moreno Montes 《Endocrinología y nutrición》2013,60(5):254-259
Amyloidosis is an uncommon syndrome consisting of a number of disorders having in common an extracellular deposit of fibrillary proteins. This results in functional and structural changes in the affected organs, depending on deposit location and severity.Amyloid infiltration of the thyroid gland may occur in 50% and up to 80% of patients with primary and secondary amyloidosis respectively. Amyloid goiter (AG) is a true rarity, usually found associated to secondary amyloidosis. AG may require surgical excision, usually because of compressive symptoms.We report the case of a patient with a big AG occurring in the course of a secondary amyloidosis associated to polyarticular onset juvenile idiopathic arthritis who underwent total thyroidectomy. Current literature is reviewed, an attempt is made to provide action guidelines, and some surgical considerations on this rare condition are given. 相似文献
72.
73.
74.
Juan P. de-Torres David Blanco Ana B. Alcaide Luis M. Seijo Gorka Bastarrika María José Pajares Arrate Mu?oz-Barrutia Carlos Ortiz-de-Solorzano Ruben Pio Arantza Campo Usua Montes Victor Segura Jesús Pueyo Luis M. Montuenga Javier J. Zulueta 《PloS one》2013,8(4)
Rationale
Low-grade inflammation and emphysema have been shown to be associated with an increased risk of lung cancer. However, the systemic inflammatory response in patients with emphysema is still unknown.Objective
To compare the plasma cytokine profiles in two groups of current or former smokers without airway obstruction: a control group of individuals without computed tomography (CT) detected emphysema vs. a study group of individuals with CT detected emphysema.Methods
Subjects underwent a chest CT, spirometry, and determination of EGF, IL-15, IL-1ra, IL-8, MCP-1, MIP-1β, TGFα, TNFα, and VEGF levels in plasma. Cytokine levels in each group were compared adjusting for confounding factors.Results
160 current smokers and former smokers without airway obstruction participated in the study: 80 without emphysema and 80 subjects with emphysema. Adjusted group comparisons revealed significant reductions in EGF (−0.317, p = 0.01), IL-15 (−0.21, p = 0.01), IL-8 (−0.180, p = 0.02) and IL-1ra (−0.220, p = 0.03) in subjects with emphysema and normal spirometry.Conclusions
Current or former smokers expressing a well-defined disease characteristic such as emphysema, has a specific plasma cytokine profile. This includes a decrease of cytokines mainly implicated in activation of apoptosis or decrease of immunosurveillance. This information should be taken into account when evaluated patients with tobacco respiratory diseases. 相似文献75.
Francisco Campos Tomás Sobrino Alba Vieites-Prado María Pérez-Mato Manuel Rodríguez-Yá?ez Miguel Blanco José Castillo 《PloS one》2013,8(11)
Hyperthermia is a predictor of poor outcome in ischemic (IS) and intracerebral hemorrhagic (ICH) stroke. Our aim was to study the plausible mechanisms involved in the poor outcome associated to hyperthermia in stroke. We conducted a case-control study including patients with IS (n = 100) and ICH (n = 100) within the first 12 hours from symptom onset. Specifically, IS and ICH patients were consecutively included into 2 subgroups, according to the highest body temperature within the first 24 hours: Tmax <37.5°C and Tmax ≥37.5°C, up to reach 50 patients per subgroup of temperature for both IS and ICH patients. Body temperature was determined at admission and every 4 hours during the first 48 hours. Main outcome variable was poor functional outcome (modified Rankin scale score >2) at 3 months. Serum levels of glutamate and active MMP-9 were measured at admission. Our results showed that Tmax ≥37.5°C within the first 24 hours was independently associated with poor outcome in both IS (OR, 12.43; 95% CI, 3.73–41.48; p<0.0001) and ICH (OR, 4.29; 95% CI, 1.32–13.91; p = 0.015) after adjusting for variables with a proven biological relevance for outcome. However, when molecular markers levels were included in the logistic regression model, we observed that glutamate (OR, 1.01; 95% CI, 1.00–1.02; p = 0.001) and infarct volume (OR, 1.06; 95% CI, 1.01–1.10; p = 0.015) were the only variables independently associated to poor outcome in IS, and active MMP-9 (OR, 1.04; 95% CI, 1.00–1.08; p = 0.002) and National Institute of Health Stroke Scale (NIHSS) at admission (OR, 1.29; 95% CI, 1.13–1.49; p<0.0001) in ICH. In conclusion, these results suggest that although the outcome associated to hyperthermia is similar in human IS and ICH, the underlying mechanisms may be different. 相似文献
76.
Edurne Blanco Patricia Reglero Aurelio Ortega Arild Folkvord Fernando de la Gándara Alma Hernández de Rojas Marta Moyano 《Journal of fish biology》2020,97(5):1296-1305
Atlantic bluefin tuna is an iconic scombrid species with a high commercial and ecological value. Despite their importance, many physiological aspects, especially during the larval stages, are still unknown. Metabolic rates are one of the understudied aspects in scombrid larvae, likely due to challenges associated to larval handling before and during respirometry trials. Gaining reliable estimates of metabolic rates is essential to understand how larvae balance their high growth needs and activity and other physiological functions, which can be very useful for fisheries ecology and aquaculture. This is the first study to (a) estimate the relationship between routine metabolic rate (RMR) and larval dry weight (DW) (mass scaling exponent) at a constant temperature of 26°C, (b) measure the RMR under light and darkness and (c) test whether the interindividual differences in the RMR are related to larval nutritional status (RNA/DNA and DNA/DW). The RMR scaled nearly isometrically with body size (b = 0.99, 0.60–31.56 mg DW) in contrast to the allometric relationship observed in most fish larvae (average b = 0.87). The results show no significant differences in larval RMR under light and darkness, suggesting similar larval activity levels in both conditions. The size explained most of the variability in RMR (97%), and nutritional condition was unrelated to the interindividual differences in routine metabolism. This is the first study to report the metabolic rates of Atlantic bluefin tuna larvae and discuss the challenges of performing bioenergetic studies with early life stages of scombrids. 相似文献
77.
Noelia Blanco Ambrose J. Williams Danming Tang Dejin Zhan Shahram Misaghi Robert F. Kelley Laura C. Simmons 《Biotechnology and bioengineering》2020,117(7):1946-1960
Optimal production of bispecific antibodies (bsAb) requires efficient and tailored co-expression and assembly of two distinct heavy and two distinct light chains. Here, we describe a novel technology to modulate the translational strength of antibody chains via Kozak sequence variants to produce bsAb in a single cell line. In this study, we designed and screened a large Kozak sequence library to identify 10 independent variants that can modulate protein expression levels from approximately 0.2 to 1.3-fold compared with the wild-type sequence in transient transfection. We used a combination of several of these variants, covering a wide range of translational strength, to develop stable single cell Chinese hamster ovary bispecific cell lines and compared the results with those obtained from the wild-type sequence. A significant increase in bispecific antibody assembly with a concomitant reduction in the level of product-related impurities was observed. Our findings suggest that for production of bsAb it can be advantageous to modify translational strength for selected protein chains to improve overall yield and product quality. By extension, tuning of translational strength can also be applied to improving the production of a wide variety of heterologous proteins. 相似文献
78.
Francisco Blanco German Urbina-Villalba M. M. Ramirez De Agudelo 《Molecular simulation》2013,39(3):165-176
Abstract The experimental determination of Al siting in zeolites involves the use of multiple techniques. Great effort has been made on both, experimental and theoretical approaches. The present study presents a novel methodology for calculating Al/Si replacement energies. Simple semiempirical calculations were applied on Modenite, Ferrierite and ZSM-5 zeolites, resulting in good agreement with the experimetal evidences. We have found that the favored Al substitution sites are T3 and T4 in Mordenite, while T2 and T4 are in Ferrierite, and only the T9 site is favored in ZSM-5. The method presented is based on an average of partial Al/Si replacement energies, evaluated for all rings belonging to each T site, rather than in the calculation of a total replacement energy evaluated for only one representative aggregate. 相似文献
79.
Fábio Takenori Higa Lucila Okuyama Fukasawa Maria Gisele Gon?alves Maristela Marques Salgado Ana Paula Silva de Lemos Lee H Harrison Priscilla Lima de Oliveira Carla Naufal da Silva Claudio Tavares Sacchi 《Memórias do Instituto Oswaldo Cruz》2013,108(2):246-247
We evaluated the use of a newly described sodC-based real-time-polymerase chain reaction (RT-PCR) assay for detecting Neisseria meningitidis in normally sterile sites, such as cerebrospinal fluid and serum. The sodC-based RT-PCR assay has an advantage over ctrA for detecting nongroupable N. meningitidis isolates, which are commonly present in asymptomatic pharyngeal carriage. However, in our study, sodC-based RT-PCR was 7.5% less sensitive than ctrA. Given the public health impact of possible false-negative results due to the use of the sodC target gene alone, sodC-based RT-PCR for the diagnosis of meningococcal meningitis should be used with caution. 相似文献
80.
Anthropogenic global climate change is expected to cause severe range contractions among alpine plants. Alpine areas in the Mediterranean region are of special concern because of the high abundance of endemic species with narrow ranges. This study combined species distribution models, population structure analyses and Bayesian skyline plots to trace the past and future distribution and diversity of Linaria glacialis, an endangered narrow endemic species that inhabits summits of Sierra Nevada (Spain). The results showed that: (i) the habitat of this alpine‐Mediterranean species in Sierra Nevada suffered little changes during glacial and interglacial stages of late Quaternary; (ii) climatic oscillations in the last millennium (Medieval Warm Period and Little Ice Age) moderately affected the demographic trends of L. glacialis; (iii) future warming conditions will cause severe range contractions; and (iv) genetic diversity will not diminish at the same pace as the distribution range. As a consequence of the low population structure of this species, genetic impoverishment in the alpine zones of Sierra Nevada should be limited during range contraction. We conclude that maintenance of large effective population sizes via high mutation rates and high levels of gene flow may promote the resilience of alpine plant species when confronted with global warming. 相似文献