全文获取类型
收费全文 | 9676篇 |
免费 | 716篇 |
国内免费 | 4篇 |
专业分类
10396篇 |
出版年
2023年 | 59篇 |
2022年 | 111篇 |
2021年 | 203篇 |
2020年 | 173篇 |
2019年 | 215篇 |
2018年 | 271篇 |
2017年 | 223篇 |
2016年 | 325篇 |
2015年 | 555篇 |
2014年 | 551篇 |
2013年 | 676篇 |
2012年 | 831篇 |
2011年 | 765篇 |
2010年 | 510篇 |
2009年 | 461篇 |
2008年 | 562篇 |
2007年 | 532篇 |
2006年 | 521篇 |
2005年 | 472篇 |
2004年 | 438篇 |
2003年 | 359篇 |
2002年 | 341篇 |
2001年 | 86篇 |
2000年 | 67篇 |
1999年 | 87篇 |
1998年 | 118篇 |
1997年 | 92篇 |
1996年 | 66篇 |
1995年 | 61篇 |
1994年 | 66篇 |
1993年 | 63篇 |
1992年 | 40篇 |
1991年 | 40篇 |
1990年 | 43篇 |
1989年 | 38篇 |
1988年 | 31篇 |
1987年 | 26篇 |
1986年 | 23篇 |
1985年 | 29篇 |
1984年 | 39篇 |
1983年 | 22篇 |
1982年 | 27篇 |
1981年 | 25篇 |
1980年 | 14篇 |
1979年 | 13篇 |
1978年 | 13篇 |
1976年 | 13篇 |
1975年 | 16篇 |
1974年 | 10篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
201.
202.
Carlos Albuquerque Francisco Morinha João Requicha Isabel Dias Henrique Guedes-Pinto Carlos Viegas Estela Bastos 《Gene》2014
Periodontal disease (PD) refers to a group of inflammatory diseases that affect the periodontium, the organ which surrounds and supports the teeth. PD is a highly prevalent disease with a multifactorial etiology and, in humans the individual susceptibility is known to be strongly determined by genetic factors. Several candidate genes have been studied, namely genes related with molecules involved in the inflammatory response. Interleukin-10 (IL-10) is a cytokine with important anti-inflammatory and immunomodulatory roles, and several studies indicate an association between IL10 polymorphisms and PD. In dogs, an important animal model in periodontology, PD is also a highly prevalent naturally occurring disease, and only now are emerging the first studies evaluating the genetic predisposition. In this case–control study, a population of 90 dogs (40 dogs with PD and 50 healthy dogs) was used to study the IL10 gene, and seven new genetic variations in this gene were identified. No statistically significant differences were detected in genotype and allele frequencies of these variations between the PD cases and control groups. Nevertheless, one of the variations (IL10/2_g.285G > A) leads to an amino acid change (glycine to arginine) in the putative signal peptide, being predicted a potential influence on IL-10 protein functionality. Further investigations are important to clarify the biological importance of these new findings. The knowledge of these genetic determinants can help to understand properly the complex causal pathways of PD, with important clinical implications. 相似文献
203.
Lourdes Farre Gabriela Sanz Neus Ruiz-Xivill Manuel Castro de Moura Juan Francisco Martin-Tejera Samuel Gonalves-Ribeiro Maria Martinez-Iniesta Monica Calaf Jose Luis Mosquera Jos Ignacio Martín-Subero Isabel Granada Manel Esteller Eva Domingo-Domenech Fina Climent Alberto Villanueva Anna Sureda 《Disease models & mechanisms》2021,14(7)
204.
Lauren S Vaughn D. Cristopher Bragg Nutan Sharma Sarah Camargos Francisco Cardoso Rekha C Patel 《The Journal of biological chemistry》2015,290(37):22543-22557
PACT is a stress-modulated activator of the interferon-induced double-stranded RNA-activated protein kinase (PKR). Stress-induced phosphorylation of PACT is essential for PACT''s association with PKR leading to PKR activation. PKR activation leads to phosphorylation of translation initiation factor eIF2α inhibition of protein synthesis and apoptosis. A recessively inherited form of early-onset dystonia DYT16 has been recently identified to arise due to a homozygous missense mutation P222L in PACT. To examine if the mutant P222L protein alters the stress-response pathway, we examined the ability of mutant P222L to interact with and activate PKR. Our results indicate that the substitution mutant P222L activates PKR more robustly and for longer duration albeit with slower kinetics in response to the endoplasmic reticulum stress. In addition, the affinity of PACT-PACT and PACT-PKR interactions is enhanced in dystonia patient lymphoblasts, thereby leading to intensified PKR activation and enhanced cellular death. P222L mutation also changes the affinity of PACT-TRBP interaction after cellular stress, thereby offering a mechanism for the delayed PKR activation in response to stress. Our results demonstrate the impact of a dystonia-causing substitution mutation on stress-induced cellular apoptosis. 相似文献
205.
Is it really you,Orthotrichum acuminatum? Ascertaining a new case of intercontinental disjunction in mosses 下载免费PDF全文
Beatriz Vigalondo Francisco Lara Isabel Draper Virginia Valcarcel Ricardo Garilleti Vicente Mazimpaka 《Botanical journal of the Linnean Society. Linnean Society of London》2016,180(1):30-49
Intercontinental disjunct distributions are a main issue in current biogeography. Bryophytes usually have broad distribution ranges and therefore constitute an interesting subject of study in this context. During recent fieldwork in western North America and eastern Africa, we found new populations of a moss morphologically similar to Orthotrichum acuminatum. So far this species has been considered to be one of the most typical epiphytic mosses of the Mediterranean Basin. The new findings raise some puzzling questions. Do these new populations belong to cryptic species or do they belong to O. acuminatum, a species which then has a multiple‐continent disjunct range? In the latter case, how could such an intercontinental disjunction be explained? To answer these questions, an integrative study involving morphological and molecular approaches was conducted. Morphological results reveal that Californian and Ethiopian samples fall within the variability of those from the Mediterranean Basin. Similarly, phylogenetic analyses confirm the monophyly of these populations, showing that O. acuminatum is one of the few moss species with a distribution comprising the western Nearctic, the western Palaearctic and Palaeotropical eastern Africa. Pending a further genetic and phylogeographical study to support or reject the hypothesis, a process of long‐distance dispersal (LDD) is hypothesized to explain this distribution and the origin of the species is suggested to be the Mediterranean Basin, from where diaspores of the species may have migrated to California and Ethiopia. The spore release process in O. acuminatum is revisited to support the LDD hypothesis, © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2016, 180 , 30–49. 相似文献
206.
Maikon Kelbert Aloia Romaní Eduardo Coelho Francisco B. Pereira José A. Teixeira Lucília Domingues 《Bioenergy Research》2016,9(3):750-762
Industrial lignocellulosic bioethanol processes are exposed to different environmental stresses (such as inhibitor compounds, high temperature, and high solid loadings). In this study, a systematic approach was followed where the liquid and solid fractions were mixed to evaluate the influence of varied solid loadings, and different percentages of liquor were used as liquid fraction to determine inhibitor effect. Ethanol production by simultaneous saccharification and fermentation (SSF) of hydrothermally pretreated Eucalyptus globulus wood (EGW) was studied under combined diverse stress operating conditions (30–38 °C, 60–80 g of liquor from hydrothermal treatment or autohydrolysis (containing inhibitor compounds)/100 g of liquid and liquid to solid ratio between 4 and 6.4 g liquid in SSF/g unwashed pretreated EGW) using an industrial Saccharomyces cerevisiae strain supplemented with low-cost byproducts derived from agro-food industry. Evaluation of these variables revealed that the combination of temperature and higher solid loadings was the most significant variable affecting final ethanol concentration and cellulose to ethanol conversion, whereas solid and autohydrolysis liquor loadings had the most significant impact on ethanol productivity. After optimization, an ethanol concentration of 54 g/L (corresponding to 85 % of conversion and 0.51 g/Lh of productivity at 96 h) was obtained at 37 °C using 60 % of autohydrolysis liquor and 16 % solid loading (liquid to solid ratio of 6.4 g/g). The selection of a suitable strain along with nutritional supplementation enabled to produce noticeable ethanol titers in quite restrictive SSF operating conditions, which can reduce operating cost and boost the economic feasibility of lignocellulose-to-ethanol processes. 相似文献
207.
Gemma Aragonès Kalavathi Dasuri Opeoluwa Olukorede Sarah G. Francisco Carol Renneburg Caroline Kumsta Malene Hansen Shun Kageyama Masaaki Komatsu Sheldon Rowan Jonathan Volkin Michael Workman Wenxin Yang Paula Daza Diego Ruano Helena Dominguez‐Martín José Antonio Rodríguez‐Navarro Xue‐Liang Du Michael A. Brownlee Eloy Bejarano Allen Taylor 《Aging cell》2020,19(11)
208.
Arantxa Palacín Cristina Gómez-Casado Luis A. Rivas Jacobo Aguirre Leticia Tordesillas Joan Bartra Carlos Blanco Teresa Carrillo Javier Cuesta-Herranz Consolación de Frutos Genoveva García álvarez-Eire Francisco J. Fernández Pedro Gamboa Rosa Mu?oz Rosa Sánchez-Monge Sofía Sirvent María J. Torres Susana Varela-Losada Rosalía Rodríguez Victor Parro Miguel Blanca Gabriel Salcedo Araceli Díaz-Perales 《PloS one》2012,7(12)
The study of cross-reactivity in allergy is key to both understanding. the allergic response of many patients and providing them with a rational treatment In the present study, protein microarrays and a co-sensitization graph approach were used in conjunction with an allergen microarray immunoassay. This enabled us to include a wide number of proteins and a large number of patients, and to study sensitization profiles among members of the LTP family. Fourteen LTPs from the most frequent plant food-induced allergies in the geographical area studied were printed into a microarray specifically designed for this research. 212 patients with fruit allergy and 117 food-tolerant pollen allergic subjects were recruited from seven regions of Spain with different pollen profiles, and their sera were tested with allergen microarray. This approach has proven itself to be a good tool to study cross-reactivity between members of LTP family, and could become a useful strategy to analyze other families of allergens. 相似文献
209.
210.
Francisco Amaro Aaron P. Turkewitz Ana Martín-González Juan Carlos Gutiérrez 《Biometals》2014,27(1):195-205