全文获取类型
收费全文 | 2033篇 |
免费 | 136篇 |
出版年
2022年 | 24篇 |
2021年 | 34篇 |
2020年 | 31篇 |
2019年 | 43篇 |
2018年 | 54篇 |
2017年 | 40篇 |
2016年 | 54篇 |
2015年 | 95篇 |
2014年 | 78篇 |
2013年 | 146篇 |
2012年 | 177篇 |
2011年 | 140篇 |
2010年 | 83篇 |
2009年 | 70篇 |
2008年 | 116篇 |
2007年 | 128篇 |
2006年 | 102篇 |
2005年 | 92篇 |
2004年 | 104篇 |
2003年 | 89篇 |
2002年 | 78篇 |
2001年 | 24篇 |
2000年 | 24篇 |
1999年 | 23篇 |
1998年 | 22篇 |
1997年 | 16篇 |
1996年 | 14篇 |
1995年 | 13篇 |
1994年 | 14篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 9篇 |
1990年 | 10篇 |
1989年 | 8篇 |
1986年 | 14篇 |
1985年 | 16篇 |
1984年 | 11篇 |
1982年 | 7篇 |
1981年 | 13篇 |
1979年 | 11篇 |
1978年 | 7篇 |
1977年 | 9篇 |
1976年 | 6篇 |
1975年 | 10篇 |
1974年 | 7篇 |
1973年 | 9篇 |
1970年 | 7篇 |
1969年 | 7篇 |
1968年 | 7篇 |
1967年 | 11篇 |
排序方式: 共有2169条查询结果,搜索用时 727 毫秒
861.
Four known isoprenoids were isolated from Lemna minor besides a novel diterpene which was attributed the structure (4R)-4-hydroxyisophytol by spectroscopic studies and chemical correlation. 相似文献
862.
863.
Pietro K. Maruyama Jeferson Vizentin‐Bugoni Jesper Sonne Ana M. Martín González Matthias Schleuning Andréa C. Araujo Andrea C. Baquero Juliana Cardona Paola Cardona Peter A. Cotton Glauco Kohler Carlos Lara Tiago Malucelli Oscar Humberto Marín‐Gómez Jeff Ollerton Ana M. Rui Allan Timmermann Isabela G. Varassin Thais B. Zanata Carsten Rahbek Marlies Sazima Bo Dalsgaard 《Diversity & distributions》2016,22(6):i-i
864.
Roberta Palorini Giuseppina Votta Yuri Pirola Humberto De Vitto Sara De Palma Cristina Airoldi Michele Vasso Francesca Ricciardiello Pietro Paolo Lombardi Claudia Cirulli Raffaella Rizzi Francesco Nicotra Karsten Hiller Cecilia Gelfi Lilia Alberghina Ferdinando Chiaradonna 《PLoS genetics》2016,12(3)
Cancer cells often rely on glycolysis to obtain energy and support anabolic growth. Several studies showed that glycolytic cells are susceptible to cell death when subjected to low glucose availability or to lack of glucose. However, some cancer cells, including glycolytic ones, can efficiently acquire higher tolerance to glucose depletion, leading to their survival and aggressiveness. Although increased resistance to glucose starvation has been shown to be a consequence of signaling pathways and compensatory metabolic routes activation, the full repertoire of the underlying molecular alterations remain elusive. Using omics and computational analyses, we found that cyclic adenosine monophosphate-Protein Kinase A (cAMP-PKA) axis activation is fundamental for cancer cell resistance to glucose starvation and anoikis. Notably, here we show that such a PKA-dependent survival is mediated by parallel activation of autophagy and glutamine utilization that in concert concur to attenuate the endoplasmic reticulum (ER) stress and to sustain cell anabolism. Indeed, the inhibition of PKA-mediated autophagy or glutamine metabolism increased the level of cell death, suggesting that the induction of autophagy and metabolic rewiring by PKA is important for cancer cellular survival under glucose starvation. Importantly, both processes actively participate to cancer cell survival mediated by suspension-activated PKA as well. In addition we identify also a PKA/Src mechanism capable to protect cancer cells from anoikis. Our results reveal for the first time the role of the versatile PKA in cancer cells survival under chronic glucose starvation and anoikis and may be a novel potential target for cancer treatment. 相似文献
865.
Farzana Islam Rume Alessia Affuso Luigina Serrecchia Valeria Rondinone Viviana Manzulli Emanuele Campese Pietro Di Taranto Paritosh Kumar Biswas Chowdhury Rafiqul Ahsan Mahmuda Yasmin Antonio Fasanella Martin Hugh-Jones 《PloS one》2016,11(4)
In Bangladesh, anthrax, caused by the bacterium Bacillus anthracis, is considered an endemic disease affecting ruminants with sporadic zoonotic occurrences in humans. Due to the lack of knowledge about risks from an incorrect removal of infected carcasses, the disease is not properly monitored, and because of the socio-economic conditions, the situation is under-reported and under-diagnosed. For sensitive species, anthrax represents a fatal outcome with sudden death and sometimes bleeding from natural orifices. The most common source of infection for ruminants is ingestion of spores during grazing in contaminated pastures or through grass and water contaminated with anthrax spores. Domestic cattle, sheep and goats can also become infected through contaminated bone meal (used as feed) originating from anthrax-infected carcasses. The present investigation was conducted to isolate B. anthracis organisms from 169 samples (73 soil, 1 tissue, 4 bone and 91 bone meal samples) collected from 12 different districts of Bangladesh. The sampling was carried out from 2012 to 2015. Twelve samples resulted positive for B. anthracis. Biomolecular analyses were conducted starting from the Canonical Single Nucleotide Polymorphism (CanSNP) to analyze the phylogenetic origin of strains. The analysis of genotype, obtained through the Multiple Locus Variable Number Tandem Repeat Analysis (MLVA) with the analysis of 15 Variable Number Tandem Repeats (VNTR), demonstrated four different genotypes: two of them were previously identified in the district of Sirajganj. The sub-genotyping, conducted with Single Nucleotide Repeats analysis, revealed the presence of eight subgenotypes. The data of the present study concluded that there was no observed correlation between imported cattle feed and anthrax occurrence in Bangladesh and that the remarkable genetic variations of B. anthracis were found in the soil of numerous outbreaks in this country. 相似文献
866.
Nicole Weisschuh Anja K. Mayer Tim M. Strom Susanne Kohl Nicola Gl?ckle Max Schubach Sten Andreasson Antje Bernd David G. Birch Christian P. Hamel John R. Heckenlively Samuel G. Jacobson Christina Kamme Ulrich Kellner Erdmute Kunstmann Pietro Maffei Charlotte M. Reiff Klaus Rohrschneider Thomas Rosenberg Günther Rudolph Rita Vámos Balázs Varsányi Richard G. Weleber Bernd Wissinger 《PloS one》2016,11(1)
Retinal dystrophies (RD) constitute a group of blinding diseases that are characterized by clinical variability and pronounced genetic heterogeneity. The different nonsyndromic and syndromic forms of RD can be attributed to mutations in more than 200 genes. Consequently, next generation sequencing (NGS) technologies are among the most promising approaches to identify mutations in RD. We screened a large cohort of patients comprising 89 independent cases and families with various subforms of RD applying different NGS platforms. While mutation screening in 50 cases was performed using a RD gene capture panel, 47 cases were analyzed using whole exome sequencing. One family was analyzed using whole genome sequencing. A detection rate of 61% was achieved including mutations in 34 known and two novel RD genes. A total of 69 distinct mutations were identified, including 39 novel mutations. Notably, genetic findings in several families were not consistent with the initial clinical diagnosis. Clinical reassessment resulted in refinement of the clinical diagnosis in some of these families and confirmed the broad clinical spectrum associated with mutations in RD genes. 相似文献
867.
868.
869.
The thermophilous chasmophytic vegetation on limestone of the Adriatic Region has been arranged in the endemic order Centaureo-Campanuletalia (class Asplenietea trichomanis). The distribution range of the order covers a large area around the Adriatic Sea – from the south and north east of Italy to Slovenia, Croatia, Bosnia i Hercegovina, Montenegro and Albania. The Centaureo-Campanuletalia or its subordinated syntaxa are quoted in the main syntaxonomic synopses of the Region as well as in technical reports. The critical analysis of the nomenclature of the order, based on the International Code of Phytosociological Nomenclature (ICPN), showed many invalid or incorrect names while it is evident that the usage of correct names in scientific literature is crucial, both for the advances of syntaxonomic knowledge and their application for practical purposes. This paper presents a revision of the nomenclature for the Centaureo-Campanuletalia and related syntaxa in order to stabilize this nomenclature at least at alliance level. As a result, three syntaxa were validated (Centaureo dalmaticae-Campanuletalia pyramidalis, Centaureo cuspidatae-Portenschlagiellion ramosissimae, Inulo verbascifoliae-Centaureetum cuspidatae) and five others were lectotypified. 相似文献
870.
Black rats are of outstanding interest in parasitology and infective disease analysis. We used chromosome paints from both
the mouse(Mus musculus) and the Norway rat(Rattus norvegicus) to characterize the genome of two Black rat subspecies from Italy. Both subspecies have two large metacentrics (n. 1, 4)
not present in the Norway rat (2n = 42).Rattus rattus rattus has a diploid number of 2n = 38, whileRattus rattus frugivorous has two small metacentric “supernumerary” or B chromosomes for a diploid number of 2n = 38 + 2B. The 21 mouse paints gave
38 signals on theR. r. rattus karyotype and 39 signals in theR. r. frugivorous karyotype. The two metacentrics, not present inR. norvegicus, were hybridized by mouse 16/1/17 and mouse 4/10/15. These chromosomes are homologous to: RRA1 = RNO 5/7, and RRA4 = RNO
9/11 and not “4/7” and “11/12” as previously reported. Furthermore, the synteny of Chr 13 of theR. r. frugivorous withR. norvegicus Chr 16 and mouse Chrs 8/14 is not complete, because there is a small pericentromeric insertion of RNO Chr 18 (mouse Chr 18).
If we consider only the two metacentrics, RRA1 and RRA4, the principal differences betweenR. norvegicus andR. rattus, then we can propose the derived synteny of 124 genes in the black rat. A comparison of the Z index between rats and mice
shows an acceleration of genomic evolution among genus, species, and subspecies. The chromosomal differences betweenR. r. rattus xR. r. frugivorous suggest that they may be classified as different species because hybrids would produce 50% unbalanced gametes. 相似文献