全文获取类型
收费全文 | 2363篇 |
免费 | 128篇 |
国内免费 | 3篇 |
出版年
2024年 | 1篇 |
2023年 | 17篇 |
2022年 | 12篇 |
2021年 | 76篇 |
2020年 | 36篇 |
2019年 | 58篇 |
2018年 | 51篇 |
2017年 | 48篇 |
2016年 | 69篇 |
2015年 | 119篇 |
2014年 | 137篇 |
2013年 | 209篇 |
2012年 | 237篇 |
2011年 | 197篇 |
2010年 | 129篇 |
2009年 | 122篇 |
2008年 | 132篇 |
2007年 | 174篇 |
2006年 | 122篇 |
2005年 | 121篇 |
2004年 | 113篇 |
2003年 | 89篇 |
2002年 | 74篇 |
2001年 | 15篇 |
2000年 | 15篇 |
1999年 | 9篇 |
1998年 | 18篇 |
1997年 | 10篇 |
1996年 | 12篇 |
1995年 | 14篇 |
1994年 | 10篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1970年 | 2篇 |
1967年 | 2篇 |
1956年 | 1篇 |
排序方式: 共有2494条查询结果,搜索用时 31 毫秒
941.
The photosystem II activity and energy dissipation was investigated when algal Chlamydomonas reinhardtii genotypes were exposed to dichromate toxicity effect. The exposure during 24 h to dichromate effect of two C. reinhardtii mutants having non-functional xanthophylls cycle, as npq1 zeaxanthin deficient and npq2 zeaxanthin accumulating, induced inhibition of PSII electron transport. After dichromate-induced toxicity, PSII functions
of C. reinhardtii mutants were investigated under different light intensities. To determine dichromate toxicity and light intensity effect
on PSII functional properties we investigated the change of energy dissipation via PSII electron transport, non-photochemical
regulated and non-regulated energy dissipation according to Kramer et al. (Photosynth Res 79:209–218, 2004). We showed the dependency between dichromate toxicity and light-induced photoinhibition in algae deficient in xanthophyll
cycle. When algal mutants missing xanthophylls cycle were exposed to dichromate toxicity and to high light intensity energy
dissipation via non-regulated mechanism takes the most important pathway reaching the value of 80%. Therefore, the mutants
npq1 and npq2 having non-functional xanthophylls cycle were more sensitive to dichromate toxic effects. 相似文献
942.
943.
A human scFv antibody that targets and neutralizes high molecular weight pathogenic amyloid‐β oligomers 下载免费PDF全文
Adriano Sebollela Erika N. Cline Izolda Popova Kevin Luo Xiaoxia Sun Jay Ahn Milena A. Barcelos Vanessa N. Bezerra Natalia M. Lyra e Silva Jason Patel Nathalia R. Pinheiro Lei A. Qin Josette M. Kamel Anthea Weng Nadia DiNunno Adrian M. Bebenek Pauline T. Velasco Kirsten L. Viola Pascale N. Lacor Sergio T. Ferreira William L. Klein 《Journal of neurochemistry》2017,142(6):934-947
944.
Epidermal bladder cells confer salinity stress tolerance in the halophyte quinoa and Atriplex species 总被引:1,自引:0,他引:1 下载免费PDF全文
Ali Kiani‐Pouya Ute Roessner Nirupama S. Jayasinghe Adrian Lutz Thusitha Rupasinghe Nadia Bazihizina Jennifer Bohm Sulaiman Alharbi Rainer Hedrich Sergey Shabala 《Plant, cell & environment》2017,40(9):1900-1915
Epidermal bladder cells (EBCs) have been postulated to assist halophytes in coping with saline environments. However, little direct supporting evidence is available. Here, Chenopodium quinoa plants were grown under saline conditions for 5 weeks. One day prior to salinity treatment, EBCs from all leaves and petioles were gently removed by using a soft cosmetic brush and physiological, ionic and metabolic changes in brushed and non‐brushed leaves were compared. Gentle removal of EBC neither initiated wound metabolism nor affected the physiology and biochemistry of control‐grown plants but did have a pronounced effect on salt‐grown plants, resulting in a salt‐sensitive phenotype. Of 91 detected metabolites, more than half were significantly affected by salinity. Removal of EBC dramatically modified these metabolic changes, with the biggest differences reported for gamma‐aminobutyric acid (GABA), proline, sucrose and inositol, affecting ion transport across cellular membranes (as shown in electrophysiological experiments). This work provides the first direct evidence for a role of EBC in salt tolerance in halophytes and attributes this to (1) a key role of EBC as a salt dump for external sequestration of sodium; (2) improved K+ retention in leaf mesophyll and (3) EBC as a storage space for several metabolites known to modulate plant ionic relations. 相似文献
945.
946.
Delaporte-Quintana Paola Grillo-Puertas Mariana Lovaisa Nadia C. Teixeira Katia R. Rapisarda Viviana A. Pedraza Raúl O. 《Plant and Soil》2017,419(1-2):335-347
Plant and Soil - Gluconacetobacter diazotrophicus (family Acetobacteraceae), is a N2-fixing bacterium with capability of mineral solubilization through organic acid production. The aim of this work... 相似文献
947.
Principal response curves analysis (PRC) is widely applied to experimental multivariate longitudinal data for the study of time-dependent treatment effects on the multiple outcomes or response variables (RVs). Often, not all of the RVs included in such a study are affected by the treatment and RV-selection can be used to identify those RVs and so give a better estimate of the principal response. We propose four backward selection approaches, based on permutation testing, that differ in whether coefficient size is used or not in ranking the RVs. These methods are expected to give a more robust result than the use of a straightforward cut-off value for coefficient size. Performance of all methods is demonstrated in a simulation study using realistic data. The permutation testing approach that uses information on coefficient size of RVs speeds up the algorithm without affecting its performance. This most successful permutation testing approach removes roughly 95 % of the RVs that are unaffected by the treatment irrespective of the characteristics of the data set and, in the simulations, correctly identifies up to 97 % of RVs affected by the treatment. 相似文献
948.
Junming Shi Zhengyuan Su Zhaojun Fan Jun Wang Siqing Liu Bo Zhang Hongping Wei Shoukat Jehan Nadia Jamil Shu Shen Fei Deng 《中国病毒学》2017,32(6):520-532
Chikungunya virus (CHIKV) is a mosquito-borne virus that causes epidemics widely in the world especially in the tropical and subtropical regions. Phylogenetic analysis has found that the CHIKV lineages were associated with the spatial and temporal distributions, which were related to the virus adaption to the major mosquito species and their distributions. In this study, we reported the complete genome sequences of eight CHIKV isolates from the outbreak in Pakistan last year. Then we reviewed the evolutionary history using extensive phylogenetic analysis, analyzed lineage-specific substitutions in viral proteins, and characterized the spreading pathway of CHIKV strains including the Pakistani strains. The results showed that the Pakistani stains belonged to the ECSA.IOL sub-lineage and derived from India. The genetic properties of the Pakistani strains including the adaptive substitution to vectors were further characterized, and the potential risks from the occurrence of CHIKV infection in Pakistan were discussed. These results provided better understanding of CHIKV evolution and transmission in the world and revealed the possible origination of the CHIKV outbreak and epidemic in Pakistan, which would promote the disease prevention and control in the identified countries and territories with the history of CHIKV infections as well as new regions with potential risk of CHIKV outbreaks. 相似文献
949.
Aracelys López-Castilla Bruno Vitorge Léa Khoury Nelly Morellet Olivera Francetic Nadia Izadi-Pruneyre 《Biomolecular NMR assignments》2017,11(2):155-158
Bacteria use complex transporters to secrete functionally relevant proteins to the extracellular medium. The type 2 secretion system (T2SS) translocates folded proteins involved in bacterial nutrient acquisition, virulence and adaptation. The T2SS pseudopilus is a periplasmic filament, assembled by the polymerization of PulG subunits, the major pseudopilin. Pseudopilin proteins have a conserved N-terminal hydrophobic segment followed by a more variable C-terminal periplasmic and globular domain. To better understand the mechanism of assembly and function of the T2SS, we have been studying the structure and dynamics of PulG by NMR, as well as its interaction with other components of the secretion machinery. As a first step on this study, here we reported the chemical shift assignments of PulG C-terminal domain and its secondary structure prediction based on NMR data. 相似文献
950.
Saoussen Trabelsi Imen Chabchoub Iadh Ksira Nadhir Karmeni Nadia Mama Samia Kanoun Anna Burford Alexa Jury Alan Mackay Sergey Popov Noureddine Bouaouina Slim Ben Ahmed Moncef Mokni Kalthoum Tlili Hedi Krifa Mohamed Tahar Yacoubi Chris Jones Ali Saad Dorra H’mida Ben Brahim 《Molecular neurobiology》2017,54(4):2381-2394
It has become increasingly evident that morphologically similar gliomas may have distinct clinical phenotypes arising from diverse genetic signatures. To date, glial tumours from the Tunisian population have not been investigated. To address this, we correlated the clinico-pathology with molecular data of 110 gliomas by a combination of HM450K array, MLPA and TMA-IHC. PTEN loss and EGFR amplification were distributed in different glioma histological groups. However, 1p19q co-deletion and KIAA1549:BRAF fusion were, respectively, restricted to Oligodendroglioma and Pilocytic Astrocytoma. CDKN2A loss and EGFR overexpression were more common within high-grade gliomas. Furthermore, survival statistical correlations led us to identify Glioblastoma (GB) prognosis subtypes. In fact, significant lower overall survival (OS) was detected within GB that overexpressed EGFR and Cox2. In addition, IDH1R132H mutation seemed to provide a markedly survival advantage. Interestingly, the association of IDHR132H mutation and EGFR normal status, as well as the association of differentiation markers, defined GB subtypes with good prognosis. By contrast, poor survival GB subtypes were defined by the combination of PTEN loss with PDGFRa expression and/or EGFR amplification. Additionally, GB presenting p53-negative staining associated with CDKN2A loss or p21 positivity represented a subtype with short survival. Thus, distinct molecular subtypes with individualised prognosis were identified. Interestingly, we found a unique histone mutation in a poor survival young adult GB case. This tumour exceptionally associated the H3F3A G34R mutation and MYCN amplification as well as 1p36 loss and 10q loss. Furthermore, by exhibiting a remarkable methylation profile, it emphasised the oncogenic power of G34R mutation connecting gliomagenesis and chromatin regulation. 相似文献