全文获取类型
收费全文 | 2837篇 |
免费 | 255篇 |
专业分类
3092篇 |
出版年
2024年 | 3篇 |
2023年 | 30篇 |
2022年 | 63篇 |
2021年 | 88篇 |
2020年 | 65篇 |
2019年 | 63篇 |
2018年 | 85篇 |
2017年 | 61篇 |
2016年 | 116篇 |
2015年 | 193篇 |
2014年 | 195篇 |
2013年 | 259篇 |
2012年 | 305篇 |
2011年 | 242篇 |
2010年 | 178篇 |
2009年 | 158篇 |
2008年 | 154篇 |
2007年 | 160篇 |
2006年 | 134篇 |
2005年 | 100篇 |
2004年 | 85篇 |
2003年 | 79篇 |
2002年 | 47篇 |
2001年 | 15篇 |
2000年 | 17篇 |
1999年 | 15篇 |
1998年 | 6篇 |
1997年 | 10篇 |
1996年 | 7篇 |
1995年 | 3篇 |
1993年 | 6篇 |
1992年 | 20篇 |
1991年 | 6篇 |
1990年 | 11篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1976年 | 4篇 |
1975年 | 9篇 |
1971年 | 3篇 |
1937年 | 3篇 |
排序方式: 共有3092条查询结果,搜索用时 15 毫秒
51.
Sévajol M Reiser JB Chouquet A Pérard J Ayala I Gans P Kleman JP Housset D 《Biochimie》2012,94(3):823-828
The eukaryotic Engulfment and CellMotility (ELMO) proteins form an evolutionary conserved family of key regulators which play a central role in Rho-dependent biological processes such as engulfment and cell motility/migration. ELMO proteins interact with a subset of Downstream of Crk (DOCK) family members, a new type of guanine exchange factors (GEF) for Rac and cdc42 GTPases. The physiological function of DOCK is to facilitate actin remodeling, a process which occurs only in presence of ELMO. Several studies have determined that the last 200 C-terminal residues of ELMO1 and the first 180 N-terminal residues of DOCK180 are responsible for the ELMO-DOCK interaction. However, the precise role of the different domains and motifs identified in these regions has remained elusive. Divergent functional, biochemical and structural data have been reported regarding the contribution of the C-terminal end of ELMO, comprising its polyproline motif, and of the DOCK SH3 domain. In the present study, we have investigated the contribution of the C-terminal end of ELMO1 to the interaction between ELMO1 and the SH3 domain of DOCK180 using nuclear magnetic resonance spectroscopy and surface plasmon resonance. Our data presented here demonstrate the ability of the SH3 domain of DOCK180 to interact with ELMO1, regardless of the presence of the polyproline-containing C-terminal end. However, the presence of the polyproline region leads to a significant increase in the half-life of the ELMO1-DOCK180 complex, along with a moderate increase on the affinity. 相似文献
52.
Yan Ropert-Coudert Akiko Kato Julien Baudat Charles-André Bost Yvon Le Maho Yasuhiko Naito 《Polar Biology》2001,24(6):467-470
Data on the swim speed, dive depth and feeding rates of three Adélie penguins (Pygoscelis adeliae) foraging in summer 1998/1999 in Adélie Land, Antarctica were collected using dorsally-mounted loggers, in tandem with oesophageal temperature sensors. Swim speed could be integrated, together with the rate of change of depth, to determine dive and return-to-surface angles. Overall, birds increased rates of change of depth during commuting phases so that dive angles were steeper in dives terminating at greater depths. Angles of descent and ascent during feeding dives were greater than during non-feeding dives. Variation in the descent angle over time of particular dives was generally less than 10°, but the angles of the ascent phases varied more widely. The importance of selecting the optimum descent and ascent angles with respect to prey exploitation, oxygen stores and time gained in the feeding area over the course of a dive by diving at a steeper angle is discussed. 相似文献
53.
Monitoring and classification of PAH toxicity using an immobilized bioluminescent bacteria 总被引:6,自引:0,他引:6
An immobilized recombinant bioluminescent Escherichia coli strain, harboring a lac::luxCDABE fused plasmid, which shows lower bioluminescence levels when cellular metabolism is inhibited, was used to monitor the cellular toxicity of polycyclic aromatic hydrocarbons (PAHs). PAHs, classified as pericondensed (PCPAHs) or catacondensed (CCPAHs) according to their molecular structures, were differentiable according to the response of this biosensor. Only CCPAHs were found to cause cellular toxicity, resulting in a dose-dependent decrease in the bioluminescent output. The induction of cellular toxicity by CCPAHs and PCPAHs was compared with acute toxicity predictions obtained using the quantitative structure-activity relationship (QSAR) model. A good relationship was obtained between the toxicities determined with the bioluminescent response of the immobilized bacterium GC2 and the QSAR model. It was also found that the present study offers a new method of predicting the cellular toxicities of CCPAHs or PCPAHs using this biosensor. 相似文献
54.
Zhao Xuan Gael Barthet Junichi Shioi Jindong Xu Anastasios Georgakopoulos Julien Bruban Nikolaos K. Robakis 《The Journal of biological chemistry》2013,288(42):30495-30501
Abnormally high concentrations of extracellular glutamate in the brain may cause neuronal damage via excitotoxicity. Thus, tight regulation of glutamate release is critical to neuronal function and survival. Excitotoxicity is caused mainly by overactivation of the extrasynaptic NMDA receptor (NMDAR) and results in specific cellular changes, including calcium-induced activation of calpain proteases. Here, we report that presenilin-1 (PS1) null mouse cortical neuronal cultures have increased amounts of calpain-dependent spectrin breakdown products (SBDPs) compared with WT cultures. NMDAR antagonists blocked accumulation of SBDPs, suggesting abnormal activation of this receptor in PS1 null cultures. Importantly, an increase in SBDPs was detected in cultures of at least 7 days in vitro but not in younger cultures. Conditioned medium from PS1 null neuronal cultures at 8 days in vitro contained higher levels of glutamate than medium from WT cultures and stimulated production of SBDPs when added to WT cultures. Use of glutamate reuptake inhibitors indicated that accumulation of this neurotransmitter in the media of PS1 null cultures was due to increased rates of release. PS1 null neurons showed decreased cell surface expression and phosphorylation of the GluN2B subunit of NMDAR, indicating decreased amounts of extrasynaptic NMDAR in the absence of PS1. Inhibition of γ-secretase activity in WT neurons caused changes similar to those observed in PS1 null neurons. Together, these data indicate that the PS1/γ-secretase system regulates release of glutamate, tyrosine phosphorylation, and surface expression of GluN2B-containing NMDARs. 相似文献
55.
Chemical Diversity and Antimicrobial Activity of Volatile Compounds from Zanthoxylum zanthoxyloides Lam. according to Compound Classes,Plant Organs and Senegalese Sample Locations 下载免费PDF全文
Yoro Tine Abdoulaye Diop William Diatta Jean‐Marie Desjobert Cheikh Saad Bouh Boye Jean Costa Alassane Wélé Julien Paolini 《化学与生物多样性》2017,14(1)
The chemical diversity of Zanthoxylum zanthoxyloides growing wild in Senegal was studied according to volatile compound classes, plant organs and sample locations. The composition of fruit essential oil was investigated using an original targeted approach based on the combination of gas chromatography (GC) and liquid chromatography (LC) both coupled with mass spectrometry (MS). The volatile composition of Z. zanthoxyloides fruits exhibited relative high amounts of hydrocarbon monoterpenes (24.3 – 55.8%) and non‐terpenic oxygenated compounds (34.5 – 63.1%). The main components were (E)‐β‐ocimene (12.1 – 39%), octyl acetate (11.6 – 21.8%) and decanol (9.7 – 15.4%). The GC and GC/MS profiling of fruit essential oils showed a chemical variability according to geographical locations of plant material. The LC/MS/MS analysis of fruit oils allowed the detection of seven coumarins in trace content. The chemical composition of fruit essential oils was compared with volatile fractions of leaves and barks (root and trunk) from the same plant station. Hexadecanoic acid, germacrene D and decanal were identified as the major constituents of leaves whereas the barks (root and trunk) were dominated by pellitorine (85.8% and 57%, respectively), an atypic linear compound with amide group. The fruit essential oil exhibited interesting antimicrobial activities against Staphylococcus aureus and Candida albicans, particularly the alcohol fraction of the oil. 相似文献
56.
Julien Cucherousset Line E. Sundt-Hansen Mathieu Buoro Libor Závorka Rémy Lassus Knut A. E. Bækkelie Ian A. Fleming Björn Thrandur Björnsson Jörgen I. Johnsson Kjetil Hindar 《Journal of fish biology》2021,99(6):1978-1989
Use of fast-growing domesticated and/or genetically modified strains of fish is becoming increasingly common in aquaculture, increasing the likelihood of deliberate or accidental introductions into the wild. To date, their ecological impacts on ecosystems remain to be quantified. Here, using a controlled phenotype manipulation by implanting growth hormone in juvenile Atlantic salmon (Salmo salar), we found that growth-enhanced fish display changes in several phenotypic traits known to be important for ecosystem functioning, such as habitat use, morphology and excretion rate. Furthermore, these phenotypic changes were associated with significant impacts on the invertebrate community and key stream ecosystem functions such as primary production and leaf-litter decomposition. These findings provide novel evidence that introductions of growth-enhanced fish into the wild can affect the functioning of natural ecosystems and represent a form of intraspecific invasion. Consequently, environmental impact assessments of growth-enhanced organisms need to explicitly consider ecosystem-level effects. 相似文献
57.
58.
59.
Aude Tixier Eric Badel Jerome Franchel Wassim Lakhal Nathalie Leblanc‐Fournier Bruno Moulia Jean‐Louis Julien 《Physiologia plantarum》2014,150(2):225-237
Inter‐organ communication is essential for plants to coordinate development and acclimate to mechanical environmental fluctuations. The aim of this study was to investigate long‐distance signaling in trees. We compared on young poplars the short‐term effects of local flame wounding and of local stem bending for two distal responses: (1) stem primary growth and (2) the expression of mechanoresponsive genes in stem apices. We developed a non‐contact measurement method based on the analysis of apex images in order to measure the primary growth of poplars. The results showed a phased stem elongation with alternating nocturnal circumnutation phases and diurnal growth arrest phases in Populus tremula × alba clone INRA 717‐1B4. We applied real‐time polymerase chain reaction (RT‐PCR) amplifications in order to evaluate the PtaZFP2, PtaTCH2, PtaTCH4, PtaACS6 and PtaJAZ5 expressions. The flame wounding inhibited primary growth and triggered remote molecular responses. Flame wounding induced significant changes in stem elongation phases, coupled with inhibition of circumnutation. However, the circadian rhythm of phases remained unaltered and the treated plants were always phased with control plants during the days following the stress. For bent plants, the stimulated region of the stem showed an increased PtaJAZ5 expression, suggesting the jasmonates may be involved in local responses to bending. No significant remote responses to bending were observed. 相似文献
60.
Thibaut Capblancq Xavier Morin Maya Gueguen Julien Renaud Stphane Lobreaux Eric Bazin 《Journal of evolutionary biology》2020,33(6):783-796
Local adaptation patterns have been found in many plants and animals, highlighting the genetic heterogeneity of species along their range of distribution. In the next decades, global warming is predicted to induce a change in the selective pressures that drive this adaptive variation, forcing a reshuffling of the underlying adaptive allele distributions. For species with low dispersion capacity and long generation time such as trees, the rapidity of the change could impede the migration of beneficial alleles and lower their capacity to track the changing environment. Identifying the main selective pressures driving the adaptive genetic variation is thus necessary when investigating species capacity to respond to global warming. In this study, we investigate the adaptive landscape of Fagus sylvatica along a gradient of populations in the French Alps. Using a double‐digest restriction‐site‐associated DNA (ddRAD) sequencing approach, we identified 7,000 SNPs from 570 individuals across 36 different sites. A redundancy analysis (RDA)‐derived method allowed us to identify several SNPs that were strongly associated with climatic gradients; moreover, we defined the primary selective gradients along the natural populations of F. sylvatica in the Alps. Strong effects of elevation and humidity, which contrast north‐western and south‐eastern site, were found and were believed to be important drivers of genetic adaptation. Finally, simulations of future genetic landscapes that used these findings allowed identifying populations at risk for F. sylvatica in the Alps, which could be helpful for future management plans. 相似文献