全文获取类型
收费全文 | 6296篇 |
免费 | 486篇 |
国内免费 | 2篇 |
专业分类
6784篇 |
出版年
2023年 | 31篇 |
2022年 | 92篇 |
2021年 | 157篇 |
2020年 | 106篇 |
2019年 | 126篇 |
2018年 | 159篇 |
2017年 | 140篇 |
2016年 | 224篇 |
2015年 | 329篇 |
2014年 | 328篇 |
2013年 | 554篇 |
2012年 | 562篇 |
2011年 | 498篇 |
2010年 | 332篇 |
2009年 | 254篇 |
2008年 | 400篇 |
2007年 | 395篇 |
2006年 | 362篇 |
2005年 | 267篇 |
2004年 | 276篇 |
2003年 | 262篇 |
2002年 | 236篇 |
2001年 | 48篇 |
2000年 | 34篇 |
1999年 | 55篇 |
1998年 | 57篇 |
1997年 | 51篇 |
1996年 | 45篇 |
1995年 | 29篇 |
1994年 | 40篇 |
1993年 | 42篇 |
1992年 | 27篇 |
1991年 | 21篇 |
1990年 | 22篇 |
1989年 | 13篇 |
1988年 | 14篇 |
1987年 | 16篇 |
1986年 | 12篇 |
1985年 | 10篇 |
1984年 | 18篇 |
1983年 | 15篇 |
1982年 | 18篇 |
1981年 | 17篇 |
1980年 | 7篇 |
1978年 | 13篇 |
1977年 | 9篇 |
1976年 | 6篇 |
1974年 | 7篇 |
1973年 | 7篇 |
1972年 | 6篇 |
排序方式: 共有6784条查询结果,搜索用时 15 毫秒
61.
62.
Stefania Raimondo Ornella Urzì Serena Meraviglia Marta Di Simone Anna Maria Corsale Nima Rabienezhad Ganji Antonio Palumbo Piccionello Giulia Polito Elena Lo Presti Francesco Dieli Alice Conigliaro Riccardo Alessandro 《Journal of cellular and molecular medicine》2022,26(15):4195
Chronic inflammation is associated with the occurrence of several diseases. However, the side effects of anti‐inflammatory drugs prompt the identification of new therapeutic strategies. Plant‐derived extracellular vesicles (PDEVs) are gaining increasing interest in the scientific community for their biological properties. We isolated PDEVs from the juice of Citrus limon L. (LEVs) and characterized their flavonoid, limonoid and lipid contents through reversed‐phase high‐performance liquid chromatography coupled to electrospray ionization quadrupole time‐of‐flight mass spectrometry (RP‐HPLC–ESI‐Q‐TOF‐MS). To investigate whether LEVs have a protective role on the inflammatory process, murine and primary human macrophages were pre‐treated with LEVs for 24 h and then were stimulated with lipopolysaccharide (LPS). We found that pre‐treatment with LEVs decreased gene and protein expression of pro‐inflammatory cytokines, such as IL‐6, IL1‐β and TNF‐α, and reduced the nuclear translocation and phosphorylation of NF‐κB in LPS‐stimulated murine macrophages. The inhibition of NF‐κB activation was associated with the reduction in ERK1‐2 phosphorylation. Furthermore, the ability of LEVs to decrease pro‐inflammatory cytokines and increase anti‐inflammatory molecules was confirmed ex vivo in human primary T lymphocytes. In conclusion, we demonstrated that LEVs exert anti‐inflammatory effects both in vitro and ex vivo by inhibiting the ERK1‐2/NF‐κB signalling pathway. 相似文献
63.
Jens Kieckbusch Louise M. Gaynor Francesco Colucci 《Journal of visualized experiments : JoVE》2015,(106)
The placenta mediates the exchange of factors such as gases and nutrients between mother and fetus and has specific demands for supply of blood from the maternal circulation. The maternal uterine vasculature needs to adapt to this temporary demand and the success of this arterial remodeling process has implications for fetal growth. Cells of the maternal immune system, especially natural killer (NK) cells, play a critical role in this process. Here we describe a method to assess the degree of remodeling of maternal spiral arteries during mouse pregnancy. Hematoxylin and eosin-stained tissue sections are scanned and the size of the vessels analysed. As a complementary validation method, we also present a qualitative assessment for the success of the remodeling process by immunohistochemical detection of smooth muscle actin (SMA), which normally disappears from within the arterial vascular media at mid-gestation. Together, these methods enable determination of an important parameter of the pregnancy phenotype. These results can be combined with other endpoints of mouse pregnancy to provide insight into the mechanisms underlying pregnancy-related complications. 相似文献
64.
The human ryanodine receptor gene: Its mapping to 19q13.1, placement in a chromosome 19 linkage group, and exclusion as the gene causing myotonic dystrophy 总被引:9,自引:1,他引:9 下载免费PDF全文
Alex E. MacKenzie Robert G. Korneluk Francesco Zorzato Junichi Fujii Michael Phillips David Iles B Wieringa Suzanne Leblond Jane Bailly Huntington F. Willard Catherine Duff Ronald G. Worton David H. MacLennan 《American journal of human genetics》1990,46(6):1082-1089
The recent cloning of cDNA encoding the Ca++ release channel (ryanodine receptor) of human sarcoplasmic reticulum has enabled us to use somatic cell hybrids to localize the ryanodine receptor gene (RYR) to the proximal long arm of human chromosome 19. Studies with additional hybrids containing deletions or translocations in chromosome 19 enabled us to localize RYR to 19q13.1 in a region distal to GPI/MAG and proximal to D19S18/DNF11. On the basis that the myotonic dystrophy (DM) locus maps near this region and that myotonia could result from a defect in the ryanodine receptor, we examined the linkage between the DM locus and RYR. Our results, showing several DM-RYR recombinants, rule out an RYR defect as the cause of DM. However, localization of RYR to a region of human chromosome 19 which is syntenic to an area of pig chromosome 6 containing the HAL gene responsible for porcine malignant hyperthermia supports the candidacy of RYR for this disorder. 相似文献
65.
Sara Bruschini Simona di Martino Maria Elena Pisanu Luigi Fattore Claudia De Vitis Valentina Laquintana Simonetta Buglioni Eugenio Tabbì Andrea Cerri Paolo Visca Gabriele Alessandrini Francesco Facciolo Christian Napoli Marcella Trombetta Antonio Santoro Anna Crescenzi Gennaro Ciliberto Rita Mancini 《Journal of cellular physiology》2020,235(3):1877-1887
66.
Esposito Francesco Memoli Valeria Panico Speranza Claudia Trifuoggi Marco Di Natale Gabriella Maisto Giulia 《Plant and Soil》2019,436(1-2):517-526
Plant and Soil - The aims of this research were: i) to compare Cr, Cu, Ni and Pb concentrations in Quercus ilex L. leaves collected at urban/industrial and urban areas; ii) to investigate the main... 相似文献
67.
Mauro C Vito P Mellone S Pacifico F Chariot A Formisano S Leonardi A 《Biochemical and biophysical research communications》2003,309(1):84-90
Nuclear factor kappaB (NF-kappaB) plays a pivotal role in numerous cellular processes, including stress response, inflammation, and protection from apoptosis. Therefore, the activity of NF-kappaB needs to be tightly regulated. We have previously identified a novel gene, named CIKS (connection to IkappaB-kinase and SAPK), able to bind the regulatory sub-unit NEMO/IKKgamma and to activate NF-kappaB. Here, we demonstrate that CIKS forms homo-oligomers, interacts with NEMO/IKKgamma, and is recruited to the IKK-complex upon cell stimulation. In addition, we identified the regions of CIKS responsible for these functions. We found that the ability of CIKS to oligomerize, and to be recruited to the IKK-complex is not sufficient to activate the NF-kappaB. In fact, a deletion mutant of CIKS able to oligomerize, to interact with NEMO/IKKgamma, and to be recruited to the IKK-complex does not activate NF-kappaB, suggesting that CIKS needs a second level of regulation to efficiently activate NF-kappaB. 相似文献
68.
Deciphering the molecular machinery of stem cells: a look at the neoblast gene expression profile 下载免费PDF全文
Rossi L Salvetti A Marincola FM Lena A Deri P Mannini L Batistoni R Wang E Gremigni V 《Genome biology》2007,8(4):R62
Background
Mammalian stem cells are difficult to access experimentally; model systems that can regenerate offer an alternative way to characterize stem cell related genes. Planarian regeneration depends on adult pluripotent stem cells - the neoblasts. These cells can be selectively destroyed using X-rays, enabling comparison of organisms lacking stem cells with wild-type worms. 相似文献69.
Contribution of the dimeric state to the thermal stability of the flavoprotein D-amino acid oxidase 下载免费PDF全文
Pollegioni L Iametti S Fessas D Caldinelli L Piubelli L Barbiroli A Pilone MS Bonomi F 《Protein science : a publication of the Protein Society》2003,12(5):1018-1029
The flavoenzyme DAAO from Rhodotorula gracilis, a structural paradigm of the glutathione-reductase family of flavoproteins, is a stable homodimer with a flavin adenine dinucleotide (FAD) molecule tightly bound to each 40-kD subunit. In this work, the thermal unfolding of dimeric DAAO was compared with that of two monomeric forms of the same protein: a Deltaloop mutant, in which 14 residues belonging to a loop connecting strands betaF5-betaF6 have been deleted, and a monomer obtained by treating the native holoenzyme with 0.5 M NH(4)SCN. Thiocyanate specifically and reversibly affects monomer association in wild-type DAAO by acting on hydrophobic residues and on ionic pairs between the betaF5-betaF6 loop of one monomer and the alphaI3' and alphaI3" helices of the symmetry-related monomer. By using circular dichroism spectroscopy, protein and flavin fluorescence, activity assays, and DSC, we demonstrated that thermal unfolding involves (in order of increasing temperatures) loss of tertiary structure, followed by loss of some elements of secondary structure, and by general unfolding of the protein structure that was concomitant to FAD release. Temperature stability of wild-type DAAO is related to the presence of a dimeric structure that affects the stability of independent structural domains. The monomeric Deltaloop mutant is thermodynamically less stable than dimeric wild-type DAAO (with melting temperatures (T(m)s) of 48 degrees C and 54 degrees C, respectively). The absence of complications ensuing from association equilibria in the mutant Deltaloop DAAO allowed identification of two energetic domains: a low-temperature energetic domain related to unfolding of tertiary structure, and a high-temperature energetic domain related to loss of secondary structure elements and to flavin release. 相似文献
70.
Schlesinger J Koezle I Bergmann R Tamburini S Bolzati C Tisato F Noll B Klussmann S Vonhoff S Wuest F Pietzsch HJ Steinbach J 《Bioconjugate chemistry》2008,19(4):928-939
A mirror-image oligonucleotide (L-RNA) was radiolabeled with the positron emitting radionuclide (86)Y (t(1/2) = 14.7 h) via the bifunctional chelator approach. DOTA-modification of the L-RNA (sequence: 5'-aminohexyl UGA CUG ACU GAC-3'; MW 3975) was performed using (S)-p-SCN-Bn-DOTA. (86)Y radiolabeling of the DOTA-L-RNA produced more than one species as evidenced by HPLC radiometric detection. For the identification of the (86)Y-labeled L-RNA, the structural analogue nonradioactive precursor [Y((S)-p-NH2-Bn-DOTA)](-) was synthesized. Two coordination isomers were separated via HPLC adopting the square antiprismatic (SAP) and the twisted square antiprismatic (TSAP) geometry, respectively. Their stereochemical configuration in the solution state was assessed by NMR and circular dichroism spectroscopy. Both [Y((S)-p-NH2-Bn-DOTA)](-) isomers were converted into isothiocyanate derivatives [Y((S)-p-SCN-Bn-DOTA)](-) and conjugated to the L-RNA. The identity of the [(86)Y-DOTA]-L-RNA species was finally established by comparison of the radiometric ((86)Y) and UV-visible chromatographic profiles. Biodistribution studies in Wistar rats showed minor changes in the biodistribution profile of the [(86)Y((S)-p-NH2-Bn-DOTA)](-) complex isomers, while no significant differences were observed for the [(86)Y-DOTA]-L-RNA isomers. High renal excretions were found for the [(86)Y((S)-p-NH 2-Bn-DOTA)](-) complex isomers as well as for the L-RNA isomers. 相似文献