全文获取类型
收费全文 | 508篇 |
免费 | 58篇 |
专业分类
566篇 |
出版年
2022年 | 5篇 |
2021年 | 15篇 |
2020年 | 9篇 |
2019年 | 9篇 |
2018年 | 11篇 |
2017年 | 9篇 |
2016年 | 18篇 |
2015年 | 39篇 |
2014年 | 35篇 |
2013年 | 25篇 |
2012年 | 48篇 |
2011年 | 38篇 |
2010年 | 23篇 |
2009年 | 23篇 |
2008年 | 31篇 |
2007年 | 22篇 |
2006年 | 38篇 |
2005年 | 23篇 |
2004年 | 31篇 |
2003年 | 20篇 |
2002年 | 19篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 4篇 |
1998年 | 11篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 6篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1968年 | 3篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1942年 | 1篇 |
排序方式: 共有566条查询结果,搜索用时 9 毫秒
1.
Mandy L. Roberts-Crowley Tora Mitra-Ganguli Liwang Liu Ann R. Rittenhouse 《Cell calcium》2009,45(6):589-601
Great skepticism has surrounded the question of whether modulation of voltage-gated Ca2+ channels (VGCCs) by the polyunsaturated free fatty acid arachidonic acid (AA) has any physiological basis. Here we synthesize findings from studies of both native and recombinant channels where micromolar concentrations of AA consistently inhibit both native and recombinant activity by stabilizing VGCCs in one or more closed states. Structural requirements for these inhibitory actions include a chain length of at least 18 carbons and multiple double bonds located near the fatty acid's carboxy terminus. Acting at a second site, AA increases the rate of VGCC activation kinetics, and in CaV2.2 channels, increases current amplitude. We present evidence that phosphatidylinositol 4,5-bisphosphate (PIP2), a palmitoylated accessory subunit (β2a) of VGCCs and AA appear to have overlapping sites of action giving rise to complex channel behavior. Their actions converge in a physiologically relevant manner during muscarinic modulation of VGCCs. We speculate that M1 muscarinic receptors may stimulate multiple lipases to break down the PIP2 associated with VGCCs and leave PIP2's freed fatty acid tails bound to the channels to confer modulation. This unexpectedly simple scheme gives rise to unanticipated predictions and redirects thinking about lipid regulation of VGCCs. 相似文献
2.
3.
Joe Carver Domingos Ng Michelle Zhou Peggy Ko Dejin Zhan Mandy Yim David Shaw Brad Snedecor Michael W. Laird Steven Lang Amy Shen Zhilan Hu 《Biotechnology progress》2020,36(4):e2967
Historically, therapeutic protein production in Chinese hamster ovary (CHO) cells has been accomplished by random integration (RI) of expression plasmids into the host cell genome. More recently, the development of targeted integration (TI) host cells has allowed for recombination of plasmid DNA into a predetermined genomic locus, eliminating one contributor to clone-to-clone variability. In this study, a TI host capable of simultaneously integrating two plasmids at the same genomic site was used to assess the effect of antibody heavy chain and light chain gene dosage on antibody productivity. Our results showed that increasing antibody gene copy number can increase specific productivity, but with diminishing returns as more antibody genes are added to the same TI locus. Random integration of additional antibody DNA copies in to a targeted integration cell line showed a further increase in specific productivity, suggesting that targeting additional genomic sites for gene integration may be beneficial. Additionally, the position of antibody genes in the two plasmids was observed to have a strong effect on antibody expression level. These findings shed light on vector design to maximize production of conventional antibodies or tune expression for proper assembly of complex or bispecific antibodies in a TI system. 相似文献
4.
5.
6.
Matthieu Legrand Benedetta De Berardinis Hanna K. Gaggin Laura Magrini Arianna Belcher Benedetta Zancla Alexandra Femia Mandy Simon Shweta Motiwala Rasika Sambhare Salvatore Di Somma Alexandre Mebazaa Vishal S. Vaidya James L. Januzzi Jr from the Global Research on Acute Conditions Team 《PloS one》2014,9(11)
Objective
The objective of the study was to assess urinary biomarkers of renal injury for their individual or collective ability to predict Worsening renal function (WRF) in patients with acutely decompensated heart failure (ADHF).Methods
In a prospective, blinded international study, 87 emergency department (ED) patients with ADHF were evaluated with biomarkers of cardiac stretch (B type natriuretic peptide [BNP] and its amino terminal equivalent [NT-proBNP], ST2), biomarkers of renal function (creatinine, estimated glomerular filtration rate [eGFR]) and biomarkers of renal injury (plasma neutrophil gelatinase associated lipocalin [pNGAL], urine kidney injury molecule-1 [KIM-1], urine N-acetyl-beta-D-glucosaminidase [NAG], urine Cystatin C, urine fibrinogen). The primary endpoint was WRF.Results
26% developed WRF; baseline characteristics of subjects who developed WRF were generally comparable to those who did not. Biomarkers of renal function and urine biomarkers of renal injury were not correlated, while urine biomarkers of renal injury correlated between each other. Biomarker concentrations were similar between patients with and without WRF except for baseline BNP. Although plasma NGAL was associated with the combined endpoint, none of the biomarker showed predictive accuracy for WRF.Conclusions
In ED patients with ADHF, urine biomarkers of renal injury did not predict WRF. Our data suggest that a weak association exists between renal dysfunction and renal injury in this setting (Clinicaltrials.gov NCT#0150153). 相似文献7.
We show that the MutY protein competes with the MutS-dependent mismatch repair system to process at least some A. C mispairs in vivo, converting them to G. C pairs. In the presence of an increased dCTP pool resulting from the loss of nucleotide diphosphate kinase, the frequency of A. T-->G. C transitions at a hot spot in the rpoB gene is 30-fold lower in a MutY-deficient derivative than in the wild type. 相似文献
8.
Asthenozoospermia in mice with targeted deletion of the sperm mitochondrion-associated cysteine-rich protein (Smcp) gene 下载免费PDF全文
Nayernia K Adham IM Burkhardt-Göttges E Neesen J Rieche M Wolf S Sancken U Kleene K Engel W 《Molecular and cellular biology》2002,22(9):3046-3052
The sperm mitochondria-associated cysteine-rich protein (SMCP) is a cysteine- and proline-rich structural protein that is closely associated with the keratinous capsules of sperm mitochondria in the mitochondrial sheath surrounding the outer dense fibers and axoneme. To investigate the function of SMCP, we generated mice with a targeted disruption of the gene Smcp by homologous recombination. Homozygous mutant males on a mixed genetic background (C57BL/6J x 129/Sv) are fully fertile, while they are infertile on the 129/Sv background, although spermatogenesis and mating are normal. Homozygous Smcp(-/-) female mice are fertile on both genetic backgrounds. Electron microscopical examination demonstrated normal structures of sperm head, mitochondria, and tail. In vivo experiments with sperm of Smcp(-/-) 129/Sv mice revealed that the migration of spermatozoa from the uterus into the oviduct is reduced. This result is supported by the observation that sperm motility as determined by the computer-assisted semen analysis system (CASA) is significantly affected as compared to wild-type spermatozoa. In vitro fertilization assays showed that Smcp-deficient spermatozoa are able to bind to the oocyte but that the number of fertilized eggs is reduced by more than threefold relative to the wild-type control. However, removal of the zona pellucida resulted in an unaffected sperm-egg fusion which was monitored by the presence of pronuclei and generation of blastocyts. These results indicate that the infertility of the male Smcp(-/-) mice on the 129/Sv background is due to reduced motility of the spermatozoa and decreased capability of the spermatozoa to penetrate oocytes. 相似文献
9.
10.
Timo Frensing Antje Pflugmacher Mandy Bachmann Britta Peschel Udo Reichl 《Applied microbiology and biotechnology》2014,98(21):8999-9008
During the replication of influenza viruses, defective interfering particles (DIPs) can be generated. These are noninfectious deletion mutants that require coinfection with a wild-type virus but interfere with its helper virus replication. Consequently, coinfected cells mainly produce DIPs. Little is known about how such noninfectious virus particles affect the virus yield of cell culture-based influenza vaccine production. We compared infections of Madin-Darby canine kidney cells with two seed virus preparations of the influenza virus strain A/Puerto Rico/8/34 that contain different amounts of DIPs. A combination of conventional RT-PCR, RT-qPCR, and flow cytometry revealed that DI genomes indeed strongly accumulate in coinfected cells and impede the viral RNA synthesis. Additionally, cells infected at the higher DIP concentration showed a stronger antiviral response characterized by increased interferon-β expression and apoptosis induction. Furthermore, in the presence of DIPs, a significant fraction of cells did not show any productive accumulation of viral proteins at all. Together, these effects of DIPs significantly reduce the virus yield. Therefore, the accumulation of DIPs should be avoided during influenza vaccine production which can be achieved by quality controls of working seed viruses based on conventional RT-PCR. The strategy for the depletion of DIPs presented here can help to make cell culture-based vaccine production more reliable and robust. 相似文献