全文获取类型
收费全文 | 2081篇 |
免费 | 164篇 |
专业分类
2245篇 |
出版年
2023年 | 13篇 |
2022年 | 33篇 |
2021年 | 63篇 |
2020年 | 27篇 |
2019年 | 40篇 |
2018年 | 53篇 |
2017年 | 38篇 |
2016年 | 63篇 |
2015年 | 109篇 |
2014年 | 111篇 |
2013年 | 136篇 |
2012年 | 197篇 |
2011年 | 175篇 |
2010年 | 99篇 |
2009年 | 77篇 |
2008年 | 124篇 |
2007年 | 116篇 |
2006年 | 111篇 |
2005年 | 105篇 |
2004年 | 86篇 |
2003年 | 83篇 |
2002年 | 64篇 |
2001年 | 25篇 |
2000年 | 17篇 |
1999年 | 20篇 |
1998年 | 13篇 |
1997年 | 8篇 |
1996年 | 11篇 |
1995年 | 9篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 14篇 |
1991年 | 15篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 10篇 |
1987年 | 13篇 |
1986年 | 9篇 |
1985年 | 11篇 |
1984年 | 12篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1974年 | 10篇 |
1973年 | 10篇 |
1970年 | 5篇 |
1967年 | 5篇 |
排序方式: 共有2245条查询结果,搜索用时 13 毫秒
51.
Heather A Huet Joseph D Growney Jennifer A Johnson Jing Li Sanela Bilic Lance Ostrom Mohammad Zafari Colleen Kowal Guizhi Yang Axelle Royo Michael Jensen Bruno Dombrecht Kris RA Meerschaert Joost A Kolkman Karen D Cromie Rebecca Mosher Hui Gao Alwin Schuller Randi Isaacs William R Sellers Seth A Ettenberg 《MABS-AUSTIN》2014,6(6):1560-1570
Multiple therapeutic agonists of death receptor 5 (DR5) have been developed and are under clinical evaluation. Although these agonists demonstrate significant anti-tumor activity in preclinical models, the clinical efficacy in human cancer patients has been notably disappointing. One possible explanation might be that the current classes of therapeutic molecules are not sufficiently potent to elicit significant response in patients, particularly for dimeric antibody agonists that require secondary cross-linking via Fcγ receptors expressed on immune cells to achieve optimal clustering of DR5. To overcome this limitation, a novel multivalent Nanobody approach was taken with the goal of generating a significantly more potent DR5 agonist. In the present study, we show that trivalent DR5 targeting Nanobodies mimic the activity of natural ligand, and furthermore, increasing the valency of domains to tetramer and pentamer markedly increased potency of cell killing on tumor cells, with pentamers being more potent than tetramers in vitro. Increased potency was attributed to faster kinetics of death-inducing signaling complex assembly and caspase-8 and caspase-3 activation. In vivo, multivalent Nanobody molecules elicited superior anti-tumor activity compared to a conventional DR5 agonist antibody, including the ability to induce tumor regression in an insensitive patient-derived primary pancreatic tumor model. Furthermore, complete responses to Nanobody treatment were obtained in up to 50% of patient-derived primary pancreatic and colon tumor models, suggesting that multivalent DR5 Nanobodies may represent a significant new therapeutic modality for targeting death receptor signaling. 相似文献
52.
Hui Yang Seth M. Munson Chris Huntingford Nuno Carvalhais Alan K. Knapp Xiangyi Li Josep Peñuelas Jakob Zscheischler Anping Chen 《Global Change Biology》2023,29(8):2351-2362
Negative extreme anomalies in vegetation growth (NEGs) usually indicate severely impaired ecosystem services. These NEGs can result from diverse natural and anthropogenic causes, especially climate extremes (CEs). However, the relationship between NEGs and many types of CEs remains largely unknown at regional and global scales. Here, with satellite-derived vegetation index data and supporting tree-ring chronologies, we identify periods of NEGs from 1981 to 2015 across the global land surface. We find 70% of these NEGs are attributable to five types of CEs and their combinations, with compound CEs generally more detrimental than individual ones. More importantly, we find that dominant CEs for NEGs vary by biome and region. Specifically, cold and/or wet extremes dominate NEGs in temperate mountains and high latitudes, whereas soil drought and related compound extremes are primarily responsible for NEGs in wet tropical, arid and semi-arid regions. Key characteristics (e.g., the frequency, intensity and duration of CEs, and the vulnerability of vegetation) that determine the dominance of CEs are also region- and biome-dependent. For example, in the wet tropics, dominant individual CEs have both higher intensity and longer duration than non-dominant ones. However, in the dry tropics and some temperate regions, a longer CE duration is more important than higher intensity. Our work provides the first global accounting of the attribution of NEGs to diverse climatic extremes. Our analysis has important implications for developing climate-specific disaster prevention and mitigation plans among different regions of the globe in a changing climate. 相似文献
53.
Hu CJ Song G Huang W Liu GZ Deng CW Zeng HP Wang L Zhang FC Zhang X Jeong JS Blackshaw S Jiang LZ Zhu H Wu L Li YZ 《Molecular & cellular proteomics : MCP》2012,11(9):669-680
Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease of unknown etiology and is considered to be an autoimmune disease. Autoantibodies are important tools for accurate diagnosis of PBC. Here, we employed serum profiling analysis using a human proteome microarray composed of about 17,000 full-length unique proteins and identified 23 proteins that correlated with PBC. To validate these results, we fabricated a PBC-focused microarray with 21 of these newly identified candidates and nine additional known PBC antigens. By screening the PBC microarrays with additional cohorts of 191 PBC patients and 321 controls (43 autoimmune hepatitis, 55 hepatitis B virus, 31 hepatitis C virus, 48 rheumatoid arthritis, 45 systematic lupus erythematosus, 49 systemic sclerosis, and 50 healthy), six proteins were confirmed as novel PBC autoantigens with high sensitivities and specificities, including hexokinase-1 (isoforms I and II), Kelch-like protein 7, Kelch-like protein 12, zinc finger and BTB domain-containing protein 2, and eukaryotic translation initiation factor 2C, subunit 1. To facilitate clinical diagnosis, we developed ELISA for Kelch-like protein 12 and zinc finger and BTB domain-containing protein 2 and tested large cohorts (297 PBC and 637 control sera) to confirm the sensitivities and specificities observed in the microarray-based assays. In conclusion, our research showed that a strategy using high content protein microarray combined with a smaller but more focused protein microarray can effectively identify and validate novel PBC-specific autoantigens and has the capacity to be translated to clinical diagnosis by means of an ELISA-based method. 相似文献
54.
Cohen SD Armenakas NA Light DM Fracchia JA Glasberg SB 《Plastic and reconstructive surgery》2012,130(1):101-104
Although buccal mucosa has been the preferred graft material for use in the reconstruction of anterior urethral strictures for approximately 20 years, the plastic surgery literature is lacking in studies describing and evaluating this technique. The authors sought to report their experience with the technique of buccal mucosa graft harvest for use in urethral reconstruction. The authors identified 87 consecutive patients who underwent buccal mucosal graft harvesting during a 15-year period from 1995 to 2010. All donor sites were closed primarily. Preoperatively, a specialty-specific evaluation was performed by plastic surgeons and urologists. Postoperative donor-site morbidity was followed clinically. Eighty-seven patients underwent buccal harvesting. A single buccal graft was harvested in 75 patients (86.2 percent) and bilateral grafts were harvested in 12 patients (13.8 percent). The median patient age of the patients was 42 years (range, 16 to 78 years). There were no major intraoperative or postoperative complications. Minor complications included mild discomfort, numbness, cheek swelling, and restriction of oral movement, all of which resolved by the 3-month postoperative visit. The ability to eat and drink postoperatively was diminished during only the first 24 to 48 hours in all patients. Our series provides a 1-year follow-up in a substantial cohort looking at clinical outcomes after buccal harvesting. These results confirm the safety and efficacy of buccal mucosal harvesting to provide an effective and cosmetically superior option for urethral reconstruction. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV. 相似文献
55.
Seth M. Kelly Sara W. Leung ChangHui Pak Ayan Banerjee Kenneth H. Moberg Anita H. Corbett 《RNA (New York, N.Y.)》2014,20(5):681-688
The ZC3H14 gene, which encodes a ubiquitously expressed, evolutionarily conserved, nuclear, zinc finger polyadenosine RNA-binding protein, was recently linked to autosomal recessive, nonsyndromic intellectual disability. Although studies have been carried out to examine the function of putative orthologs of ZC3H14 in Saccharomyces cerevisiae, where the protein is termed Nab2, and Drosophila, where the protein has been designated dNab2, little is known about the function of mammalian ZC3H14. Work from both budding yeast and flies implicates Nab2/dNab2 in poly(A) tail length control, while a role in poly(A) RNA export from the nucleus has been reported only for budding yeast. Here we provide the first functional characterization of ZC3H14. Analysis of ZC3H14 function in a neuronal cell line as well as in vivo complementation studies in a Drosophila model identify a role for ZC3H14 in proper control of poly(A) tail length in neuronal cells. Furthermore, we show here that human ZC3H14 can functionally substitute for dNab2 in fly neurons and can rescue defects in development and locomotion that are present in dNab2 null flies. These rescue experiments provide evidence that this zinc finger-containing class of nuclear polyadenosine RNA-binding proteins plays an evolutionarily conserved role in controlling the length of the poly(A) tail in neurons. 相似文献
56.
Ansong D Asante KP Vekemans J Owusu SK Owusu R Brobby NA Dosoo D Osei-Akoto A Osei-Kwakye K Asafo-Adjei E Boahen KO Sylverken J Adjei G Sambian D Apanga S Kayan K Janssens MH Lievens MJ Olivier AC Jongert E Dubois P Savarese BM Cohen J Antwi S Greenwood BM Evans JA Agbenyega T Moris PJ Owusu-Agyei S 《PloS one》2011,6(4):e18891
Background
The Plasmodium falciparum pre-erythrocytic stage candidate vaccine RTS,S is being developed for protection of young children against malaria in sub-Saharan Africa. RTS,S formulated with the liposome based adjuvant AS01E or the oil-in-water based adjuvant AS02D induces P. falciparum circumsporozoite (CSP) antigen-specific antibody and T cell responses which have been associated with protection in the experimental malaria challenge model in adults.Methods
This study was designed to evaluate the safety and immunogenicity induced over a 19 month period by three vaccination schedules (0,1-, 0,1,2- and 0,1,7-month) of RTS,S/AS01E and RTS,S/AS02D in children aged 5–17 months in two research centers in Ghana. Control Rabies vaccine using the 0,1,2-month schedule was used in one of two study sites.Results
Whole blood antigen stimulation followed by intra-cellular cytokine staining showed RTS,S/AS01E induced CSP specific CD4 T cells producing IL-2, TNF-α, and IFN-γ. Higher T cell responses were induced by a 0,1,7-month immunization schedule as compared with a 0,1- or 0,1,2-month schedule. RTS,S/AS01E induced higher CD4 T cell responses as compared to RTS,S/AS02D when given on a 0,1,7-month schedule.Conclusions
These findings support further Phase III evaluation of RTS,S/AS01E. The role of immune effectors and immunization schedules on vaccine protection are currently under evaluation.Trial Registration
ClinicalTrials.gov NCT00360230相似文献57.
58.
Timothy A. McCaffrey Domenick J. Falcone Diane Vicente Baoheng Du Seth Consigli Wolfgang Borth 《Journal of cellular physiology》1994,159(1):51-59
The transforming growth factor-β (TGF-β) family of proteins exert diverse and potent effects on proliferation, differentiation, and extracellular matrix synthesis. However, relatively little is known about the stability or processing of endogenous TGF-β activity in vitro or in vivo. Our previous work indicated that (1) TGF-β1 has strong heparin-binding properties that were not previously recognized because of neutralization by iodination, and (2) heparin, and certain other polyanions, could block the binding of TGF-β1 to α2-macroglobulin (α2-M). The present studies investigated the influence of heparin-like molecules on the stability of the TGF-β1 signal in the pericellular environment. The results indicate that heparin and fucoidan, a naturally occurring sulfated L-fucose polymer, suppress the formation of an initial non-covalent interaction between 125I-TGF-β1 and activated α2-M. Electrophoresis of 125I-TGF-β1 showed that fucoidan protects TGF-β1 from proteolytic degradation by plasmin and trypsin. While plasmin caused little, if any, activation of latent TGF-β derived from vascular smooth muscle cells (SMC), plasmin degraded acid-activated TGF-β, and purified TGF-β1, and this degradation was inhibited by fucoidan. In vitro, heparin and fucoidan tripled the half-life of 125I-TGF-β1 and doubled the amount of cell-associated 125I-TGF-β1. Consistent with this protective effect, heparin- and fucoidan-treated SMC demonstrated elevated levels of active, but not latent, TGF-β activity. © 1994 wiley-Liss, Inc. 相似文献
59.
Ejaculates from 3 young boars were collected on 4 occasions as a series of separate 15-ml fractions. The contribution of different fractions of these ejaculates to observed variability in the quality of the semen when used for IVF was then determined. On the basis of sperm concentration, 3 fractions representing the first peak concentration (Fraction 1), the lowest sperm concentration after Fraction 1 (Fraction 2), and the second peak concentration (Fraction 3) were selected for analysis in vitro. Oocyte-cumulus-granulosa cell complexes were obtained by dissection from slaughterhouse ovaries. In vitro matured oocytes were randomly assigned for fertilization by the 3 semen samples from each boar. Sperm concentration was the same in all the samples during prefertilization incubation, while the final concentration for fertilization was 5 x 10(5) sperm/ml. Data were analysed using ANOVA for a split-plot design. In the presence of fraction effects, Student-Newman-Keuls (SNK) test was used for multiple comparison of treatment means. Oocyte penetration rates differed among fractions (P = 0.001) and varied from 69 to 100% (mean 95.7%) for Fraction 1, from 0 to 100% (mean 53.3%) for Fraction 2, and from 50to 100% (mean 89.9%) for Fraction 3. There were also differences in male pronuclear formation rate (P = 0.028; mean 27.6, 9.3 and 16.4% for Fractions 1, 2 and 3, respectively); in the rate of polyspermy (P = 0.0001; mean 92.3, 31.9 and 76.3% for Fractions 1, 2 and 3, respectively); and in the number of penetrated spermatozoa per oocyte P = 0.002; mean 5.58, 1.94 and 4.07 for Fractions 1, 2, and 3, respectively). The first peak concentration of semen (Fraction 1) showed superiority in fertilizing ability and less variability in penetration rate from replicate to replicate compared with the other 2 fractions. By multiple comparison, Boar 1 showed higher rates of penetration (P < 0.05), male pronuclear formation (P < 0.05) and polyspermy (P < 0.05) than the other 2 boars. There was no fraction-by-boar interaction. The IVM-IVF system adopted proved to be a promising method for boar semen evaluation. 相似文献
60.
Madhuram Khandelwal Vivek Anand Sandeep Appunni Amlesh Seth Prabhjot Singh Sandeep Mathur Alpana Sharma 《Molecular and cellular biochemistry》2018,439(1-2):105-115
During the past decade, microRNAs have continuously been suggested as a promising therapeutic tool due to their beneficial effects, such as their multi-targets and multi-functions in pathologic conditions. As a pathologic phenotype is generally regulated by multiple signaling pathways, in this study we identified a microRNA regulating multiple target genes within cardiac hypertrophic signaling pathways. microRNA-133a is known to play a crucial role in cardiac hypertrophy. However, the role of microRNA-133a, which may regulate several signaling pathways in norepinephrine-induced cardiac hypertrophy via multi-targeting, has not been investigated. In the current study, we showed that microRNA-133a can protect cardiomyocyte hypertrophy against norepinephrine stimulation in neonatal rat ventricular cardiomyocytes via new targets, PKCδ and Gq, all of which are related to downstream signaling pathways of the α1-adrenergic receptor. Taken together, these results suggest the advantages of the therapeutic use of microRNAs as an effective potential drug regulating multiple signaling pathways under pathologic conditions. 相似文献