全文获取类型
收费全文 | 25847篇 |
免费 | 1620篇 |
国内免费 | 81篇 |
专业分类
耳鼻咽喉 | 179篇 |
儿科学 | 809篇 |
妇产科学 | 618篇 |
基础医学 | 3890篇 |
口腔科学 | 450篇 |
临床医学 | 3716篇 |
内科学 | 4689篇 |
皮肤病学 | 438篇 |
神经病学 | 2702篇 |
特种医学 | 600篇 |
外科学 | 2096篇 |
综合类 | 173篇 |
一般理论 | 26篇 |
预防医学 | 2995篇 |
眼科学 | 445篇 |
药学 | 1869篇 |
1篇 | |
中国医学 | 56篇 |
肿瘤学 | 1796篇 |
出版年
2024年 | 23篇 |
2023年 | 211篇 |
2022年 | 386篇 |
2021年 | 712篇 |
2020年 | 467篇 |
2019年 | 635篇 |
2018年 | 772篇 |
2017年 | 549篇 |
2016年 | 608篇 |
2015年 | 789篇 |
2014年 | 907篇 |
2013年 | 1452篇 |
2012年 | 2019篇 |
2011年 | 2168篇 |
2010年 | 1128篇 |
2009年 | 1057篇 |
2008年 | 1759篇 |
2007年 | 1826篇 |
2006年 | 1776篇 |
2005年 | 1661篇 |
2004年 | 1571篇 |
2003年 | 1442篇 |
2002年 | 1266篇 |
2001年 | 165篇 |
2000年 | 126篇 |
1999年 | 170篇 |
1998年 | 220篇 |
1997年 | 168篇 |
1996年 | 161篇 |
1995年 | 116篇 |
1994年 | 125篇 |
1993年 | 106篇 |
1992年 | 72篇 |
1991年 | 86篇 |
1990年 | 71篇 |
1989年 | 78篇 |
1988年 | 47篇 |
1987年 | 47篇 |
1986年 | 47篇 |
1985年 | 49篇 |
1984年 | 67篇 |
1983年 | 72篇 |
1982年 | 70篇 |
1981年 | 48篇 |
1980年 | 50篇 |
1979年 | 34篇 |
1978年 | 22篇 |
1977年 | 25篇 |
1976年 | 24篇 |
1974年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
YKL-40 expression is associated with poorer response to radiation and shorter overall survival in glioblastoma. 总被引:7,自引:0,他引:7
Christopher E Pelloski Anita Mahajan Moshe Maor Eric L Chang Shiao Woo Mark Gilbert Howard Colman Helen Yang Alicia Ledoux Hilary Blair Sandra Passe Robert B Jenkins Kenneth D Aldape 《Clinical cancer research》2005,11(9):3326-3334
PURPOSE: YKL-40 is a secreted protein that has been reported to be overexpressed in epithelial cancers and gliomas, although its function is unknown. Previous data in a smaller sample set suggested that YKL-40 was a marker associated with a poorer clinical outcome and a genetically defined subgroup of glioblastoma. Here we test these findings in a larger series of patients with glioblastoma, and in particular, determine if tumor YKL-40 expression is associated with radiation response. EXPERIMENTAL DESIGN: Patients (n=147) with subtotal resections were studied for imaging-assessed changes in tumor size in serial studies following radiation therapy. An additional set (n=140) of glioblastoma patients who underwent a gross-total resection was tested to validate the survival association and extend them to patients with minimal residual disease. RESULTS: In the subtotal resection group, higher YKL-40 expression was significantly associated with poorer radiation response, shorter time to progression and shorter overall survival. The association of higher YKL-40 expression with poorer survival was validated in the gross-total resection group. In multivariate analysis with both groups combined (n = 287), YKL-40 was an independent predictor of survival after adjusting for patient age, performance status, and extent of resection. YKL-40 expression was also compared with genetically defined subsets of glioblastoma by assessing epidermal growth factor receptor amplification and loss at chromosome 10q, two of the common recurring aberrations in these tumors, using fluorescent in situ hybridization. YKL-40 was significantly associated with 10q loss. CONCLUSIONS: The findings implicate YKL-40 as an important marker of therapeutic response and genetic subtype in glioblastomas and suggest that it may play an oncogenic role in these tumors. 相似文献
112.
113.
Lina Widerspick Cecilia Alejandra Vzquez Linda Niemetz Michelle Heung Catherine Olal Andrs Bencsik Christoph Henkel Anneke Pfister Jesús Emanuel Brunetti Indre Kucinskaite-Kodze Philip Lawrence Csar Muoz Fontela Sandra Diederich Beatriz Escudero-Prez 《Viruses》2022,14(5)
Nipah virus (NiV) is an emerging zoonotic paramyxovirus that causes severe disease in humans and livestock. Due to its high pathogenicity in humans and the lack of available vaccines and therapeutics, NiV needs to be handled in biosafety level 4 (BSL-4) laboratories. Safe inactivation of samples containing NiV is thus necessary to allow further processing in lower containment areas. To date, there is only limited information available on NiV inactivation methods validated by BSL-4 facilities that can be used as a reference. Here, we compare some of the most common inactivation methods in order to evaluate their efficacy at inactivating NiV in infected cells, supernatants and organs. Thus, several physical and chemical inactivation methods, and combinations thereof, were assessed. Viral replication was monitored for 3 weeks and NiV presence was assessed by RT-qPCR, plaque assay and indirect immunofluorescence. A total of nineteen methods were shown to reduce NiV infectious particles in cells, supernatants and organs to undetectable levels. Therefore, we provide a list of methods for the safe and efficient inactivation of NiV. 相似文献
114.
Jae-Yung Kwon Lara Russell Theresa Coles Robert J. Klaassen Kara Schick-Makaroff Kathryn M. Sibley Sandra A. Mitchell Richard Sawatzky 《Current oncology (Toronto, Ont.)》2022,29(5):3093
Tools for measuring patients’ perceived health and quality of life, such as patient-reported outcome measures (PROMs), inform clinical decisions for patients requiring radiation therapy. However, there may be inconsistencies in how patients interpret and respond to PROMs due to cultural, environmental, personal, or experiential factors. Differential item functioning (DIF) and response shift (RS) refer to differences in the meaning of PROMs between patients or over time (respectively). DIF and RS can threaten the accurate interpretation and use of PROMs, potentially resulting in erroneous conclusions about effectiveness, and flawed individual-level clinical decision-making. Given the empirical evidence of DIF and RS, we aim to review clinical implications and solutions for addressing DIF and RS by providing vignettes from collaborative examinations with workshop participants, as well as the literature. By making these methodological concepts accessible and relevant, for practice, clinicians may feel more confident to ask clarifying questions of patients when PROM scores and the contextual patient information do not align. PROM scores need to be interpreted via dialogue with the patient to avoid misinterpretation due to DIF and RS, which could diminish patient–clinician communication and impede shared decision-making. This work is part of an interdisciplinary knowledge translation initiative focused on the interpretation of PROM scores by clinically-oriented audiences. 相似文献
115.
Sandra Lepak-Kuc Katarzyna Wasilewska Daniel Janczak Tatiana Nowicka Magorzata Jakubowska 《Materials》2022,15(10)
In this study, the extremely important and difficult topic of flexographic printing on a heat-shrinkable substrate was taken up. Six commercially available, electrically conductive inks based on silver, copper and graphite nanoparticles were selected and tested upon their applicability for printing on the temperature-sensitive PET material. As a printing substrate, the one-direction heat-shrinkable PET film, with a maximum shrinkage of 78%, was selected. All of the examined inks were subjected to the printing process throughout three different anilox line screens. The tested inks, along with the electric paths printed with them, were subjected to various tests. The main parameters were evaluated, such as printability combined with the rheology tests and ink adhesion to the examined PET substrate together with the electrical conductivity before and after the shrinkage. 相似文献
116.
Natalia Carrillo-Lpez Sara Panizo Maria Vittoria Arcidiacono Sandra de la Fuente Laura Martínez-Arias Emerenziana Ottaviano Catalina Ulloa María Piedad Ruiz-Torres Isabel Rodríguez Jorge B. Cannata-Andía Manuel Naves-Díaz Adriana S. Dusso 《Nutrients》2022,14(13)
In chronic kidney disease, systemic inflammation and high serum phosphate (P) promote the de-differentiation of vascular smooth muscle cells (VSMC) to osteoblast-like cells, increasing the propensity for medial calcification and cardiovascular mortality. Vascular microRNA-145 (miR-145) content is essential to maintain VSMC contractile phenotype. Because vitamin D induces aortic miR-145, uremia and high serum P reduce it and miR-145 directly targets osteogenic osterix in osteoblasts, this study evaluated a potential causal link between vascular miR-145 reductions and osterix-driven osteogenic differentiation and its counter-regulation by vitamin D. Studies in aortic rings from normal rats and in the rat aortic VSMC line A7r5 exposed to calcifying conditions corroborated that miR-145 reductions were associated with decreases in contractile markers and increases in osteogenic differentiation and calcium (Ca) deposition. Furthermore, miR-145 silencing enhanced Ca deposition in A7r5 cells exposed to calcifying conditions, while miR-145 overexpression attenuated it, partly through increasing α-actin levels and reducing osterix-driven osteogenic differentiation. In mice, 14 weeks after the induction of renal mass reduction, both aortic miR-145 and α-actin mRNA decreased by 80% without significant elevations in osterix or Ca deposition. Vitamin D treatment from week 8 to 14 fully prevented the reductions in aortic miR-145 and attenuated by 50% the decreases in α-actin, despite uremia-induced hyperphosphatemia. In conclusion, vitamin D was able to prevent the reductions in aortic miR-145 and α-actin content induced by uremia, reducing the alterations in vascular contractility and osteogenic differentiation despite hyperphosphatemia. 相似文献
117.
The toxicology of perfluorooctanoate 总被引:10,自引:0,他引:10
Kennedy GL Butenhoff JL Olsen GW O'Connor JC Seacat AM Perkins RG Biegel LB Murphy SR Farrar DG 《Critical reviews in toxicology》2004,34(4):351-384
PFOA is a peroxisome proliferator (PPAR agonist) and exerts morphological and biochemical effects characteristic of PPAR agonists. These effects include increased beta-oxidation of fatty acids, increases in several cytochrome P-450 (CYP450)-mediated reactions, and inhibition of the secretion of very low-density lipoproteins and cholesterol from the liver. These effects on lipid metabolism and transport result in a reduction of cholesterol and triglycerides in serum and an accumulation of lipids in the liver. The triad of tumors observed (liver, Leydig cell, and pancreatic acinar-cell) is typical of many PPAR agonists and is believed to involve nongenotoxic mechanisms. The hepatocellular tumors observed in rats are likely to have been the result of the activation of the peroxisome proliferator activated receptor alpha (PPARalpha). The tumors observed in the testis (Leydig-cell) have been hypothesized to be associated with an increased level of serum estradiol in concert with testicular growth factors. The mechanism responsible for the acinar-cell tumors of the pancreas in rats remains the subject of active investigation. The mechanism resulting in the hepatocellular tumors in rats (PPARalpha activation) is not likely to be relevant to humans. Similarly, the proposed mechanism for Leydig-cell tumor formation is of questionable relevance to humans. Acinar tumors of the pancreas are rare in humans, and the relevance of the these tumors, as found in rats, to humans is uncertain. Epidemiological investigations and medical surveillance of occupationally exposed workers have not found consistent associations between PFOA exposure and adverse health effects. 相似文献
118.
Mariana Fernndez-Lizrraga Julieta García-Lpez Sandra E. Rodil Rosa María Ribas-Aparicio Phaedra Silva-Bermudez 《Materials》2022,15(15)
Biomaterials with adequate properties to direct a biological response are essential for orthopedic and dental implants. The surface properties are responsible for the biological response; thus, coatings with biologically relevant properties such as osteoinduction are exciting options to tailor the surface of different bulk materials. Metal oxide coatings such as TiO2, ZrO2, Nb2O5 and Ta2O5 have been suggested as promising for orthopedic and dental implants. However, a comparative study among them is still missing to select the most promising for bone-growth-related applications. In this work, using magnetron sputtering, TiO2, ZrO2, Ta2O5, and Nb2O5 thin films were deposited on Si (100) substrates. The coatings were characterized by Optical Profilometry, Scanning Electron Microscopy, Energy-Dispersive X-ray Spectroscopy, X-ray Photoelectron Spectroscopy, X-ray Diffraction, Water Contact Angle measurements, and Surface Free Energy calculations. The cell adhesion, viability, proliferation, and differentiation toward the osteoblastic phenotype of mesenchymal stem cells plated on the coatings were measured to define the biological response. Results confirmed that all coatings were biocompatible. However, a more significant number of cells and proliferative cells were observed on Nb2O5 and Ta2O5 compared to TiO2 and ZrO2. Nevertheless, Nb2O5 and Ta2O5 seemed to induce cell differentiation toward the osteoblastic phenotype in a longer cell culture time than TiO2 and ZrO2. 相似文献
119.
Edelstein A Yavetz H Kleiman SE Botchan A Hauser R Paz G Yogev L 《Fertility and sterility》2008,90(1):205-208
A similarity was found between the percentage of thawed, DNA-damaged spermatozoa in cancer patients and that in candidates to become sperm bank donors who had low sperm cryofreezability. Both groups were significantly different from the sperm bank donor group. It is suggested that the higher rate of DNA fragmentation in sperm from cancer patients compared with sperm bank donors is apparently a result of selecting donors by the level of sperm cryofreezability (i.e., high), rather than a direct effect of an existing malignancy. 相似文献
120.