全文获取类型
收费全文 | 667篇 |
免费 | 50篇 |
国内免费 | 1篇 |
出版年
2022年 | 2篇 |
2021年 | 9篇 |
2020年 | 8篇 |
2019年 | 4篇 |
2018年 | 14篇 |
2017年 | 5篇 |
2016年 | 13篇 |
2015年 | 22篇 |
2014年 | 35篇 |
2013年 | 49篇 |
2012年 | 52篇 |
2011年 | 36篇 |
2010年 | 37篇 |
2009年 | 32篇 |
2008年 | 35篇 |
2007年 | 37篇 |
2006年 | 35篇 |
2005年 | 25篇 |
2004年 | 20篇 |
2003年 | 9篇 |
2002年 | 21篇 |
2001年 | 15篇 |
2000年 | 17篇 |
1999年 | 13篇 |
1998年 | 10篇 |
1997年 | 11篇 |
1996年 | 11篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 8篇 |
1992年 | 22篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 14篇 |
1988年 | 12篇 |
1987年 | 10篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有718条查询结果,搜索用时 15 毫秒
31.
Hui-Wen Chiu Ya-Ling Yeh Yi-Ching Wang Wei-Jan Huang Yi-An Chen Yi-Shiou Chiou Sheng-Yow Ho Pinpin Lin Ying-Jan Wang 《PloS one》2013,8(10)
Triple-negative breast cancer (TNBC), defined by the absence of an estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 expression, is associated with an early recurrence of disease and poor outcome. Furthermore, the majority of deaths in breast cancer patients are from metastases instead of from primary tumors. In this study, MCF-7 (an estrogen receptor-positive human breast cancer cell line), MDA-MB-231 (a human TNBC cell line) and 4T1 (a mouse TNBC cell line) were used to investigate the anti-cancer effects of ionizing radiation (IR) combined with suberoylanilide hydroxamic acid (SAHA, an inhibitor of histone deacetylase (HDAC)) and to determine the underlying mechanisms of these effects in vitro and in vivo. We also evaluated the ability of SAHA to inhibit the metastasis of 4T1 cells. We found that IR combined with SAHA showed increased therapeutic efficacy when compared with either treatment alone in MCF-7, MDA-MB-231 and 4T1 cells. Moreover, the combined treatment enhanced DNA damage through the inhibition of DNA repair proteins. The combined treatment was induced primarily through autophagy and ER stress. In an orthotopic breast cancer mouse model, the combination treatment showed a greater inhibition of tumor growth. In addition, SAHA inhibited the migration and invasion abilities of 4T1 cells and inhibited breast cancer cell migration by inhibiting the activity of MMP-9. In an in vivo experimental metastasis mouse model, SAHA significantly inhibited lung metastasis. SAHA not only enhances radiosensitivity but also suppresses lung metastasis in breast cancer. These novel findings suggest that SAHA alone or combined with IR could serve as a potential therapeutic strategy for breast cancer. 相似文献
32.
Atomic force microscopy provides a novel technique for differentiating the mechanical properties of various cell types. Cell elasticity is abundantly used to represent the structural strength of cells in different conditions. In this study, we are interested in whether physical or physiological cues affect cell elasticity in Atomic force microscopy (AFM)-based assessments. The physical cues include the geometry of the AFM tips, the indenting force and the operating temperature of the AFM. All of these cues show a significant influence on the cell elasticity assessment. Sharp AFM tips create a two-fold increase in the value of the effective Young’s modulus (Eeff) relative to that of the blunt tips. Higher indenting force at the same loading rate generates higher estimated cell elasticity. Increasing the operation temperature of the AFM leads to decreases in the cell stiffness because the structure of actin filaments becomes disorganized. The physiological cues include the presence of fetal bovine serum or extracellular matrix-coated surfaces, the culture passage number, and the culture density. Both fetal bovine serum and the extracellular matrix are critical for cells to maintain the integrity of actin filaments and consequently exhibit higher elasticity. Unlike primary cells, mouse kidney progenitor cells can be passaged and maintain their morphology and elasticity for a very long period without a senescence phenotype. Finally, cell elasticity increases with increasing culture density only in MDCK epithelial cells. In summary, for researchers who use AFM to assess cell elasticity, our results provide basic and significant information about the suitable selection of physical and physiological cues. 相似文献
33.
The Mediterranean fruit fly (medfly), Ceratitis capitata is among the most economically important pests worldwide. Understanding nutritional requirement helps rearing healthy medfly for biocontrol of its population in fields. Flight ability is a high priority criterion. Two groups of medfly larvae were reared with two identical component diets except one with fatty acids (diet A) and another without it (diet B). Adults from larvae reared on diet B demonstrated 20±8% of normal flight ability, whereas those from larvae reared on diet A displayed full flight ability of 97±1%. Proteomes were profiled to compare two groups of medfly pupae using shotgun proteomics to study dietary effects on flight ability. When proteins detected in pupae A were compared with those in pupae B, 233 and 239 proteins were, respectively, under- and over-expressed in pupae B, while 167 proteins were overlapped in both pupae A and B. Differential protein profiles indicate that nutritional deficiency induced over-expression of flightless-I protein (fli-I) in medfly. All proteins were subjected to Ingenuity Pathway Analysis (IPA) to create 13 biological networks and 17 pathways of interacting protein clusters in human ortholog. Fli-I, leucine-rich repeat (LRR)-containing G protein-coupled receptor 2, LRR protein soc-2 and protein wings apart-like were over-expressed in pupae B. Inositol-1,4,5-trisphosphate receptor, protocadherin-like wing polarity protein stan and several Wnt pathway proteins were under-expressed in pupae B. These results suggest down-regulation of the Wnt/wingless signaling pathway, which consequently may result in flightlessness in pupae B. The fli-I gene is known to be located within the Smith-Magenis syndrome (SMS) region on chromosome 17, and thus, we speculate that nutritional deficiency might induce over-expression of fli-I (or fli-I gene) and be associated with human SMS. However, more evidence would be needed to confirm our speculation. 相似文献
34.
Tree-based methods are popular nonparametric tools in studying time-to-event outcomes. In this article, we introduce a novel framework for survival trees and ensembles, where the trees partition the dynamic survivor population and can handle time-dependent covariates. Using the idea of randomized tests, we develop generalized time-dependent receiver operating characteristic (ROC) curves for evaluating the performance of survival trees. The tree-building algorithm is guided by decision-theoretic criteria based on ROC, targeting specifically for prediction accuracy. To address the instability issue of a single tree, we propose a novel ensemble procedure based on averaging martingale estimating equations, which is different from existing methods that average the predicted survival or cumulative hazard functions from individual trees. Extensive simulation studies are conducted to examine the performance of the proposed methods. We apply the methods to a study on AIDS for illustration. 相似文献
35.
Jiahn-Haur Liao Yu-Huan Sun Chun-Hua Hsu Yu-Ching Lin Shih-Hsiung Wu Chao-Jen Kuo Chun-Hao Huang Shyh-Horng Chiou 《Biochimie》2013
It is generally accepted that most gastrointestinal diseases are probably caused by the bacterial pathogen Helicobacter pylori (H. pylori). In this study we have focused on the comparison of protein expression profiles of H. pylori grown under normal and high-salt conditions by a proteomics approach. We have identified about 190 proteins whose expression levels changed after growth at high salt concentration. Among these proteins, neutrophil-activating protein (NapA) was found to be consistently up-regulated under osmotic stress brought by high salts. We have investigated the effect of high salt on secondary and tertiary structures of NapA by circular dichroism spectroscopy followed by analytical ultracentrifugation to monitor the change of quaternary structure of recombinant NapA with increasing salt concentration. The loss of iron-binding activity of NapA coupled with noticeable energetic variation in protein association of NapA as revealed by isothermal titration calorimetry was found under high salt condition. The phylogenetic tree analysis based on sequence comparison of 16 protein sequences encompassing NapA proteins and ferritin of H. pylori and other prokaryotic organisms pointed to the fact that all H. pylori NapA proteins of human origin are more homologous to NapA of Helicobacter genus than to other bacterial NapA. Based on computer modeling, NapA proteins from H. pylori of human isolates are found more similar to ferritin from H. pylori than to NapA from other species of bacteria. Taken together, these results suggested that divergent evolution of NapA and ferritin possessing dissimilar and diverse sequences follows a path distinct from that of convergent evolution of NapA and ferritin with similar dual functionality of iron-binding and ferroxidase activities. 相似文献
36.
Ya-Lan Chang Chin-Lin Hsieh Yao-Moan Huang Wen-Liang Chiou Yueh-Hsiung Kuo Mei-Hwei Tseng 《Analytical biochemistry》2013
A wide variety of sulfur metabolites play important roles in plant functions. We have developed a precise and sensitive method for the simultaneous measurement of several sulfur metabolites based on liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) and 34S metabolic labeling of sulfur-containing metabolites in Arabidopsis thaliana seedlings. However, some sulfur metabolites were unstable during the extraction procedure. Our proposed method does not allow for the detection of the important sulfur metabolite homocysteine because of its instability during sample extraction. Stable isotope-labeled sulfur metabolites of A. thaliana shoot were extracted and utilized as internal standards for quantification of sulfur metabolites with LC–MS/MS using S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), methionine (Met), glutathione (GSH), and glutathione disulfide (GSSG) as example metabolites. These metabolites were detected using electrospray ionization in positive mode. Standard curves were linear (r2 > 0.99) over a range of concentrations (SAM 0.01–2.0 μM, SAH 0.002–0.10 μM, Met 0.05–4.0 μM, GSH 0.17–20.0 μM, GSSG 0.07–20.0 μM), with limits of detection for SAM, SAH, Met, GSH, and GSSG of 0.83, 0.67, 10, 0.56, and 1.1 nM, respectively; and the within-run and between-run coefficients of variation based on quality control samples were less than 8%. 相似文献
37.
Chiou‐Chu Su Chung Jan Chang Che‐Ming Chang Hsien‐Tzung Shih Kuo‐Ching Tzeng Fuh‐Jyh Jan Chin‐Wen Kao Wen‐Ling Deng 《Journal of Phytopathology》2013,161(6):389-396
Characteristic symptoms of Pierce's disease (PD) in grapevines (Vitis vinifera L.) were observed in 2002 in the major grape production fields of central Taiwan. Disease severity in vineyards varied, and all investigated grape cultivars were affected. Diseased tissues were collected from fields for subsequent isolation and characterization of the causal agent of the disease (Xylella fastidiosa). Koch's postulates were fulfilled by artificially inoculating two purified PD bacteria to grape cultivars Kyoho, Honey Red and Golden Muscat. The inoculated plants developed typical leaf‐scorching symptoms, and similar disease severity developed in the three cultivars from which the bacterium was readily re‐isolated, proving that the leaf scorch of grapevines in Taiwan is caused by the fastidious X. fastidiosa. This confirmed PD of grapevines is also the first report from the Asian Continent. Phylogenetic analyses were performed by comparing the 16S rRNA gene and 16S‐23S rRNA internal transcribed spacer region (16S‐23S ITS) of 12 PD strains from Taiwan with the sequences of 13 X. fastidiosa strains from different hosts and different geographical areas. Results showed that the PD strains of Taiwan were closely related to the American X. fastidiosa grape strains but not to the pear strains of Taiwan, suggesting that the X. fastidiosa grape and pear strains of Taiwan may have evolved independently from each other. 相似文献
38.
Background and Purpose
The aim was to identify the risk factors for renal scarring and deteriorating renal function in children with primary vesico-ureteral reflux (VUR).Materials and Methods
Patients with primary VUR admitted to the National Cheng Kung University Hospital were retrospectively analyzed. The outcomes were renal scarring, assessed by technetium-99 m dimercaptosuccinic acid scanning, and renal function, assessed by estimated glomerular filtration rate. Univariate and multivariate models were applied to identify the corresponding independent predictors.Results
A total of 173 patients with primary VUR were recruited. The median age of VUR diagnosis was 10.0 months (IQR: 4.0–43.0 months). After adjusting for confounding factors, it was found that older age of VUR diagnosis (≥5 years vs. <1 year, adjusted OR = 2.78, 95% CI = 1.00–7.70, p = 0.049), higher grade of VUR (high grade [IV–V] vs. none, adjusted OR = 15.17, 95% CI = 5.33–43.19, p<0.0001; low grade [I–III] vs. none, adjusted OR = 5.72, 95% CI = 2.43–13.45, p<0.0001), and higher number of UTI (≥2 vs. 0, adjusted OR = 3.21, 95% CI = 1.06–9.76, p = 0.039) were risk factors for renal scarring, whereas a younger age of VUR diagnosis (≥5 years vs. <1 year, adjusted HR = 0.16, 95% CI: 0.05–0.51, p = 0.002), renal scarring (yes vs. no, adjusted HR = 3.66, 95% CI: 1.32–10.16, p = 0.013), and APN (yes vs. no, adjusted HR = 3.10, 95% CI: 1.05–9.14, p = 0.041) were risk factors for developing chronic kidney disease stage 2 or higher.Conclusions
Our findings expand on the current knowledge of risk factors for renal scarring and deteriorating renal function, and this information can be used to modify the management and treatment of VUR. 相似文献39.
Chien-Wei Su Yu-Wei Chiou Yi-Hsuan Tsai Ruei-Dun Teng Gar-Yang Chau Hao-Jan Lei Hung-Hsu Hung Teh-Ia Huo Jaw-Ching Wu 《PloS one》2013,8(6)
Background
Whether or not hepatitis B virus (HBV) genotypes, mutations, and viral loads determine outcomes for patients with HBV-induced hepatocellular carcinoma (HCC) remains controversial.Aims
To study the influence of HBV viral factors on prognoses for patients with HBV-induced HCC after resection surgery and investigate if antiviral therapy could counteract the adverse effects of viral factors.Methods
A total of 333 HBV-related HCC patients who underwent tumor resection were enrolled retrospectively. Serum HBV DNA levels, mutations, anti-viral therapy, and other clinical variables were analyzed for their association with post-operative recurrence.Results
After a median follow-up of 45.9 months, 208 patients had HCC recurrence after resection. The 5-year overall survival and recurrence-free survival rates were 55.4% and 35.3%, respectively. Multivariate analysis showed indocyanine green retention rate at 15 minutes >10%, gamma-glutamyltransferase (GGT) level >60 U/L, macroscopic and microscopic venous invasion, and the absence of anti-viral therapy were significant risk factors for recurrence. Anti-viral therapy could decrease recurrence in patients with early stage HCC, but the effect was less apparent in those with the Barcelona-Clinic Liver Cancer stage C HCC. For patients without antiviral therapy after resection, serum HBV DNA levels >106 copies/mL, GGT >60 U/L, and macroscopic and microscopic venous invasion were significant risk factors predicting recurrence. Among the 216 patients without anti-viral therapy but with complete HBV surface gene mapping data, 73 were with pre-S deletion mutants. Among patients with higher serum HBV DNA levels, those with pre-S deletion had significantly higher rates of recurrence. Moreover, multivariate analysis showed multi-nodularity, macroscopic venous invasion, cirrhosis, advanced tumor cell differentiation, and pre-S deletion were significant risk factors predictive of recurrence.Conclusions
Ongoing HBV viral replication and pre-S deletion are crucial for determining post-operative tumor recurrence. Anti-viral therapy can help reduce recurrence and improve prognosis, especially for those with early stage HCC. 相似文献40.
KB Cullberg T Christiansen SK Paulsen JM Bruun SB Pedersen B Richelsen 《Obesity (Silver Spring, Md.)》2013,21(3):454-460