全文获取类型
收费全文 | 7360篇 |
免费 | 591篇 |
国内免费 | 39篇 |
出版年
2024年 | 10篇 |
2023年 | 36篇 |
2022年 | 111篇 |
2021年 | 163篇 |
2020年 | 119篇 |
2019年 | 182篇 |
2018年 | 223篇 |
2017年 | 197篇 |
2016年 | 326篇 |
2015年 | 446篇 |
2014年 | 479篇 |
2013年 | 547篇 |
2012年 | 683篇 |
2011年 | 657篇 |
2010年 | 481篇 |
2009年 | 376篇 |
2008年 | 478篇 |
2007年 | 449篇 |
2006年 | 384篇 |
2005年 | 331篇 |
2004年 | 314篇 |
2003年 | 283篇 |
2002年 | 279篇 |
2001年 | 45篇 |
2000年 | 65篇 |
1999年 | 61篇 |
1998年 | 38篇 |
1997年 | 37篇 |
1996年 | 24篇 |
1995年 | 26篇 |
1994年 | 19篇 |
1993年 | 10篇 |
1992年 | 10篇 |
1991年 | 16篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1979年 | 4篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1972年 | 3篇 |
1968年 | 3篇 |
1964年 | 3篇 |
1963年 | 2篇 |
排序方式: 共有7990条查询结果,搜索用时 15 毫秒
101.
Hari Datta Bhattarai Babita Paudel Kim Il Chan Hyuncheol Oh Joung Han Yim 《Phytochemistry letters》2013,6(4):536-538
A new fused tetracyclic heterocyclic compound, (4bR,10bR)-4b-hydroxy-10b,12-dihydrodibenzo[c,h][2,6]naphthyridine-5,11(4bH,6H)-dione (1), and a known compound, butyl 2-[(benzoyloxy)methyl]benzoate, spatozoate 2, were isolated from the broth culture of Serratia sp. PAMC 25557. The structure of 1 was determined by analyzing spectroscopic data. Compound 1 did not exhibit antimicrobial activity against Escherichia coli, Staphylococcus aureus, or Candida albicans. In addition, up to 100 μg/ml compound 1 did not show any toxicity against Artemia salina larvae. However, compound 1 showed DPPH free radical scavenging activity (IC50 = 16.7 ± 0.34 μg/ml). This was the first report of spatozoate isolation from bacterial sources. 相似文献
102.
Although Aurora B is important in cleavage furrow ingression and completion during cytokinesis, the mechanism by which kinase activity is targeted to the cleavage furrow and the molecule(s) responsible for this process have remained elusive. Here, we demonstrate that an essential mitotic kinesin MKlp2 requires myosin-II for its localization to the equatorial cortex, and this event is required to recruit Aurora B to the equatorial cortex in mammalian cells. This recruitment event is also required to promote the highly focused accumulation of active RhoA at the equatorial cortex and stable ingression of the cleavage furrow in bipolar cytokinesis. Specifically, in drug-induced monopolar cytokinesis, targeting Aurora B to the cell cortex by MKlp2 is essential for cell polarization and furrow formation. Once the furrow has formed, MKlp2 further recruits Aurora B to the growing furrow. This process together with continuous Aurora B kinase activity at the growing furrow is essential for stable furrow propagation and completion. In contrast, a MKlp2 mutant defective in binding myosin-II does not recruit Aurora B to the cell cortex and does not promote furrow formation during monopolar cytokinesis. This mutant is also defective in maintaining the ingressing furrow during bipolar cytokinesis. Together, these findings reveal that targeting Aurora B to the cell cortex (or the equatorial cortex) by MKlp2 is essential for the maintenance of the ingressing furrow for successful cytokinesis. 相似文献
103.
Liqun Chen Guangbo Qu Xue Sun Shuping Zhang Lei Wang Nan Sang Yuguo Du Jun Liu Sijin Liu 《PloS one》2013,8(3)
Mixture toxicity is an important issue for the risk assessment of environmental pollutants, for which an extensive amount of data are necessary in evaluating their potential adverse health effects. However, it is very hard to decipher the interaction between compounds due to limited techniques. Contamination of heavy metals and organophosphoric insecticides under the environmental and biological settings poses substantial health risk to humans. Although previous studies demonstrated the co-occurrence of cadmium (Cd) and chlorpyrifos (CPF) in environmental medium and food chains, their interaction and potentially synergistic toxicity remain elusive thus far. Here we integrated the approaches of thin-layer chromatography and 1H NMR to study the interaction between Cd2+ and CPF in inducing hepatoxicity. A novel interaction was identified between Cd2+ and CPF, which might be the bonding between Cd2+ and nitrogen atom in the pyridine ring of CPF, or the chelation formation between one Cd2+ and two CPF molecules. The Cd-CPF complex was conferred with distinct biological fate and toxicological performances from its parental components. We further demonstrated that the joint hepatoxicity of Cd ion and CPF was chiefly due to the Cd-CPF complex-facilitated intracellular transport associated with oxidative stress. 相似文献
104.
Objective
Young adulthood is an important period for both bone and mental health. This study investigated the association between depressive symptoms and bone density in apparently healthy Korean men and women aged 29−32 years.Methods
This study is a cross-sectional analysis of data from 123 men and 133 women who completed follow-up examinations of the Kangwha study in 2010−2011. Bone stiffness index (SI) was measured at the os calcis using a quantitative ultrasound device. Depressive symptoms were evaluated using the Korean version of the Beck Depression Inventory (K-BDI) and classified as normal (K-BDI <10), mild (K-BDI 10–15), and moderate to severe (K-BDI ≥16).Results
Moderate to severe depressive symptoms were prevalent among 11.4% of men and 19.6% of women. Higher K-BDI scores were significantly correlated to SI in men, before (ρ = –0.286, p = 0.001) and after (ρ = –0.228, p = 0.013) adjustment for covariates. Men with depressive symptoms tended to have a lower SI; multivariate-adjusted mean SI in men with normal, mild, and moderate to severe depressive symptoms was 104.1±3.1, 100.9±5.9, and 94.1±7.8, respectively (p for trend = 0.021). In contrast, no significant correlations were identified in women.Conclusions
Depressive symptoms were significantly associated with lower SI in men, but not in women. Further studies are necessary to evaluate the impact of depression on developing osteoporosis or osteoporotic fractures later in life. 相似文献105.
Influenza epidemics arise through the accumulation of viral genetic changes. The emergence of new virus strains coincides with a higher level of influenza-like illness (ILI), which is seen as a peak of a normal season. Monitoring the spread of an epidemic influenza in populations is a difficult and important task. Twitter is a free social networking service whose messages can improve the accuracy of forecasting models by providing early warnings of influenza outbreaks. In this study, we have examined the use of information embedded in the Hangeul Twitter stream to detect rapidly evolving public awareness or concern with respect to influenza transmission and developed regression models that can track levels of actual disease activity and predict influenza epidemics in the real world. Our prediction model using a delay mode provides not only a real-time assessment of the current influenza epidemic activity but also a significant improvement in prediction performance at the initial phase of ILI peak when prediction is of most importance. 相似文献
106.
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
107.
Sangheun Lee Beom Kyung Kim Seung Up Kim Yehyun Park Sooyun Chang Jun Yong Park Do Young Kim Sang Hoon Ahn Chae Yoon Chon Kwang-Hyub Han 《PloS one》2013,8(10)
Background
Although sorafenib is accepted as the standard of care in advanced hepatocellular carcinoma (HCC), its therapeutic benefit is marginal. Here, we aimed to compare the efficacy and safety of sorafenib monotherapy (S-M) and sorafenib-based loco-regional treatments (S-LRTs) in advanced HCC.Methods
From 2007 to 2012, 290 patients with advanced HCC (Barcelona Clinic Liver Cancer stage C) with S-M (n = 226) or S-LRTs (n = 64) were reviewed retrospectively. Survival outcomes and treatment-related toxicities between two groups were analyzed.Results
Variables related to tumor burden and liver function were similar between the groups (all P > 0.05). Within the entire population, the S-LRTs group had both longer median overall survival (OS) (8.5 vs 5.5 months, P = 0.001) and progression-free survival (PFS) (5.3 vs 3.0 months, P = 0.002) than the S-M group. Furthermore, the S-LRTs group had longer Os than the S-M group in a subgroup with neither extrahepatic spread (EHS) nor regional nodal involvement (RNI) (18.0 vs 7.8 months, P = 0.019) and in a subgroup with EHS and/or RNI (8.3 vs 4.8 months, P = 0.028). In addition, the S-LRTs group had longer PFS than the S-M group in the subgroup with neither EHS nor RNI (9.6 vs 3.2 months, P = 0.027).Treatment
Related toxicity was similar between two groups.Conclusion
Combined use of sorafenib and LRTs may provide better treatment outcomes without significantly increasing treatment-related toxicities, even in patients with EHS and/or RNI. Therefore, addition of active LRTs might be considered, if feasible. 相似文献108.
Ok Yeon Jeong You Hee Sang Lee Song Hee Sung Ho Joong Kang Hee-Gyoo Hyun Sung Hee 《Indian journal of microbiology》2020,60(2):206-213
Indian Journal of Microbiology - For bacteria sampling studies, various collection methods have been used to identify bacteria. To obtain accurate information about bacteria, high quality samples... 相似文献
109.
Hong Sung Hyun Singh Sudhir Tripathi Bhumi Nath Mondal Suvendu Lee Sangmin Jung Hyun Suk Cho Chuloh Kaur Shubhpreet Kim Jin-Hong Lee Sungbeom Bai Hyoung-Woo Bae Hyeun-Jong Lee Sang Yeol Lee Seung Sik Chung Byung Yeoup 《Protoplasma》2020,257(3):807-817
Protoplasma - Alkyl hydroperoxide reductase subunit F (AhpF) is a well-known flavoprotein that transfers electrons from pyridine nucleotides to the peroxidase protein AhpC via redox-active... 相似文献
110.
We participated in CARPI rounds 38-45 both as a server predictor and a human predictor. These CAPRI rounds provided excellent opportunities for testing prediction methods for three classes of protein interactions, that is, protein-protein, protein-peptide, and protein-oligosaccharide interactions. Both template-based methods (GalaxyTBM for monomer protein, GalaxyHomomer for homo-oligomer protein, GalaxyPepDock for protein-peptide complex) and ab initio docking methods (GalaxyTongDock and GalaxyPPDock for protein oligomer, GalaxyPepDock-ab-initio for protein-peptide complex, GalaxyDock2 and Galaxy7TM for protein-oligosaccharide complex) have been tested. Template-based methods depend heavily on the availability of proper templates and template-target similarity, and template-target difference is responsible for inaccuracy of template-based models. Inaccurate template-based models could be improved by our structure refinement and loop modeling methods based on physics-based energy optimization (GalaxyRefineComplex and GalaxyLoop) for several CAPRI targets. Current ab initio docking methods require accurate protein structures as input. Small conformational changes from input structure could be accounted for by our docking methods, producing one of the best models for several CAPRI targets. However, predicting large conformational changes involving protein backbone is still challenging, and full exploration of physics-based methods for such problems is still to come. 相似文献