全文获取类型
收费全文 | 6100篇 |
免费 | 283篇 |
国内免费 | 230篇 |
专业分类
6613篇 |
出版年
2024年 | 10篇 |
2023年 | 93篇 |
2022年 | 147篇 |
2021年 | 157篇 |
2020年 | 164篇 |
2019年 | 202篇 |
2018年 | 184篇 |
2017年 | 136篇 |
2016年 | 151篇 |
2015年 | 216篇 |
2014年 | 299篇 |
2013年 | 469篇 |
2012年 | 241篇 |
2011年 | 235篇 |
2010年 | 218篇 |
2009年 | 296篇 |
2008年 | 302篇 |
2007年 | 315篇 |
2006年 | 323篇 |
2005年 | 304篇 |
2004年 | 262篇 |
2003年 | 234篇 |
2002年 | 222篇 |
2001年 | 159篇 |
2000年 | 114篇 |
1999年 | 115篇 |
1998年 | 122篇 |
1997年 | 100篇 |
1996年 | 103篇 |
1995年 | 81篇 |
1994年 | 88篇 |
1993年 | 88篇 |
1992年 | 68篇 |
1991年 | 80篇 |
1990年 | 53篇 |
1989年 | 39篇 |
1988年 | 29篇 |
1987年 | 40篇 |
1986年 | 20篇 |
1985年 | 21篇 |
1984年 | 29篇 |
1983年 | 12篇 |
1982年 | 20篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 16篇 |
1978年 | 4篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有6613条查询结果,搜索用时 15 毫秒
991.
992.
993.
Rafael Bielza Galindo Jesús Llorente Gutiérrez José Luis Pérez González Asunción Mora Casado David Blanco Díaz Javier Escalera Alonso Adoración Morales Fernández Cristina Molano Ortiz Beredys Esmirla García López Nazaret del Amo del Arco Juan Pablo Barro Ordovas Estefanía Arias Muñana Marta Neira Álvarez David Sanz Rosa Jorge Fco. Gómez Cerezo 《Revista espa?ola de geriatría y gerontología》2018,53(1):38-44
Introduction
There are no previous studies evaluating the effect of intravenous iron therapy on functional and cognitive status of patients with hip fracture (HF).Material and methods
A single-centre randomised, placebo-controlled, double-blind and parallel treatment, clinical trial has been designed to assess the efficacy of intravenous iron therapy during the peri-operative period in elderly patients suffering from a HF. Blinding will be ensured by the packaging of the drug infusion system. On days 1, 3, and 5 from admission, the intervention group will receive 200 mg Venofer® (iron sucrose) diluted in 100 ml saline, and the control group 100 ml saline, also on days 1, 3 and 5. Patients will received conventional treatment in ortho-geriatric unit of the Hospital Infanta Sofia. Functional variables (activities of daily living and walking), cognitive (cognitive status and delirium), surgical, demographic and clinical characteristics will be collected during admission in order to assess the impact of treatment. A safety analysis of the treatment will also performed. Patients will be followed-up at 3, 6, and 12 months.Results
The study will attempt to provide evidence on the impact of the intravenous iron administration on functional recovery. It will be determined whether iron therapy negatively affects the incidence of post-operative delirium. Finally, report will be presented on the safety data of intravenous iron in elderly HF patients, as well as the impact on allogenic blood transfusion savings.Conclusions
The inclusion of elderly HF patients admitted to an ortho-geriatric unit, in a clinical trial, will help to improve the knowledge of the treatment impact on a usual scenario, and provide useful data for use in other units. 相似文献994.
995.
Feed Your Friends: Do Plant Exudates Shape the Root Microbiome? 总被引:9,自引:0,他引:9
996.
997.
Gelare Hajsalimi Saba Taheri Farshad Shahi Farnoosh Attar Hosein Ahmadi 《Journal of biomolecular structure & dynamics》2018,36(4):928-937
Nanoparticles (NPs) are one of the interesting and widely studying issues mainly because of their particular physico-chemical features and broad applications in the field of biomedical sciences, such as diagnosis and drug delivery. In this study, the interaction of iron nanoparticles (Fe–NPs) with Tau protein and PC12 cell, as potential nervous system models, was investigated with a range of techniques including dynamic light scattering, intrinsic fluorescence spectroscopy, circular dichroism, [(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium-bromid] assay, and acridine orange/ethidium bromide (AO/EB) dual staining method. An inverse correlation between Stern and Volmer constant (KSV) and temperature indicated a probable static quenching mechanism occurred between Tau protein and Fe–NPs. The number of binding site (n = 0.86) showed that there is almost one binding site of Fe–NP per protein. The negative values of ?H (?53.21 kJ/mol) and T?S (?42.44 kJ/mol) revealed that Fe–NPs interacts with Tau protein with dominate role of hydrogen bonds and van der Waals interactions and this interaction was spontaneous (?G = ?10.77 kJ/mol). Also, Fe–NPs stabilized the random coil structure of Tau protein. Moreover, Fe–NPs reduced PC12 cells viability by fragmentation of DNA in an apoptotic manner. In conclusion, induced conformational changes of Tau protein and cytotoxicity of PC12 cells by Fe–NP were revealed to be in a concentration and time-dependent manner. 相似文献
998.
Several low-molecular-weight organic carbon (LMWOC) compounds (acetate, propionate, butyrate, lactate, and glucose) were added to flooded arsenic-rich tailing mine soil to investigate their effect to the mobilization of As/Fe and potential shift of microbial community. A promoting effect to the mobilization and biotransformation of As(V)/Fe(III) in the soils resulting from the supplementation with LMWOCs substrate was indicated compared to the biotic microcosm amended with deionized water alone. During 38-day biotic incubation, more than 2100 μg/L of As(III) and 4.2 mg/L of Fe(II) levels were released from the soils amended with LMWOCs substrates, compared to the levels of As(III) and Fe(II) (less 35 μg/L and 1.82 mg/L) derived from the biotic supplementation with deionized water alone. PCR-DGGE indicated that several LMWOCs-responded bacteria were mostly related to Firmicutes and Proteobacteria. Moreover, a negligible impact on the abundance of Fe(III)-reducing family Geobacteraceae was indicated in the LMWOCs-amended soils. However, an increased abundance of sulfate-reducing bacteria but a decreased abundance of arsenate-respiring bacteria were indicated upon the soils supplemented with acetate alone, compared with other LMWOC amendments. DNA-stable isotope probing analysis demonstrated that the dual roles of acetate was not only served as an electron donor for biotransformation of As(V)/Fe(III) in soil, but also assimilated as a powerful energy source to promote the growth of sulfate-reducing bacteria. The findings suggest that there are specific bacteria that preferentially respond to the additions of LMWOC for controlling the biochemical cycle process of As/Fe in soils. 相似文献
999.
1000.
The removal of Ca2+ from the medium by intact vacuoles and microsomes of Chenopodium album was investigated by measuring INDO-1 fluorescence emission at 400 and 480 nm and the response of Ca2+ -selective mini-electrodes. The removal of Ca2+ depended on the presence of MgATP, displaying an apparent K
mATP of about 50 μM, a K
mCa of 400–500 nM, and a nucleotide specificity (%) of ATP (100) > CTP (49) > GTP (28) > UTP (20) > ADP = AMP (0). In the presence
of saturating MgATP, the vacuoles reduced the [Ca2+] of the medium below 30 nM. Part of the Ca2+ removed from the medium was released again after adding micromolar concentrations of inositol-1,4,5-trisphosphate. This release
of Ca2+ was inhibited by heparin. Since digitonin caused the release of the entire amount of Ca2+ removed from the medium in the presence of MgATP, we argue that the Ca2+ is not bound to membranes or sequestered otherwise, but is transported into the vacuoles (or vesicles) and remains freely
mobile there. In accordance with the current literature, we conclude that the plant vacuole is an important store for mobile
Ca2+ to be released for purposes of signal transduction. Since changes in the trans-tonoplast ΔpH and inhibition of the H+-translocating pumps had no significant influence on the ATP-dependent removal of Ca2+ from the cytoplasmic side, we argue that in C. album ATP-driven Ca2+ transport is the predominant form of Ca2+ translocation into the vacuole.
Received: 11 July 1996 / Accepted: 18 October 1996 相似文献