全文获取类型
收费全文 | 1857415篇 |
免费 | 135256篇 |
国内免费 | 3207篇 |
专业分类
耳鼻咽喉 | 26196篇 |
儿科学 | 61903篇 |
妇产科学 | 52480篇 |
基础医学 | 274779篇 |
口腔科学 | 52477篇 |
临床医学 | 161681篇 |
内科学 | 360840篇 |
皮肤病学 | 40142篇 |
神经病学 | 140256篇 |
特种医学 | 71500篇 |
外国民族医学 | 430篇 |
外科学 | 284953篇 |
综合类 | 39295篇 |
现状与发展 | 3篇 |
一般理论 | 450篇 |
预防医学 | 135833篇 |
眼科学 | 43142篇 |
药学 | 141841篇 |
4篇 | |
中国医学 | 4522篇 |
肿瘤学 | 103151篇 |
出版年
2018年 | 18917篇 |
2016年 | 16082篇 |
2015年 | 18258篇 |
2014年 | 25237篇 |
2013年 | 37934篇 |
2012年 | 51531篇 |
2011年 | 54686篇 |
2010年 | 32211篇 |
2009年 | 30293篇 |
2008年 | 51936篇 |
2007年 | 55908篇 |
2006年 | 56893篇 |
2005年 | 54705篇 |
2004年 | 53002篇 |
2003年 | 51102篇 |
2002年 | 49932篇 |
2001年 | 86795篇 |
2000年 | 88801篇 |
1999年 | 74681篇 |
1998年 | 20758篇 |
1997年 | 18239篇 |
1996年 | 18657篇 |
1995年 | 17627篇 |
1994年 | 16655篇 |
1993年 | 15316篇 |
1992年 | 59400篇 |
1991年 | 58507篇 |
1990年 | 57507篇 |
1989年 | 56277篇 |
1988年 | 52205篇 |
1987年 | 50780篇 |
1986年 | 48473篇 |
1985年 | 45996篇 |
1984年 | 34187篇 |
1983年 | 29476篇 |
1982年 | 17121篇 |
1981年 | 15182篇 |
1979年 | 31992篇 |
1978年 | 22451篇 |
1977年 | 19367篇 |
1976年 | 18296篇 |
1975年 | 20148篇 |
1974年 | 23703篇 |
1973年 | 22790篇 |
1972年 | 21583篇 |
1971年 | 20138篇 |
1970年 | 19025篇 |
1969年 | 18044篇 |
1968年 | 16866篇 |
1967年 | 14865篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
41.
Distribution of temperature changes and neurovascular coupling in rat brain following 3,4‐methylenedioxymethamphetamine (MDMA, “ecstasy”) exposure
下载免费PDF全文
![点击此处可从《NMR in biomedicine》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Daniel Coman Basavaraju G. Sanganahalli Lihong Jiang Fahmeed Hyder Kevin L. Behar 《NMR in biomedicine》2015,28(10):1257-1266
(+/?)3,4‐methylenedioxymethamphetamine (MDMA, “ecstasy”) is an abused psychostimulant that produces strong monoaminergic stimulation and whole‐body hyperthermia. MDMA‐induced thermogenesis involves activation of uncoupling proteins (UCPs), primarily a type specific to skeletal muscle (UCP‐3) and absent from the brain, although other UCP types are expressed in the brain (e.g. thalamus) and might contribute to thermogenesis. Since neuroimaging of brain temperature could provide insights into MDMA action, we measured spatial distributions of systemically administered MDMA‐induced temperature changes and dynamics in rat cortex and subcortex using a novel magnetic resonance method, Biosensor Imaging of Redundant Deviation in Shifts (BIRDS), with an exogenous temperature‐sensitive probe (thulium ion and macrocyclic chelate 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetramethyl‐1,4,7,10‐tetraacetate (DOTMA4?)). The MDMA‐induced temperature rise was greater in the cortex than in the subcortex (1.6 ± 0.4 °C versus 1.3 ± 0.4 °C) and occurred more rapidly (2.0 ± 0.2 °C/h versus 1.5 ± 0.2 °C/h). MDMA‐induced temperature changes and dynamics in the cortex and body were correlated, although the body temperature exceeded the cortex temperature before and after MDMA. Temperature, neuronal activity, and blood flow (CBF) were measured simultaneously in the cortex and subcortex (i.e. thalamus) to investigate possible differences of MDMA‐induced warming across brain regions. MDMA‐induced warming correlated with increases in neuronal activity and blood flow in the cortex, suggesting that the normal neurovascular response to increased neural activity was maintained. In contrast to the cortex, a biphasic relationship was seen in the subcortex (i.e. thalamus), with a decline in CBF as temperature and neural activity rose, transitioning to a rise in CBF for temperature above 37 °C, suggesting that MDMA affected CBF and neurovascular coupling differently in subcortical regions. Considering that MDMA effects on CBF and heat dissipation (as well as potential heat generation) may vary regionally, neuroprotection may require different cooling strategies. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
42.
O. Ieromina C. J. M. Musters P. M. Bodegom W. J. G. M. Peijnenburg M. G. Vijver 《Ecotoxicology (London, England)》2016,25(6):1170-1180
Analyzing functional species’ characteristics (species traits) that represent physiological, life history and morphological characteristics of species help understanding the impacts of various stressors on aquatic communities at field conditions. This research aimed to study the combined effects of pesticides and other environmental factors (temperature, dissolved oxygen, dissolved organic carbon, floating macrophytes cover, phosphate, nitrite, and nitrate) on the trait modality distribution of aquatic macrofauna communities. To this purpose, a field inventory was performed in a flower bulb growing area of the Netherlands with significant variation in pesticides pressures. Macrofauna community composition, water chemistry parameters and pesticide concentrations in ditches next to flower bulb fields were determined. Trait modalities of nine traits (feeding mode, respiration mode, locomotion type, resistance form, reproduction mode, life stage, voltinism, saprobity, maximum body size) likely to indicate pesticides impacts were analyzed. According to a redundancy analysis, phosphate -and not pesticides- constituted the main factor structuring the trait modality distribution of aquatic macrofauna. The functional composition could be ascribed for 2–4 % to pesticides, and for 3–11 % to phosphate. The lack of trait responses to pesticides may indicate that species may have used alternative strategies to adapt to ambient pesticides stress. Biomass of animals exhibiting trait modalities related to feeding by predation and grazing, presence of diapause form or dormancy, reproduction by free clutches and ovoviviparity, life stage of larvae and pupa, was negatively correlated to the concentration of phosphate. Hence, despite the high pesticide pollution in the area, variation in nutrient-related stressors seems to be the dominant driver of the functional composition of aquatic macrofauna assembly in agricultural ditches. 相似文献
43.
44.
45.
46.
47.
48.
49.
Usha Patel Manish Pandey Sadhana Kannan Tanuja A. Samant Poonam Gera Neha Mittal Swapnil Rane Asawari Patil Vanita Noronha Amit Joshi Vijay M. Patil Kumar Prabhash Manoj B. Mahimkar 《British journal of cancer》2020,123(12):1757
Background Anti-EGFR-based therapies have limited success in HNSCC patients. Predictive biomarkers are greatly needed to identify the patients likely to be benefited from these targeted therapies. Here, we present the prognostic and predictive association of biomarkers in HPV-negative locally advanced (LA) HNSCC patients.Methods Treatment-naive tumour tissue samples of 404 patients, a subset of randomised Phase 3 trial comparing cisplatin radiation (CRT) versus nimotuzumab plus cisplatin radiation (NCRT) were analysed to evaluate the expression of HIF1α, EGFR and pEGFR by immunohistochemistry and EGFR gene copy change by FISH. Progression-free survival (PFS), locoregional control (LRC) and overall survival (OS) were estimated by Kaplan–Meier method. Hazard ratios were estimated by Cox proportional hazard models.Results Baseline characteristics of the patients were balanced between two treatment groups (CRT vs NCRT) and were representative of the trial cohort. The median follow-up was of 39.13 months. Low HIF1α was associated with better PFS [HR (95% CI) = 0.62 (0.42–0.93)], LRC [HR (95% CI) = 0.56 (0.37–0.86)] and OS [HR (95% CI) = 0.63 (0.43–0.93)] in the CRT group. Multivariable analysis revealed HIF1α as an independent negative prognostic biomarker. For patients with high HIF1α, NCRT significantly improved the outcomes [PFS:HR (95% CI) = 0.55 (0.37–0.82), LRC:HR (95% CI) = 0.55 (0.36–0.85) and OS:HR (95% CI) = 0.54 (0.36–0.81)] compared to CRT. While in patients with low HIF1α, no difference in the clinical outcomes was observed between treatments. Interaction test suggested a predictive value of HIF1α for OS (P = 0.008).Conclusions High HIF1α expression is a predictor of poor clinical response to CRT in HPV-negative LA-HNSCC patients. These patients with high HIF1α significantly benefited with the addition of nimotuzumab to CRT.Clinical trial registration Registered with the Clinical Trial Registry of India (Trial registration identifier—CTRI/2014/09/004980).Subject terms: Tumour biomarkers, Head and neck cancer, Tumour biomarkers, Head and neck cancer, Predictive markers 相似文献
50.