全文获取类型
收费全文 | 48863篇 |
免费 | 3110篇 |
国内免费 | 237篇 |
专业分类
耳鼻咽喉 | 500篇 |
儿科学 | 921篇 |
妇产科学 | 623篇 |
基础医学 | 6404篇 |
口腔科学 | 1078篇 |
临床医学 | 5154篇 |
内科学 | 10799篇 |
皮肤病学 | 988篇 |
神经病学 | 5613篇 |
特种医学 | 2493篇 |
外科学 | 8206篇 |
综合类 | 295篇 |
一般理论 | 13篇 |
预防医学 | 2237篇 |
眼科学 | 642篇 |
药学 | 2928篇 |
中国医学 | 69篇 |
肿瘤学 | 3247篇 |
出版年
2023年 | 407篇 |
2022年 | 577篇 |
2021年 | 1412篇 |
2020年 | 842篇 |
2019年 | 1267篇 |
2018年 | 1433篇 |
2017年 | 1122篇 |
2016年 | 1343篇 |
2015年 | 1553篇 |
2014年 | 1964篇 |
2013年 | 2422篇 |
2012年 | 3896篇 |
2011年 | 3929篇 |
2010年 | 2335篇 |
2009年 | 2103篇 |
2008年 | 3356篇 |
2007年 | 3434篇 |
2006年 | 3168篇 |
2005年 | 3124篇 |
2004年 | 2767篇 |
2003年 | 2641篇 |
2002年 | 2381篇 |
2001年 | 442篇 |
2000年 | 344篇 |
1999年 | 397篇 |
1998年 | 479篇 |
1997年 | 362篇 |
1996年 | 287篇 |
1995年 | 221篇 |
1994年 | 221篇 |
1993年 | 165篇 |
1992年 | 141篇 |
1991年 | 133篇 |
1990年 | 97篇 |
1989年 | 90篇 |
1988年 | 95篇 |
1987年 | 61篇 |
1986年 | 72篇 |
1985年 | 69篇 |
1984年 | 102篇 |
1983年 | 80篇 |
1982年 | 75篇 |
1981年 | 57篇 |
1980年 | 55篇 |
1979年 | 48篇 |
1978年 | 47篇 |
1977年 | 50篇 |
1976年 | 46篇 |
1975年 | 47篇 |
1974年 | 47篇 |
排序方式: 共有10000条查询结果,搜索用时 921 毫秒
991.
Martin Schmid Helga Prettenthaler Christian Weger Karl-Heinz Smolle 《Computers in biology and medicine》2013,43(10):1583-1589
In mechanically ventilated patients, Pulse Pressure Variation (PPV) has been shown to be a useful parameter to guide fluid management. We evaluated a real-time automated PPV-algorithm by comparing it to manually calculated PPV-values. In 10 critically ill patients, blood pressure was measured invasively (IBP) and non-invasively (CNAP® Monitor, CNSystems Medizintechnik, Austria). PPV was determined manually and compared to automated PPV values: PPVmanIBP vs. PPVautoIBP was ?0.19±1.65% (mean bias±standard deviation), PPVmanCNAP vs. PPVautoCNAP was ?1.02±2.03% and PPVautoCNAP vs. PPVmanIBP was ?2.10±3.14%, suggesting that the automated CNAP® PPV-algorithm works well on both blood pressure waveforms but needs further clinical evaluation. 相似文献
992.
Thomas H. Grandy Markus Werkle‐Bergner Christian Chicherio Florian Schmiedek Martin Lövdén Ulman Lindenberger 《Psychophysiology》2013,50(6):570-582
The individual alpha frequency (IAF) of the human EEG reflects systemic properties of the brain, is highly heritable, and relates to cognitive functioning. Not much is known about the modifiability of IAF by cognitive interventions. We report analyses of resting EEG from a large‐scale training study in which healthy younger (20–31 years, N = 30) and older (65–80 years, N = 28) adults practiced 12 cognitive tasks for ~100 1‐h sessions. EEG was recorded before and after the cognitive training intervention. In both age groups, IAF (and, in a control analysis, alpha amplitude) did not change, despite large gains in cognitive performance. As within‐session reliability and test‐retest stability were high for both age groups, imprecise measurements cannot account for the findings. In sum, IAF is highly stable in healthy adults up to 80 years, not easily modifiable by cognitive interventions alone, and thus qualifies as a stable neurophysiological trait marker. 相似文献
993.
Harry Sokol Sophie Georgin-Lavialle Danielle Canioni Stéphane Barete Gandhi Damaj Erinn Soucie Julie Bruneau Marie-Olivia Chandesris Felipe Suarez Jean-Marie Launay Achille Aouba Catherine Grandpeix-Guyodo Fanny Lanternier Bernard Grosbois Christian de Gennes Pascal Cathébras Olivier Fain Nadia Hoyeau-Idrissi Patrice Dubreuil Olivier Lortholary Laurent Beaugerie Brigitte Ranque Olivier Hermine 《The Journal of allergy and clinical immunology》2013
994.
Sean P. Saunders Christabelle S.M. Goh Sara J. Brown Colin N.A. Palmer Rebecca M. Porter Christian Cole Linda E. Campbell Marek Gierlinski Geoffrey J. Barton Georg Schneider Allan Balmain Alan R. Prescott Stephan Weidinger Hansjörg Baurecht Michael Kabesch Christian Gieger Young-Ae Lee Roger Tavendale Somnath Mukhopadhyay Stephen W. Turner Vishnu B. Madhok Frank M. Sullivan Caroline Relton John Burn Simon Meggitt Catherine H. Smith Michael A. Allen Jonathan N.W. N. Barker Nick J. Reynolds Heather J. Cordell Alan D. Irvine W.H. Irwin McLean Aileen Sandilands Padraic G. Fallon 《The Journal of allergy and clinical immunology》2013
995.
Christian Massire Daelynn R. Buelow Sean X. Zhang Robert Lovari Heather E. Matthews Donna M. Toleno Raymond R. Ranken Thomas A. Hall David Metzgar Rangarajan Sampath Lawrence B. Blyn David J. Ecker Zhengming Gu Thomas J. Walsh Randall T. Hayden 《Journal of clinical microbiology》2013,51(3):959-966
Invasive fungal infections are a significant cause of morbidity and mortality among immunocompromised patients. Early and accurate identification of these pathogens is central to direct therapy and to improve overall outcome. PCR coupled with electrospray ionization mass spectrometry (PCR/ESI-MS) was evaluated as a novel means for identification of fungal pathogens. Using a database grounded by 60 ATCC reference strains, a total of 394 clinical fungal isolates (264 molds and 130 yeasts) were analyzed by PCR/ESI-MS; results were compared to phenotypic identification, and discrepant results were sequence confirmed. PCR/ESI-MS identified 81.4% of molds to either the genus or species level, with concordance rates of 89.7% and 87.4%, respectively, to phenotypic identification. Likewise, PCR/ESI-MS was able to identify 98.4% of yeasts to either the genus or species level, agreeing with 100% of phenotypic results at both the genus and species level. PCR/ESI-MS performed best with Aspergillus and Candida isolates, generating species-level identification in 94.4% and 99.2% of isolates, respectively. PCR/ESI-MS is a promising new technology for broad-range detection and identification of medically important fungal pathogens that cause invasive mycoses. 相似文献
996.
Christian Pou Rocío Bellido Maria Casadellà Teresa Puig Bonaventura Clotet Richard Harrigan Roger Paredes 《Journal of clinical microbiology》2013,51(8):2754-2757
Standardization of sequence chromatogram analysis is required for consistent genotypic tropism determination across laboratories. A freely available, fast, and automated chromatogram analysis tool (RECall) provided tropism interpretations equivalent to those of manual sequence editing of 521 V3 loop HIV-1 population sequences, suggesting that RECall can be useful in standardizing genotypic tropism testing across laboratories. 相似文献
997.
Nicole Brazda Christian Voss Veronica Estrada Homaira Lodin Nils Weinrich Klaus Seide Jörg Müller Hans W. Müller 《Biomaterials》2013
Complete transection of the spinal cord leaves a gap of several mm which fills with fibrous scar tissue. Several approaches in rodent models have used tubes, foams, matrices or tissue implants to bridge this gap. Here, we describe a mechanical microconnector system (mMS) to re-adjust the retracted spinal cord stumps. The mMS is a multi-channel system of polymethylmethacrylate (PMMA), designed to fit into the spinal cord tissue gap after transection, with an outlet tubing system to apply negative pressure to the mMS thus sucking the spinal cord stumps into the honeycomb-structured holes. The stumps adhere to the microstructure of the mMS walls and remain in the mMS after removal of the vacuum. We show that the mMS preserves tissue integrity and allows axonal regrowth at 2, 5 and 19 weeks post lesion with no adverse tissue effects like in-bleeding or cyst formation. Preliminary assessment of locomotor function in the open field suggested beneficial effects of the mMS. Additional inner micro-channels enable local substance delivery into the lesion center via an attached osmotic minipump. We suggest that the mMS is a suitable device to adapt and stabilize the injured spinal cord after surgical resection of scar tissue (e.g., for chronic patients) or traumatic injuries with large tissue and bone damages. 相似文献
998.
Viola Oertel-Knöchel Britta Reinke Richard Feddern Annika Knake Christian Knöchel David Prvulovic Fabian Fußer Tarik Karakaya Deborah Loellgen Christine Freitag Johannes Pantel David E.J. Linden 《Journal of affective disorders》2013
Background
Episodic memory deficits affect the majority of patients with bipolar disorder (BD).Aims
The study investigates episodic memory performance through different approaches, including behavioural measures, physiological parameters, and the underlying functional activation patterns with functional neuroimaging (fMRI).Methods
26 Remitted BD patients and a matched group of healthy controls underwent a verbal episodic memory test together with monitored autonomic response, psychopathological ratings and functional magnetic resonance imaging (fMRI) during the verbal episodic memory test.Results
Compared to healthy controls, BD patients performed significantly worse during the episodic memory task. The results further indicate that verbal episodic memory deficits in BD are associated with abnormal functional activity patterns in frontal, occipital and limbic regions, and an increase in stress parameters.Limitations
We aimed to minimise sample heterogeneity by setting clear criteria for remission, based on the scores of a depression (BDI II) and mania scale (BRMAS) and on the DSM IV criteria. However, our patients were not symptom-free and scored higher on BDI II scores than the control group.Conclusions
The results are of interest for the treatment of cognitive symptoms in BD patients, as persistent cognitive impairment may hamper full rehabilitation. 相似文献999.
Dreaming occurs during non-rapid eye movement (NREM) and rapid eye movement (REM) sleep, which both are regulated by homeostatic, ultradian, and circadian processes. However, the magnitude of how ultradian REM and NREM sleep and its EEG correlates impact onto dream recall remains fairly unknown. In this review, we address three questions: 1. Is there an ultradian NREM–REM sleep modulation in successful dream recall, which is gated by the circadian clock? 2. What are the key electrophysiological correlates that account for dream recall during NREM and REM sleep and 3. Are there age-related changes in the ultradian and circadian regulation in dream recall and its electrophysiological correlates? Knowledge on the specific frequency and topography NREM and REM sleep differences prior to dream recall may pinpoint to the cerebral correlates that account for this cognitive process, and hint to their possible physiological meaning. 相似文献
1000.
ABSTRACTIn previous studies we have shown that a group of individuals with developmental prosopagnosia (DP): (i) were impaired at recognizing objects when presented as silhouettes or fragmented forms; stimuli which place particular demands on global shape processing, (ii) that these impairments correlated with their face recognition deficit, (iii) that they showed a reduced global precedence effect in Navon’s paradigm, and (iv) that the magnitude of their global precedence effect correlated with their face and object recognition performance. This pattern of deficits points towards a delay in the processing of global shape information; a delay that may weaken top-down influences on recognition performance. Here we show that the DPs show reduced real object superiority effects (faster responses to real objects than nonobjects) compared with controls. Given that real object superiority effects reflect top-down processing, these findings support the notion of impaired global shape based top-down processing in DP. 相似文献