全文获取类型
收费全文 | 8094篇 |
免费 | 484篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 64篇 |
儿科学 | 229篇 |
妇产科学 | 174篇 |
基础医学 | 1052篇 |
口腔科学 | 762篇 |
临床医学 | 610篇 |
内科学 | 1840篇 |
皮肤病学 | 204篇 |
神经病学 | 746篇 |
特种医学 | 164篇 |
外科学 | 1036篇 |
综合类 | 48篇 |
预防医学 | 771篇 |
眼科学 | 80篇 |
药学 | 439篇 |
中国医学 | 55篇 |
肿瘤学 | 326篇 |
出版年
2023年 | 62篇 |
2022年 | 150篇 |
2021年 | 257篇 |
2020年 | 162篇 |
2019年 | 274篇 |
2018年 | 308篇 |
2017年 | 218篇 |
2016年 | 215篇 |
2015年 | 264篇 |
2014年 | 342篇 |
2013年 | 394篇 |
2012年 | 635篇 |
2011年 | 660篇 |
2010年 | 361篇 |
2009年 | 287篇 |
2008年 | 517篇 |
2007年 | 495篇 |
2006年 | 417篇 |
2005年 | 407篇 |
2004年 | 297篇 |
2003年 | 286篇 |
2002年 | 286篇 |
2001年 | 174篇 |
2000年 | 163篇 |
1999年 | 129篇 |
1998年 | 40篇 |
1997年 | 29篇 |
1996年 | 21篇 |
1995年 | 18篇 |
1994年 | 28篇 |
1993年 | 21篇 |
1992年 | 66篇 |
1991年 | 58篇 |
1990年 | 51篇 |
1989年 | 45篇 |
1988年 | 44篇 |
1987年 | 43篇 |
1986年 | 38篇 |
1985年 | 46篇 |
1984年 | 27篇 |
1982年 | 15篇 |
1979年 | 27篇 |
1978年 | 12篇 |
1977年 | 17篇 |
1976年 | 21篇 |
1975年 | 15篇 |
1973年 | 14篇 |
1970年 | 15篇 |
1969年 | 17篇 |
1968年 | 20篇 |
排序方式: 共有8600条查询结果,搜索用时 0 毫秒
91.
92.
93.
Epidural spinal cord stimulation plus quipazine administration enable stepping in complete spinal adult rats 总被引:1,自引:0,他引:1
Gerasimenko YP Ichiyama RM Lavrov IA Courtine G Cai L Zhong H Roy RR Edgerton VR 《Journal of neurophysiology》2007,98(5):2525-2536
We hypothesized that epidural spinal cord stimulation (ES) and quipazine (a serotonergic agonist) modulates the excitability of flexor and extensor related intraspinal neural networks in qualitatively unique, but complementary, ways to facilitate locomotion in spinal cord-injured rats. To test this hypothesis, we stimulated (40 Hz) the S(1) spinal segment before and after quipazine administration (0.3 mg/kg, ip) in bipedally step-trained and nontrained, adult, complete spinal (mid-thoracic) rats. The stepping pattern of these rats was compared with control rats. At the stimulation levels used, stepping was elicited only when the hindlimbs were placed on a moving treadmill. In nontrained rats, the stepping induced by ES and quipazine administration was non-weight bearing, and the cycle period was shorter than in controls. In contrast, the stepping induced by ES and quipazine in step-trained rats was highly coordinated with clear plantar foot placement and partial weight bearing. The effect of ES and quipazine on EMG burst amplitude and duration was greater in flexor than extensor motor pools. Using fast Fourier transformation analysis of EMG bursts during ES, we observed one dominant peak at 40 Hz in the medial gastrocnemius (ankle extensor), whereas there was less of dominant spectral peak in the tibialis anterior (ankle flexor). We suggest that these frequency distributions reflect amplitude modulation of predominantly monosynaptic potentials in the extensor and predominantly polysynaptic pathways in the flexor muscle. Quipazine potentiated the amplitude of these responses. The data suggest that there are fundamental differences in the circuitry that generates flexion and extension during locomotion. 相似文献
94.
Hui Yu Zhengming Chen Karla V. Ballman Mark A. Watson Ramaswamy Govindan Irena Lanc David G. Beer Raphael Bueno Lucian R. Chirieac Michael Herman Chui Guoan Chen Wilbur A. Franklin David R. Gandara Carlo Genova Kristine A. Brovsky Mary-Beth M. Joshi Daniel T. Merrick William G. Richards Fred R. Hirsch 《Journal of thoracic oncology》2019,14(1):25-36
Objectives
Anti–programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) immunotherapy has demonstrated success in the treatment of advanced NSCLC. Recently, PD-1/PD-L1 blockade also has demonstrated interesting results in small trials of neoadjuvant treatment in stage IB to IIIA NSCLC. In addition, several clinical trials using anti–PD-1/PD-L1 immunotherapy as an adjuvant or neoadjuvant treatment in patients with resectable stage NSCLC are ongoing. However, few analyses of anti–PD-1/PD-L1 immunotherapy–related biomarkers in early-stage squamous cell lung carcinoma (SqCLC) have been reported. In this study, we evaluated PD-L1 protein expression, tumor mutation burden, and expression of an immune gene signature in early-stage SqCLC, providing data for identifying the potential role for patients with anti–PD-1/PD-L1 treatment in early-stage SqCLC.Methods
A total of 255 specimens from patients with early-stage SqCLC were identified within participating centers of the Strategic Partnering to Evaluate Cancer Signatures program. PD-L1 protein expression by immunohistochemistry was evaluated by using the Dako PD-L1 22C3 pharmDx kit on the Dako Link 48 auto-stainer (Dako, Carpinteria, CA). Tumor mutation burden (TMB) was calculated on the basis of data from targeted genome sequencing. The T-effector and interferon gamma (IFN-γ) gene signature was determined from Affymetrix gene chip data (Affymetrix, Santa Clara, CA) from frozen specimens.Results
The prevalence of PD-L1 expression was 9.8% at a tumor proportion score cutoff of at least 50%. PD-L1 mRNA and programmed cell death 1 ligand 2 mRNA positively correlated with PD-L1 protein expression on tumor cells (TCs) and tumor-infiltrating immune cells. PD-L1 protein expression on tumor-infiltrating immune cells was correlated with the T-effector and IFN-γ gene signature (p < 0.001), but not with TMB. For TCs, all of these biomarkers were independent of each other and neither PD-L1 protein expression, TMB, or T-effector and IFN-γ gene signatures were independently prognostic for patient outcomes.Conclusions
Evaluation of PD-L1 expression, TMB, and T-effector and IFN-γ gene signatures in the cohort with early-stage SqCLC found them to be independent of each other, and none was associated with overall survival. Our results also support the hypothesis that PD-L1 expression is regulated by an intrinsic mechanism on TCs and an adaptive mechanism on immune cells. 相似文献95.
Rita González Valerio Carmen Salvador BalladaMaría Gómez Valdemoro Gregorio Manzanera Bueno 《Progresos de Obstetricia y Ginecología》2009
Nowadays, twin gestation is increased due to advances in assisted reproduction. Unquestionably, these pregnancies have an increased risk of foetal and maternal disorders. Single foetal death has a different incidence depending on gestational age; in the first trimester between 10-70%, in the second and third trimester it is a rare event, 0.5-7%. 相似文献
96.
97.
José Wellington Alves dos Santos Fabiani Palagi Machado Felipe Schaich Douglas Zaione Nascimento Tiago Teixeira Simon Luis Fernando Cibin Keli Cristina Mann Vinícius André Guerra Mateus Correa Marcos Ferreira Gazzoni Marta Pires da Rocha Melissa Daubermann Falster Ronaldo Manfredini Vassoler 《Respiratory Medicine Extra》2007,3(4):186-188
98.
99.
Reis AD Fink MC Machado CM Paz Jde P Oliveira RR Tateno AF Machado AF Cardoso MR Pannuti CS;CHIADO RDGV/FAPESP Research Groups 《Revista do Instituto de Medicina Tropical de S?o Paulo》2008,50(1):37-40
A total of 316 samples of nasopharyngeal aspirate from infants up to two years of age with acute respiratory-tract illnesses were processed for detection of respiratory syncytial virus (RSV) using three different techniques: viral isolation, direct immunofluorescence, and PCR. Of the samples, 36 (11.4%) were positive for RSV, considering the three techniques. PCR was the most sensitive technique, providing positive findings in 35/316 (11.1%) of the samples, followed by direct immunofluorescence (25/316, 7.9%) and viral isolation (20/315, 6.3%) (p < 0.001). A sample was positive by immunofluorescence and negative by PCR, and 11 (31.4%) were positive only by RT-PCR. We conclude that RT-PCR is more sensitive than IF and viral isolation to detect RSV in nasopharyngeal aspirate specimens in newborn and infants. 相似文献
100.
Aumento de Óbitos Domiciliares devido a Parada Cardiorrespiratória em Tempos de Pandemia de COVID-19
Nathalia Sernizon Guimares Taciana Malheiros Lima Carvalho Jackson Machado-Pinto Roger Lage Renata Mascarenhas Bernardes Alex Sander Sena Peres Mariana Amaral Raposo Ricardo Machado Carvalhais Renan Avelino Mancini Gabriella Yuka Shiomatsu Bruna Carvalho Oliveira Valria de Melo Rodrigues Maria do Carmo Barros de Melo Unaí Tupinambs 《Arquivos brasileiros de cardiologia》2021,116(2):266
BackgroundCardiovascular diseases constitute an important group of causes of death in the country. Ischemic heart diseases that are the main causes of cardiopulmonary arrest, leading to an impact on the mortality of the cardiovascular diseases in the health system.ObjectiveAssess the number of home deaths by cardiopulmonary arrest notified by the Mobile Emergency Medical Service (SAMU) in March 2018, 2019 and 2020.MethodsObservational study carried out from the analysis of cardiopulmonary arrest mortality data of citizens assisted by SAMU in Belo Horizonte, Minas Gerais, Brazil. Social and clinical characteristics and occurrence information of the patients were analyzed. The mortality rate due to cardiopulmonary arrest in relation to the total number of attendances was assessed. A significance level of 95% was considered.ResultsThere was increase of home deaths due to cardiopulmonary arrest in March 2020 compared to March 2018 (p<0.001) and March 2019 (p=0.050). Of the deaths reported in 2020, 63.8% of the patients were aged 60 years or older, 63.7% of the occurrences were performed in the afternoon and approximately 87% of the cardiopulmonary arrest notified had associated clinical comorbidities, with systemic arterial hypertension and heart failure represented by 22.87% and 13.03% of the reported cases, respectively. The majority of the evaluated sample of this study did not have any medical care follow-up (88.7%).ConclusionConsidering the increase in the number of the deaths, we suggest reflections and readjustments regarding the monitoring of chronic non-transmissible diseases during a pandemic, as well as improvements in death surveillance. (Arq Bras Cardiol. 2021; 116(2):266-271) 相似文献