全文获取类型
收费全文 | 6900篇 |
免费 | 521篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 49篇 |
儿科学 | 241篇 |
妇产科学 | 161篇 |
基础医学 | 956篇 |
口腔科学 | 61篇 |
临床医学 | 805篇 |
内科学 | 1402篇 |
皮肤病学 | 113篇 |
神经病学 | 664篇 |
特种医学 | 168篇 |
外科学 | 674篇 |
综合类 | 81篇 |
一般理论 | 11篇 |
预防医学 | 800篇 |
眼科学 | 267篇 |
药学 | 442篇 |
中国医学 | 14篇 |
肿瘤学 | 521篇 |
出版年
2024年 | 12篇 |
2023年 | 77篇 |
2022年 | 122篇 |
2021年 | 238篇 |
2020年 | 131篇 |
2019年 | 242篇 |
2018年 | 216篇 |
2017年 | 176篇 |
2016年 | 203篇 |
2015年 | 240篇 |
2014年 | 288篇 |
2013年 | 377篇 |
2012年 | 536篇 |
2011年 | 543篇 |
2010年 | 291篇 |
2009年 | 230篇 |
2008年 | 427篇 |
2007年 | 421篇 |
2006年 | 407篇 |
2005年 | 385篇 |
2004年 | 330篇 |
2003年 | 345篇 |
2002年 | 284篇 |
2001年 | 85篇 |
2000年 | 65篇 |
1999年 | 74篇 |
1998年 | 46篇 |
1997年 | 58篇 |
1996年 | 29篇 |
1995年 | 39篇 |
1994年 | 29篇 |
1993年 | 29篇 |
1992年 | 36篇 |
1991年 | 22篇 |
1990年 | 28篇 |
1989年 | 31篇 |
1988年 | 11篇 |
1987年 | 23篇 |
1986年 | 25篇 |
1985年 | 18篇 |
1984年 | 18篇 |
1983年 | 19篇 |
1982年 | 20篇 |
1980年 | 14篇 |
1978年 | 15篇 |
1977年 | 10篇 |
1975年 | 11篇 |
1973年 | 13篇 |
1972年 | 18篇 |
1971年 | 11篇 |
排序方式: 共有7430条查询结果,搜索用时 15 毫秒
51.
Cerebrovascular responses to somatomotor stimulation in Parkinson’s disease: A multivariate analysis
Sam C Barnes Ronney B Panerai Lucy Beishon Martha Hanby Thompson G Robinson Victoria J Haunton 《Journal of cerebral blood flow and metabolism》2022,42(8):1547
Parkinson’s disease (PD) is a common neurodegenerative disorder, yet little is known about cerebral haemodynamics in this patient population. Previous studies assessing dynamic cerebral autoregulation (dCA), neurovascular coupling (NVC) and vasomotor reactivity (VMR) have yielded conflicting findings. By using multi-variate modelling, we aimed to determine whether cerebral blood flow (CBF) regulation is impaired in PD patients.55 healthy controls (HC) and 49 PD patients were recruited. PD subjects underwent a second recording following a period of abstinence from their anti-Parkinsonian medication. Continuous bilateral transcranial Doppler in the middle cerebral arteries, beat-to-beat mean arterial blood pressure (MAP; Finapres), heart rate (HR; electrocardiogram), and end-tidal CO2 (EtCO2; capnography) were measured. After a 5-min baseline period, a passive motor paradigm comprising 60 s of elbow flexion was performed. Multi-variate modelling quantified the contributions of MAP, ETCO2 and neural stimulation to changes in CBF velocity (CBFV). dCA, VMR and NVC were quantified to assess the integrity of CBF regulation.Neural stimulation was the dominant input. dCA, NVC and VMR were all found to be impaired in the PD population relative to HC (p < 0.01, p = 0.04, p < 0.01, respectively). Our data suggest PD may be associated with depressed CBF regulation. This warrants further assessment using different neural stimuli. 相似文献
52.
53.
The molecular mechanism of carboplatin [cis-1,1-cyclobutanedicarboxylatodiammineplatinum(II)] activation is still unresolved. We studied the binding of carboplatin to calf thymus DNA in the presence of thiourea, glutathione, and human breast cancer MCF-7 cell cytoplasmic extracts by measurement of DNA-dependent ethidium bromide fluorescence and atomic absorption spectroscopy. After a 96-hr period of reaction, the decrease in the DNA-dependent fluorescence yield of ethidium bromide due to the formation of platinum (Pt)-DNA adducts increased significantly in the presence of thiourea (6-fold) and glutathione (3- to 4-fold) as compared to the controls in the absence of the nucleophiles. There was also a marked elevation in the levels of platinum incorporated into DNA, measured by atomic absorption spectroscopy (2- to 3-fold and 5- to 7-fold for thiourea and glutathione, respectively). More remarkably, the Pt-DNA adducts formed in the presence of cytoplasmic extracts of MCF-7 human breast cancer cells also showed similar results in a dose-related fashion. Carboplatin, therefore, displayed a characteristic increase in DNA binding/damaging in the presence of the very same S-containing nucleophiles that showed the expected quenching effects in the case of cisplatin [cis-diamminedichloroplatinum (II)]. We propose a nucleophile-facilitated release of the active species of carboplatin prior to binding with DNA. 相似文献
54.
55.
OBJECTIVE: To evaluate the need for initial inpatient treatment for patients being treated with low-dose intramuscular methotrexate for low-risk gestational trophoblastic neoplasia (GTN). STUDY DESIGN: Clinical notes of all patients treated with low-dose intramuscular methotrexate for low-risk GTN were analyzed and side effects noted. RESULTS: There were no episodes of increased uterine bleeding requiring extra medical intervention. There were 7 cases of chest pain; none required a change from methotrexate chemotherapy. CONCLUSION: Patients being treated with low-dose intramuscular methotrexate for low-risk GTN do not need to be treated routinely in the hospital for their first treatment cycle. 相似文献
56.
Diana Erazo Maria F. Vincenti-Gonzalez Joris A. F. van Loenhout Pierre Hubin Mathil Vandromme Piet Maes Maxime Taquet Johan Van Weyenbergh Lucy Catteau Simon Dellicour 《Viruses》2022,14(6)
The national vaccination campaign against SARS-CoV-2 started in January 2021 in Belgium. In the present study, we aimed to use national hospitalisation surveillance data to investigate the recent evolution of vaccine impact on the risk of COVID-19 hospitalisation. We analysed aggregated data from 27,608 COVID-19 patients hospitalised between October 2021 and February 2022, stratified by age category and vaccination status. For each period, vaccination status, and age group, we estimated risk ratios (RR) corresponding to the ratio between the probability of being hospitalised following SARS-CoV-2 infection if belonging to the vaccinated population and the same probability if belonging to the unvaccinated population. In October 2021, a relatively high RR was estimated for vaccinated people > 75 years old, possibly reflecting waning immunity within this group, which was vaccinated early in 2021 and invited to receive the booster vaccination at that time. In January 2022, a RR increase was observed in all age categories coinciding with the dominance of the Omicron variant. Despite the absence of control for factors like comorbidities, previous infections, or time since the last administered vaccine, we showed that such real-time aggregated data make it possible to approximate trends in vaccine impact over time. 相似文献
57.
58.
Chinwe Lucy Marchie 《亚太生殖杂志》2012,1(4):315-317
ObjectiveTo investigate the socio-cultural factors that contribute to Maternal Mortality in Edo South Senatorial District.MethodsThe population of the study was made up of 2 157 females of reproductive age and multi-stage random sampling technique was used. The instrument for data collection was a self developed structured and validated questionnaire with a reliability of 0.82. Focus group discussion (FGD) and in-depth interview guide were employed to complement the instrument. Inferential statistics of multiple regressions were also employed to test the hypotheses at 0.05 level of significance.ResultsThe results showed that the socio-cultural variables when taken together contributed positively to maternal mortality [R2 = 0.32; CV = 16.5; df = 7). The finding further revealed that six, out of seven of the independent variables in the study significantly contributed to maternal mortality in Edo South Senatorial District. The implications of these findings in maternal and child health care were highlighted.ConclusionsThe study had shown that in addition to medical causes of maternal mortality, there are socio-cultural factors that contribute to women dying during pregnancy, labour and pueperium. 相似文献
59.
60.
Mary E. Reid Anna J. Duffield-Lillico Elizabeth Slate Nachimuthu Natarajan Bruce Turnbull Elizabeth Jacobs 《Nutrition and cancer》2013,65(2):155-163
Nonexperimental studies suggest that individuals with higher selenium (Se) status are at decreased risk of cancer. The Nutritional Prevention of Cancer (NPC) study randomized 1,312 high-risk dermatology patients to 200-mcg/day of Se in selenized yeast or a matched placebo; selenium supplementation decreased the risk of lung, colon, prostate, and total cancers but increased the risk of nonmelanoma skin cancer. In this article, we report on a small substudy in Macon, GA, which began in 1989 and randomized 424 patients to 400-mcg/day of Se or to matched placebo. The subjects from both arms had similar baseline Se levels to those treated by 200 mcg, and those treated with 400-mcg attained plasma Se levels much higher than subjects treated with 200 mcg. The 200-mcg/day Se treatment decreased total cancer incidence by a statistically significant 25%; however, 400-mcg/day of Se had no effect on total cancer incidence. 相似文献