全文获取类型
收费全文 | 236484篇 |
免费 | 26252篇 |
国内免费 | 1570篇 |
专业分类
耳鼻咽喉 | 3580篇 |
儿科学 | 7738篇 |
妇产科学 | 4058篇 |
基础医学 | 32637篇 |
口腔科学 | 8991篇 |
临床医学 | 21913篇 |
内科学 | 54861篇 |
皮肤病学 | 10091篇 |
神经病学 | 22618篇 |
特种医学 | 5462篇 |
外国民族医学 | 7篇 |
外科学 | 29459篇 |
综合类 | 5876篇 |
现状与发展 | 1篇 |
一般理论 | 57篇 |
预防医学 | 19073篇 |
眼科学 | 4675篇 |
药学 | 16650篇 |
53篇 | |
中国医学 | 3388篇 |
肿瘤学 | 13118篇 |
出版年
2024年 | 886篇 |
2023年 | 1483篇 |
2022年 | 2759篇 |
2021年 | 6403篇 |
2020年 | 7922篇 |
2019年 | 13572篇 |
2018年 | 13263篇 |
2017年 | 12305篇 |
2016年 | 12560篇 |
2015年 | 13225篇 |
2014年 | 14613篇 |
2013年 | 17055篇 |
2012年 | 15085篇 |
2011年 | 15710篇 |
2010年 | 13959篇 |
2009年 | 9934篇 |
2008年 | 11095篇 |
2007年 | 10563篇 |
2006年 | 9808篇 |
2005年 | 9330篇 |
2004年 | 8221篇 |
2003年 | 7693篇 |
2002年 | 7019篇 |
2001年 | 4578篇 |
2000年 | 4959篇 |
1999年 | 3752篇 |
1998年 | 923篇 |
1997年 | 783篇 |
1996年 | 663篇 |
1995年 | 578篇 |
1994年 | 472篇 |
1993年 | 356篇 |
1992年 | 1369篇 |
1991年 | 1128篇 |
1990年 | 1033篇 |
1989年 | 853篇 |
1988年 | 725篇 |
1987年 | 658篇 |
1986年 | 675篇 |
1985年 | 577篇 |
1984年 | 415篇 |
1983年 | 356篇 |
1979年 | 390篇 |
1978年 | 267篇 |
1974年 | 336篇 |
1973年 | 331篇 |
1972年 | 287篇 |
1971年 | 309篇 |
1970年 | 287篇 |
1969年 | 308篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Luis Alfonso Ortíz-Reyes Lilia Castillo-Martínez Arianne Itzel Lupián-Angulo Daniel Dante Yeh Héctor Isaac Rocha-González Aurora Elizabeth Serralde-Zúñiga 《Journal of the Academy of Nutrition and Dietetics》2018,118(1):52-61
Background
Unintentional underfeeding is common in patients receiving enteral nutrition (EN), and is associated with increased risk of malnutrition complications. Protocols for EN in critically ill patients have been shown to enhance adequacy, resulting in better clinical outcomes; however, outside of intensive care unit (ICU) settings, the influence of a protocol for EN is unknown.Objective
To evaluate the efficacy and safety of implementing an EN protocol in a noncritical setting.Design
Randomized controlled clinical trial.Participants and settings
This trial was conducted from 2014 to 2016 in 90 adult hospitalized patients (non-ICU) receiving exclusively EN. Patients with carcinomatosis, ICU admission, or <72 hours of EN were excluded.Intervention
The intervention group received EN according to a protocol, whereas the control group was fed according to standard practice.Main outcome measures
The proportion of patients receiving ≥80% of their caloric target at Day 4 after EN initiation.Statistical analyses performed
Student t test or Wilcoxon rank-sum test were used for continuous variables and the difference between the groups in the time to receipt of the optimal amount of nutrition was analyzed using Kaplan-Meier curves.Results
Forty-five patients were randomized to each group. At Day 4 after EN initiation, 61% of patients in the intervention arm had achieved the primary end point compared with 23% in the control group (P=0.001). In malnourished patients, 63% achieved the primary end point in the intervention group compared with 16% in the control group (P=0.003). The cumulative deficit on Day 4 was lower in the intervention arm compared with the control arm: 2,507 kcal (interquartile range [IQR]=1,262 to 2,908 kcal) vs 3,844 kcal (IQR=2,620 to 4,808 kcal) (P<0.001) and 116 g (IQR=69 to 151 g) vs 191 g (IQR=147 to 244 g) protein (P<0.001), respectively. The rates of gastrointestinal complications were not significantly different between groups.Conclusions
Implementation of an EN protocol outside the ICU significantly improved the delivery of calories and protein when compared with current standard practice without increasing gastrointestinal complications. 相似文献22.
Verônica M. Couto Maria J. Prieto Daniela E. Igartúa Daniela A. Feas Lígia N.M. Ribeiro Camila M.G. Silva Simone R. Castro Viviane A. Guilherme Darlene D. Dantzger Daisy Machado Silvia del V. Alonso Eneida de Paula 《Journal of pharmaceutical sciences》2018,107(9):2411-2419
Administration of local anesthetics is one of the most effective pain control techniques for postoperative analgesia. However, anesthetic agents easily diffuse into the injection site, limiting the time of anesthesia. One approach to prolong analgesia is to entrap local anesthetic agents in nanostructured carriers (e.g., liposomes). Here, we report that using an ammonium sulphate gradient was the best strategy to improve the encapsulation (62.6%) of dibucaine (DBC) into liposomes. Light scattering and nanotracking analyses were used to characterize vesicle properties, such as, size, polydispersity, zeta potentials, and number. In vitro kinetic experiments revealed the sustained release of DBC (50% in 7 h) from the liposomes. In addition, in vitro (3T3 cells in culture) and in vivo (zebrafish) toxicity assays revealed that ionic-gradient liposomes were able to reduce DBC cyto/cardiotoxicity and morphological changes in zebrafish larvae. Moreover, the anesthesia time attained after infiltrative administration in mice was longer with encapsulated DBC (27 h) than that with free DBC (11 h), at 320 μM (0.012%), confirming it as a promising long-acting liposome formulation for parenteral drug administration of DBC. 相似文献
23.
Nandita Perumal Daniel E. Roth Johnna Perdrizet Aluísio J. D. Barros Iná S. Santos Alicia Matijasevich Diego G. Bassani 《Emerging themes in epidemiology》2018,15(1):3
Background
Postmenstrual and/or gestational age-corrected age (CA) is required to apply child growth standards to children born preterm (< 37 weeks gestational age). Yet, CA is rarely used in epidemiologic studies in low- and middle-income countries (LMICs), which may bias population estimates of childhood undernutrition. To evaluate the effect of accounting for GA in the application of growth standards, we used GA-specific standards at birth (INTERGROWTH-21st newborn size standards) in conjunction with CA for preterm-born children in the application of World Health Organization Child Growth Standards postnatally (referred to as ‘CA’ strategy) versus postnatal age for all children, to estimate mean length-for-age (LAZ) and weight-for-age (WAZ) z scores at 0, 3, 12, 24, and 48-months of age in the 2004 Pelotas (Brazil) Birth Cohort.Results
At birth (n = 4066), mean LAZ was higher and the prevalence of stunting (LAZ < ?2) was lower using CA versus postnatal age (mean ± SD): ? 0.36 ± 1.19 versus ? 0.67 ± 1.32; and 8.3 versus 11.6%, respectively. Odds ratio (OR) and population attributable risk (PAR) of stunting due to preterm birth were attenuated and changed inferences using CA versus postnatal age at birth [OR, 95% confidence interval (CI): 1.32 (95% CI 0.95, 1.82) vs 14.7 (95% CI 11.7, 18.4); PAR 3.1 vs 42.9%]; differences in inferences persisted at 3-months. At 12, 24, and 48-months, preterm birth was associated with stunting, but ORs/PARs remained attenuated using CA compared to postnatal age. Findings were similar for weight-for-age z scores.Conclusions
Population-based epidemiologic studies in LMICs in which GA is unused or unavailable may overestimate the prevalence of early childhood undernutrition and inflate the fraction of undernutrition attributable to preterm birth.24.
Stefania?Ghigo Stefano?Bande Luisella?Ciancarella Mihaela?Mircea Antonio?Piersanti Gaia?Righini José?María?Baldasano Xavier?Basaga?a Ennio?Cadum 《Air quality, atmosphere, & health》2018,11(1):69-82
A growing health concern, due to poor air quality, recently led to an increased number of studies regarding air pollution effects on public health. Consequently, close attention is paid to estimation methods of exposure to atmospheric pollutants. This paper aims to meet a specific requirement of epidemiological researchers, that is providing annual air pollution maps at municipality scale for health impact assessment purposes on national basis. Firstly, data fusion through kriging with external drift is implemented, combining pollution data from two different sources, models and measurements, in order to improve the spatial distribution of surface concentrations at grid level. Then, the assimilated data of air pollution are upscaled, so as to obtain concentrations at municipality level. This methodology was applied to Italy and Spain (in Spain, only the second step was carried out since the modeled concentration already included an assimilation procedure). In both countries, for each municipality, an estimate of the concentration value for atmospheric pollutants of major concern for human health (PM10 and NO2) was provided, offering more relevant information from a surveillance point of view. 相似文献
25.
Infrequent isolation of extensively drug-resistant (XDR) Klebsiella pneumoniae resistant to colistin in Spain 总被引:1,自引:0,他引:1
26.
27.
Juan R. Ordoñana Juan F. Sánchez Romera Lucía Colodro-Conde Eduvigis Carrillo Francisca González-Javier Juan J. Madrid-Valero José J. Morosoli-García Francisco Pérez-Riquelme José M. Martínez-Selva 《Gaceta sanitaria / S.E.S.P.A.S》2018,32(1):92-95
Genetically informative designs and, in particular, twin studies, are the most widely used methodology to analyse the relative contribution of genetic and environmental factors to inter-individual variability. These studies basically compare the degree of phenotypical similarity between monozygotic and dizygotic twin pairs. In addition to the traditional estimate of heritability, this kind of registry enables a wide variety of analyses which are unique due to the characteristics of the sample. The Murcia Twin Registry is population-based and focused on the analysis of health-related behaviour. The observed prevalence of health problems is comparable to that of other regional and national reference samples, which guarantees its representativeness. Overall, the characteristics of the Registry facilitate developing various types of research as well as genetically informative designs, and collaboration with different initiatives and consortia. 相似文献
28.
Pedro F. Sánchez-López Ignacio Ruiz-Arrondo Heiko Kotter Francisco Pacheco Martínez Manuel Segovia Hernández M. Elisa Gómez Campoy 《Gaceta sanitaria / S.E.S.P.A.S》2018,32(2):181-183
Historically, no black fly (Diptera: Simuliidae) nuisance has been reported in the Murcia Region. Back in September 2016 the Ojós City Council has contacted the Regional Public Health General Directorate for help regarding a local insect nuisance, most probably based on mosquitoes. After sampling with a BG-sentinel 2 trap, collecting adult specimens with an entomological aspirator, and collect larvae and pupae on submerged giant cane stalks at the river, it turned out that Simulium sergenti was the insect species causing the nuisance. This species is not considered particularly anthropophilic; therefore, a low vector risk for human health was considered. However, the high fly density impaired the life quality of the people at the village. A management plan was recommended, treating the river with Bacillus thuringiensis var israelensis. 相似文献
29.
Ester Teixidó-Compañó Albert Espelt Luis Sordo María J. Bravo Ana Sarasa-Renedo B. Iciar Indave Marina Bosque-Prous M. Teresa Brugal 《Gaceta sanitaria / S.E.S.P.A.S》2018,32(1):41-47