首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   166519篇
  免费   7453篇
  国内免费   561篇
耳鼻咽喉   2682篇
儿科学   4913篇
妇产科学   3723篇
基础医学   22828篇
口腔科学   5797篇
临床医学   10777篇
内科学   40383篇
皮肤病学   5231篇
神经病学   13995篇
特种医学   3720篇
外国民族医学   2篇
外科学   19846篇
综合类   1014篇
一般理论   50篇
预防医学   16028篇
眼科学   3471篇
药学   11798篇
中国医学   909篇
肿瘤学   7366篇
  2023年   1105篇
  2022年   1959篇
  2021年   4699篇
  2020年   2368篇
  2019年   4325篇
  2018年   6050篇
  2017年   3668篇
  2016年   3575篇
  2015年   3991篇
  2014年   5288篇
  2013年   7497篇
  2012年   11766篇
  2011年   12686篇
  2010年   6683篇
  2009年   5216篇
  2008年   9718篇
  2007年   10282篇
  2006年   9481篇
  2005年   9427篇
  2004年   8467篇
  2003年   7784篇
  2002年   7226篇
  2001年   4454篇
  2000年   5017篇
  1999年   3948篇
  1998年   930篇
  1997年   735篇
  1996年   596篇
  1995年   531篇
  1994年   419篇
  1993年   340篇
  1992年   1524篇
  1991年   1266篇
  1990年   1153篇
  1989年   934篇
  1988年   816篇
  1987年   741篇
  1986年   757篇
  1985年   655篇
  1984年   465篇
  1983年   395篇
  1979年   432篇
  1975年   301篇
  1974年   386篇
  1973年   390篇
  1972年   329篇
  1971年   359篇
  1970年   324篇
  1969年   346篇
  1968年   305篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
BackgroundGastroesophageal reflux disease has a high incidence of 23%, with 29% of those with gastroesophageal reflux disease consuming nonsteroidal anti-inflammatory drugs. There are insufficient data concerning the effects of nonsteroidal anti-inflammatory drugs on the esophageal tissue. We aimed to examine the effects of well-known nonsteroidal anti-inflammatory drugs using electrophysiologic criteria on the rabbit esophageal epithelium.MethodsEsophageal epithelium mounted on Ussing chambers enabled in vitro investigation of the electrophysiological properties. Doses of 1 mg/mL, 2.5 mg/mL, 5 mg/mL ibuprofen, naproxen, and aspirin were dissolved in dimethyl sulfoxide and added to the luminal side. Esophagi were cannulated from both sides for the administration of high-dose ibuprofen in vivo, and the potential difference was monitored.ResultsIbuprofen and aspirin inhibited tissue transport functions in a dose-dependent manner. pH 4 acid and 0.1 mg/mL ibuprofen alone were not harmful; however, the combination of these agents had an additive and significance effect: 78% decrease in the potential difference and 85% decrease in the short-circuited current (Isc). The change in the potential difference in the in vivo experiments (5 mg/mL ibuprofen) was similar (52 ± 7% decrease) with in vitro experiments in the first 30 minutes.ConclusionNonsteroidal anti-inflammatory drugs were harmful to the rabbit esophageal epithelium in both the in vitro and in vivo experiments. Even though aspirin and ibuprofen affected the transport mechanisms of the esophageal epithelium, the dose-dependent decrease of tissue potential difference and Isc with ibuprofen was more pronounced than those with aspirin. The combination of harmless doses of ibuprofen and acid demonstrated that even low acidic conditions can create a disruptive environment.  相似文献   
993.
BackgroundRisk-adjusted cancer screening and prevention is a promising and continuously emerging option for improving cancer prevention. It is driven by increasing knowledge of risk factors and the ability to determine them for individual risk prediction. However, there is a knowledge gap between evidence of increased risk and evidence of the effectiveness and efficiency of clinical preventive interventions based on increased risk. This gap is, in particular, aggravated by the extensive availability of genetic risk factor diagnostics, since the question of appropriate preventive measures immediately arises when an increased risk is identified. However, collecting proof of effective preventive measures, ideally by prospective randomized preventive studies, typically requires very long periods of time, while the knowledge about an increased risk immediately creates a high demand for action.SummaryTherefore, we propose a risk-adjusted prevention concept that is based on the best current evidence making needed and appropriate preventive measures available, and which is constantly evaluated through outcome evaluation, and continuously improved based on these results. We further discuss the structural and procedural requirements as well as legal and socioeconomical aspects relevant for the implementation of this concept.  相似文献   
994.
El uso de fármacos conlleva innegables beneficios en las personas mayores, pero no está exento de efectos indeseables. La deprescripción es el proceso de revisión sistemática de la medicación con el objetivo de lograr la mejor relación riesgo-beneficio en base a la mejor evidencia disponible. Este proceso es especialmente importante en mayores polimedicados, sobretratados, frágiles, con enfermedades terminales y en el final de la vida.La deprescripción debe hacerse de forma escalonada, estableciendo un seguimiento estrecho por si aparecen problemas tras la retirada. En la toma de decisiones es muy importante contar con la opinión del paciente y de los cuidadores, valorando los objetivos del tratamiento según la situación clínica, funcional y social del enfermo.Existen múltiples herramientas para facilitar a los clínicos la tarea de seleccionar qué fármacos deprescribir (criterios Beers, STOPP-START…). Los grupos farmacológicos más susceptibles de intervención son: antihipertensivos, antidiabéticos, estatinas, benzodiacepinas, antidepresivos, anticolinérgicos, anticolinesterásicos y neurolépticos.Palabras clave: Polifarmacia, Envejecimiento, Comorbilidad, Prescripción inadecuada, Efectos adversos, Deprescripción  相似文献   
995.
Promoting a healthy diet is a relevant strategy for preventing non-communicable diseases. This study aims to evaluate the impact of an innovative tool, the SAlBi educa nutrition app, in primary healthcare dietary counseling to improve dietary profiles as well as adherence to the Mediterranean diet. A multi-center randomized control trial comprising 104 participants was performed. Both control (n = 49) and intervention (n = 55) groups attended four once-weekly sessions focusing on healthy eating habits and physical activity, over one month. As well as attending the meetings, the intervention group used the app, which provides self-monitoring and tailored dietary advice based on the Mediterranean diet model. In a second intervention (one arm trial), the potential of SAlBi educa was evaluated for three months during the COVID-19 pandemic. At 4 weeks, the intervention group had significantly increased their carbohydrate intake (7.7% (95% CI: 0.16 to 15.2)) and decreased their total fat intake (−5.7% (95% CI: −10.4 to −1.15)) compared to the control group. Significant differences were also found for carbohydrates (3.5% (95% CI: −1.0 to 5.8)), total fats (−5.9% (95% CI: −8.9 to −3.0)), fruits and vegetables (266.3 g/day (95% CI: 130.0 to 402.6)), legumes (7.7g/day (95% CI: 0.2 to 15.1)), starchy foods (36.4 g/day (95% CI: 1.1 to 71.7)), red meat (−17.5 g/day (95% CI: −34.0 to −1.1)), and processed meat (−6.6 g/day (95% CI: −13.1 to −0.1)) intakes during the COVID-19 pandemic. SAlBi educa is a useful tool to support nutrition counseling in primary healthcare, including in special situations such as the COVID-19 pandemic. Trial registration: ISRCTN57186362.  相似文献   
996.
997.
SARS-CoV-2 variant detection relies on resource-intensive whole-genome sequencing methods. We sought to develop a scalable protocol for variant detection and surveillance in Paraguay, pairing rRT-PCR for spike mutations with Nanopore sequencing. A total of 201 acute-phase nasopharyngeal samples were included. Samples were positive for the SARS-CoV-2 N2 target and tested with the Spike SNP assay to detect mutations associated with the following variants: alpha (501Y), beta/gamma (417variant/484K/501Y), delta (452R/478K), and lambda (452Q/490S). Spike SNP calls were confirmed using amplicon (Sanger) sequencing and whole-genome (Nanopore) sequencing on a subset of samples with confirmed variant lineages. Samples had a mean N2 Ct of 20.8 (SD 5.6); 198/201 samples (98.5%) tested positive in the Spike SNP assay. The most common genotype was 417variant/484K/501Y, detected in 102/198 samples (51.5%), which was consistent with the P.1 lineage (gamma variant) in Paraguay. No mutations (K417 only) were found in 64/198 (32.3%), and K417/484K was identified in 22/198 (11.1%), consistent with P.2 (zeta). Seven samples (3.5%) tested positive for 452R without 478K, and one sample with genotype K417/501Y was confirmed as B.1.1.7 (alpha). The results were confirmed using Sanger sequencing in 181/181 samples, and variant calls were consistent with Nanopore sequencing in 29/29 samples. The Spike SNP assay could improve population-level surveillance for mutations associated with SARS-CoV-2 variants and inform the judicious use of sequencing resources.  相似文献   
998.
Infertility is a growing public health problem. Consumption of antioxidant bioactive food compounds (BFCs) that include micronutrients and non-nutrients has been highlighted as a potential strategy to protect against oxidative and inflammatory damage in the male reproductive system induced by obesity, alcohol, and toxicants and, thus, improve spermatogenesis and the fertility parameters. Paternal consumption of such dietary compounds could not only benefit the fathers but their offspring as well. Studies in the new field of paternal origins of health and disease show that paternal malnutrition can alter sperm epigenome, and this can alter fetal development and program an increased risk of metabolic diseases and breast cancer in adulthood. BFCs, such as ascorbic acid, α-tocopherol, polyunsaturated fatty acids, trace elements, carnitines, N-acetylcysteine, and coenzyme Q10, have been shown to improve male gametogenesis, modulate epigenetics of germ cells, and the epigenetic signature of the offspring, restoring offspring metabolic health induced by stressors during early life. This indicates that, from a father’s perspective, preconception is a valuable window of opportunity to start potential nutritional interventions with these BFCs to maximize sperm epigenetic integrity and promote adequate fetal growth and development, thus preventing chronic disease in adulthood.  相似文献   
999.
1000.
Toxigenic Corynebacterium ulcerans is as an emerging zoonotic agent of diphtheria. We describe the zoonotic transmission of diphtheria caused by toxigenic C. ulcerans from domestic animals in Spain, confirmed by core-genome multilocus sequence typing. Alongside an increasing number of recent publications, our findings highlight the public health threat posed by diphtheria reemergence.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号