全文获取类型
收费全文 | 5775篇 |
免费 | 403篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 65篇 |
儿科学 | 229篇 |
妇产科学 | 256篇 |
基础医学 | 572篇 |
口腔科学 | 152篇 |
临床医学 | 445篇 |
内科学 | 1351篇 |
皮肤病学 | 213篇 |
神经病学 | 339篇 |
特种医学 | 257篇 |
外科学 | 886篇 |
综合类 | 162篇 |
预防医学 | 481篇 |
眼科学 | 93篇 |
药学 | 384篇 |
1篇 | |
中国医学 | 95篇 |
肿瘤学 | 215篇 |
出版年
2023年 | 32篇 |
2022年 | 65篇 |
2021年 | 140篇 |
2020年 | 86篇 |
2019年 | 136篇 |
2018年 | 171篇 |
2017年 | 125篇 |
2016年 | 97篇 |
2015年 | 136篇 |
2014年 | 189篇 |
2013年 | 196篇 |
2012年 | 332篇 |
2011年 | 304篇 |
2010年 | 249篇 |
2009年 | 196篇 |
2008年 | 285篇 |
2007年 | 249篇 |
2006年 | 232篇 |
2005年 | 223篇 |
2004年 | 224篇 |
2003年 | 206篇 |
2002年 | 181篇 |
2001年 | 154篇 |
2000年 | 151篇 |
1999年 | 123篇 |
1998年 | 78篇 |
1997年 | 84篇 |
1996年 | 89篇 |
1995年 | 71篇 |
1994年 | 68篇 |
1993年 | 46篇 |
1992年 | 82篇 |
1991年 | 84篇 |
1990年 | 66篇 |
1989年 | 55篇 |
1988年 | 68篇 |
1987年 | 71篇 |
1986年 | 57篇 |
1985年 | 35篇 |
1984年 | 29篇 |
1983年 | 32篇 |
1981年 | 25篇 |
1980年 | 23篇 |
1971年 | 24篇 |
1959年 | 35篇 |
1958年 | 58篇 |
1957年 | 87篇 |
1956年 | 45篇 |
1955年 | 75篇 |
1954年 | 68篇 |
排序方式: 共有6196条查询结果,搜索用时 0 毫秒
51.
52.
53.
Magaly Martinez Phuong-Vi Nguyen Maxwell Su Ftima Cardozo Adriana Valenzuela Laura Franco María Eugenia Galeano Leticia Elizabeth Rojas Chyntia Carolina Díaz Acosta Jons Fernndez Joel Ortiz Florencia del Puerto Laura Mendoza Eva Nara Alejandra Rojas Jesse J. Waggoner 《Viruses》2022,14(5)
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
54.
ngel Gimnez-Richarte Mabel Ortiz de Salazar Cristina Arbona María P. Gimnez-Richarte Miriam Collado Pedro L. Fernndez Francisco Quiles Carlos Clavijo Pascual Marco Jose-Manuel Ramos-Rincon 《Trasfusione del sangue》2022,20(4):267
BackgroundBlood transfusion centres should understand the epidemiology of emerging diseases that are transmissible through the transfusion of blood components. The risk of transmission of arboviruses through this route has become apparent in recent years. The aim of our study is to summarise the reported prevalence (viraemic rate, seroprevalence and/or antigen detection) of Chikungunya (CHIKV), Dengue (DENV) and Zika (ZIKV) viruses in blood donors according to screening test used and world region.Materials and methodsWe conducted a systematic literature review and meta-analysis having searched for information in the main bibliographic databases (MEDLINE, Embase, and Scopus). The prevalence for each of the viruses was calculated according to the screening test used and geographic location.ResultsWe included 18 records on CHIKV, 71 on DENV, and 27 on ZIKV. The highest prevalences of RNA for CHIKV were 1.9% in Puerto Rico (2014), 1.0% in Thailand (2009), and 1.0% in French Polynesia (2014–15). The highest prevalences of RNA for DENV were 5.5% in Saudi Arabia (2015–16), 2.3% in Madeira, Portugal (2012–13), and 0.6% in Brazil (2012). The highest prevalences of RNA for ZIKV were 2.8% in French Polynesia (2013–14), 2.7% in Brazil (2015–16), and 1.8% in Martinique (2016). Overall seroprevalence, as assessed by IgG antibodies, was 21.6% for CHIKV, 24.0% for DENV, and 5.1% for ZIKV.DiscussionOur study shows a high proportion of donors who are viraemic and asymptomatic, especially during outbreaks, with prevalences surpassing 5% for DENV, 1% for CHIKV, and 2% for ZIKV. These data confirm a clear threat to blood transfusion safety. The elevated seroprevalence for these three arboviruses is also indicative of their wide circulation in populations, correlating with an increased risk of infected but asymptomatic donors. Health centres and institutions must address this threat, especially in tropical regions where the biggest outbreaks occur. 相似文献
55.
Rebecca Ortiz La Banca Flvio Rebustini Willyane A. Alvarenga Emilia C. de Carvalho Mayara Lopes Kerry Milaszewski Lucila C. Nascimento 《Journal of diabetes science and technology》2022,16(3):742
Background:School-aged children often participate in type 1 diabetes (T1D) self-care tasks. Despite widespread discussion about the importance of developing self-care skills in childhood, few explain how the health care team should assess the skills of children with T1D when performing insulin injections.Objective:We sought to assess content validity evidence in two checklists regarding injection technique performed by children.Methods:Two checklists were designed based on a systematic review of the insulin injection technique. Experts in pediatric diabetes, health literacy, and diabetes education assessed the checklists regarding their clarity, objectivity, and relevance. Content validity was assessed using the content validity ratio (CVR).Results:Eleven providers (72% nurses or physicians, professional experience 19.4 ± 10.1 years, 45% of specialists in endocrinology, and 18% in pediatrics) participated in the assessment. Experts considered items containing the word homogeneity inappropriate. Items related to the needle insertion angle and the skin fold did not reach the CVR critical value. The final version of the checklist for syringe injection comprised 22 items with CVR = 0.91, and the checklist for pen injection comprised 18 items with CVR = 0.87.Conclusions:The checklists presented clear, objective, and relevant content that assesses the skills of children with T1D for insulin injection. The checklists formally present the order of the technique and all the steps for insulin injection and allow a quantitative assessment of the operational skills of children. The developed instruments offer providers the possibility of continuous assessment of the progress of the pediatric clientele until they reach independence in diabetes self-care. 相似文献
56.
奇乳海参中两个具有抗真菌活性的三萜皂苷 总被引:2,自引:0,他引:2
目的:研究奇乳海参体内的化学成分,寻找结构新颖具有抗真菌活性的三萜皂苷类成分。方法:应用多种色谱分离技术对奇乳海参体内的化学成分进行分离纯化,根据化合物的理化性质,波谱数据及化学方法鉴定其结构。结果:分离得到2个三萜皂苷化合物,分别为axilogoside A(1)和holothurin B(2),并对其抗真菌活性进行了研究(4≤MIC80≤16μg·mL^-1)。结论:化合物1为一新的三萜皂苷化舍物,化合物2为首次从奇乳海参中分离得到,它们均显示一定的抗真菌活性。 相似文献
57.
Stevanato J Bertolla RP Barradas V Spaine DM Cedenho AP Ortiz V 《Fertility and sterility》2008,90(3):889-890
We wished to verify whether semen processing by discontinuous double-layered density gradient centrifugation could improve sperm apoptotic DNA fragmentation rates using a commercially available deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling assay in 35 consecutive men presenting for assisted reproductive treatments. Although sperm motility did improve as expected, no effects were observed in sperm apoptotic DNA fragmentation rates, and this should be considered in the routine assisted reproduction setting. 相似文献
58.
Javier Agüera Ortiz M. del Mar Mas MoreyAndrés Calvo Pérez 《Progresos de Obstetricia y Ginecología》2008
Objective
To alert clinicians to the possibility of synchronous tumors in patients with gynecological cancer. An important tool in diagnosis is the family history. We describe several familial syndromes involving the development of synchronous gynecological tumors.Subjects and methods
We studied all cases of synchronous gynecological tumors in the Manacor Hospital from 1997 to 2006.Results
Synchronous gynecologic tumors represented 0.83% of all gynecological neoplasms treated in our center in the period studied.Conclusions
This kind of tumor is uncommon but should be considered by clinicians, especially in women with a familial history of cancer or in those with certain genetic syndromes. Examination aimed at excluding the presence of synchronous tumors is recommended. 相似文献59.
60.