全文获取类型
收费全文 | 744000篇 |
免费 | 38684篇 |
国内免费 | 870篇 |
专业分类
耳鼻咽喉 | 9525篇 |
儿科学 | 23588篇 |
妇产科学 | 16912篇 |
基础医学 | 123380篇 |
口腔科学 | 17419篇 |
临床医学 | 65610篇 |
内科学 | 142619篇 |
皮肤病学 | 17561篇 |
神经病学 | 53310篇 |
特种医学 | 26200篇 |
外国民族医学 | 152篇 |
外科学 | 104770篇 |
综合类 | 8509篇 |
现状与发展 | 2篇 |
一般理论 | 168篇 |
预防医学 | 58286篇 |
眼科学 | 16063篇 |
药学 | 56531篇 |
1篇 | |
中国医学 | 1751篇 |
肿瘤学 | 41197篇 |
出版年
2021年 | 7133篇 |
2019年 | 7490篇 |
2018年 | 12562篇 |
2017年 | 8642篇 |
2016年 | 9366篇 |
2015年 | 10372篇 |
2014年 | 12366篇 |
2013年 | 18912篇 |
2012年 | 30311篇 |
2011年 | 32130篇 |
2010年 | 17313篇 |
2009年 | 14316篇 |
2008年 | 28426篇 |
2007年 | 30977篇 |
2006年 | 29399篇 |
2005年 | 28608篇 |
2004年 | 27435篇 |
2003年 | 25798篇 |
2002年 | 24742篇 |
2001年 | 27745篇 |
2000年 | 28308篇 |
1999年 | 23722篇 |
1998年 | 6046篇 |
1997年 | 5047篇 |
1996年 | 5051篇 |
1995年 | 4723篇 |
1992年 | 17288篇 |
1991年 | 18418篇 |
1990年 | 18441篇 |
1989年 | 17927篇 |
1988年 | 16472篇 |
1987年 | 16243篇 |
1986年 | 15102篇 |
1985年 | 14448篇 |
1984年 | 10686篇 |
1983年 | 9112篇 |
1982年 | 4798篇 |
1979年 | 10066篇 |
1978年 | 7166篇 |
1977年 | 5876篇 |
1976年 | 6090篇 |
1975年 | 7356篇 |
1974年 | 8338篇 |
1973年 | 8067篇 |
1972年 | 7456篇 |
1971年 | 7157篇 |
1970年 | 6658篇 |
1969年 | 6308篇 |
1968年 | 5901篇 |
1967年 | 5247篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Tormo Nuria Giménez Estela Martínez-Navarro María Albert Eliseo Navalpotro David Torres Ignacio Gimeno Concepción Navarro David 《European journal of clinical microbiology & infectious diseases》2022,41(4):657-662
European Journal of Clinical Microbiology & Infectious Diseases - We compared the performance of an in-house-developed flow cytometry assay for intracellular cytokine staining (FC-ICS) and a... 相似文献
92.
A. Montalto V. Piazza F. Albi R. Gherli C. Contento A. Palermo F. Musumeci 《Transplantation proceedings》2019,51(1):206-209
Background
Pump speed optimization in patients implanted with a ventricular assist device represents a major challenge during the follow-up period. We present our findings on whether combined invasive hemodynamic ramp tests and cardiopulmonary exercise testing (CPX) can help optimize patient management.Methods
Eighteen patients implanted with a HeartMate 3 (HM3) device underwent ramp tests with right heart catheterization (including central venous pressure [CVP], pulmonary artery pressure, pulmonary capillary wedge pressure [PCWP], and blood pressure) and echocardiography. Data were recorded at up to 4 speed settings. Speed changes were in steps of 200 revolutions/min (rpm). Evaluation of functional capacity by CPX was conducted according to the modified Bruce protocol.Results
Only 30% of patients had normal PCWPs at their original rpm settings. In going from lowest to highest speeds, cardiac output improved by 0.25 ± 0.35 L/min/step (total change, 1.28 ± 0.3 L/min), and PCWP decreased by 1.9 ± 0.73 mm Hg/step (total change, 6 ± 1.6 mm Hg). CVP and systolic blood pressure did not change significantly with rpm. The rpm assessment was adjusted based on test results to achieve CVPs and PCWPs as close to normal limits as possible, which was feasible in all patients. On CPX, all patients demonstrated good performance (peak VO2, 16.8 ± 3.5 mL/kg/min).Conclusion
Hemodynamic ramp testing provides an objective means of optimizing rpm, and has the potential to provide good exercise tolerance. 相似文献93.
Marta López-Fauqued Laura Campora Frédérique Delannois Mohamed El Idrissi Lidia Oostvogels Ferdinandus J. De Looze Javier Diez-Domingo Thomas C. Heineman Himal Lal Janet E. McElhaney Shelly A. McNeil Wilfred Yeo Fernanda Tavares-Da-Silva 《Vaccine》2019,37(18):2482-2493
Background
The ZOE-50 (NCT01165177) and ZOE-70 (NCT01165229) phase 3 clinical trials showed that the adjuvanted recombinant zoster vaccine (RZV) was ≥90% efficacious in preventing herpes zoster in adults. Here we present a comprehensive overview of the safety data from these studies.Methods
Adults aged ≥50 (ZOE-50) and ≥70 (ZOE-70) years were randomly vaccinated with RZV or placebo. Safety analyses were performed on the pooled total vaccinated cohort, consisting of participants receiving at least one dose of RZV or placebo. Solicited and unsolicited adverse events (AEs) were collected for 7 and 30?days after each vaccination, respectively. Serious AEs (SAEs) were collected from the first vaccination until 12?months post-last dose. Fatal AEs, vaccination-related SAEs, and potential immune-mediated diseases (pIMDs) were collected during the entire study period.Results
Safety was evaluated in 14,645 RZV and 14,660 placebo recipients. More RZV than placebo recipients reported unsolicited AEs (50.5% versus 32.0%); the difference was driven by transient injection site and solicited systemic reactions that were generally seen in the first week post-vaccination. The occurrence of overall SAEs (RZV: 10.1%; Placebo: 10.4%), fatal AEs (RZV: 4.3%; Placebo: 4.6%), and pIMDs (RZV: 1.2%; Placebo: 1.4%) was balanced between groups. The occurrence of possible exacerbations of pIMDs was rare and similar between groups. Overall, except for the expected local and systemic symptoms, the safety results were comparable between the RZV and Placebo groups irrespective of participant age, gender, or race.Conclusions
No safety concerns arose, supporting the favorable benefit-risk profile of RZV. 相似文献94.
95.
Thomas W. McDade Alexander V. Georgiev Christopher W. Kuzawa 《Evolution, Medicine, and Public Health》2016,2016(1):1-16
Immune defenses provide resistance against infectious disease that is critical to survival. But immune defenses are costly, and limited resources allocated to immunity are not available for other physiological or developmental processes. We propose a framework for explaining variation in patterns of investment in two important subsystems of anti-pathogen defense: innate (non-specific) and acquired (specific) immunity. The developmental costs of acquired immunity are high, but the costs of maintenance and activation are relatively low. Innate immunity imposes lower upfront developmental costs, but higher operating costs. Innate defenses are mobilized quickly and are effective against novel pathogens. Acquired responses are less effective against novel exposures, but more effective against secondary exposures due to immunological memory. Based on their distinct profiles of costs and effectiveness, we propose that the balance of investment in innate versus acquired immunity is variable, and that this balance is optimized in response to local ecological conditions early in development. Nutritional abundance, high pathogen exposure and low signals of extrinsic mortality risk during sensitive periods of immune development should all favor relatively higher levels of investment in acquired immunity. Undernutrition, low pathogen exposure, and high mortality risk should favor innate immune defenses. The hypothesis provides a framework for organizing prior empirical research on the impact of developmental environments on innate and acquired immunity, and suggests promising directions for future research in human ecological immunology. 相似文献
96.
97.
Talita da Silva Mendes de Farias Ariclécio Cunha de Oliveira Sandra Andreotti Fernanda Gaspar do Amaral Patrícia Chimin André Ricardo Alves de Proença Francisco Leonardo Torres Leal Rogério Antonio Laurato Sertié Amanda Baron Campana Andressa Bolsoni Lopes Arnaldo Henrique de Souza José Cipolla‐Neto Fabio Bessa Lima 《Journal of pineal research》2015,58(3):251-261
Melatonin, the main hormone produced by the pineal gland, is secreted in a circadian manner (24‐hr period), and its oscillation influences several circadian biological rhythms, such as the regulation of clock genes expression (chronobiotic effect) and the modulation of several endocrine functions in peripheral tissues. Assuming that the circadian synchronization of clock genes can play a role in the regulation of energy metabolism and it is influenced by melatonin, our study was designed to assess possible alterations as a consequence of melatonin absence on the circadian expression of clock genes in the epididymal adipose tissue of male Wistar rats and the possible metabolic repercussions to this tissue. Our data show that pinealectomy indeed has impacts on molecular events: it abolishes the daily pattern of the expression of Clock, Per2, and Cry1 clock genes and Pparγ expression, significantly increases the amplitude of daily expression of Rev‐erbα, and affects the pattern of and impairs adipokine production, leading to a decrease in leptin levels. However, regarding some metabolic aspects of adipocyte functions, such as its ability to synthesize triacylglycerols from glucose along 24 hr, was not compromised by pinealectomy, although the daily profile of the lipogenic enzymes expression (ATP‐citrate lyase, malic enzyme, fatty acid synthase, and glucose‐6‐phosphate dehydrogenase) was abolished in pinealectomized animals. 相似文献
98.
Adilson Cunha Ferreira Edward Araujo Júnior Wellington P. Martins João Francisco Jordão Antônio Hélio Oliani Simon E. Meagher 《The journal of maternal-fetal & neonatal medicine》2015,28(14):1706-1710
Objective: To assess the quality of images and video clips of fetal central nervous (CNS) structures obtained by ultrasound and transmitted via tele-ultrasound from Brazil to Australia.Methods: In this cross-sectional study, 15 normal singleton pregnant women between 20 and 26 weeks were selected. Fetal CNS structures were obtained by images and video clips. The exams were transmitted in real-time using a broadband internet and an inexpensive video streaming device. Four blinded examiners evaluated the quality of the exams using the Likert scale. We calculated the mean, standard deviation, mean difference, and p values were obtained from paired t tests.Results: The quality of the original video clips was slightly better than that observed by the transmitted video clips; mean difference considering all observers = 0.23 points. In 47/60 comparisons (78.3%; 95% CI?=?66.4–86.9%) the quality of the video clips were judged to be the same. In 182/240 still images (75.8%; 95% CI?=?70.0–80.8%) the scores of transmitted image were considered the same as the original.Conclusion: We demonstrated that long distance tele-ultrasound transmission of fetal CNS structures using an inexpensive video streaming device provided images of subjective good quality. 相似文献
99.
100.