全文获取类型
收费全文 | 1682672篇 |
免费 | 126416篇 |
国内免费 | 3751篇 |
专业分类
耳鼻咽喉 | 21710篇 |
儿科学 | 55487篇 |
妇产科学 | 46140篇 |
基础医学 | 239544篇 |
口腔科学 | 48685篇 |
临床医学 | 150226篇 |
内科学 | 330669篇 |
皮肤病学 | 38626篇 |
神经病学 | 130280篇 |
特种医学 | 63793篇 |
外国民族医学 | 242篇 |
外科学 | 256462篇 |
综合类 | 38817篇 |
现状与发展 | 4篇 |
一般理论 | 531篇 |
预防医学 | 123348篇 |
眼科学 | 40005篇 |
药学 | 123231篇 |
7篇 | |
中国医学 | 4345篇 |
肿瘤学 | 100687篇 |
出版年
2019年 | 13519篇 |
2018年 | 19949篇 |
2017年 | 15212篇 |
2016年 | 16611篇 |
2015年 | 18957篇 |
2014年 | 26212篇 |
2013年 | 37940篇 |
2012年 | 52724篇 |
2011年 | 55413篇 |
2010年 | 32766篇 |
2009年 | 30691篇 |
2008年 | 51515篇 |
2007年 | 54793篇 |
2006年 | 55252篇 |
2005年 | 52535篇 |
2004年 | 50737篇 |
2003年 | 48034篇 |
2002年 | 46239篇 |
2001年 | 91685篇 |
2000年 | 93437篇 |
1999年 | 76600篇 |
1998年 | 18774篇 |
1997年 | 16266篇 |
1996年 | 16418篇 |
1995年 | 16636篇 |
1994年 | 15228篇 |
1993年 | 14000篇 |
1992年 | 57307篇 |
1991年 | 55258篇 |
1990年 | 52945篇 |
1989年 | 50724篇 |
1988年 | 46108篇 |
1987年 | 44920篇 |
1986年 | 42194篇 |
1985年 | 39978篇 |
1984年 | 29311篇 |
1983年 | 24844篇 |
1982年 | 13842篇 |
1981年 | 12325篇 |
1979年 | 25467篇 |
1978年 | 17528篇 |
1977年 | 14849篇 |
1976年 | 13829篇 |
1975年 | 14513篇 |
1974年 | 17601篇 |
1973年 | 16907篇 |
1972年 | 15664篇 |
1971年 | 14433篇 |
1970年 | 13415篇 |
1969年 | 12504篇 |
排序方式: 共有10000条查询结果,搜索用时 20 毫秒
61.
62.
63.
64.
Kayla Ann Andrews Joel S. Owen James McCarthy David Wesche Nathalie Gobeau Thaddeus H. Grasela Jrg J. Mhrle 《CTS Clinical and Translational Science》2021,14(2):712
Volunteer infection studies using the induced blood stage malaria (IBSM) model have been shown to facilitate antimalarial drug development. Such studies have traditionally been undertaken in single‐dose cohorts, as many as necessary to obtain the dose‐response relationship. To enhance ethical and logistic aspects of such studies, and to reduce the number of cohorts needed to establish the dose‐response relationship, we undertook a retrospective in silico analysis of previously accrued data to improve study design. A pharmacokinetic (PK)/pharmacodynamic (PD) model was developed from initial fictive‐cohort data for OZ439 (mixing the data of the three single‐dose cohorts as: n = 2 on 100 mg, 2 on 200 mg, and 4 on 500 mg). A three‐compartment model described OZ439 PKs. Net growth of parasites was modeled using a Gompertz function and drug‐induced parasite death using a Hill function. Parameter estimates for the PK and PD models were comparable for the multidose single‐cohort vs. the pooled analysis of all cohorts. Simulations based on the multidose single‐cohort design described the complete data from the original IBSM study. The novel design allows for the ascertainment of the PK/PD relationship early in the study, providing a basis for rational dose selection for subsequent cohorts and studies. Study Highlights
- WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC?
- WHAT QUESTION DID THIS STUDY ADDRESS?
- WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE?
- HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE?
65.
B.R. Mussmann S.D. Mørup P.M. Skov S. Foley A.S. Brenøe F. Eldahl G.M. Jørgensen H. Precht 《Radiography》2021,27(1):1-7
IntroductionOrgan-based tube current modulation (OBTCM) is designed for anterior dose reduction in Computed Tomography (CT). The purpose was to assess dose reduction capability in chest CT using three organ dose modulation systems at different kVp settings. Furthermore, noise, diagnostic image quality and tumour detection was assessed.MethodsA Lungman phantom was scanned with and without OBTCM at 80–135/140 kVp using three CT scanners; Canon Aquillion Prime, GE Revolution CT and Siemens Somatom Flash. Thermo-luminescent dosimeters were attached to the phantom surface and all scans were repeated five times. Image noise was measured in three ROIs at the level of the carina. Three observers visually scored the images using a fivestep scale. A Wilcoxon Signed-Rank test was used for statistical analysis of differences.ResultsUsing the GE revolution CT scanner, dose reductions between 1.10 mSv (12%) and 1.56 mSv (24%) (p < 0.01) were found in the anterior segment and no differences posteriorly and laterally. Total dose reductions between 0.64 (8%) and 0.91 mSv (13%) were found across kVp levels (p < 0.00001). Maximum noise increase with OBTCM was 0.8 HU. With the Canon system, anterior dose reductions of 6–10% and total dose reduction of 0.74–0.76 mSv across kVp levels (p < 0.001) were found with a maximum noise increase of 1.1 HU. For the Siemens system, dose increased by 22–51% anteriorly; except at 100 kVp where no dose difference was found. Noise decreased by 1 to 1.5 HU.ConclusionOrgan based tube current modulation is capable of anterior and total dose reduction with minimal loss of image quality in vendors that do not increase posterior dose.Implications for practiceThis research highlights the importance of being familiar with dose reduction technologies. 相似文献
66.
The population is ageing, but while average life expectancy continues to increase, healthy life expectancy has not necessarily matched this and negative ageing stereotypes remain prevalent. Self-directed ageing stereotypes are hypothesised to play an important role in older adults’ health and well-being; however, a wide variety of terms and measures are used to explore this construct meaning there is a lack of clarity within the literature. A review was conducted to identify tools used to measure self-directed ageing stereotype in older adults and evaluate their quality. Searches identified 109 papers incorporating 40 different measures. Most common were the Philadelphia Geriatric Centre Morale Scale Attitude Towards Own Ageing (ATOA) subscale, Ageing Perceptions Questionnaire (APQ) and Attitudes to Ageing Questionnaire. Despite being most frequently used, the ATOA was developed to measure morale in older adults rather than self-directed ageing stereotypes. Over 25 terms were used to describe the concept, and it is suggested that for consistency the term “self-directed ageing stereotype” be adopted universally. Across measures, poor reporting of psychometric properties made it difficult to assess scale quality and more research is needed to fully assess measures before conclusions can be drawn as to the best tool; however, the Brief-APQ appears to hold most promise. Future research must address this issue before interventions to reduce negative self-directed ageing stereotypes can be developed and fully evaluated.Electronic supplementary materialThe online version of this article (10.1007/s10433-020-00574-7) contains supplementary material, which is available to authorized users. 相似文献
67.
68.
Syed S. Razi Joy A. Stephens-McDonnough Safi Haq Michael Fabbro Aliercy Nunez Sanchez Richard H. Epstein Nestor R. Villamizar Dao M. Nguyen 《The Journal of thoracic and cardiovascular surgery》2021,161(5):1689-1701
ObjectiveTo evaluate differences in postoperative pain control and opioids requirement in thoracic surgical patients following implementation of an Enhanced Recovery after Thoracic Surgery protocol with a comprehensive postoperative pain management strategy.Material and MethodsA retrospective analysis of a prospectively maintained database of patients undergoing pulmonary resections by robotic thoracoscopy or thoracotomy from January 1, 2017, to January 31, 2019, was conducted. Multimodal pain management strategy (opioid-sparing analgesics, infiltration of liposomal bupivacaine to intercostal spaces and surgical sites, and elimination of thoracic epidural analgesia use in thoracotomy patients) was implemented as part of Enhanced Recovery after Thoracic Surgery on February 1, 2018. Outcome metrics including patient-reported pain levels, in-hospital and postdischarge opioids use, postoperative complications, and length of stay were compared before and after protocol implementation.ResultsIn total, 310 robotic thoracoscopy and 62 thoracotomy patients met the inclusion criteria. This pain management strategy was associated with significant reduction of postoperative pain in both groups with an overall reduction of postoperative opioids requirement. Median in-hospital opioids use (morphine milligram equivalent per day) was reduced from 30 to 18.36 (P = .009) for the robotic thoracoscopy group and slightly increased from 15.48 to 21.0 (P = .27) in the thoracotomy group. More importantly, median postdischarge opioids prescribed (total morphine milligram equivalent) was significantly reduced from 480.0 to 150.0 (P < .001) and 887.5 to 150.0 (P < .001) for the thoracoscopy and thoracotomy groups, respectively. Similar short-term perioperative outcomes were observed in both groups before and following protocol implementation.ConclusionsImplementation of Enhanced Recovery after Thoracic Surgery allows safe elimination of epidural use, better pain control, and less postoperative opioids use, especially a drastic reduction of postdischarge opioid need, without adversely affecting outcomes. 相似文献
69.
70.