全文获取类型
收费全文 | 1488篇 |
免费 | 109篇 |
国内免费 | 77篇 |
专业分类
耳鼻咽喉 | 11篇 |
儿科学 | 41篇 |
妇产科学 | 29篇 |
基础医学 | 179篇 |
口腔科学 | 50篇 |
临床医学 | 220篇 |
内科学 | 350篇 |
皮肤病学 | 16篇 |
神经病学 | 88篇 |
特种医学 | 116篇 |
外科学 | 129篇 |
综合类 | 31篇 |
预防医学 | 120篇 |
眼科学 | 56篇 |
药学 | 133篇 |
中国医学 | 13篇 |
肿瘤学 | 92篇 |
出版年
2024年 | 2篇 |
2023年 | 18篇 |
2022年 | 51篇 |
2021年 | 62篇 |
2020年 | 46篇 |
2019年 | 65篇 |
2018年 | 57篇 |
2017年 | 24篇 |
2016年 | 43篇 |
2015年 | 42篇 |
2014年 | 72篇 |
2013年 | 91篇 |
2012年 | 98篇 |
2011年 | 100篇 |
2010年 | 68篇 |
2009年 | 55篇 |
2008年 | 74篇 |
2007年 | 110篇 |
2006年 | 73篇 |
2005年 | 52篇 |
2004年 | 38篇 |
2003年 | 51篇 |
2002年 | 34篇 |
2001年 | 27篇 |
2000年 | 33篇 |
1999年 | 35篇 |
1998年 | 28篇 |
1997年 | 24篇 |
1996年 | 23篇 |
1995年 | 19篇 |
1994年 | 7篇 |
1993年 | 9篇 |
1992年 | 12篇 |
1991年 | 19篇 |
1990年 | 13篇 |
1989年 | 23篇 |
1988年 | 14篇 |
1987年 | 12篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1980年 | 3篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1973年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有1674条查询结果,搜索用时 15 毫秒
21.
Nguyen Duy Hung Le Thanh Dung Dang Khanh Huyen Ngo Quang Duy Dong-Van He Nguyen Minh Duc 《International journal of medical sciences》2022,19(7):1110
Background: Prior studies have suggested a number of the subjective visual characteristics that help distinguish between spinal meningiomas and schwannomas on magnetic resonance imaging and computed tomography; however, objective quantification of the signal intensity can be useful information. This study assessed whether quantitative magnetic resonance imaging (MRI) signal intensity (SI) measurements could distinguish intradural-extramedullary schwannomas from meningiomas.Methods: From July 2019 to September 2021, 54 patients with intradural-extramedullary tumors (37 meningiomas and 17 schwannomas) underwent surgery, and tumors were verified pathologically. Defined regions of interest were used to quantify SI values on T1- (T1W) and T2-weighted images (T2W). Receiver operating characteristic curve analysis was used to obtain cutoff values and calculate the area under the curve (AUC), sensitivity (SE), specificity (SP), positive predictive value (PPV), and negative predictive value (NPV).Results: Both Maximum (T2max) and mean (T2mean) T2W SI values demonstrated outstanding (AUC: 0.91) abilities to differentiate meningiomas from schwannomas with Se, Sp, PPV, and NPV values of 94.6%, 70.6%, 87.5%, and 85.7%, respectively, for T2max and 81.1%, 88.2%, 93.8%, and 68.2% for T2mean. The maximum SI value on contrast-enhanced T1W (T1CEmax) and the T2W tumor: fat SI ratio (rTF) demonstrated acceptable abilities (AUC: 0.73 and 0.79, respectively) to differentiate meningiomas from schwannomas with Se, Sp, PPV, and NPV values of 94.6%, 70.6%, 87.5%, and 85.7%, respectively, for T1CEmax and 81.1%, 88.2%, 93.8%, and 68.2% for rTF.Conclusions: Quantitative SI values (T2max, T2mean, T2min, T1CEmax, rTF) can be used to differentiate intradural-extramedullary schwannomas from meningiomas. 相似文献
22.
23.
24.
The duties performed by radiographers, which includes transferring patients onto and off the examination table, can increase their risk of developing back and neck pain. This study used a survey to identify the assistive transfer devices Australian radiography undergraduate students are familiar with and have had practise using in the clinical setting. It also sought to determine whether students are being encouraged by other radiographers to use these devices during clinical training and if they would conform to practicing unsafe transfers if instructed to by senior staff.Results indicated that radiography students were familiar with the majority of the surveyed assistive devices such as the Patslide and X-ray cassette slider. Many of the students were unlikely to participate in unsafe work practices and were able to provide alternative methods of transferring patients. However, some of the respondents could be coerced into participating in unsafe patient transfers. Radiographers should therefore be vigilant in refraining from practicing unsafe transfer techniques as it could lead to students believing it is acceptable and emulating these practices in the work place. 相似文献
25.
Gift D. Pule Valentina J. Ngo Bitoungui Bernard Chetcha Chemegni Andre P. Kengne 《Hemoglobin》2016,40(6):377-380
High level of Hb F has been shown to improve survival in sickle cell disease. Among 453 Cameroonians with sickle cell disease, we have investigated 18 selected single-nucleotide polymorphisms (SNPs) in novel and suggestive loci associated with Hb F level identified through a genomewide association study in sickle cell disease patients in Tanzania, and whole-genome sequencing of a population from Sardinia. Seven of 10 variants reported in Sardinians were either monomorphic or very rare in the Cameroonians. No associations were observed with any SNPs and Hb F levels in Cameroonians affected by sickle cell disease. The present study illustrates the complexity of replicating Hb F-promoting variants association results across populations. 相似文献
26.
27.
Nguyen Van Vinh Chau Nguyen Thi Thu Hong Nghiem My Ngoc Tran Tan Thanh Phan Nguyen Quoc Khanh Lam Anh Nguyet Le Nguyen Truc Nhu Nguyen Thi Han Ny Dinh Nguyen Huy Man Vu Thi Ty Hang Nguyen Thanh Phong Nguyen Thi Hong Que Pham Thi Tuyen Tran Nguyen Hoang Tu Tran Tinh Hien Ngo Ngoc Quang Minh Le Manh Hung Nguyen Thanh Truong Lam Minh Yen H. Rogier van Doorn Nguyen Thanh Dung Guy Thwaites Nguyen Tri Dung Le Van Tan for the OUCRU COVID- research group 《Emerging infectious diseases》2021,27(1):310
28.
John T. Ngo Erin M. Schuman David A. Tirrell 《Proceedings of the National Academy of Sciences of the United States of America》2013,110(13):4992-4997
Newly synthesized cellular proteins can be tagged with a variety of metabolic labels that distinguish them from preexisting proteins and allow them to be identified and tracked. Many such labels are incorporated into proteins via the endogenous cellular machinery and can be used in numerous cell types and organisms. Though broad applicability has advantages, we aimed to develop a strategy to restrict protein labeling to specified mammalian cells that express a transgene. Here we report that heterologous expression of a mutant methionyl-tRNA synthetase from Escherichia coli permits incorporation of azidonorleucine (Anl) into proteins made in mammalian (HEK293) cells. Anl is incorporated site-selectively at N-terminal positions (in competition with initiator methionines) and is not found at internal sites. Site selectivity is enabled by the fact that the bacterial synthetase aminoacylates mammalian initiator tRNA, but not elongator tRNA. N-terminally labeled proteins can be selectively conjugated to a variety of useful probes; here we demonstrate use of this system in enrichment and visualization of proteins made during various stages of the cell cycle. N-terminal incorporation of Anl may also be used to engineer modified proteins for therapeutic and other applications. 相似文献
29.
J.-H. Lee M. L. Choy L. Ngo S. S. Foster Paul A. Marks 《Proceedings of the National Academy of Sciences of the United States of America》2010,107(33):14639-14644
Histone deacetylase inhibitors (HDACi) developed as anti-cancer agents have a high degree of selectivity for killing cancer cells. HDACi induce acetylation of histones and nonhistone proteins, which affect gene expression, cell cycle progression, cell migration, and cell death. The mechanism of the tumor selective action of HDACi is unclear. Here, we show that the HDACi, vorinostat (Suberoylanilide hydroxamic acid, SAHA), induces DNA double-strand breaks (DSBs) in normal (HFS) and cancer (LNCaP, A549) cells. Normal cells in contrast to cancer cells repair the DSBs despite continued culture with vorinostat. In transformed cells, phosphorylated H2AX (γH2AX), a marker of DNA DSBs, levels increased with continued culture with vorinostat, whereas in normal cells, this marker decreased with time. Vorinostat induced the accumulation of acetylated histones within 30 min, which could alter chromatin structure-exposing DNA to damage. After a 24-h culture of cells with vorinostat, and reculture without the HDACi, γH2AX was undetectable by 2 h in normal cells, while persisting in transformed cells for the duration of culture. Further, we found that vorinostat suppressed DNA DSB repair proteins, e.g., RAD50, MRE11, in cancer but not normal cells. Thus, the HDACi, vorinostat, induces DNA damage which normal but not cancer cells can repair. This DNA damage is associated with cancer cell death. These findings can explain, in part, the selectivity of vorinostat in causing cancer cell death at concentrations that cause little or no normal cell death. 相似文献
30.