全文获取类型
收费全文 | 11506篇 |
免费 | 656篇 |
国内免费 | 51篇 |
专业分类
耳鼻咽喉 | 77篇 |
儿科学 | 246篇 |
妇产科学 | 158篇 |
基础医学 | 1856篇 |
口腔科学 | 302篇 |
临床医学 | 1169篇 |
内科学 | 2297篇 |
皮肤病学 | 448篇 |
神经病学 | 1347篇 |
特种医学 | 744篇 |
外科学 | 1349篇 |
综合类 | 56篇 |
一般理论 | 4篇 |
预防医学 | 535篇 |
眼科学 | 138篇 |
药学 | 743篇 |
中国医学 | 19篇 |
肿瘤学 | 725篇 |
出版年
2023年 | 52篇 |
2022年 | 91篇 |
2021年 | 177篇 |
2020年 | 102篇 |
2019年 | 144篇 |
2018年 | 197篇 |
2017年 | 171篇 |
2016年 | 158篇 |
2015年 | 239篇 |
2014年 | 314篇 |
2013年 | 448篇 |
2012年 | 629篇 |
2011年 | 698篇 |
2010年 | 420篇 |
2009年 | 395篇 |
2008年 | 681篇 |
2007年 | 669篇 |
2006年 | 704篇 |
2005年 | 719篇 |
2004年 | 658篇 |
2003年 | 641篇 |
2002年 | 619篇 |
2001年 | 227篇 |
2000年 | 181篇 |
1999年 | 189篇 |
1998年 | 177篇 |
1997年 | 154篇 |
1996年 | 127篇 |
1995年 | 112篇 |
1994年 | 93篇 |
1993年 | 95篇 |
1992年 | 118篇 |
1991年 | 123篇 |
1990年 | 122篇 |
1989年 | 106篇 |
1988年 | 88篇 |
1987年 | 101篇 |
1986年 | 84篇 |
1985年 | 100篇 |
1984年 | 62篇 |
1983年 | 56篇 |
1982年 | 76篇 |
1981年 | 46篇 |
1980年 | 38篇 |
1979年 | 49篇 |
1978年 | 62篇 |
1975年 | 38篇 |
1974年 | 43篇 |
1973年 | 49篇 |
1972年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Ralf Wettengel Dietrich Berdel Dietrich Hofmann Jürgen Krause Claus Kroegel Rolf F. Kroidl Wolfgang Leupold Hermann Lindemann Helgo Magnussen Rolf Meister Harald Morr Dietrich Nolte Klaus F. Rabe Dietrich Reinhardt Rüdiger Sauer Gerhard Schultze-Werninghaus Dieter Ukena und Heinrich Worth 《Medizinische Klinik》1998,93(11):639-650
Ohne Zusammenfassung 相似文献
992.
993.
994.
Thomas M. Fiedler Stephan Orzada Martina Flöser Stefan H. G. Rietsch Simon Schmidt Jonathan K. Stelter Marco Wittrich Harald H. Quick Andreas K. Bitz Mark E. Ladd 《NMR in biomedicine》2022,35(5):e4656
In this study, the performance of an integrated body-imaging array for 7 T with 32 radiofrequency (RF) channels under consideration of local specific absorption rate (SAR), tissue temperature, and thermal dose limits was evaluated and the imaging performance was compared with a clinical 3 T body coil. Thirty-two transmit elements were placed in three rings between the bore liner and RF shield of the gradient coil. Slice-selective RF pulse optimizations for B1 shimming and spokes were performed for differently oriented slices in the body under consideration of realistic constraints for power and local SAR. To improve the B1+ homogeneity, safety assessments based on temperature and thermal dose were performed to possibly allow for higher input power for the pulse optimization than permissible with SAR limits. The results showed that using two spokes, the 7 T array outperformed the 3 T birdcage in all the considered regions of interest. However, a significantly higher SAR or lower duty cycle at 7 T is necessary in some cases to achieve similar B1+ homogeneity as at 3 T. The homogeneity in up to 50 cm-long coronal slices can particularly benefit from the high RF shim performance provided by the 32 RF channels. The thermal dose approach increases the allowable input power and the corresponding local SAR, in one example up to 100 W/kg, without limiting the exposure time necessary for an MR examination. In conclusion, the integrated antenna array at 7 T enables a clinical workflow for body imaging and comparable imaging performance to a conventional 3 T clinical body coil. 相似文献
995.
996.
Outbreak of carbapenem-resistant Pseudomonas aeruginosa producing SPM-1 metallo-{beta}-lactamase in a teaching hospital in southern Brazil 总被引:2,自引:0,他引:2
Zavascki AP Gaspareto PB Martins AF Gonçalves AL Barth AL 《The Journal of antimicrobial chemotherapy》2005,56(6):1148-1151
OBJECTIVES: To describe the first nosocomial outbreak of Pseudomonas aeruginosa producing SPM-1 metallo-beta-lactamase (MBL) in southern Brazil. PATIENTS AND METHODS: From January to October 2004, carbapenem-resistant P. aeruginosa (CRPA) were recovered from hospitalized patients. Mortality, site of infection/colonization, patient location and susceptibility profiles were analysed. A sample of CRPA was screened for MBL production, evaluated for the presence of bla(SPM-1), bla(IMP-1) and bla(VIM-2) genes by PCR and submitted for molecular typing by DNA macrorestriction. RESULTS: A total of 135 CRPA (one isolate per patient) were recovered. Two major antibiotic susceptibility profiles comprised 63.7% of the isolates (susceptibility to polymyxin B and aztreonam, and susceptibility only to polymyxin B). Thirty-five CRPA were screened for MBL production (10 isolates from April, June and July, and 25 from September and October) and 27 (77.1%) proved to be positive for MBL production. Twenty-one of the 24 CRPA tested carried the bla(SPM-1) gene. The mortality of patients with CRPA was 48.1% and no variable was associated with death. Molecular typing revealed the presence of a clone with four related subtypes among the bla(SPM-1)-positive CRPA. CONCLUSIONS: The prevalence of MBL production by CRPA is high and horizontal transmission is a major determinant for the spread of SPM-1 CRPA among patients in this institution. As infection control measures failed to control the spread of CRPA, continuous surveillance for MBL production is warranted. 相似文献
997.
Poppema S Kluiver JL Atayar C van den Berg A Rosenwald A Hummel M Lenze D Lammert H Stein H Joos S Barth T Dyer M Lichter P Klein U Cattoretti G Gloghini A Tu Y Stolovitzky GA Califano A Carbone A Dalla-Favera R Melzner I Bucur AJ Brüderlein S Dorsch K Hasel C Barth TF Leithäuser F Möller P 《European journal of haematology. Supplementum》2005,(66):45-52
There are several indications that classical Hodgkin lymphoma (cHL) and at least a proportion of cases of Primary Mediastinal B cell Lymphoma (PMBL) are derived from B cells at similar stages of differentiation and share common pathogenic mechanisms. The first indication was the existence of mediastinal grey zone lymphomas as identified in the 4th International Symposium on HL, with clinical, histological and immunohistochemical features intermediate between cHL and PMBL. Second, both tumor types resemble a cell that is developmentally situated in-between the germinal center reaction and a plasma cell. Third, cHL and PMBL were found to have similar gene expression profiles, including the lack of immunoglobulin expression and low levels of B cell receptor signalling molecules, and the secretion of molecules like the chemokine TARC and the prominent expression of IL-13 receptors. Fourth, both entities were found to have common genomic aberrancies, notably in 2p15 and 9p24, the sites of the REL oncogene and the tyrosine kinase gene JAK2, respectively. Further comparison of both lymphoma types may provide further insight in the pathogenic mechanisms and allow the design of diagnostic algorithms to sort out the small number of so-called mediastinal grey zone lymphomas, that appear to be intermediate between PMBL and cHL. 相似文献
998.
999.
William J. Meurer Bradley E. Barth Gary Gaddis Gary M. Vilke Samuel H.F. Lam 《The Journal of emergency medicine》2017,52(2):255-261
Background
Acute ischemic stroke (AIS) is a leading cause of morbidity and mortality. However, precisely defining the optimal treatment for individual patients early after AIS onset remains elusive. There has recently been a surge in published studies documenting the effectiveness of mechanical intra-arterial thrombectomy for treatment of a subset of patients with AIS. This therapy has been proposed and studied for the small (<1.2%) subgroup of patients with ischemic strokes who have “large vessel” strokes or strokes that fail to improve after the administration of tissue plasminogen activator (t-PA). The current rapid systematic review provides practicing emergency physicians updated information regarding mechanical thrombectomy as a treatment option for carefully selected AIS patients.Methods
A PubMed literature search was conducted from January 1996 to June 2016 and limited to human clinical trials written in English with relevant keywords. High-quality randomized controlled studies identified then underwent a structured review.Results
In total, 179 papers fulfilling the search criteria were screened and 8 appropriate articles were rigorously reviewed in detail and recommendations given on the effectiveness and indication of mechanical intra-arterial thrombectomy for the treatment of AIS.Conclusions
Mechanical intra-arterial thrombectomy reduces long-term disability in a properly selected subset of patients who have an AIS caused by large vessel occlusion. Many of these patients will have failed to improve after intravenous administration of t-PA, and mortality is not increased when combined with t-PA. Careful screening criteria should be in place to identify the limited subset of patients to whom this therapy is delivered to derive optimal treatment benefits. 相似文献1000.
Atamaniuk J Vidotto C Tschan H Bachl N Stuhlmeier KM Müller MM 《Clinical chemistry》2004,50(9):1668-1670