全文获取类型
收费全文 | 15636篇 |
免费 | 1313篇 |
国内免费 | 34篇 |
专业分类
耳鼻咽喉 | 138篇 |
儿科学 | 700篇 |
妇产科学 | 524篇 |
基础医学 | 2040篇 |
口腔科学 | 224篇 |
临床医学 | 1907篇 |
内科学 | 2690篇 |
皮肤病学 | 262篇 |
神经病学 | 1764篇 |
特种医学 | 244篇 |
外科学 | 1525篇 |
综合类 | 118篇 |
一般理论 | 10篇 |
预防医学 | 2240篇 |
眼科学 | 203篇 |
药学 | 951篇 |
1篇 | |
中国医学 | 30篇 |
肿瘤学 | 1412篇 |
出版年
2024年 | 16篇 |
2023年 | 177篇 |
2022年 | 287篇 |
2021年 | 654篇 |
2020年 | 411篇 |
2019年 | 627篇 |
2018年 | 757篇 |
2017年 | 541篇 |
2016年 | 508篇 |
2015年 | 563篇 |
2014年 | 746篇 |
2013年 | 988篇 |
2012年 | 1399篇 |
2011年 | 1533篇 |
2010年 | 778篇 |
2009年 | 674篇 |
2008年 | 1020篇 |
2007年 | 1039篇 |
2006年 | 927篇 |
2005年 | 852篇 |
2004年 | 755篇 |
2003年 | 647篇 |
2002年 | 587篇 |
2001年 | 66篇 |
2000年 | 34篇 |
1999年 | 54篇 |
1998年 | 67篇 |
1997年 | 67篇 |
1996年 | 52篇 |
1995年 | 27篇 |
1994年 | 34篇 |
1993年 | 26篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 8篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1916年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 687 毫秒
11.
Melissa Terpstra Ivan Tkác Raghavendra Rao Rolf Gruetter 《Magnetic resonance in medicine》2006,55(5):979-983
Both ultrashort echo-time STEAM and MEGA-PRESS-edited spectroscopy were used to validate noninvasive quantification of vitamin C (ascorbate) in the developing rat brain, where changes in ascorbate concentration have been reported. Despite strong overlap with resonances from glutamine, glutamate, glutathione, and macromolecules, reliable quantification of ascorbate (Cramer-Rao lower bounds<0.2 micromol/g) by LCModel analysis of STEAM (TE=2 ms) spectra was possible at 9.4 T. Ascorbate concentrations quantified from the STEAM spectra were in very good agreement with concentrations calculated from fully resolved ascorbate resonances in MEGA-PRESS-edited spectra measured from identical volumes of interest. Ascorbate concentrations measured using STEAM decreased with increasing postnatal rat age, in agreement with published brain ascorbate concentrations measured in vitro using high-performance liquid chromatography (HPLC). 相似文献
12.
13.
Michael C. Dalsing MD Melissa Kevorkian BS Beth Raper BA Craig Nixon MS Stephen G. Lalka MD Dolores F. Cikrit MD Joseph L. Unthank PhD Malcolm B. Herring MD 《Annals of vascular surgery》1989,3(2):127-133
This study evaluates the potential for endothelial seeding of a collagen-impregnated Dacron graft with or without surface modifiers (fibronectin, heparin) to attach and retain these cells during flow. Human umbilical endothelial cells were harvested, cultured, labeled with Indium111-oxine and seeded onto 30 mm X 4 mm diameter grafts. Six graft surfaces were studied: 1) a collagen-impregnated Dacron graft, HemashieldR (C); 2) C + fibronectin (C + F); 3) C + heparin (C + H); 4) C + F + H; 5) HytrelR + F (Hyt + F); and 6) Hyt + F + H. Radioactive loss determined the percentage attachment and then percentage retention of labeled inoculum after a one-hour in vitro perfusion. Scanning electron and light microscopy demonstrated the endothelium on the graft surface following perfusion. Fibronectin-coated grafts had a significantly higher percentage attachment than those without fibronectin (ANOVA, P less than 0.05). However, the percentage retention following perfusion was similar for all Dacron grafts and statistically inferior to the HytrelR grafts studied (ANOVA, P less than 0.05). SEM evaluation of the C + F + H graft surface was qualitatively the most impressive Dacron surface for seeding, yet was inferior to the HytrelR graft. We conclude that fibronectin benefits the initial attachment of endothelium to collagen-coated Dacron rivaling the HytrelR surface. Fibronectin does not improve percentage retention of the HemashieldR surface during perfusion, therefore, some of its initial benefit is lost. 相似文献
14.
15.
John D Paulson Melissa Delgado 《JSLS, Journal of the Society of Laparoendoscopic Surgeons》2007,11(2):175-181
OBJECTIVE: This study was designed to determine the relationship between interstitial cystitis (IC), endometriosis (endo), and chronic pelvic pain (CPP) in individuals in whom nongynecological and nonurological problems had been previously ruled out. METHODS: A prospective study of 162 consecutive women with a complaint of chronic pelvic pain seen in the clinic was performed between August 2002 and December 2005. These patients underwent a workup to exclude other causes of pelvic pain, had PUF (Pain Urgency and Frequency) questionnaires filled out, and underwent a laparoscopy and a cystoscopy with hydrodistention. Pain levels were determined, and treatment was reviewed and enumerated. Results were obtained and quantified. RESULTS: In this study, 123 (76%) patients were diagnosed with active endometriosis, 133 (82%) were diagnosed with interstitial cystitis, and 107 (66%) had both disease entities simultaneously. Thirteen (8%) patients were diagnosed with pathologies unrelated to endometriosis and interstitial cystitis. Pain levels were seen to decrease at 6 months in all groups of patients with the exception of those patients with endometriosis only. CONCLUSION: CPP is a difficult, taxing, and frustrating concern for many women in the United States. These individuals have traditionally been difficult to treat. A large number of women with CPP in our patient population have been shown to have endometriosis, interstitial cystitis, or both. Therefore, a workup for premenopausal individuals with CPP involves obtaining a history that keys into possible nongynecologic causes of pain, a complete accounting of urinary problems, and a thorough history of gynecological problems. A physical examination with a comprehensive history should be performed, and the investigation may include the possibility of a simultaneous laparoscopy and cystoscopy if warranted. These procedures can serve as both a means for diagnosis and treatment of these problems when encountered. 相似文献
16.
Marilyn Hravnak Leslie A Hoffman Melissa I Saul Thomas G Zullo Julie F Cuneo Ronald V Pellegrini 《American journal of critical care》2004,13(6):499-507; discussion 508
BACKGROUND: Studies suggest that patients who undergo off-pump coronary artery bypass grafting (OPCABG) have fewer short-term complications and use fewer inpatient resources than do patients who undergo standard coronary artery bypass grafting (CABG) with extracorporeal circulation. However, dissimilarity between groups in risk factors for complications has hindered interpretation of results. OBJECTIVES: To compare the prevalence of selected complications (atrial fibrillation, stroke, reoperation, and bleeding) and inpatient resource utilization (length of stay, discharge disposition, total charges) between subjects undergoing primary isolated CABG or OPCABG who were matched with respect to key risk factors. METHODS: Retrospective, causal-comparative survey conducted in 1 center for 18 months. Patients who underwent primary isolated CABG or OPCABG were matched for sex, age (within 2 years), left ventricular ejection fraction (within 0.05), and graft-patient ratio (exact match) and compared for prevalence of new-onset atrial fibrillation, stroke, reoperation within 24 hours, and bleeding. Statistical analysis included Wilcoxon and t tests for paired comparisons. RESULTS: The sample (107 matched pairs) was 63% male, with a mean age of 66 (SD 9.5) years, a mean left ventricular ejection fraction of 0.51 (SD 0.13), and a mean graft-patient ratio of 3.41 (SD 0.74). The 2 groups did not differ significantly in New York Heart Association class (P = .43), Acute Physiology and Chronic Health Evaluation III score (P = .22), postoperative beta-blocker use (P = .73), or comorbid conditions. None of the complications examined differed significantly between pairs. CONCLUSION: Patients with comparable risk profiles have similar prevalences of selected complications after CABG and OPCABG. 相似文献
17.
18.
19.
20.
Catherine M. Cahill Melissa J. Green Rajeev Jairam Gin S. Malhi 《Early intervention in psychiatry》2007,1(2):138-149
Aim: This article reviews research centred around juvenile bipolar disorder with particular reference to diagnostic difficulties. Putative deficits are scrutinized with respect to trait likelihood and the roles of neuropsychology and neuroimaging in enhancing our understanding of juvenile bipolar disorder are discussed. Methods: Search terms including childhood, adolescent, youth and juvenile combined with the terms ‘bipolar disorder’, mania, depression and hypomania were used to identify relevant studies in MEDLINE and PsychLit. Results: Over recent years research into this relatively new disorder has increased phenomenally. Key issues within the field include diagnostic specificity, the heritability of the disorder, the impact of comorbidity and the implications of neuropsychological and neuroimaging findings. Conclusion: Despite concerning controversies in literature the diagnosis of bipolar disorder in children and adolescents as compared with adults, promising future research directions include better neurological characterization of the disorder through the application of findings from clinical populations, neuropsychological and neuroimaging research. 相似文献