全文获取类型
收费全文 | 24905篇 |
免费 | 1936篇 |
国内免费 | 57篇 |
专业分类
耳鼻咽喉 | 276篇 |
儿科学 | 907篇 |
妇产科学 | 576篇 |
基础医学 | 3344篇 |
口腔科学 | 693篇 |
临床医学 | 2954篇 |
内科学 | 4352篇 |
皮肤病学 | 360篇 |
神经病学 | 2253篇 |
特种医学 | 921篇 |
外国民族医学 | 1篇 |
外科学 | 3948篇 |
综合类 | 528篇 |
一般理论 | 13篇 |
预防医学 | 2385篇 |
眼科学 | 611篇 |
药学 | 1342篇 |
中国医学 | 6篇 |
肿瘤学 | 1428篇 |
出版年
2022年 | 168篇 |
2021年 | 369篇 |
2020年 | 225篇 |
2019年 | 371篇 |
2018年 | 496篇 |
2017年 | 344篇 |
2016年 | 323篇 |
2015年 | 399篇 |
2014年 | 659篇 |
2013年 | 922篇 |
2012年 | 1286篇 |
2011年 | 1347篇 |
2010年 | 791篇 |
2009年 | 681篇 |
2008年 | 1144篇 |
2007年 | 1259篇 |
2006年 | 1220篇 |
2005年 | 1280篇 |
2004年 | 1172篇 |
2003年 | 1095篇 |
2002年 | 1002篇 |
2001年 | 562篇 |
2000年 | 570篇 |
1999年 | 527篇 |
1998年 | 319篇 |
1997年 | 255篇 |
1996年 | 268篇 |
1995年 | 218篇 |
1994年 | 234篇 |
1993年 | 215篇 |
1992年 | 478篇 |
1991年 | 403篇 |
1990年 | 377篇 |
1989年 | 378篇 |
1988年 | 374篇 |
1987年 | 329篇 |
1986年 | 353篇 |
1985年 | 334篇 |
1984年 | 259篇 |
1983年 | 268篇 |
1982年 | 205篇 |
1981年 | 214篇 |
1980年 | 191篇 |
1979年 | 280篇 |
1978年 | 221篇 |
1977年 | 178篇 |
1976年 | 171篇 |
1975年 | 168篇 |
1974年 | 199篇 |
1973年 | 211篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Two methods of assessing candidates for coloured overlays were compared with the aim of determining which method had the most practical utility. A total of 58 adults were assessed as potential candidates for coloured overlays, using two methods; a questionnaire, which identified self-reported previous symptoms, and a measure of perceptual distortions immediately prior to testing. Participants were classified as normal, Meares-Irlen sensitive, and borderline sensitive. Reading speed was measured with and without coloured overlays, using the Wilkins Rate of Reading Test and the change in speed was calculated. Participants classified as normal did not show any significant benefit from reading with an overlay. In contrast, a significant reading advantage was found for the borderline and Meares-Irlen participants. Current symptom rating was found to be a significant predictor of the change in reading speed, however the previous symptom rating was not found to be a reliable predictor. These data indicate that the assessment of perceptual distortions immediately prior to measuring colour preference and reading speed is the most meaningful method of assessing pattern glare and determining the utility of coloured overlays. 相似文献
63.
64.
Tom C Nguyen Allen Cheng Frederick A Tibayan David Liang George T Daughters Neil B Ingels David Craig Miller 《European journal of cardio-thoracic surgery》2007,31(3):423-429
OBJECTIVE: Septal-lateral annular cinching ('SLAC') corrects both acute and chronic ischemic mitral regurgitation in animal experiments, which has led to the development of therapeutic surgical and interventional strategies incorporating this concept (e.g., Edwards GeoForm ring, Myocor Coapsys, Ample Medical PS3). Changes in left ventricular (LV) transmural cardiac and fiber-sheet strains after SLAC, however, remain unknown. METHODS: Eight normal sheep hearts had two triads of transmural radiopaque bead columns inserted adjacent to (anterobasal) and remote from (midlateral equatorial) the mitral annulus. Under acute, open chest conditions, 4D bead coordinates were obtained using videofluoroscopy before and after SLAC. Transmural systolic strains were calculated from bead displacements relative to local circumferential, longitudinal, and radial cardiac axes. Transmural cardiac strains were transformed into fiber-sheet coordinates (X(f), X(s), X(n)) oriented along the fiber (f), sheet (s), and sheet-normal (n) axes using fiber (alpha) and sheet (beta) angle measurements. Results: SLAC markedly reduced (approximately 60%) septal-lateral annular diameter at both end-diastole (ED) (2.5+/-0.3 to 1.0+/-0.3 cm, p=0.001) and end-systole (ES) (2.4+/-0.4 to 1.0+/-0.3 cm, p=0.001). In the LV wall remote from the mitral annulus, transmural systolic strains did not change. In the anterobasal region adjacent to the mitral annulus, ED wall thickness increased (p=0.01) and systolic wall thickening was less in the epicardial (0.28+/-0.12 vs 0.20+/-0.06, p=0.05) and midwall (0.36+/-0.24 vs 0.19+/-0.11, p=0.04) LV layers. This impaired wall thickening was due to decreased systolic sheet thickening (0.20+/-0.8 to 0.12+/-0.07, p=0.01) and sheet shear (-0.15+/-0.07 to -0.11+/-0.04, p=0.02) in the epicardium and sheet extension (0.21+/-0.11 to 0.10+/-0.04, p=0.03) in the midwall. Transmural systolic and remodeling strains in the lateral midwall (remote from the annulus) were unaffected. CONCLUSIONS: Although SLAC is an alluring concept to correct ischemic mitral regurgitation, these data suggest that extreme SLAC adversely effects systolic wall thickening adjacent to the mitral annulus by inhibiting systolic sheet thickening, sheet shear, and sheet extension. Such alterations in LV strains could result in unanticipated deleterious remodeling and warrant further investigation. 相似文献
65.
66.
67.
Paul J Meakin Maxine J Fowler Alex J Rathbone Lynne M Allen Bruce R Ransom David E Ray Angus M Brown 《Journal of cerebral blood flow and metabolism》2007,27(1):86-99
Our recent report that fructose supported the metabolism of some, but not all axons, in the adult mouse optic nerve prompted us to investigate in detail fructose metabolism in this tissue, a typical central white matter tract, as these data imply efficient fructose metabolism in the central nervous system (CNS). In artificial cerebrospinal fluid containing 10 mmol/L glucose or 20 mmol/L fructose, the stimulus-evoked compound action potential (CAP) recorded from the optic nerve consisted of three stable peaks. Replacing 10 mmol/L glucose with 10 mmol/L fructose, however, caused delayed loss of the 1st CAP peak (the 2nd and 3rd CAP peaks were unaffected). Glycogen-derived metabolic substrate(s) temporarily sustained the 1st CAP peak in 10 mmol/L fructose, as depletion of tissue glycogen by a prior period of aglycaemia or high-frequency CAP discharge rendered fructose incapable of supporting the 1st CAP peak. Enzyme assays showed the presence of both hexokinase and fructokinase (both of which can phosphorylate fructose) in the optic nerve. In contrast, only hexokinase was expressed in cerebral cortex. Hexokinase in optic nerve had low affinity and low capacity with fructose as substrate, whereas fructokinase displayed high affinity and high capacity for fructose. These findings suggest an explanation for the curious fact that the fast conducting axons comprising the 1st peak of the CAP are not supported in 10 mmol/L fructose medium; these axons probably do not express fructokinase, a requirement for efficient fructose metabolism. 相似文献
68.
Kathleen F Hunter Katherine N Moore Marion Allen 《Journal of wound, ostomy, and continence nursing》2008,35(3):334-340
PURPOSE: We undertook a feasibility study to explore the prevalence of preoperative and postoperative lower urinary tract symptoms (LUTS) in older adults undergoing elective hip arthroplasty and to determine whether a larger prospective study was warranted. METHOD: Subjects awaiting elective hip arthroplasty were recruited preoperatively from an orthopedic office and preadmission clinic at 1 university-affiliated hospital. LUTS and related quality of life were measured prehospitalization and 6 weeks postoperatively using the American Urological Association Symptom Index and quality-of-life score. Postvoid residual urine and the 24-hour pad test were used to assess bladder emptying and continence status. RESULTS: Sixteen participants (9 males, 7 females, mean age 74 years) completed the study. Preoperatively, 15 participants reported at least 1 symptom and none had discussed these with a healthcare professional. The most common LUTS were nocturia, frequency, and urgency. Postoperatively, all reported symptoms, with 8 (53%) experiencing increased symptoms with a negative impact on quality of life for 3. Recruitment was a major barrier in conducting the study and would need to be taken into account in further studies of the topic. CONCLUSION: Despite recruitment issues, we suggest larger studies of LUTS in older adults undergoing surgery are warranted to further understand potential problems and risks in transition from hospital to home. Future studies should include identification of potential reasons for increased LUTS, including urinary tract infection. 相似文献
69.
B. J. Nankivell M. D. Wavamunno R. J. Borrows M. Vitalone C. L-S Fung R. D. M. Allen J. R. Chapman P. J. O'Connell 《American journal of transplantation》2007,7(2):366-376
Mycophenolate mofetil (MMF) reduces acute rejection in controlled trials of kidney transplantation and is associated with better registry graft survival. Recent experimental studies have demonstrated additional antifibrotic properties of MMF, however, human histological data are lacking. We evaluated sequential prospective protocol kidney biopsies from two historical cohorts treated with cyclosporine (CSA)-based triple therapy including prednisolone and either MMF (n = 25) or azathioprine (AZA, n = 25). Biopsies (n = 360) were taken from euglycemic kidney-pancreas transplant recipients. Histology was independently assessed by the Banff schema and electron microscopic morphometry. MMF reduced acute rejection and OKT3 use (p < 0.05) compared with AZA. MMF therapy was associated with limited chronic interstitial fibrosis, striped fibrosis and periglomerular fibrosis (p < 0.05-0.001), mesangial matrix accumulation (p < 0.01), chronic glomerulopathy scores (p < 0.05) and glomerulosclerosis (p < 0.05). MMF was associated with delayed expression of CSA nephrotoxicity, reduced arteriolar hyalinosis, striped fibrosis and tubular microcalcification (p < 0.05-0.001). The beneficial effects of MMF remained in recipients without acute rejection. Retrospective analysis shows that MMF therapy was associated with substantially reduced fibrosis in the glomerular, microvascular and interstitial compartments, and a delayed expression of CSA nephrotoxicity. These outcomes may be due to a limitation of immune-mediated injury and suggest a direct effect of reduced fibrogenesis. 相似文献
70.