全文获取类型
收费全文 | 2446篇 |
免费 | 177篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 14篇 |
儿科学 | 146篇 |
妇产科学 | 35篇 |
基础医学 | 301篇 |
口腔科学 | 106篇 |
临床医学 | 202篇 |
内科学 | 438篇 |
皮肤病学 | 30篇 |
神经病学 | 221篇 |
特种医学 | 169篇 |
外国民族医学 | 2篇 |
外科学 | 405篇 |
综合类 | 86篇 |
预防医学 | 158篇 |
眼科学 | 21篇 |
药学 | 113篇 |
中国医学 | 4篇 |
肿瘤学 | 177篇 |
出版年
2021年 | 33篇 |
2020年 | 18篇 |
2019年 | 43篇 |
2018年 | 46篇 |
2017年 | 32篇 |
2016年 | 48篇 |
2015年 | 39篇 |
2014年 | 52篇 |
2013年 | 91篇 |
2012年 | 100篇 |
2011年 | 89篇 |
2010年 | 101篇 |
2009年 | 79篇 |
2008年 | 111篇 |
2007年 | 110篇 |
2006年 | 74篇 |
2005年 | 88篇 |
2004年 | 80篇 |
2003年 | 68篇 |
2002年 | 60篇 |
2001年 | 68篇 |
2000年 | 65篇 |
1999年 | 66篇 |
1998年 | 46篇 |
1997年 | 45篇 |
1996年 | 49篇 |
1995年 | 48篇 |
1994年 | 29篇 |
1993年 | 27篇 |
1992年 | 47篇 |
1991年 | 46篇 |
1990年 | 33篇 |
1989年 | 51篇 |
1988年 | 42篇 |
1987年 | 35篇 |
1986年 | 44篇 |
1985年 | 51篇 |
1984年 | 43篇 |
1983年 | 36篇 |
1982年 | 30篇 |
1981年 | 22篇 |
1980年 | 23篇 |
1979年 | 22篇 |
1978年 | 20篇 |
1976年 | 24篇 |
1975年 | 24篇 |
1974年 | 23篇 |
1973年 | 17篇 |
1970年 | 16篇 |
1967年 | 17篇 |
排序方式: 共有2628条查询结果,搜索用时 359 毫秒
11.
12.
This study extended aspects of Biederman's (1987) recognition-by-components (RBC) theory to the analysis of age differences in the recognition of incomplete visually-presented objects. RBC theory predicts that objects are recognizable or recoverable under conditions of fragmentation if a sufficient amount of essential structural information remains available. Objects are rendered nonrecoverable by the omission or obstruction of essential structural features at vertices and areas of concavity. Fifteen young adults and 15 older adults participated in a study of the effects of amount (25%, 45%, 65%) and type of fragmentation (recoverable, nonrecoverable) on object naming. Age-related declines in recognizing incomplete objects were associated with the amount of fragmentation, but type of fragmentation did not affect the performance of older adults. For the young adults, accuracy of performance was affected by both amount and type of fragmentation, consistent with Biederman's RBC theory. These results were interpreted as suggesting that age-related declines in perceptual closure performance have to do with non-structural factors such as the ability to inferentially augment degraded or missing visual information. 相似文献
13.
14.
15.
Evaluation of myocardial function in patients with end-stage heart failure during support with the Jarvik 2000 left ventricular assist device. 总被引:2,自引:0,他引:2
Markus Ferrari Kamuran A Kadipasaoglu Mihai Croitoru Jeff Conger Tim Myers Igor Gregoric Branislav Radovancevic George V Letsou O H Frazier 《The Journal of heart and lung transplantation》2005,24(2):226-228
In 2 patients with the Jarvik 2000 left ventricular assist device (LVAD), we assessed left ventricular systolic function through pressure-volume loops and E(max) at the beginning and end of the support period to potentially predict the possibility of pump removal without transplantation. Immediately before LVAD implantation and explantation, pressure and volume measurements were made with catheters and echocardiography, respectively, the E(max) being calculated from the slope of the pressure-volume loops, and the left ventricular ejection fraction (LVEF) being estimated by echocardiography. Transplantation was performed after 14 and 62 days, respectively, during which the LVEF increased by 75% (from 12% to 21%) in Patient 1 and remained unchanged (from 16% to 18%) in Patient 2, whereas the E(max) increased from 0.63 and 0.42 mm Hg/ml, respectively, to 1.31 and 1.07 mm Hg/ml, reflecting a 107% and 155% improvement. In these 2 cases, the E(max) was a more reliable indicator of intrinsic myocardial contractility than was the LVEF. 相似文献
16.
Zhengang Yang Xiaochen Lu Donita L. Frazier Masoud Panjehpour Mike A. Breider 《Lasers in surgery and medicine》1994,15(4):342-350
Effective antitumor photodynamic therapy (PDT) may be related to damage of vasculature within the tumor. The purpose of this study was to determine if tumor cells secrete factors that stimulate proliferation of human umbilical vein endothelial cells (HUVEC) and result in enhanced sensitivity of HUVEC to aluminum-sulfonated phthalocyanine (AISPc)-PDT. Three human tumor cell lines—pharyngeal squamous carcinoma, colonic carcinoma, and mammary carcinoma—were used in this study. Co-culture of HUVEC and either squamous carcinoma or colonic carcinoma, but not mammary carcinoma, significantly increased HUVEC proliferation and AlSPc-PDT mediated cell damage. In addition, supernatant from squamous carcinoma and colonic carcinoma cultures also stimulated HUVEC proliferation and sensitivity to AISPc-PDT. Both supernatant and cell lysate from squamous carcinoma cells contained angiogenic factors consistent with basic and acidic fibroblast growth factors, as evidenced by Western blot analysis and BALB/c 3T3 fibroblast cell proliferation assays. Collectively, these results suggest that selected tumor cell lines produce angiogenic factors that induce HUVEC proliferation and subsequently enhance sensitivity to AISPc-PDT. © 1994 Wiley-Liss, Inc. 相似文献
17.
Jamie A Koufman Catherine J Rees William D Frazier Lauren A Kilpatrick S Carter Wright Stacey L Halum Gregory N Postma 《Otolaryngology--head and neck surgery》2007,137(1):146-151
BACKGROUND: Unsedated office-based laser surgery (UOLS) of the larynx and trachea has significantly improved the treatment options for patients with laryngotracheal pathology including recurrent respiratory papillomas, granulomas, leukoplakia, and polypoid degeneration. UOLS delivered by flexible endoscopes has dramatically impacted office-based surgery by reducing the time, costs, and morbidity of surgery. OBJECTIVES: To review our experience with 443 laryngotracheal cases treated by UOLS. METHODS: The laser logbooks at the Center for Voice and Swallowing Disorders were reviewed for UOLS, and the medical and laryngological histories were detailed, as were the treatment modalities, frequencies, and complications. RESULTS: Of the 443 cases, 406 were performed with the pulsed-dye laser, 10 with the carbon-dioxide laser, and 27 with the thulium: yttrium-aluminum-garnet laser. There were no significant complications in this series. A review of indications and wavelength selection criteria is presented. CONCLUSION: Unsedated, office-based, upper aerodigestive tract laser surgery appears to be a safe and effective treatment option for many patients with laryngotracheal pathology. 相似文献
18.
19.
Nicholas J Laping Jeffrey I Everitt Kendall S Frazier Mark Burgert Melisa J Portis Caprice Cadacio Leslie I Gold Cheryl L Walker 《Clinical cancer research》2007,13(10):3087-3099
PURPOSE: Transforming growth factor beta (TGF-beta), which generally stimulates the growth of mesenchymally derived cells but inhibits the growth of epithelial cells, has been proposed as a possible target for cancer therapy. However, concerns have been raised that whereas inhibition of TGF-beta signaling could be efficacious for lesions in which TGF-beta promotes tumor development and/or progression, systemic pharmacologic blockade of this signaling pathway could also promote the growth of epithelial lesions. EXPERIMENTAL DESIGN: We examined the effect of a TGF-beta inhibitor on mesenchymal (leiomyoma) and epithelial (renal cell carcinoma) tumors in Eker rats, which are genetically predisposed to develop these tumors with a high frequency. RESULTS: Blockade of TGF-beta signaling with the ALK5/type I TGF-beta R kinase inhibitor, SB-525334, was efficacious for uterine leiomyoma; significantly decreasing tumor incidence and multiplicity, and reducing the size of these mesenchymal tumors. However, SB-525334 was also mitogenic and antiapoptotic for epithelial cells in the kidney and exacerbated the growth of epithelial lesions present in the kidneys of these animals. CONCLUSION: Although pharmacologic inhibition of TGF-beta signaling with SB-525334 may be efficacious for mesenchymal tumors, inhibition of this signaling pathway seems to promote the development of epithelial tumors. 相似文献
20.
Baldwin RT Radovancević B Duncan JM Wampler RK Frazier OH 《Texas Heart Institute journal / from the Texas Heart Institute of St. Luke's Episcopal Hospital, Texas Children's Hospital》1992,19(2):81-86
The Hemopump Cardiac Assist System is a relatively new intraarterial, axial-flow circulatory assist device that offers temporary left ventricular support to patients in refractory cardiogenic shock, without requiring major surgery for insertion. Use of the Hemopump is associated with a low complication rate. Device-related morbidity is extremely rare. Because the Hemopump is safe for use in community hospitals, the number of patients supported by this device is expected to increase. In this report, we present general guidelines for the care of patients supported by the Hemopump. We describe techniques for the management of afterload reduction, supravalvular dislodgement, device malfunction, ventricular ectopy, intracardiac shunting, and inflow cannula obstruction. 相似文献