全文获取类型
收费全文 | 45231篇 |
免费 | 5032篇 |
国内免费 | 84篇 |
专业分类
耳鼻咽喉 | 323篇 |
儿科学 | 1331篇 |
妇产科学 | 899篇 |
基础医学 | 6236篇 |
口腔科学 | 1223篇 |
临床医学 | 5687篇 |
内科学 | 8908篇 |
皮肤病学 | 693篇 |
神经病学 | 3619篇 |
特种医学 | 1979篇 |
外国民族医学 | 1篇 |
外科学 | 5955篇 |
综合类 | 1164篇 |
一般理论 | 26篇 |
预防医学 | 5265篇 |
眼科学 | 848篇 |
药学 | 3772篇 |
中国医学 | 77篇 |
肿瘤学 | 2341篇 |
出版年
2021年 | 583篇 |
2020年 | 356篇 |
2019年 | 641篇 |
2018年 | 733篇 |
2017年 | 521篇 |
2016年 | 597篇 |
2015年 | 708篇 |
2014年 | 944篇 |
2013年 | 1375篇 |
2012年 | 1987篇 |
2011年 | 1994篇 |
2010年 | 1125篇 |
2009年 | 1095篇 |
2008年 | 1899篇 |
2007年 | 2007篇 |
2006年 | 1964篇 |
2005年 | 1887篇 |
2004年 | 1735篇 |
2003年 | 1653篇 |
2002年 | 1615篇 |
2001年 | 1542篇 |
2000年 | 1469篇 |
1999年 | 1465篇 |
1998年 | 610篇 |
1997年 | 481篇 |
1996年 | 503篇 |
1995年 | 498篇 |
1994年 | 438篇 |
1993年 | 491篇 |
1992年 | 1214篇 |
1991年 | 1129篇 |
1990年 | 1084篇 |
1989年 | 1059篇 |
1988年 | 991篇 |
1987年 | 989篇 |
1986年 | 986篇 |
1985年 | 912篇 |
1984年 | 778篇 |
1983年 | 643篇 |
1982年 | 444篇 |
1981年 | 358篇 |
1979年 | 590篇 |
1978年 | 486篇 |
1977年 | 378篇 |
1976年 | 398篇 |
1974年 | 432篇 |
1973年 | 400篇 |
1972年 | 386篇 |
1971年 | 349篇 |
1969年 | 358篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
971.
Zerina Lokmic Geraldine M. Mitchell Nicholas Koh Wee Chong Jacqueline Bastiaanse Yi-Wen Gerrand Yiping Zeng Elizabeth D. Williams Anthony J. Penington 《Angiogenesis》2014,17(1):1-15
Human lymphatic vascular malformations (LMs), also known as cystic hygromas or lymphangioma, consist of multiple lymphatic endothelial cell-lined lymph-containing cysts. No animal model of this disease exists. To develop a mouse xenograft model of human LM, CD34NegCD31Pos LM lymphatic endothelial cells (LM-LEC) were isolated from surgical specimens and compared to foreskin CD34NegCD31Pos lymphatic endothelial cells (LECs). Cells were implanted into a mouse tissue engineering model for 1, 2 and 4 weeks. In vitro LM-LECs showed increased proliferation and survival under starvation conditions (P < 0.0005 at 48 h, two-way ANOVA), increased migration (P < 0.001, two-way ANOVA) and formed fewer (P = 0.029, independent samples t test), shorter tubes (P = 0.029, independent samples t test) than foreskin LECs. In vivo LM-LECs implanted into a Matrigel?-containing mouse chamber model assembled to develop vessels with dilated cystic lumens lined with flat endothelium, morphology similar to that of clinical LMs. Human foreskin LECs failed to survive implantation. In LM-LEC implanted chambers the percent volume of podoplaninPos vessels was 1.18 ± 2.24 % at 1 week, 6.34 ± 2.68 % at 2 weeks and increasing to 7.67 ± 3.60 % at 4 weeks. In conclusion, the significantly increased proliferation, migration, resistance to apoptosis and decreased tubulogenesis of LM-LECs observed in vitro is likely to account for their survival and assembly into stable LM-like structures when implanted into a mouse vascularised chamber model. This in vivo xenograft model will provide the basis of future studies of LM biology and testing of potential pharmacological interventions for patients with lymphatic malformations. 相似文献
972.
973.
974.
975.
976.
977.
This paper examines factors affecting the stock price, net proceeds, and subsequent survival of biopharmaceutical firms that have gone public between 1996 and 2007 in the USA. We find that the financial condition of biopharmaceutical firms going public has deteriorated. The results also indicate that the financial condition of the firm prior to its going public and the intermediaries associated with the firm and initial public offering have little effect on first-day price increases. The findings, however, indicate that several of these financial indicators, and having prestigious underwriters, do have a significant effect on the amount of net proceeds received by the firm. 相似文献
978.
Cynthia Williams Yara Asi Amanda Raffenaud Matt Bagwell Ibrahim Zeini 《Health care management science》2016,19(4):338-346
While healthcare entities have integrated various forms of health information technology (HIT) into their systems due to claims of increased quality and decreased costs, as well as various incentives, there is little available information about which applications of HIT are actually the most beneficial and efficient. In this study, we aim to assist administrators in understanding the characteristics of top performing hospitals. We utilized data from the Health Information and Management Systems Society and the Center for Medicare and Medicaid to assess 1039 hospitals. Inputs considered were full time equivalents, hospital size, and technology inputs. Technology inputs included personal health records (PHR), electronic medical records (EMRs), computerized physician order entry systems (CPOEs), and electronic access to diagnostic results. Output variables were measures of quality, hospital readmission and mortality rate. The analysis was conducted in a two-stage methodology: Data Envelopment Analysis (DEA) and Automatic Interaction Detector Analysis (AID), decision tree regression (DTreg). Overall, we found that electronic access to diagnostic results systems was the most influential technological characteristics; however organizational characteristics were more important than technological inputs. Hospitals that had the highest levels of quality indicated no excess in the use of technology input, averaging one use of a technology component. This study indicates that prudent consideration of organizational characteristics and technology is needed before investing in innovative programs. 相似文献
979.
980.