全文获取类型
收费全文 | 1149984篇 |
免费 | 121874篇 |
国内免费 | 560篇 |
专业分类
1272418篇 |
出版年
2018年 | 11004篇 |
2017年 | 10491篇 |
2016年 | 14873篇 |
2015年 | 19323篇 |
2014年 | 22972篇 |
2013年 | 33215篇 |
2012年 | 37016篇 |
2011年 | 37838篇 |
2010年 | 25932篇 |
2009年 | 24059篇 |
2008年 | 33695篇 |
2007年 | 35059篇 |
2006年 | 32726篇 |
2005年 | 31557篇 |
2004年 | 31177篇 |
2003年 | 30011篇 |
2002年 | 29164篇 |
2001年 | 51604篇 |
2000年 | 51195篇 |
1999年 | 40808篇 |
1998年 | 14573篇 |
1997年 | 15081篇 |
1996年 | 14225篇 |
1995年 | 13179篇 |
1994年 | 12691篇 |
1993年 | 12736篇 |
1992年 | 33310篇 |
1991年 | 32332篇 |
1990年 | 31420篇 |
1989年 | 30708篇 |
1988年 | 28162篇 |
1987年 | 26828篇 |
1986年 | 24979篇 |
1985年 | 24952篇 |
1984年 | 20584篇 |
1983年 | 17719篇 |
1982年 | 13408篇 |
1981年 | 12240篇 |
1980年 | 11421篇 |
1979年 | 19300篇 |
1978年 | 15141篇 |
1977年 | 13719篇 |
1976年 | 12909篇 |
1975年 | 14316篇 |
1974年 | 15446篇 |
1973年 | 15162篇 |
1972年 | 13856篇 |
1971年 | 12507篇 |
1970年 | 10932篇 |
1969年 | 10586篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
We propose a mathematical model for pendelluft flow in a single airway bifurcation. The model is motivated by an apparatus used in an experimental study of the pendelluft by Ultman et al. (1988). We derive differential equations governing the fluid flow, which directly connect physiological parameters to the variables determining the pendelluft; this approach allows us to include nonlinearity in the model. If nonlinearity is neglected, our model is identical to the R-I-C circuits used by previous investigators. If nonlinearity is retained, we show that pendelluft can occur even in perfectly symmetric airway bifurcations. For the specific apparatus used in the experiments of High et al. (1991), we demonstrate that two qualitatively different pendelluft flows can occur in the system. 相似文献
82.
83.
84.
Argon laser surgery is an effective treatment for ectasias and congenital port-wine stains; however, its use in children under the age of 13 is controversial. This paper reviews 202 children under the age of 13 who underwent argon laser treatments for congenital port-wine stains, spider angiomas, epidermal nevi, and lentigines. The clinical characteristics of port-wine stains in 170 children are discussed. Good to excellent results (moderate to complete clearing) in port-wine stains were obtained in 60 percent of patients and seemed to correlate best with lack of blanchability on pressure. Hypertrophic scarring was seen in only 7 children, all of whom had undressed wounds; no significant scarring has been seen in any subsequent child who had maintained a dressed wound postoperatively. 相似文献
85.
Reconstruction of bony structures of the face is always a problem as big as the defect and the function that must be replaced. Everything from simple grafts to sophisticated distant bone flaps has been used. Based on the studies of Cutting et al., Psillakis et al., and Casanova et al., we have developed the full-thickness galeoparietal bone flap, initially for mandibular reconstruction, but of great use for all maxillofacial reconstructions. From July of 1987 to December of 1988, 14 patients have been operated on. The experience with this flap is shown in four patients as follows: primary reconstruction of a mandible as a result of ameloblastoma, secondary reconstruction of a mandible with associated old fractures and malalignment of segments, bilateral malar reconstruction in a patient with Treacher Collins syndrome, and severe sequelae of an already treated Romberg case. Small variations could be made to best accommodate the technique used to the defect we were treating. Some technical details, the experience, the results, and possible sequelae or complications are also discussed. 相似文献
86.
Trigger finger is a relatively common clinical entity, most frequently caused by stenosing tenosynovitis. Several other conditions not related to tenosynovitis also have been described as a cause of triggering, and these have been reviewed. We present a rare anomaly of the fourth lumbrical muscle insertion as a cause of triggering of the right little finger. This was completely relieved following excision of the anomalous muscle. This rare anatomic variant should be added to the list of potential causes of trigger finger. 相似文献
87.
88.
89.
90.