全文获取类型
收费全文 | 4773篇 |
免费 | 532篇 |
出版年
2022年 | 30篇 |
2021年 | 72篇 |
2020年 | 47篇 |
2019年 | 54篇 |
2018年 | 75篇 |
2017年 | 63篇 |
2016年 | 113篇 |
2015年 | 172篇 |
2014年 | 207篇 |
2013年 | 236篇 |
2012年 | 319篇 |
2011年 | 307篇 |
2010年 | 207篇 |
2009年 | 212篇 |
2008年 | 271篇 |
2007年 | 287篇 |
2006年 | 224篇 |
2005年 | 274篇 |
2004年 | 242篇 |
2003年 | 243篇 |
2002年 | 234篇 |
2001年 | 61篇 |
2000年 | 83篇 |
1999年 | 76篇 |
1998年 | 85篇 |
1997年 | 55篇 |
1996年 | 53篇 |
1995年 | 46篇 |
1994年 | 50篇 |
1993年 | 40篇 |
1992年 | 35篇 |
1991年 | 51篇 |
1990年 | 52篇 |
1989年 | 52篇 |
1988年 | 45篇 |
1987年 | 49篇 |
1986年 | 33篇 |
1985年 | 33篇 |
1984年 | 33篇 |
1983年 | 39篇 |
1982年 | 33篇 |
1981年 | 28篇 |
1980年 | 35篇 |
1979年 | 27篇 |
1976年 | 15篇 |
1975年 | 20篇 |
1974年 | 26篇 |
1973年 | 20篇 |
1972年 | 15篇 |
1971年 | 23篇 |
排序方式: 共有5305条查询结果,搜索用时 15 毫秒
131.
132.
A new method for preparation of sections of undecalcified bone is described. Samples of ovine bone were embedded in methylmethacrylate and thick-sectioned with a cutoff machine or commercial band saw. Composite slides were prepared by gluing white acrylic to glass using cyanoacrylate glue. Bone sections were glued to the composite slide and then surface polished by grinding or ultramilling. The polished surface of the section was then etched and stained. The techniques described in this paper reduce the time spent grinding or milling sections and improve resolution of surface-stained features of undecalcified bone sections. 相似文献
133.
134.
135.
Yan-yiu Yu Chelsea Bahney Diane Hu Ralph S. Marcucio Theodore Miclau III 《Journal of visualized experiments : JoVE》2012,(62)
Assessing modes of skeletal repair is essential for developing therapies to be used clinically to treat fractures. Mechanical stability plays a large role in healing of bone injuries. In the worst-case scenario mechanical instability can lead to delayed or non-union in humans. However, motion can also stimulate the healing process. In fractures that have motion cartilage forms to stabilize the fracture bone ends, and this cartilage is gradually replaced by bone through recapitulation of the developmental process of endochondral ossification. In contrast, if a bone fracture is rigidly stabilized bone forms directly via intramembranous ossification. Clinically, both endochondral and intramembranous ossification occur simultaneously. To effectively replicate this process investigators insert a pin into the medullary canal of the fractured bone as described by Bonnarens4. This experimental method provides excellent lateral stability while allowing rotational instability to persist. However, our understanding of the mechanisms that regulate these two distinct processes can also be enhanced by experimentally isolating each of these processes. We have developed a stabilization protocol that provides rotational and lateral stabilization. In this model, intramembranous ossification is the only mode of healing that is observed, and healing parameters can be compared among different strains of genetically modified mice 5-7, after application of bioactive molecules 8,9, after altering physiological parameters of healing 10, after modifying the amount or time of stabilization 11, after distraction osteogenesis 12, after creation of a non-union 13, or after creation of a critical sized defect. Here, we illustrate how to apply the modified Ilizarov fixators for studying tibial fracture healing and distraction osteogenesis in mice. 相似文献
136.
137.
C. J. Bond 《BMJ (Clinical research ed.)》1911,1(2629):1157-1164
138.
139.
Erythrocytic cell kinetics were studied in normal dog bone marrow, at the transition between younger cells that are able to synthesize DNA, and more mature nucleated normoblasts which have lost this ability. the rate of progression out of the first group was compared to that into the second, after necessary adjustments of group sizes. No significant discrepancy was detected within the limits of resolution of autoradiographic cytokinetic analysis.
It is concluded that 'ineffective' red cell production in the normal dog, if it occurs at all, can only be very small in quantity. 相似文献
It is concluded that 'ineffective' red cell production in the normal dog, if it occurs at all, can only be very small in quantity. 相似文献
140.
Diane L. Brook 《Anthropology & education quarterly》1997,28(4):612-613
Education Reform in Democratic Spain. Oliver Boyd-Barrett and Pamela O'Malley, eds. New York: Routledge, 1995. 265 pp. 相似文献