全文获取类型
收费全文 | 526篇 |
免费 | 61篇 |
出版年
2021年 | 8篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2016年 | 10篇 |
2015年 | 11篇 |
2014年 | 16篇 |
2013年 | 13篇 |
2012年 | 19篇 |
2011年 | 20篇 |
2010年 | 11篇 |
2009年 | 16篇 |
2008年 | 25篇 |
2007年 | 28篇 |
2006年 | 16篇 |
2005年 | 20篇 |
2004年 | 18篇 |
2003年 | 26篇 |
2002年 | 23篇 |
2001年 | 12篇 |
2000年 | 20篇 |
1999年 | 18篇 |
1998年 | 9篇 |
1997年 | 9篇 |
1996年 | 5篇 |
1995年 | 9篇 |
1994年 | 13篇 |
1993年 | 8篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1990年 | 13篇 |
1989年 | 13篇 |
1988年 | 13篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 10篇 |
1984年 | 16篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 8篇 |
1978年 | 10篇 |
1977年 | 7篇 |
1976年 | 6篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1972年 | 4篇 |
1971年 | 5篇 |
1970年 | 6篇 |
1969年 | 3篇 |
排序方式: 共有587条查询结果,搜索用时 15 毫秒
541.
H Creekmore H Bellinghausen V L Young R C Wray P M Weeks P S Grasse 《Plastic and reconstructive surgery》1985,75(1):75-79
Thirty-one flexor tendon repairs in 30 patients managed by early passive motion were retrospectively compared with 31 flexor tendon repairs in 30 patients managed by 3 weeks of postoperative immobilization. Repairs were performed by several surgeons, including plastic surgical residents. There were no statistically significant differences between the two groups comparing age, zone of injury, number of tendons repaired, nature of injury, or associated injuries. No statistically significant difference was found between the two groups when total active and total passive range of motion were compared for repairs in zone I, zone II, zones III and IV, and all zones combined. In the early passive motion group in zone II, there were 12 percent excellent results, 15 percent good results, 23 percent fair results, and 50 percent poor results. In the immobilization group, there were 18 percent excellent results, 8 percent good results, 23 percent fair results, and 53 percent poor results. There was no significant difference between the two groups (p less than 0.05). 相似文献
542.
The calcareous larval skeleton of euechinoid sea urchins is synthesized by primary mesenchyme cells which ingress prior to gastrulation. In embryos of the cidaroid sea urchin Eucidaris tribuloides, no mesenchyme cells ingress before gastrulation, yet larvae later contain skeletons. This apparent paradox is resolved by immunochemical, cell lineage and morphological evidence showing that spicule-forming cells of Eucidaris are homologous to primary mesenchyme cells of euechinoids. In particular, these two cell types share expression of two cell lineage-specific gene products, are derived from the same cellular precursors, the micromeres, and undergo a similar migratory phase prior to skeletogenesis. Despite these similarities, there are far fewer spicule-forming cells in Eucidaris than in typical euechinoids and they assume a different pattern during spiculogenesis. The homology between Eucidaris spicule-forming cells and euechinoid primary mesenchyme cells indicates that a heterochrony in the time of spicule-forming cell ingression has occurred since the divergence of their respective lineages. 相似文献
543.
Previous fate mapping studies as well as the culture of isolated blastomeres have revealed that the dorsoventral axis is specified as early as the 2-cell stage in the embryos of the direct developing echinoid, Heliocidaris erythrogramma. Normally, the first cleavage plane includes the animal-vegetal axis and bisects the embryo between future dorsal and ventral halves. Experiments were performed to establish whether the dorsoventral axis is set up prior to the first cleavage division in H. erythrogramma. Eggs were elongated and fertilized in silicone tubes of a small diameter in order to orient the cleavage spindle and thus the first plane of cell division. Following first cleavage, one of the two resulting blastomeres was then microinjected with a fluorescent cell lineage tracer dye. Fate maps were made after culturing these embryos to larval stages. The results indicate that the first cleavage division can be made to occur at virtually any angle relative to the animal-vegetal and dorsoventral axes. Therefore, the dorsoventral axis is specified prior to first cleavage. We argue that this axis resides in the unfertilized oocyte rather than being set up as a consequence of fertilization. 相似文献
544.
1H NMR spectra of skinned rabbit muscle fibers show a group of relatively sharp resonance lines which presumably originate from highly mobile protein domains. Comparison with the spectrum of myosin subfragment 1 suggests that these signals may come at least partly from mobile regions of the myosin head. NMR could possibly be used to characterize the movements of crossbridges in force generation. 相似文献
545.
L A Wray 《The Western journal of medicine》1992,157(3):357-361
The rapid growth and diversity of the older population have long-term implications for health care policies in the United States. Current policies designed for a homogeneous population are increasingly obsolete. To ameliorate obstacles that handicap many ethnic minority elders and to provide equal access to adequate and acceptable health care, several factors need to be considered. Enhanced data collection and analytic techniques are needed. The effects of race or ethnicity must be separated from other biologic, environmental, socioeconomic, cultural, and temporal factors on health status and behavior. Health care professionals and organizations serving minority elders must continue to expand their advocacy efforts to articulate the findings and their concerns to policymakers. Policymakers must understand and acknowledge the implications of an increasingly diverse society and determine what will constitute adequate, accessible, and acceptable health care within continuing fiscal constrains. Program planning, implementation, and evaluation methods must be revised to meet future health care needs effectively and efficiently. 相似文献
546.
547.
Uterine contraction and physiological mechanisms of modulation 总被引:13,自引:0,他引:13
548.
A new cyanogenic glucoside, acalyphin, was isolated from the aerial parts of Acalypha indica and its structure identified mainly by 1H NMR and 相似文献
549.
550.
Wray Amy K. Olival Kevin J. Morán David Lopez Maria Renee Alvarez Danilo Navarrete-Macias Isamara Liang Eliza Simmons Nancy B. Lipkin W. Ian Daszak Peter Anthony Simon J. 《EcoHealth》2016,13(4):761-774
EcoHealth - Certain bat species serve as natural reservoirs for pathogens in several key viral families including henipa-, lyssa-, corona-, and filoviruses, which may pose serious threats to human... 相似文献