全文获取类型
收费全文 | 6145篇 |
免费 | 531篇 |
国内免费 | 41篇 |
学科分类
医药卫生 | 6717篇 |
出版年
2023年 | 37篇 |
2022年 | 69篇 |
2021年 | 144篇 |
2020年 | 82篇 |
2019年 | 180篇 |
2018年 | 203篇 |
2017年 | 165篇 |
2016年 | 185篇 |
2015年 | 234篇 |
2014年 | 268篇 |
2013年 | 333篇 |
2012年 | 438篇 |
2011年 | 467篇 |
2010年 | 294篇 |
2009年 | 279篇 |
2008年 | 330篇 |
2007年 | 302篇 |
2006年 | 357篇 |
2005年 | 263篇 |
2004年 | 264篇 |
2003年 | 236篇 |
2002年 | 205篇 |
2001年 | 155篇 |
2000年 | 143篇 |
1999年 | 118篇 |
1998年 | 52篇 |
1997年 | 49篇 |
1996年 | 38篇 |
1995年 | 21篇 |
1994年 | 26篇 |
1993年 | 27篇 |
1992年 | 73篇 |
1991年 | 74篇 |
1990年 | 58篇 |
1989年 | 63篇 |
1988年 | 38篇 |
1987年 | 38篇 |
1986年 | 48篇 |
1985年 | 35篇 |
1984年 | 30篇 |
1983年 | 33篇 |
1982年 | 24篇 |
1981年 | 22篇 |
1979年 | 20篇 |
1978年 | 20篇 |
1977年 | 16篇 |
1975年 | 14篇 |
1974年 | 30篇 |
1973年 | 21篇 |
1972年 | 18篇 |
排序方式: 共有6717条查询结果,搜索用时 15 毫秒
101.
Rob Mintenko David B. Kennedy Jolanta Aleksejuniene Alan G. Hannam Edwin H. Yen 《The Angle orthodontist》2020,90(2):187
Objectives:To determine changes in occlusal curves and dental tipping occurring from mandibular second premolar serial extraction, early extraction of deciduous mandibular second molars with missing second premolars, and late second premolar extraction compared with untreated controls.Materials and Methods:Information was collected from 85 subjects at three time points: T0, prior to serial extraction; T1, after serial extraction and drift prior to orthodontic treatment, and pretreatment for the late premolar extraction patients; and T2, posttreatment. Untreated age- and gender-matched controls were used for comparison. Three occlusal curves were measured on digitized mandibular casts, and dental tipping was assessed using lateral cephalograms.Results:At T0, there were no significant differences among groups. At T1, there was significant steepening of Monson''s sphere and the curve of Wilson between early and late extraction and control groups. At T2, the differences in Monson''s sphere and the curve of Wilson were fully corrected. At T1, there were significant differences in the tipping of mandibular 6''s, 4''s, and 3''s between the early extraction groups compared with the late extraction and control groups. At T2, these differences in tipping were fully corrected. There were no differences in mandibular incisor tipping between groups at T1 or T2.Conclusions:Serial extraction produced steeper occlusal curves and significant tipping of mandibular first molars, first premolars, and canines after extraction and physiologic drift (T1). Accentuated occlusal curves and tooth tipping were fully corrected following orthodontic treatment (T2). Mandibular incisor position was unchanged by serial or late second premolar extraction. 相似文献
102.
103.
104.
105.
Andreas M. Hingsammer Sarah Bixby David Zurakowski Yi-Meng Yen Young-Jo Kim 《Clinical orthopaedics and related research》2015,473(4):1224-1233
BackgroundNormal changes in acetabular version over the course of skeletal development have not been well characterized. Knowledge of normal version development is important because acetabular retroversion has been implicated in several pathologic hip processes.Questions/purposesThe purpose of this study was to characterize the orientation of the acetabulum by measuring (1) acetabular version and (2) acetabular sector angles in pediatric patients during development. We also sought to determine whether these parameters vary by sex in the developing child.MethodsWe evaluated CT images of 200 hips in 100 asymptomatic pediatric patients (45 boys, 55 girls; mean age, 13.5 years; range, 9–18 years) stratified by the status of the triradiate physis and sex. We determined the acetabular anteversion angle at various levels in the axial plane as well as acetabular sector angles at five radial planes around the acetabulum.ResultsFor both genders, anteversion angle was greater for the closed physis group throughout all levels (p < 0.001) and both open and closed physis groups were more anteverted as the cut moved caudally away from the acetabular roof (p < 0.001). At the center of the femoral head, the mean anteversion angle (± SD) in girls was 15° ± 3° in the open group and 19° ± 5° in the closed group (p < 0.001). In boys, the mean anteversion angle increased from 14° ± 4° in the open group to 19° ± 4° in the closed group (p = 0.003). In the superior, posterosuperior, and posterior planes, the acetabular sector angles were greater in the closed compared with the open physis group for both boys and girls with the largest increase occurring in the male posterosuperior plane (approximately 20°) (all p < 0.05).ConclusionsThis study demonstrates that acetabular anteversion and acetabular sector angles in both male and female subjects increase with skeletal maturity as a result of growth of the posterior wall. This suggests that radiographic appearance of acetabular retroversion may not be attributable to overgrowth of the anterior wall but rather insufficient growth of the posterior wall, which has clinical treatment implications for pincer-type impingement.
Level of Evidence
Level IV diagnostic study. 相似文献106.
107.
B Kessel K D Dahl R R Kazer C H Liu J Rivier W Vale A J Hsueh S S Yen 《The Journal of clinical endocrinology and metabolism》1988,66(2):361-366
An antagonist analog of GnRH, (Ac-delta 3-Pro1,p-F-D-Phe2,D-Trp3,6)GnRH (4F-antagonist), was administered to normal women and women with hypergonadotropic hypogonadism. Serum FSH levels were determined by both the granulosa cell aromatase bioassay and RIA. The constant infusion of 4F-antagonist (30 micrograms/kg.h) to the four hypogonadal women resulted in a more pronounced decline in bioactive FSH (62%) than in immunoreactive FSH levels (30%), and the FSH bioactive to immunoreactive ratio decreased significantly (P less than 0.05). Infusion of 4F-antagonist in normal women in the midfollicular phase revealed a similar pattern of suppression of bioactive (64%) and immunoreactive FSH (29%). When 4F-antagonist was administered sc at a dose of 80 micrograms/kg twice daily for 3 days to normal women in the midfollicular phase of their cycles, the bioactive FSH response was biphasic, with the maximal decrease on the second day, followed by return to basal levels on the third day. Correspondingly, there was a precipitous decline in serum estradiol (apparent demise of the dominant follicle), followed by a progressive rise in estradiol levels. Thus, in contrast to immunoreactive FSH levels, bioactive FSH more clearly reflects the biological action of FSH on the follicle in response to GnRH antagonist administration in women. The disparity in the quantitative decline between serum bioactive and immunoreactive FSH levels after presumed blockade of the GnRH receptor may reflect the microheterogeneity of the FSH molecule and suggests that alterations in the biological activity of secreted FSH may be GnRH dependent. 相似文献
108.
Recognition of tau epitopes by anti-neurofilament antibodies that bind to Alzheimer neurofibrillary tangles. 总被引:10,自引:10,他引:10 下载免费PDF全文
H Ksiezak-Reding D W Dickson P Davies S H Yen 《Proceedings of the National Academy of Sciences of the United States of America》1987,84(10):3410-3414
Eleven anti-neurofilament (anti-NF) monoclonal antibodies were studied for their reactivity with heat-stable, microtubule-associated proteins and Alzheimer neurofibrillary tangles (ANT). On immunoblots of NF proteins, the antibodies recognized epitopes that were variably sensitive to Escherichia coli alkaline phosphatase. Eight of the antibodies showed reactivity with ANT and decreased binding to electroblotted NF after phosphatase treatment. The same eight antibodies reacted with tau proteins from bovine and rat brain, binding to tau proteins was also substantially reduced by phosphatase. Of the eight antibodies that bound to animal tau proteins, five also bound to tau proteins from normal human brain. All of the antibodies that bound to animal tau proteins stained ANT in frozen tissue sections. Brief treatment of tissue sections with trypsin in most cases enhanced antibody binding to ANT. All antibodies that lacked reactivity with tau proteins failed to bind ANT. Phosphatase treatment of Alzheimer tissue sections did not change the immunoreactivity of ANT and neurites in senile plaques with ANT-reactive, anti-NF antibodies, except for two antibodies that showed decreased binding to ANT. In contrast, axonal staining was decreased or eliminated by phosphatase treatment, similar to the response of electroblotted NF and tau proteins. These results suggest that staining of ANT by anti-NF antibodies may be due to cross-reaction of anti-NF with epitopes in tau proteins, the epitopes in axons, NF, and tau are sensitive to the effect of phosphatase, whereas the majority of those in ANT are not, and some of the epitopes in ANT that are shared with NF and tau proteins are not readily accessible to antibody binding. 相似文献
109.
Tze Peng Lim Rick Twee-Hee Ong Pei-Yun Hon Jane Hawkey Kathryn E. Holt Tse Hsien Koh Micky Lo-Ngah Leong Jocelyn Qi-Min Teo Thean Yen Tan Mary Mah-Lee Ng Li Yang Hsu 《Antimicrobial agents and chemotherapy》2015,59(12):7899-7902
We studied polymyxin B resistance in 10 pairs of clinical Acinetobacter baumannii isolates, two of which had developed polymyxin B resistance in vivo. All polymyxin B-resistant isolates had lower growth rates than and substitution mutations in the lpx or pmrB gene compared to their parent isolates. There were significant differences in terms of antibiotic susceptibility and genetic determinants of resistance in A. baumannii isolates that had developed polymyxin B resistance in vivo compared to isolates that had developed polymyxin B resistance in vitro. 相似文献
110.
Chia-Ter Chao Szu-Ying Lee Wei-Shun Yang Huei-Wen Chen Cheng-Chung Fang Chung-Jen Yen Chih-Kang Chiang Kuan-Yu Hung Jenq-Wen Huang 《Peritoneal dialysis international》2015,35(3):333-341