全文获取类型
收费全文 | 422篇 |
免费 | 31篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 50篇 |
妇产科学 | 4篇 |
基础医学 | 54篇 |
口腔科学 | 8篇 |
临床医学 | 28篇 |
内科学 | 73篇 |
皮肤病学 | 7篇 |
神经病学 | 13篇 |
特种医学 | 58篇 |
外科学 | 33篇 |
综合类 | 81篇 |
预防医学 | 15篇 |
眼科学 | 6篇 |
药学 | 15篇 |
中国医学 | 1篇 |
肿瘤学 | 12篇 |
出版年
2021年 | 2篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 11篇 |
2014年 | 14篇 |
2013年 | 13篇 |
2012年 | 7篇 |
2011年 | 14篇 |
2010年 | 24篇 |
2009年 | 34篇 |
2008年 | 18篇 |
2007年 | 17篇 |
2006年 | 12篇 |
2005年 | 10篇 |
2004年 | 12篇 |
2003年 | 10篇 |
2002年 | 4篇 |
2001年 | 5篇 |
2000年 | 7篇 |
1999年 | 19篇 |
1998年 | 37篇 |
1997年 | 19篇 |
1996年 | 24篇 |
1995年 | 11篇 |
1994年 | 21篇 |
1993年 | 14篇 |
1992年 | 3篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 7篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有459条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
Magnetic resonance (MR) imaging, correlated with anatomic sections, was used to characterize the progressive and regressive changes in the nucleus pulposus in neonates. The spines of five fetuses and five full-term infants between 16 and 40 weeks old were studied. In anatomic sections, the nucleus pulposus was sharply demarcated from the anulus fibrosus, Sharpey fibers were conspicuous, and a plate of primitive notochord was evident in the equator of the disk. On long repetition time (TR)/long echo time (TE) or long TR/short TE MR images, Sharpey fibers (low signal intensity) and notochord (low signal intensity) could be differentiated from the high-signal-intensity nucleus pulposus and anulus fibrosus. The major differences between the fetal and infant spines were the amount of notochord in the disk and ossification in the vertebral body. 相似文献
65.
66.
Background
Dacryocystorhinostomy (DCR) is the standard surgical treatment for epiphora caused by obstructions distal to the common canaliculus. Endoscopic DCR (EDCR) and laser assisted DCR (LAEDCR) are becoming increasingly popular alternatives.Method
69 cases of EDCR were compared with 18 cases of LAEDCR. The success rates were noted at 01 week, 01, 03 and 06 months. The operating time required, incidence of adjuvant procedures, complications and post operative morbidity were recorded.Results
At the end of 06 months, 100% and 95% success was achieved with LAEDCR and EDCR respectively. Operating time, complication rates and the incidence of adjuvant procedures required were lesser in the LAEDCR group.Conclusion
In our study both the procedures have comparable success rates, though LAEDCR has an edge over EDCR in terms of decreased duration of surgery, decreased post operative morbidity and lesser complications.Key Words: Epiphora, endoscopic dacryocystorhinostomy, laser assisted endoscopic dacryocystorhinostomy 相似文献67.
68.
Background
ATP-binding cassette (ABC) transporters protect cells against unrelated (toxic) substances by pumping them across cell membranes. Earlier we showed that many ABC transporters are highly expressed in hematopoietic stem cells (HSCs) compared to more committed progenitor cells. The ABC transporter expression signature may guarantee lifelong protection of HSCs but may also preserve stem cell integrity by extrusion of agents that trigger their differentiation. Here we have studied whether non-hematopoietic stem cells (non-HSCs) exhibit a similar ABC transporter expression signature as HSCs.Results
ABC transporter expression profiles were determined in non-hematopoietic stem cells (non-HSCs) from embryonic, neonatal and adult origin as well as in various mature blood cell types. Over 11,000 individual ABC transporter expression values were generated by Taqman Low Density Arrays (TLDA) to obtain a sensitivity comparable with quantitative real-time polymerase chain reactions. We found that the vast majority of transporters are significantly higher expressed in HSCs compared to non-HSCs. Furthermore, regardless their origin, non-HSCs exhibited strikingly similar ABC transporter expression profiles that were distinct from those in HSCs. Yet, sets of transporters characteristic for different stem cell types could be identified, suggesting restricted functions in stem cell physiology. Remarkably, in HSCs we could not pinpoint any single transporter expressed at an evidently elevated level when compared to all the mature blood cell types studied.Conclusions
These findings challenge the concept that individual ABC transporters are implicated in maintaining stem cell integrity. Instead, a distinct ABC transporter expression signature may be essential for stem cell function. The high expression of specific transporters in non-HSCs and mature blood cells suggests a specialized, cell type dependent function and warrants further functional experiments to determine their exact roles in cellular (patho)physiology. 相似文献69.
E Waanders H Venselaar RHM Te Morsche DB De Koning PS Kamath VE Torres S Somlo JPH Drenth 《Clinical genetics》2010,78(1):47-56
Waanders E, Venselaar H, te Morsche RHM, de Koning DB, Kamath PS, Torres VE, Somlo S, Drenth JPH. Secondary and tertiary structure modeling reveals effects of novel mutations in polycystic liver disease genes PRKCSH and SEC63. Polycystic liver disease (PCLD) is characterized by intralobular bile duct cysts in the liver. It is caused by mutations in PRKCSH, encoding hepatocystin, and SEC63, encoding Sec63p. The main goals of this study were to screen for novel mutations and to analyze mutations for effects on protein structure and function. We screened 464 subjects including 76 probands by direct sequencing or conformation‐sensitive capillary electrophoresis. We analyzed the effects of all known and novel mutations using a combination of splice site recognition, evolutionary conservation, secondary and tertiary structure predictions, Poly Phen , and p Mut and sift . We identified a total of 26 novel mutations in PRKCSH (n = 14) and SEC63 (n = 12), including four splice site mutations, eight insertions/ deletions, six non‐sense mutations, and eight missense mutations. Out of 48 PCLD mutations, 13 were predicted to affect splicing. Most mutations were located in highly conserved regions and homology modeling for two domains of Sec63p showed severe effects of the residue substitutions. In conclusion, we identified 26 novel mutations associated with PCLD and we provide in silico analysis in order to delineate the role of these mutations. 相似文献
70.
David PS O'Brart MD FRCS FRCOphth 《Clinical & experimental optometry》2014,97(1):12-17
The aim was to review the recently published literature on excimer laser surface ablation procedures, including photorefractive keratectomy (PRK), laser sub‐epithelial keratomileusis (LASEK), microkeratome‐assisted PRK (epi‐LASIK) and trans‐epithelial (laser‐assisted) PRK, to help elucidate where and how surface ablation may best fit into current refractive surgical practice. The emphasis was on publications within the last three years and included systemic reviews, meta‐analyses and randomised controlled trials. Where such evidence did not exist, selective large series cohort studies, case‐controlled studies and case series with follow‐up preferably greater than six months were examined and included. Refractive and visual outcomes are excellent and comparable to those after LASIK even in complex cases after previous corneal surgery. Indeed, surface ablation combined with corneal collagen cross‐linking may be used in selected eyes with biomechanical instability, where LASIK is contraindicated. In addition, there is evidence to suggest that there may be less induction of higher order aberrations with surface techniques. Long‐term stability and safety appear to be extremely satisfactory. The literature supports the use of modern excimer laser surface treatments, with outcomes comparable to those after LASIK and evidence of less induction of higher‐order aberrations. Follow‐up studies at 10 to 20 years indicate excellent stability and safety. 相似文献