首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   41197篇
  免费   2767篇
  国内免费   835篇
耳鼻咽喉   894篇
儿科学   661篇
妇产科学   226篇
基础医学   4479篇
口腔科学   2952篇
临床医学   2484篇
内科学   2533篇
皮肤病学   197篇
神经病学   682篇
特种医学   2438篇
外国民族医学   2篇
外科学   16709篇
综合类   4760篇
预防医学   1124篇
眼科学   543篇
药学   1626篇
  15篇
中国医学   743篇
肿瘤学   1731篇
  2024年   276篇
  2023年   498篇
  2022年   921篇
  2021年   1125篇
  2020年   1085篇
  2019年   951篇
  2018年   1160篇
  2017年   980篇
  2016年   1216篇
  2015年   1307篇
  2014年   2361篇
  2013年   2479篇
  2012年   2151篇
  2011年   2424篇
  2010年   2033篇
  2009年   2179篇
  2008年   2146篇
  2007年   2225篇
  2006年   2096篇
  2005年   2016篇
  2004年   1700篇
  2003年   1414篇
  2002年   1122篇
  2001年   997篇
  2000年   1035篇
  1999年   883篇
  1998年   713篇
  1997年   689篇
  1996年   535篇
  1995年   512篇
  1994年   448篇
  1993年   350篇
  1992年   326篇
  1991年   265篇
  1990年   235篇
  1989年   218篇
  1988年   211篇
  1987年   167篇
  1986年   190篇
  1985年   158篇
  1984年   128篇
  1983年   63篇
  1982年   117篇
  1981年   92篇
  1980年   94篇
  1979年   103篇
  1978年   77篇
  1977年   77篇
  1976年   48篇
  1973年   40篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Bone density is a key parameter in determining the surgical procedure of implant placement and for the predictability of successful implant treatment. Several clinical studies have shown lower survival rates of implants in maxilla which was attributed to poor bone quality. The present study compared the variations in the pre-operative and post-operative bone density values in Hounsfield units using CT between drilling technique and bone expansion technique at 0.25 and 1.0 mm sections at two sites which were selected in maxillary arch between the second premolar regions of either quadrants and results have shown bone expansion technique is superior to drilling technique in division III bone.  相似文献   
82.
The use of a rectangular flap is a well known technique for upper lip repair in cleft lip, but is less common for lower lip repair after tumour resection. We have found this type of flap to be favourable for lower lip reconstruction, especially for the lip to mental region. We describe herein an improvement to the technique in which two opposing rectangular flaps, with the length of one side equal to the vertical distance from the mentolabial groove to the vermilion border, were raised on the lateral sides of a U-shaped defect. Reconstruction was performed by interdigitation of the two flaps and a bilateral vermilion advancement flap. This new approach allows a distinct mentolabial groove and mental protuberance to be created by utilizing two opposing rectangular flaps and redundant tissue, without sacrificing sensation and muscle function. Our results suggest that the technique provides excellent functional and cosmetic outcomes in restoration of the lower lip in properly selected patients.  相似文献   
83.

Objective

The objective of this paper is to show that platysma flaps have good results and should be an alternative in reconstructive surgery for oral tumors when microsurgery is not possible. It is a versatile, portable, and thin flap, is easy to perform, and can be obtained during neck dissection, with a primary closure of the donor site.

Methods

Five cases are presented, three men and two women, 51 and 71 years old, with medium size (2–4 cm) defects of oral cavity after the excision of squamous cell carcinomas. All of them were reconstructed with a platysma flap after neck dissection. This reconstruction technique was chosen because of the poor conditions of these patients to allow a microsurgical reconstruction.

Results

Non-local complications occurred with this technique. Overall aesthetic results were acceptable in all the patients. There were no cases of total necrosis flap, dehiscence, fistula or fibrosis. Only one case of partial necrosis occurred in one end of the flap, which was resolved with excision of necrotic tissue and closure by secondary intention.

Conclusion

The platysma flap is a good method to reconstruct small and medium sized defects of oral cavity, especially in patients where a microsurgery reconstruction is not possible.  相似文献   
84.
<正>口底缺损修复的目的主要是保持舌的活动度,以恢复其语言和吞咽功能。由于口底解剖结构的特殊性,口底缺损很难通过直接拉拢缝合来关闭伤口。植皮修复也会由于后期的瘢痕挛缩而影响舌的功能运动,舌瓣修复会大大影响舌的活动度,胸大肌皮瓣或背阔肌皮瓣的体积过大,现在已很少被采用。因此,要根据口底缺损大小和病人全身情况来选择合适的游离、带蒂或局部组织瓣移植修复。本文就近年来这方面的研究进展作一综述。  相似文献   
85.
Orbital manifestations occur in less than 1% of patients with neurofibromatosis type 1 (NF1). These manifestations are frequently associated with sphenoid wing dysplasia. The typical radiologic feature is partial or total loss of the greater wing of the sphenoid bone, which leads to herniation of the temporal lobe through the orbital cavity resulting in proptosis and pulsating exophthalmos. Traditional reconstruction of this bone defect involves split bone grafting or titanium mesh. However, these techniques have some limitations due to bone resorption and infection risk. We report the use of 0.85 mm titanium-reinforced porous polyethylene implant sheet in three cases of orbital neurofibromatosis with sphenoid dysplasia. The role of this material was to create a barrier between the brain and orbital cavity. The implant sheet was modeled intraoperatively to reconstruct the orbital cavity anatomy and fitted without any screws. The malleability of the implant allows quick reconstruction of the curved orbital skeleton. Furthermore, the implant doesn't interfere with postoperative imaging and may decrease risk infection.  相似文献   
86.
目的:探讨经济有效的治疗放射性颌骨坏死(RONJ)的手术方式。方法77例RONJ根据颌骨坏死的范围、软组织条件选择不同治疗方式。方案1:骨坏死范围局限,牙龈及周围软组织无明显炎症的采用局部刮治或方块切除术;方案2:骨坏死范围较大、周围软组织炎症明显和(或)伴有明显纤维化的病例在控制炎症后,扩大切除同时行血管化游离复合组织瓣修复。结果21例采用方案1,其中15例一期愈合、6例行二次刮治或方块切除;56例采用方案2,其中软组织条件较好的30例,22例一期愈合,5例延期愈合,3例发生骨组织瓣血管危象,经探查和再吻合后1例正常愈合,2例仍发生组织瓣坏死;软组织炎症明显或伴有局部组织明显纤维化26例中,7例出现骨组织瓣血管危象,探查和再吻合后5例正常,2例出现骨坏死,9例一期愈合,15例局部出现不同程度软组织感染坏死,延期愈合。结论局限性放射性颌骨坏死可采用刮治或方块切除;骨坏死范围较大、软组织条件较好的采用血管化游离组织瓣进行修复;软组织纤维化明显的失败率较高,临床使用时应综合多方因素考虑。  相似文献   
87.
Background: Vascular calcification significantly increases the rates of cardiovascular mortality in hemodialysis (HD) patients. Abnormalities in mineral metabolism may play a role in the pathogenesis of arterial calcification. Whether patients treated with non-calcium-based phosphate binders had reduced aortic vascular calcification compared to those treated with calcium-based phosphate binders is still unclear. Methods: We searched multiple databases for studies published through August 2013 that evaluated the effects of non-calcium-based phosphate binders (NCBP) versus calcium-based phosphate binders (CBP) on cardiovascular calcification and bone remodeling among dialysis patients. We summarized test performance characteristics with the use of forest plots, fixed and random effects models, and Egger regression test. Results: Eighteen eligible randomized controlled trials totaling 3676 patients were included. Meta-analysis results showed NCBP could significantly attenuate the progression of coronary artery calcification than CBP (WMD: ?144.62, 95% CI: ?285.62 to ?3.63). The serum calcium levels significant lower in NCPB group than in CPB groups (WMD: ?0.26, 95% CI: ?0.37 to ?0.14), but the serum iPTH levels were significantly higher in NCPB groups (WMD: 57.1, 95% CI: 13.42 to 100.78). The osteoid volume and osteoblast numbers were significant higher in NCPB group than in CPB group (WMD: 1.75, 95% CI: 0.78 to 2.73 for osteoid volume; WMD: 4.49, 95% CI: 1.83 to 7.15 for osteoblast numbers). The Egger regression test also showed no potential publication bias (p?=?0.725). Conclusions: Based on available data, NCBPs have equally effective with CBPs for serum phosphate control. But there was significantly lower incidence of coronary artery calcification and a significant higher bone formatting rate in NCBP groups than in CBP groups. So we recommend NCBPs as phosphate binders for HD patients.  相似文献   
88.
正Lower body weight or body mass index(BMI)has been known to be higher risk of developing osteoporosis and low-energy fractures via mechanical loading and other factors in both men and women[1].Recently,there have been new insights into the relationships between body composition and bone health.However,most of the previous studies regarding the relative effect of body composition on bone mass yielded inconsistent  相似文献   
89.
临床上对于骨缺损的治疗从截肢,自体骨、异体骨移植,到目前的生物活性材料、骨组织工程、基因工程治疗,依然没有能够彻底进行骨缺损修复的方法,这也一直是医学界关注和研究的热点。究其原因一方面是因为各种方法的技术水平还不完善如手术时间和方法掌握,生物活性材料的制作等,另一方面是因为骨缺损的局部反应较复杂如骨髓损伤较重,血运较差,断端存在的硬化反应等以及传统治疗后的并发症较多如免疫排斥较重,成骨作用不良,骨折不愈合,神经损伤长期引发的疼痛等,这些原因都在不同程度的制约骨缺损研究的前进。只有从骨的修复与生长机制出发,联合应用多种方法,相互补其不足,从中找到突破点,才能完善骨缺损修复,缩短治疗时间,提高病人的生活质量。本文简要描述自体和异体骨移植在治疗骨缺损时的优缺点,着重叙述骨组织工程与基因工程近年来的研究热点,包括生物材料的更新换代、目的细胞的种类增加、生长因子与基因载体的研究进展等,这其中探讨了生物修复骨缺损工程中两种方法各自的利弊,阐述两种工程联合应用的优缺互补,最后提出骨缺损治疗研究方向上的新思路与新问题。  相似文献   
90.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号