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   208047篇
  免费   3981篇
  国内免费   1783篇
耳鼻咽喉   1681篇
儿科学   7093篇
妇产科学   3798篇
基础医学   20349篇
口腔科学   2089篇
临床医学   16179篇
内科学   36302篇
皮肤病学   1453篇
神经病学   18147篇
特种医学   10028篇
外国民族医学   17篇
外科学   32110篇
综合类   6509篇
现状与发展   4篇
一般理论   7篇
预防医学   20164篇
眼科学   3489篇
药学   12861篇
  21篇
中国医学   2260篇
肿瘤学   19250篇
  2023年   422篇
  2022年   555篇
  2021年   1318篇
  2020年   1105篇
  2019年   1170篇
  2018年   23064篇
  2017年   18333篇
  2016年   20449篇
  2015年   2410篇
  2014年   2647篇
  2013年   2601篇
  2012年   9497篇
  2011年   23612篇
  2010年   20466篇
  2009年   12751篇
  2008年   21253篇
  2007年   23373篇
  2006年   2308篇
  2005年   3895篇
  2004年   4612篇
  2003年   5521篇
  2002年   3498篇
  2001年   1149篇
  2000年   1215篇
  1999年   894篇
  1998年   631篇
  1997年   594篇
  1996年   412篇
  1995年   401篇
  1994年   366篇
  1993年   252篇
  1992年   361篇
  1991年   365篇
  1990年   338篇
  1989年   244篇
  1988年   242篇
  1987年   188篇
  1986年   144篇
  1985年   145篇
  1984年   102篇
  1983年   64篇
  1982年   49篇
  1981年   34篇
  1980年   60篇
  1979年   34篇
  1974年   33篇
  1970年   36篇
  1938年   63篇
  1932年   57篇
  1930年   46篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.

Background

Given the lack of established indications for elective nodal irradiation (ENI) in ypN0 patients after neoadjuvant chemotherapy (NAC) and breast-conserving surgery (BCS), we set out to investigate the role of ENI in ypN0 patients according to subtype and pathologic complete remission (pCR) status.

Patients and Methods

We analyzed 261 patients who received NAC followed by BCS and adjuvant radiotherapy in 13 institutions of the Korean Radiation Oncology Group from 2005 to 2011. The tumors were classified into one of 3 subtypes: luminal (estrogen receptor positive or progesterone receptor positive and HER2 negative), HER2 (HER2 positive), or triple negative (estrogen receptor, progesterone receptor, and HER2 negative). We compared locoregional control (LRC), disease-free survival (DFS), and overall survival (OS) according to ENI in different subgroups generated by the subtype and pCR statuses.

Results

In all patients, the 5-year LRC, DFS, and OS rates were 96.0%, 91.0%, and 96.8%, respectively. In all patients, axillary lymph node dissection was found to be the only favorable factor for LRC (P = .023) and DFS (P = .001). Age ≥ 50 years (P = .027), negative resection margin (P = .002), and axillary lymph node dissection (P = .002) were all favorable factors for OS. ENI did not affect LRC, DFS, or OS. Subgroup analysis by tumor subtype and pCR showed that ENI was not associated with greater LRC or DFS in any subgroups.

Conclusion

In ypN0 patients after NAC and BCS, ENI did not improve LRC or survival, regardless of subtype or primary tumor response. This result should be verified through larger prospective trials.  相似文献   
22.
23.
24.
A pathological feature in atherosclerosis is the dysfunction and death of vascular endothelial cells (EC). Oxidized low‐density lipoprotein (LDL), known to accumulate in the atherosclerotic arterial walls, impairs endothelium‐dependent relaxation and causes EC apoptosis. A major bioactive ingredient of the oxidized LDL is lysophosphatidylcholine (LPC), which at higher concentrations causes apoptosis and necrosis in various EC. There is hitherto no report on LPC‐induced cytotoxicity in brain EC. In this work, we found that LPC caused cytosolic Ca2+ overload, mitochondrial membrane potential decrease, p38 activation, caspase 3 activation and eventually apoptotic death in mouse cerebral bEND.3 EC. In contrast to reported reactive oxygen species (ROS) generation by LPC in other EC, LPC did not trigger ROS formation in bEND.3 cells. Pharmacological inhibition of p38 alleviated LPC‐inflicted cell death. We examined whether heparin could be cytoprotective: although it could not suppress LPC‐triggered Ca2+ signal, p38 activation and mitochondrial membrane potential drop, it did suppress LPC‐induced caspase 3 activation and alleviate LPC‐inflicted cytotoxicity. Our data suggest LPC apoptotic death mechanisms in bEND.3 might involve mitochondrial membrane potential decrease and p38 activation. Heparin is protective against LPC cytotoxicity and might intervene steps between mitochondrial membrane potential drop/p38 activation and caspase 3 activation.  相似文献   
25.
目的 探讨巩膜外黄斑外垫压术治疗硅油填充术后复发性超高度近视黄斑裂孔性视网膜脱离(macular hole retinal detachment,MHRD) 的可行性及疗效。方法 回顾性分析 2016年6月至2018年1月玻璃体切割硅油填充术后的复发性超高度近视MHRD患者10例(10眼),所有患者均由同一术者行巩膜外黄斑外垫压术,将MEDPOR种植体+人造血管+环扎条带制成的“三明治加压块”固定垫压于黄斑区,术后行眼眶CT检查明确加压块位置。术后6~12个月取出硅油。术后随访18个月,观察并记录术后并发症、视网膜脱离复位、黄斑裂孔闭合情况、术后视力、眼轴长度等指标。结果 眼眶CT显示10眼加压块均位于黄斑区;末次随访 SD-OCT示10眼视网膜完全复位,7眼黄斑裂孔完全闭合,3眼黄斑裂孔部分闭合;9眼术后最佳矫正视力(best corrected visual acuity,BCVA)较术前提高,1眼提高不明显;术前患者 BCVA为(1.55±0.26)LogMAR,术后3个月BCVA为(0.99±0.05)LogMAR,与术前比较差异有统计学意义(P<0.001);术前患者眼轴长度为(31.27±1.18)mm,术后3个月为(28.81±0.87)mm,与术前比较差异有统计学意义(P<0.001)。所有患眼均未发生眼底出血、眼内炎、涡静脉回流障碍、眼前部缺血综合征等并发症。结论 巩膜外黄斑外垫压术是治疗硅油填充术后复发性超高度近视MHRD安全有效的手术方法,能提高视网膜解剖复位率、黄斑裂孔闭合率和视力。  相似文献   
26.
27.
综述糖尿病足溃疡复发的影响因素包括足底压力、周围神经病变、周围血管病变、足部外伤、血糖控制不佳及其他(吸烟、日常活动负重、C-反应蛋白水平升高),预防复发的措施包括识别和筛查高危因素、卸载足部压力、选择合适的治疗鞋和鞋垫、手术卸载、自我护理、健康教育、信息化管理、依从性管理等,提出采取多种预防措施的综合性护理干预有助于减少糖尿病足溃疡的复发率。  相似文献   
28.
Photobiomodulation (PBM) therapy is based on the exposure of biological tissues to low‐level laser light (coherent light) or light‐emitting diodes (LEDs; noncoherent light), leading to the modulation of cellular functions, such as proliferation and migration, which result in tissue regeneration. PBM therapy has important clinical applications in regenerative medicine. Vitiligo is an acquired depigmentary disorder resulting from disappearance of functional melanocytes in the involved skin. Vitiligo repigmentation depends on available melanocytes derived from (a) melanocyte stem cells located in the bulge area of hair follicles and (b) the epidermis at the lesional borders, which contains a pool of functional melanocytes. Since follicular melanoblasts (MBs) are derived from the melanocyte stem cells residing at the bulge area of hair follicle, the process of vitiligo repigmentation presents a research model for studying the regenerative effect of PBM therapy. Previous reports have shown favourable response for treatment of vitiligo with a low‐energy helium‐neon (He‐Ne) laser. This review focuses on the molecular events that took place during the repigmentation process of vitiligo triggered by He‐Ne laser (632.8 nm, red light). Monochromatic radiation in the visible and infrared A (IRA) range sustains matrix metalloproteinase (MMP), improves mitochondrial function, and increases adenosine triphosphate (ATP) synthesis and O2 consumption, which lead to cellular regenerative pathways. Cytochrome c oxidase in the mitochondria was reported to be the photoacceptor upon which He‐Ne laser exerts its effects. Mitochondrial retrograde signalling is responsible for the cellular events by red light. This review shows that He‐Ne laser initiated mitochondrial retrograde signalling via a Ca2+‐dependent cascade. The impact on cytochrome c oxidase within the mitochondria, an event that results in activation of CREB (cyclic‐AMP response element binding protein)‐related cascade, is responsible for the He‐Ne laser promoting functional development at different stages of MBs and boosting functional melanocytes. He‐Ne laser irradiation induced (a) melanocyte stem cell differentiation; (b) immature outer root sheath MB migration; (c) differentiated outer root sheath MB melanogenesis and migration; and (d) perilesional melanocyte migration and proliferation. These photobiomodulation effects result in perifollocular and marginal repigmentation in vitiligo.  相似文献   
29.
30.
BACKGROUNDCholangiocarcinoma is a disease with a high mortality rate. Our previous study revealed that cholelithiasis patients who undergo endoscopic sphincterotomy (ES)/endoscopic papillary balloon dilatation are at a higher risk for subsequent cholangiocarcinoma than cholelithiasis patients who undergo cholecystectomy.AIMTo clarify the relationship between recurrent biliary events and subsequent cholangiocarcinoma risk in choledocholithiasis patients.METHODSFrom one million random cases in the Taiwan National Health Insurance Research Database 2004–2011, we selected symptomatic choledocholithiasis patients older than 18 years who were admitted from January 2005 to December 2009 (study group). Cases for a control group were defined as individuals who had never been diagnosed with cholelithiasis, matched by sex and age in a 1:3 ratio. The study group was further divided into ES/endoscopic papillary balloon dilatation, both ES/endoscopic papillary balloon dilatation and cholecystectomy, and no intervention groups.RESULTSWe included 2096 choledocholithiasis patients without previous intervention or cholangiocarcinoma. A total of 12 (2.35%), 11 (0.74%), and 1 (1.00%) subsequent cholangiocarcinoma cases were diagnosed among 511 ES/endoscopic papillary balloon dilatation patients, 1485 patients with no intervention, and 100 ES/endoscopic papillary balloon dilatation and cholecystectomy patients, respectively. The incidence rates of recurrent biliary event were 527.79/1000 person-years and 286.69/1000 person-years in the subsequent cholangiocarcinoma and no cholangiocarcinoma group, showing a high correlation between subsequent cholangiocarcinoma risk and recurrent biliary events.CONCLUSIONCholedocholithiasis patients who undergo further cholecystectomy after ES/endoscopic papillary balloon dilatation have decreased subsequent cholangiocarcinoma risk due to reduced recurrent biliary events.  相似文献   
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