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   2146篇
  免费   64篇
  国内免费   9篇
耳鼻咽喉   29篇
儿科学   26篇
妇产科学   30篇
基础医学   366篇
口腔科学   74篇
临床医学   145篇
内科学   465篇
皮肤病学   39篇
神经病学   82篇
特种医学   40篇
外科学   420篇
综合类   5篇
预防医学   79篇
眼科学   16篇
药学   175篇
中国医学   12篇
肿瘤学   216篇
  2023年   9篇
  2022年   23篇
  2021年   38篇
  2020年   16篇
  2019年   32篇
  2018年   23篇
  2017年   20篇
  2016年   32篇
  2015年   32篇
  2014年   67篇
  2013年   65篇
  2012年   114篇
  2011年   115篇
  2010年   60篇
  2009年   54篇
  2008年   105篇
  2007年   115篇
  2006年   126篇
  2005年   110篇
  2004年   104篇
  2003年   95篇
  2002年   88篇
  2001年   85篇
  2000年   95篇
  1999年   99篇
  1998年   28篇
  1997年   29篇
  1996年   25篇
  1995年   22篇
  1994年   7篇
  1993年   21篇
  1992年   44篇
  1991年   31篇
  1990年   36篇
  1989年   40篇
  1988年   33篇
  1987年   31篇
  1986年   33篇
  1985年   20篇
  1984年   18篇
  1983年   8篇
  1981年   4篇
  1979年   11篇
  1978年   8篇
  1977年   6篇
  1975年   4篇
  1974年   7篇
  1973年   5篇
  1971年   4篇
  1967年   5篇
排序方式: 共有2219条查询结果,搜索用时 15 毫秒
61.
A 69-year-old man with stage III lung squamous cell carcinoma developed immune-related hepatitis following treatment with durvalumab, and was given high-dose corticosteroids and immunosuppressive drugs (mycophenolate mofetil, azathioprine, tacrolimus) but without demonstrating any improvement. Two cycles of infliximab (5 mg/kg) were then administered and thereafter the hepatitis improved. At the time of writing (9 months after the initiation of first course of durvalumab), the patient is alive without either any hepatitis symptoms nor any lung cancer progression. Infliximab may be effective for treating non-small cell lung cancer (NSCLC) patients who develop immunosuppressive drug-resistant immune-related hepatitis caused by durvalumab.  相似文献   
62.
Serum in the culture medium is one crucial factor that compromises RNAi efficiency of non-viral vectors. However, mechanistic roles of serum in siRNA delivery remain unknown. In this work, we took one cationic polymer, pullulan chemically modified by spermine (termed as pullulan-spermine, Ps), as a siRNA carrier model to investigate the effects of serum on key steps in siRNA delivery including formation of Ps and siRNA polyplexes (Ps-siRNA), cellular uptake, lysosomal escape, and cytotoxicity. We demonstrate that low serum concentration (1.25% and 2.5%) in culture medium results in large particles of Ps-siRNA, while high serum concentration (10%–40%) leads to small particles of Ps-siRNA. The larger particles initiated the internalization of siRNA more effectively in comparison to the smaller ones. The engulfed Ps-siRNA particles mainly locate in lysosomes. The large particles exhibited stronger abilities of destabilizing lysosomes than that of the small particles as large Ps-siRNA particles contain more amines and subsequently elicit a stronger proton sponge effect which results in more effective lysosomal escape of siRNA. Despite the lower RNAi efficiency, the small particle of Ps-siRNA in the high serum medium generates much lower cytotoxicity. These findings explain why serum significantly affects RNAi and also propose a strategy for improving RNAi efficiency and safety by modulating serum concentration and enhancing lysosomal destabilization.  相似文献   
63.
64.
BackgroundManagement of pacemaker (PM) infections among advanced aged patients possesses particular clinical challenges due to higher rates of concurrent cardiovascular disease and medical comorbidities. Novel leadless cardiac pacemakers (LCPs) may provide new opportunities for better management options in this population, however, there is limited data especially in Asian populations to guide the decision making.MethodsWe reviewed 11 octogenarians (median age: 86 [minimum 82–maximum 90] years; male: 73%; median body mass index (BMI): 20.1 kg/m2) who received Micra Transcatheter Pacing System (Medtronic Inc, Minneapolis, MN) implantations following transvenous lead extractions (TLEs) for PM infections. ResultsAll patients had more than two medical comorbidities (average 3.7 comorbidities). The indications for LCP implantations were atrioventricular block in four patients, atrial fibrillation bradycardia in five, and sinus node dysfunction in two. Eight patients (73%) were bridged with temporary pacing using active fixation leads (median interval of 14.0 days), while one with severe dementia underwent a concomitant LCP implantation and TLE during the same procedure. Successful TLEs and LCP implantations were successfully accomplished in all without any complications. The median time from the TLE procedure to discharge was 22 days (minimum 7–maximum 136). All patients remained free of infections during a mean follow-up period of 17.2 ± 6.5 months.ConclusionsLCP implantations were safe and effective after removing the entire infectious PM system in all octogenarians. The novel LCP technology may offer an alternative option for considering a re-implantation strategy after transvenous PM infections in elderly patients, particularly those with severe frailty and PM dependency.

The incidence of cardiac pacemaker (PM) infections among patients with an advanced age has been increasing owing to the continually widening indications and growing number of generator replacements.[13] In current clinical practice, there is a class l indication for removing all hardware in the case of a proven or suspected device infection, and after a recovery window, a new conventional PM is implanted in PM dependent patients.[1,4,5] However, this management for the elderly population is one of the most sensitive issues, since they possess particular clinical challenges due to higher rates of concurrent cardiovascular disease and medical comorbidities.[610]Recently, the implantation of a Micra Transcatheter Pacing System (Medtronic Inc, Minneapolis, MN) has emerged as a new option for PM re-implantations after the removal of infectious PMs.[1117] Without the use of leads and a device pocket, this leadless cardiac pacemaker (LCP) potentially reduces the risk of pocket infections and lead associated endocarditis.[16,17] However, there have not been enough data supporting the feasibility of leadless PM implantations following the removal of infectious PMs in people with an older age, particularly in octogenarians. Furthermore, there has been no data regarding those therapeutic strategies in Asian populations who have a low body mass index (BMI) and are at a higher risk of a transvenous lead extraction (TLE) procedure. Therefore, in this case series, we sought to characterize the procedure for LCP implantations following TLEs of infected PMs in octogenarians at 2 Japanese high-volume centers.  相似文献   
65.
66.
BACKGROUND AND PURPOSE: Stroke mortality in Japan has significantly declined during recent decades. To determine the cause of this decrease, we studied the trends in stroke incidence and case fatality within 28 days after stroke in a rural area in Japan. METHODS: We used a population-based registry during 1977-1991 in Oyabe, a rural area in the central part of Japan. The average population aged 25 years and older numbered 32 859 persons. Changes in age-standardized stroke incidence rate were calculated and compared between the 3 periods 1977-1981, 1982-1986, and 1987-1991. The 28-day case fatality rate was evaluated and also compared between the 3 periods by onset year. RESULTS: The total number of strokes was 2068. The age-standardized incidence rate of all strokes decreased during the 15-year period, from 605 to 417 per 100 000 in men and from 476 to 329 per 100 000 in women. A marked decline was found during 1977-1986 but was not apparent during 1987-1991. Moreover, there was an increase in the group aged 75 years and older. The 28-day case fatality rates for all strokes improved from 18.0% to 14.2% in men and from 26.8% to 19.1% in women during the observation period. CONCLUSIONS: These data indicate that declines in the stroke incidence and the 28- day case fatality have been associated with a marked decrease in stroke-related mortality in Japan.  相似文献   
67.
We reappraised biochemical hepatitis C activity in hemodialysis patients in comparison with normal controls. A total of 111 hemodialysis patients and 66 healthy volunteer blood donors with hepatitis C virus (HCV) infection were consecutively enrolled. Serum alanine aminotransferase (ALT) levels were normal (< or =45 U/L) in 103 (93%) hemodialysis patients and 34 (52%) donors (p < 0.001). HCV viremic levels were lower in the hemodialysis group (p = 0.044), with no difference in the HCV genotype prevalence. During two-year follow-up, 60 (67%) of 90 hemodialysis patients and 13 (26%) of 50 donors showed persistently normal ALT levels (p < 0.001). For hemodialysis patients, however, the upper normal limit of ALT activity was reset at 25 U/L corresponding to the mean + 2 x SD for the normalized ALT distribution in 400 control patients. The adjusted ALT levels were initially normal in 73 (66%) hemodialysis patients and persistently normal in 19 (21%). Thus, ALT levels were the same for the two groups. GB virus C (GBV-C)/hepatitis G virus (HGV) coinfection found only in the hemodialysis group (10/111) had no influence on the disease. A relationship was noted between low disease activity and female gender in both groups. These findings indicate that biochemical hepatitis C activity in hemodialysis patients is similar to that in normal controls and should be monitored based on adjusted ALT levels.  相似文献   
68.
Although implantation of multipotent bone marrow-derived stem cells represents an attractive new cell therapy to repair damaged tissues, recent reports have raised serious concerns over the feasibility of using stem cells deriving from the bone marrow to promote cell transdifferentiation. We established transgenic (Tg) rats with reporter genes as specific molecular tags to examine the effect of bone marrow cells (BMCs) on transdifferentiation into tissues/organs. To monitor transdifferentiation events of locally transplanted BMCs into hepatocytes or capillary endothelial cells, a liver injury model and an ischemic hind-limb model were developed in rats. To test the ability of circulating bone marrow-derived cells to give rise to myocytes after skeletal muscle injury, we used a bone marrow cell transplantation model from Tg rats, which showed ubiquitous expression of beta-galactosidase (lacZ), into lethally irradiated non-Tg rats. Our results show that there was little transdifferentiation of BMCs into the targeted cells in these tissue injury models. However, in the ischemic hind-limb model, laser Doppler imaging and histologic analysis showed that both implantation of BMCs and treatment with microspheres incorporating basic fibroblast-like growth factor (bFGF), which enables the release of bFGF at the site of action over a period of time, effectively induced angiogenesis. In conclusion, rat BMCs with specific marker genes could be a useful tool for detecting transdifferentiation events in vivo.  相似文献   
69.
Therapeutic angiogenesis is a promising approach to treat ischemic skin flaps. We delivered basic fibroblast growth factor (bFGF) to the recipient bed of a rat dorsal skin flap by a drug delivery system with acidic gelatin hydrogel microspheres (AGHMs), and assessed augmentation of neovascularization and flap viability. An axial skin flap was elevated on the back of male Sprague–Dawley rats, and bFGF solution or bFGF-impregnated AGHMs were injected into the recipient bed. The dose of bFGF in the bFGF solution was set to 15 (Sol-15 group), 50 (Sol-50 group), or 150 μg (Sol-150 group). Correspondingly, 2 mg AGHMs were impregnated with 15 (AGHM-15 group), 50 (AGHM-50 group), or 150 μg (AGHM-150 group) bFGF. Other groups of animals received phosphate-buffered saline (Sol-Cont group) or phosphate-buffered saline-impregnated AGHMs (AGHM-Cont group) as controls. Seven days later, analyses of the area of necrosis, microangiographic findings, and histological findings in the flap were carried out. The area of necrosis in the AGHM-150 group was significantly smaller than that in the other groups. Microangiographic and histological analyses showed that neovascularization of the ischemic skin flap significantly increased in the AGHM-150 group as compared with the Sol-150 group and the AGHM-Cont group. These findings suggest that continuous delivery of bFGF to the recipient bed by bFGF-impregnated AGHMs enhances the viability of an ischemic skin flap.  相似文献   
70.
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