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   2642篇
  免费   135篇
  国内免费   10篇
耳鼻咽喉   41篇
儿科学   87篇
妇产科学   25篇
基础医学   248篇
口腔科学   51篇
临床医学   189篇
内科学   656篇
皮肤病学   44篇
神经病学   229篇
特种医学   290篇
外科学   403篇
综合类   19篇
预防医学   129篇
眼科学   38篇
药学   131篇
中国医学   11篇
肿瘤学   196篇
  2022年   27篇
  2021年   38篇
  2020年   28篇
  2019年   30篇
  2018年   49篇
  2017年   38篇
  2016年   45篇
  2015年   57篇
  2014年   69篇
  2013年   103篇
  2012年   123篇
  2011年   146篇
  2010年   99篇
  2009年   73篇
  2008年   114篇
  2007年   161篇
  2006年   120篇
  2005年   123篇
  2004年   153篇
  2003年   134篇
  2002年   131篇
  2001年   63篇
  2000年   78篇
  1999年   52篇
  1998年   33篇
  1997年   36篇
  1996年   31篇
  1995年   22篇
  1994年   26篇
  1993年   17篇
  1992年   46篇
  1991年   38篇
  1990年   48篇
  1989年   48篇
  1988年   53篇
  1987年   44篇
  1986年   37篇
  1985年   42篇
  1984年   25篇
  1983年   14篇
  1982年   12篇
  1981年   10篇
  1979年   13篇
  1975年   9篇
  1974年   9篇
  1971年   14篇
  1970年   13篇
  1969年   13篇
  1967年   9篇
  1966年   12篇
排序方式: 共有2787条查询结果,搜索用时 15 毫秒
41.
To estimate the changes in regional cerebral blood flow (rCBF) around cerebral arteriovenous malformation (AVM) before and after embolization, 6 patients with AVM were sequentially examined with positron emission tomography (PET). PET depicted the remodeling of rCBF in the ipsilateral hemisphere of AVM after embolization. Decrease of rCBF in the ipsilateral hemisphere was also detected in patients with focal symptoms before embolization, and improvement of clinical symptoms after embolization corresponded to disappearance of rCBF decrease. PET can detect hemodynamic changes after embolization, and has a possibility to estimate the effect of embolization in patients with AVM.  相似文献   
42.
BACKGROUND: The role of changes in peri-operative blood lactate levels in recipients of living-related liver transplants has not yet been clarified. METHODS: Forty-three recipients were included in this study. Blood lactate, plasma total bilirubin, aminotransferase, body temperature, and gastric mucosal PCO2 levels were measured at six time points during surgery: just before the initiation of surgery, just after dissection of the hepatic vasculature, at the end of the anhepatic phase, and 30, 60, and 120 min after reperfusion. We calculated the rate of lactate accumulation during the pre-anhepatic and anhepatic phases and the elimination rate during reperfusion (neohepatic phase), and examined the correlation between these results and the clinical findings. RESULTS: The rate of lactate elimination during the neohepatic phase was correlated with the ratio of graft weight to standard liver volume (P<0.0001). There was also a significant correlation between the rate of lactate accumulation during the pre-anhepatic phase and the preoperative total bilirubin levels (P=0.0008). CONCLUSIONS: Each pre-anhepatic, anhepatic, and neohepatic phase had a characteristic blood lactate profile. The graft size strongly affected lactate levels during the early neohepatic phase.  相似文献   
43.
A 73-year-old man with myasthenia gravis required quadruple coronary artery bypass grafting due to triple-vessel disease. Anesthetic management was performed with general anesthesia using a reduced dose of muscle relaxant with the aid of a neuromuscular transmission monitor. He was extubated 14 hrs after surgery without difficulty under this monitor. His postoperative course was uneventful. A patient with myasthenia gravis who required coronary artery bypass surgery was successfully performed by the deliberate preoperative evaluation of patient's myasthenic and cardiac status, and by the careful perioperative management.  相似文献   
44.
OBJECTIVE: Under the fee-for-service system, the overuse and misuse of perioperative antibiotics have become serious concerns in Japan. The objective of the present study is to investigate practice variations of perioperative antimicrobial prophylaxis between and within hospitals, and to identify any opportunities for improvement. METHODS: We polled 319 surgeons in six specialties employed by 11 teaching hospitals in Japan. We developed questionnaires with vignettes, asking physicians about their practice of antimicrobial prophylaxis in six surgical procedures (gastrectomy, hysterectomy, cataract surgery, clipping of cerebral aneurysm, hip fracture surgery, and coronary artery bypass graft) and utilization of institutional clinical pathways. RESULTS: Average durations of prophylaxis varied by procedure, from 1.6 days for cataract surgery to 5.8 days for clipping surgery. Variation was also observed between institutions for the same procedure, e.g. institutional averages for the duration of prophylaxis for gastrectomy ranged from 2.3 to 7 days. Large intra-institutional variation in prophylaxis duration and inconsistent use of clinical pathways were observed in the cases of gastrectomy, hip fracture surgery, and clipping surgery. At one hospital, 20% of physicians performing gastrectomy indicated the use of an institutional clinical pathway, and prophylaxis duration ranged from 3 to 6 days. For cataract surgery and hysterectomy, clinical pathways were universally applied and intra-institutional practice variation was small, yet prophylaxis duration varied widely between hospitals and third-generation cephalosporins were used extensively. Average length of prophylaxis for hysterectomy ranged from 1.8 to 6 days and 43% of respondents prescribed third-generation cephalosporins. CONCLUSIONS: In Japan, perioperative antimicrobial prophylaxis lacks standardization. Efforts to strengthen an evidence-based approach to antimicrobial prophylaxis need to be made a priority at both the national and institutional levels.  相似文献   
45.
为了检测妇女绝经后发生骨量减少的相关指标进而倡导依据生活方式的特点对绝经后妇女骨质疏松的发生采取相应的预防和护理方针,我们对日本乡村的绝经后妇女(末次月经后六个月或更长时间算起)进行了为期4a的随访。我们运用双能X线骨密度仪(DXA)对腰椎骨密度(BMD)进行检测并对各种变量,包括年龄、绝经时的年龄、骨折史、日常摄奶量以及吸烟习惯进行多元分析,结果表明这些因素对于腰椎骨密度(BMD)的恢复是不相关联的。 在这些变量中,骨折史被证明对于相关人群是最具危险性的,这些对象有高比例的骨量减少(6.6%),其次是不规律的摄奶(13.6%)和吸烟(9.3%)。在护理中使用的作用于足跟骨的检测骨密度的设备被证实与作用于腰椎的DXA设备可以相互替代。依据这些结果,针对居住在日本乡村的绝经后妇女制订了相应的预防骨质疏松的方针。这些卫生指导方针依据特定区域的生活方式而制定并可适用于其他的人群和区域。在本文中,作者列出了不同的有助于预防绝经后妇女出现骨质疏松的方法并进行了调查。  相似文献   
46.
Long-term toluene abuse causes a variety of psychiatric symptoms. However, little is known about abnormalities at the neurochemical level in the living human brain after long-term exposure to toluene. To detect neurochemical changes in the basal ganglia of subjects with a history of long-term toluene use, proton magnetic resonance spectroscopy (1H MRS) was performed in 12 abstinent toluene users and 13 healthy comparisons with no history of drug abuse. N-acetylaspartate (NAA), creatine plus phosphocreatine (Cr + PCr), choline-containing compounds (Cho), and myo-inositol (MI) levels were measured in the left and right basal ganglia. The Cho/Cr + PCr ratio, a marker of membrane metabolism, was significantly increased in the basal ganglia of toluene users in comparison to that of the control subjects. Furthermore, the increase in the Cho/Cr + PCr ratio was significantly correlated with the severity of residual psychiatric symptoms. These findings suggest that long-term toluene use causes membrane disturbance in the basal ganglia, which is associated with residual psychiatric symptoms that persist even after long-term abstinence from toluene use.  相似文献   
47.
BACKGROUND: Obstruction of the St Jude Medical valve (St Jude Medical, Inc, St Paul, Minn) is a rare but serious complication. METHODS: Cineradiographic and echocardiographic evaluations of aortic St Jude Medical valves were simultaneously performed on 54 patients, with no signs of prosthetic valve dysfunction late after surgery. RESULTS: Although closing angles of the leaflets corresponded closely with the manufacturer data, restricted opening of the leaflets (opening angle >/= 20 degrees ) was found in 16 (group D) of the 54 patients by means of cineradiography. The opening angles were equal to or less than 14 degrees in the other 23 patients (group N) and between 15 degrees and 19 degrees in the remaining 15 (group M). Doppler-derived transprosthetic pressure gradients were significantly higher (P =.03) and the velocity index was significantly lower (P =.003) in group D than in group N. However, no significant differences were found in those values between group N and group M. Replacement of the aortic St Jude Medical valves was performed in 5 of the 16 patients, and the remaining 11 have been followed up because of relatively low pressure gradients. The cause of restricted leaflet movement was pannus formation without thrombosis in 4 patients and valve thrombosis with pannus formation in one. CONCLUSIONS: Reduced valve orifice area and restricted opening of the leaflets resulting from excess growth of pannus probably led to obstruction of the aortic St Jude Medical valves. A combination of cineradiography and echocardiography makes it possible to provide an accurate and detailed diagnosis of obstruction of the valve.  相似文献   
48.
49.
50.
Wee1, the Cdc2 inhibitory kinase, needs to be down-regulated at the onset of mitosis to ensure rapid activation of Cdc2. Previously, we have shown that human somatic Wee1 (Wee1A) is down-regulated both by protein phosphorylation and degradation, but the underlying mechanisms had not been elucidated. In the present study, we have identified the beta-transducin repeat-containing protein 1/2 (beta-TrCP1/2) F-box protein-containing SKP1/Cul1/F-box protein (SCF) complex (SCF(beta-TrCP1/2)) as an E3 ubiquitin ligase for Wee1A ubiquitination. Although Wee1A lacks a consensus DS(p)GXXS(p) phospho-dependent binding motif for beta-TrCP, recognition of Wee1A by beta-TrCP depended on phosphorylation, and two serine residues in Wee1A, S53 and S123, were found to be the most important phosphorylation sites for beta-TrCP recognition. We have found also that the major M-phase kinases polo-like kinase 1 (Plk1) and Cdc2 are responsible for the phosphorylation of S53 and S123, respectively, and that in each case phosphorylation generates an unconventional phospho-degron (signal for degradation) that can be recognized by beta-TrCP. Phosphorylation of Wee1A by these kinases cooperatively stimulated the recognition and ubiquitination of Wee1A by SCF(beta-TrCP1/2) in vitro. Mutation of these residues or depletion of beta-TrCP by small-interfering RNA treatment increased the stability of Wee1A in HeLa cells. Moreover, our analysis indicates that beta-TrCP-dependent degradation of Wee1A is important for the normal onset of M-phase in vivo. These results also establish the existence of a feedback loop between Cdc2 and Wee1A in somatic cells that depends on ubiquitination and protein degradation and ensures the rapid activation of Cdc2 when cells are ready to divide.  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