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   6179篇
  免费   421篇
  国内免费   28篇
耳鼻咽喉   26篇
儿科学   91篇
妇产科学   95篇
基础医学   875篇
口腔科学   95篇
临床医学   700篇
内科学   1415篇
皮肤病学   69篇
神经病学   832篇
特种医学   204篇
外科学   912篇
综合类   41篇
预防医学   362篇
眼科学   111篇
药学   445篇
中国医学   14篇
肿瘤学   341篇
  2023年   25篇
  2022年   64篇
  2021年   137篇
  2020年   75篇
  2019年   123篇
  2018年   170篇
  2017年   107篇
  2016年   109篇
  2015年   135篇
  2014年   185篇
  2013年   275篇
  2012年   439篇
  2011年   457篇
  2010年   260篇
  2009年   247篇
  2008年   410篇
  2007年   423篇
  2006年   421篇
  2005年   423篇
  2004年   381篇
  2003年   355篇
  2002年   335篇
  2001年   84篇
  2000年   73篇
  1999年   78篇
  1998年   82篇
  1997年   76篇
  1996年   50篇
  1995年   59篇
  1994年   48篇
  1993年   47篇
  1992年   32篇
  1991年   30篇
  1990年   33篇
  1989年   19篇
  1988年   21篇
  1987年   20篇
  1986年   17篇
  1985年   21篇
  1984年   23篇
  1983年   15篇
  1982年   25篇
  1981年   19篇
  1979年   16篇
  1978年   19篇
  1977年   15篇
  1976年   13篇
  1975年   14篇
  1974年   18篇
  1973年   13篇
排序方式: 共有6628条查询结果,搜索用时 31 毫秒
991.
992.

Background

Occlusion of the left atrial appendage (LAA) is a potential alternative to anticoagulation for patients with atrial fibrillation (AF); however, evidence of its safety and efficacy is lacking. The Left Atrial Appendage Occlusion Study II (LAAOS II) explored the feasibility of a definitive trial of LAA occlusion for stroke prevention in AF.

Methods

A cross-sectional study of 1889 consecutive patients undergoing cardiac surgery was performed to determine the prevalence of AF and risk factors for stroke. We also randomized 51 patients with AF and increased stroke risk to LAA occlusion (n = 26) or no occlusion and oral anticoagulation (n = 25) to assess the rate of recruitment and the safety of LAA amputation.

Results

In the cross-sectional study, 204 patients (10.8%) had AF and 98 (5.2%) met trial eligibility. Fifty-one patients were recruited into the trial at a rate of 1.6 patients per centre per month. No patient with occlusion had significant bleeding at the LAA site. At 1 year, 4 patients (15.4%) in the occlusion arm and 5 patients (20.0%) in the no-occlusion arm experienced death, myocardial infarction (MI), stroke, noncerebral systemic emboli, or major bleeding (relative risk [RR], 0.71; 95% confidence interval [CI], 0.19-2.66; P = 0.61). The predominant component of the composite was stroke, with 1 in the occlusion arm and 3 in the no-occlusion arm.

Conclusions

LAA occlusion can be safely performed at the time of cardiac surgery. A large trial to evaluate the clinical efficacy of LAA occlusion in patients undergoing cardiac surgery is possible in motivated centres with some modifications to the design of LAAOS II.  相似文献   
993.
994.
The present study aims to determine if an in vivo rat model of drug–drug interaction (DDI) could be useful to discriminate a sensitive (buspirone) from a ‘non‐sensitive’ (verapamil) CYP3A substrate, using ketoconazole and ritonavir as perpetrator drugs. Prior to in vivo studies, ketoconazole and ritonavir were shown to inhibit midazolam hydroxylation with IC50 values of 350 ± 60 nm and 11 ± 3 nm , respectively, in rat liver microsomes (RLM). Buspirone and verapamil were also shown to be substrates of recombinant rat CYP3A1/3A2. In the rat model, the mean plasma AUC0‐inf of buspirone (10 mg/kg, p.o.) was increased by 7.4‐fold and 12.8‐fold after co‐administration with ketoconazole and ritonavir (20 mg/kg, p.o.), respectively. The mean plasma AUC0‐inf of verapamil (10 mg/kg, p.o.) was increased by 3.0‐fold and 4.8‐fold after co‐administration with ketoconazole and ritonavir (20 mg/kg, p.o.), respectively. Thus, the rat DDI model correctly identified buspirone as a sensitive CYP3A substrate (>5‐fold AUC change) in contrast to verapamil. In addition, for both victim drugs, the extent of DDI when co‐administered was greater with ritonavir compared with ketoconazole, in line with their in vitro CYP3A inhibition potency in RLM. In conclusion, our study extended the rat DDI model applicability to two additional victim/perpetrator pairs. In addition, we suggest that use of this model would increase our confidence in estimation of the DDI potential for victim drugs in early discovery. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
995.
996.
997.
How beneficial is the provision of information leaflets to low back pain patients before steroid injection under fluoroscopy? OBJECTIVES: To compare the value of information leaflets with verbal information on steroid injection under fluoroscopy. METHODS: Alternate month design. One hundred and twenty-three low back pain patients hospitalized for steroid injection under fluoroscopy were enrolled in the trial. Fifty-two patients received both written standardized information and non-standardized verbal information (intervention group), seventy one patients received only non-standardized verbal information (control group). Anxiety assessed at baseline evaluation and just before the injection; satisfaction related to the information received assessed on discharge day; knowledge about steroid injection assessed 4 hours and 1 month after the injection. RESULTS: Patients had a high anxiety level at baseline evaluation. Written standardized information did not decrease significantly anxiety (P = 0.068) before the injection, had no effect on pain during the injection, but increased patients' knowledge about the adverse effects on the day of injection and 1 month later (P = 0.040 and P = 0.084 respectively), and improve satisfaction with information received about potential complications of the steroid injections (P = 0.018). CONCLUSIONS: Providing an information leaflet to low back pain patents undergoing steroid injection under fluoroscopy tends to reduce state anxiety, and increases patients' knowledge and satisfaction with information about the risks of the injection.  相似文献   
998.
The burden of neurological diseases in western societies has accentuated the need to develop effective therapies to stop the progression of chronic neurological diseases. Recent discoveries regarding the role of the immune system in brain damage coupled with the development of new technologies to manipulate the immune response make immunotherapies an attractive possibility to treat neurological diseases. The wide repertoire of immune responses and the possibility to engineer such responses, as well as their capacity to promote tissue repair, indicates that immunotherapy might offer benefits in the treatment of neurological diseases, similar to the benefits that are being associated with the treatment of cancer and autoimmune diseases. However, before applying such strategies to patients it is necessary to better understand the pathologies to be targeted, as well as how individual subjects may respond to immunotherapies, either in isolation or in combination. Due to the powerful effects of the immune system, one priority is to avoid tissue damage due to the activity of the immune system, particularly considering that the nervous system does not tolerate even the smallest amount of tissue damage.  相似文献   
999.
STUDY OBJECTIVES: Chronic primary insomnia has been hypothesized to result from conditioned arousal or the inability to initiate normal sleep processes. The event-related potentials (ERPs) N1, P2, and N350 are useful indexes of arousal. The objective is to compare these ERPs in primary chronic psychophysiological insomniacs (INS) and good sleepers (GS) during multiple recordings. PARTICIPANTS: Participants were 15 INS (mean age = 46 years, SD = 7.5) and 16 GS (mean age = 37 years, SD = 10.1). METHODS AND PROCEDURE: Following a multistep clinical evaluation, INS and GS participants underwent 4 consecutive nights of PSG recordings (N1 to N4). ERPs were recorded on the 3rd and 4th nights in the sleep laboratory (N3 and N4). ERPs recordings were made during wake on both nights (in the evening and upon awakening), with the addition of sleep-onset recordings on N4. Auditory stimuli consisted of "standard" and "deviant" tones. STATISTICAL ANALYSIS: Repeated measures ANOVAs were computed for each ERP for each recording for each type of stimulus. RESULTS: The amplitude of P2 and N350 was greater for the deviant than for the standard stimulus in both groups. The amplitude of N1 was larger in INS than GS in the morning and the evening. While the amplitude of N350 was larger in GS than in INS at sleep onset, the amplitude of P2 was greater in INS than in GS at that time. CONCLUSION: Signs of greater cortical arousal in psychophysiological insomnia individuals are observed, especially upon awakening in the morning. However, at sleep onset, difficulties from disengaging from wake processes and some inability at initiating normal sleep processes appear also present in individuals with insomnia compared to good sleepers.  相似文献   
1000.
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