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   1020篇
  免费   84篇
  国内免费   5篇
耳鼻咽喉   6篇
儿科学   45篇
妇产科学   9篇
基础医学   105篇
口腔科学   68篇
临床医学   128篇
内科学   118篇
皮肤病学   9篇
神经病学   50篇
特种医学   201篇
外科学   71篇
综合类   90篇
预防医学   81篇
眼科学   4篇
药学   47篇
中国医学   24篇
肿瘤学   53篇
  2022年   6篇
  2020年   7篇
  2019年   5篇
  2018年   20篇
  2017年   16篇
  2016年   12篇
  2015年   16篇
  2014年   31篇
  2013年   54篇
  2012年   49篇
  2011年   48篇
  2010年   50篇
  2009年   39篇
  2008年   48篇
  2007年   56篇
  2006年   27篇
  2005年   22篇
  2004年   11篇
  2003年   13篇
  2002年   15篇
  2001年   13篇
  2000年   7篇
  1999年   21篇
  1998年   56篇
  1997年   47篇
  1996年   37篇
  1995年   23篇
  1994年   28篇
  1993年   29篇
  1992年   13篇
  1991年   15篇
  1990年   11篇
  1989年   21篇
  1988年   26篇
  1987年   22篇
  1986年   17篇
  1985年   21篇
  1984年   12篇
  1983年   11篇
  1982年   12篇
  1981年   11篇
  1980年   12篇
  1978年   9篇
  1977年   10篇
  1976年   11篇
  1975年   9篇
  1974年   5篇
  1969年   3篇
  1967年   4篇
  1949年   3篇
排序方式: 共有1109条查询结果,搜索用时 15 毫秒
1.
In order to study the involvement of NMDA-receptor activation in brain development, rat pups were chronically treated with the non-competitive NMDA antagonist MK-801 during the neonatal period. We recorded the cortical EEG at various vigilance states throughout the treatment period. Spectral analysis of the EEG showed reduced power in the delta (delta) frequency range (1.5-4 Hz) during quiet sleep and less power in the theta (theta) range (4-7 Hz) during REM-sleep in MK-801 animals than in controls. No significant differences were found for the total time spent in each of the different vigilance states. We conclude that chronic MK-801 treatment probably causes a developmental retardation in state-related brain activities.  相似文献   
2.
Ruggieri  PM; Laub  GA; Masaryk  TJ; Modic  MT 《Radiology》1989,171(3):785-791
The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study.  相似文献   
3.
BACKGROUND: In general practice, acute sinusitis is frequently diagnosed and treated with antibiotics. OBJECTIVE: This study aimed to determine the evidence for the effectiveness of antibiotic treatment in acute maxillary sinusitis in adults by assessing the methodological quality of placebo-controlled double-blind randomized trials. METHOD: An evaluation by four raters through a 35-item scoring-scale for internal and external validity of all placebo-controlled double-blind randomized trials on acute sinusitis found between January 1966 and July 1996. RESULTS: Eighty-five trials were excluded because they were not placebo-controlled, double-blind, randomized, or were carried out in patients with chronic sinusitis or in children. The three remaining trials were performed in different populations (one in general practice) between 1973 and 1978. Only one study claimed superiority of antibiotic treatment. Different inclusion criteria and major outcome measures were used by the authors. The reliability of major outcome events was reported poorly or not at all and in two studies outcome measures were clinically inappropriate. The studies scored 30-62% of the maximum attainable score for internal validity and 10-20% for external validity. CONCLUSION: The effectiveness of antibiotic treatment in acute maxillary sinusitis in a general practice population is not based sufficiently on evidence.   相似文献   
4.
5.
Co-existence of facial and occipital pain may occur in occipital neuralgia, migraine and cluster headache; suggesting convergence of trigeminal and cervical afferents. Such convergence has been shown in humans and other animals, but the site and extent of this are uncertain. In anaesthetized adult cats, the superior sagittal sinus and occipital nerve were stimulated electrically, and extracellular recordings made in the dorsolateral area of the upper cervical cord using glass-coated tungsten electrodes. Of 49 units in 10 cats, 33 (67%) had input from the superior sagittal sinus and the occipital nerve. Thirteen (27%) had superior sagittal sinus input and 3 (6%) had occipital nerve input. Convergent receptive fields were identified mechanically in 7 units. These experiments in cats show convergent input from occipital nerve and superior sagittal sinus on dorsolateral area units in two-thirds of cases studied. This experimental site of trigeminocervical convergence may relate to referral of pain in occipital neuralgia and other headaches.  相似文献   
6.
In patients with PG-dependent renal function, NSAID administration constantly reduces GFR and RBF in a dose-dependent fashion. In this situation, the risk of overt acute renal failure is high and should be taken into proper account. In contrast, the incidence of NSAID-related renal structural alterations appears to be very low, yet the absolute number of patients may be significant considering the wide use of such drugs. Concerning the antiproteinuric effect of NSAIDs, the unfavourable ratio risk/benefit does not seem to support their indication in proteinuric nephropathies. The development of PGHS-2 selective inhibitors is promising, and may open new therapeutical strategies in the treatment of the progression of renal disease.   相似文献   
7.
8.
9.
This paper reports a study which aimed to develop an understanding of newly registered nurses' attitudes, knowledge, confidence and educational needs in relation to cancer care. An educational intervention designed to meet these nurses' needs was then developed and evaluated with 127 newly registered nurses from two general hospitals. Nurses attended two different educational interventions; one group of nurses completing a 3 day experiential workshop; and a second group attended a more formal seminar programme. A third group of nurses who were unable to obtain study leave were followed up as a control group. A triangulation strategy was used to collect data from different sources, and included a baseline study, and a study of nurses before, after and 3 months following the educational interventions. Data from the study revealed the perceived need and desire for more education on cancer care, and the strong association of cancer with death amongst newly registered nurses. Significant benefits to those nurses attending the workshop were demonstrated. These differences were however less obvious at 3 months follow-up.  相似文献   
10.
Bile duct calculi in patients with primary sclerosing cholangitis   总被引:1,自引:0,他引:1  
  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