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   947篇
  免费   53篇
  国内免费   3篇
耳鼻咽喉   7篇
儿科学   24篇
妇产科学   24篇
基础医学   76篇
口腔科学   32篇
临床医学   137篇
内科学   232篇
皮肤病学   83篇
神经病学   17篇
特种医学   3篇
外科学   174篇
综合类   30篇
一般理论   1篇
预防医学   48篇
眼科学   8篇
药学   69篇
中国医学   23篇
肿瘤学   15篇
  2021年   6篇
  2020年   2篇
  2019年   6篇
  2018年   7篇
  2017年   16篇
  2016年   14篇
  2015年   30篇
  2014年   45篇
  2013年   48篇
  2012年   32篇
  2011年   23篇
  2010年   101篇
  2009年   123篇
  2008年   43篇
  2007年   34篇
  2006年   58篇
  2005年   22篇
  2004年   5篇
  2003年   13篇
  2002年   9篇
  2001年   3篇
  2000年   3篇
  1999年   9篇
  1998年   23篇
  1997年   48篇
  1996年   41篇
  1995年   28篇
  1994年   19篇
  1993年   19篇
  1992年   15篇
  1991年   16篇
  1990年   11篇
  1989年   10篇
  1988年   6篇
  1987年   13篇
  1986年   8篇
  1985年   2篇
  1984年   10篇
  1983年   7篇
  1981年   4篇
  1980年   2篇
  1979年   2篇
  1978年   2篇
  1975年   2篇
  1959年   9篇
  1958年   17篇
  1957年   9篇
  1956年   9篇
  1955年   2篇
  1954年   9篇
排序方式: 共有1003条查询结果,搜索用时 15 毫秒
61.
Background: There are insufficient data as to the influence of the head and neck flexion, extension, and rotation on the ventilation with laryngeal tube suction II® (LTS II). The purpose of this study was to investigate the influence of the head and neck position on oropharyngeal sealing pressure (primary outcome) and ventilation score (secondary outcome) during ventilation with the LTS II in children. Methods: We studied 33 children scheduled for elective surgery. Oropharyngeal sealing pressure and ventilation score were measured with the head and neck in a neutral position, flexed, extended and rotated to the right. The ventilation score was scored from 0 to 3 based on three items (no leakage with an airway pressure of 15 cmH2O, bilateral chest excursion, and a square wave capnogram; each item scored 0 or 1 point). Peak inspiratory pressure (PIP) at a tidal volume of 10 ml·kg?1 and fiberoptic laryngeal views were also assessed in each position. Results: Although the sealing pressure was lower in the extended position [22 (8) cmH2O] than that in the neutral position [25 (7) cmH2O], there was no significant leakage during ventilation with a tidal volume of 10 ml·kg?1. In the neutral, extended and rotated positions, the median ventilation scores were better (3 point respectively) than that with the head and neck flexed (1 point). PIP was decreased with the head and neck extended or rotated but was significantly increased in flexion position. During fibreoptic examination, the vocal cords were more easily seen in extension and right rotation, compared with the neutral position and flexion. Conclusions: Although oropharyngeal sealing pressure is decreased with the head and neck extended, effective ventilation with LTS II can be performed like in the neutral position or the rotated position. While the sealing pressure is maintained with the head and neck flexed, flexion compromises the ventilation with LTS II in children.  相似文献   
62.
63.
Background: It is known that patients with lifesaving devices such as implantable cardioverter-defibrillators (ICDs) may be alarmed and worried by recalls or alerts related to their ICDs.
Objectives: This study aimed to determine whether counseling has any short- or long-term benefits, and to look for characteristics that identify those most worried and those most in need of counseling.
Methods: Among 100 patients with recall or alert ICDs, 14 were pacer dependent; 50 had ICDs for 1° prevention and 22 were women. Patients completed a survey indicating how worried they were on learning of the recall or alert (0–10 scale). After counseling and advice in accordance with manufacturer guidelines, patients were asked to indicate their level of worry, and were again asked after 6 months.
Results: For all patients, the "worry level" at the initial interview was 5.0 ± 3.7, falling to 2.2 ± 3.0 after counseling (P < 0.001) and 1.4 ± 2.3 after 6 months (P < 0.001 vs both earlier levels). There were no significant differences between those implanted for 1° versus 2° prevention or for pacer dependency. Women were initially more worried than men, but not for the long term. The 49 patients whose ICDs could be managed by reprogramming or software fix had significant reduction in worry after counseling and at 6 months compared to others. The 18 patients recommended for operative intervention remained more concerned after counseling (3.5 ± 3.3 vs 1.9 ± 2.9, P = 0.043).
Conclusions: Patients' concerns resulting from ICD recalls or alerts can be reduced by appropriate counseling. Those patients whose ICDs could be reprogrammed to safer parameters had the most reduction in worry levels.  相似文献   
64.
目的探索肾虚骨质疏松症的病理机制,研究补肾中药对肾虚骨质疏松大鼠防治作用的机理。方法实验采用去双侧卵巢的方法,建立肾虚骨质疏松症模型。补肾中药复方(高、中、低)剂量对实验大鼠治疗12周,以骨疏康颗粒、盖天力牡蛎钙作为阳性对照药,并设正常对照组和模型空白组。用RT-PCR法、Western印迹法检测肾虚骨质疏松症大鼠下丘脑组织中BMP-4、Smad6 mRNA和蛋白表达。结果①与正常组比较,模型空白组大鼠下丘脑组织中的BMP-4 mRNA和蛋白表达水平明显增强;Smad6 mRNA和蛋白表达水平明显降低。②与模型空白组比较,补肾中药组对模型大鼠下丘脑组织中的BMP-4 mRNA和蛋白表达明显降低;而Smad6 mRNA和蛋白表达明显增强。结论肾虚骨质疏松症的病理机制为肾精不足,骨髓、脑髓失养,表现在下丘脑-垂体-靶腺轴的调控失常,包括下丘脑组织的细胞因子及其信号传导通路的异常。  相似文献   
65.
66.
Opinions vary regarding the need to perform defibrillation testing prior to hospital discharge in recipients of state-of-the-art cardioverter defibrillators (ICDs). Our protocol is to perform predischarge ICD testing 1 day after implant. This report includes 682 consecutive implants. Adverse observations at testing were grouped into (1) risk of defibrillation failure, (2) surgical complications, (3) sensing/pacing issues or narrow defibrillation margin warranting closer follow-up, or (4) findings correctable by device reprogramming. Among the 682 patients, 63% had single-chamber and 37% dual-chamber or biventricular ICDs. In 48 patients (7%) there were 69 concerns and/or interventions, with overlaps among the four categories, including one failure to defibrillate (0.15%), and six other patients at risk. Surgical complications included 11 hematomas (1.6%), and six lead dysfunctions. Closer follow-up was indicated in 19 patients (2.7%), for high pacing thresholds in seven, sensing issues in seven, and <10 J defibrillation margin in five. Device reprogramming was needed in 31 patients (4.5%), for tachycardia detection and therapy settings in 12, and for pacing/sensing functions in 22 patients. In eight patients ventricular fibrillation could not be induced. There was no morbidity or mortality due to testing. The state-of-the-art ICDs delivering biphasic shocks are remarkably reliable. The routine pre-hospital discharge defibrillation testing of such ICDs may be optional and left to the physicians' discretion.  相似文献   
67.
The actuarial life-table is commonly used to describe lifetime data of living subjects and manufactured products. The life-table method allows subjects to come under observation at different times and, thus, to have differing lengths of follow-up, by assuming all subjects begin their lifetimes relative to the outcome of interest at some common point in time. As time progresses, subjects are withdrawn from the life-table when their period of observation has elapsed. This pattern of follow-up is often termed "right-censoring." An important feature of the classical life table approach is that the time at which the subject is placed at risk is known, and the status relative to the outcome of interest is known for the entire time at risk. Sometimes, however, subjects cannot be observed for some period after the beginning of their lifetimes. The example to be considered involves follow-up data collected by a commercial pacemaker monitoring service, to which patients subscribe, generally at some point following the actual implant of the pacemaker. Since the outcome of interest is device failure after implant, some means of dealing with the lack of information between implant and initiation of follow-up is needed. The extension of the actuarial life-table to accommodate this "left-censoring" will be described in this paper.  相似文献   
68.
The value of programmed electrical stimulation (PES) and Holter monitoring in the assessment of amiodarone efficacy was reviewed. Many physicians have been disturbed by the persistent inducibility of arrhythmias in patients treated with amiodarone, who nevertheless do very well during the follow-up period. Noninducibility was associated with a favorable prognosis among 366 VT patients. Eighty-eight (24%) were noninducible on amiodarone, and 10% of these had recurrences, vs 39% in patients who remained inducible. Further, increased difficulty of induction with PES or induction of a slower or better tolerated VT may indicate a favorable outlook, and add to the value of PES. Few papers rigorously employed Holter monitoring in the assessment of amiodarone. In general, suppression of previously frequent arrhythmias implies excellent protection for patients with benign arrhythmias and moderate protection with malignant arrhythmias. By Holter assessment in 186 VT patients, arrhythmias were suppressed in 114 (61%), and 18% of these had recurrences vs 50% in patients whose arrhythmias were not suppressed. Studies attempting to correlate the results of PES and Holter monitoring in the same patients are lacking and may prove useful.  相似文献   
69.
Fas‐mediated apoptosis is considered a principal pathway for apoptosis induction in normal and cancer cells. Expression of Fas has been reported in prostate tissues several times, but the data were not consistent. Expression of FLICE‐like inhibitory protein (FLIP), an inhibitor of Fas‐mediated apoptosis, has not been studied by immunohistochemistry in prostate tissues. The aim of this study is to explore whether alterations of Fas and FLIP expression occur in prostate cancer tissues. We analyzed the expression of Fas and FLIP in 107 prostate adenocarcinoma tissues by immunohistochemistry using a tissue microarray approach. Normal glandular cells of the prostates strongly expressed both Fas and FLIP proteins. Prostate intraepithelial neoplasm also showed a strong Fas immunoreacitity. Fas expression was strongly positive in 60 cancers (56.1%), but the remaining 47 cancers showed no (6.5%) or markedly decreased (37.4%) Fas immunostaining compared with the normal glandular cells of the same patients. By contrast, FLIP expression was strong in most (103/107; 96.3%) of the cancers, and only four cancers (3.7%) showed decreased immunoreactivities compared with the normal cells. The decreased expression of Fas was not associated with pathologic characteristics, including FLIP expression, size of the cancers, age, Gleason score and stage. The decreased expression of Fas in a large fraction of prostate cancers compared with their normal cells suggested that loss of Fas expression might play a role in tumorigenesis in some prostate cancers possibly by inhibiting apoptosis mediated by Fas.  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