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   815篇
  免费   55篇
  国内免费   1篇
耳鼻咽喉   1篇
儿科学   7篇
妇产科学   43篇
基础医学   54篇
口腔科学   9篇
临床医学   67篇
内科学   284篇
皮肤病学   26篇
神经病学   124篇
特种医学   22篇
外科学   93篇
综合类   4篇
预防医学   29篇
眼科学   2篇
药学   47篇
肿瘤学   59篇
  2023年   6篇
  2022年   7篇
  2021年   16篇
  2020年   7篇
  2019年   20篇
  2018年   26篇
  2017年   19篇
  2016年   26篇
  2015年   18篇
  2014年   39篇
  2013年   52篇
  2012年   53篇
  2011年   74篇
  2010年   32篇
  2009年   30篇
  2008年   53篇
  2007年   56篇
  2006年   53篇
  2005年   46篇
  2004年   32篇
  2003年   28篇
  2002年   27篇
  2001年   20篇
  2000年   22篇
  1999年   22篇
  1998年   11篇
  1997年   8篇
  1996年   4篇
  1995年   4篇
  1994年   6篇
  1993年   2篇
  1992年   4篇
  1991年   10篇
  1990年   3篇
  1989年   6篇
  1988年   3篇
  1986年   3篇
  1985年   4篇
  1983年   2篇
  1982年   2篇
  1981年   1篇
  1980年   1篇
  1979年   3篇
  1978年   3篇
  1974年   1篇
  1973年   4篇
  1971年   2篇
排序方式: 共有871条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
Negative affective stimuli elicit behavioral and neural responses which vary on a continuum from adaptive to maladaptive, yet are typically investigated in a dichotomous manner (healthy controls vs. psychiatric diagnoses). This practice may limit our ability to fully capture variance from acute responses to negative affective stimuli to psychopathology at the extreme end. To address this, we conducted a functional magnetic resonance imaging study to examine the neural responses to negative valence/high arousal and neutral valence/low arousal images as a function of dysphoric mood and sex across individuals (n = 99) who represented traditional categories of healthy controls, major depressive disorder, bipolar psychosis, and schizophrenia. Observation of negative (vs. neutral) stimuli elicited blood oxygen‐level dependent responses in the following circuitry: periaqueductal gray, hypothalamus (HYPO), amygdala (AMYG), hippocampus (HIPP), orbitofrontal cortex (OFC), medial prefrontal cortex (mPFC), and greater connectivity between AMYG and mPFC. Across all subjects, severity of dysphoric mood was associated with hyperactivity of HYPO, and, among females, right (R) AMYG. Females also demonstrated inverse relationships between severity of dysphoric mood and connectivity between HYPO ‐ R OFC, R AMYG ‐ R OFC, and R AMYG ‐ R HIPP. Overall, our findings demonstrated sex‐dependent deficits in response to negative affective stimuli increasing as a function of dysphoric mood state. Females demonstrated greater inability to regulate arousal as mood became more dysphoric. These findings contribute to elucidating biosignatures associated with response to negative stimuli across disorders and suggest the importance of a sex‐dependent lens in determining these biosignatures. Hum Brain Mapp 37:3733–3744, 2016. © 2016 Wiley Periodicals, Inc .  相似文献   
75.
BACKGROUND: Left atrial systolic dysfunction, unexplained by altered loading conditions, has been reported in idiopathic dilated cardiomyopathy suggesting left atrial involvement in the myopathic process. MATERIALS AND METHODS: Seventeen patients with idiopathic dilated cardiomyopathy, 16 with ischemic dilated cardiomyopathy and 18 normal controls were studied with transthoracic echocardiography and cardiac catheterization. Transmitral diastolic flow was evaluated with pulsed Doppler. Left atrial volume (cm3/m2) at mitral valve opening (maximal, Vmax.), onset of atrial systole (P wave of the electrocardiogram, Vp), and mitral valve closure (minimal, Vmin. ) was determined with two-dimensional echocardiography using the biplane area-length method. The left atrial active emptying fraction (ACTEF = [Vp-Vmin.] x 100/Vp) served as an index of systolic function. RESULTS: The peak early diastolic transmitral flow velocity (cm/sec) was similar in the three groups (idiopathic: 60 +/- 16, ischemic: 58 +/- 20, control: 56 +/- 22; P = NS), whereas the late diastolic transmitral flow velocity was lower but not significantly different in idiopathic compared to ischemic cardiomyopathy, and in both was lower than control (26 +/- 12 vs. 34 +/- 13 vs. 44 +/- 14, respectively; P < 0.05). Vmax. and Vp were similar in idiopathic and ischemic cardiomyopathy and greater than control (44.6 +/- 13.6 vs. 48.2 +/- 18.3 vs. 26.9 +/- 6.2; P < 0.05, and 34.6 +/- 13.4 vs. 30.8 +/- 10.9 vs. 16.7 +/- 3.7, respectively; P < 0.05). ACTEF was lower in idiopathic than in ischemic cardiomyopathy and in the latter it was similar to control (18 +/- 10% vs. 32 +/- 10% vs. 36 +/- 10%, respectively; P < 0.05). Moreover, ACTEF was inversely related to left atrial tension at end-of atrial systole both in idiopathic and in ischemic cardiomyopathy (r2 = 0.52, P = 0.001 and r2 = 0.57, P = 0.0007, respectively). However, at any given level of left atrial tension at end of atrial systole, ACTEF was lower in idiopathic than ischemic cardiomyopathy. CONCLUSION: Left atrial systolic function is depressed in idiopathic and preserved in ischemic dilated cardiomyopathy despite similar left atrial loading conditions. This finding suggests left atrial myopathy in the former, and may be related to the differences in the response to medical treatment and clinical outcome observed between the two conditions.  相似文献   
76.
77.
The continuing education course on Developmental Neurotoxicity Testing (DNT) was designed to communicate current practices for DNT neuropathology, describe promising innovations in quantitative analysis and noninvasive imaging, and facilitate a discussion among experienced neuropathologists and regulatory scientists regarding suitable DNT practices. Conventional DNT neuropathology endpoints are qualitative histopathology and morphometric endpoints of particularly vulnerable sites (e.g., cerebral, cerebellar, or hippocampal thickness). Novel imaging and stereology measurements hold promise for automated analysis of factors that cannot be effectively examined in routinely processed specimens (e.g., cell numbers, fiber tract integrity). The panel recommended that dedicated DNT neuropathology data sets be acquired on a minimum of 8 sections (for qualitative assessment) or 3 sections (for quantitative linear and stereological analyses) using a small battery of stains to examine neurons and myelin. Where guidelines permit discretion, immersion fixation is acceptable for younger animals (postnatal day 22 or earlier), and peripheral nerves may be embedded in paraffin. Frequent concerns regarding DNT data sets include false-negative outcomes due to processing difficulties (e.g., lack of concordance among sections from different animals) and insensitive analytical endpoints (e.g., qualitative evaluation) as well as false-positive results arising from overinterpretation or misreading by inexperienced pathologists.  相似文献   
78.

Background

Redo fundoplication has acceptable outcomes in patients with failed previous fundoplications. However, a subset of patients require Roux-en-Y (RNY) reconstruction for symptom relief.

Aim

The aim of this study was to demonstrate safety and efficacy of RNY reconstruction for failed fundoplications.

Method

Retrospective review of data on patients who underwent short-limb RNY gastrojejunostomy (GJ) or esophagojejunostomy (EJ) between the years 2005 and 2007 was performed.

Results

Twenty-two patients underwent RNY reconstructions. Fourteen (64%) patients had one, six (27%) patients had two, and 2 (9%) patients had three previous anti-reflux procedures. RNY GJ was performed in 18 patients and EJ in four patients. Gastrectomy was performed in 13 of these patients. Seven patients (32%) had ten major or minor complications within the 30-day postoperative period, without any mortality observed. At a mean follow-up of 23 months, completed in 21 of these patients (95%), the average heartburn score was 0.38 (range, 0–2). The average regurgitation score was 0.23 (range, 0 to2) and the average dysphagia score was 0.7 (range, 0–2). The mean postoperative BMI was 25.4 compared to a preoperative BMI of 31.

Conclusion

RNY reconstruction with GJ or EJ for failed anti-reflux procedures is a safe, valid surgical option in difficult situations, where a redo fundoplication is either non-feasible or expected to fail. However, it is associated with higher morbidity.  相似文献   
79.
PURPOSE OF REVIEW: The present paper reviews the recent literature on the management of malignant large airway obstruction using tracheobronchial stenting and airway replacement by aortic allografts. RECENT FINDINGS: Airway stenting is a valuable adjunct to therapeutic bronchoscopy to relieve malignant airway obstruction. Over 80% of patients with obstructing lesions who were treated by airway stenting presented immediate symptom improvement in recent series. Stenting may also function as a bridge until further curative treatment can be used. Different stent models are available; their advantages and disadvantages depend on materials and constructions; clinical experience is larger with silicon-based models than with metallic stents. An alternative strategy for the management of nonresectable primary tracheal tumors aiming to replace the central airway with an allogenic aortic allograft has been proposed. Experimental studies showed that an aortic allograft produced a respiratory conduit that shared fundamental elements of the trachea and newly formed cartilage rings were observed. SUMMARY: Airway stenting provides efficient palliation of symptoms in patients with malignant central airway obstruction. Evidence-based studies are needed to identify patients who may have the greatest benefit from stenting. Tracheal replacement with allogenic aortic allografts is a novel technique which brings hope to the management of extensive tracheal lesions.  相似文献   
80.
In this study, we examined the role of the hippocampus in relational memory by comparing item recognition performance in amnesic patients with medial temporal lobe (MTL) damage and their matched controls. Specifically, we investigated the contribution of associative memory to item recognition using a cued recognition paradigm. Control subjects studied cue-target pairs once, whereas amnesic patients studied cue-target pairs six times. Following study, subjects made recognition judgments about targets that were presented either alone (no cue), with the originally presented cue (same cue), or with a cue that had been presented with a different target (recombined cue). Controls had higher recognition scores in the same cue than in the recombined cue condition, indicating that they benefited from the associative information provided by the same cue. By contrast, amnesic patients did not. This was true even for a subgroup of patients whose recognition performance in the no cue condition was matched to that of the controls. These data provide further support for the idea that the hippocampus plays a critical role in relational memory, even when associative information need not be retrieved intentionally.  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