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   1291822篇
  免费   100988篇
  国内免费   2021篇
耳鼻咽喉   18563篇
儿科学   44755篇
妇产科学   35291篇
基础医学   184207篇
口腔科学   34120篇
临床医学   112698篇
内科学   261615篇
皮肤病学   28173篇
神经病学   101894篇
特种医学   51827篇
外国民族医学   661篇
外科学   198273篇
综合类   27337篇
现状与发展   1篇
一般理论   393篇
预防医学   96957篇
眼科学   28353篇
药学   95840篇
  2篇
中国医学   2431篇
肿瘤学   71440篇
  2018年   13366篇
  2017年   10155篇
  2016年   11124篇
  2015年   12630篇
  2014年   17543篇
  2013年   26878篇
  2012年   36887篇
  2011年   38990篇
  2010年   23311篇
  2009年   22319篇
  2008年   37618篇
  2007年   40306篇
  2006年   40562篇
  2005年   39486篇
  2004年   38583篇
  2003年   37413篇
  2002年   36758篇
  2001年   64194篇
  2000年   66689篇
  1999年   56608篇
  1998年   15367篇
  1997年   13955篇
  1996年   14376篇
  1995年   13643篇
  1994年   12920篇
  1993年   11927篇
  1992年   44703篇
  1991年   43592篇
  1990年   42375篇
  1989年   40231篇
  1988年   37042篇
  1987年   36383篇
  1986年   33742篇
  1985年   32417篇
  1984年   24276篇
  1983年   20399篇
  1982年   11899篇
  1981年   10868篇
  1980年   9653篇
  1979年   21459篇
  1978年   14904篇
  1977年   12602篇
  1976年   11762篇
  1975年   12681篇
  1974年   14731篇
  1973年   14170篇
  1972年   13001篇
  1971年   11776篇
  1970年   11085篇
  1969年   10063篇
排序方式: 共有10000条查询结果,搜索用时 875 毫秒
181.
182.
183.

Objective

Hypertonic saline (HTS) has potent immune and vascular effects. We assessed recipient pretreatment with HTS on allograft function in a porcine model of heart transplantation and hypothesized that HTS infusion would limit endothelial and left ventricular (LV) dysfunction following transplantation.

Methods

Heart transplants were performed after 6 hours of cold ischemic storage. Recipient pigs were randomized to treatment with or without HTS (7.5% NaCl) before cardiopulmonary bypass (CPB). Using a myograft apparatus, coronary artery endothelial-dependent (Edep) and -independent (Eind) relaxation was assessed. LV performance was determined using pressure-volume loop analysis. Pulmonary interleukin (IL)-2, IL-6, and tumor necrosis factor (TNF)-α expression was measured.

Results

Weaning from CPB and LV performance after transplantation were improved in HTS-treated animals. Successful weaning from CPB was greater in the HTS-treated hearts (8 of 8 vs 2 of 8; P < .05). Mean LV functional recovery was improved in the HTS-treated animals, as assessed by preload recruitable stroke work (65 ± 10% vs 27 ± 10%; P < .001) and end-systolic elastance (55 ± 7% vs 37 ± 4%; P < .001). Treatment with HTS resulted in improved Edep (mean maximum elastance [Emax], 56 ± 5% vs 37 ± 7%; P < .001) and Eind (mean Emax%, 77 ± 6% vs 52 ± 4%; P < .001) vasorelaxation compared with control. Pulmonary expression of IL-2, IL-6, and TNF-α increased following transplantation, whereas HTS therapy attenuated IL production (P < .001). Transplantation increased plasma TNF-α levels and LV TNF-α expression, whereas HTS prevented this up-regulation (P < .001).

Conclusions

Recipient HTS pretreatment preserves allograft vasomotor and LV function, and HTS therapy limits CPB-induced injury. HTS may be a novel recipient intervention to prevent graft dysfunction.  相似文献   
184.

Introduction

The fast track / ultra-fast-track protocols are techniques used to optimise the patient care process and a quick recovery after cardiac surgery. They are one of the mainstays of efficient practice. With their use, the length of hospital and intensive care unit (ICU) stays are reduced, with a direct impact on costs and the quality of the health service.

Objective

To compare the length of stay in the ICU, length of hospital stay, and post-operative mortality in ultra-fast-track extubated (uFTE) patients and those with conventional extubation (CE) after cardiac surgery.

Methods

Longitudinal, analytical, retrospective study was conducted, with the period between the time of surgery and discharge being included as the study period.

Results

A total of 396 patients older than 18 years who required cardiac surgery were included, of whom 207 patients had (uFTE) and 189 had CE. Although the groups were not comparable due to the statistical differences found, when performing the multivariate adjustment, uFTE maintained its statistical independence and was associated with lower cardiovascular morbidity, such as myocardial ischaemia (95% CI: 0.37-0.86; P = .01) and lower post-surgical vasopressor requirement (95% CI: 0.18-0.49; P < .01). No significant differences were found in the length of hospital stay, ICU stay, or post-operative mortality in the ICU.

Conclusion

Implementing the uFTE strategy, decreases cardiovascular morbidity and vasopressor requirement. The change to uFTE should be accompanied by changes in models and practices in patient recovery to standardised protocols. This study shows that uFTE did not reduce the length of ICU stay, hospital stay, or mortality.  相似文献   
185.
186.
Background & Aims: Impaired message-structure mapping results in deficits in both sentence production and comprehension in aphasia. Structural priming has been shown to facilitate syntactic production for persons with aphasia (PWA). However, it remains unknown if structural priming is also effective in sentence comprehension. We examined if PWA show preserved and lasting structural priming effects during interpretation of syntactically ambiguous sentences and if the priming effects occur independently of or in conjunction with lexical (verb) information.

Methods & Procedures: Eighteen PWA and 20 healthy older adults (HOA) completed a written sentence-picture matching task involving the interpretation of prepositional phrases (PP; the chef is poking the solider with an umbrella) that were ambiguous between high (verb modifier) and low attachment (object noun modifier). Only one interpretation was possible for prime sentences, while both interpretations were possible for target sentences. In Experiment 1, the target was presented immediately after the prime (0-lag). In Experiment 2, two filler items intervened between the prime and the target (2-lag). Within each experiment, the verb was repeated for half of the prime-target pairs, while different verbs were used for the other half. Participants’ off-line picture matching choices and response times were measured.

Results: After reading a prime sentence with a particular interpretation, HOA and PWA tended to interpret an ambiguous PP in a target sentence in the same way and with faster response times. Importantly, both groups continued to show this priming effect over a lag (Experiment 2), although the effect was not as reliable in response times. However, neither group showed lexical (verb-specific) boost on priming, deviating from robust lexical boost seen in the young adults of prior studies.

Conclusions: PWA demonstrate abstract (lexically-independent) structural priming in the absence of a lexically-specific boost. Abstract priming is preserved in aphasia, effectively facilitating not only immediate but also longer-lasting structure-message mapping during sentence comprehension.  相似文献   

187.
188.
189.
190.
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