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   2286802篇
  免费   167227篇
  国内免费   3355篇
耳鼻咽喉   31601篇
儿科学   75597篇
妇产科学   65743篇
基础医学   336476篇
口腔科学   64489篇
临床医学   205117篇
内科学   443828篇
皮肤病学   48467篇
神经病学   181377篇
特种医学   87156篇
外国民族医学   602篇
外科学   338891篇
综合类   48158篇
现状与发展   4篇
一般理论   823篇
预防医学   179954篇
眼科学   52253篇
药学   171290篇
  7篇
中国医学   4091篇
肿瘤学   121460篇
  2018年   22767篇
  2016年   19167篇
  2015年   22253篇
  2014年   30742篇
  2013年   46969篇
  2012年   64202篇
  2011年   68623篇
  2010年   40128篇
  2009年   38299篇
  2008年   65548篇
  2007年   70559篇
  2006年   70890篇
  2005年   69482篇
  2004年   66879篇
  2003年   64292篇
  2002年   63012篇
  2001年   100034篇
  2000年   102473篇
  1999年   86844篇
  1998年   24988篇
  1997年   22428篇
  1996年   22884篇
  1995年   21714篇
  1994年   20462篇
  1993年   18965篇
  1992年   69969篇
  1991年   69012篇
  1990年   67727篇
  1989年   65635篇
  1988年   61144篇
  1987年   60037篇
  1986年   57273篇
  1985年   54518篇
  1984年   41094篇
  1983年   35788篇
  1982年   21433篇
  1981年   19292篇
  1979年   39436篇
  1978年   28318篇
  1977年   24059篇
  1976年   22552篇
  1975年   24586篇
  1974年   29431篇
  1973年   28656篇
  1972年   27204篇
  1971年   25358篇
  1970年   23759篇
  1969年   22707篇
  1968年   21278篇
  1967年   18951篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Pharmaceutical Chemistry Journal - An HPLC-MS method for simultaneous quantitative determination of a novel gestagenic pharmaceutical and two of its metabolites in rat and rabbit blood sera was...  相似文献   
12.
To determine percent of patients without malignancy and ≤ 40 years of age with high cumulative radiation doses through recurrent CT exams and assess imaging appropriateness. From the cohort of patients who received cumulative effective dose (CED) of ≥ 100 mSv over a 5-year period, a sub-set was identified with non-malignant disease. The top 50 clinical indications leading to multiple CTs were determined. Clinical decision support (CDS) system scores were analyzed using a widely adopted standard of 1–3 (red) as “not usually appropriate,” 4–6 (yellow) “may or may not be appropriate,” and 7–9 (green) “usually appropriate.” Clinicians reviewed patient records to assess compliance with appropriate use criteria (AUC). 9.6% of patients in our series were with non-malignant conditions and 1.4% with age ≤ 40 years. CDS scores (rounded) were 2% red, 38% yellow, 27% green, and 33% unscored CTs. Clinical society guidelines for CT exams, wherever available, were followed in 87.5 to 100% of cases. AUCs were not available for several clinical indications as also referral guidelines for serial CT imaging. More than half of CT exams were unrelated to follow-up of a primary chronic disease. We are faced with a situation wherein patients in age ≤ 40 years require or are thought to require many CT exams over the course of a few years but the radiation risk creates concern. There is a fair number of conditions for which AUC are not available. Suggested solutions include development of CT scanners with lesser radiation dose and further development of appropriateness criteria.  相似文献   
13.
14.
Bulletin of Experimental Biology and Medicine - Ammonium, an end-product of catabolism, in low doses can promote adaptation of metabolic pathways in erythrocytes under conditions of extreme...  相似文献   
15.

Objectives

Expedient extubation after cardiac surgery has been associated with improved outcomes, leading to postoperative extubation frequently during overnight hours. However, recent evidence in a mixed medical-surgical intensive care unit population demonstrated worse outcomes with overnight extubation. This study investigated the impact of overnight extubation in a statewide, multicenter Society of Thoracic Surgeons database.

Methods

Records from 39,812 patients undergoing coronary artery bypass grafting or valve operations (2008-2016) and extubated within 24 hours were stratified according to extubation time between 06:00 and 18:00 (day) or between 18:00 and 6:00 (overnight). Outcomes including reintubation, mortality, and composite morbidity-mortality were evaluated using hierarchical regression models adjusted for Society of Thoracic Surgeons predictive risk scores. To further analyze extubation during the night, a subanalysis stratified patients into 3 groups: 06:00 to 18:00, 18:00 to 24:00, and 24:00 to 06:00.

Results

A total of 20,758 patients were extubated overnight (52.1%) and were slightly older (median age 66 vs 65 years, P < .001) with a longer duration of ventilation (4 vs 7 hours, P < .001). Day and overnight extubation were associated with equivalent operative mortality (1.7% vs 1.7%, P = .880), reintubation (3.7% vs 3.4%, P = .141), and composite morbidity-mortality (8.2% vs 8.0%, P = .314). After risk adjustment, overnight extubation was not associated with any difference in reintubation, mortality, or composite morbidity-mortality. On subanalysis, those extubated between 24:00 and 06:00 exhibited increased composite morbidity-mortality (odds ratio, 1.18; P = .001) but no difference in reintubation or mortality.

Conclusions

Extubation overnight was not associated with increased mortality or reintubation. These results suggest that in the appropriate clinical setting, it is safe to routinely extubate cardiac surgery patients overnight.  相似文献   
16.
17.
18.
19.
20.
Sinus venosus atrial septal defect (SV‐ASD) usually coexists with partial anomalous pulmonary vein connection (PAPVC). It is a difficult diagnosis in transthoracic echocardiography (TTE) due to eccentric position of defects. We present a rare case of atypical anatomical variation in PAPVC, which was never described before. Two right pulmonary veins drained into superior vena cava, which overrode SV‐ASD and interatrial septum, a third pulmonary vein into the right atrium. Complete diagnosis could not be set after TTE, nor transesophageal echocardiography, whereas angio‐CT was finally conclusive. This diagnostic approach allowed the surgical planning.  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