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   1778篇
  免费   120篇
  国内免费   8篇
耳鼻咽喉   17篇
儿科学   51篇
妇产科学   43篇
基础医学   180篇
口腔科学   15篇
临床医学   112篇
内科学   501篇
皮肤病学   17篇
神经病学   130篇
特种医学   59篇
外科学   485篇
综合类   9篇
一般理论   3篇
预防医学   69篇
眼科学   34篇
药学   44篇
中国医学   6篇
肿瘤学   131篇
  2023年   5篇
  2022年   6篇
  2021年   44篇
  2020年   13篇
  2019年   30篇
  2018年   42篇
  2017年   42篇
  2016年   21篇
  2015年   33篇
  2014年   53篇
  2013年   67篇
  2012年   106篇
  2011年   116篇
  2010年   69篇
  2009年   71篇
  2008年   87篇
  2007年   137篇
  2006年   108篇
  2005年   115篇
  2004年   117篇
  2003年   102篇
  2002年   83篇
  2001年   53篇
  2000年   36篇
  1999年   24篇
  1998年   15篇
  1997年   23篇
  1996年   10篇
  1995年   12篇
  1994年   7篇
  1993年   8篇
  1992年   19篇
  1991年   19篇
  1990年   21篇
  1989年   20篇
  1988年   15篇
  1987年   21篇
  1986年   20篇
  1985年   24篇
  1984年   18篇
  1983年   9篇
  1982年   7篇
  1981年   5篇
  1980年   5篇
  1978年   5篇
  1977年   4篇
  1973年   3篇
  1971年   4篇
  1970年   4篇
  1967年   3篇
排序方式: 共有1906条查询结果,搜索用时 296 毫秒
1.
BACKGROUND: We hypothesized that the incidence of hypotension during total knee replacement (TKR) surgery is lower in patients given combined spinal-epidural (CSE) anesthesia vs those receiving epidural anesthesia alone. METHODS: In a prospective study, 80 American Society of Anesthesiologists I-II patients (aged 40-80 yr), undergoing elective TKR surgery were randomly assigned to either CSE anesthesia (CSE, n = 40) or epidural anesthesia alone (Epidural, n = 40). Hemodynamic measurements included oscillometric mean arterial blood pressure (MAP), heart rate (HR), and cardiac index (CI) as determined by thoracic bioimpedance; systemic vascular resistance (SVR) was calculated. Our primary endpoint (outcome) was the number of hypotension episodes (defined as MAP < 70 mmHg). RESULTS: Using univariate analysis, we found no differences between the groups in regards to MAP, HR, CI, or SVR during the perioperative period. The incidence of hypotension was similar in both groups (two patients in each group), as was the incidence of bradycardia (12 patients in CSE, 7 in Epidural; P = 0.2). There were no differences between groups in other hemodynamic measurements including CI and calculated SVR. Analgesia supplementation with fentanyl was more frequently required in the Epidural group (20 vs 6 patients - P = 0.03). CONCLUSION: Combined spinal-epidural anesthesia and epidural anesthesia alone during TKR surgery are associated with the same incidence of hypotension with statistically and clinically similar hemodynamic responses.  相似文献   
2.
3.
4.
5.
Chondroid syringoma of the vulva is an extremely rare tumor. Of the previously reported cases, only one was clinically malignant. The authors describe a case of chondroid syringoma of the right labium majus from which arose a papillary adenocarcinoma. A right inguinal lymph node was replaced with metastatic adenocarcinoma.  相似文献   
6.
Background. Hypoxia and warm ischemia produce severe injury to cardiac grafts harvested from non-heart-beating donors. To potentially improve recovery of such grafts, we studied the effects of intravenous phenylephrine preconditioning.

Methods. Thirty-seven blood-perfused rabbit hearts were studied. Three groups of non-heart-beating donors underwent intravenous treatment with phenylephrine at 12.5 (n = 8), 25 (n = 7), or 50 μg/kg (n = 7) before initiation of apnea. Non-heart-beating controls (n = 8) received saline vehicle. Hypoxic cardiac arrest occurred after 6 to 12 minutes of apnea, followed by 20 minutes of warm in vivo ischemia. A 45-minute period of ex vivo reperfusion ensued. Nonischemic controls (n = 7) were perfused without antecedent hypoxia or ischemia.

Results. Phenylephrine 25 μg/kg significantly delayed the onset of hypoxic cardiac arrest compared with saline controls (9.6 ± 0.5 versus 7.7 ± 0.4 minutes; p = 0.00001), yet improved recovery of left ventricular developed pressure compared with saline controls (57.1 ± 5.3 versus 41.0 ± 3.4 mm Hg; p = 0.04). Phenylephrine 25 μg/kg also yielded a trend toward less myocardial edema than saline vehicle (p = 0.09).

Conclusions. Functional recovery of nonbeating cardiac grafts is improved by preconditioning. We provide evidence that the myocardium can be preconditioned with phenylephrine against hypoxic cardiac arrest.  相似文献   

7.
8.
Background. Hypoxia and warm ischemia produce severe injury to cardiac grafts harvested from non–heart-beating donors. To potentially improve recovery of such grafts, we studied the effects of intravenous phenylephrine preconditioning.Methods. Thirty-seven blood-perfused rabbit hearts were studied. Three groups of non–heart-beating donors underwent intravenous treatment with phenylephrine at 12.5 (n = 8), 25 (n = 7), or 50 μg/kg (n = 7) before initiation of apnea. Non–heart-beating controls (n = 8) received saline vehicle. Hypoxic cardiac arrest occurred after 6 to 12 minutes of apnea, followed by 20 minutes of warm in vivo ischemia. A 45-minute period of ex vivo reperfusion ensued. Nonischemic controls (n = 7) were perfused without antecedent hypoxia or ischemia.Results. Phenylephrine 25 μg/kg significantly delayed the onset of hypoxic cardiac arrest compared with saline controls (9.6 ± 0.5 versus 7.7 ± 0.4 minutes; p = 0.00001), yet improved recovery of left ventricular developed pressure compared with saline controls (57.1 ± 5.3 versus 41.0 ± 3.4 mm Hg; p = 0.04). Phenylephrine 25 μg/kg also yielded a trend toward less myocardial edema than saline vehicle (p = 0.09).Conclusions. Functional recovery of nonbeating cardiac grafts is improved by preconditioning. We provide evidence that the myocardium can be preconditioned with phenylephrine against hypoxic cardiac arrest.(Ann Thorac Surg 1997;63:1664–8)  相似文献   
9.
Zusammenfassung Die Sedimentationsraten der kompletten löslichen Hämagglutinine der Adenoviren wurden bei 16 Prototypen der Untergruppe II im Saccharose-Gradienten bestimmt. Die Werte waren für alle Viren ähnlich (65±10S). Dies bedeutet, daß die strukturellen Komponenten ebenfalls identisch sein dürften, also Dodecon (1).
Dodecon, the soluble hemagglutinin present in all adenovirus types of subgroup II
Summary The sedimentation rate of the soluble complete hemagglutinins of 16 prototype adenoviruses of subgroup II were determined by means of sucrose gradient centrifugation. The rates were similar for all types (65±10S), thus indicating that the structural components may also be identicali.e. dodecon (1).


Durchgeführt mit Unterstützung der Deutschen Forschungsgemeinschaft.  相似文献   
10.
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