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   3293篇
  免费   301篇
  国内免费   22篇
耳鼻咽喉   32篇
儿科学   71篇
妇产科学   53篇
基础医学   479篇
口腔科学   106篇
临床医学   412篇
内科学   638篇
皮肤病学   66篇
神经病学   268篇
特种医学   233篇
外国民族医学   1篇
外科学   363篇
综合类   84篇
一般理论   1篇
预防医学   296篇
眼科学   76篇
药学   227篇
中国医学   2篇
肿瘤学   208篇
  2022年   20篇
  2021年   43篇
  2020年   22篇
  2019年   45篇
  2018年   65篇
  2017年   47篇
  2016年   39篇
  2015年   78篇
  2014年   57篇
  2013年   99篇
  2012年   141篇
  2011年   120篇
  2010年   96篇
  2009年   127篇
  2008年   134篇
  2007年   109篇
  2006年   106篇
  2005年   112篇
  2004年   139篇
  2003年   103篇
  2002年   86篇
  2001年   95篇
  2000年   87篇
  1999年   96篇
  1998年   90篇
  1997年   95篇
  1996年   84篇
  1995年   78篇
  1994年   59篇
  1993年   56篇
  1992年   69篇
  1991年   78篇
  1990年   74篇
  1989年   82篇
  1988年   72篇
  1987年   62篇
  1986年   74篇
  1985年   57篇
  1984年   43篇
  1983年   49篇
  1982年   46篇
  1980年   29篇
  1979年   37篇
  1978年   29篇
  1976年   22篇
  1975年   28篇
  1973年   25篇
  1971年   18篇
  1969年   21篇
  1968年   19篇
排序方式: 共有3616条查询结果,搜索用时 281 毫秒
11.
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   

12.
13.
Primary dystonia is a disorder of movement for which no consistent pathophysiology has been identified; in the absence of evidence to the contrary, it is assumed to be cognitively benign. We have studied a clinically heterogeneous group of 14 patients with primary dystonia on a battery of neuropsychological tests. Despite well-preserved speed of information processing, language, spatial, memory and general intellectual skills relative to normal controls, we have identified a constellation of attentional-executive cognitive deficits on the Cambridge Neuropsychological Test Automated Battery (CANTAB). Specifically, patients demonstrated significant difficulties negotiating the extra-dimensional set-shifting phase of the IED task. The implications of these findings for the pathophysiology of primary dystonia are discussed. This is, to the best of our knowledge, the first report of a significant cognitive deficit in patients with primary dystonia.  相似文献   
14.
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   
15.
We report a patient with alcohol-induced necrotizing pancreatitis who developed a severe ileus followed by incarceration of a portion of the transverse colon within a ventral hernia. Laparotomy 9 days after the onset of symptoms revealed infarction of the transverse colon and infection of the pancreas. This is the first report of a case of acute pancreatitis that led to a strangulated ventral hernia of the colon. We believe that the enteric organisms that infected the pancreas originated in the incarcerated transverse colon.  相似文献   
16.
OBJECTIVES: We tested the hypothesis that mastoid volume buffers the rate of change in middle ear pressure caused by transmucosal, inert gas exchange. STUDY DESIGN: Twelve monkeys were randomly assigned to group 1 or group 2. Right ears of group 1 had sham surgery and of group 2 had obstruction of the mastoid antrum. Before and after surgery, the time constant for transmucosal N(2)O exchange was estimated from N(2)O breathing experiments. The hypothesis predicts that the postoperative time constant measured for right ears of group 2 but not group 1 is greater than that measured before surgery. RESULTS: Mastoid antrum block significantly decreased right middle ear volume but did not affect the time constant for transmucosal N(2)O exchange. CONCLUSION: A mastoid gas-reserve function is not supported by the experimental data. SIGNIFICANCE: These results for monkeys and the theory developed to explain the effect of mastoid volume on transmucosal inert gas exchange suggest that the results for previous experiments in humans interpreted as evidencing a mastoid gas-reserve function are consistent with alternative explanations.  相似文献   
17.
Cutaneous metastasis of vaginal carcinoma is extremely rare. So far, the total number of reported skin metastasis of vaginal carcinoma is only one. We present another case with an unusual manifestation of vagina carcinoma metastasis: skin metastasis presenting as a leg ulcer on the lower leg.  相似文献   
18.
19.
New York State’s Children and Youth Intensive Case Management (CYICM) was implemented in 1988 as one of several community-based initiatives for children with serious emotional disturbance (SED). Underlying this program is the goal of maintaining children with SED in the least restrictive environment appropriate to their needs. This paper presents CYICM child, family, and system outcomes over six years, describes program refinements, and explores continuing research efforts. Data are supportive of the positive outcomes associated with intensive case management for children with SED. Associated with enrollment in CYICM are a decrease in symptoms, improvement in functioning, and fewer hospitalizations in state-operated psychiatric centers, which translates into cost savings and a possible reduction in hospital beds.  相似文献   
20.
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