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   15307篇
  免费   1424篇
  国内免费   68篇
耳鼻咽喉   229篇
儿科学   542篇
妇产科学   360篇
基础医学   1910篇
口腔科学   414篇
临床医学   1107篇
内科学   3408篇
皮肤病学   594篇
神经病学   904篇
特种医学   581篇
外国民族医学   6篇
外科学   2655篇
综合类   147篇
一般理论   2篇
预防医学   1128篇
眼科学   408篇
药学   1211篇
中国医学   90篇
肿瘤学   1103篇
  2023年   118篇
  2022年   398篇
  2021年   587篇
  2020年   401篇
  2019年   655篇
  2018年   831篇
  2017年   567篇
  2016年   605篇
  2015年   534篇
  2014年   747篇
  2013年   1019篇
  2012年   1162篇
  2011年   1268篇
  2010年   819篇
  2009年   747篇
  2008年   820篇
  2007年   801篇
  2006年   753篇
  2005年   612篇
  2004年   572篇
  2003年   391篇
  2002年   380篇
  2001年   294篇
  2000年   315篇
  1999年   230篇
  1998年   89篇
  1997年   71篇
  1996年   65篇
  1995年   42篇
  1994年   39篇
  1993年   35篇
  1992年   34篇
  1991年   35篇
  1990年   32篇
  1989年   28篇
  1988年   31篇
  1987年   25篇
  1985年   27篇
  1984年   82篇
  1983年   68篇
  1982年   42篇
  1981年   27篇
  1980年   41篇
  1979年   49篇
  1978年   44篇
  1977年   36篇
  1976年   35篇
  1975年   38篇
  1974年   20篇
  1973年   17篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Extubation failure in the elderly   总被引:2,自引:0,他引:2  
To determine the causes, risk factors and complications of planned extubation failure of critically ill elderly patients, we conducted a prospective study of 175 consecutive patients (> or = 70 years old) admitted with respiratory failure. Thirty-six (21%) failed extubation within 72 h after planned extubation. Compared to a younger age group (< 70 years old) matched for severity of illness, inability to handle secretions (20%) was the most common reason of airway causes leading to extubation failure in the elderly while upper airway obstruction (22%) was the predominant cause in the control group. As for nonairway causes, COPD related hypercapnic respiratory failure accounted for the majority of cases in both groups. After adjusting for severity of illness, elderly patients who required reintubation had a higher risk of developing nosocomial pneumonia. The presence of underlying pulmonary disease (odds ratio (OR), 2.9; 95% confidence interval (CI) 1.2-6.9), length of intubation > 4 days (OR, 4.3; 95% CI 1.8-10.2), and albumin levels < 2.5 g/dl (OR, 2.7; 95% CI 1.2-6.7) were independently associated with extubation failure in the old. Objective measurements of cough strength and secretion volume are needed to reduce the morbidity of elderly patients at risk for extubation failure.  相似文献   
993.
BACKGROUND: Bullous pemphigoid has developed in association with different types of malignant diseases, including a few cases of B-cell lymphoproliferative disorders. However, the paraneoplastic significance of this association is still controversial. OBSERVATIONS: We describe a 39-year-old patient who presented with a bullous eruption and generalized lymphadenopathy. The results of histologic, immunofluorescence, and antigenic studies confirmed the diagnosis of bullous pemphigoid. The histopathologic and immunophenotypic features of a lymph node biopsy specimen were consistent with mantle cell lymphoma. There was total resolution of the mucocutaneous lesions when mantle cell lymphoma went into remission. CONCLUSION: The age of the patient and the concomitant appearance and simultaneous remission of both diseases strongly suggest that bullous pemphigoid was a paraneoplastic phenomenon in the present case.  相似文献   
994.
The authors report three cases of non-tuberculous epidural abscess. Presenting symptoms included lumbar back pain, muscle spasms, soft tIssue swelling, and neurological deficits in all three cases. MR imaging was helpful for diagnosis and showed involvement of perivertebral soft tissues and an epidural abscess of variable size. There was no significant involvement of intervertebral disks or vertebrae. Diagnosis was confirmed by bacteriologic exam. Clinical outcome was favourable with antibiotic treatment.  相似文献   
995.
996.
Plasma neuropeptide Y-like immunoreactivity (NPY-LI) and platelet cyclic AMP (cAMP) activity were determined in 13 women with bipolar disorder stabilized on lithium (Li) and 12 matched healthy controls. No differences in plasma NPY-LI were found between the two groups. In euthymic Li-treated bipolar patients, there was an inverse correlation between plasma NPY-LI levels and intracellular cAMP in prostaglandin E1-stimulated platelets. A positive correlation was found between plasma NPY-LI levels and age in both the patient and the control group. Our findings support earlier findings that NPY is capable of inhibiting adenylyl cyclase and that aging is a physiological factor in regulating NPY-LI levels.  相似文献   
997.
998.
Mammalian spinal motoneurons are cholinergic neurons that have long been suspected to use also glutamate as a neurotransmitter. We report that VGLUT1 and VGLUT2, two subtypes of vesicular glutamate transporters, are expressed in rat spinal motoneurons. Both proteins are present in somato-dendritic compartments as well as in axon terminals in primary cultures of immunopurified motoneurons and sections of spinal cord from adult rat. However, VGLUT1 and VGLUT2 are not found at neuromuscular junctions of skeletal muscles. After intracellular injection of biocytin in motoneurons, VGLUT2 is observed in anterogradely labelled terminals contacting Renshaw inhibitory interneurons. These VGLUT2- and VGLUT1-positive terminals do not express VAChT, the vesicular acetylcholine transporter. Overall, our study establishes for the first time that (i) mammalian spinal motoneurons express vesicular glutamate transporters, (ii) these motoneurons have the potential to release glutamate (in addition to acetylcholine) at terminals contacting Renshaw cells, and finally (iii) the VGLUTs are not present at neuromuscular synapses of skeletal muscles.  相似文献   
999.
PURPOSE: Mydriasert is an insoluble ophthalmic insert, gradually releasing two well-known active ingredients: phenylephrine and tropicamide. It is indicated in presurgical mydriasis. The purpose was to evaluate its efficacy in obtaining mydriasis required for fluorescein angiography. MATERIAL AND METHODS: The ability of Mydriasert to provide mydriasis (defined by a pupillary diameter of at least 7 mm) compatible with a bilateral angiographic examination in optimal conditions was evaluated by a comparative, randomised versus active treatment (eye drops) open trial in 72 patients. RESULTS: All the patients obtained a stable mydriasis allowing angiography. In the Mydriasert group, mydriasis preparation required a mean of 10 min more (Student t test: p<0.001); however, near eyesight recovery was 15 min shorter on average (log-rank test<0.01%) and amounts of active ingredients administered to provide mydriasis were 5-10 times higher in the eye drops reference group. Cardiovascular parameters remained in the normal range in both groups. Three patients of the Mydriasert group presented one ocular symptom of local intolerance, which disappeared in 15 min (exact Fisher test not significant between the treatment groups, p=0.2394). No superficial punctate keratitis was detected during the trial. CONCLUSION: The treatment by Mydriasert can prepare preangiographic mydriasis as well as the reference treatment. The time required for mydriasis is slightly longer. Near eyesight recovery, faster with Mydriasert, could provide an improvement in patient safety and comfort at the end of the ophthalmologic visit.  相似文献   
1000.
OBJECTIVE: The aim of this study was to determine the risk factors for postoperative infection after craniotomy, a threat for the vital prognosis, in order to define specific prevention measures. METHOD AND PATIENTS: An open prospective study was made on all adult patients undergoing craniotomy and followed 30 days postoperatively. The infections were defined according to CDCA criteria. The parameters studied were: age, sex, ASA and Glasgow scores, neurosurgical history, the type, the moment and the surface of shaving, antibioprophylaxis, and the type and duration of surgery as well as its emergency level. RESULTS: One hundred and seventy patients were included. Thirty presented with an infection (17.6%), nine with a skull infection, 13 with meningitis, three with empyema, and two with osteitis. The risk factors identified thanks to a univariate analysis were the emergency level of surgery (P < 0.01), duration of surgery >200 min, and duration of stay in ICU >72 h (P < 0.02).  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