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   535篇
  免费   32篇
  国内免费   7篇
耳鼻咽喉   2篇
儿科学   30篇
妇产科学   1篇
基础医学   47篇
口腔科学   33篇
临床医学   46篇
内科学   114篇
皮肤病学   17篇
神经病学   9篇
特种医学   99篇
外科学   59篇
综合类   24篇
预防医学   28篇
眼科学   4篇
药学   45篇
中国医学   1篇
肿瘤学   15篇
  2021年   15篇
  2020年   4篇
  2019年   1篇
  2018年   6篇
  2017年   3篇
  2016年   11篇
  2015年   10篇
  2014年   12篇
  2013年   27篇
  2012年   22篇
  2011年   8篇
  2010年   25篇
  2009年   26篇
  2008年   11篇
  2007年   10篇
  2006年   19篇
  2005年   11篇
  2004年   8篇
  2003年   13篇
  2002年   10篇
  2001年   10篇
  2000年   8篇
  1999年   19篇
  1998年   35篇
  1997年   25篇
  1996年   21篇
  1995年   13篇
  1994年   22篇
  1993年   23篇
  1992年   7篇
  1991年   6篇
  1990年   5篇
  1989年   13篇
  1988年   15篇
  1987年   9篇
  1986年   14篇
  1985年   7篇
  1984年   8篇
  1983年   6篇
  1982年   9篇
  1981年   12篇
  1980年   12篇
  1978年   4篇
  1977年   5篇
  1976年   9篇
  1975年   2篇
  1974年   1篇
  1957年   1篇
  1955年   1篇
排序方式: 共有574条查询结果,搜索用时 15 毫秒
31.
红豆杉提取物中紫杉醇的反相高效液相色谱法测定   总被引:2,自引:0,他引:2  
徐礼桑  刘爱茹 《药学学报》1989,24(7):552-555
本文报道应用反相高效液相色谱法测定红豆杉提取物中紫杉醇的含量,以倍他米松作内标,在填充以10μm LiChrosorb RP-18固定相的250×4mm不锈钢柱上以甲醇-水(30:10v/v)作流动相。228 nm处检测。本法简便、快速、准确,适用于微量样品的测定。  相似文献   
32.
The aim of this paper was to perform a systematic review of the pathogenesis of medication‐induced salivary gland dysfunction (MISGD). Review of the identified papers was based on the standards regarding the methodology for systematic reviews set forth by the World Workshop on Oral Medicine IV and the PRISMA statement. Eligible papers were assessed for both the degree and strength of relevance to the pathogenesis of MISGD as well as on the appropriateness of the study design and sample size. A total of 99 papers were retained for the final analysis. MISGD in human studies was generally reported as xerostomia (the sensation of oral dryness) without measurements of salivary secretion rate. Medications may act on the central nervous system (CNS) and/or at the neuroglandular junction on muscarinic, α‐and β‐adrenergic receptors and certain peptidergic receptors. The types of medications that were most commonly implicated for inducing salivary gland dysfunction were those acting on the nervous, cardiovascular, genitourinary, musculoskeletal, respiratory, and alimentary systems. Although many medications may affect the salivary flow rate and composition, most of the studies considered only xerostomia. Thus, further human studies are necessary to improve our understanding of the association between MISGD and the underlying pathophysiology.  相似文献   
33.
Human lymphocytes and Chinese hamster ovary (CHO) cells in culture were exposed for 12 1/2 hours to a magnetic resonance imaging apparatus with a 2.35-Tesla magnet and 100-MHz radio frequency emission. The cells were examined for cytogenetic damage manifested either as chromosome aberrations or sister chromatid exchanges (SCEs), which constitute very sensitive measures of genetic and cellular damage. In either unstimulated or stimulated human lymphocytes, as well as in exponentially growing CHO cells, no increase in either chromosome aberrations or SCEs was found as a result of exposure to these MR conditions. The data indicate that long-term exposure to MR imaging conditions far exceeding those to be found in the clinical situation does not cause cytogenetic damage.  相似文献   
34.
薄层扫描法测定熊胆引流物中胆汁酸含量   总被引:4,自引:0,他引:4  
熊胆向以贵重药材闻名,被称之为稀有药品,为开发熊胆资源,解决熊胆奇缺问题,我校解剖教研室已成功地完成了人工引流熊胆汁技术,可随时进行人工引流获取熊胆汁。为了确定胆汁的质量指标,了解其主要成分,我们进行了引流胆汁与天然熊胆的分析。文献报道,熊胆中主要含熊去氧胆酸(ursodesoxycholic acid,UDCA)、鹅去氧胆酸(cheno desoxycholic acid,CDCA)、胆酸(cholic acid,CA)、去氧胆酸(deoxycholic,acid DCA)等。  相似文献   
35.
L-Tryptophan (L-TP) has been used in migraine and other pain conditions. The mechanism underlying the analgesic effect is still partly undefined. In this study the effects of subchronic administration of L-5-hydroxy-tryptophan (L-5HTP) (with and without carbidopa) on plasma beta-endorphin (beta-EP) levels and subjective pain threshold and tolerance were investigated in seven healthy volunteers. To measure also an objective indicator for pain, the nociceptive flexion reflex threshold was studied. L-5HTP treatment with and without carbidopa administration increased beta-EP levels significantly (p less than 0.05). L-5HTP plus carbidopa induced an increase in beta-EP significantly (p less than 0.05) higher than that after L-5HTP alone. Neither subjective pain threshold and tolerance nor RIII threshold was modified by either treatment. Our data seem to point to the existence of a complex linkage between plasma opioid levels and pain perception.  相似文献   
36.
The diagnostic value of biphasic radiographic examination of the stomach and duodenum was compared with that of fiberoptic endoscopy in a prospective, blinded study of 385 patients with dyspepsia. This investigation was directed at gastric malignancies and peptic ulcers. Methodologically there is no absolute standard for a study of this kind because histologic examination is useful for detection of cancer but inadequate for ulcers. As an alternative, kappa indexes and the sensitivity and specificity, as derived by Hui and Walter, were calculated and compared. For the detection of gastric carcinoma, radiographic and endoscopic findings had almost perfect agreement beyond chance. For gastric ulcers, radiography and endoscopy had substantial agreement, which became perfect if small ulcers (less than 5 mm) were excluded. For duodenal ulcers, radiography had a lower sensitivity than endoscopy; this disagreement disappeared if small ulcers were excluded. Both methods have equal merit; choice of the initial diagnostic procedure will therefore depend on cost, discomfort to the patient, and risk of complications.  相似文献   
37.
38.
We have previously shown that eating disorders are a compulsive behaviour disease, characterized by frequent recall of anorexic thoughts. Evidence suggests that memory is a neocortical neuronal network, excitation of which involves the hippocampus, with recall occurring by re-excitement of the same specific network. Excitement of the hippocampus by glutamate-NMDA receptors, leading to long-term potentiation (LTP), can be blocked by ketamine. Continuous block of LTP prevents new memory formation but does not affect previous memories. Opioid antagonists prevent loss of consciousness with ketamine but do not prevent the block of LTP. We used infusions of 20 mg per hour ketamine for 10 h with 20 mg twice daily nalmefene as opioid antagonist to treat 15 patients with a long history of eating disorder, all of whom were chronic and resistant to several other forms of treatment. Nine (responders) showed prolonged remission when treated with two to nine ketamine infusions at intervals of 5 days to 3 weeks. Clinical response was associated with a significant decrease in Compulsion score: before ketamine, mean +/- SE was 44.0 +/- 2.5; after ketamine, 27.0 +/- 3.5 (t test, p = 0.0016). In six patients (non-responders) the score was: before ketamine, 42.8 +/- 3.7; after ketamine, 44.8 +/- 3.1. There was no significant response to at least five ketamine treatments, perhaps because the compulsive drive was re-established too soon after the infusion, or because the dose of opioid antagonist, nalmefene, was too low. ARDEF>  相似文献   
39.
In order to describe the British experience of Wegener's granuiomatosisHospital Activity Analysis was used to collect cases diagnosedin England, Wales and Scotland between 1975 and 1985. Wherepossible clinical details, histological material and chest radiographswere obtained. Two hundred and sixty five patients were consideredto have Wegener's granuiomatosis. In 109 a single pathologistconfirmed the diagnosis by finding both granulomas and vasculitisin biopsy material. The diagnosis was made on clinical groundsor clinical grounds together with histological diagnosis inthe local hospital in 156 patients. Wegener's granuiomatosiswas confined to the lung or upper respiratory tract in 22 percent of patients and renal disease occurred in 58 per cent.Laboratory tests showed a pattern of mild anaemia, polymorphleucocytosis, eosinophilia and an elevated ESR and hypergammaglobulinaemia,with no specific pattern of changes. Histological confirmation was most frequently obtained by examinationof nasal biopsy specimens, but multiple biopsies were oftenrequired. Renal biopsies showed focal proliferative glomerulonephritisbut granulomatous glomerulonephritis was uncommon. Of availablechest radiographs 61 per cent were abnormal, large opacitiesbeing most common. Small irregular opacities were found lessoften and other abnormalities were uncommon. Treatment varied widely and 10 per cent of patients receivedno drug therapy. This large series illustrates that even withoutspecific treatment, patients with Wegener's granuiomatosis cansurvive for several years and with modern treatment survivalfor more than a decade is possible. Conclusions about the effectivenessof the various therapies cannot be drawn from this restrospectivestudy. Renal failure and disseminated vasculities were the commonestcauses of death; death was considered to result from complicationsof treatment with cytotoxic drugs or prednisolone in 6 per centof patients.  相似文献   
40.
To determine the cost of expanding blood product operations, the concept of marginal cost must be used. This article reports the development and implementation of a method of costing increases in collecting plasma using apheresis operations. The model takes into account the fact that certain resource inputs--notably, direct labor and machines--increase in discrete steps rather than in a continuous manner. To address this fact, a stepwise cost analysis function was developed, which related operating costs to the volume of apheresis collections. This function was used to predict the marginal costs of potential increases in the supply of plasma at a blood center in Canada. Differences were noted in the cost of plasma in Canada and the United States, much of which could be attributed to different standards regarding the volume of plasma per collection and to differences in pricing materials.  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