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   8216篇
  免费   679篇
  国内免费   8篇
耳鼻咽喉   112篇
儿科学   304篇
妇产科学   320篇
基础医学   1051篇
口腔科学   257篇
临床医学   826篇
内科学   1480篇
皮肤病学   260篇
神经病学   725篇
特种医学   309篇
外科学   1102篇
综合类   224篇
一般理论   7篇
预防医学   754篇
眼科学   66篇
药学   548篇
中国医学   13篇
肿瘤学   545篇
  2022年   55篇
  2021年   116篇
  2020年   62篇
  2019年   102篇
  2018年   121篇
  2017年   90篇
  2016年   89篇
  2015年   134篇
  2014年   178篇
  2013年   284篇
  2012年   348篇
  2011年   357篇
  2010年   204篇
  2009年   178篇
  2008年   319篇
  2007年   347篇
  2006年   319篇
  2005年   337篇
  2004年   324篇
  2003年   333篇
  2002年   300篇
  2001年   282篇
  2000年   298篇
  1999年   244篇
  1998年   83篇
  1997年   73篇
  1996年   79篇
  1995年   75篇
  1994年   73篇
  1992年   188篇
  1991年   210篇
  1990年   199篇
  1989年   170篇
  1988年   173篇
  1987年   198篇
  1986年   188篇
  1985年   162篇
  1984年   144篇
  1983年   111篇
  1982年   76篇
  1981年   78篇
  1980年   66篇
  1979年   105篇
  1978年   77篇
  1977年   59篇
  1976年   61篇
  1974年   78篇
  1973年   91篇
  1972年   74篇
  1970年   78篇
排序方式: 共有8903条查询结果,搜索用时 15 毫秒
11.
Sett  P. K.  Crockard  H. A.  Powell  M.  Lightman  S.  Jacobs  H. 《Acta neurochirurgica》1990,102(1-2):69-72
Summary Two cases of meningiomas, which are considered to have been caused by the preceding irradiation, are reported. In both cases, the cytokinetic study of the tumour using bromodeoxyuridine (BrdU) was performed. The percent of the tumour cells in the S phase of the cell cycle was less than 1% in both cases. The low labelling indices might suggest a relatively slow growing potential of these tumours, though the radiation-induced meningiomas were reported as being rapidly growing and malignant.  相似文献   
12.
Broviac catheters are commonly used to provide parenteral nutrition and access for infusion of blood products and drugs to pediatric patients. Sepsis is the most common serious complication of continued catheter use. Although removal of the catheter is generally recommended when it becomes contaminated, it may not be feasible to do so without compromising patient care. We evaluated the management of catheter-related infections in pediatric patients with and without removal of catheter. Seventy-seven episodes of catheter sepsis were evaluated in 61 pediatric patients; 24 were neonates and 37 were older children. The catheters were used for multiple purposes in 75% of cases. The most common microorganisms isolated were Staphylococcus epidermidis in 26%, Klebsiella pneumoniae in 9%, and Streptococcus viridans in 8% of cases; other pathogens included group D Enterococcus, Staphylococcus aureus, and Escherichia coli. Pseudomonas aeruginosa was isolated in four older children. Thirty-five patients were treated with antibiotics without catheter removal. Thirty patients received appropriate antibiotic therapy based on the susceptibility data. Twenty-six of these 30 patients responded within 5 days of therapy whereas the others required 15-39 days of treatment. Lack of response was mainly associated with the presence of abscess, immunocompromised status, and organisms P. aeruginosa and Candida albicans. Based on the sensitivity and minimum inhibitory concentration data, a combined regimen of gentamicin and vancomycin would be an effective initial therapy. These findings suggest that (1) catheter sepsis can be managed with appropriate antibiotics, and (2) when continued use of Broviac catheter is desired, a trial of antibiotic therapy should be attempted before catheter removal.  相似文献   
13.
Study Objective . To compare the frequency, severity, and time course of venous irritation after administration of a single intravenous dose of phenytoin with an equimolar dose of fosphenytoin, a water-soluble phenytoin prodrug. Design . Randomized, double-blind, two-period, crossover study. Setting . University hospital clinical research unit. Patients . Twelve healthy volunteers within 15% of ideal body weight and with no clinically significant abnormalities on physical examination, medical history, or laboratory assessment. Interventions . Volunteers randomly received a 30-minute infusion of phenytoin sodium 250 mg (250 mg/5 ml) or an equimolar dose of fosphenytoin 375 mg (375 mg/5 ml). Subjects returned for the crossover treatment 14–21 days later. Measurements and Main Results . Subjects assessed venous irritation (pain, burning, itching), and investigators evaluated phlebitis (erythema, swelling, tenderness), induration, exudation, and cording. Phenytoin was associated with a significantly higher degree of pain at the infusion site in all subjects and a significant degree of phlebitis in eight subjects (p<0.05); cording occurred in six subjects. The time course of phenytoin-induced phlebitis was bimodal. Erythema and tenderness were prominent at the end of the infusion and again at 24 hours. Cording was first noted between 24 hours and 1 week after infusion. In contrast, fosphenytoin was associated with mild pain in two subjects, one incident of phlebitis, and no erythema or cording. Conclusions . Fosphenytoin administration resulted in significantly less venous irritation and phlebitis compared with an equimolar dose of phenytoin. The clinical use of this water-soluble phenytoin prodrug should minimize the frequency and severity of infusion-site reactions and should allow convenient, rapid, intravenous administration of drug, undiluted or admixed with intravenous solutions.  相似文献   
14.
A controversy exists regarding the classification of nonorganic failure to thrive within the psychiatric nomenclature. There are a number of DSM-III-R diagnoses that may be applied to NOFTT, including Reactive Attachment Disorder of Infancy (RADI) and Major Depressive Disorder (MDD). The behaviors characteristic of NOFTT are symptomatic of depression, and are similar to those exhibited by infants with anaclitic depression as well as those of the adult with depression. The correspondence of the behaviours of NOFTT and the DSM-III-R criteria for Major Depression are reviewed, as are the conceptual and therapeutic reasons to view NOFTT infants as suffering from Depression.  相似文献   
15.
16.
Eleven men consumed a basal diet alone and with cellulose (Na-carboxymethylcellulose, locust bean gum, or karaya gum) added at 7.5 g fiber per 1000 calories for 4 wk each. Food, urine, and fecal composites were collected during the last 8 d of each feeding period. Bowel transit time was not significantly affected; however, total dry fecal weight was significantly increased after the refined fibers compared with that after the basal diet. Adding refined fibers to the basal diet did not significantly affect apparent mineral balance of calcium, magnesium, manganese, iron, copper, or zinc, with the exception of a negative mineral balance for manganese with carboxymethylcellulose. Karaya gum had a mean positive balance for all minerals tested. These results indicate that the hypocholesterolemic effect of the fibers that form gels occurs without compromising mineral balance in those subjects consuming Recommended Dietary Allowance levels of the minerals studied.  相似文献   
17.
Between 1 January and 31 March 1986, 2434 strains of Haemophilus influenzae collected from 23 laboratories in the United Kingdom were examined. With the same criteria as previous studies in 1977 and 1981 the prevalence of resistance was: ampicillin 7.8% (6.2% beta-lactamase producers and 1.6% non-producers), tetracycline 2.7%, chloramphenicol 1.7%, trimethoprim 4.2%, and sulphamethoxazole 3.5%. of the 87 capsulated strains, 15 produced beta-lactamase, nine were resistant to ampicillin but did not produce beta-lactamase, and two strains, one of which produced beta-lactamase, were resistant to chloramphenicol and tetracycline. Since 1977 the prevalence of resistance to ampicillin, chloramphenicol, and trimethoprim has increased significantly. During 1981-6 strains resistant to ampicillin but not producing beta-lactamase and strains resistant to trimethoprim have significantly increased.  相似文献   
18.
Summary.  Previously we demonstrated that domain 5 (D5) of high-molecular-weight kininogen (HK) inhibits neovascularization in the chicken chorioallantoic membrane (CAM) assay and further found that kallikrein cleaved HK (HKa) inhibited FGF2-and VEGF-induced neovascularization, and thus was antiangiogenic. In this study, we sought to demonstrate whether uncleaved HK stimulates neovascularization and thus is proangiogenic. The chick chorioallantoic membrane was used as an in ovo assay of angiogenesis. Low-molecular-weight kininogen stimulates angiogenesis, indicating that D5 is not involved. Bradykinin stimulates neovascularization equally to HK and LK and is likely to be responsible for the effect of HK. A murine monoclonal antibody to HK (C11C1) also recognizes a similar component in chicken plasma as detected by surface plasmon resonance. Angiogenesis induced by FGF2 and VEGF is inhibited by this monoclonal antibody and is a more potent inhibitor of neovascularization induced by VEGF than an integrin αvβ3 antibody (LM 609). Our postulate that C11C1 inhibits the stimulation of angiogenesis by HK was confirmed when either C11C1 or D5 completely inhibited angiogenesis in the CAM induced by HK. Growth of human fibrosarcoma (HT-1080) on the CAM was inhibited by GST-D5 and C11C1. These results indicate HK is proangiogenic probably by releasing bradykinin and that a monoclonal antibody directed to HK could serve as an antiangiogenic agent with a potential for inhibiting tumor angiogenesis and other angiogenesis-mediated disorders.  相似文献   
19.
Several major prospective studies that have examined the relation between type A behavior and cardiac mortality have failed to find an association. Since psychosocial factors have been implicated in the etiology of sudden cardiac death, it is possible that this association may emerge if sudden cardiac death is distinguished as an outcome distinct from other cardiac mortality. Predictors of sudden death and other cardiac outcomes were examined using data from the Recurrent Coronary Prevention Project, a 4.5-year prospective clinical trial of 1,012 postinfarction patients begun in San Francisco in 1978. A unique set of risk factors was found for the differing outcomes: sudden cardiac death had predominantly psychosocial predictors while nonsudden cardiac death and nonfatal recurrences were predominantly predicted by biologic factors. Type A behavior was an independent predictor of sudden, but not nonsudden, cardiac death in this population (p = 0.04). These results are the first demonstration of a direct relation between stress and sudden cardiac death in a large prospective clinical study, and provide insight into the failure of past prospective studies to find an association between type A behavior and cardiac mortality.  相似文献   
20.
We describe a simple, quick ultrasound screening test for CDH, and its use in a prospective study of babies with a 'high risk' factor, over one year from January 1987. From a birth population of 3,879, 812 hip scans were performed on 406 babies and 98 babies were abnormal. So far, there have been no late cases of CDH. Family history, breech malposition, and postural foot deformities were confirmed to be important risk factors, but babies with a simple click were equally at risk. Our early results indicate that a large proportion of the potential late cases are contained within our extended high-risk group.  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