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   13284篇
  免费   893篇
  国内免费   47篇
耳鼻咽喉   109篇
儿科学   555篇
妇产科学   307篇
基础医学   1699篇
口腔科学   358篇
临床医学   1451篇
内科学   2426篇
皮肤病学   186篇
神经病学   1097篇
特种医学   408篇
外国民族医学   3篇
外科学   1479篇
综合类   121篇
一般理论   13篇
预防医学   1784篇
眼科学   379篇
药学   904篇
中国医学   22篇
肿瘤学   923篇
  2023年   99篇
  2022年   184篇
  2021年   400篇
  2020年   217篇
  2019年   360篇
  2018年   362篇
  2017年   292篇
  2016年   268篇
  2015年   320篇
  2014年   438篇
  2013年   573篇
  2012年   897篇
  2011年   899篇
  2010年   419篇
  2009年   402篇
  2008年   702篇
  2007年   746篇
  2006年   762篇
  2005年   745篇
  2004年   694篇
  2003年   608篇
  2002年   538篇
  2001年   320篇
  2000年   292篇
  1999年   246篇
  1998年   118篇
  1997年   92篇
  1996年   89篇
  1995年   68篇
  1994年   48篇
  1992年   159篇
  1991年   126篇
  1990年   127篇
  1989年   140篇
  1988年   133篇
  1987年   109篇
  1986年   113篇
  1985年   96篇
  1984年   86篇
  1983年   58篇
  1982年   39篇
  1979年   66篇
  1978年   61篇
  1977年   59篇
  1976年   46篇
  1975年   48篇
  1974年   49篇
  1973年   59篇
  1972年   55篇
  1970年   50篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
The new quinolones represent the latest possibility of specific oral antibiotic treatment of infections caused by gram-negative bacteria. Among the new quinolones, ciprofloxacin and ofloxacin are characterized by strong in vitro activity against most Pseudomonas species strains, favourable kinetic in body fluids, good tolerability and the possibility of oral administration. For these reasons they appear to be ideal antibiotics for long-term home therapy of chronic obstructive pulmonary disease in cystic fibrosis (CF). The efficacy of ciprofloxacin has been recently assessed. In this study, actual effectiveness of ofloxacin in long-term home antibiotic treatment of patients affected by CF was evaluated. The study was a no-blind cross-over study, designed to compare ofloxacin treatment with conventional oral antibiotic therapy. Young adult patients, who needed long-term antibiotic therapy and whom sputum culture were positive for sensitive strains, were randomly assigned to 2 groups. One group received ofloxacin, the other group was given a non-quinolone oral antibiotic, selected according to sputum culture sensitivity. Oral antibiotics were administered for 20 days, then a break of 10 days was allowed during which patients received nebulized aminoglucosides, usually tobramycin. After 3 months, therapies were rotated: the first group received a non-quinolone oral antibiotic and the second group received ofloxacin for another 3 months. The clinical score (according to Huang et al., see table I) and the lung function (FVC, FEV1, pulsed SaO2) were assessed in all the patients at the beginning and at the end of each three months period of oral antibiotic therapy.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
12.
We compared two methods of ascertaining mortality in a historical prospective mortality study. Computerized Record Linkage (CRL) with the centralized historical Canadian Mortality Data Base (CMDB) was carried out on 2469 men and an attempt was also made to trace the subjects by individual follow-up (IFU). All but 88 were traced and 60 were reported to be dead. CRL was able to locate the deaths of three men who had been untraced by IFU. Contradictory information on vital status was obtained on 5 subjects--in 4 of them, the discrepancy was resolved in favour of CRL. Overall, CRL using the CMDB performed very well. We also consider factors that affect the relative costs of the two methods, which should be balanced against the accuracy of information obtained.  相似文献   
13.
Regional cerebral blood flow was studied by means of the 133Xe inhalation method in 26 untreated and 10 treated patients with essential hypertension. The untreated subjects were divided into newly and previously diagnosed groups to assess the relation between regional cerebral blood flow and the duration of hypertension. The overall flow reduction was more marked in the frontal and temporal regions in the previously diagnosed group, and this was attributed to pathological changes in the district served by the middle cerebral artery. Regional temporal lobe impairment was also noted in the newly diagnosed and treated subjects. A significant correlation was found between regional cerebral blood flow and mean arterial blood pressure.  相似文献   
14.
Objectives: To evaluate a group intervention to help individuals with psychiatric disorder stop smoking.
Method: A waitlist-treatment crossover design. Outcome measures included smoking cessation, motivation to stop, the Fagerstrom Test for Nicotine Dependence (FTND), urinary cotinine and psychiatric symptoms on the General Health Questionnaire.
Results: 38 subjects participated, of whom 19 completed the waitlist and intervention phases. There were no significant differences between subjects and dropouts. During the waitlist period there were no significant changes in tobacco use. At the end of the intervention, almost a quarter had stopped smoking, ( z = -2.24, p =0.02). Subjects also showed significant improvements on state of change, FTND score and urinary cotinine levels. These improvements were maintained at three-month follow-up (n=10). Psychiatric morbidity showed no change.
Conclusions: It is possible to reduce smoking in individuals with psychiatric disorder.
Implications: Larger randomised controlled trials are indicated to determine the relative contributions of nicotine replacement, bupropion and group interventions to smoking cessation in this population.  相似文献   
15.
OBJECTIVE: To investigate the effect of screening specimens and different criteria for exclusion of duplicate isolates when surveillance of antimicrobial resistances is performed. MATERIALS AND METHODS: Trends in resistance were analysed for recent isolates of selected organisms from Guy's and St Thomas' Hospitals with the use of various criteria for the exclusion of duplicates, including time since the last isolate and antibiogram pattern, and the effect of excluding screening specimens. RESULTS: There was a significant difference of about 8% in the apparent frequency of methicillin resistance in Staphylococcus aureus in inpatients if the time limit for duplicates was set at 5 rather than 30 days; it was about 10% if a 5 day limit was compared with a 365 day limit. There was also a significant difference, of 6-10%, in apparent resistance frequencies if isolates from screening specimens were excluded. Apparent gentamicin resistance rates in Klebsiella spp. varied between 11% and 28%, and the number of apparent patient isolates of gentamicinresistant organisms varied by up to 35%, depending on the duplicate exclusion criteria chosen. Effects were smaller, though still significant, for vancomycin resistance in Enterococcus spp. There was little effect for amoxicillin or cefuroxime resistance in Escherichia coli isolates from general practitioners, where the proportion of duplicates was small. CONCLUSION: Improved surveillance of antibiotic resistance is needed. However, care needs to be taken in setting the criteria for classifying isolates as duplicates and in comparing results where these criteria may be different or unknown.  相似文献   
16.
17.
OBJECTIVE Hexarelin is a new synthetic growth hormone releasing peptide. We have tested the efficacy of intranasal (i.n.) administration of hexarelin to stimulate plasma GH and have compared this to the intravenous (i.v.) administration of the peptide. PATIENTS Ten children with familial short stature (FSS) aged 5·5-15·5 years and two known GH deficient patients aged 24 and 28 years without GH treatment. METHODS All 12 subjects were submitted to i.v. (1 μg/kg) and i.n. (20 μg/kg) hexarelin tests with a one-week interval between tests. Blood samples for GH, TSH, fT4 and T3 were obtained at 0, 15, 30, 60, 90 and 120 minutes. The hormone determinations were made by standard radio-immunoassays (RIA). RESULTS Both the i.n. and i.v. administration of hexarelin induced a large GH response, the mean (±SD) being 72·2± 35·5 mU/l for the i.n. test and 79·6 ± 53·0 mU/l for the i.v. test. The peak GH in the i.v. test occurred at 15–30 minutes and in the i.n. test between 30 and 60 minutes. The GH deficient patients showed no GH response In either test. Plasma TSH decreased in the FSS children from a mean (±SD) of 1.0 ± 0·26 to 0·64±0 2 mU/l (P<0 005) during the i.n. test and from 1·0±0·3 to 0·7±0·3mU/l (P> 0 05) during the I.v. test. In the isolated GH deficient patient, plasma TSH decreased from 1·06±0·38 mU/l to 0·86±0·17 during the i.v. test and from 1·60±0·01 to 1·11±0·06mU/l during the i.n. test. There were no significant changes in plasma fT4 or T3 in any of the tests. CONCLUSIONS The synthetic hexapeptide hexarelin is a potent pituitary GH stimulator when administered intra-nasally. The GH response was similar to that observed after intravenous hexarelin. Simultaneously, there was a significant decrease in plasma TSH but the concentrations remained in the normal range. These findings appear to be of theoretical and practical relevance to the investigation and management of short children.  相似文献   
18.
19.
OBJECTIVE: The objective of this study is to evaluate the inflammatory response caused by endovascular stents in the treatment of aortic aneurysms. METHODS: Twenty-five patients underwent endovascular stent treatment from March through December 2005. The evolution of mediators (sedimentation velocity, C reactive protein, interleukin-6, interleukin-8, tumor necrosis factor-alpha, intercellular adhesion molecule-1, l-selectin), inflammatory cells (leukocytes, lymphocytes, platelets), serum creatinine and body temperature within preoperative period and in the following postoperative periods--1, 6, 24 and 48 h, 7 days, 1-3 months, was analyzed. In order to achieve statistic significance, Friedman test and Wilcoxon test were used, with index of significance of 5% (p<0.05). RESULTS: Peak values of sedimentation velocity, C reactive protein and interleukin-6 were observed at 7 days (p<0.0001), 48 h (p<0.0001) and 24h (p<0.0001), respectively. Tumor necrosis factor-alpha and interleukin-8 did not show statistically significant variability during the entire follow-up. In terms of intercellular adhesion molecule-1 and l-selectin, their expressive values were found in late phase of follow-up, although without statistical significance. Elevation of leukocytes count occurred in premature phase of follow-up (p<0.0001), while lymphocyte and platelet count occurred in a late phase of follow-up (p<0.0001). Serum levels of creatinine did not show significant variability during follow-up. The period between 24 and 48 h corresponded to major frequency for fever (p<0.0001). CONCLUSION: Individual mediators analysis and inflammatory cells demonstrated variability of their values during postoperative follow-up. This could help in the analysis of the inflammatory response evolution caused by endovascular stent treatment for aortic aneurysms in premature and late phases after implantation of the vascular prosthesis.  相似文献   
20.
We present a patient with a facial movement disorder that has characteristics of both blepharospasm and bilateral asynchronous hemifacial spasm. Because of the increased incidence of blepharospasm in patients with hemifacial spasm, our patient's clinical presentation is probably not a chance occurrence, but rather a manifestation of some predisposition for these two movement disorders. This unusual constellation of signs and symptoms challenges the current diagnostic criteria and suggests that some of these facial movement disorders may lie on a spectrum, rather than represent distinct entities.  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