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   9511篇
  免费   470篇
  国内免费   169篇
耳鼻咽喉   57篇
儿科学   50篇
妇产科学   51篇
基础医学   1624篇
口腔科学   739篇
临床医学   959篇
内科学   2161篇
皮肤病学   100篇
神经病学   542篇
特种医学   258篇
外科学   904篇
综合类   609篇
预防医学   604篇
眼科学   85篇
药学   860篇
  1篇
中国医学   442篇
肿瘤学   104篇
  2024年   31篇
  2023年   181篇
  2022年   978篇
  2021年   1007篇
  2020年   335篇
  2019年   291篇
  2018年   305篇
  2017年   282篇
  2016年   247篇
  2015年   282篇
  2014年   458篇
  2013年   689篇
  2012年   337篇
  2011年   424篇
  2010年   306篇
  2009年   357篇
  2008年   320篇
  2007年   297篇
  2006年   302篇
  2005年   218篇
  2004年   214篇
  2003年   203篇
  2002年   178篇
  2001年   151篇
  2000年   122篇
  1999年   108篇
  1998年   105篇
  1997年   98篇
  1996年   106篇
  1995年   103篇
  1994年   83篇
  1993年   74篇
  1992年   93篇
  1991年   99篇
  1990年   85篇
  1989年   72篇
  1988年   70篇
  1987年   57篇
  1986年   69篇
  1985年   63篇
  1984年   51篇
  1983年   43篇
  1982年   57篇
  1981年   29篇
  1980年   32篇
  1979年   28篇
  1978年   29篇
  1977年   12篇
  1976年   25篇
  1975年   10篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
The test-retest variability of a series of auditory functions has been investigated in a group of severely hearing-impaired and deaf subjects (64 ears, median Fletcher index: 80 dB) and in a group of 10 controls with normal hearing. An adaptive forced-choice procedure was used for both groups. The functions were: tone audiogram, difference limen for intensity, difference limen for frequency, modulation transfer function and critical ratio. In spite of sometimes strongly deviating function values within the hearing-impaired group, the test-retest variability of the two groups was found to be of the same order of magnitude, except for the tone audiogram where the variability in the hearing-impaired group was twice that for the control group.

Nous avons examiné la variabilité des mesures répétées de quelques fonctions auditives dans un groupe de sujets ayant des troubles auditifs importants (64 oreilles; médiane de l'index de Fletcher 80 dB). Par comparaison nous avons aussi examiné un groupe de 10 sujets ayant une audition normale. Dans les deux groupes nous avons utilisé une procédure adaptive et de choix forcé. Nous avons examiné les seuils auditifs, les seuils différentiels d'intensité et de fréquence, la fonction de transfert de modulation et le rapport critique. Malgré les anomalies majeures du groupe des malentendants, la variabilité des mesures dans les deux groupes est équivalente, à l'exception de la variabilité des seuils auditifs qui est deux fois plus grande chez les malentendants.  相似文献   
172.
The mechanical function of many matrix molecules is unknown. A common method to determine whether a molecule is a load-carrying structural molecule is to measure the mechanical properties of a tissue, digest the tissue with an enzyme specific for cleaving that molecule, and then remeasure the mechanical properties. A limitation of this technique is that there are no specific lytic enzymes for most molecules of interest. This article introduces a method that may allow evaluation of a large number of candidate structural molecules. A translated thrombin proteolytic recognition and cleavage site is inserted in the cDNA of a target molecule, and the target molecule then expressed in a cell that produces a tissue. After growing the tissue with cells expressing the engineered target molecule, the traditional procedure of mechanical testing, digesting, and retesting is performed. This method was demonstrated using decorin and its dermatan sulfate (DS) glycosaminoglycan chain in a neocartilage. A tissue was generated with cells expressing a genetically engineered decorin with a thrombin cleavage site. The tissue was then tested in tension and compression, digested with thrombin, and mechanically retested. The decorin protein was found in the tissue, the DS glycosaminoglycan chain was removed with thrombin digestion, and there was no change in the mechanical properties of the tissue due to the thrombin digestion relative to controls. These findings were in agreement with previously reported tests on decorin, collectively supporting the proposed method. All methods involving animals were reviewed and approved by our Institutional Review Board.  相似文献   
173.
ObjectiveTo assess reliability, construct validity, responsiveness, and interpretability for Neck OutcOme Score (NOOS), Neck Disability Index (NDI), and Short Form–36 (SF-36) in neck pain patients.Study Design and SettingInternal consistency was assessed by Cronbach alpha. Test-retest reliability was evaluated by intraclass correlation coefficient (ICC), and measurement error was estimated from the standard error of measurement. Responsiveness was assessed as standardized response mean (SRM) and interpretability from the minimal important difference (MID). Construct validity was tested correlating subscale scores from NOOS and SF-36 and NDI items.ResultsAt baseline, 196 neck pain patients were included. Cronbach α was adequate for most NOOS subscales, NDI, and SF-36 with few exceptions. Good to excellent reliability was found for NOOS subscales (ICC 0.88–0.95), for NDI, and for SF-36 with few exceptions. For NOOS, minimal detectable changes varied between 1.1 and 1.9, and construct validity was supported. SRMs were higher for NOOS subscales (0.19–0.42), compared to SF-36 and NDI. MID values varied between 15.0 and 24.1 for NOOS subscales.ConclusionsIn conclusion, the NOOS is a reliable, valid, and responsive measure of self-reported disability in neck pain patients, performing at least as well or better than the commonly used SF-36 and NDI.  相似文献   
174.
Abstract

Positive blood cultures were found in 41 patients on the Spinal Cord Injury Service at the Milwaukee VAMC during the period of July, 1980 to December, 1985 giving an incidence of bacteremia of 1.3%. Mortality rate was 17%. Most common pathogens were E. Coli, Proteus mirabilis, Serratia marcescens and Staphylococcus aureus. A review of 29 available charts revealed genitourinary and respiratory tracts as the most common sources of infection (72.4% and 10.3% respectively). Other sources of infection were skin, postoperative, intravenous catheter site and cellulitis. Initial febrile response was seen in 93.1% of patients with 48.1% having temperature greater than 38.3°C. Hypotension (blood pressure less than 90/50 mm Hg) was noted in five out of the 29 (17.1%) patients. Clinical diagnosis of disseminated intravascular coagulation was made in two out of the 29 (6.9%) patients. Underlying risk factors were poor nutrition, respirator dependency, indwelling Foley catheters and manipulative procedures. Incidence and mortality rates are similar to the non-SCI population as reported elsewhere. The risk factors are different; therefore preventive management is extremely important.  相似文献   
175.
《Annals of epidemiology》2014,24(4):246-253
PurposeMeasuring ethnicity accurately is important for identifying ethnicity variations in disease risk. We evaluated the degree of agreement and accuracy of maternal ethnicity measured using the new standardized closed-ended geographically based ethnicity question and geographic reclassification of open-ended ethnicity questions from the Canadian census.MethodsA prospectively designed study of respondent agreement of mothers of healthy children aged 1–5 years recruited through the TARGet Kids! practice-based research network. For the primary analysis, the degree of agreement between geographic reclassification of the Canadian census maternal ethnicity variables and the new geographically based closed-ended maternal ethnicity variable completed by the same respondent was evaluated using a kappa analysis.ResultsEight hundred sixty-two mothers who completed both measures of ethnicity were included in the analysis. The kappa agreement statistic for the two definitions of maternal ethnicity was 0.87 (95% confidence interval, 0.84–0.90) indicating good agreement. Overall accuracy of the measurement was 93%. Sensitivity and specificity ranged from 83% to 100% and 96% to 100%, respectively.ConclusionsThe new standardized closed-ended geographically based ethnicity question represents a practical alternative to widely used open-ended ethnicity questions. It may reduce risk of misinterpretation of ethnicity by respondents, simplify analysis, and improve the accuracy of ethnicity measurement.  相似文献   
176.
McElroy and Shevlin (2014) developed the 33-item Cyberchondria Severity Scale (CSS) to allow for a multidimensional assessment of cyberchondria (compulsion, distress, excessiveness, reassurance, and mistrust of medical professional). The present study evaluated psychometric properties of the CSS, including its factor structure, internal consistency, convergent validity, and incremental validity, using a large sample of community adults located in the United States (N = 539). Results from a confirmatory factor analysis (CFA) supported the adequacy of the five-factor structure of the CSS. However, results from a higher-order CFA indicated that the mistrust of medical professional factor does not assess the same construct as the other factors of the CSS. The CSS scales evidenced adequate internal consistency and significantly correlated with health anxiety. The distress, excessiveness, and mistrust of medical professional scales correlated significantly more strongly with health anxiety than obsessive–compulsive symptoms and these three scales were the only CSS scales to share unique variance with health anxiety. Implications of these results for future research are discussed.  相似文献   
177.
Seamless phase II/III clinical trials have attracted increasing attention recently. They mainly use Bayesian response adaptive randomization (RAR) designs. There has been little research into seamless clinical trials using frequentist RAR designs because of the difficulty in performing valid statistical inference following this procedure. The well-designed frequentist RAR designs can target theoretically optimal allocation proportions, and they have explicit asymptotic results. In this paper, we study the asymptotic properties of frequentist RAR designs with adjusted target allocation proportions, and investigate statistical inference for this procedure. The properties of the proposed design provide an important theoretical foundation for advanced seamless clinical trials. Our numerical studies demonstrate that the design is ethical and efficient.  相似文献   
178.
Background: Hyperkyphosis is associated with physical impairments, activity limitations, and reduced quality of life. Therefore, a simple, reliable, responsive, and valid clinical measure of dorsal kyphosis would be valuable to clinicians. Objective: To describe a novel procedure for measuring kyphotic curvature—the inclinometric kyphosis measure (IKM)—and provide an estimation of reliability, responsiveness, and validity. Methods: During 2 sessions spaced days apart, we used a bubble inclinometer to measure dorsal kyphosis in 68 patients receiving outpatient physical therapy. We also documented occiput-to-wall status and tragus-to-wall distance. Results: Intra-rater reliability of the IKM was supported by intra-class correlation coefficients (ICC3,1) of 0.94 and 0.91 for relaxed and cued conditions, respectively. Responsiveness, as indicated by minimal detectable change, was 8.0 and 10.0 degrees under relaxed and cued conditions, respectively. Validity was supported by significant correlations between the IKM and tragus-to-wall and by differences in the IKM between: 1) relaxed and cued conditions; 2) patients who could and could not touch occiput to the wall; and 3) patients who were older versus younger than 50 years of age. Conclusions: The IKM is a simple, reliable, responsive, and valid method for assessing posture in patients with musculoskeletal conditions.  相似文献   
179.
AimsTo describe a surveillance approach for monitoring the effect of improvement initiatives on hospital-acquired pressure injuries and findings arising from that surveillance.MethodsRandom sampling of patients on the same day of each successive month from a campus of child and adult hospitals using a standard audit tool to identify presence of hospital-acquired pressure injury. Where multiple pressure injuries were present, the most severe grade injury contributed to prevalence. Statistical process control charts were used to monitor monthly performance and Maximum Likelihood Estimation to determine timing of step change.Results8274 patients were assessed over 3 years from an eligible population of 32,259 hospitalised patients. 517 patients had hospital-acquired pressure injuries giving an overall prevalence of 6.2% (95% CI 5.7–6.8%). Annual prevalence was 8.4% (95% CI 7.4–9.5%) in the first year, falling to 5.6% (95% CI 4.7–6.4%) in the second year and 4.8% (95% CI 4.0–5.6%) in the third year. A step change was signalled with mean prevalence up to July 2013 being 7.9% (95% CI 7.1–8.8%) and mean prevalence thereafter 4.8% (95% CI 4.2–5.4%). Hospital-acquired pressure injuries were found in all age ranges, but were more frequent in children up to 14 years (17.4%) and those aged 75 years or older (38.7%).ConclusionMonthly random sampling of patients within clinical units can be used to monitor performance improvement. This approach represents a rational alternative to cross-sectional prevalence surveys especially if the focus is on performance improvement.  相似文献   
180.
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