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   939篇
  免费   90篇
耳鼻咽喉   60篇
儿科学   26篇
妇产科学   27篇
基础医学   128篇
口腔科学   22篇
临床医学   131篇
内科学   184篇
皮肤病学   17篇
神经病学   57篇
特种医学   53篇
外科学   119篇
综合类   18篇
预防医学   66篇
眼科学   39篇
药学   47篇
中国医学   2篇
肿瘤学   33篇
  2022年   8篇
  2021年   27篇
  2020年   8篇
  2019年   9篇
  2018年   18篇
  2017年   15篇
  2016年   23篇
  2015年   20篇
  2014年   26篇
  2013年   41篇
  2012年   38篇
  2011年   51篇
  2010年   28篇
  2009年   26篇
  2008年   28篇
  2007年   43篇
  2006年   35篇
  2005年   36篇
  2004年   29篇
  2003年   23篇
  2002年   33篇
  2001年   20篇
  2000年   15篇
  1999年   18篇
  1998年   11篇
  1997年   18篇
  1996年   15篇
  1995年   11篇
  1994年   10篇
  1993年   9篇
  1992年   28篇
  1991年   15篇
  1990年   19篇
  1989年   23篇
  1988年   18篇
  1987年   17篇
  1986年   20篇
  1985年   22篇
  1984年   12篇
  1983年   16篇
  1982年   10篇
  1981年   14篇
  1980年   8篇
  1979年   14篇
  1978年   13篇
  1975年   8篇
  1971年   8篇
  1970年   7篇
  1969年   11篇
  1967年   7篇
排序方式: 共有1029条查询结果,搜索用时 15 毫秒
1.

A key goal for implementation science is the identification of evidence-based consultation protocols and the active ingredients within these protocols that drive clinician behavior change. The current study examined clinicians’ self-coding of fidelity as a potential active ingredient of consultation for the Attachment and Biobehavioral Catch-up (ABC) intervention. It also examined two other potential predictors of clinician fidelity in response to consultation: dosage of consultation and working alliance. Twenty-nine clinicians (97% female, 62% White, M age?=?34 years) participated in a year of weekly fidelity-focused ABC consultation sessions, for which clinicians self-coded fidelity and received consultant feedback on both their coding and their fidelity. Data from the ABC fidelity measure were available for 1067 sessions coded by consultants, and clinicians’ self-coding accuracy was calculated from 1044 sessions coded by both clinicians and consultants. Alliance was measured with the Working Alliance Inventory—Trainee and Supervisor Versions. The study was observational, and fidelity and self-coding accuracy were modeled across time using hierarchical linear modeling. Clinicians’ ABC fidelity, as well as their self-coding accuracy, increased over the course of consultation. Clinicians’ self-coding accuracy predicted their initial fidelity and growth in fidelity. Working alliance was also linked to fidelity and self-coding accuracy. These results suggest that clinician self-coding should be further examined as an active ingredient of consultation. The study has important implications for the design of consultation procedures and fidelity assessments.

  相似文献   
2.
Reduction of transmission of human immunodeficiency virus type 1 (HIV-1) through human milk is needed. Alkyl sulfates such as sodium dodecyl sulfate (SDS) are microbicidal against HIV-1 at low concentrations, have little to no toxicity, and are inexpensive. The authors have reported that treatment of HIV-1-infected human milk with < or = 1% (10 mg/mL) SDS for 10 minutes inactivates cell-free and cell-associated virus. The SDS can be removed with a commercially available resin after treatment without recovery of viral infectivity. In this article, the authors report results of selective biochemical analyses (ie, protein, immunoglobulins, lipids, cells, and electrolytes) of human milk subjected to SDS treatment and removal. The SDS treatment or removal had no significant effects on the milk components studied. Therefore, the use of alkyl sulfate microbicides to treat milk from HIV-1-positive women may be a simple, practical, and nutritionally sound way to prevent or reduce transmission of HIV-1 while still feeding with mother's own milk.  相似文献   
3.
The proteolytic environment in which Candida albicans exists strongly affects its virulence. To determine whether virulence might be related to C. albicans growth in different proteolytic environments, we measured renal fungal load in burned mice and found significantly greater Candida census in kidneys from mice that were challenged with a high proteinase-generating parent C. albicans (MY 1044) versus those that were challenged with its low proteinase-generating mutant (MY 1049). In vitro, MY 1044 cells grew faster than MY 1049 cells in media that contained sera from burned mice as the only nitrogen source. Augmentation of media with proteinase or a mixture of amino acids increased growth of MY 1049 cells, whereas augmentation with proteinase inhibitor decreased MY 1044 growth. In conclusion, in vitro growth of both the mutant and its parent strain was affected by the proteolytic environment in which they existed; thus, virulence differences for MY 1044 and MY 1049 could be due in part to growth differences between these two strains in different proteolytic environments. These results were combined with existing observations, and we proposed a theory for the pathogenesis of C. albicans in burns.  相似文献   
4.
A cross-sectional radiographic screening was performed on bite-wing pairs (BW) from 1872 10-12 year old schoolchildren in the Greater Worcester, Massachusetts area to assess the prevalence of juvenile periodontitis (JP). The 3-stage screening process entailed: (1) visual identification of possible cases based upon a visual assessment of BW for interproximal crestal bone levels greater than or equal to 2 mm from the cemento-enamel junction (CEJ) on greater than or equal to 1 permanent first molar; (2) identification of probable cases based upon BW from possible cases measured with a transparent ruler calibrated in millimeters; (3) finally, clinical confirmation of JP in consenting probable cases. A total of 1038 subjects were eligible to be included in the study (greater than or equal to 3 mesial sites readable). Of the 1038 eligible subjects, 117 possible and 103 probable cases were identified in stage 1 and stage 2, respectively. A total of 99 probable cases could be contacted and 43 were examined clinically. Two cases of JP were confirmed clinically in stage 3, yielding a prevalence rate of 4.6/1000. Specifically, this report defines a rate of JP in 10-12 year-old schoolchildren for the first time. In addition, these results indicate that BW can be used to identify children with JP from large data sets. However, further studies including complete clinical and radiographic examinations are necessary to determine whether this method is adequate for large epidemiologic studies.  相似文献   
5.
6.
We examined calibration and accuracy, precision, sensitivity, specificity, and "hook" effects for recently revised automated choriogonadotropin (hCG) immunoassay systems (Baxter-Dade Stratus II, Abbott IMx intact hCG and total beta hCG) and compared them with a widely used immunoradiometric assay (Hybritech). We estimated hCG in pregnant women, women with trophoblastic disease, nonpregnant young and menopausal women, normal men, and men with testicular tumors. We found clinically unimportant differences in calibration (all calibrated to the 3rd International Standard). Detection of hCG by all four assays was limited by their responses in serum from nonpregnant women and men. Precision within-run was best for the automated instruments, but all four assays had similar between-run precision. The Hybritech, Stratus, and IMx intact assays are specific for intact hCG. The IMx total beta assay quantifies both free beta subunit and beta subunit present in intact hCG. There is a clinically important hook effect in the Hybritech assay but not the Stratus or IMx assays (to 1.2 x 10(6) int. units/L). Results for pregnant women were similar by all four assays. We measured "hCG" to 8 int. units/L in menopausal women, which weakly correlated with concentrations of lutropin and follitropin and was, in part, explained by crossreactivity. There was no sample-probe carryover in either instrument. We found the IMx diluting module as well as results at the extremes of the IMx calibration curves (less than 10, 800-1200 int. units/L) unreliable but encountered no such problems with the Stratus system. Both automated systems involve batch analyzers with limited throughput but provide hCG concentration estimates much more quickly than the Hybritech assay can.  相似文献   
7.
Optical technologies, such as reflectance and fluorescence spectroscopy, have shown the potential to provide improved point-of-care detection methods for cervical neoplasia that are sensitive, specific, and cost-effective. Our specific goals are to analyze the diagnostic potential of reflectance and fluorescence spectra, alone and in combination, to discriminate normal and precancerous cervical tissue in vivo and to identify which classification features contain significant diagnostic information. Reflectance spectra are measured at four source-detector separations and fluorescence emission spectra are measured at 16 excitation wavelengths, from 324 sites in 161 patients. These 20 spectral features are permuted in all possible combinations of one, two, and three; and classification algorithms are developed to evaluate the diagnostic performance of each combination. Algorithms based on fluorescence spectra alone yield better diagnostic performance than those based on reflectance spectra alone. The combination of fluorescence and reflectance do not significantly improve diagnostic performance compared to fluorescence alone, except in the case of discriminating high-grade precancers from columnar normal tissue. In general, fluorescence emission spectra at 330- to 360-nm and 460- to 470-nm excitation provide the best diagnostic performance for separating all pairs of tissue categories.  相似文献   
8.
9.
Summary Rapid ventricular response during episodes of supraventricular tachycardia are often followed, on abrupt cessation of the tachycardia, by prolonged pauses terminated by a sluggish and sometimes erratic escape of a supraventricular pacemaker. Such chronotropic-dromotropic paradoxes are readily reproduced in the animal laboratory following elimination of the sinus node and bilateral decentralization of the stellate ganglia and vagi. This study examined whether left stellate stimulation (0.5, 1, 2, 4, 8 and 16 Hz) or lack thereof differentially affected AV junctional automaticity and AV conduction. In the absence of any sympathetic neural activity (maximal sympathetic deficit), the AV junctional rate averaged a mere 22±2 percent of its peak performance, whereas under the same conditions, anterograde AV conduction averaged 73±5 percent and retrograde VA conduction 56 ±13 percent of their respective peak performances. On comparing the response curve (normalized responses) for AV junctional automaticity with that obtained for anterograde AV conduction the differences were significant at all frequencies between 0 and 4 Hz. Retrograde VA conduction (as assessed by the fastest ventricular pacing rate still conducted 11 to the atria) was always significantly less than anterograde AV conduction (as assessed by the fastest atrial pacing still conducted 11 to the ventricles). These results indicate that AV junctional automaticity is considerably more affected by sympathetic deficit than are either anterograde or retrograde AV conduction. In other words, AV junctional automaticity is far more dependent upon sympathetic input than AV conduction. While sympathetic influence is critical to the escape and maintenance of AV junctional automaticity both anterograde and retrograde AV conduction are remarkably resilient even under conditions of severe sympathetic deficit.  相似文献   
10.
Antimicrobial resistance   总被引:1,自引:0,他引:1  
  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