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   3135篇
  免费   194篇
  国内免费   15篇
耳鼻咽喉   9篇
儿科学   109篇
妇产科学   95篇
基础医学   536篇
口腔科学   71篇
临床医学   332篇
内科学   646篇
皮肤病学   62篇
神经病学   341篇
特种医学   65篇
外科学   291篇
综合类   40篇
一般理论   2篇
预防医学   273篇
眼科学   51篇
药学   200篇
中国医学   8篇
肿瘤学   213篇
  2023年   20篇
  2022年   36篇
  2021年   69篇
  2020年   56篇
  2019年   85篇
  2018年   84篇
  2017年   41篇
  2016年   64篇
  2015年   72篇
  2014年   98篇
  2013年   178篇
  2012年   181篇
  2011年   185篇
  2010年   110篇
  2009年   90篇
  2008年   179篇
  2007年   197篇
  2006年   165篇
  2005年   173篇
  2004年   162篇
  2003年   147篇
  2002年   148篇
  2001年   74篇
  2000年   61篇
  1999年   53篇
  1998年   33篇
  1997年   18篇
  1996年   28篇
  1995年   17篇
  1994年   14篇
  1993年   14篇
  1992年   34篇
  1991年   51篇
  1990年   34篇
  1989年   27篇
  1988年   21篇
  1987年   36篇
  1986年   21篇
  1985年   25篇
  1984年   23篇
  1983年   19篇
  1982年   13篇
  1981年   11篇
  1979年   23篇
  1978年   14篇
  1977年   23篇
  1976年   16篇
  1974年   13篇
  1973年   14篇
  1969年   13篇
排序方式: 共有3344条查询结果,搜索用时 15 毫秒
31.
32.
Background  We previously developed and validated a predictive model to help clinicians identify hospitalized adults with coronavirus disease 2019 (COVID-19) who may be ready for discharge given their low risk of adverse events. Whether this algorithm can prompt more timely discharge for stable patients in practice is unknown. Objectives  The aim of the study is to estimate the effect of displaying risk scores on length of stay (LOS). Methods  We integrated model output into the electronic health record (EHR) at four hospitals in one health system by displaying a green/orange/red score indicating low/moderate/high-risk in a patient list column and a larger COVID-19 summary report visible for each patient. Display of the score was pseudo-randomized 1:1 into intervention and control arms using a patient identifier passed to the model execution code. Intervention effect was assessed by comparing LOS between intervention and control groups. Adverse safety outcomes of death, hospice, and re-presentation were tested separately and as a composite indicator. We tracked adoption and sustained use through daily counts of score displays. Results  Enrolling 1,010 patients from May 15, 2020 to December 7, 2020, the trial found no detectable difference in LOS. The intervention had no impact on safety indicators of death, hospice or re-presentation after discharge. The scores were displayed consistently throughout the study period but the study lacks a causally linked process measure of provider actions based on the score. Secondary analysis revealed complex dynamics in LOS temporally, by primary symptom, and hospital location. Conclusion  An AI-based COVID-19 risk score displayed passively to clinicians during routine care of hospitalized adults with COVID-19 was safe but had no detectable impact on LOS. Health technology challenges such as insufficient adoption, nonuniform use, and provider trust compounded with temporal factors of the COVID-19 pandemic may have contributed to the null result. Trial registration  ClinicalTrials.gov identifier: NCT04570488.  相似文献   
33.
Given its high prevalence, its wide distribution and its remarkable capacity to cause severe mortality in shrimp, the infectious hypodermal and haematopoietic necrosis virus (IHHNV) may deserve far more attention than it has received, as it remains considered as one of the most serious problems plaguing the global shrimp farming industry. Furthermore, its real measurable impact over wild shrimp populations remains unknown. Undeniably, the progress that we have reached today on the knowledge of its geographical distribution, clinical signs, genetic diversity, transmission and virulence may help to identify and understand important aspects of its biology and pathogenesis. However, the information regarding the molecular events that occur during the infection process is scarce. Thus, it may not be surprising to find that there are no therapeutic options available for the prophylaxis or treatments to reduce the deleterious impact of this viral pathogen to date. The aim of this review is to integrate and discuss the current state of knowledge concerning several aspects of the biology of IHHNV and to highlight potential future directions for this area of research.  相似文献   
34.
35.
36.
ObjectiveTo synthesize data quality (DQ) dimensions and assessment methods of real-world data, especially electronic health records, through a systematic scoping review and to assess the practice of DQ assessment in the national Patient-centered Clinical Research Network (PCORnet).Materials and MethodsWe started with 3 widely cited DQ literature—2 reviews from Chan et al (2010) and Weiskopf et al (2013a) and 1 DQ framework from Kahn et al (2016)—and expanded our review systematically to cover relevant articles published up to February 2020. We extracted DQ dimensions and assessment methods from these studies, mapped their relationships, and organized a synthesized summarization of existing DQ dimensions and assessment methods. We reviewed the data checks employed by the PCORnet and mapped them to the synthesized DQ dimensions and methods.ResultsWe analyzed a total of 3 reviews, 20 DQ frameworks, and 226 DQ studies and extracted 14 DQ dimensions and 10 assessment methods. We found that completeness, concordance, and correctness/accuracy were commonly assessed. Element presence, validity check, and conformance were commonly used DQ assessment methods and were the main focuses of the PCORnet data checks.DiscussionDefinitions of DQ dimensions and methods were not consistent in the literature, and the DQ assessment practice was not evenly distributed (eg, usability and ease-of-use were rarely discussed). Challenges in DQ assessments, given the complex and heterogeneous nature of real-world data, exist.ConclusionThe practice of DQ assessment is still limited in scope. Future work is warranted to generate understandable, executable, and reusable DQ measures.  相似文献   
37.
Burnett-Bowie SM  Mendoza N  Leder BZ 《BONE》2007,40(4):913-918
INTRODUCTION: Fibroblast growth factor (FGF-23) is a novel phosphaturic factor. Current data suggest that serum phosphate, dietary phosphate and 1,25 dihydroxyvitamin D regulate circulating FGF-23 levels in vivo. We examined if hypogonadism-induced increases in serum phosphate are associated with increases in circulating FGF-23 in healthy men in the absence of dietary manipulation. MATERIALS AND METHODS: 25 healthy men were administered goserelin acetate (GnRH analog) 3.6 mg subcutaneously every 4 weeks for 12 weeks to induce acute testosterone and estrogen deficiency. Subjects consumed an ad libitum diet. Morning fasting blood and urine samples were collected to measure serum phosphate, serum intact FGF-23, PTH, and the maximum tubular reabsorption of phosphate (T(m)P/GFR) at baseline, weeks 4 and 12. The changes in serum FGF-23 and phosphate at weeks 4 and 12 were compared to baseline using paired t-tests. RESULTS: Goserelin therapy decreased mean serum testosterone levels from 543+/-160 ng/dL to 33+/-15 ng/dL at week 4 (p<0.001), and to 20+/-10 ng/dL at week 12 (p<0.001). Serum phosphate increased significantly from 3.4+/-0.6 mg/dL to 3.9+/-0.4 mg/dL at week 4 (p=0.002), and to 4.3+/-0.4 mg/dL at week 12 (p<0.001). T(m)P/GFR increased significantly from 3.2+/-0.6 mg/dL to 3.6+/-0.5 mg/dL at week 4 (p<0.004), and to 4.1+/-0.6 mg/dL at week 12 (p<0.001). FGF-23 levels, however, did not change during the 12-week study. CONCLUSIONS: Gonadal steroid deprivation increased serum phosphate levels in men but did not affect serum FGF-23 concentrations. The absence of any change in circulating FGF-23 suggests that supraphysiologic levels of serum phosphate may be required to stimulate circulating FGF-23 or that FGF-23 production is primarily sensitive to changes in dietary phosphate or 1,25 dihydroxyvitamin D within this physiologic serum phosphate range.  相似文献   
38.
For the last decades, the latissimus dorsi skin-muscle flap has contributed to the efficient reconstruction of the loss of skin cover (especially in breast surgery) and in long-distance tissue defects. Unfortunately, the nonuse of such an important muscle as the latissimus dorsi for the patient, as well as the resulting thickness of the flap after reconstruction, has turned it into a second choice flap. However, this flap is still indicated in the reconstruction of areas which need a great amount of cutaneous and muscular tissue. The appearance of the perforator flaps and, specifically, thoracodorsal artery perforator (TDAP) flap, has meant a radical change in relation to lower morbidity of the donor site, thus highly ranking the use of these flaps in the reconstruction for similar defects. The aim of this publication is to present our experience with the pedicled TDAP flap in a series of 17 different cases. Of those, there were 14 cases of mammary reconstruction after sparing surgery, 2 cases of axillary reconstruction following severe recurrent hidradenitis, and a case of extensive substance loss in a patient's upper limb following a severe crush injury.  相似文献   
39.
Porcine brucellosis is a disease caused by Brucella suis, which is characterized by reproductive disorders in pigs. The number of cases of swine brucellosis has risen in many European countries, likely because of the presence of a wild reservoir of B. suis in wild boar. This study aimed at evaluating factors that may influence the probability of infection with Brucella spp. in wild boar and at assessing the impact of a previous contact with Brucella spp. on reproductive parameters of wild boar. Two hundred and four wild boar living in Extremadura (south‐western Spain) were studied. The presence of anti‐Brucella antibodies was determined using an indirect ELISA, while the presence of living bacteria in genital organs was evaluated through microbiological cultures. Sex, age, density of wild boar in summer and presence of outdoor pigs were selected as possible risk factors for being seropositive for Brucella spp. in wild boar. In addition, reproductive parameters such as breeding status or potential fertility in females and testis weight in males were estimated and related to the presence of anti‐Brucella antibodies. A total of 121 animals were seropositive, resulting in a prevalence of 59.3% (95% CI). In addition, seven isolates of B. suis biovar 2 were obtained. Wild boar density in summer, as well as age and sex, was proposed as factors to explain the probability of Brucella seroconversion, although wild boar density in summer was the key factor. Current measures of reproductive parameters were not influenced by a previous contact with Brucella spp. Isolation of B. suis confirms that wild boar could represent a risk to domestic pig health in the study area. Wild boar density seems to have a great influence in the probability of infections with B. suis and suggests that density management could be useful to control Brucella infection in wild boar.  相似文献   
40.
The magnitude of the September 11, 2001 (9/11) attacks was without precedent in the United States, but long‐term longitudinal research on its health consequences for primary care patients is limited. We assessed the prevalence and exposure‐related determinants of mental disorders, functioning, general medical conditions, and service utilization, 1 and 4 years after the 9/11 attacks, in an urban primary care cohort (N = 444) in Manhattan. Although the prevalence of posttraumatic stress disorder (PTSD) and levels of functional impairment declined over time, a substantial increase in suicidal ideation and missed work was observed. Most medical outcomes and service utilization indicators demonstrated a short‐term increase after the 9/11 attacks (mean change of +20.3%), followed by a minor decrease in the subsequent year (mean change of ?3.2%). Loss of a close person was associated with the highest risk for poor mental health and functional status over time. These findings highlight the importance of longitudinal assessments of mental, functional, and medical outcomes in urban populations exposed to mass trauma and terrorism.  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