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   197921篇
  免费   20056篇
  国内免费   8148篇
耳鼻咽喉   761篇
儿科学   4644篇
妇产科学   1160篇
基础医学   16069篇
口腔科学   2120篇
临床医学   25138篇
内科学   27391篇
皮肤病学   1036篇
神经病学   11858篇
特种医学   8839篇
外国民族医学   103篇
外科学   24282篇
综合类   37784篇
现状与发展   28篇
一般理论   2篇
预防医学   13930篇
眼科学   2167篇
药学   19239篇
  201篇
中国医学   10490篇
肿瘤学   18883篇
  2024年   305篇
  2023年   3673篇
  2022年   5073篇
  2021年   9482篇
  2020年   9031篇
  2019年   7004篇
  2018年   6816篇
  2017年   7749篇
  2016年   8136篇
  2015年   8149篇
  2014年   13279篇
  2013年   14892篇
  2012年   12253篇
  2011年   13486篇
  2010年   10800篇
  2009年   10319篇
  2008年   10240篇
  2007年   10511篇
  2006年   9525篇
  2005年   8588篇
  2004年   7046篇
  2003年   6323篇
  2002年   4759篇
  2001年   4248篇
  2000年   3603篇
  1999年   2808篇
  1998年   2266篇
  1997年   2099篇
  1996年   1758篇
  1995年   1679篇
  1994年   1468篇
  1993年   1123篇
  1992年   1075篇
  1991年   839篇
  1990年   745篇
  1989年   678篇
  1988年   582篇
  1987年   516篇
  1986年   445篇
  1985年   586篇
  1984年   404篇
  1983年   275篇
  1982年   305篇
  1981年   281篇
  1980年   239篇
  1979年   191篇
  1978年   127篇
  1977年   108篇
  1976年   87篇
  1975年   61篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.

Background

Early interdisciplinary rehabilitation (EIR) in neurointensive care is a limited resource reserved for patients with moderate to severe traumatic brain injury (TBI) believed to profit from treatment. We evaluated how key parameters related to injury severity and patient characteristics were predictive of receiving EIR, and whether these parameters changed over time.

Methods

Among 1003 adult patients with moderate to severe TBI admitted over 72 h to neurointensive care unit during four time periods between 2005 and 2020, EIR was given to 578 and standard care to 425 patients. Ten selection criteria thought to best represent injury severity and patient benefit were evaluated (Glasgow Coma Scale, Head Abbreviated Injury Scale, New-Injury-Severity-Scale, intracranial pressure monitoring, neurosurgery, age, employment, Charlson Comorbidity Index, severe psychiatric disease, and chronic substance abuse).

Results

In multivariate regression analysis, patients who were employed (adjOR 1.99 [95% CI 1.41, 2.80]), had no/mild comorbidity (adjOR 3.15 [95% CI 1.72, 5.79]), needed neurosurgery, had increasing injury severity and were admitted by increasing time period were more likely to receive EIR, whereas receiving EIR was less likely with increasing age (adjOR 0.97 [95% CI 0.96, 0.98]) and chronic substance abuse. Overall predictive ability of the model was 71%. Median age and comorbidity increased while employment decreased from 2005 to 2020, indicating patient selection became less restrictive with time.

Conclusion

Injury severity and need for neurosurgery remain important predictors for receiving EIR, but the importance of age, employment, and comorbidity have changed over time. Moderate prediction accuracy using current clinical criteria suggest unrecognized factors are important for patient selection.  相似文献   
82.
[摘要] 目的 探讨ICU患者发生产超广谱β-内酰胺酶(extended spectrum beta-lactamases, ESBLs)革兰阴性杆菌感染的危险因素,并构建相关预测模型。方法 选取2017年5月—2021年4月我院ICU发生大肠埃希菌或肺炎克雷伯菌感染的189例患者作为研究对象,收集患者的临床资料,使用单因素分析、LASSO回归和多因素Logistic回归分析ICU患者30 d内发生产ESBLs革兰阴性杆菌感染的危险因素,并据此建立列线图预测模型。结果 急性生理与慢性健康评分≥16分、留置尿管时长≥7 d、抑酸剂使用时长≥3 d、第三代头孢菌素使用时长≥3 d、抗菌药物联用时长≥3 d和ICU住院时间≥15 d是ICU患者30 d内发生产ESBLs革兰阴性杆菌感染的危险因素(P均<0.05)。依此建立预测ICU患者30 d内发生产ESBLs革兰阴性杆菌感染的列线图风险模型,模型验证结果显示C-index为0.795,校正曲线趋近于理想曲线,AUC为0.807(95%CI:0.775~0.839),在2%~81%预测范围内,列线图净获益。结论 ICU患者30 d内发生产ESBLs革兰阴性杆菌感染的危险因素包括APACHEⅡ评分≥16分、留置尿管时长≥7 d、抑酸剂使用时长≥3 d、第三代头孢菌素使用时长≥3 d、抗菌药物联用时长≥3 d和ICU住院时间≥15 d,据此构建的列线图模型能有效预测ICU患者30 d内发生产ESBLs革兰阴性杆菌感染的风险概率,具有一定的临床价值。  相似文献   
83.
《Vaccine》2022,40(6):934-944
Respiratory Syncytial Virus (RSV) remains a leading cause of severe respiratory disease for which no licensed vaccine is available. We have previously described the derivation of an RSV Fusion protein (F) stabilized in its prefusion conformation (preF) as vaccine immunogen and demonstrated superior immunogenicity in naive mice of preF versus wild type RSV F protein, both as protein and when expressed from an Ad26 vaccine vector. Here we address the question if there are qualitative differences between the two vaccine platforms for induction of protective immunity. In naïve mice, both Ad26.RSV.preF and preF protein induced humoral responses, whereas cellular responses were only elicited by Ad26.RSV.preF. In RSV pre-exposed mice, a single dose of either vaccine induced cellular responses and strong humoral responses. Ad26-induced RSV-specific cellular immune responses were detected systemically and locally in the lungs. Both vaccines showed protective efficacy in the cotton rat model, but Ad26.RSV.preF conferred protection at lower virus neutralizing titers in comparison to RSV preF protein. Factors that may contribute to the protective capacity of Ad26.RSV.preF elicited immunity are the induced IgG2a antibodies that are able to engage Fcγ receptors mediating Antibody Dependent Cellular Cytotoxicity (ADCC), and the induction of systemic and lung resident RSV specific CD8 + T cells. These data demonstrate qualitative improvement of immune responses elicited by an adenoviral vector based vaccine encoding the RSV preF antigen compared to the subunit vaccine in small animal models which may inform RSV vaccine development.  相似文献   
84.
ObjectiveAdenocarcinoma (AC) is the number one pathological entity of lung cancer with approximately 30–40% of cases. It is known to be heterogeneous and has 5 histopathological growth patterns. We evaluated the long-term survival rates of patients with predominant subtypes.Methods290 patients with AC underwent pulmonary resection between 2012 and 2017 at our institution. We excluded all patients with lymph node involvement and distant metastases. Hence, 163 patients were included for further analysis. Predominant growth pattern was defined if more than 10% of cells showed a growth pattern. 1, 3, and 5-year survival rates were evaluated. Survival was assessed by Kaplan-Meier curves and the Cox proportional hazards model was used to identify prognostic factors for overall survival.ResultsPredominant growth patterns >10% were compared to <10% growth patterns of the same subtype. 1-year, 3-year, and 5-year overall survival rates of patients with predominant solid tumor growth >10% differed significantly from patients with <10% (88.4% vs. 97.6%, p = 0.04; 65.8% vs. 87.4% p = 0.001, 36.4% vs. 65.9% p = 0.01). Survival rates did not differ between >10% papillary and acinar growth compared to <10%. Kaplan-Meier curves showed reduced overall survival for patients with solid tumor growth >10% (log-rank 0.002). Solid tumor growth >10% was an independent prognostic factor for worse long-term survival (Hazard ratio: 3.05, p = 0.01).ConclusionOur study demonstrates that the presence of a predominant solid pattern in pulmonary adenocarcinoma is a factor for an unfavorable prognosis. This should be kept in mind in daily clinical practice.  相似文献   
85.
86.
ObjectivesDonor-specific cell-free DNA shows promise as a noninvasive marker for allograft rejection, but as yet has not been validated in both adult and pediatric recipients. The study objective was to validate donor fraction cell-free DNA as a noninvasive test to assess for risk of acute cellular rejection and antibody-mediated rejection after heart transplantation in pediatric and adult recipients.MethodsPediatric and adult heart transplant recipients were enrolled from 7 participating sites and followed for 12 months or more with plasma samples collected immediately before all endomyocardial biopsies. Donor fraction cell-free DNA was extracted, and quantitative genotyping was performed. Blinded donor fraction cell-free DNA and clinical data were analyzed and compared with a previously determined threshold of 0.14%. Sensitivity, specificity, negative predictive value, positive predictive value, and receiver operating characteristic curves were calculated.ResultsA total of 987 samples from 144 subjects were collected. After applying predefined clinical and technical exclusions, 745 samples from 130 subjects produced 54 rejection samples associated with the composite outcome of acute cellular rejection grade 2R or greater and pathologic antibody-mediated rejection 2 or greater and 323 healthy samples. For all participants, donor fraction cell-free DNA at a threshold of 0.14% had a sensitivity of 67%, a specificity of 79%, a positive predictive value of 34%, and a negative predictive value of 94% with an area under the curve of 0.78 for detecting rejection. When analyzed independently, these results held true for both pediatric and adult cohorts at the same threshold of 0.14% (negative predictive value 92% and 95%, respectively).ConclusionsDonor fraction cell-free DNA at a threshold of 0.14% can be used to assess for risk of rejection after heart transplantation in both pediatric and adult patients with excellent negative predictive value.  相似文献   
87.
88.
目的探讨儿童心脏神经官能症的发生诱因。方法选取2017年1月至2020年4月本院门诊部及住院部收治的70例心脏神经官能症患儿作为研究对象,分析患儿疾病诱发因素。结果 70例患儿中,肺炎支原体感染26例(37.1%),EB病毒感染15例(21.4%),情绪不良20例(28.6%),ASO升高5例(7.2%),其他4例(5.7%)。结论导致儿童出现心脏神经官能症的因素较多,其中最常见因素包括肺炎支原体感染、EB病毒感染、不良情绪等,临床医师需根据诱因消除疾病症状。  相似文献   
89.
《Drug discovery today》2022,27(1):223-233
Approaches based on animal and two-dimensional (2D) cell culture models cannot ensure reliable results in modeling novel pathogens or in drug testing in the short term; therefore, there is rising interest in platforms such as organoids. To develop a toolbox that can be used successfully to overcome current issues in modeling various infections, it is essential to provide a framework of recent achievements in applying organoids. Organoids have been used to study viruses, bacteria, and protists that cause, for example, respiratory, gastrointestinal, and liver diseases. Their future as models of infection will be associated with improvements in system complexity, including abilities to model tissue structure, a dynamic microenvironment, and coinfection.Teaser.Organoids are a flexible tool for modelling viral, bacterial and protist infections. They can provide fast and reliable information on the biology of pathogens and in drug screening, and thus have become essential in combatting emerging infectious diseases.  相似文献   
90.
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