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   7660篇
  免费   447篇
  国内免费   44篇
耳鼻咽喉   80篇
儿科学   187篇
妇产科学   180篇
基础医学   1107篇
口腔科学   322篇
临床医学   616篇
内科学   1350篇
皮肤病学   117篇
神经病学   758篇
特种医学   526篇
外科学   1189篇
综合类   35篇
一般理论   2篇
预防医学   393篇
眼科学   205篇
药学   535篇
中国医学   14篇
肿瘤学   535篇
  2023年   40篇
  2022年   94篇
  2021年   212篇
  2020年   145篇
  2019年   172篇
  2018年   182篇
  2017年   168篇
  2016年   223篇
  2015年   255篇
  2014年   315篇
  2013年   461篇
  2012年   587篇
  2011年   583篇
  2010年   354篇
  2009年   309篇
  2008年   509篇
  2007年   496篇
  2006年   446篇
  2005年   422篇
  2004年   363篇
  2003年   358篇
  2002年   344篇
  2001年   70篇
  2000年   50篇
  1999年   66篇
  1998年   59篇
  1997年   45篇
  1996年   60篇
  1995年   60篇
  1994年   43篇
  1993年   29篇
  1992年   42篇
  1991年   31篇
  1990年   23篇
  1989年   27篇
  1988年   27篇
  1987年   33篇
  1986年   26篇
  1985年   31篇
  1984年   29篇
  1983年   22篇
  1982年   26篇
  1981年   17篇
  1980年   18篇
  1979年   18篇
  1978年   15篇
  1977年   18篇
  1974年   19篇
  1969年   14篇
  1967年   18篇
排序方式: 共有8151条查询结果,搜索用时 437 毫秒
961.
962.

Aims/hypothesis

We examined whether analysis of lipids by ultra-performance liquid chromatography (UPLC) coupled to MS allows the development of a laboratory test for non-alcoholic fatty-liver disease (NAFLD), and how a lipid-profile biomarker compares with the prediction of NAFLD and liver-fat content based on routinely available clinical and laboratory data.

Methods

We analysed the concentrations of molecular lipids by UPLC-MS in blood samples of 679 well-characterised individuals in whom liver-fat content was measured using proton magnetic resonance spectroscopy (1H-MRS) or liver biopsy. The participants were divided into biomarker-discovery (n?=?287) and validation (n?=?392) groups to build and validate the diagnostic models, respectively.

Results

Individuals with NAFLD had increased triacylglycerols with low carbon number and double-bond content while lysophosphatidylcholines and ether phospholipids were diminished in those with NAFLD. A serum-lipid signature comprising three molecular lipids (‘lipid triplet’) was developed to estimate the percentage of liver fat. It had a sensitivity of 69.1% and specificity of 73.8% when applied for diagnosis of NAFLD in the validation series. The usefulness of the lipid triplet was demonstrated in a weight-loss intervention study.

Conclusions/interpretation

The liver-fat-biomarker signature based on molecular lipids may provide a non-invasive tool to diagnose NAFLD, in addition to highlighting lipid molecular pathways involved in the disease.  相似文献   
963.
964.
Full-length tissue factor (flTF), the coagulation initiator, is overexpressed in breast cancer (BrCa), but associations between flTF expression and clinical outcome remain controversial. It is currently not known whether the soluble alternatively spliced TF form (asTF) is expressed in BrCa or impacts BrCa progression. We are unique in reporting that asTF, but not flTF, strongly associates with both tumor size and grade, and induces BrCa cell proliferation by binding to β1 integrins. asTF promotes oncogenic gene expression, anchorage-independent growth, and strongly up-regulates tumor expansion in a luminal BrCa model. In basal BrCa cells that constitutively express both TF isoforms, asTF blockade reduces tumor growth and proliferation in vivo. We propose that asTF plays a major role in BrCa progression acting as an autocrine factor that promotes tumor progression. Targeting asTF may comprise a previously unexplored therapeutic strategy in BrCa that stems tumor growth, yet does not impair normal hemostasis.  相似文献   
965.
Several guidelines recommended routine use of Disease Activity Score-28 (DAS28) to monitor disease and the response to treatment for rheumatoid arthritis (RA). In practice, it may be appropriate to use historical erythrocyte sedimentation rate (ESR) values in place of same-day ESR, thereby preventing unnecessary delay in adjusting intervention. We asked whether ESR blood samples taken up to 3 months prior to the clinic appointment were adequate to accurately assess RA disease activity using the DAS28. RA patients (N?=?66) who met the inclusion criteria were assessed at baseline and ESR obtained on the day of review to calculate the DAS28 and compared with the DAS28 derived from the latest previous ESR (mean interval, 38.6 days; range, 6–99 days). Limits of agreement (LoA) were used to assess the agreement between the DAS28 pairs. The mean age of the participants was 61.5 years (range, 20–83 years), with mean disease duration of 11.0 years (range, 0.1–40 years). Comparing the DAS28 using same-day ESR versus pre-recorded historical ESR showed a small statistical difference (mean, ?0.09; 95 %CI, ?0.1602 to ?0.017) in the DAS28 score. The calculated LoA (?0.66 and 0.48) demonstrated acceptable agreement between DAS28 pairs, with 7.6 % of patients residing outside the LoA, all of whom had a significant treatment change. Disease misclassification occurred in 9.1 % of patients who were close to disease activity boundaries. Our results indicate that differences in the DAS28 due to a previous or same-day ESR are unlikely to be clinically significant for RA patients with established disease. A decision to adjust treatment therefore may be confidently made for most patients using the most recent ESR for calculating the DAS28, provided there was no major change in treatment since the last ESR measurement.  相似文献   
966.
967.
968.
969.
This study aimed to investigate the prevalence of resistance to second-line antituberculosis (anti-TB) drugs and its association with resistance-related mutations in Mycobacterium tuberculosis isolated in China. In the present study, we collected 380 isolates from a population-based study in China and tested the drug susceptibility to first- and selected second-line drugs. These results were compared with polymorphisms in the DNA sequences of genes associated with drug resistance and MIC values of the studied second-line drugs. Of 43 multidrug-resistant M. tuberculosis isolates, 13 showed resistance to fluoroquinolones or injectable second-line drugs (preextensively drug-resistant TB [pre-XDR-TB]), and 4 were resistant to both and thus defined as extensively drug-resistant TB (XDR-TB). Age and previous TB therapy, including use of second-line drugs, were two independent factors associated with increased resistance to both first- and second-line drugs. Molecular analysis identified the most frequent mutations in the resistance-associated genes: D94G in gyrA (29.1%) and A1401G in rrs (30.8%). Meanwhile, all 4 XDR-TB isolates had a mutation in gyrA, and 3 of them carried the A1401G mutation in rrs. Mutations in gyrA and rrs were associated with high-level resistance to fluoroquinolones and the second-line injectable drugs. In addition to the identification of resistance-associated mutations and development of a rapid molecular test to diagnose the second-line drug resistance, it should be a priority to strictly regulate the administration of second-line drugs to maintain their efficacy to treat multidrug-resistant TB.  相似文献   
970.
Abstract

To evaluate the construct validity and the inter-rater reliability of the Dutch Activity Measure for Post-Acute Care “6-clicks” Basic Mobility short form measuring the patient’s mobility in Dutch hospital care. First, the “6-clicks” was translated by using a forward-backward translation protocol. Next, 64 patients were assessed by the physiotherapist to determine the validity while being admitted to the Internal Medicine wards of a university medical center. Six hypotheses were tested regarding the construct “mobility” which showed that: Better “6-clicks” scores were related to less restrictive pre-admission living situations (p?=?0.011), less restrictive discharge locations (p?=?0.001), more independence in activities of daily living (p?=?0.001) and less physiotherapy visits (p?<?0.001). A correlation was found between the “6-clicks” and length of stay (r=??0.408, p?=?0.001), but not between the “6-clicks” and age (r=??0.180, p?=?0.528). To determine the inter-rater reliability, an additional 50 patients were assessed by pairs of physiotherapists who independently scored the patients. Intraclass Correlation Coefficients of 0.920 (95%CI: 0.828–0.964) were found. The Kappa Coefficients for the individual items ranged from 0.649 (walking stairs) to 0.841 (sit-to-stand). The Dutch “6-clicks” shows a good construct validity and moderate-to-excellent inter-rater reliability when used to assess the mobility of hospitalized patients.
  • Implications for Rehabilitation
  • Even though various measurement tools have been developed, it appears the majority of physiotherapists working in a hospital currently do not use these tools as a standard part of their care.

  • The Activity Measure for Post-Acute Care “6-clicks” Basic Mobility is the only tool which is designed to be short, easy to use within usual care and has been validated in the entire hospital population.

  • This study shows that the Dutch version of the Activity Measure for Post-Acute Care “6-clicks” Basic Mobility form is a valid, easy to use, quick tool to assess the basic mobility of Dutch hospitalized patients.

  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