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   2521篇
  免费   133篇
  国内免费   10篇
耳鼻咽喉   14篇
儿科学   36篇
妇产科学   54篇
基础医学   274篇
口腔科学   210篇
临床医学   144篇
内科学   587篇
皮肤病学   28篇
神经病学   221篇
特种医学   178篇
外科学   438篇
综合类   5篇
预防医学   92篇
眼科学   34篇
药学   153篇
中国医学   6篇
肿瘤学   190篇
  2024年   5篇
  2023年   15篇
  2022年   57篇
  2021年   91篇
  2020年   54篇
  2019年   68篇
  2018年   59篇
  2017年   76篇
  2016年   64篇
  2015年   85篇
  2014年   104篇
  2013年   150篇
  2012年   179篇
  2011年   175篇
  2010年   119篇
  2009年   115篇
  2008年   177篇
  2007年   169篇
  2006年   174篇
  2005年   119篇
  2004年   103篇
  2003年   81篇
  2002年   74篇
  2001年   41篇
  2000年   34篇
  1999年   37篇
  1998年   10篇
  1997年   11篇
  1996年   11篇
  1995年   6篇
  1994年   5篇
  1993年   7篇
  1992年   24篇
  1991年   17篇
  1990年   9篇
  1989年   28篇
  1988年   20篇
  1987年   16篇
  1986年   13篇
  1985年   16篇
  1984年   6篇
  1983年   4篇
  1982年   5篇
  1979年   2篇
  1974年   3篇
  1970年   3篇
  1969年   2篇
  1968年   2篇
  1967年   4篇
  1964年   2篇
排序方式: 共有2664条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
40 mg of isosorbide mononitrate (isosorbide-5-mononitrate, IS5MN) in conventional (Ismo 20) and sustained release formulations (Ismo Diffutab) were administered to 5 male healthy volunteers. The administration of the sustained release formulation was repeated for seven days in order to evaluate the possible occurrence of accumulation. Pharmacokinetic data showed that the sustained release formulation reached significantly lower and delayed mean peak plasma levels compared with the conventional formulation, respectively 452.8 +/- 67.8 ng/ml and 706.7 +/- 57.3 (mean +/- SE) (p less than 0.05). Peak times were 4.6 +/- 0.2 and 2.4 +/- 0.2 (p less than 0.005) h, respectively. A longer plasma half-life together with larger AUC for the sustained release formulation was also observed. The pharmacokinetic parameters of the sustained release formulation are consistent with a therapeutic usefulness and suggest further clinical evaluation.  相似文献   
5.
Chromosome investigations were carried out in 7 patients with Fanconi's anemia, type Estren-Dameshek. The frequency and types of chromosome instability found in cultured lymphocytes were in accord with those detected in individuals with classical Fanconi's anemia. The break-point distribution indicates a significant excess of breaks in chromosomes No. 1, 2, and 7 and a deficit in No. 18 and X and Y chromosomes. There was a clear clustering of breaks at certain locations in chromosomes No. 1, 2, 3, 7, 9, and 14. The location of the breaks with respect to the bands demonstrated an almost exclusive involvement of the lighter bands, regardless of the banding method used. These results suggest that most breaks take place in the interbands between the G and R bands. In all patients, chromosome instability was less frequent in direct bone marrow preparations than in lymphocyte cultures. However, cultured bone marrow cells showed a significant increase of chromosome aberrations. On the whole, the chromosome data derived from this series of patients are in agreement with those obtained in individuals with classical Fanconi's anemia and give no support to the idea of cytogenetic heterogeneity between subjects affected by these two forms of childhood aplastic anemia.  相似文献   
6.
7.
In the last few years there has been an increasing diffusion of endoscopic percutaneous trans-lumbar lithotripsy as a treatment for kidney stones. This technique requires an adequate pyelostomic approach. The authors at this purpose suggest the utilisation of the "One Stick Introducer System Set", that has been created for the biliary tree catheterism as this set is easy to use and rarely traumatic for the patient.  相似文献   
8.
Obesity and diet are associated with colorectal cancer (CRC) risk, and microbiome could mediate this risk factor. To investigate this interaction, we performed a case–control study (34 CRC cases and 32 controls) and analyzed fecal microbiota composition using 16S rRNA metabarcoding and sub-sequential shotgun analyses of genomic bacterial DNA to evaluate the role of microbiome and diet in CRC etiology, taking into account vitamin D and other risk biomarkers. Dietary habits were evaluated using a short questionnaire. Multivariate methods for data integration and mediation analysis models were used to investigate causal relationships. CRC cases were significantly more often deficient in vitamin D than controls (p = 0.04); FokI and CYP24A1 polymorphism frequency were different between cases and controls (p = 0.03 and p = 0.02, respectively). A diet poor in fatty fish and rich in carbohydrates was found to be significantly associated with CRC risk (p = 0.011). The mediation analysis confirmed the significant role of the microbiome in mediating CRC risk—increasing levels of Bifidobacteria/Escherichia genera ratio, an indicator of “healthy” intestinal microbiome, can overcome the effect of diet on CRC risk (p = 0.03). This study suggests that microbiome mediates the diet effect on CRC risk, and that vitamin D, markers of inflammation, and adipokines are other factors to consider in order to achieve a better knowledge of the whole carcinogenic process.  相似文献   
9.
Severe obesity is associated with an increased risk of admission to intensive care units and need for invasive mechanical ventilation in patients with COVID-19. The association of obesity and COVID-19 prognosis may be related to many different factors, such as chronic systemic inflammation, the predisposition to severe respiratory conditions and viral infections. The ketogenic diet is an approach that can be extremely effective in reducing body weight and visceral fat in the short term, preserving the lean mass and reducing systemic inflammation. Therefore, it is a precious preventive measure for severely obese people and may be considered as an adjuvant therapy for patients with respiratory compromise.  相似文献   
10.
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