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   2758篇
  免费   255篇
  国内免费   10篇
耳鼻咽喉   17篇
儿科学   60篇
妇产科学   35篇
基础医学   380篇
口腔科学   91篇
临床医学   323篇
内科学   597篇
皮肤病学   18篇
神经病学   285篇
特种医学   206篇
外科学   305篇
综合类   73篇
预防医学   250篇
眼科学   17篇
药学   166篇
肿瘤学   200篇
  2022年   24篇
  2021年   39篇
  2020年   35篇
  2019年   32篇
  2018年   42篇
  2017年   32篇
  2016年   41篇
  2015年   42篇
  2014年   44篇
  2013年   95篇
  2012年   115篇
  2011年   124篇
  2010年   73篇
  2009年   76篇
  2008年   111篇
  2007年   101篇
  2006年   105篇
  2005年   97篇
  2004年   105篇
  2003年   103篇
  2002年   94篇
  2001年   77篇
  2000年   80篇
  1999年   92篇
  1998年   61篇
  1997年   59篇
  1996年   54篇
  1995年   48篇
  1994年   46篇
  1993年   38篇
  1992年   68篇
  1991年   65篇
  1990年   59篇
  1989年   60篇
  1988年   49篇
  1987年   53篇
  1986年   57篇
  1985年   65篇
  1984年   28篇
  1983年   26篇
  1981年   21篇
  1979年   26篇
  1976年   20篇
  1975年   20篇
  1974年   26篇
  1973年   21篇
  1972年   24篇
  1971年   21篇
  1968年   20篇
  1966年   20篇
排序方式: 共有3023条查询结果,搜索用时 15 毫秒
91.

Aims/hypothesis  

An increase in the production of reactive oxygen species is commonly thought to contribute to the development of diabetic cardiomyopathy. This study aimed to assess whether administration of the antioxidant coenzyme Q10 would protect the diabetic heart against dysfunction and remodelling, using the db/db mouse model of type 2 diabetes. Furthermore, we aimed to compare the efficacy of coenzyme Q10 to that of the ACE inhibitor ramipril.  相似文献   
92.
The objectives of the study were to determine associations between single nucleotide polymorphisms (SNPs) of the vitamin D receptor (VDR) gene and insulin resistance and the effects of these SNPs on changes in insulin sensitivity in response to vitamin D supplementation. The research described here was an extension of the Surya study. Genotyping of the Cdx-2, FokI, BsmI, ApaI, and TaqI SNPs was carried out on 239 South Asian women in New Zealand using polymerase chain reaction-based techniques. Associations of these genotypes and 3' end haplotypes with insulin resistance were determined using multiple regression analysis. Associations between SNP genotypes and responses in insulin sensitivity to vitamin D supplementation (4000 IU vitamin D(3) per day) were also determined for a subset (81) of these women. BsmI BB, ApaI AA, and TaqI tt genotypes were significantly associated with lower insulin resistance compared with BsmI bb, ApaI aa, and TaqI TT, respectively, in the cohort of 239 women. Furthermore, homozygosity of the haplotypes baT and BAt was associated with higher and lower insulin resistance, respectively, compared with no copies of their respective alleles. Of the 81 subjects who were supplemented with vitamin D, women with the FokI Ff genotype showed a significantly greater improvement in insulin sensitivity (increase of 29.4 [2.9, 38.1]) compared with women with the FokI FF genotype (increase of 2.3 [-11.5, 10.1]). This study has highlighted the association of vitamin D responsiveness and insulin resistance with VDR gene polymorphisms. This is the first study to determine associations between all three. Genotyping of the VDR gene may provide a predictive measure for insulin resistance in response to vitamin D intervention.  相似文献   
93.
Tobacco smoking is a risk factor for atrial fibrillation (AF), but little is known about the impact of smoking in patients with AF. Of the 4060 patients with recurrent AF in the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial, 496 (12%) reported having smoked during the past two years. Propensity scores for smoking were estimated for each of the 4060 patients using a multivariable logistic regression model and were used to assemble a matched cohort of 487 pairs of smokers and nonsmokers, who were balanced on 46 baseline characteristics. Cox and logistic regression models were used to estimate the associations of smoking with all-cause mortality and all-cause hospitalization, respectively, during over 5 years of follow-up. Matched participants had a mean age of 70 ± 9 years (± S.D.), 39% were women, and 11% were non-white. All-cause mortality occurred in 21% and 16% of matched smokers and nonsmokers, respectively (when smokers were compared with nonsmokers, hazard ratio=HR=1.35; 95% confidence interval=95%CI=1.01-1.81; p=0.046). Unadjusted, multivariable-adjusted and propensity-adjusted HR (95% CI) for all-cause mortality associated with smoking in the pre-match cohort were: 1.40 (1.13-1.72; p=0.002), 1.45 (1.16-1.81; p=0.001), and 1.39 (1.12-1.74; p=0.003), respectively. Smoking had no association with all-cause hospitalization (when smokers were compared with nonsmokers, odds ratio=OR=1.21; 95%CI=0.94-1.57, p=0.146). Among patients with AF, a recent history of smoking was associated with an increased risk of all-cause mortality, but had no association with all-cause hospitalization.  相似文献   
94.
The present study used a known-groups design to determine the classification accuracy of 10 MMPI-2 validity scales and indicators in the detection of cognitive malingering in traumatic brain injury. Participants were 259 traumatic brain injury and 133 general clinical patients seen for neuropsychological evaluation. The TBI patients were subdivided into groups based on a comprehensive examination of effort following Slick, Sherman, and Iverson's (1999 Slick , D. J. , Sherman , E. M. S. , & Iverson , G. L. ( 1999 ). Diagnostic criteria for malingering neurocognitive dysfunction: Proposed standards for clinical practice and research . The Clinical Neuropsychologist , 13 , 545561 . [INFOTRIEVE] [CSA] [Taylor & Francis Online], [Web of Science ®] [Google Scholar]) criteria. More extreme scores demonstrated excellent specificity; often impressive sensitivity was seen even while maintaining a low false positive error rate. Specificity was good even in stroke, memory disorder, and psychiatric patients without incentive. The results of this study are presented in frequency tables that can be easily referenced in clinical practice.  相似文献   
95.
We isolated and characterized a total of 19 microsatellite loci from the North American porcupine, Erethizon dorsatum. Loci were screened in 22 individuals from St. Lawrence and Franklin Counties in northern New York State. The number of alleles per locus ranged from 4 to 14, observed heterozygosity ranged from 0.316 to 1.000, and the probability of identity values ranged from 0.028 to 0.243. These new loci will provide tools for examination of the effects of habitat fragmentation, for instance by roads and other infrastructure, on gene flow and population subdivision in this species.  相似文献   
96.
手术是脉管性病变治疗的一种手段,其主要作用是与放射治疗及各种药物治疗协同作用。对于血管瘤患者,手术仅限于普萘洛尔治疗无效,出现并发症及位于眼部的病变。整形手术可使血管瘤消退后遗留的面部畸形得到改善。对于一些范围较小的局灶性病变,手术往往可以取得满意的效果;对于巨大、多发的血管瘤,手术治疗往往作用有限,常常为减瘤术。手术患者一般在术前均经过栓塞硬化治疗,这样可以大大减少术中出血。手术无法治愈脉管性疾病,是一种辅助  相似文献   
97.

Purpose

Pulmonary edema (PE) is associated with fluid accumulation in the lungs. Device-based impedance measurements have been used to detect fluid overload prior to hospitalization. However, studies have reported a high false positive rate (FPR). The objective of this study was to develop and test a new multivector impedance-based algorithm that reliably tracks PE clinical events.

Methods

We enrolled patients with implanted CRT-Ds in 23 US centers within 2 weeks of device implant. Six-vector impedance data was collected automatically by the CRT-Ds every 30 min during emergency department visits/hospitalizations and every 2 h at all other times. Detection algorithms for cardiac resynchronization therapy defibrillator (CRT-D) and implantable cardiac defibrillator (ICD) devices were developed using those impedance vectors that would be available in corresponding devices and retrospectively evaluated.

Results

There were 75 patients (69 % male), mean age 66?±?12 years, with a LVEF of 23?±?6 % and QRS of 149?±?25 ms. Twenty-one major clinical events occurred over 8.2?±?2.6 months of follow-up time. CRT-D vector combinations resulted in a sensitivity of 71.4 % (95 % confidence interval 47.8–88.7) and a FPR of 0.56 (0.30–0.94) false positives per patient-year (FPs/pt-yr); ICD vector combinations resulted in a sensitivity of 61.9 % (38.4–81.9) and a FPR of 0.63 (0.36–0.90) FPs/pt-yr. In comparison, the single-vector RVCoil-Can implementation of this algorithm resulted in a sensitivity of 57.1 % (34.0–78.2) and a FPR of 0.74 (0.44–1.12) FPs/pt-yr.

Conclusions

This multivector impedance algorithm was effective in tracking PE clinical events in this patient population. Additional studies are needed to prospectively evaluate the performance of this algorithm in a larger population.  相似文献   
98.
Aim: To obtain experts' estimates of the number of non‐medical care hours required by older Singaporeans at different stages of ageing‐related dementia, with low or high behavioural features. Methods: Experts on dementia in Singapore attended one of two meetings where they provided estimates of the number of care hours required for individuals at mild, moderate and severe levels of dementia with either low or high behavioural features. The experts were shown the collated responses, given an opportunity to discuss as a group, and then polled again. Results: The estimated mean care hours varied by dementia severity and the level of behavioural features. There was no interaction between dementia severity and behavioural features. Conclusion: Estimated care hours needed by individuals with dementia is independently influenced by severity of dementia and behavioural features. These estimates may be useful for policy‐makers in projecting the impact of caregiving.  相似文献   
99.
100.
Pain, swelling, trismus, and alveolar osteitis often occur after removal of impacted third molar teeth. To minimize these complications a number of mucoperiosteal flap designs have been advocated, but, to date, a pedicle flap design has not been evaluated. In a randomized prospective split mouth study, 52 participants had bilateral symmetrically impacted mandibular third molars removed over two sessions. A buccal envelope or pedicle flap was randomly assigned to the left or right third molar site. Pre-and postoperative pain and swelling were recorded using a standardized visual analogue scale, trismus was measured as the maximum inter-incisal opening distance in millimetres and dry socket was assessed clinically. Greater continuous pain, pain on maximum opening, and oro-facial swelling were recorded with the pedicle flap design. Continuous pain resolved significantly faster with this flap design (p<0.05). Trismus was similar for both flap designs (p>0.05). Five cases of alveolar osteitis occurred with the envelope flap whilst no cases developed with the pedicle flap, but the incidence was too small for statistical analysis. The pedicle flap improved some aspects of postoperative pain experience and reduced the incidence of alveolar osteitis, but further investigation with a larger sample size is required to evaluate its significance.  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