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   7564篇
  免费   618篇
  国内免费   22篇
耳鼻咽喉   78篇
儿科学   216篇
妇产科学   165篇
基础医学   991篇
口腔科学   90篇
临床医学   906篇
内科学   1375篇
皮肤病学   156篇
神经病学   900篇
特种医学   158篇
外科学   908篇
综合类   125篇
一般理论   11篇
预防医学   822篇
眼科学   188篇
药学   562篇
中国医学   6篇
肿瘤学   547篇
  2024年   16篇
  2023年   148篇
  2022年   181篇
  2021年   418篇
  2020年   213篇
  2019年   338篇
  2018年   349篇
  2017年   230篇
  2016年   296篇
  2015年   298篇
  2014年   364篇
  2013年   420篇
  2012年   674篇
  2011年   638篇
  2010年   310篇
  2009年   278篇
  2008年   439篇
  2007年   433篇
  2006年   409篇
  2005年   350篇
  2004年   314篇
  2003年   242篇
  2002年   230篇
  2001年   58篇
  2000年   50篇
  1999年   37篇
  1998年   34篇
  1997年   26篇
  1996年   20篇
  1995年   22篇
  1994年   25篇
  1993年   21篇
  1992年   36篇
  1991年   23篇
  1990年   23篇
  1989年   15篇
  1988年   22篇
  1987年   17篇
  1986年   12篇
  1985年   17篇
  1984年   17篇
  1982年   12篇
  1981年   9篇
  1980年   14篇
  1979年   7篇
  1978年   7篇
  1975年   12篇
  1974年   7篇
  1972年   7篇
  1971年   7篇
排序方式: 共有8204条查询结果,搜索用时 15 毫秒
31.
32.
European Journal of Epidemiology - Initial results from various phase-III trials on vaccines against SARS-CoV-2 are promising. For proper translation of these results to clinical guidelines, it is...  相似文献   
33.
Down syndrome regression disorder (DSRD) is a clinical symptom cluster of acute or subacute neurocognitive regression in otherwise health persons with Down syndrome. The objective of this study was to evaluate if adverse childhood experiences (ACEs) were more prevalent in children with DSRD than those with DS alone. A survey-based, cohort-based study was performed. Caregivers of individuals with DSRD with onset of symptoms between age 10 and 30 years and DS alone were administered the ACEs questionnaire via an online REDCap survey. A total of 159 responses were collected after excluding incomplete surveys and those not meeting criteria for DSRD. Individuals with DSRD were not more likely to experience ACEs (p = 0.18, 95% confidence interval [CI]: 0.43–1.17). In those with ACEs prior to the onset of symptoms, the median time prior was 7 months (interquartile range: 5–10). Individuals with DSRD were more likely to report three or more ACEs (52, 33%) compared to those with DS alone (39, 22%) (p = 0.02, 95% CI: 1.08–2.87). Exposure to ACEs were not predictive of response to particular therapeutic interventions although those with multiple ACEs 3 months prior to the onset of symptoms was associated with lower response rates to benzodiazepines and immunotherapy (p = 0.02, 95% CI: −3.64–−1.13). This study provides preliminary data that individuals with DSRD experience ACEs at a similar rate to individuals with only DS alone, although three or more ACEs, often preceding the onset of symptoms, was more prevalent in individuals with DSRD.  相似文献   
34.
35.
This article shows that re-normalizing the interpolation kernel for a constant integral can make a significant improvement in performance of sinc interpolation methods. A comparison was performed between standard and re-normalized sinc kernels of various sizes using data from four commonly used magnetic resonance (MR) imaging sequences. Standard rotations were performed and compared with a "gold standard" data set generated by use of a large (13 x 13 x 13) sinc kernel. Measurements of systematic pixel intensity offset error and variance of generated residuals were used to estimate resultant interpolation error. Theoretical estimates of the consequent savings in computation time were compared with the measured time required for each algorithm and with the automated image registration (AIR) program. The use of a small (5 x 5 x 5) re-normalized kernel produced relative errors comparable to those in the gold standard data set, allowing saving in computation time of up to 30 times in comparison with standard sinc interpolation. This approach brings the implementation of MR volume re-slicing much closer to the demands of a clinical environment. J. Magn. Reson. Imaging 1999;10:582-588.  相似文献   
36.
In this prospective randomised study, pruritus and pain were evaluated in patients undergoing abdominal surgery during which epidural fentanyl was administered. All patients had an epidural catheter inserted at the time of surgery. Epidural fentanyl 100 micrograms was administered intra-operatively and infused at a concentration of 2 micrograms.ml-1 for 48 h postoperatively. All patients received a standard anaesthetic and, in addition, the study group had a 20 mg bolus of tenoxicam intravenously, intra-operatively. Patients receiving tenoxicam demonstrated significantly lower pruritus and pain scores at 30 min, 2, 4, 8 and 24 h postoperatively as well as reduced pethidine requirements for breakthrough pain in the first 24 h. In conclusion, tenoxicam 20 mg significantly reduces the incidence and severity of postoperative pruritus in patients who received peri-operative epidural fentanyl. In addition, it significantly reduces pain and further analgesic requirements postoperatively.  相似文献   
37.
38.
39.
Cannabidiol (CBD) is widely available and marketed as having therapeutic properties. Over-the-counter CBD is unregulated, many of the therapeutic claims lack scientific support, and controversy exists as to the safety of CBD-liver interaction. The study aims were to compare the pharmacokinetics of commercial CBD and CBD metabolites following the ingestion of five different CBD formulations, determine the influence of CBD on food induced thermogenesis, determine the influence of food on CBD pharmacokinetics, and determine the influence of CBD on markers of liver function. Fourteen males (body mass index ≥ 25 kg/m2) were studied in a placebo-controlled, randomized, crossover design. On five occasions, different CBD formulations were ingested (one per visit). On two additional occasions, CBD or placebo was ingested following a meal. CBD servings were standardized to 30 mg. Considerable pharmacokinetic variability existed between formulations; this pharmacokinetic variability transferred to several of the metabolites. CBD did not influence food induced thermogenesis but did favorably modify early insulin and triglyceride responses. Food appreciably altered the pharmacokinetics of CBD. Finally, CBD did not evoke physiologically relevant changes in markers of liver function. Collectively, these data suggest that consumers should be aware of the appreciable pharmacokinetic differences between commercial CBD formulations, CBD is unlikely to influence the caloric cost of eating but may prove to be of some benefit to initial metabolic responses, consuming CBD with food alters the dynamics of CBD metabolism and increases systemic availability, and low-dose CBD probably does not represent a risk to normal liver function.  相似文献   
40.
We tested swab specimens from pets in households in Ontario, Canada, with human COVID-19 cases by quantitative PCR for SARS-CoV-2 and surveyed pet owners for risk factors associated with infection and seropositivity. We tested serum samples for spike protein IgG and IgM in household pets and also in animals from shelters and low-cost neuter clinics. Among household pets, 2% (1/49) of swab specimens from dogs and 7.7% (5/65) from cats were PCR positive, but 41% of dog serum samples and 52% of cat serum samples were positive for SARS-CoV-2 IgG or IgM. The likelihood of SARS-CoV-2 seropositivity in pet samples was higher for cats but not dogs that slept on owners’ beds and for dogs and cats that contracted a new illness. Seropositivity in neuter-clinic samples was 16% (35/221); in shelter samples, 9.3% (7/75). Our findings indicate a high likelihood for pets in households of humans with COVID-19 to seroconvert and become ill.  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