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   1037篇
  免费   88篇
  国内免费   1篇
耳鼻咽喉   8篇
儿科学   25篇
妇产科学   25篇
基础医学   99篇
口腔科学   4篇
临床医学   81篇
内科学   254篇
皮肤病学   3篇
神经病学   76篇
特种医学   27篇
外科学   186篇
综合类   31篇
一般理论   1篇
预防医学   173篇
眼科学   11篇
药学   64篇
中国医学   5篇
肿瘤学   53篇
  2023年   6篇
  2022年   5篇
  2021年   25篇
  2020年   11篇
  2019年   18篇
  2018年   24篇
  2017年   14篇
  2016年   18篇
  2015年   24篇
  2014年   32篇
  2013年   43篇
  2012年   72篇
  2011年   75篇
  2010年   38篇
  2009年   33篇
  2008年   58篇
  2007年   67篇
  2006年   62篇
  2005年   49篇
  2004年   51篇
  2003年   39篇
  2002年   38篇
  2001年   32篇
  2000年   51篇
  1999年   23篇
  1998年   11篇
  1997年   15篇
  1996年   9篇
  1995年   6篇
  1993年   3篇
  1992年   12篇
  1991年   15篇
  1990年   16篇
  1989年   16篇
  1988年   14篇
  1987年   11篇
  1986年   11篇
  1985年   4篇
  1984年   18篇
  1983年   9篇
  1982年   7篇
  1981年   5篇
  1980年   2篇
  1979年   3篇
  1978年   4篇
  1974年   4篇
  1973年   2篇
  1972年   5篇
  1971年   5篇
  1968年   2篇
排序方式: 共有1126条查询结果,搜索用时 15 毫秒
1.
Dosage form is a mean used for the delivery of drug to a living body. In order to get the desired effect the drug should be delivered to its site of action at such rate and concentration to achieve the maximum therapeutic effect and minimum adverse effect. Since oral route is still widely accepted route but having a common drawback of difficulty in swallowing of tablets and capsules. Therefore a lot of research has been done on novel drug delivery systems. This review is about oral dispersible tablets a novel approach in drug delivery systems that are now a day''s more focused in formulation world, and laid a new path that, helped the patients to build their compliance level with the therapy, also reduced the cost and ease the administration especially in case of pediatrics and geriatrics. Quick absorption, rapid onset of action and reduction in drug loss properties are the basic advantages of this dosage form.  相似文献   
2.
Prevalence of osteoporosis is more than 50% in older adults, yet current clinical methods for diagnosis that rely on areal bone mineral density (aBMD) fail to detect most individuals who have a fragility fracture. Bone fragility can manifest in different forms, and a “one-size-fits-all” approach to diagnosis and management of osteoporosis may not be suitable. High-resolution peripheral quantitative computed tomography (HR-pQCT) provides additive information by capturing information about volumetric density and microarchitecture, but interpretation is challenging because of the complex interactions between the numerous properties measured. In this study, we propose that there are common combinations of bone properties, referred to as phenotypes, that are predisposed to different levels of fracture risk. Using HR-pQCT data from a multinational cohort (n = 5873, 71% female) between 40 and 96 years of age, we employed fuzzy c-means clustering, an unsupervised machine-learning method, to identify phenotypes of bone microarchitecture. Three clusters were identified, and using partial correlation analysis of HR-pQCT parameters, we characterized the clusters as low density, low volume, and healthy bone phenotypes. Most males were associated with the healthy bone phenotype, whereas females were more often associated with the low volume or low density bone phenotypes. Each phenotype had a significantly different cumulative hazard of major osteoporotic fracture (MOF) and of any incident osteoporotic fracture (p < 0.05). After adjustment for covariates (cohort, sex, and age), the low density followed by the low volume phenotype had the highest association with MOF (hazard ratio = 2.96 and 2.35, respectively), and significant associations were maintained when additionally adjusted for femoral neck aBMD (hazard ratio = 1.69 and 1.90, respectively). Further, within each phenotype, different imaging biomarkers of fracture were identified. These findings suggest that osteoporotic fracture risk is associated with bone phenotypes that capture key features of bone deterioration that are not distinguishable by aBMD. © 2021 American Society for Bone and Mineral Research (ASBMR).  相似文献   
3.
4.
5.
The case of a 62-year-old man with benign schwannoma associated with a giant polyp of the esophagus is presented. His initial symptom was dysphagia. The polyp was removed through cervical esophagotomy. He had no recurrence of symptoms 5 years after this procedure. Pathologic examination showed a rare histology.  相似文献   
6.
Pyrazinamide-monoresistant Mycobacterium tuberculosis in the United States   总被引:2,自引:0,他引:2  
Mycobacterium bovis is naturally resistant to the antituberculosis drug pyrazinamide (PZA). To determine whether all Mycobacterium tuberculosis complex isolates demonstrating PZA monoresistance were truly M. bovis, we examined the phenotype and genotype of isolates reported as PZA monoresistant in five counties in California from January 1996 through June 1999. Isolates reported by local laboratories to be PZA monoresistant were sent to the state reference laboratory for repeat susceptibility testing using the BACTEC radiometric method and to the Centers for Disease Control and Prevention for pncA sequencing and PCR-restriction fragment length polymorphism (RFLP) analysis of the oxyR gene. Of 1,916 isolates, 14 were reported as PZA monoresistant and 11 were available for retesting. On repeat testing, 6 of the 11 isolates were identified as PZA-susceptible M. tuberculosis, 1 was identified as PZA-monoresistant M. bovis, and 1 was identified as M. bovis BCG. The three remaining isolates were identified as PZA-monoresistant M. tuberculosis. Sequencing of the pncA and oxyR genes genotypically confirmed the two M. bovis and the six susceptible M. tuberculosis species. Each of the three PZA-monoresistant M. tuberculosis isolates had different, previously unreported, pncA gene mutations: a 24-bp deletion in frame after codon 88, a base substitution at codon 104 (Ser104Cys), and a base substitution at codon 90 (Ile90Ser). This study demonstrates that PZA monoresistance is not an absolute marker of M. bovis species but may also occur in M. tuberculosis, associated with a number of different mutational events in the pncA gene. It is the first report of PZA-monoresistant M. tuberculosis in the United States.  相似文献   
7.
This research examined whether body dissatisfaction prospectively predicted depressive mood and low self-esteem in adolescent girls and boys 5 years later. Participants were early-adolescent girls (n = 440, Time 1 M age = 12.7 years) and boys (n = 366, Time 1 M age = 12.8 years) and midadolescent girls (n = 946, Time 1 M age = 15.8 years) and boys (n = 764, Time 1 M age = 15.9 years). After controlling for Time 1 of the relevant dependent variable, ethnicity, socioeconomic status, and body mass index, Time 1 body dissatisfaction was a unique predictor of Time 2 depressive mood and low self-esteem in early-adolescent girls (depressive mood: F = 4.80, p < .05; self-esteem: F = 9.64, p < .01) and midadolescent boys (depressive mood: F = 12.27, p < .001; self-esteem: F = 9.38, p < .01) but not in early-adolescent boys or midadolescent girls. These findings are consistent with the hypothesis that body dissatisfaction is a risk factor for depressive mood and low self-esteem in both girls and boys but in different phases of adolescence.  相似文献   
8.
9.
To assess the effect of smoking on bone mineral density (BMD) at different life stages, to examine whether the effect of smoking differs between men and women, and to discover whether its effect in women differs according to history of estrogen use, a cohort study was carried out with single cross-section measurement of BMD by single and dual photon absorptiometry. The setting was the Framingham Study, a population-based cohort study with over 40 years prospectively collected data on smoking. Subjects (n=1164) consisted of cohort members participating in the 20th biennial Framingham examination (1988–1989). The measurements included in the study were BMD measured at the hip, spine and radius, smoking history ascertained at all Framingham Study examinations since 1948, and other factors affecting BMD (age, weight, estrogen use, caffeine use, alcohol use and physical activity). Neither current smoking, recent (last 10 years) smoking, nor early adulthood smoking resulted in significantly lower BMD at any skeletal site among women who had not taken estrogen. Among women who had taken estrogen, BMD at most sites was lower among current or recent smokers, although the small numbers of smokers made it difficult to find significant differences at all skeletal sites. Among men, a consistently lower BMD at all skeletal sites was observed for smokers regardless of when in their life they smoked (4–15.3% lower), although the effect of smoking during early adulthood was of a lesser magnitude (4–8% lower). Former male smokers who had quit <10 years ago had lower BMD than men who had quit 10 years ago. In conclusion, in women who had used estrogen, BMD was lower in current or recent smokers than it was in non-smokers. In men, smoking at any stage of life had adverse effects on the skeleton that was independent of weight, alcohol or caffeine use, implying other mechanisms for smoking's effect on bone.  相似文献   
10.
We report a difference in the response of serum homovanillic acid (HVA) and in the performance of some psychological tasks before and after the administration of testosterone enanthate (TE, 100 or 300 mg/wk) or nandrolone decanoate (ND, 100 or 300 mg/wk) for 6 wk to healthy men. Serum HVA was significantly increased in both the low- and high-dose ND groups, from 8.4 +/- 1.0 and 8.7 +/- 0.5 pmol/ml (mean +/- SE) to 11.6 +/- 1.7 and 10.7 +/- 1.1 pmol/ml respectively. No significant changes in HVA were observed for the groups administered TE, nor in 5-HIAA for any of the groups. The influence of ND on the dopaminergic system, which is reflected in increased serum HVA, appears to be independent from the psychological effects which were produced by both androgens. The only change in psychomotor test performance was an improvement in the first trial of a pegboard task. All subjects except those receiving ND (100 mg/wk) were significantly more optimistic in the prediction of their own performance for all nondominant hand tasks (pegboard and finger tapping). The "hostility" and "resentment and aggression" subscales of the MMPI increased significantly in all groups, more so in the high-dose groups.  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