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   1691篇
  免费   171篇
耳鼻咽喉   5篇
儿科学   54篇
妇产科学   77篇
基础医学   292篇
口腔科学   6篇
临床医学   167篇
内科学   389篇
皮肤病学   21篇
神经病学   188篇
特种医学   64篇
外科学   217篇
综合类   29篇
一般理论   1篇
预防医学   140篇
眼科学   10篇
药学   109篇
中国医学   1篇
肿瘤学   92篇
  2022年   12篇
  2021年   23篇
  2020年   16篇
  2019年   32篇
  2018年   36篇
  2017年   19篇
  2016年   26篇
  2015年   37篇
  2014年   38篇
  2013年   65篇
  2012年   98篇
  2011年   85篇
  2010年   50篇
  2009年   51篇
  2008年   78篇
  2007年   81篇
  2006年   80篇
  2005年   72篇
  2004年   79篇
  2003年   60篇
  2002年   61篇
  2001年   49篇
  2000年   46篇
  1999年   42篇
  1998年   16篇
  1997年   14篇
  1996年   15篇
  1994年   16篇
  1993年   15篇
  1992年   30篇
  1991年   32篇
  1990年   35篇
  1989年   30篇
  1988年   24篇
  1987年   30篇
  1986年   24篇
  1985年   29篇
  1984年   24篇
  1983年   19篇
  1982年   13篇
  1981年   17篇
  1980年   12篇
  1979年   18篇
  1978年   16篇
  1977年   13篇
  1976年   13篇
  1975年   19篇
  1973年   15篇
  1971年   12篇
  1970年   11篇
排序方式: 共有1862条查询结果,搜索用时 15 毫秒
51.
52.
53.
Current knowledge about cultural differences in the trauma autobiographical memory is limited. Such a limitation reduces the body of empirical evidence that can be drawn upon to inform decisions about asylum. The objective of this study was to explore the impact of cultural differences in self-construal on the specificity of autobiographical memories. Research participants from independent and interdependent cultures were asked to provide autobiographical memories of everyday events, trauma events and self-defining memories. Those from independent cultures consistently provided more specific autobiographical memories than those from interdependent cultures. The findings indicate that specificity has an essential role in enhancing the dominant self-focus and needs to be considered when deeming a memory as credible.  相似文献   
54.

Background

Surges in heart rate (HR) and blood pressure (BP) at apnea termination contribute to the hypertension seen in obstructive sleep apnea (OSA). Because childhood OSA prevalence peaks in the preschool years, we aimed to characterize the cardiovascular response to obstructive events in preschool-aged children.

Methods

Clinically referred children aged 3–5 years were grouped by obstructive apnea–hypopnea index (OAHI) into the following: primary snoring (PS) (OAHI ? 1 event/h [n = 21]), mild OSA (OAHI > 1– ? 5 [n = 32]), and moderate to severe (MS) OSA (OAHI > 5 [n = 28]). Beat-to-beat pulse transit time (PTT), an inverse continuous indicator of BP changes, and HR were averaged during the two halves (early and late) and during the peak after (post) each obstructive event and were expressed as percentage change from late- to post-event.

Results

We analyzed 422 events consisting of 55 apneas and 367 hypopneas. A significant post-event increase in HR and fall in PTT occurred in all severity groups (P < .05 for all). A greater response was associated with OSA, nonrapid eye movement sleep (NREM), cortical arousal, hypopneas, and oxygen desaturation (P < .05 for all).

Conclusions

Obstructive events elicit acute cardiovascular changes in preschool children. Such circulatory perturbations have been implicated in the development of hypertension, and our findings complement previous studies to suggest a cumulative impact of snoring on the cardiovascular system from childhood into adulthood.  相似文献   
55.
The conventional model that bisphosphonates bind to the bone surface and inhibit mature osteoclasts does not convincingly explain the prolonged duration of action of zoledronate. We hypothesized that zoledronate on the bone surface adjacent to marrow cells impairs osteoclastogenesis, contributing to sustained inhibition of resorption. In this case, numbers of circulating preosteoclasts may be reduced after zoledronate treatment. This study assessed this possibility in subjects from a clinical trial. Twenty-two osteopenic women participating in a randomized, controlled trial comparing zoledronate 5 mg with placebo were recruited, 18 months after administration of study drug. Peripheral blood mononuclear cells were analyzed for the presence of osteoclast precursors using flow cytometry for preosteoclast markers and the ability to form osteoclast-like cells in culture with RANKL and M-CSF. There was no difference in the percentage of CD14+/CD11b+ cells in peripheral blood between the two groups. The numbers of TRAP+ multinucleated cells in cultures in the absence of RANKL and M-CSF were very low in both groups, but a significantly higher number of these cells was observed in the zoledronate group compared with the placebo group (p = 0.01). The number of TRAP+ multinucleated cells and resorption pits following culture with RANKL and M-CSF did not differ between the two groups. Serum P1NP was reduced 53 % at 18 months in the zoledronate group but unchanged in the placebo group. These results do not support the hypothesis that the inhibitory action of zoledronate contributes to its prolonged action on preosteoclasts within bone marrow.  相似文献   
56.
Recent preclinical studies suggest that osteoblasts are able to induce testosterone production by the testis, a process mediated by osteocalcin. Bisphosphonates substantially reduce osteocalcin levels. If osteocalcin is an important regulator of testosterone levels in adult men, it would be expected that the substantial reductions in osteocalcin induced by zoledronate would impact negatively on testosterone levels. Previously, we carried out a 2-year randomized, controlled trial of annual 4 mg zoledronate in 43 HIV-infected men. To explore the relationship between osteocalcin and testosterone further, we measured serum testosterone at baseline, 3 months, and 2 years; luteinizing hormone at 3 months and 2 years; and total osteocalcin at 2 years in 28 trial participants with available blood samples. At 2 years, total osteocalcin was 39 % lower in the zoledronate group than the placebo group (zoledronate mean 10.1 [SD 3.0] μg/L, placebo 16.5 [SD 4.9] μg/L, P = 0.003). Despite these substantial differences in osteocalcin levels, testosterone levels did not change over time in either group and there were no between-group differences over time, P = 0.4 (mean change at 2 years [adjusted for baseline levels] in zoledronate group ?0.4 nmol/L, 95 % CI ?2.5 to 1.6; placebo group 0.4 nmol/L, 95 % CI ?1.6 to 2.5). Luteinizing hormone was within the normal range and did not differ between the groups at either 3 months or 2 years. Thus, the absence of a change in testosterone despite a substantial reduction in osteocalcin following zoledronate treatment argues against a biologically significant role for osteocalcin in the regulation of testosterone in adult men. This provides reassurance that men receiving potent antiresorptive drugs are not at risk of iatrogenic hypogonadism.  相似文献   
57.
58.
Child Psychiatry & Human Development - Little is known about the long-term prognosis of children with pediatric acute-onset neuropsychiatric syndrome (PANS). Out of the 46 eligible patients...  相似文献   
59.
60.
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