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   2871330篇
  免费   223536篇
  国内免费   5248篇
耳鼻咽喉   41130篇
儿科学   89818篇
妇产科学   75110篇
基础医学   413980篇
口腔科学   82106篇
临床医学   262272篇
内科学   555638篇
皮肤病学   59468篇
神经病学   233335篇
特种医学   113199篇
外国民族医学   946篇
外科学   432621篇
综合类   67051篇
现状与发展   3篇
一般理论   1101篇
预防医学   228430篇
眼科学   67616篇
药学   216605篇
  7篇
中国医学   6184篇
肿瘤学   153494篇
  2018年   29525篇
  2017年   22782篇
  2016年   25205篇
  2015年   28387篇
  2014年   40444篇
  2013年   61484篇
  2012年   82715篇
  2011年   87421篇
  2010年   51495篇
  2009年   49034篇
  2008年   82574篇
  2007年   88266篇
  2006年   89259篇
  2005年   86310篇
  2004年   83438篇
  2003年   80239篇
  2002年   79115篇
  2001年   134890篇
  2000年   139173篇
  1999年   117237篇
  1998年   33266篇
  1997年   29966篇
  1996年   29937篇
  1995年   28794篇
  1994年   26985篇
  1993年   25149篇
  1992年   94360篇
  1991年   91701篇
  1990年   88851篇
  1989年   85905篇
  1988年   79653篇
  1987年   78267篇
  1986年   74205篇
  1985年   70552篇
  1984年   53197篇
  1983年   45241篇
  1982年   27032篇
  1981年   24122篇
  1979年   49755篇
  1978年   35014篇
  1977年   29470篇
  1976年   27907篇
  1975年   29613篇
  1974年   36233篇
  1973年   34353篇
  1972年   32260篇
  1971年   29759篇
  1970年   28159篇
  1969年   26168篇
  1968年   23819篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Obtaining accurate assessment data from adolescents in treatment aids clinical decision making and facilitates more accurate outcome evaluations. However, findings could be biased due to underreported substance use and mental health symptoms. This article compares self-reports of youth in non-White matched client–assessor dyads and those in nonmatched dyads. There were no differences on self-reported substance use, but matched youth reported significantly fewer attention deficit/hyperactivity disorder symptoms versus the comparison group. One possible reason for these findings is the effect of in-group stereotype threat. Future studies should examine the potential effect that in-group stereotyping and perceived racism have on the therapeutic relationship.  相似文献   
92.
93.
94.
This study explored the relationship between active mediation, exposure to Daniel Tiger’s Neighborhood, and key indicators of preschoolers’ social and emotional development. One hundred and twenty-seven children aged 2–6 either watched or did not watch 10 episodes of Daniel Tiger’s Neighborhood over a two-week period. Results revealed that preschoolers who watched the program exhibited higher levels of empathy, self-efficacy, and emotion recognition when their regular TV-watching experiences are frequently accompanied by active mediation. This was especially true for younger preschoolers and preschoolers from low-income families. Implications for policy-makers, parents, producers of prosocial programming, and educators are discussed.  相似文献   
95.
96.
On 8 April 2014, a US jury ordered Takeda and Eli Lilly to pay $9 bn in punitive damages after finding that they had concealed the cancer risks associated with pioglitazone. By contrast, on 28 August 2014, the long‐awaited outcome of the 10‐year Kaiser Permanente Northern California study was announced. That study was specifically designed to investigate whether patients exposed to pioglitazone were at an increased risk of bladder cancer and found no association; thus, at last, the controversial issue has been resolved. A review, in retrospect, of the story of the proposed link between pioglitazone and bladder cancer reveals flaws at every stage. In 2012, a BMJ editorial, in keeping with some other contemporary reports, stated ‘it can confidently be assumed that pioglitazone increases the risk of bladder cancer’. Examination of the information which led to such a statement shows that: 1) the pre‐clinical findings of bladder cancer in male rats is not indicative of human risk; 2) there is no association between bladder cancer and pioglitazone in randomized controlled trials, once cases that could not plausibly be related to treatment are removed; and 3) the observational studies that have suggested a link have over‐extrapolated from the data: pioglitazone‐treated patients had more risk factors for bladder cancer than those not treated with pioglitazone. Meanwhile careful study of randomized controlled trials shows evidence of cardiovascular benefit from pioglitazone in Type 2 diabetes, a condition which results, more than anything, in premature cardiovascular death and morbidity.  相似文献   
97.
98.
99.

Background

Obesity is a risk factor for acetabular component malposition when total hip arthroplasty is performed with manual techniques. The utility of imageless navigation in obese patients remains unknown. This study compared the accuracy and precision of imageless navigation for component orientation between obese and nonobese patients.

Methods

A total of 459 total hip arthroplasties performed for osteoarthritis using imageless navigation were reviewed from a single surgeon’s institutional review board–approved database. Einzel-Bild-Roentgen Analyse determined component orientation on 6-week postoperative anteroposterior radiographs. Mean orientation error (accuracy) and precision were compared between obese (body mass index ≥ 30 kg/m2) and nonobese patients. Regression analysis evaluated the influence of obesity on component position.

Results

The difference in mean inclination and anteversion between obese and nonobese groups was 1.1° (43.0° ± 3.5°; range, 35.8°-57.8° vs 41.9° ± 4.4°; range, 33.0°-57.1° and 24.9° ± 6.3°; range, 14.2°-44.3° vs 23.8° ± 6.6°; range, 7.0°-38.6°, respectively). Inclination precision was better for nonobese patients. No difference in inclination accuracy or anteversion accuracy or precision was detected between groups. And 83% of components were placed within the target range. There was no relationship between obesity (dichotomized) and component placement outside the target ranges for inclination, anteversion, or both. As a continuous variable, increased body mass index correlated with higher odds of inclination outside the target zone (odds ratio, 1.06; P = .001).

Conclusion

Using imageless navigation, inclination orientation was less precise for obese patients, but the observed difference is likely not clinically relevant. Accurate superficial registration of landmarks in obese patients is achievable, and the use of imageless navigation similarly improves acetabular component positioning in obese and nonobese patients.

Level of Evidence

Therapeutic Level IV.  相似文献   
100.

Objective

Low psoas muscle area is shown to be an indicator for worse postoperative outcome in patients undergoing vascular surgical. Additionally, it has been associated with longer durations of hospital stay in patients with cancer who undergo surgery and subsequently greater health care costs in Europe and the United States. We sought to evaluate this effect on hospital expenditure for patients undergoing vascular repair in a health care system with universal access.

Methods

Skeletal muscle mass was assessed on preoperative abdominal computed tomography scans of patients undergoing open aortic aneurysm repair in a retrospective fashion. The skeletal muscle index (SMI) was used to define low muscle mass. Health care costs were obtained for all patients and the relationship between a low SMI and higher costs was explored using linear regression and cross-sectional analysis.

Results

We included 156 patients (81.5% male) with a median age of 72 years undergoing elective surgery for infrarenal abdominal aortic aneurysm in this analysis. The median SMI for patients with low skeletal muscle mass was 53.21 cm2/kg and for patients without, 70.07 cm2/kg. Hospital duration of stay was 2 days longer in patients with low skeletal muscle mass as compared with patients with normal (14 days vs 11 days; P = .001), as was duration of intensive care stay (3 days vs 1 day; P = .01). The median overall hospital costs were €10,460 higher for patients with a low SMI as compared with patients with a normal physical constitution (€53,739 [interquartile range, €45,007-€62,471] vs €43,279 [interquartile range, €39,509-€47,049]; P = .001). After confounder adjustment, a low SMI was associated with a 14.68% cost increase in overall hospital costs, for a cost increase of €6521.

Conclusions

Low skeletal muscle mass is independently associated with higher hospital as well as intensive care costs in patients undergoing elective aortic aneurysm repair. Strategies to reduce this risk factor are warranted for these patients.  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