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   3559篇
  免费   285篇
  国内免费   4篇
耳鼻咽喉   25篇
儿科学   101篇
妇产科学   88篇
基础医学   577篇
口腔科学   74篇
临床医学   481篇
内科学   599篇
皮肤病学   41篇
神经病学   323篇
特种医学   149篇
外科学   436篇
综合类   31篇
预防医学   398篇
眼科学   89篇
药学   217篇
中国医学   12篇
肿瘤学   207篇
  2022年   32篇
  2021年   80篇
  2020年   41篇
  2019年   65篇
  2018年   84篇
  2017年   67篇
  2016年   55篇
  2015年   74篇
  2014年   110篇
  2013年   138篇
  2012年   173篇
  2011年   167篇
  2010年   94篇
  2009年   94篇
  2008年   159篇
  2007年   163篇
  2006年   127篇
  2005年   126篇
  2004年   142篇
  2003年   136篇
  2002年   138篇
  2001年   118篇
  2000年   102篇
  1999年   86篇
  1998年   41篇
  1997年   46篇
  1996年   54篇
  1995年   37篇
  1994年   25篇
  1993年   32篇
  1992年   69篇
  1991年   77篇
  1990年   76篇
  1989年   78篇
  1988年   53篇
  1987年   59篇
  1986年   56篇
  1985年   51篇
  1984年   38篇
  1983年   39篇
  1982年   35篇
  1981年   23篇
  1980年   36篇
  1979年   46篇
  1978年   34篇
  1977年   23篇
  1976年   32篇
  1974年   28篇
  1973年   25篇
  1972年   18篇
排序方式: 共有3848条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
Several million American children are currently unsupervised during the hours between school and parents' leaving for and/or return from the workplace. Many families would prefer other arrangements, but cost or availability factors present insurmountable barriers. Although growing, the public response continues to fall far short of the need; in the meantime, private entrepreneurs are moving to fill the gaps in available services. But if these programs for school-aged children are to serve functions other than the aggrandizement of their sponsors, they must be focused on the real needs that exist among real American children. Among the real children in need of care are those who are impoverished, unsupervised, unfit physically, unprepared for the demands of school and workplace, hurried into premature adulthood, and/or disconnected from the social worlds around them. Professional child and youth care workers with experience in day care and residential settings have the preparation needed to take leadership roles in creating developmentally appropriate, effective programs to meet the emerging demands for school-age child care and to weave them into a fabric of youth-centered community services.  相似文献   
5.
Tc-99m HMPAO was used to evaluate cerebral perfusion in a patient with tuberous sclerosis. The SPECT images demonstrated reduced HMPAO uptake in regions corresponding with MRI-confirmed locations of cortical tubers. These results indicate that the lesions are characterized by vascular perfusion deficits and support the hypothesis that cortical tubers result from developmental abnormalities of the embryonic central nervous system.  相似文献   
6.
Recently introduced prosthetic socket designs for the above-knee amputee (AKA) feature a narrow medial-lateral dimension and emphasize maintenance of the residual limb in full physiologic adduction. Quantitative data on the effect of frontal plane limb position on the isometric hip abductor strength of ten otherwise healthy AKAs were obtained in the standing position. Residual limb isometric and isokinetic abductor strength was also measured and compared with that of the intact limb and with that of ten healthy age-, sex-, and height-matched control subjects using an identical technique. The testing hardware consisted of a modified Cybex II Isokinetic Dynamometer with a custom-made pelvis and trunk stabilizing device. Anthropometric measurements were taken. Results showed an essentially linear increase in residual limb abduction strength with progressive adduction from 30 degrees abduction to 16 degrees adduction. The average increase in abduction torque was .97% (range .29 to 1.5) of the peak neutral position strength per degree of change in femur angle when corrected for the effect of gravity. Similar strength increases with adduction of the femur were found for intact and control limbs. Mean residual limb isometric abduction torque measured 30% less than the intact limb value (p = .0018). The difference between the intact and the control limb mean isometric abduction torques was less than 1%. Isokinetic testing was technically more difficult than isometric testing but revealed similar weakness of the residual limb abductors when compared to the intact and control limbs.  相似文献   
7.
Effects of niacin (nicotinic acid or nicotinamide) supplementation of dairy cow diets on apparent total tract nutrient digestibility, milk yield and milk composition were determined using six mid-lactation Holstein cows in a replicated 3 x 3 Latin square design arranged to test for residual treatment effects. Treatments were control, 12 g/d of nicotinic acid or 12 g/d of nicotinamide. Periods were 14 d long; d 1 to 4 served as an adaptation period before treatment administration commenced (d 5 to 14). Effects of supplemental niacin on plasma nonesterified fatty acid (NEFA) concentrations and plasma glucose concentrations were tested following saline injection on d 10. Blood was then sampled for 5.5 h at 15-min intervals. On d 13, cows were treated similarly except that epinephrine replaced saline. The area below d-10 curves was subtracted from the area below d-13 curves to serve as an indicator of niacin's effect on plasma NEFA and glucose concentration responses to epinephrine injection. Niacin treatments did not change the area differences for plasma glucose compared to the control treatment; however, there was a trend for niacin to reduce the area difference compared to the control treatment for plasma NEFA. Niacin treatments did not alter dry matter intake, nutrient digestibility, milk yield or composition. Niacin supplementation increased the number of entodinia protozoa in rumen fluid.  相似文献   
8.
9.
10.
Psychological and neuropsychological assessments of psychiatric patients are usually designed to contribute to or document psychiatric diagnoses. The present article suggests that reframing the task to focus on cognitive rehabilitation issues can contribute significantly to the treatment of the chronic patient. A test protocol is proposed and exemplary tests suggested.  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