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   62807篇
  免费   3390篇
  国内免费   141篇
耳鼻咽喉   623篇
儿科学   1718篇
妇产科学   1590篇
基础医学   9945篇
口腔科学   672篇
临床医学   5414篇
内科学   14083篇
皮肤病学   1233篇
神经病学   5615篇
特种医学   2067篇
外国民族医学   32篇
外科学   9052篇
综合类   327篇
一般理论   23篇
预防医学   4295篇
眼科学   992篇
药学   4071篇
中国医学   114篇
肿瘤学   4472篇
  2023年   253篇
  2022年   214篇
  2021年   796篇
  2020年   487篇
  2019年   886篇
  2018年   1462篇
  2017年   1010篇
  2016年   1064篇
  2015年   1327篇
  2014年   1447篇
  2013年   2339篇
  2012年   3732篇
  2011年   3793篇
  2010年   2082篇
  2009年   1780篇
  2008年   3618篇
  2007年   3716篇
  2006年   3635篇
  2005年   3811篇
  2004年   3658篇
  2003年   3474篇
  2002年   3487篇
  2001年   1503篇
  2000年   1540篇
  1999年   1284篇
  1998年   552篇
  1997年   491篇
  1996年   436篇
  1995年   444篇
  1994年   381篇
  1993年   377篇
  1992年   831篇
  1991年   693篇
  1990年   701篇
  1989年   711篇
  1988年   624篇
  1987年   609篇
  1986年   538篇
  1985年   535篇
  1984年   422篇
  1983年   371篇
  1982年   267篇
  1981年   283篇
  1980年   242篇
  1979年   319篇
  1978年   236篇
  1977年   228篇
  1976年   200篇
  1975年   196篇
  1974年   194篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
21.
22.
23.
PURPOSE: The advantages of a focometer (FOCOMETER) over other methods of refraction for use in developing countries are that it is lightweight, compact, relatively inexpensive, fairly quick, and easy to use with minimal training. This clinical trial compared the repeatability, validity, and ease of use of the focometer with an autorefractor. METHODS: The refractive status of the right eye of 80 participants was determined with an autorefractor (Canon RK3). Three measurements were also taken with the focometer. RESULTS: The spherical equivalent (M) of the focometer was 0.25 D more positive than the autorefractor (p < 0.001) and 84% of measurements were within 0.75 D of the autorefractor. The autorefractor detected astigmatism in 91% (73) of the eyes, whereas the focometer identified only 32% (26). The design of the clock target restricts cylinder axis accuracy to the nearest 15 degrees . There was evidence of a learning effect for the focometer: the second and third measurements were more repeatable in the untrained group. There were no differences between the mean (1.03 +/- 2.28) and third focometer (-1.05 +/- 2.32) measurements (p = 0.34). However, using the third focometer measurement, 94% of participants had visual acuities of at least 6/12(-2). CONCLUSIONS: This study highlighted the focometer's restricted power range, inaccuracy of astigmatism and axis determination, and dependence on subject understanding and compliance. Therefore, in most clinical settings, the focometer would not be adequate for quantifying refractive error, but the focometer spherical equivalent was within acceptable limits of the autorefractor, and the visual acuity with lenses determined by the focometer indicates its potential usefulness in public health settings, especially where only spherical ready-made spectacles are dispensed. There may be more cost-effective ways to determine refractive error in these circumstances. A potentially important enhancement in focometer methodology that improves its ease of use was identified: use only the third measurement for each eye.  相似文献   
24.
25.
Pheochromocytoma may lead to important emergency situations, ranging from cardiovascular emergencies to acute abdomen and multiorgan failure. It is vital to think about this disease in any emergency situation when conventional therapy fails to achieve control or symptoms occur that do not fit the initial diagnosis. The importance of keeping this diagnosis in minds is underscored by the fact that, in 50% of pheochromocytoma patients, the diagnosis is initially overlooked. Two other tumors of the sympathetic nervous system, neuroblastoma and ganglioneuroma, are less commonly associated with emergency conditions. If they occur, they are often linked to catecholamine excess, paraneoplastic phenomena, or local tumor mass effect.  相似文献   
26.
27.
Postpartum fatigue is a normal condition that most women experience. Breastfeeding is often associated in women's minds as contributing to the feeling of overall perceived fatigue, and many women indicate that they have ceased breastfeeding because of fatigue. However, the relationship between feeding choice and perceived fatigue has never been established. Two hundred and fifty-three women participated in a study examining whether perceived fatigue differed for bottle-feeding and breastfeeding women at 3 different times during the postpartum period (2-4 days, 6 weeks, and 12 weeks postpartum). Results showed no significant differences for these 2 groups, suggesting that perceived fatigue during the postpartum period is not dependent on feeding choice. Additional analyses examining other variables with a potential effect were nonsignificant. Because perceived physical fatigue does not appear to be dependent on feeding choice, women should be prepared for the feeling of perceived fatigue during the postpartum period while at the same time be reassured that feeding choice is not correlated.  相似文献   
28.
Radiological lymphography presents drawbacks among which the risk of aggravation of the edema is most prominent. The authors report their experience with isotopic lymphography which best reproduces the physiological conditions of lymphatic drainage; it provides informations on the dermal or canalicular drainage route, the possible peripheral stasis or lymph leakage.  相似文献   
29.
30.
Patients with neuromuscular diseases have protein malnutrition related to the muscle mass decrease. When associated with a decrease in food intake below requirements, patients become cachectic. Respiratory complications are then frequent and severe. In case of respiratory distress, the acute stress might aggravate the protein loss which will be particularly difficult to restore if the muscular activity is reduced. Although there are no curative therapies for neuromuscular diseases but all symptomatic treatments are useful in maintaining function and quality of life; therefore the prevention of malnutrition is essential. Nutritional care is difficult because of the lack of norms for body composition and protein and energy requirements. The nutritional support must take into account the swallowing difficulties, the digestive and polyvisceral involvement and the natural history of the disease. The nutritional support is usually enteral. Feeding through a gastrostomy tube, feasable at home, has improved the quality of life of the patient. Parenteral nutrition is prescribed for limited periods for surgery or acute respiratory failure.  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