全文获取类型
收费全文 | 2437188篇 |
免费 | 182034篇 |
国内免费 | 3748篇 |
专业分类
耳鼻咽喉 | 33977篇 |
儿科学 | 79394篇 |
妇产科学 | 68485篇 |
基础医学 | 345715篇 |
口腔科学 | 71567篇 |
临床医学 | 216055篇 |
内科学 | 468048篇 |
皮肤病学 | 53252篇 |
神经病学 | 192441篇 |
特种医学 | 97457篇 |
外国民族医学 | 665篇 |
外科学 | 370411篇 |
综合类 | 56655篇 |
现状与发展 | 4篇 |
一般理论 | 772篇 |
预防医学 | 182469篇 |
眼科学 | 56274篇 |
药学 | 188109篇 |
10篇 | |
中国医学 | 5175篇 |
肿瘤学 | 136035篇 |
出版年
2018年 | 23520篇 |
2016年 | 20788篇 |
2015年 | 23706篇 |
2014年 | 32600篇 |
2013年 | 49003篇 |
2012年 | 66515篇 |
2011年 | 70208篇 |
2010年 | 41519篇 |
2009年 | 39390篇 |
2008年 | 66677篇 |
2007年 | 70488篇 |
2006年 | 71823篇 |
2005年 | 69186篇 |
2004年 | 67626篇 |
2003年 | 64764篇 |
2002年 | 63141篇 |
2001年 | 119724篇 |
2000年 | 123516篇 |
1999年 | 104061篇 |
1998年 | 27603篇 |
1997年 | 24703篇 |
1996年 | 24592篇 |
1995年 | 23706篇 |
1994年 | 21993篇 |
1993年 | 20771篇 |
1992年 | 83168篇 |
1991年 | 80495篇 |
1990年 | 79042篇 |
1989年 | 76401篇 |
1988年 | 70395篇 |
1987年 | 69179篇 |
1986年 | 65637篇 |
1985年 | 62937篇 |
1984年 | 46479篇 |
1983年 | 39844篇 |
1982年 | 22868篇 |
1981年 | 20228篇 |
1980年 | 19054篇 |
1979年 | 43558篇 |
1978年 | 29935篇 |
1977年 | 25793篇 |
1976年 | 23630篇 |
1975年 | 25589篇 |
1974年 | 30783篇 |
1973年 | 29673篇 |
1972年 | 27694篇 |
1971年 | 26090篇 |
1970年 | 23936篇 |
1969年 | 22708篇 |
1968年 | 20607篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
991.
To measure intestinal absorption by using a single, random stool sample, polyethylene glycol (PEG), 1 g/d, and a constant diet were given to healthy infants, with a constant PEG-to-macronutrient ratio. After 10 d equilibration, apparent intestinal absorption of macronutrients was estimated from a standard 3-d metabolic balance and compared with that estimated by using the ratio of PEG to macronutrients in a single random sample of feces. Correlation coefficients for this comparison were 0.649, 0.715, and 0.924 for nitrogen, carbohydrate, and fat, respectively. Additionally, apparent intestinal absorptions estimated from two separate consecutive 3-d metabolic-balance studies were compared, showing correlation coefficients of 0.106, 0.653, and 0.463 for nitrogen, carbohydrate, and fat, respectively. The random sample-marker technique appears to be acceptable for measuring apparent absorption of macronutrients and is at least as accurate as a standard 3-d metabolic-balance study. 相似文献
992.
Quantitative studies of morbidity, food intake, and somatic growth were done prospectively during 14 mo for 70 children aged 5-18 mo in two Bangladeshi villages. When random-effect regression models were used, monthly changes in weight were inversely related to proportions of days in the month with fever and diarrhea and positively related to energy intake per kilogram body weight. Interestingly, weight changes did not vary with age in this interval. Estimates indicate that increasing energy intakes to the recommended World Health Organization level would have a significantly greater effect on weight gain than would the elimination of diarrhea and fever. With energy at recommended intake and diarrhea and fever prevalence as found in US children, weight gain is predicted to be near that of the international reference population. Therefore, interventions aimed at improving dietary intake may be as important as infection-control programs for improving growth of children in poor developing nations. 相似文献
993.
Health care use among young children in day care. Results in a randomized trial of early intervention 总被引:2,自引:0,他引:2
Exposure of young children to group day-care settings increases the risk of illness and may result in higher use of medical care. These observations raise concerns that the use of such settings for early intervention programs for low-birth-weight infants may increase the already high burden of medical care costs incurred by these children and their families. To address the question of medical care use associated with center-based care, we examined the hospital-based and ambulatory care reported for participants of the Infant Health and Development Program. This project is a multisite randomized trial of an early intervention program for preterm low-birth-weight infants with an intervention including 2 years of center-based care. The Intervention group did not differ in hospital-based care and averaged only two more physicians' visits over the 3-year observation period than the comparison group. We conclude that early intervention programs involving high-quality group care are not accompanied by substantial increases in health care use. 相似文献
994.
995.
996.
997.
Complications associated with central venous catheters inserted in critically ill neonates 总被引:2,自引:0,他引:2
V Hruszkewycz P C Holtrop D G Batton R S Morden P Gibson J D Band 《Infection control and hospital epidemiology》1991,12(9):544-548
OBJECTIVE: To assess the incidence and spectrum of complications associated with central venous catheter (CVC) placement in the critically ill infant. DESIGN: A prospective study of all babies hospitalized in a neonatal intensive care unit (NICU) from January 1989 to December 1989. Potential risk factors associated with infection were evaluated by a case-control comparison. SETTING: Conducted at a university-affiliated, tertiary care community hospital. PATIENTS: Neonates requiring intensive care and a central venous catheter. Controls consisted of noninfected babies. RESULTS: Of 263 critically ill neonates, only 13 (4.9%) required a CVC insertion. Seventeen CVCs were placed in these 13 neonates for a total duration of 600 days (median, 32 days/cannula). Fifteen (88%) of these cannulas had one or more complications during its catheter life including dislodgement or leakage (53%), occlusion or thrombosis (47%), infections (29%), or minor bleeding (12%). Five babies (29%) developed 6 episodes of bloodstream infection including 3 sporadic cases due to Staphylococcus epidermidis and a cluster of fungemia due to Malassezia furfur associated with lipid emulsion therapy. Infants with a CVC-associated infection were a younger gestational age (24 weeks versus 32 weeks, p = .04) and weighed less at birth (580 g versus 1285 g, p = .02). The overall rate of bloodstream infection was one episode per 100 days of catheter use. CONCLUSIONS: CVCs may be lifesaving to a critically ill neonate, but complications occur frequently. Use must be restricted to infants in whom alternate delivery routes of intravenous therapy or support are otherwise unavailable. 相似文献
998.
999.
D P Taggart D C McMillan T Preston R Richardson A Shenkin H J Burns D J Wheatley 《Nutrition (Burbank, Los Angeles County, Calif.)》1991,7(4):271-274
Total energy expenditure (TEE) was measured by doubly labeled water in 13 preoperative patients undergoing elective coronary artery surgery and compared to resting energy expenditure (REE) measured by indirect calorimetry (IC) calculated from the Harris-Benedict (HB) formula or from formulas based on midarm circumference and arm muscle circumference. Mean REE measured by IC and calculated from the HB, midarm circumference, arm muscle circumference formulas were 62, 75, 62, and 69%, respectively, of TEE measured by doubly labeled water. REE measured by IC correlated significantly with that predicted by the HB (p = 0.006) but not the anthropometric formulas. The relationship between REE derived from anthropometric predictive formulas and REE measured by IC is altered in ischemic heart disease. 相似文献
1000.