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   2231867篇
  免费   156131篇
  国内免费   5498篇
耳鼻咽喉   30530篇
儿科学   68183篇
妇产科学   58978篇
基础医学   322987篇
口腔科学   64241篇
临床医学   205230篇
内科学   428968篇
皮肤病学   45982篇
神经病学   182167篇
特种医学   85580篇
外国民族医学   453篇
外科学   333622篇
综合类   44449篇
现状与发展   2篇
一般理论   703篇
预防医学   170338篇
眼科学   50390篇
药学   167956篇
  9篇
中国医学   5199篇
肿瘤学   127529篇
  2019年   17078篇
  2018年   25258篇
  2017年   19370篇
  2016年   21776篇
  2015年   24803篇
  2014年   33019篇
  2013年   50079篇
  2012年   69376篇
  2011年   72473篇
  2010年   42478篇
  2009年   39129篇
  2008年   68341篇
  2007年   72305篇
  2006年   73098篇
  2005年   70979篇
  2004年   68077篇
  2003年   65249篇
  2002年   63604篇
  2001年   108345篇
  2000年   111903篇
  1999年   93836篇
  1998年   24593篇
  1997年   21998篇
  1996年   21601篇
  1995年   20273篇
  1994年   18880篇
  1993年   17598篇
  1992年   72150篇
  1991年   70051篇
  1990年   67883篇
  1989年   65289篇
  1988年   60042篇
  1987年   58514篇
  1986年   55282篇
  1985年   52918篇
  1984年   38990篇
  1983年   33058篇
  1982年   18757篇
  1979年   35369篇
  1978年   24512篇
  1977年   20479篇
  1976年   19098篇
  1975年   20403篇
  1974年   24745篇
  1973年   23761篇
  1972年   22293篇
  1971年   21015篇
  1970年   19644篇
  1969年   18191篇
  1968年   17024篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
In the processing of the waste products of phosphorus containing fertilizer production, several major health-related factors were identified depending on the industrial site's peculiarities: unfavourable microclimate conditions (both cold and heat), relative temperature differences, noise and vibration caused by the equipment, semi-product's, additives' and finished product's dusts, fluorine- and phosphorus-containing substances' affects and poor illumination. The proposed data were used for health-related improvements in the occupational conditions.  相似文献   
993.
994.
995.
The contributors propose a selective photometric technique for detection of sodium and potassium cyanides in different washings, sewage, overalls extraction. The technique was based on the formation of a polymetyne dye, and barbituric acid and pyridine reactions. It proved efficient in detecting the cyanides within 0.01-0.054 mg/dm3, 1-100 mg/l, 0.08-1.24 mg/dm3 with deviations not exceeding 23%. Duration of the test was limited to 25-30 min.  相似文献   
996.
Results are presented from approximately 9000 Rn measurements made in New York state, North Carolina, and South Carolina. The estimated statewide geometric mean concentrations were 28.1 Bq m-3 and 55.8 Bq m-3 for basements in New York state, 27.5 Bq m-3 for living rooms and 108.9 Bq m-3 for basements in North Carolina, and 25.0 Bq m-3 for living rooms in South Carolina.  相似文献   
997.
In tube-fed patients, dietary fiber is often used to manage constipation/diarrhea. Dietary fiber consists of water-soluble and insoluble plant compounds that are resistant to digestion by small-bowel enzymes but are fermented to varying degrees by colonic bacteria. Many physiologic effects of fiber may be related to the degree of fermentation. Few controlled studies of fiber-containing tube feedings have been performed. These studies have limitations and are nondefinitive as to whether fiber prevents or controls constipation/diarrhea. Constipation in tube-fed patients has not been shown to respond to mixed soluble/insoluble fiber in the few studies performed to date. Likewise, fiber may be of only limited benefit in controlling diarrhea in acute illness because of such factors as stress or medication. Fiber does play a role in maintaining gut integrity in all patients, whether they have diarrhea or not. Fiber may be recommended as part of a standard tube-feeding regimen to help assure gut mucosal integrity but not specifically to treat constipation/diarrhea. Further studies are necessary before the role of fiber in the management of constipation/diarrhea in tube-fed patients is determined.  相似文献   
998.
Weight loss in women participating in a randomized trial of low-fat diets   总被引:2,自引:0,他引:2  
We examined weight changes over 1 and 2 y in 303 women enrolled in a low-fat dietary-intervention trial. Participants were randomly assigned to an intervention group that received intensive instruction in maintaining a low-fat diet or to a control group. After 1 y intervention-group women had decreased fat intake by 45.3 g (from 39.2% to 21.6% energy from fat) and weight by 3.1 kg (all P less than 0.0001); control-group women decreased fat intake by 8.8 g (from 38.9% to 37.3% energy from fat) and weight by 0.4 kg. In both univariate analyses and multivariate models, weight loss was more strongly associated with change in percent energy from fat than with change in total energy intake. These data, which are consistent with both epidemiologic and clinical studies, suggest that body adiposity is a function both of energy balance and the proportion of energy derived from fat.  相似文献   
999.
We have developed a unique, family-oriented approach to lowering plasma cholesterol concentrations in persons with familial hyperlipidemias. The approach includes individual clinic visits and group nutrition classes and uses dietary goals outlined in The New American Diet. A series of 13 nutrition classes is presented to small groups, usually composed of relatives from pedigrees with familial hypercholesterolemia or other familial hyperlipidemias. Dietary action goals, cooking demonstrations, food tasting, and finger-stick plasma cholesterol determinations are important components of the classes. Problem-solving discussion is encouraged in the group. Over the past 4 years, 143 hyperlipidemic individuals, along with at least 94 unaffected family members, have participated in 31 groups, which have met for at least six classes. Many clinic participants lower plasma cholesterol by 20% or more. Keys to the success of this program include emphasizing dietary therapy, using the family setting for nutrition intervention, providing hands-on experience with food and recipes, promoting problem solving for dietary action goals, measuring blood cholesterol during classes, and encouraging long-term follow-up for participants with physicians and dietitians.  相似文献   
1000.
Adipose tissue fatty acid composition, serum lipid profile, and dietary intake of 37 patients on maintenance hemodialysis were studied. In August 1982, 1984, and 1986, analyses were carried out in 15 normotriglyceridemic (NTG) and 22 hypertriglyceridemic (HTG; type IV hyperlipidemia) patients. No correlations were found between dietary intake of polyunsaturated fatty acids (PUFAs), ratio of polyunsaturated to saturated fatty acids (P-S ratio), and carbohydrate content on the one hand and serum lipid concentrations on the other in the two groups. Adipose tissue linolenic acid correlated negatively with serum cholesterol in both groups. Strong correlations were found between dietary intake of PUFAs and adipose tissue linoleic acid content, between PUFAs and the double-bond index, between P-S ratio and adipose tissue linoleic acid content, and between P-S ratio and the double-bond index. No significant differences in dietary intake or adipose tissue fatty acid composition were observed between NTG and HTG patients. Thus, no evidence was found for exogenous dietary influences on serum lipid concentrations. The adipose tissue linoleic acid content did reflect the dietary intake of PUFAs.  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