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   9308篇
  免费   768篇
  国内免费   12篇
耳鼻咽喉   125篇
儿科学   276篇
妇产科学   168篇
基础医学   1234篇
口腔科学   161篇
临床医学   1157篇
内科学   1479篇
皮肤病学   95篇
神经病学   871篇
特种医学   202篇
外科学   1187篇
综合类   266篇
一般理论   11篇
预防医学   1196篇
眼科学   172篇
药学   758篇
中国医学   2篇
肿瘤学   728篇
  2022年   73篇
  2021年   119篇
  2020年   93篇
  2019年   139篇
  2018年   136篇
  2017年   129篇
  2016年   116篇
  2015年   133篇
  2014年   169篇
  2013年   282篇
  2012年   410篇
  2011年   436篇
  2010年   248篇
  2009年   216篇
  2008年   354篇
  2007年   420篇
  2006年   390篇
  2005年   385篇
  2004年   363篇
  2003年   325篇
  2002年   330篇
  2001年   257篇
  2000年   288篇
  1999年   216篇
  1998年   102篇
  1997年   70篇
  1996年   83篇
  1995年   73篇
  1992年   224篇
  1991年   227篇
  1990年   228篇
  1989年   220篇
  1988年   225篇
  1987年   208篇
  1986年   187篇
  1985年   144篇
  1984年   135篇
  1983年   110篇
  1982年   84篇
  1981年   90篇
  1980年   77篇
  1979年   119篇
  1978年   100篇
  1977年   87篇
  1976年   84篇
  1975年   88篇
  1974年   123篇
  1973年   106篇
  1972年   84篇
  1971年   78篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
This article addresses cost differences between primary care physicians in private practice and hospital outpatient departments (OPD's). The analysis utilizes ambulatory visit groups (AVG's), the outpatient equivalent of diagnosis-related groups (DRG's), to adjust for case mix. Major findings are that OPD's have higher per visit costs than physicians' private offices; internists are more expensive than general practitioners regardless of site; and ancillary service costs are actually slightly higher in private practice. Any prospective payment system for ambulatory care must consider these costs differences.  相似文献   
992.
A CRAHCA educational program was held recently to determine the changes in the health service environment that are most likely to occur in the near future, and how these changes will affect medical group practice.  相似文献   
993.
994.
995.
The metabolism of [14C]nicotinic acid and [14C]nicotinamide by perfused rat intestine was studied by analyzing the 14C-products formed at various time intervals after these substrates were administered intravascularly or intralumenally. Intermediates in the Preiss-Handler pathway contained isotope when [14C]nicotinic acid was administered by either route. Large amounts of isotope in niacinamide and some in nicotinamide mononucleotide (NMN) were also found indicating substantial NAD-glycohydrolase activity in this intestinal preparation. The products from [14C]nicotinamide also included the metabolites of nicotinic acid, due to deamidation of the substrate in the lumen when the exposure was prolonged. In short term studies the amide was absorbed rapidly by simple diffusion with little hydrolysis to nicotinic acid. The primary labeled form found in the perfusate when [14C]nicotinic acid was administered via the lumen for both recirculating and one pass perfusions was unchanged nicotinic acid. The primary forms found in the perfusate when the amide was given were both the amide and the acid for both one pass and for recirculating experiments. The rapid transport of nicotinamide from the lumen to the perfusate and the lack of 14C-metabolites of nicotinic acid in the intestinal tissue following intralumenal injection of [14C]nicotinamide in the living animal suggest that deamidation in the digestive tract is not a major fate of physiological quantities of niacinamide.  相似文献   
996.
Smallpox and monkeypox in non-human primates   总被引:3,自引:0,他引:3  
In considering global eradication of smallpox the absence of an animal reservoir is important. Present knowledge of experimental infection of non-human primates with variola virus and of a related virus infection in monkeys, termed monkeypox, is examined.  相似文献   
997.
BACKGROUND: It is uncertain whether or not vegetables, fruit, or grains protect against colorectal cancer. OBJECTIVE: In a large prospective study, we investigated the association of vegetable, fruit, and grain intakes with colorectal cancer risk. DESIGN: Between 1993 and 1996, 85 903 men and 105 108 women completed a quantitative food-frequency questionnaire that included approximately 180 foods and beverages in the Multiethnic Cohort Study. A diagnosis of colorectal cancer was made in 1138 men and 972 women after an average follow-up of 7.3 y. Cox proportional hazards models were used to calculate multivariate-adjusted relative risks and 95% CIs for colorectal cancer. RESULTS: In men, multivariate adjustment for energy intake, dietary, and nondietary variables resulted in relative risks in the highest quintile group of 0.74 (95% CI: 0.59, 0.93; P for trend = 0.02) for vegetables and fruit combined, 0.80 (95% CI: 0.64, 0.99; P for trend = 0.09) for fruit alone, and 0.85 (95% CI: 0.69, 1.05; P for trend = 0.05) for vegetables alone. When colon and rectal cases were separated among men, the inverse associations were stronger for colon than for rectal cancer. In women, none of the associations with vegetables, fruit, or vegetables and fruit combined were significant. Grain intake was not associated with colorectal cancer for either men or women. CONCLUSION: The intake of vegetables and fruit was inversely related to colorectal cancer risk among men but not among women. The association appears stronger for colon than for rectal cancer.  相似文献   
998.
Malignant esophago-respiratory fistula is an incurable condition calsing severe distress to those patients suffering from it. Sixty two successive patients with esophago-respiratory fistulae, secondary to squamous cell carcinomas of the esophagus, were intubated for palliation. The first 14 were intubated by a traction technique using the Celestin tube, and the remaining 48 were intubated by the Procter-Livingstone tube inserted by a pulsion method. Celestin intubation had a mortality of 64.3% but 75% of those intubated by the Procter-Livingstone tube were discharged from hospital, swallowing satisfactorily and relieved of their respiratory distress. In our experience the insertion of the Proctor-Livingstone tube by a pulsion technique, can be performed in a few minutes, with little morbidity and allows the patient to be discharged from hospital within 3-4 days of the procedure. It is a successful and acceptable method of treating malignant esophago-respiratory fistulae.  相似文献   
999.
This study compared the bone-mineral density in the proximal part of the femur and the flexion and extension strength of the knee in the fractured and the non-fractured limbs after an uncomplicated fracture of the tibia or femur in children. Thirty-eight children, whose ages ranged from two to fifteen years at the time of the injury, were evaluated at an average of 2.3 years after the injury. The mean difference in bone-mineral density between the fractured and non-fractured limbs was 3.3 per cent (p = 0.004). There was no significant difference between the bone-mineral density of the limbs that had been immobilized for less than four weeks and that of the contralateral, non-fractured limbs. However, the mean difference between the bone-mineral density of the limbs that had been immobilized for more than eight weeks and that of the contralateral limbs was 4.3 per cent (p = 0.006). There was little or no relationship between the time since the injury and the difference in bone-mineral density between the two limbs of the patient at the intervals of follow-up that were studied. No residual weakness in flexion and extension of the knee was detected, and no relationship was established between the limb-to-limb differences in strength and the limb-to-limb differences in bone-mineral density. The residual bone-mineral deficit was found to be minimum after an uncomplicated fracture. This difference, while statistically significant, is unlikely to be clinically important in the long term. However, the fact that there was a deficit raises a potential concern for children who have more severe or repeated injuries.  相似文献   
1000.
Adolescent tibia vara: alternatives for operative treatment.   总被引:4,自引:0,他引:4  
We reviewed the cases of fifteen obese patients (twenty-one extremities) who had had adolescent tibia vara and had been followed for at least two years. Of the nine patients (eleven extremities) who had been initially managed with lateral tibial hemiepiphyseodesis, eight (ten extremities) were skeletally mature at the time of the review (mean duration of follow-up, five years). The mechanical alignment was judged to be excellent in three of these ten extremities, fair in three, and poor in four. Excellent mechanical alignment was defined as a value within the reported normal range of 5 degrees of varus to 2 degrees of valgus. A poor result was defined as alignment that was more than 5 degrees outside the normal range. After secondary operative procedures, three of the extremities for which the result had been poor and one for which it had been fair had excellent alignment. Five of the nine patients had bilateral involvement. Two of them were managed with bilateral tibial hemiepiphyseodesis; two, with contralateral proximal tibial osteotomy; and one had a mild deformity on the contralateral side that was not treated. Six extremities in six patients (two of whom had a contralateral hemiepiphyseodesis) were managed primarily with proximal tibial osteotomy and were evaluated an average of seven years postoperatively. Two additional patients were managed with proximal tibial osteotomy because of residual varus deformity after the hemiepiphyseodesis.(ABSTRACT TRUNCATED AT 250 WORDS)  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