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   12936篇
  免费   1197篇
  国内免费   18篇
耳鼻咽喉   168篇
儿科学   388篇
妇产科学   236篇
基础医学   1820篇
口腔科学   199篇
临床医学   1832篇
内科学   2109篇
皮肤病学   116篇
神经病学   1341篇
特种医学   268篇
外科学   1525篇
综合类   328篇
一般理论   9篇
预防医学   1613篇
眼科学   223篇
药学   948篇
中国医学   17篇
肿瘤学   1011篇
  2021年   174篇
  2020年   137篇
  2019年   177篇
  2018年   222篇
  2017年   176篇
  2016年   169篇
  2015年   193篇
  2014年   259篇
  2013年   460篇
  2012年   614篇
  2011年   669篇
  2010年   379篇
  2009年   312篇
  2008年   554篇
  2007年   682篇
  2006年   627篇
  2005年   630篇
  2004年   573篇
  2003年   548篇
  2002年   553篇
  2001年   292篇
  2000年   328篇
  1999年   258篇
  1998年   152篇
  1997年   128篇
  1996年   112篇
  1995年   113篇
  1994年   111篇
  1992年   247篇
  1991年   254篇
  1990年   259篇
  1989年   247篇
  1988年   245篇
  1987年   230篇
  1986年   214篇
  1985年   179篇
  1984年   173篇
  1983年   138篇
  1982年   134篇
  1981年   134篇
  1980年   123篇
  1979年   143篇
  1978年   126篇
  1977年   111篇
  1976年   120篇
  1975年   118篇
  1974年   149篇
  1973年   130篇
  1972年   102篇
  1971年   101篇
排序方式: 共有10000条查询结果,搜索用时 828 毫秒
51.
52.
The random amplification of polymorphic DNA (RAPD method), was used to derive fragments of DNA of the coccidial parasiteEimeria tenella for use both as genetic markers and as an aid for the discrimination of different wild-type and attenuated populations. Of 41 arbitrarily chosen 9-to 27-mer primers, 24 yielded useful arrays of fragments following low-stringency annealing conditions and the resultant profiles were generally very reproducible. One non-variant fragment of 2 kb hybridised to a single chromosome (number 12) and four variant fragments were identified. These results strongly suggest that the RAPD method may be an extremely useful tool for studies on various aspects of the genetic organisation of coccidial parasites.  相似文献   
53.
54.
One hundred sixty-eight adult siblings and parents from affected and control families were tested for ERP characteristics using two tasks involving an auditory oddball paradigm. Significant within family differences among affected families suggest that risk for developing alcoholism may be seen even in adult subjects who have had experience consuming alcohol. Further, analysis of quantity and recency of drinking in the past seven days were not correlated with either amplitude or latency of P300, suggesting that the within-family differences observed reflect relative risk for developing alcoholism rather than experience with alcohol.  相似文献   
55.
Pulmonary rehabilitation is an effective intervention for patients with chronic obstructive pulmonary disease (COPD). It is usually available only through selected hospitals. A pilot study was undertaken to see if pulmonary rehabilitation performed by the primary health care team in one practice was feasible. Fourteen patients were recruited; 13 completed the programme and one year of follow-up. The programme was well received by patients and staff. There were not enough suitable patients among a practice list of 10,500 to justify the running of this programme for a single practice; one primary care group would suffice  相似文献   
56.
BACKGROUND: A single elevated C-reactive protein (CRP) value predicts mortality in haemodialysis (HD) patients, but the relative importance of repeated vs occasional positive systemic inflammatory response findings is not known. METHODS: To assess the influence on survival of occasional inflammation, CRP, serum albumin (S-Alb) and fibrinogen were analysed bimonthly in 180 HD patients (54% male, 49+/-14 years). Clinically significant inflammation was defined as CRP >5.1 mg/l, based on the receiver operating characteristics curve for CRP as predictor of death. Based on four consecutive measurements of CRP, patients were assigned into three groups: group 1 (n = 74; 41%), no inflammation (CRP < or = 5.1 mg/l in all measurements); group 2 (n = 65; 36%), occasional inflammation (1-3 measurements of CRP > 5.1 mg/l); and group 3 (n = 41; 23%), persistent inflammation (all measurements of CRP >5.1 mg/l). The nutritional status was evaluated by subjective global assessment (SGA) and body mass index (BMI), and the survival (21 months of follow-up) by Kaplan-Meier curve and Cox model. RESULTS: The median and range of CRP values (mg/l) for group 1, 2 and 3 were: 3.2 (3.2-5.1), 3.6 (3.2-54.9) and 13.8 (5.2-82), respectively (P<0.001), whereas the prevalence of malnutrition, assessed by SGA and BMI, did not differ significantly between the groups. The survival rate by Kaplan-Meier analysis was significantly different among the groups (chi2 = 12.34; P = 0.0004). Patients in group 3 showed the highest mortality (34%; P = 0.001), compared with group 1 (8%) and group 2 (14%; P = 0.01), respectively, whereas there was no significant difference in mortality between groups 1 and 2. Age, CRP, S-Alb level and SGA were independent predictors of mortality. CONCLUSION: The patients with a persistent elevation of CRP had a higher mortality rate than the patients with occasional CRP elevation. Thus, persistent, rather than occasional, inflammation is an important predictor of death in HD patients.  相似文献   
57.
58.
59.
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   
60.
The use of biological markers in toxicology   总被引:1,自引:0,他引:1  
  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