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   14549篇
  免费   1129篇
  国内免费   259篇
耳鼻咽喉   92篇
儿科学   300篇
妇产科学   165篇
基础医学   1680篇
口腔科学   459篇
临床医学   1546篇
内科学   2579篇
皮肤病学   121篇
神经病学   1031篇
特种医学   456篇
外国民族医学   2篇
外科学   1238篇
综合类   1059篇
一般理论   10篇
预防医学   2309篇
眼科学   260篇
药学   1562篇
  4篇
中国医学   469篇
肿瘤学   595篇
  2024年   23篇
  2023年   296篇
  2022年   445篇
  2021年   789篇
  2020年   506篇
  2019年   627篇
  2018年   543篇
  2017年   516篇
  2016年   506篇
  2015年   516篇
  2014年   841篇
  2013年   1334篇
  2012年   678篇
  2011年   797篇
  2010年   657篇
  2009年   617篇
  2008年   697篇
  2007年   620篇
  2006年   502篇
  2005年   447篇
  2004年   451篇
  2003年   375篇
  2002年   301篇
  2001年   260篇
  2000年   221篇
  1999年   200篇
  1998年   187篇
  1997年   189篇
  1996年   176篇
  1995年   159篇
  1994年   125篇
  1993年   120篇
  1992年   112篇
  1991年   89篇
  1990年   95篇
  1989年   89篇
  1988年   108篇
  1987年   83篇
  1986年   69篇
  1985年   88篇
  1984年   78篇
  1983年   62篇
  1982年   61篇
  1981年   58篇
  1980年   43篇
  1979年   45篇
  1978年   32篇
  1977年   20篇
  1976年   23篇
  1975年   17篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
11.
《Vaccine》2021,39(34):4759-4765
Dengue vaccination would enhance the control of dengue, one of the most frequent vector-borne viral diseases globally. CYD-TDV is the first dengue vaccine to be licensed, but global uptake has been hampered due to its use being limited to seropositive persons aged 9 years and above, and the need for a 3-dose schedule. The Partnership for Dengue Control (PDC) organized a meeting with key opinion leaders and stakeholders to deliberate on implementation strategies for the use of CYD-TDV. New data have emerged that support the shortening of the primary schedule from a 3 to 2 dose schedule, extending the age range below 9 to 6 years of age, and expanding the indication from endemic populations to also include travelers to endemic areas. Cost-effectiveness may improve with the modified 2-dose regimen and with multiple testing. Strategies to implement a dengue vaccination program have been developed, in particular school-based strategies. A range of delivery scenarios can then be considered, using various settings for each step of the intervention. However, several challenges remain, including communication about limiting the use of this vaccine to seropositive individuals only. Affordability will vary from country to country, as will government commitment and community acceptance. Well-tailored communication strategies that target key stakeholders are expected to make up a significant part of any future dengue vaccination program.  相似文献   
12.
13.
目的:探讨缺血再灌注脑组织病理形态及丙二醛含量变化的关系.方法:阻断双侧颈总动脉和椎动脉结合低血压法复制兔脑完全性缺血再灌注模型,观察心脉龙对脑组织病理形态变化及脂质过氧化的影响.结果:心脉龙能抑制膜脂质过氧化作用,且缺血再灌注脑组织丙二醛含量变化与其病理形态改变具有一致性.结论:动态观察血液丙二醛,可作为评价脑缺血性疾病治疗和预后的检测指标.  相似文献   
14.
Detection of non-palpable early splenic enlargement may aid diagnosis of primary polycythaemia (PP) and primary thrombocythaemia (PT). In this study linear spleen sizing by ultrasound has been compared with spleen volume estimation by single photon emission computerized tomography (SPECT) in 26 patients. Spleen length by ultrasound correlated well with SPECT volume estimation.
Ultrasound spleen length was also measured in 60 normal control subjects where the upper limit of the 95% reference range was 11.6 cm. Changes in spleen length with both age and body weight were substantial and overshadowed the imperfect reproducibility of this method. Therefore, interpretation of an individual's measured spleen length should be in relation to that predicted for adults of the same age and weight, particularly at the extremes of the younger, heavier patients and also the older, lighter patients.
Ultrasound spleen lengths of different patient groups (21 PP, 26 PT, 17 idiopathic erythrocytosis, 12 secondary polycythaemia, nine apparent polycythaemia) were compared both using the measured overall reference range and the differences from the values predicted for their age and weight. The comparison showed that almost all patients with PP whose spleens were not palpable had spleen lengths greater than the upper limit for the normal control group, but separation from the other patient groups was incomplete.
Detection of non-palpable splenomegaly by ultrasound length should remain a 'minor' criterion amongst the 'proposed modified diagnostic criteria' of PP.  相似文献   
15.
Twenty-eight members of the general public, with little nutritional knowledge and no previous commitment to dietary change, completed 7-day-weighed dietary diaries. They then attempted to change their diets, where appropriate, in line with current nutritional guidelines.
The panel achieved changes in diet that were consistent with the recent recommendations but several problems arose. In particular, although fat levels were reduced, energy levels fell and fibre goals were not reached; in addition, certain of the initial vitamin and mineral intakes gave cause for concern. These results emphasize the importance of giving advice not only about foods that might be reduced in the diet, but also about food that might be used as alternatives. They also illustrate the difficulty of persuading people to make radical changes to their eating habits even when given personal advice from a nutritionist.
The panel was small and not necessarily representative, but the results illustrate the need for more dietary analysis studies. It is not enough simply to formulate appropriate guidelines from a nutritional point of view; it is also important to ensure that the public understands them and that people make sensible decisions about their diet.  相似文献   
16.
In normal adult cats we measured the density of staining for the activity of succinate dehydrogenase (SDH staining) in ventral horn cells of different sizes. The measurements were restricted to that part of the lumbar ventral horn (L6-L7) which is known to contain motoneurones of the peroneal nerve. A statistically significant tendency was found for the SDH staining to be denser in smaller than in larger neurones within the size range of a motoneurones (soma diameter greater than 40 microns). These results are consistent with recently published evidence for ventral horn cells of rats and qualitatively similar relationships between size and SDH staining have also been observed among skeletal muscle fibres (confirmed for mixed muscle of cat in present study). In hindlimb muscles, size as well as SDH staining are known to be markedly activity-dependent. We tested whether this is the case for peroneal motoneurones as well by analyzing the effects of chronic nerve stimulation on the properties of neurones within the appropriate region of the ventral horn. Prior to the final acute experiment, these cats had been subjected to a left-side dorsal rhizotomy and hemispinalization. By aid of a portable mini-stimulator, the left-side common peroneal nerve was activated by repetitive pulses during 50% of total time per day (intra-activity rate: 10, 20 or 40 Hz). After 8 weeks of such treatment, cell sizes as well as the densities of SDH staining showed hardly any differences between peroneal ventral horn cells of the experimental and control sides of the spinal cord.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
17.
Recent New Labour policy for the ‘modernisation’ of Government places a good deal of emphasis on decentralisation. This emphasis is particularly marked in relation to the organisation of primary care. However, like hospitals and other National Health Service institutions, primary care trusts (PCTs) are subject to a substantial raft of centrally established performance targets and indicators, including those which contribute to the public award of between zero and three performance ‘stars’. This raises questions about the extent to which employees can exercise autonomy in the context of rigid top‐down directives. This paper presents findings from a study using participant observation and interviews to examine the impact of a training course aimed ostensibly at increasing employee autonomy in an English PCT. The suggestion is that attempts to make employees more autonomous can be seen as a strategy for increasing central control based upon the internalisation by the employees of centrally promulgated values. The attraction of such strategies is that they may be potentially more effective and less costly than alternative strategies of direct control. However, the study suggests that the outcome of attempts by such methods as programmes to increase employee autonomy may be very different from those intended.  相似文献   
18.
This paper outlines the programming model employed by the Soul City Institute for Health and Development Communication, a South African NGO, in using ‘edutainment’ to facilitate social change. The paper refers to the intersection of this model and current thought on health promotion and various social change theories. It also discusses key challenges and factors contributing to sustainability over 12 years.  相似文献   
19.
The calculation of the extent of the ring scotoma around positive lenses, as conventionally taught to students of clinical optics, indicates that the scotoma is of a significant size. Using knife-edge lenses this study shows that the calculations are invalid due to the finite size of the eye's entrance pupil and in many instances the scotoma is shown not to exist. The effect noticed in clinical practice is probably largely due to the frame and the edging techniques used which add to the refractive scotoma which is present with high powered lenses, large apertures and/or small pupil sizes.  相似文献   
20.
Chronological changes in the complement system in sepsis   总被引:6,自引:0,他引:6  
The time courses of serum complement levels and the severity of sepsis were compared in two groups of septic patients, one in which the patients survived (surviving group) and one in which they did not (nonsurviving group). The components of the complement system, namely, C3a, C4a, C5a, CH50, C3, C4, and C5, were measured at several points in time after the diagnosis of sepsis had been established. A 2-antibody radioimmunoassay was used to measure C3a, C4a, and C5a; the latex agglutination test was used to measure C3 and C4; nephelometry was used to measure C5; and Meyer's 50% hemolysis method was used to measure CH50. Following the diagnosis of sepsis, the levels of CH50, C3, and C4 were significantly lower in the nonsurviving than the surviving group, while the levels of C3a and C4a were significantly higher in the nonsurviving than the surviving group. The C5a levels were significantly higher in the nonsurviving than the surviving group, although no significant intergroup differences were subsequently noted. These results suggest that the serum levels of C3a, C4a, C5a, CH50, C3, and C4 could serve as indices of the severity of sepsis. Thus, monitoring the complement system may be useful for predicting the outcome of patients with sepsis.  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