全文获取类型
收费全文 | 113061篇 |
免费 | 6307篇 |
国内免费 | 692篇 |
专业分类
耳鼻咽喉 | 1120篇 |
儿科学 | 3611篇 |
妇产科学 | 2696篇 |
基础医学 | 16226篇 |
口腔科学 | 4039篇 |
临床医学 | 10219篇 |
内科学 | 25383篇 |
皮肤病学 | 2811篇 |
神经病学 | 11067篇 |
特种医学 | 2644篇 |
外国民族医学 | 1篇 |
外科学 | 10180篇 |
综合类 | 409篇 |
一般理论 | 50篇 |
预防医学 | 11134篇 |
眼科学 | 1816篇 |
药学 | 7932篇 |
中国医学 | 436篇 |
肿瘤学 | 8286篇 |
出版年
2024年 | 128篇 |
2023年 | 1079篇 |
2022年 | 2327篇 |
2021年 | 3813篇 |
2020年 | 2409篇 |
2019年 | 3221篇 |
2018年 | 3627篇 |
2017年 | 2790篇 |
2016年 | 3229篇 |
2015年 | 3591篇 |
2014年 | 4698篇 |
2013年 | 6111篇 |
2012年 | 9376篇 |
2011年 | 9684篇 |
2010年 | 5298篇 |
2009年 | 4467篇 |
2008年 | 7730篇 |
2007年 | 7730篇 |
2006年 | 7177篇 |
2005年 | 6708篇 |
2004年 | 6040篇 |
2003年 | 5356篇 |
2002年 | 4824篇 |
2001年 | 646篇 |
2000年 | 481篇 |
1999年 | 677篇 |
1998年 | 857篇 |
1997年 | 696篇 |
1996年 | 595篇 |
1995年 | 489篇 |
1994年 | 459篇 |
1993年 | 377篇 |
1992年 | 343篇 |
1991年 | 243篇 |
1990年 | 253篇 |
1989年 | 231篇 |
1988年 | 205篇 |
1987年 | 183篇 |
1986年 | 187篇 |
1985年 | 144篇 |
1984年 | 157篇 |
1983年 | 154篇 |
1982年 | 166篇 |
1981年 | 123篇 |
1980年 | 131篇 |
1979年 | 95篇 |
1978年 | 88篇 |
1977年 | 78篇 |
1976年 | 73篇 |
1974年 | 65篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
We evaluated the effectiveness of statewide bicycle legislation using direct observation of the number of elementary and middle school children riding bicycles with and without helmets to or from school over a 7-year period. The percentage of children wearing helmets increased dramatically over the past 7 years (to a high of 81%) due to the passage of state law that required helmet usage. Rates for elementary school children were consistently higher than rates of middle school children. Numerous children still do not wear helmets, particularly older children. Further interventions are needed to promote helmet wearing. 相似文献
102.
C Caruso G Di Lorenzo M A Modica G Candore M R Portelli G Crescimanno A Ingrassia G B Sangiorgi A Salerno 《Mechanisms of ageing and development》1991,59(1-2):27-35
The evidence from several studies indicates that as individuals age, they may display immune dysfunctions, mostly T cell dysfunctions. Recently, a soluble form of the receptor for interleukin-2 (IL-2) (sIL-2R) has been demonstrated in human sera and in vitro stimulated culture supernatants from human T lymphocytes. In the present paper, we report in vitro sIL-2R production from peripheral blood mononuclear cells in elderly subjects. The results show that no difference exists for unstimulated cultures, whereas after mitogen stimulation the elderly subjects showed the lowest values compared with young ones. These findings suggest that sIL-2R may provide a new tool for the study of T lymphocyte dysfunctions in old age. 相似文献
103.
Elsa J. Brochmann Murray Samuel S. Murray Mario Grisanti Maria Eugenia L. Duarte Marshall R. Urist 《Journal of orthopaedic research》1997,15(4):585-592
The SENCAR (sensitive to carcinogenesis) mouse is a unique tool for investigating the interaction between a specific defect in intracellular signaling, dietary calcium, and metabolic bone disease. The SENCAR mouse was developed by selective breeding for enhanced sensitivity to two-stage carcinogenesis. Its major genetic defect, which renders it exquisitely sensitive to stimulation with diacylglycerol or phorbol esters, is in the regulatory domain of protein kinase C, one of the primary intracellular mediators of hormonal effects. At sexual maturity, SENCAR mice are large and have big bones, but our previous pharmacokinetic studies showed that they accumulate lesscalcium under normal conditions and lose more calcium under adverse conditions than do other, standard strains of mice. To histologically define the effect of low dietary calcium on bone metabolism, we performed histomorphometric analysis of tetracycline-labeled sections of femoral bone from male SENCAR mice maintained on calcium-sufficient and calcium-deficient diets during the critical period from 10 to 14 weeks of age. The bone volume, absolute osteoid volume, and mineral apposition rate were lower at 14 than at 10 weeks of age in SENCAR mice fed 0.02 or 0.6% calcium diets. Calcium deficiency increased the architectural disarray and the probability of observing focal discontinuities in the growth plate. Thus, characteristic features of impaired bone metabolism (low bone volume and apposition rate) develop early in SENCAR mice and are exacerbated by low dietary calcium. Detailed examinations of the histology and biochemistry of SENCAR mouse bone will provide insights into the mechanisms by which specific defects in the signal transduction of protein kinase C contribute to impaired bone metabolism. 相似文献
104.
S Plescia G Daidone D Raffa M L Bajardi A Caruso V Cutuli M Amico-Roxas 《Il Farmaco; edizione pratica》1992,47(4):465-475
A number of new 3-(isoxazol-5-yl)-quinazolin-4(3H)-ones was prepared and tested, together a few analogues previously obtained, for their analgesic, antipyretic and antiinflammatory activities, as well as for their acute toxicity and ulcerogenic effects. In the carrageenan rat foot edema model one of the tested compounds showed activity and LD50 comparable to that of ASA, but the ulceration index approximated zero value. 相似文献
105.
Angela Ohlemacher Rainer Schenk Hans Peter Weitzel Nikolai Tyutyulkov Maria Tasseva Klaus Müllen 《Macromolecular chemistry and physics.》1992,193(1):81-93
The energy gaps of poly(p-arylenevinylene)s with phenylene, naphthylene and anthrylene subunits are determined by extrapolating the UV/VIS spectroscopic data of the oligomers. The band structure of the three polymers was theoretically investigated. The topology-, geometry- and correlation-factors were determined upon which the energy spectra of this class of one-dimensional π-electron systems depend. 相似文献
106.
An unusual case of sundown syndrome is here reported, in which a bilingual patient would involuntarily change languages at sunset. Numerous theories have been advanced in attempting to account for sundowning. Cameron [1] has suggested that nocturnal delirium was based on an inability to maintain a spatial image without the assistance of repeated visualization. Krai [2] and Wolanin and Phillips [3] have argued for a more psychogenic account, by stating that psychosocial stressors may, in concert with impaired cognitive functioning, account for sundowning. The present case concerns a 42-year-old white male who in January 1989 suffered a closed head injury. A thorough personal history as well as a detailed examination of the patient's daily activities allowed us to account for the unusual manner in which the sundowning manifested itself. The uniqueness of this case allows us to underscore both the psychological as well as environmental and neurological factors involved in sundowning. Thus, we have as a consequence been able to synthesize the seemingly disparate accounts of both Cameron and more recent published literature [2, 3]. 相似文献
107.
Driven by research findings regarding the positive relationship between training and enhancement of services, as well as literature on adult learning, the New England Head Start Teaching Center (NEHSTC) was created in 1992 to test the efficacy of participatory, hands-on training. The purpose of this paper is to examine the outcome evaluation results from 4 years of training at the NEHSTC, 1 of 14 federally funded sites, as well as to discuss the implications for delivering this type of participatory training throughout Head Start. Findings suggest that the NEHSTC was successful in implementing high quality, participatory training within the context of an ongoing Head Start program. Head Start staff who participated in the NEHSTC trainings demonstrated gains in knowledge, skills, and expertise compared to similar Head Start employees who did not receive training. Results also reveal a sustained effect of training over time, with NEHSTC participants continuing to demonstrate enhanced knowledge and skills 6 months after training. Similar positive outcomes of training were found for staff with varying levels of experience and holding different Head Start positions. Thus the participatory, hands-on training implemented by the NEHSTC was found to produce positive and lasting outcomes for diverse Head Start staff. An effective and cost efficient model of training Head Start personnel is particularly relevant and timely as Head Start strives to establish universal quality and expansion of services in the 21st Century. The findings are also relevant for improving the quality of all early care and education programs. 相似文献
108.
José Maria Bengoa M.D. 《Nutrition reviews》1997,55(8):309-314
Editors' note: As we approach the end of the 20th century, we will, in Nutrition Reviews, take an occasional look back at developments of the last half-century that have established the underpinnings of public health nutrition as we know it and practice it today. This is also a span of time over which this journal, having begun publication in 1942, has addressed important developments in nutrition and health. Our first retrospective is contributed by Dr. José Maria Bengoa, one of the fathers of international public health nutrition. Dr. Bengoa, whose career has spanned more than 50 years, witnessed the origins of the international nutrition agencies and served in leadership roles at the Pan American Health Organization and the World Health Organization (WHO) from 1955 to 1964, and as director of the WHO Office of Nutrition from 1964 to 1974. 相似文献
109.
Felipe Scalco Manzano DDSc Lucia Mercuri Granero MD Danilo Masiero MD Maria Teresa Botti Rodrigues dos Santos DDSc PhD 《Special care in dentistry》2004,24(4):235-239
This study was designed to verify the safety and efficacy of botulinum toxin type A (BTX-A) used as a neuromuscular block on spastic masticatory musculature of children with cerebral palsy. Six patients who had spastic-tetraplegic cerebral-palsy, aged 5 to 20 years were selected. All patients had spasticity of the jaw muscles, bruxism, lower lip trauma, limited mouth opening, and difficulties in cleaning the oral cavity. The patients were sedated under general anesthesia, while the dentist injected the masseter and temporalis muscles bilaterally with 150 and 75 units of BTX-A each. Clinical examinations were conducted at 7, 14, 30, and 90 days after the initial appointment. We found statistically significant decreases in muscle spasticity and bruxism ( p = 0.002), improved inter-incisal opening ( p = 0.002), improved oral hygiene ( p = 0.031), and less lower lip trauma ( p = 0.060) after the neuromuscular blocking. 相似文献
110.
Neurodevelopmental treatment (NDT) is the most used rehabilitation approach in the treatment of patients with stroke in the Western world today, despite the lack of evidence for its efficacy. The aim of this study was to conduct an intervention check and measure the nurses' competence, in positioning stroke patients according to the NDT approach. The sample consisted of 144 nurses in six neurological wards who were observed while positioning stroke patients according to the NDT approach. The nurses' combined mean competence scores within the wards was 195 (70%) of 280 (100%) possible, and for each ward the mean score varied between 181 (65%) and 206 (74%). This study indicates that nurses working in hospitals where the NDT approach has been implemented have the knowledge and skills to provide NDT nursing. 相似文献