全文获取类型
收费全文 | 7946篇 |
免费 | 590篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 63篇 |
儿科学 | 309篇 |
妇产科学 | 215篇 |
基础医学 | 1302篇 |
口腔科学 | 117篇 |
临床医学 | 938篇 |
内科学 | 1582篇 |
皮肤病学 | 141篇 |
神经病学 | 1075篇 |
特种医学 | 91篇 |
外科学 | 616篇 |
综合类 | 62篇 |
一般理论 | 14篇 |
预防医学 | 1021篇 |
眼科学 | 56篇 |
药学 | 432篇 |
中国医学 | 15篇 |
肿瘤学 | 507篇 |
出版年
2023年 | 44篇 |
2022年 | 74篇 |
2021年 | 225篇 |
2020年 | 129篇 |
2019年 | 228篇 |
2018年 | 221篇 |
2017年 | 158篇 |
2016年 | 190篇 |
2015年 | 204篇 |
2014年 | 276篇 |
2013年 | 427篇 |
2012年 | 624篇 |
2011年 | 608篇 |
2010年 | 325篇 |
2009年 | 270篇 |
2008年 | 465篇 |
2007年 | 557篇 |
2006年 | 507篇 |
2005年 | 494篇 |
2004年 | 459篇 |
2003年 | 442篇 |
2002年 | 390篇 |
2001年 | 77篇 |
2000年 | 36篇 |
1999年 | 50篇 |
1998年 | 101篇 |
1997年 | 81篇 |
1996年 | 89篇 |
1995年 | 58篇 |
1994年 | 54篇 |
1993年 | 67篇 |
1992年 | 40篇 |
1991年 | 30篇 |
1990年 | 36篇 |
1989年 | 32篇 |
1988年 | 31篇 |
1987年 | 27篇 |
1986年 | 22篇 |
1985年 | 23篇 |
1984年 | 36篇 |
1983年 | 19篇 |
1982年 | 43篇 |
1981年 | 47篇 |
1980年 | 24篇 |
1979年 | 16篇 |
1978年 | 23篇 |
1977年 | 18篇 |
1976年 | 16篇 |
1971年 | 12篇 |
1970年 | 11篇 |
排序方式: 共有8556条查询结果,搜索用时 141 毫秒
11.
Gale Haradon Barbara Bascom Cristiana Dragomir Virginia Scripcaru 《Occupational therapy international》1994,1(4):250-260
Infants living in an orphanage (n = 22) in Romania were assessed on the Test of Sensory Functions in Infants (TSFI). Testing of the institutionalized infants was done before and 6 months after an enriched caregiver intervention program. Results showed significant changes in areas of reactivity to tactile deep pressure, visual-tactile integration, oculomotor control, reactivity to vestibular stimulation and total test responses. No significant changes occurred in the area of adaptive motor functions. Effects of sensory deprivation resulting from institutional settings and changes that can occur from enriched caregiver environments are discussed. 相似文献
12.
13.
14.
Virginia Berridge 《Medical history》1997,41(3):390-391
15.
Abdulmassih S. Iskandrian Jeffrey Johnson Tung T. Le Valerie Wasserleben Virginia Cave Jaekyeong Heo 《Journal of nuclear cardiology》1994,1(2):144-149
Background
This study compared the prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging with that of treadmill exercise score in medically treated patients with coronary artery disease (CAD) 相似文献16.
β-Adrenergic receptors (βAR) in the medial nuclei of tractus solitarii (m-NTS) and area postrema (AP) may bind to catecholamines released from neurons, whereas only the AP has fenestrated capillaries allowing access to circulating catecholamines. Since varied autonomic responses are seen following βAR activation of the dorsal vagal complex, including the m-NTS and AP, we hypothesized that there might be a cellular basis for varied responses to βAR stimulation that depends pn the differential access to circulating catecholamines. Therefore, we comparatively examined the ultrastructural localization of the βAR in relation to catecholaminergic neurons in these regions. An antibody directed against the C-terminal tail (amino acids 404–418) of hamster β-adrenergic receptor (βAR404) was used in this study. The localization of βAR404 was achieved by the avidin-biotin peroxidase complex (ABC) technique in combination with a pre-embed immunogold labeling method to localize tyrosine hydroxylase (TH), the catecholamine-synthesizing enzyme. Within m-NTS and at subpostremal border, labeling for βAR404 was evident along the intracellular surface of plasma membranes of small, apparently distal, astrocytic processes. Astrocytic processes with βAR404-immunoreactivity formed multiple, thin lamellae around TH-labeled and non-TH neuronal cell bodies and dendrites. βAR404-immunoreactive astrocytes also extended end-feet around blood vessels and surrounded groups of axon terminals that were directly juxtaposed to each other. Some, but not all, of these axons demonstrated TH-immunoreactivity. Fewer βAR404-immunoreactive astrocytes were detected in AP, regardless of their proximity to catecholaminergic processes or blood vessels. The present astrocytic localization of βAR404, together with the earlier, neuronal localization of βAR's third intracellular loop, suggest that the βAR may be substantially different between neurons and astrocytes. The regional difference in the prevalence of βAR404-immunoreactive astrocytes suggests that these receptive sites may either: (i) be preferentially activated by catecholamines released from terminals rather than circulating catecholamines; or (ii) be down-regulated in AP due to blood-born substances, such as catecholamines. The extensive localization of βAR in the border between m-NTS and AP also suggests that catecholaminergic activation of these astrocytes may dictate the degree of diffusion of catecholamines which are of neuronal or vascular origin. The specific localization of βAR404-immunoreactivity to the more distal portions of astrocytes suggests the possibility that astrocytes have restrictive distributions of βAR and that the β-adrenergic activation lead to morphological or chemical changes that are also localized to the distal portions of astrocytes. Additionally, the detection of βAR404 in astrocytes contacting non-TH-immunoreactive neurons suggests the possibility for catecholaminergic modulation of non-catecholaminergic neurons via the activation of astrocytes. 相似文献
17.
18.
David H. Howard Laura A. Siminoff Virginia McBride Monica Lin 《Health services research》2007,42(6P1):2160-2173
Objective. The Organ Donation Breakthrough Collaborative is a quality improvement initiative to encourage adoption of "best practices" for identifying potential donors and obtaining consent for deceased organ donation. We evaluate the impact of the first phase on organ donation rates.
Setting. We study donation rates in the 95 hospitals that participated in the first phase and a control group of 125 hospitals.
Design. We use a controlled pre/post design. The preperiod is the year before the start of the Collaborative (September 2002 to August 2003), the postperiod is the final 6 months of the first phase (March 2004 to August 2004).
Data. We use administrative data from the Organ Procurement and Transplantation Network to compute the conversion rate in each hospital group and time period. The conversion rate is the proportion of eligible donors who became actual donors.
Principal Findings. Preperiod conversion rates in Collaborative and control hospitals were similar: 52 and 51 percent, respectively. In the postperiod, the conversion rate increased to 60 percent among Collaborative hospitals and remained at 51 percent among control hospitals. The relative change was 8 percentage points (95 percent confidence interval: 2–13: p <.001).
Conclusions. Our findings suggest that the Breakthrough Collaborative led to an increase in donation rates at participating hospitals. 相似文献
Setting. We study donation rates in the 95 hospitals that participated in the first phase and a control group of 125 hospitals.
Design. We use a controlled pre/post design. The preperiod is the year before the start of the Collaborative (September 2002 to August 2003), the postperiod is the final 6 months of the first phase (March 2004 to August 2004).
Data. We use administrative data from the Organ Procurement and Transplantation Network to compute the conversion rate in each hospital group and time period. The conversion rate is the proportion of eligible donors who became actual donors.
Principal Findings. Preperiod conversion rates in Collaborative and control hospitals were similar: 52 and 51 percent, respectively. In the postperiod, the conversion rate increased to 60 percent among Collaborative hospitals and remained at 51 percent among control hospitals. The relative change was 8 percentage points (95 percent confidence interval: 2–13: p <.001).
Conclusions. Our findings suggest that the Breakthrough Collaborative led to an increase in donation rates at participating hospitals. 相似文献
19.
20.
This study is part of a programme to elicit and examine community preferences for health care in different contexts. Data were obtained from a group of predominantly Australian health care decision-makers. A short questionnaire contained six valuation questions and four demographic questions. The six valuation questions posed choices where equal health gains were to be allocated to different population groups based upon: age; sex; current health; socio-economic status; across time; and across different numbers of individuals. The results provide some evidence that respondents were prepared to discriminate between health gains derived in different contexts especially where health gains were to be allocated between groups of different health status and over time. Further research is planned and the possible implications for health policy, and in particular for resource allocation in health care, are briefly discussed. 相似文献