全文获取类型
收费全文 | 25887篇 |
免费 | 1628篇 |
国内免费 | 81篇 |
专业分类
耳鼻咽喉 | 179篇 |
儿科学 | 809篇 |
妇产科学 | 618篇 |
基础医学 | 3897篇 |
口腔科学 | 450篇 |
临床医学 | 3716篇 |
内科学 | 4693篇 |
皮肤病学 | 438篇 |
神经病学 | 2735篇 |
特种医学 | 600篇 |
外科学 | 2096篇 |
综合类 | 174篇 |
一般理论 | 26篇 |
预防医学 | 2995篇 |
眼科学 | 447篇 |
药学 | 1870篇 |
1篇 | |
中国医学 | 56篇 |
肿瘤学 | 1796篇 |
出版年
2024年 | 23篇 |
2023年 | 211篇 |
2022年 | 386篇 |
2021年 | 715篇 |
2020年 | 468篇 |
2019年 | 636篇 |
2018年 | 774篇 |
2017年 | 550篇 |
2016年 | 609篇 |
2015年 | 790篇 |
2014年 | 908篇 |
2013年 | 1454篇 |
2012年 | 2022篇 |
2011年 | 2175篇 |
2010年 | 1130篇 |
2009年 | 1061篇 |
2008年 | 1760篇 |
2007年 | 1827篇 |
2006年 | 1780篇 |
2005年 | 1664篇 |
2004年 | 1572篇 |
2003年 | 1443篇 |
2002年 | 1266篇 |
2001年 | 166篇 |
2000年 | 129篇 |
1999年 | 171篇 |
1998年 | 220篇 |
1997年 | 169篇 |
1996年 | 162篇 |
1995年 | 117篇 |
1994年 | 125篇 |
1993年 | 106篇 |
1992年 | 72篇 |
1991年 | 86篇 |
1990年 | 71篇 |
1989年 | 78篇 |
1988年 | 47篇 |
1987年 | 47篇 |
1986年 | 47篇 |
1985年 | 49篇 |
1984年 | 67篇 |
1983年 | 72篇 |
1982年 | 70篇 |
1981年 | 48篇 |
1980年 | 50篇 |
1979年 | 34篇 |
1978年 | 22篇 |
1977年 | 25篇 |
1976年 | 24篇 |
1974年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Cheryl M. Mccormick Priscilla Kehoe Sandra Kovacs 《International journal of developmental neuroscience》1998,16(3-4)
Repeated isolation of neonatal rats produces persistent changes in physiology and behavior. In Experiment 1, we examined changes in plasma corticosterone (CORT) levels as a possible mechanism for the effects of isolation. Pups that were isolated from their mother and the nest for 1 h per day on postnatal days (PND) 2–9 were compared to control litters of pups that were either nonhandled or handled but not isolated. On PND 2, compared to nonhandled pups, handled pups had elevated CORT levels that returned to baseline levels within 30 to 60 min of return to the home cage. No significant elevation of CORT levels were found in handled pups on PND 9. The CORT levels of isolated pups were over twice those of nonhandled pups on PND 2 and four times those of nonhandled pups on PND 9. In Experiment 2, we investigated whether the increased CORT release in response to isolation on PND 9 was the result of the pups treatment on the previous six days as against an effect of maturation. Plasma CORT levels were measured in rat pups that were either isolated, handled or nonhandled on PNDs 2–8 during the conditions of isolation, handling and nonhandling on PND 9. There were no differences among the groups in basal plasma levels of CORT. Handling on PND 9 did not result in elevated CORT levels in any of the groups. All three groups showed a significant increase in plasma CORT levels after isolation on PND 9. However, the CORT response to isolation of pups previously isolated on PND 2–8 were significantly higher than pups that were either handled or nonhandled on PNDs 2–8. Thus, daily episodes of isolation potentiate the hypothalamic-pituitary-adrenal response to stress. 相似文献
62.
Gail D'Onofrio Edward Bernstein Judith Bernstein Robert H. Woolard Phillip A. Brewer Sandra A. Craig Brian J. Zink 《Academic emergency medicine》1998,5(12):1200-1209
Abstract. Medical and social problems related to alcohol use are frequently seen in the ED. Often, the tempo of emergency medicine practice seems to preclude assessment beyond that required by the acute complaint. However, detection of ED patients with alcohol problems can occur using brief screening tools. This article was developed by members of the SAEM Substance Abuse Task Force, and describes screening tools that have been used successfully to identify atrisk and dependent drinkers. Their brevity, reproducibility, and accuracy vary somewhat, but screening can be realistically performed in the busy ED setting. The early detection of patients with alcohol problems would provide the opportunity for early intervention, and may reduce subsequent morbidity and mortality in this patient population. 相似文献
63.
64.
Evaluating the clinical nurse specialist. A review 总被引:7,自引:0,他引:7
This paper reviews evaluative studies on the role of clinical nurse specialists and aims to describe and categorise research according to the methods used. By using the structure, process and outcome framework a clear pattern of research development and evidence emerges. It appears that significant benefits accrue for patients from the contribution of nurse specialists, but more experimental studies with combined methods should now be applied to this area. 相似文献
65.
Sandra De sa Souza Christopher Lobo Promad Sarode 《Indian journal of otolaryngology and head and neck surgery》1991,43(4):180-185
Two hundred and eighty five patients presenting with profound bilateral sensorineural hearing loss from 1987 to 1989, were
subjected to a detailed history, pure tone audiogram, aided audiogram, Brain Stem Evoked Response Audiometry, Electrocochleography,
Cochlear Nerve Test, and Tomograms of the temporal bones. All the data collected was subsequently analysed. 相似文献
66.
67.
Steven M Kawut Darren B Taichman Vivek N Ahya Sandra Kaplan Christine L Archer-Chicko Stephen E Kimmel Harold I Palevsky 《Liver transplantation》2005,11(9):1107-1111
It is not known whether patients with pulmonary arterial hypertension associated with portal hypertension (portopulmonary hypertension (PPHTN) have different disease characteristics from those of patients with other forms of pulmonary arterial hypertension. We performed a retrospective cohort study of patients with PPHTN and patients with pulmonary arterial hypertension that was idiopathic, familial, or associated with anorexigen use (IPAH) to determine whether hemodynamics or survival were different between these groups. We included consecutive patients who underwent initial pulmonary artery catheterization and vasodilator testing at our center between January 1997 and May 2001 and who were followed until January 2004. Patients with PPHTN (N = 13) had a higher cardiac index and lower pulmonary vascular resistance than patients with IPAH (N = 33) (P < or = 0.001). Right atrial pressure and pulmonary artery pressure were similar between the groups. Patients with PPHTN had a higher risk of death in multivariate analysis (hazard ratio: [HR] = 2.8, 95% CI 1.04-7.4; P = 0.04). These findings were not affected by adjustment for differences in laboratory values, hemodynamics, or therapy. In conclusion, patients with PPHTN have a higher risk of death than that of patients with IPAH, despite having a higher cardiac index and lower pulmonary vascular resistance. Future studies of the specific mechanisms of and therapy for pulmonary arterial hypertension should focus on the distinctions between the different forms of this disease. 相似文献
68.
John Hart Raksha Anand Sandra Zoccoli Mandy Maguire Jacque Gamino Gail Tillman Richard King Michael A Kraut 《Journal of the International Neuropsychological Society》2007,13(5):865-880
Semantic memory is described as the storage of knowledge, concepts, and information that is common and relatively consistent across individuals (e.g., memory of what is a cup). These memories are stored in multiple sensorimotor modalities and cognitive systems throughout the brain (e.g., how a cup is held and manipulated, the texture of a cup's surface, its shape, its function, that is related to beverages such as coffee, and so on). Our ability to engage in purposeful interactions with our environment is dependent on the ability to understand the meaning and significance of the objects and actions around us that are stored in semantic memory. Theories of the neural basis of the semantic memory of objects have produced sophisticated models that have incorporated to varying degrees the results of cognitive and neural investigations. The models are grouped into those that are (1) cognitive models, where the neural data are used to reveal dissociations in semantic memory after a brain lesion occurs; (2) models that incorporate both cognitive and neuroanatomical information; and (3) models that use cognitive, neuroanatomic, and neurophysiological data. This review highlights the advances and issues that have emerged from these models and points to future directions that provide opportunities to extend these models. The models of object memory generally describe how category and/or feature representations encode for object memory, and the semantic operations engaged in object processing. The incorporation of data derived from multiple modalities of investigation can lead to detailed neural specifications of semantic memory organization. The addition of neurophysiological data can potentially provide further elaboration of models to include semantic neural mechanisms. Future directions should incorporate available and newly developed techniques to better inform the neural underpinning of semantic memory models. 相似文献
69.
Pilot study to enhance HIV care using needle exchange-based health services for out-of-treatment injecting drug users 总被引:2,自引:0,他引:2
Altice Frederick L. Springer Sandra Buitrago Marta Hunt David P. Friedland Gerald H. 《Journal of urban health》2003,80(3):416-427
The introduction of highly active antiretroviral therapy (HAART) has resulted in marked reductions in mortality and acquired
immunodeficiency syndrome (AIDS) incidence across all risk groups; however, the proportionate decrease among injecting drug
users (IDUs) has been less impressive. Much of the disparity in benefit to IDUs has been a consequence of decreased access
to and receipt of potent antiretroviral combinations. Strategies to increase access to and utilization of HAART have included
entry into drug treatment and abstinence. Unfortunately, as few as 15%–20% of active drug users in the United States, and
in many other countries, are in drug treatment at any one time. We report a pilot project among out-of-drug treatment IDUs
infected with human immunodeficiency virus (HIV); HIV therapy was successfully provided to active heroin injectors using the
Community Health Care Van (CHCV) at sites of needle exchange. Subjects were willing to initiate, but were not receiving, recommended
HIV therapy and were not interested in formal drug treatment. Antiretroviral therapy regimens were selected and linked to
heroin injection timing. Weekly visits were scheduled by CHCV staff to assess adverse side effects and encourage adherence.
Of the 13 participants, the mean baseline HIV-1 RNA level and CD4 lymphocyte count were 162,369 (log 5.21) copies per milliliter
and 265 cells per milliliter, respectively. By 6 months, the proportion whose HIV-1 RNA was below the limits of detection
(<400 copies/mL) was 85% (N=11); 77% (N=10) had nondetectable levels by 9 months. By 12 months, 54% (N=7) had a persistently
nondetectable viral load, and the net increase in CD4 lymphocyte count was 150 cells per milliliter. As an additional and
unintended benefit of this pilot project, 9 (69%) subjects chose to enter drug treatment after achieving a nondetectable viral
load. Entry into drug treatment was associated with durability of viral suppression. This small pilot study suggests that
health services based on needle exchange may enhance access to HAART among out-of-treatment HIV-infected IDUs. In addition,
it demonstrates that this population can benefit from this therapy with the support of a nontraditional, community-based health
intervention. 相似文献
70.
The spatial and temporal pattern of expression of the protein products of immediate early genes (IEGs) c-fos, fos B, and egr-1 were mapped in medial preoptic area (MPOA) and ventral bed nucleus of stria terminalis (VBST) during maternal behavior in rats. Immunocytochemical analysis indicated significant increases in the number of cells expressing c-Fos after 2 h of pup exposure, while Fos B levels showed a delayed response, reaching maximal levels after 6 h. 相似文献