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   3074篇
  免费   161篇
  国内免费   4篇
耳鼻咽喉   34篇
儿科学   116篇
妇产科学   109篇
基础医学   377篇
口腔科学   36篇
临床医学   160篇
内科学   722篇
皮肤病学   75篇
神经病学   267篇
特种医学   216篇
外科学   470篇
综合类   82篇
一般理论   1篇
预防医学   109篇
眼科学   126篇
药学   209篇
中国医学   5篇
肿瘤学   125篇
  2023年   28篇
  2022年   40篇
  2021年   77篇
  2020年   34篇
  2019年   57篇
  2018年   92篇
  2017年   62篇
  2016年   73篇
  2015年   89篇
  2014年   110篇
  2013年   120篇
  2012年   219篇
  2011年   209篇
  2010年   105篇
  2009年   95篇
  2008年   147篇
  2007年   161篇
  2006年   162篇
  2005年   128篇
  2004年   145篇
  2003年   115篇
  2002年   94篇
  2001年   106篇
  2000年   85篇
  1999年   60篇
  1998年   29篇
  1997年   17篇
  1996年   15篇
  1995年   11篇
  1993年   12篇
  1992年   43篇
  1991年   34篇
  1990年   38篇
  1989年   33篇
  1988年   27篇
  1987年   31篇
  1986年   34篇
  1985年   25篇
  1984年   29篇
  1983年   20篇
  1982年   19篇
  1979年   14篇
  1978年   16篇
  1977年   15篇
  1975年   13篇
  1974年   13篇
  1973年   13篇
  1970年   12篇
  1968年   13篇
  1967年   13篇
排序方式: 共有3239条查询结果,搜索用时 31 毫秒
81.
82.
83.
Small supernumerary marker chromosomes (sSMC) are chromosomal fragments difficult to characterize genomically. Here, we detail a proband with schizoaffective disorder and a mother with bipolar disorder with psychotic features who present with a marker chromosome that segregates with disease. We explored the architecture of this marker and investigated its temporal origin. Array comparative genomic hybridization (aCGH) analysis revealed three duplications and three triplications that spanned the short arm of chromosome 9, suggestive of a chromoanasynthesis‐like event. Segregation of marker genotypes, phased using sSMC mosaicism in the mother, provided evidence that it was generated during a germline‐level event in the proband's maternal grandmother. Whole‐genome sequencing (WGS) was performed to resolve the structure and junctions of the chromosomal fragments, revealing further complexities. While structural variations have been previously associated with neuropsychiatric disorders and marker chromosomes, here we detail the precise architecture, human life‐cycle genesis, and propose a DNA replicative/repair mechanism underlying formation.  相似文献   
84.
Cryptococcus neoformans is an opportunistic pathogen in AIDS patients causing disseminated disease and lethal meningitis after inhalation of acapsular or sparsely encapsulated yeast cells. In this study we have investigated whether a recently described family of primitive opsonins, termed collectins, contribute to innate resistance against C. neoformans. The pulmonary surfactant proteins SP-A and SP-D as well as the serum collectins mannose-binding protein and CL-43 bound in a calcium-dependent manner to acapsular C. neoformans in vitro. Binding was concentration dependent and abolished by competition with defined mono- and oligosaccharides. In contrast, no binding of the collectins was observed with the encapsulated form of the yeast. Furthermore, binding of purified collectin SP-D, but not SP-A, mannose-binding protein, or CL-43, led to a concentration-dependent agglutination of acapsular C. neoformans. These data indicate that collectins recognize carbohydrate structures in the cell wall of an initial infectious form of C. neoformans and may play a role in early antifungal defenses in the lung.  相似文献   
85.
The masticatory apparatus has been the focus of many studies in comparative anatomy—especially analyses of skulls and teeth, but also of the mandibular adductor muscles which are responsible for the production of bite force and the movements of the mandible during food processing and transport. The fiber architecture of these muscles has been correlated to specific diets (e.g., prey size in felids) and modes of foraging (e.g., tree gouging in marmosets). Despite the well-elucidated functional implications of this architecture, little is known about its ontogeny. To characterize age-related myological changes, we studied the masticatory muscles in a large (n = 33) intraspecific sample of a small, Malagasy primate, Microcebus murinus including neonatal through geriatric individuals. We removed each of the mandibular adductors and recorded its mass as well as other linear measurements. We then chemically dissected each muscle to study its architecture—fascicle length and physiological cross-sectional area (PCSA) which relate to stretch (gape) and force capabilities, respectively. We observed PCSA and muscle mass to increase rapidly and plateau in adulthood through senescence. Fascicle lengths remained relatively constant once maximal length was reached, which occurred early in life, suggesting that subsequent changes in PCSA are driven by changes in muscle mass. Quadratic curvilinear models of each of the architectural variables of all adductors combined as well as individual muscles regressed against age were all significant. Anat Rec, 303:1364–1373, 2020. © 2019 American Association for Anatomy  相似文献   
86.
Autologous or allogeneic SCT with conventional conditioning (chemotherapy with or without irradiation) has emerged as an effective and potentially curative therapy in patients with hematologic malignancies and in other selected solid tumors; however, several patients experience significant early and delayed side effects, including long-term endocrine imbalance and infertility. In spite of several reproductive recovery and pregnancy reports published in the oncology literature, review of medical literature reveals a paucity of comparable information in the SCT field. We report here four cases of ovarian recovery in patients who received hormonal replacement therapy after diagnosis of primary ovarian failure due to high-dose chemotherapy and SCT.  相似文献   
87.
We assess for the mediation of the association between older person cognitive impairment and caregiver depressive symptoms through older person BPS and functional limitations, and whether the mediation varies by caregiver–older person relationship (spouse/adult child). Data for 1111 older person (aged 75+ with activity of daily living (ADL) limitation)–caregiver dyads from Singapore were used. The outcome variable was dichotomous (caregiver clinically significant depressive symptoms [CSDS]: yes/no) in the primary analysis and continuous (caregiver depressive symptoms score) in the sensitivity analysis. The causal steps approach assessed for the mediation of the association between older person cognitive impairment (yes/no) and the outcome variable through the two potential mediators. A bootstrapping approach calculated point estimates and confidence intervals (CIs) of the indirect (∼mediated) effects. Variation of the indirect effects by caregiver–older person relationship was also assessed. In the primary analysis, the causal steps approach supported older person BPS and functional limitations as mediators. The bootstrapping approach confirmed both as significant mediators, though BPS (indirect effect odds ratio (OR) 1.32 [95% bootstrap CI 1.19,1.48]; %mediation: 70.6%) was a stronger mediator than functional limitations (1.04 [1.01,1.11]; %mediation: 11.5%). Variation of the indirect effects by caregiver–older person relationship was not supported. Results of the sensitivity analysis confirmed these results. We conclude that while caring for an older person with cognitive impairment is detrimental for the caregiver's mood, management of associated BPS and functional limitations, especially the former, among such older persons may reduce depressive symptoms among their caregivers. Spouse as well as adult child caregivers benefit.  相似文献   
88.
89.

Objective  

To evaluate the role of 68Ga-labelled [1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid]-1-NaI3-Octreotide (68Ga-DOTA-NOC) whole body positron emission tomography-computed tomography (PET-CT) as a functional imaging approach for phaeochromocytoma and paraganglioma.  相似文献   
90.
We examined priming of visual search by repeated target location or color in two patients with left visual neglect and extinction, following strokes centered on the right inferior parietal lobe. Both patients, like the healthy controls we tested, showed intact priming, with performance speeded when either the location or color of a singleton target was repeated over successive trials in a standard search condition (Experiment 1). This was observed both from and to targets on the contralesional (left) side. Moreover, priming of search was still observed even when a return of fixation back to display-center was required between successive trials (Experiment 2). When briefer displays were used (Experiment 3), the patients often failed to detect left targets. This situation revealed an important dissociation: Whereas location priming only arose from preceding left targets that had been consciously detected, color priming (possibly arising within the intact ventral stream) did not depend on awareness of the preceding target. There was considerable color priming from missed targets. These findings demonstrate relatively intact priming of visual search by color and location in patients with right parietal damage, and also reveal that location priming may differ from color priming in requiring awareness.  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