全文获取类型
收费全文 | 2396995篇 |
免费 | 174945篇 |
国内免费 | 4644篇 |
专业分类
耳鼻咽喉 | 33202篇 |
儿科学 | 78982篇 |
妇产科学 | 67036篇 |
基础医学 | 340374篇 |
口腔科学 | 66528篇 |
临床医学 | 212971篇 |
内科学 | 465846篇 |
皮肤病学 | 56244篇 |
神经病学 | 193240篇 |
特种医学 | 94360篇 |
外国民族医学 | 688篇 |
外科学 | 361881篇 |
综合类 | 50654篇 |
现状与发展 | 3篇 |
一般理论 | 738篇 |
预防医学 | 177321篇 |
眼科学 | 55110篇 |
药学 | 178430篇 |
8篇 | |
中国医学 | 5722篇 |
肿瘤学 | 137246篇 |
出版年
2021年 | 17672篇 |
2019年 | 18514篇 |
2018年 | 27185篇 |
2017年 | 21085篇 |
2016年 | 24298篇 |
2015年 | 27125篇 |
2014年 | 36958篇 |
2013年 | 54763篇 |
2012年 | 75051篇 |
2011年 | 78915篇 |
2010年 | 46566篇 |
2009年 | 43622篇 |
2008年 | 73394篇 |
2007年 | 78375篇 |
2006年 | 79387篇 |
2005年 | 76934篇 |
2004年 | 73493篇 |
2003年 | 70734篇 |
2002年 | 68271篇 |
2001年 | 121266篇 |
2000年 | 124339篇 |
1999年 | 103797篇 |
1998年 | 27906篇 |
1997年 | 24907篇 |
1996年 | 24785篇 |
1995年 | 23328篇 |
1994年 | 21281篇 |
1993年 | 20008篇 |
1992年 | 77357篇 |
1991年 | 74107篇 |
1990年 | 71978篇 |
1989年 | 68850篇 |
1988年 | 62875篇 |
1987年 | 61262篇 |
1986年 | 57507篇 |
1985年 | 54443篇 |
1984年 | 40654篇 |
1983年 | 34267篇 |
1982年 | 20057篇 |
1979年 | 36140篇 |
1978年 | 25046篇 |
1977年 | 21495篇 |
1976年 | 19535篇 |
1975年 | 21139篇 |
1974年 | 24978篇 |
1973年 | 24085篇 |
1972年 | 22887篇 |
1971年 | 21114篇 |
1970年 | 19755篇 |
1969年 | 18696篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
Y.R. Song B. Wu Y.T. Yang J. Chen L.J. Zhang Z.W. Zhang H.Y. Shi C.L. Huang J.X. Pan P. Xie 《Brazilian journal of medical and biological research》2015,48(11):973-982
Bipolar disorder (BD) is a common psychiatric mood disorder affecting more than 1-2%
of the general population of different European countries. Unfortunately, there is no
objective laboratory-based test to aid BD diagnosis or monitor its progression, and
little is known about the molecular basis of BD. Here, we performed a comparative
proteomic study to identify differentially expressed plasma proteins in various BD
mood states (depressed BD, manic BD, and euthymic BD) relative to healthy controls. A
total of 10 euthymic BD, 20 depressed BD, 15 manic BD, and 20 demographically matched
healthy control subjects were recruited. Seven high-abundance proteins were
immunodepleted in plasma samples from the 4 experimental groups, which were then
subjected to proteome-wide expression profiling by two-dimensional electrophoresis
and matrix-assisted laser desorption/ionization-time-of-flight/time-of-flight tandem
mass spectrometry. Proteomic results were validated by immunoblotting and
bioinformatically analyzed using MetaCore. From a total of 32 proteins identified
with 1.5-fold changes in expression compared with healthy controls, 16 proteins were
perturbed in BD independent of mood state, while 16 proteins were specifically
associated with particular BD mood states. Two mood-independent differential
proteins, apolipoprotein (Apo) A1 and Apo L1, suggest that BD pathophysiology may be
associated with early perturbations in lipid metabolism. Moreover, down-regulation of
one mood-dependent protein, carbonic anhydrase 1 (CA-1), suggests it may be involved
in the pathophysiology of depressive episodes in BD. Thus, BD pathophysiology may be
associated with early perturbations in lipid metabolism that are independent of mood
state, while CA-1 may be involved in the pathophysiology of depressive episodes. 相似文献
62.
63.
Improvement in Tricuspid Annular Plane Systolic Excursion with Pulmonary Hypertension Therapy in Pediatric Patients 下载免费PDF全文
64.
O. Ieromina C. J. M. Musters P. M. Bodegom W. J. G. M. Peijnenburg M. G. Vijver 《Ecotoxicology (London, England)》2016,25(6):1170-1180
Analyzing functional species’ characteristics (species traits) that represent physiological, life history and morphological characteristics of species help understanding the impacts of various stressors on aquatic communities at field conditions. This research aimed to study the combined effects of pesticides and other environmental factors (temperature, dissolved oxygen, dissolved organic carbon, floating macrophytes cover, phosphate, nitrite, and nitrate) on the trait modality distribution of aquatic macrofauna communities. To this purpose, a field inventory was performed in a flower bulb growing area of the Netherlands with significant variation in pesticides pressures. Macrofauna community composition, water chemistry parameters and pesticide concentrations in ditches next to flower bulb fields were determined. Trait modalities of nine traits (feeding mode, respiration mode, locomotion type, resistance form, reproduction mode, life stage, voltinism, saprobity, maximum body size) likely to indicate pesticides impacts were analyzed. According to a redundancy analysis, phosphate -and not pesticides- constituted the main factor structuring the trait modality distribution of aquatic macrofauna. The functional composition could be ascribed for 2–4 % to pesticides, and for 3–11 % to phosphate. The lack of trait responses to pesticides may indicate that species may have used alternative strategies to adapt to ambient pesticides stress. Biomass of animals exhibiting trait modalities related to feeding by predation and grazing, presence of diapause form or dormancy, reproduction by free clutches and ovoviviparity, life stage of larvae and pupa, was negatively correlated to the concentration of phosphate. Hence, despite the high pesticide pollution in the area, variation in nutrient-related stressors seems to be the dominant driver of the functional composition of aquatic macrofauna assembly in agricultural ditches. 相似文献
65.
66.
67.
68.
69.
Danielle E Whittier Elizabeth J Samelson Marian T Hannan Lauren A Burt David A Hanley Emmanuel Biver Pawel Szulc Elisabeth Sornay-Rendu Blandine Merle Roland Chapurlat Eric Lespessailles Andy Kin On Wong David Goltzman Sundeep Khosla Serge Ferrari Mary L Bouxsein Douglas P Kiel Steven K Boyd 《Journal of bone and mineral research》2022,37(3):428-439
Prevalence of osteoporosis is more than 50% in older adults, yet current clinical methods for diagnosis that rely on areal bone mineral density (aBMD) fail to detect most individuals who have a fragility fracture. Bone fragility can manifest in different forms, and a “one-size-fits-all” approach to diagnosis and management of osteoporosis may not be suitable. High-resolution peripheral quantitative computed tomography (HR-pQCT) provides additive information by capturing information about volumetric density and microarchitecture, but interpretation is challenging because of the complex interactions between the numerous properties measured. In this study, we propose that there are common combinations of bone properties, referred to as phenotypes, that are predisposed to different levels of fracture risk. Using HR-pQCT data from a multinational cohort (n = 5873, 71% female) between 40 and 96 years of age, we employed fuzzy c-means clustering, an unsupervised machine-learning method, to identify phenotypes of bone microarchitecture. Three clusters were identified, and using partial correlation analysis of HR-pQCT parameters, we characterized the clusters as low density, low volume, and healthy bone phenotypes. Most males were associated with the healthy bone phenotype, whereas females were more often associated with the low volume or low density bone phenotypes. Each phenotype had a significantly different cumulative hazard of major osteoporotic fracture (MOF) and of any incident osteoporotic fracture (p < 0.05). After adjustment for covariates (cohort, sex, and age), the low density followed by the low volume phenotype had the highest association with MOF (hazard ratio = 2.96 and 2.35, respectively), and significant associations were maintained when additionally adjusted for femoral neck aBMD (hazard ratio = 1.69 and 1.90, respectively). Further, within each phenotype, different imaging biomarkers of fracture were identified. These findings suggest that osteoporotic fracture risk is associated with bone phenotypes that capture key features of bone deterioration that are not distinguishable by aBMD. © 2021 American Society for Bone and Mineral Research (ASBMR). 相似文献
70.
C.Z. Simonsen S. Schnenberger P.L. Hendn A.J. Yoo L. Uhlmann A. Rentzos J. Bsel J. Valentin M. Rasmussen 《AJNR. American journal of neuroradiology》2020,41(12):2298
BACKGROUND AND PURPOSE:Endovascular therapy for acute ischemic stroke is often performed with the patient under conscious sedation. Emergent conversion from conscious sedation to general anesthesia is sometimes necessary. The aim of this study was to assess the functional outcome in converted patients compared with patients who remained in conscious sedation and to identify predictors associated with the risk of conversion.MATERIALS AND METHODS:Data from 368 patients, included in 3 trials randomizing between conscious sedation and general anesthesia before endovascular therapy (SIESTA, ANSTROKE, and GOLIATH) constituted the study cohort. Twenty-one (11%) of 185 patients randomized to conscious sedation were emergently converted to general anesthesia.RESULTS:Absence of hyperlipidemia seemed to be the strongest predictor of conversion to general anesthesia, albeit a weak predictor (area under curve = 0.62). Sex, hypertension, diabetes, smoking status, atrial fibrillation, blood pressure, size of the infarct, and level and side of the occlusion were not significantly associated with conversion to general anesthesia. Neither age (mean age, 71.3 ± 13.8 years for conscious sedation versus 71.6 ± 12.3 years for converters, P = .58) nor severity of stroke (mean NIHSS score, 17 ± 4 versus 18 ± 4, respectively, P = .27) were significantly different between converters and those who tolerated conscious sedation. The converters had significantly worse outcome with a common odds ratio of 2.67 (P = .015) for a shift toward a higher mRS score compared with the patients remaining in the conscious sedation group.CONCLUSIONS:Patients undergoing conversion had significantly worse outcome compared with patients remaining in conscious sedation. No factor was identified that predicted conversion from conscious sedation to general anesthesia.Five studies published in 2015 proved the efficacy of endovascular therapy (EVT) for acute ischemic stroke caused by a large-vessel occlusion.1 However, numerous questions remain regarding how to best deliver this treatment, including evaluation of the optimal thrombectomy technique,2 the most effective method of patient triage,3 or whether EVT should be performed with the patient under either general anesthesia (GA) or conscious sedation (CS).Observational studies have suggested that EVT with the patient under CS is associated with better neurologic outcome and lower mortality compared with GA.4 However, 3 randomized trials reported similar outcomes between CS and GA.5-7 Proposed benefits of CS include stable hemodynamics, clinical monitoring, and a potentially shorter procedure. The disadvantages are an unprotected airway and patient movement, which sometimes may require emergent conversion to GA. Patients who need conversion might be sicker (larger strokes, more medical complications), but the conversion procedure itself may also have a potentially deleterious influence on outcome due to the emergent anesthetic induction, associated hypotension, and added time delay before reperfusion.Although most patients can be treated under the less complex CS, it is of interest to identify factors that can predict the risk of conversion and hence the requirement for GA. We undertook a detailed analysis of the patients who were converted from CS to GA in our individual patient data base from the 3 randomized trials to examine the outcome of the converted patients compared with patients who remained in CS. We also aimed to identify possible predictors associated with a need for GA with EVT. 相似文献