全文获取类型
收费全文 | 35821篇 |
免费 | 2197篇 |
国内免费 | 103篇 |
专业分类
耳鼻咽喉 | 331篇 |
儿科学 | 1090篇 |
妇产科学 | 895篇 |
基础医学 | 5061篇 |
口腔科学 | 679篇 |
临床医学 | 4247篇 |
内科学 | 7455篇 |
皮肤病学 | 778篇 |
神经病学 | 3424篇 |
特种医学 | 767篇 |
外科学 | 3576篇 |
综合类 | 280篇 |
一般理论 | 27篇 |
预防医学 | 3973篇 |
眼科学 | 629篇 |
药学 | 2510篇 |
1篇 | |
中国医学 | 120篇 |
肿瘤学 | 2278篇 |
出版年
2023年 | 259篇 |
2022年 | 286篇 |
2021年 | 900篇 |
2020年 | 574篇 |
2019年 | 910篇 |
2018年 | 1207篇 |
2017年 | 778篇 |
2016年 | 853篇 |
2015年 | 999篇 |
2014年 | 1182篇 |
2013年 | 1833篇 |
2012年 | 2646篇 |
2011年 | 2892篇 |
2010年 | 1503篇 |
2009年 | 1309篇 |
2008年 | 2356篇 |
2007年 | 2443篇 |
2006年 | 2459篇 |
2005年 | 2304篇 |
2004年 | 2158篇 |
2003年 | 1994篇 |
2002年 | 1760篇 |
2001年 | 526篇 |
2000年 | 572篇 |
1999年 | 481篇 |
1998年 | 266篇 |
1997年 | 203篇 |
1996年 | 184篇 |
1995年 | 131篇 |
1994年 | 147篇 |
1993年 | 128篇 |
1992年 | 176篇 |
1991年 | 177篇 |
1990年 | 164篇 |
1989年 | 146篇 |
1988年 | 102篇 |
1987年 | 106篇 |
1986年 | 109篇 |
1985年 | 94篇 |
1984年 | 91篇 |
1983年 | 97篇 |
1982年 | 80篇 |
1981年 | 59篇 |
1980年 | 64篇 |
1979年 | 49篇 |
1978年 | 39篇 |
1977年 | 37篇 |
1976年 | 38篇 |
1974年 | 35篇 |
1973年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
42.
Sandra Fabian Heike Hesse Roland Grassme Ingo Bradl Annette Bernsdorf 《Pathophysiology》2005,12(4):281-287
The results of most reported studies show differences between the muscular activity of low back pain patients and healthy subjects, but the focus has usually been on trunk muscles only, and they have not involved work-related tests or exercises. The reintegration of chronic low back pain patients to job market is a common problem. Therefore assessment systems like the functional capacity evaluation (FCE) according to Isernhagen [S.J. Isernhagen, Work Injury: Management and Prevention, Aspen Publishers Inc., Gaithersburg, MD, 1988] are often used tools to determine the physical abilities and deficits of long-time incapacitated persons. The aim of the present study was to compare the healthy persons and chronic low back pain patients in performing a FCE-test and to analyse their muscular activation and motion patterns. The results indicate differences in the activation patterns of the groups in the test task “floor to waist lift” common in many occupations. 相似文献
43.
44.
Sergi Sastre Francisco Maculé Sandra Lasurt Josep-María Segur Lluis Lozano Montse Nuñez Santiago Suso 《European journal of orthopaedic surgery & traumatology : orthopedie traumatologie》2007,17(4):393-397
Five patients with idiopathic transient osteoporosis were examined. Bone scanning and MRI was helpful in the diagnosis to differentiate of necrosis and all patients recovered completely with conservative and symptomatic treatment. There was no history of trauma in all patients. MRI was realized previously in all cases to confirm the diagnosis and after the resolution of symptomathology. 相似文献
45.
Sandra Urdaneta Hartmann Brian Wigdahl Elizabeth B Neely Cheston M Berlin Cara-Lynne Schengrund Hung-Mo Lin Mary K Howett 《Journal of human lactation》2006,22(1):61-74
Reduction of transmission of human immunodeficiency virus type 1 (HIV-1) through human milk is needed. Alkyl sulfates such as sodium dodecyl sulfate (SDS) are microbicidal against HIV-1 at low concentrations, have little to no toxicity, and are inexpensive. The authors have reported that treatment of HIV-1-infected human milk with < or = 1% (10 mg/mL) SDS for 10 minutes inactivates cell-free and cell-associated virus. The SDS can be removed with a commercially available resin after treatment without recovery of viral infectivity. In this article, the authors report results of selective biochemical analyses (ie, protein, immunoglobulins, lipids, cells, and electrolytes) of human milk subjected to SDS treatment and removal. The SDS treatment or removal had no significant effects on the milk components studied. Therefore, the use of alkyl sulfate microbicides to treat milk from HIV-1-positive women may be a simple, practical, and nutritionally sound way to prevent or reduce transmission of HIV-1 while still feeding with mother's own milk. 相似文献
46.
Plasma levels and vascular effects of vasopressin in patients undergoing coronary artery bypass grafting. 总被引:1,自引:0,他引:1
Susana Novella Ana Cristina Martínez Rosa María Pagán Medardo Hernández Albino García-Sacristán Angel González-Pinto José María González-Santos Sara Benedito 《European journal of cardio-thoracic surgery》2007,32(1):69-76
OBJECTIVE: Recent studies have suggested that endogenous vasopressin (AVP) acts as a spasmogen during coronary artery bypass grafting (CABG). Given that AVP could induce vasospasm in the grafted vessel, we assessed the release of this peptide during and after CABG, and explored ways of counteracting its contractile effect on the internal mammary artery (IMA). METHODS: Plasma levels of AVP were determined by radioimmunoassay in 16 patients before, during and after CABG. Using isometric force recording techniques, we also investigated the mechanisms involved in the contractile effect of AVP in ring preparations of IMA specimens taken from 95 patients. RESULTS: Plasma AVP levels peaked after the start of cardiopulmonary bypass (CPB) and correlated well with serum osmolality (Pearson's r=0.9490; P<0.0001; n=16). An inverse correlation was observed between plasma AVP levels recorded at this stage and the maximal contraction induced in vitro by AVP in vascular rings from the same patients (Pearson's r=-0.6968; P<0.01; n=16). No change in the AVP response was produced by endothelium removal, exposure to the NO precursor (3 x 10(-4)M L-arginine), inhibition of nitric oxide (NO) synthase (3 x 10(-5) M L-NAME) or soluble guanylate cyclase (3 x 10(-6) M 1H-[1,2,4]oxadiazol [4,3,-alpha]quinoxalin-1-one (ODQ)), removal of the superoxide anion (100 U/ml superoxide dismutase (SOD) plus 1200 U/ml catalase) or hydroxyl radical (10(-4) M deferoxamine), or specific alpha1 - (10(-6) M prazosin) or endothelin (10(-5) M bosentan) receptor antagonism. In contrast, adenylate cyclase activation (3 x 10(-8) M forskolin) reduced the contractile response to AVP, while prostanoid synthesis (3 x 10(-6) M indomethacin) inhibition and blockade of Ca2+ -activated potassium channels (KCa) (10(-3) M tetraethylammonium (TEA)) enhanced AVP contraction. Age, gender and smoking also modified the AVP response. CONCLUSION: Our findings suggest a role for AVP as a modulator of vascular tone in human IMA. The effect of AVP is dependent on prostanoids and Ca2+ -activated K+ channels, so its dysfunction in pathophysiological cardiovascular processes could mean that AVP, among other factors, produces vasospasm in IMA grafts. 相似文献
47.
Blindsight is a visual phenomenon whereby hemianopic patients are able to process visual information in their blind visual field without awareness. Previous research demonstrating the existence of blindsight in hemianopic patients has been criticized for the nature of the paradigms used, for the presence of methodological artifacts, and for the possibility that spared islands of visual cortex may have sustained the phenomenon because the patients generally had small circumscribed lesions. To respond to these criticisms, the authors have been investigating for several years now residual visual abilities in the blind field of hemispherectomized patients in whom a whole cerebral hemisphere has been removed or disconnected from the rest of the brain. These patients have offered a unique opportunity to establish the existence of blindsight and to investigate its underlying neuronal mechanisms because in these cases, spared islands of visual cortex cannot be evoked to explain the presence of visual abilities in the blind field. In addition, the authors have been using precise behavioral paradigms, strict control for potential methodological artifacts such as light scatter, fixation, criterion effects, and macular sparing, and they have utilized new neuroimaging techniques such as diffusion tensor imaging tractography to enhance their understanding of the phenomenon. The following article is a review of their research on the involvement of the superior colliculi in blindsight in hemispherectomized patients. . 相似文献
48.
Sandra E. File 《Human psychopharmacology》1987,2(3):151-158
The clinical efficacy of the benzodiazepines in reducing anxiety is widely accepted. However, the search for novel anxiolytics continues, motivated by the hope of finding a non-sedative anxiolytic. This article reviews the pre-clinical evidence for new compounds as it relates both to their anxiolytic actions in animal tests and to their sedative potential. Drugs acting at sites on the GABA-benzodiazepine receptor complex are discussed, as well as the potential importance of aminergic and peptidergic pathways. 相似文献
49.
Marcela Hernández Hoyos Piotr Orłowski Ewa Piątkowska-Janko Piotr Bogorodzki Maciej Orkisz 《International journal of computer assisted radiology and surgery》2006,1(1):51-61
The accuracy of 2D phase contrast (PC) magnetic resonance angiography (MRA) depends on the alignment between the vessels and
the imaging plane. PC MRA imaging of blood flow is challenging when the flow in several vessels is to be evaluated with one
acquisition. For this purpose, semi-automatic determination of the plane most perpendicular to several vessels is proposed
based on centerlines extracted from 3D MRA. Arterial centerlines are extracted from 3D MRA based on iterative estimation-prediction,
multi-scale analysis of image moments, and a second-order shape model. The optimal plane is determined by minimizing misalignment
between its normal vector and the centerlines’ tangent vectors. The method was evaluated on a phantom and on 35 patients,
by seeking the optimal plane for cerebral blood flow quantification simultaneously in internal carotids and vertebral arteries.
In the phantom, difference of orientation and of height between known and calculated planes was 1.2° and 2.5 mm, respectively.
In the patients, all but one centerline were correctly extracted and the misalignment of the plane was within 12° per artery.
Semi-automatic centerline extraction simplifies and automates determination of the plane orthogonal to one vessel, thereby
permitting automatic simultaneous minimization of the misalignment with several vessels in PC MRA. 相似文献
50.
Sandra V Navarra 《Nephrology, dialysis, transplantation》2006,21(3):579-581
Systemic lupus erythematosus (SLE) is a complex disease whichhas posed a continuing challenge to scientists and cliniciansof diverse areas of specialization. It serves as a model forthe study of the mechanisms of autoimmunityprovidingan important basis for the development of novel targeted therapiesin lupus and related conditions. The pathophysiology of SLE stems from the abnormal clearanceof apoptotic cells and/or endothelial activation. Material fromdying cells such as apoptotic blebs that are not efficientlyremoved may act as antigenic stimuli and lead to the developmentof autoantibodies with consequent formation of immune complexesand an inflammatory response in a variety of organ systems [1].This 相似文献