全文获取类型
收费全文 | 1151篇 |
免费 | 118篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 23篇 |
儿科学 | 43篇 |
妇产科学 | 26篇 |
基础医学 | 163篇 |
口腔科学 | 6篇 |
临床医学 | 155篇 |
内科学 | 158篇 |
皮肤病学 | 15篇 |
神经病学 | 127篇 |
特种医学 | 27篇 |
外科学 | 167篇 |
综合类 | 9篇 |
一般理论 | 1篇 |
预防医学 | 156篇 |
眼科学 | 17篇 |
药学 | 91篇 |
肿瘤学 | 87篇 |
出版年
2024年 | 1篇 |
2023年 | 18篇 |
2022年 | 18篇 |
2021年 | 52篇 |
2020年 | 37篇 |
2019年 | 47篇 |
2018年 | 55篇 |
2017年 | 37篇 |
2016年 | 43篇 |
2015年 | 58篇 |
2014年 | 71篇 |
2013年 | 58篇 |
2012年 | 106篇 |
2011年 | 107篇 |
2010年 | 53篇 |
2009年 | 44篇 |
2008年 | 60篇 |
2007年 | 73篇 |
2006年 | 59篇 |
2005年 | 54篇 |
2004年 | 54篇 |
2003年 | 42篇 |
2002年 | 44篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 12篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有1271条查询结果,搜索用时 15 毫秒
1.
2.
3.
Distortion-product emissions and auditory sensitivity in human ears with normal hearing and cochlear hearing loss. 总被引:2,自引:0,他引:2
Distortion product emissions (DPEs) at 2f1-f2 frequencies were measured in 53 human ears; 21 of them exhibited cochlear hearing loss. DPEs were obtained as a function of stimulus level (DPE growth curves) at seven frequency regions between 707 Hz and 5656 Hz. Several distinctly different shapes or patterns of DPE growth curves were observed. These included single-segment monotonic growth curves with and without saturation at moderate and high stimulus levels, diphasic growth curves with nulls at moderate stimulus levels, and non-monotonic growth curves with negative slopes at high stimulus levels. Low-level, irregularly shaped segments were more frequent in normal-hearing ears, suggestive of normal low-level active nonlinearities from the outer-hair-cell subsystem. High-level, steeply sloped segments were frequent in hearing-impaired ears, suggestive of residual nonlinearities from a cochlear partition without functional outer hair cells. The stimulus level at which the DPE could just be distinguished from the noise floor, the DPE detection threshold, demonstrated moderate positive correlations (r's from 0.50 to 0.81) with auditory thresholds when all ears, both normal and impaired, were considered together. Those correlations were not strong enough to quantitatively predict auditory thresholds with any great accuracy. However, DPE thresholds were able to predict abnormal auditory sensitivity with some precision. DPE thresholds correctly predicted abnormal auditory sensitivity 79% of the time in the present study, and up to 96% of the time in previous studies. These results suggest that DPE thresholds may prove useful for hearing screening in cases where cooperation from the subject is limited or where corroboration of cochlear hearing loss is required. Different patterns of DPE growth curves suggest underlying micro-mechanical differences between ears, but the differential diagnostic value of those patterns remains to be determined. 相似文献
4.
Immunization reverses memory deficits without reducing brain Abeta burden in Alzheimer's disease model 总被引:13,自引:0,他引:13
Dodart JC Bales KR Gannon KS Greene SJ DeMattos RB Mathis C DeLong CA Wu S Wu X Holtzman DM Paul SM 《Nature neuroscience》2002,5(5):452-457
We have previously shown that chronic treatment with the monoclonal antibody m266, which is specific for amyloid beta-peptide (Abeta), increases plasma concentrations of Abeta and reduces Abeta burden in the PDAPP transgenic mouse model of Alzheimer's disease (AD). We now report that administration of m266 to PDAPP mice can rapidly reverse memory deficits in both an object recognition task and a holeboard learning and memory task, but without altering brain Abeta burden. We also found that an Abeta/antibody complex was present in both the plasma and the cerebrospinal fluid of m266-treated mice. Our data indicate that passive immunization with this anti-Abeta monoclonal antibody can very rapidly reverse memory impairment in certain learning and memory tasks in the PDAPP mouse model of AD, owing perhaps to enhanced peripheral clearance and (or) sequestration of a soluble brain Abeta species. 相似文献
5.
Allison J Geddes Heather E Angka Kimberley A Davies Boris Kablar 《Developmental dynamics》2006,235(8):2175-2184
The aim of our study was to assess the ability of brain-derived neurotrophic factor (BDNF) to rescue motor and sensory neurons from programmed cell death. It is clearly demonstrated that the administration of a single injection of a putative neurotrophic factor to mouse embryos in utero on embryonic day (E) 14.5 is sufficient to significantly reduce the death of motor neurons when assessed on E18.5. However, the trophic requirements of somatic neurons have not been unequivocally determined in a mammalian species in vivo. Indeed, the unexpectedly high numbers of surviving neurons observed in neurotrophin and tyrosine kinase receptor knockout mice are probably the consequence of functional redundancy between the neurotrophins and their receptors. We studied spinal cord and facial motor nucleus neurons and proprioceptive neurons in the dorsal root ganglion and mesencephalic nucleus. The action of BDNF was assessed in wild-type fetuses to gain insight into its ability to rescue neurons from naturally occurring programmed cell death. In addition, we used Myf5(-/-):MyoD(-/-) embryos, which completely lack skeletal musculature, to assess the ability of BDNF to rescue neurons from excessively occurring programmed cell death. We found that BDNF differentially rescued neurons from naturally vs. excessively occurring cell death and that its ability to do so varied among neuronal subpopulations. 相似文献
6.
Background
Relatives of BRCA1 and BRCA2 mutation carriers have long been proposed by epidemiological studies to have an increased risk of developing prostate cancer. In the Ashkenazi Jewish (AJ) population, the existence of 3 frequent founder mutations, 185delAG and 5382insC in BRCA1 and 6174delT in BRCA2 greatly facilitates screening for carriers. 相似文献7.
Tony Wawina-Bokalanga Bert Vanmechelen Valentine Lhermitte Joan Martí-Carreras Valentijn Vergote Fara Raymond Koundouno Joseph Akoi-Bor Ruth Thom Tom Tipton Kimberley Steeds Kita Balla Moussa Ablam Amento Lies Laenen Sophie Duraffour Martin Gabriel Paula Ruibal Yper Hall Mandy Kader-Kond Stephan Günther Guy Baele Cesar Muoz-Fontela Johan Van Weyenbergh Miles W. Carroll Piet Maes 《Emerging infectious diseases》2021,27(1):76
We investigated the genetic profiles of killer cell immunoglobulin-like receptors (KIRs) in Ebola virus–infected patients. We studied the relationship between KIR–human leukocyte antigen (HLA) combinations and the clinical outcomes of patients with Ebola virus disease (EVD). We genotyped KIRs and HLA class I alleles using DNA from uninfected controls, EVD survivors, and persons who died of EVD. The activating 2DS4–003 and inhibitory 2DL5 genes were significantly more common among persons who died of EVD; 2DL2 was more common among survivors. We used logistic regression analysis and Bayesian modeling to identify 2DL2, 2DL5, 2DS4–003, HLA-B-Bw4-Thr, and HLA-B-Bw4-Ile as probably having a significant relationship with disease outcome. Our findings highlight the importance of innate immune response against Ebola virus and show the association between KIRs and the clinical outcome of EVD. 相似文献
8.
Ari Whiteman Alice Wang Kelly McCain Betsy Gunnels Robin Toblin James Tseryuan Lee Carolyn Bridges Laura Reynolds Bhavini Patel Murthy Judy Qualters James A. Singleton Kimberley Fox Shannon Stokley LaTreace Harris Lynn Gibbs-Scharf Neetu Abad Kathryn A. Brookmeyer Susan Farrall Cassandra Pingali Anita Patel Ruth Link-Gelles Sharoda Dasgupta Radhika Gharpure Matthew D. Ritchey Kamil. E. Barbour 《MMWR. Morbidity and mortality weekly report》2021,70(19):725
9.
Nicholas A. Kimberley Susan M. Kirkpatrick James M. Watters 《Canadian journal of surgery》1996,39(4):312-316
Objective
To compare the effects of laparoscopic and open surgical procedures on postoperative strength and respiratory mechanics.Design
Prospective cohort study.Setting
Adult university hospital.Participants
Fifty-one women aged 21 to 62 years scheduled to undergo elective cholecystectomy or hysterectomy (or related procedures), otherwise in good health.Intervention
Open or laparoscopic cholecystectomy or hysterectomy (or related procedures).Main Outcome Measures
Maximum voluntary handgrip strength (HGS), forced vital capacity (VC), forced expiratory volume in 1 second (FEV1), and maximal inspiratory pressure (MIP) were each measured preoperatively and on the first postoperative morning. A visual analogue pain scale score was evaluated in relation to performance of the postoperative strength and respiratory measurements.Results
VC, FEV1 and MIP, but not HGS, were decreased after surgery. Postoperative VC, FEV1 and MIP were lower after open procedures than after laparoscopic procedures and after cholecystectomy than after hysterectomy (all p < 0.001). Pain scores were lower after laparoscopic than after open procedures (p < 0.005) and could account in part for differences in postoperative respiratory mechanics.Conclusions
Cholecystectomy and hysterectomy do not result in generalized muscle weakness, unlike more major abdominal procedures. Postoperative alterations in respiratory mechanics are related to the site of the surgery, the use of an open versus a laparoscopic approach and postoperative pain. 相似文献10.
Diego Nuñez Jr. M.D. John D. Wester M.D. Kimberley A. Lentz M.D. Marco A. Amendola M.D. 《Emergency radiology》1996,3(1):20-24
This study was performed to evaluate whether consecutive arterial phase and portal venous phase scans of the upper abdomen are contributory in the evaluation of the liver in patients with blunt abdominal trauma. The purpose of the study was to determine whether such dual acquisition using helical computed tomography (HCT) provides improved definition of injuries and significant information about the dynamics of posttraumatic hemorrhage.During a 10-month period, all patients referred for evaluation of blunt abdominal trauma were scanned using a dual phase imaging technique. Two consecutive and comparable scan clusters were programmed to study the upper abdomen, with a slice collimation of 10 mm and a 11 pitch. Intravenous contrast medium was delivered at a rate of 2 ml/sec for a total of 125 ml, with scan delays of 30 and 70 seconds (arterial and venous phases of hepatic enhancement).Thirty-two patients with hepatic lacerations were encountered, and the images from both acquisitions were compared and graded according to lesion conspicuity. The presence of contrast medium extravasation associated with parenchymal injuries was also recorded.In 23 (72%) of the 32 patients, the liver injuries were better defined in the portal venous phase, and in eight (25%) patients, the lesions were equally shown in both phases. In only one case, the lesion was better demonstrated in the arterial phase. Contrast medium extravasation was noted in two patients at the site of liver laceration. In three additional cases, contrast medium extravasation was also noted in associated splenic injuries. In all of these patients, the extravasation (bleeding laceration) was seen only in the images corresponding to the portal venous phase.Dual phase HCT of the upper abdomen does not provide significant additional information in the evaluation of patients with liver injuries resulting from blunt abdominal trauma. With a single scan cluster through the upper abdomen after a 70-second injection-scan delay, lesion definition is optimal, and vascular opacification remains adequate. 相似文献