全文获取类型
收费全文 | 9250篇 |
免费 | 1033篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 138篇 |
儿科学 | 475篇 |
妇产科学 | 185篇 |
基础医学 | 1335篇 |
口腔科学 | 179篇 |
临床医学 | 1076篇 |
内科学 | 1432篇 |
皮肤病学 | 115篇 |
神经病学 | 824篇 |
特种医学 | 400篇 |
外科学 | 1430篇 |
综合类 | 312篇 |
一般理论 | 8篇 |
预防医学 | 983篇 |
眼科学 | 240篇 |
药学 | 587篇 |
中国医学 | 28篇 |
肿瘤学 | 559篇 |
出版年
2021年 | 143篇 |
2019年 | 131篇 |
2018年 | 197篇 |
2017年 | 144篇 |
2016年 | 132篇 |
2015年 | 153篇 |
2014年 | 203篇 |
2013年 | 302篇 |
2012年 | 396篇 |
2011年 | 403篇 |
2010年 | 263篇 |
2009年 | 231篇 |
2008年 | 344篇 |
2007年 | 393篇 |
2006年 | 382篇 |
2005年 | 380篇 |
2004年 | 335篇 |
2003年 | 317篇 |
2002年 | 315篇 |
2001年 | 271篇 |
2000年 | 295篇 |
1999年 | 249篇 |
1998年 | 153篇 |
1997年 | 144篇 |
1996年 | 154篇 |
1995年 | 149篇 |
1994年 | 113篇 |
1993年 | 108篇 |
1992年 | 227篇 |
1991年 | 213篇 |
1990年 | 214篇 |
1989年 | 203篇 |
1988年 | 199篇 |
1987年 | 189篇 |
1986年 | 160篇 |
1985年 | 160篇 |
1984年 | 115篇 |
1983年 | 115篇 |
1981年 | 99篇 |
1980年 | 85篇 |
1979年 | 126篇 |
1978年 | 78篇 |
1977年 | 82篇 |
1976年 | 75篇 |
1975年 | 75篇 |
1974年 | 81篇 |
1973年 | 98篇 |
1972年 | 83篇 |
1971年 | 82篇 |
1970年 | 76篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Background: The Farnsworth D15 test is designed to categorise colour vision deficiency as severe or moderate. The level of difficulty of the test was set so that those who passed it should be able to recognise surface colour codes, such as those used for electrical wiring. The test is widely used to provide advice to patients with abnormal colour vision and is often used for occupational selection when reliable recognition of surface colour codes is required. However, there has been only one previous study of the correlation between performance at the D15 test and the naming of surface colour codes and there has been no study of whether a person who passes the D15 can reliably name surface colours. Methods: One hundred and two people aged 11 to 65 years with abnormal colour vision were recruited from consecutively presenting optometric patients and were asked to name the colours of fabric, paint and cotton thread samples. There were 10 colours in each class of material and the samples were presented in a large (five to 10 degree angular subtense) and small size (2.5 deg and a single thread). The errors made were compared to those made by an age‐matched control group of equal size with normal colour vision. Results: The correlations between the Farnsworth D15 colour confusion index and colour naming errors were 0.62 for the large stimuli and 0.73 for the small stimuli. Its sensitivity and specificity identifymg those who made more errors than the worst performing colour normal person were 0.80 and 0.69 (large stimuli) and 0.75 and 0.71 (small stimuli). A Nagel anomaloscope range of less than 35 scale units provides essentially the same sensitivity and specificity. Conclusions: About 40 per cent of those with abnormal colour vision can name the main colours correctly under good visibility conditions. The D15 test is an imperfect predictor of those who can name surface colour codes correctly but it does provide useful information for general counselling. It is not suitable as a single test for occupational selection because it will pass 20 per cent who cannot name surface colours correctly and fail 30 per cent who can. In occupations in which recognition of surface colour codes is of critical importance, it may be best not to select people with abnormal colour vision because of the lack of a colour vision test that is a perfect predictor of the ability to recognise surface colours. 相似文献
32.
33.
A. A. Paul A. E. Black J. Evans T. J. Cole R. G. Whitehead 《Journal of human nutrition and dietetics》1988,1(6):437-450
Longitudinal measurements of breastmilk intake in 48 Cambridge infants showed that intake reached a peak of 824 g/24 h in boys and 741 g/24 h in girls in the third and fourth months, respectively. Regression analysis demonstrated that, in the early months, the infants' weight accounted for a major part of the variance in breastmilk intake. Infants in non-manual social classes received more breastmilk and started solids later than those in manual groups. In the early months weight gain showed a relative increase compared to growth standards, but later infancy was characterized by a progressive deceleration in weight and length gain. Adiposity, as measured by triceps skinfold thickness differed most markedly from growth charts and was only equivalent to the tenth standard centile at all ages. The lower skinfold thickness measurements are considered to be more appropriate to breastfed infants in general. 相似文献
34.
R Mokni A Chakar F Bleiberg-Daniel JL Mahu PA Walravens P Chappuis J Navarro D Lemonnier 《Acta paediatrica (Oslo, Norway : 1992)》1993,82(6-7):539-543
Biochemical markers of nutritional status (albumin, transthyretin, insulin-like growth factor-I and zinc) were measured in slowly growing two- to five-year-old, low-income Parisian children whose weight-for-height or height-for-age z scores (WHZ or HAZ) were between — 1 and — 2 SD of the NCHS median. The results were compared to controls who were matched for age, sex, and ethnic origin with WHZ and HAZ between — 1 and + 2 SD. Mean serum levels of transthyretin, albumin and insulin-like growth factor-I and mean plasma zinc concentrations were significantly lower in the growth-impaired children than in the controls ( p = 0.002, p = 0.006, p = 0.015, and p = 0.035, respectively). While the height-retarded children had low mean serum insulin-like growth factor-I values, the weight-retarded subjects had decreased levels of albumin, transthyretin and zinc when compared to controls. Lower mean levels of nutritional markers in healthy, slowly growing children suggest that inadequate dietary intakes of zinc, protein and/or energy may result in marginal delays in weight and height gains. 相似文献
35.
36.
Pied S; Voegtle D; Marussig M; Renia L; Miltgen F; Mazier D; Cazenave PA 《International immunology》1997,9(1):17-25
TCR V beta usage was examined in C57BL/6 mice infected with Plasmodium
yoelii. In addition to a polyclonal T cell activation, already described, a
superantigenic-like activity was observed during the acute infection. This
superantigenic activity induces a preferential deletion without prior
expansion of CD4+ and CD8+ T cells bearing the TCR V beta 9 segment. The
superantigen could be released by the parasite at different stages of its
development since the deletion of V beta 9+ T cells was observed in blood
and lymph nodes of mice infected either with sporozoites or with
erythrocytic stages. Injection of sporozoite or parasitized erythrocytes to
newborn mice led to a deletion and anergy of peripheral V beta 9+ T cells,
without affecting thymic T cell populations. These observations suggest
that the superantigen is released at very low concentrations during
parasite development. The role of such parasite superantigenic activity in
infectivity can be underlined by the observation that congenic BALB.D2
Mis1a mice lacking V beta 9 T cells are more susceptible to infection by P.
yoelii.
相似文献
37.
J W Cole D J Quint J E McGillicuddy K P Murphy 《AJNR. American journal of neuroradiology》1997,18(8):1420
We describe a technique for conducting a CT-guided biopsy of the brachial plexus region, report two illustrative cases, discuss potential complications, and conclude that, in selected cases, biopsy of lesions in the region of the brachial plexus can be performed safely with CT guidance. 相似文献
38.
Neonatal 6-hydroxydopa, but not DSP-4, elevates brainstem monoamines and impairs inhibitory avoidance learning in developing rats 总被引:1,自引:0,他引:1
C A Cornwell-Jones M W Decker J W Chang B Cole K M Goltz T Tran J L McGaugh 《Brain research》1989,493(2):258-268
The involvement of brain monoamines in learning and memory in developing rats was studied by comparing the effects of 3 different noradrenergic neurotoxin treatments. Two experimental groups of male Sprague-Dawley rat pups were injected systemically with 50 micrograms/g of N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) either on the day of birth or on postnatal days 17-18. Rats in the third experimental group were injected systemically with 60 micrograms/g of 6-hydroxydopa (6-OHDOPA) on postnatal days 0 and 2. Control littermates received vehicle. The animals were trained on an inhibitory avoidance task on postnatal days 27-29 and tested for retention 24 h later. The drug treatments produced comparable depletion of norepinephrine in the hippocampus and frontal cortex. 6-OHDOPA, but neither DSP-4 treatment, significantly elevated brainstem concentrations of norepinephrine and serotonin. In addition, 6-OHDOPA, but not DSP-4, significantly impaired retention of the inhibitory avoidance task. The impairment did not reflect insensitivity to the footshock used in training: both neonatal drug treatments tended to lower, not raise, footshock thresholds, as measured by a flinch test. High affinity choline uptake was not affected by either neonatal drug treatment in any of the brain areas examined. Thus, the 6-OHDOPA-induced behavioral deficit did not involve altered acetylcholine function. The results implicate brainstem monoamines in the modulation of learning and memory during development. 相似文献
39.
Paula Murphy Peterson Karen Kaufmann Rauen Jean Brown Jeane Cole 《Rehabilitation nursing》1994,19(4):229-238
Many concerns surround the preparation of a person with spina bifida for a successful transition into adult life and responsibilities. A model of intervention must be based on developmental concerns and timely issues from infancy through all stages of development to young-adult life. This article discusses, within a developmental framework, issues of transition in relation to physical, social, emotional, and educational/vocational needs; it also presents a conceptual framework for the transition into adulthood. Guidelines were developed by incorporating expected outcomes of people with spina bifida and using a philosophical framework that encompasses the achievement of a balance among dependence, independence, and interdependence. This model is based on developmental issues from infancy through all stages of development to young-adult life. Using this framework for care, the rehabilitation nurse can feel confident that the needs of clients with spina bifida and similar chronic conditions are being met. 相似文献
40.
Rapidly progressive parkinsonism in a self-reported user of ecstasy and other drugs. 总被引:2,自引:0,他引:2
A 38-year-old man developed parkinsonism that progressed to Hoehn and Yahr stage 5 within 4 years of onset. Response to ropinirole deteriorated, levodopa was not tolerated, and subthalamic nucleus stimulation has provided only partial relief of symptoms. He reported heavy use of Ecstasy through most of his twenties and thirties. His neurological problems may be unrelated to his drug use, but it is also possible they represent an idiosyncratic reaction. 相似文献