全文获取类型
收费全文 | 1635篇 |
免费 | 176篇 |
国内免费 | 51篇 |
专业分类
耳鼻咽喉 | 19篇 |
儿科学 | 105篇 |
妇产科学 | 33篇 |
基础医学 | 165篇 |
口腔科学 | 57篇 |
临床医学 | 147篇 |
内科学 | 419篇 |
皮肤病学 | 30篇 |
神经病学 | 67篇 |
特种医学 | 231篇 |
外科学 | 126篇 |
综合类 | 111篇 |
预防医学 | 131篇 |
眼科学 | 15篇 |
药学 | 89篇 |
中国医学 | 4篇 |
肿瘤学 | 113篇 |
出版年
2023年 | 18篇 |
2022年 | 24篇 |
2021年 | 33篇 |
2020年 | 25篇 |
2019年 | 25篇 |
2018年 | 31篇 |
2017年 | 48篇 |
2016年 | 51篇 |
2015年 | 44篇 |
2014年 | 80篇 |
2013年 | 90篇 |
2012年 | 63篇 |
2011年 | 55篇 |
2010年 | 84篇 |
2009年 | 82篇 |
2008年 | 52篇 |
2007年 | 80篇 |
2006年 | 58篇 |
2005年 | 45篇 |
2004年 | 40篇 |
2003年 | 29篇 |
2002年 | 25篇 |
2001年 | 41篇 |
2000年 | 26篇 |
1999年 | 26篇 |
1998年 | 86篇 |
1997年 | 69篇 |
1996年 | 62篇 |
1995年 | 51篇 |
1994年 | 48篇 |
1993年 | 45篇 |
1992年 | 18篇 |
1991年 | 23篇 |
1990年 | 25篇 |
1989年 | 35篇 |
1988年 | 29篇 |
1987年 | 19篇 |
1986年 | 23篇 |
1985年 | 17篇 |
1984年 | 11篇 |
1983年 | 16篇 |
1982年 | 11篇 |
1981年 | 7篇 |
1980年 | 9篇 |
1979年 | 5篇 |
1978年 | 9篇 |
1977年 | 11篇 |
1976年 | 13篇 |
1975年 | 12篇 |
1972年 | 7篇 |
排序方式: 共有1862条查询结果,搜索用时 15 毫秒
11.
Isolation of a new clathrin heavy chain gene with muscle-specific expression from the region commonly deleted in velo-cardio-facial syndrome 总被引:3,自引:4,他引:3
Sirotkin H; Morrow B; DasGupta R; Goldberg R; Patanjali SR; Shi G; Cannizzaro L; Shprintzen R; Weissman SM; Kucherlapati R 《Human molecular genetics》1996,5(5):617-624
Velo-cardio-facial syndrome (VCFS) and DiGeorge syndrome (DGS) are
developmental disorders characterized by a spectrum of phenotypes including
velopharyngeal insufficiency, conotruncal heart defects and facial
dysmorphology among others. Eighty to eighty-five percent of VCFS/DGS
patients are hemizygous for a portion of chromosome 22. It is likely that
the genes encoded by this region play a role in the etiology of the
phenotypes associated with the disorders. Using a cDNA selection protocol,
we isolated a novel clathrin heavy chain cDNA (CLTD) from the VCFS/DGS
minimally deleted interval. The cDNA encodes a protein of 1638 amino acids.
CLTD shares significant homology, but is not identical to the ubiquitously
expressed clathrin heavy chain gene. The CLTD gene also shows a unique
pattern of expression, having its maximal level of expression in skeletal
muscle. Velopharyngeal insufficiency and muscle weakness are common
features of VCFS patients. Based on the location and expression pattern of
CLTD, we suggest hemizygosity at this locus may play a role in the etiology
of one of the VCFS-associated phenotypes.
相似文献
12.
Mahadevan MM; McIntosh Q; Miller MM; Breckinridge SM; Maris M; Moutos DM 《Human reproduction (Oxford, England)》1998,13(4):979-982
Cryopreservation of human zygotes and embryos has been routinely performed
by in-vitro fertilization clinics for many years. Karran and Legge (1996)
first reported that formaldehyde (FA) present in the cryoprotective
solutions can have a deleterious effect on mouse oocytes. FA is a
cytotoxic, carcinogenic and mutagenic chemical. The effect of FA on mouse
zygotes was investigated. In addition, the concentrations of FA in
propanediol (PROH) obtained from various sources were determined. Pooled
1-cell embryos were dispensed into droplets of modified Ham's F10 or human
tubal fluid containing various concentrations of FA. Since bovine serum
albumin (BSA) may minimize toxicity additional trials were done as above in
the absence of BSA. FA concentration in the standard 1.5 M PROH, from
different sources in water, was measured in the same assay using a standard
curve of 0-100 microM FA. FA in a complex medium had a significant
deleterious effect on embryo development and hatching but only at 1 mM
concentration (P < 0.000001; see Tables I-III). There was no significant
effect of FA at 100 microM. However, in a simple medium even 50 microM FA
decreased embryo hatching. FA was present in 1.5 M PROH from different
sources (range 1.0-35.3 microM concentration). It appears that FA
concentrations do not increase with storage because FA concentrations were
low even after opening and storage for 3 years on the shelf. This suggests
that FA is a contaminant during the manufacturing process and may vary from
manufacturer to manufacturer and batch to batch. Until further studies are
done to confirm the lack of toxicity to embryos during cryopreservation
(with or without FA scavengers) it may be prudent to screen all batches of
cryoprotectants for FA as part of quality control.
相似文献
13.
14.
SM Ismail 《Journal of clinical pathology》1993,46(11):1067-1068
15.
16.
17.
Formal retrospective case review and sudden infant death 总被引:2,自引:0,他引:2
A review of 24 consecutive sudden infant deaths was undertaken to evaluate the importance of the various stages in the postmortem assessment of such cases. Death in three cases was caused by obvious trauma. Of the remainder, 16 were attributed to sudden infant death syndrome (SIDS), 4 to accidental asphyxia (identified by death scene examination and/or formal case review) and 1 to a lingual thyroglossal duct cyst. Three (14%) of 21 deaths thought to be SIDS after postmortem examination were attributed to asphyxia following subsequent formal case review. 相似文献
18.
It is widely believed that the improved survival of young people with chronic diseases will be associated with the development of appropriate services within the adult healthcare domain. There is, however, little evidence to suggest that this is happening at a rate commensurate with clinical requirements. This paper highlights the multiplicity of barriers that impede the development of transition services to facilitate the transfer of medical care from the paediatric to the adult domain. Different models of transition care are described, and the terms 'transfer' and 'transition' are differentiated. The clinical demand for service development is highlighted, as well as the need for specific research in this area of healthcare delivery. 相似文献
19.
SK Roy AM Tomkins SM Akramuzzaman RH Behrens R Haider D Mahalanabis G Fuchs 《Archives of disease in childhood》1997,77(3):196-200
OBJECTIVE: To evaluate the impact of zinc supplementation on the clinical course, stool weight, duration of diarrhoea, changes in serum zinc, and body weight gain of children with acute diarrhoea. DESIGN: Randomised double blind controlled trial. Children were assigned to receive zinc (20 mg elemental zinc per day) containing multivitamins or control group (zinc-free multivitamins) daily in three divided doses for two weeks. SETTING: A diarrhoeal disease hospital in Dhaka, Bangladesh. PATIENTS: 111 children, 3 to 24 months old, below 76% median weight for age of the National Center for Health Statistics standard with acute diarrhoea. Children with severe infection and/or oedema were excluded. MAIN OUTCOME MEASURES: Total diarrhoeal stool output, duration of diarrhoea, rate of weight gain, and changes in serum zinc levels after supplementation. RESULTS: Stool output was 28% less and duration 14% shorter in the zinc supplemented group than placebo (p = 0.06). There were reductions in median total diarrhoeal stool output among zinc supplemented subjects who were shorter (less than 95% height for age), 239 v 326 g/kg (p < 0.04), and who had a lower initial serum zinc (< 14 mmol/l), 279 v 329 g/kg (p < 0.05); a shortening of mean time to recovery occurred (4.7 v 6.2 days, p < 0.04) in those with lower serum zinc. There was an increase in mean serum zinc in the zinc supplemented group (+2.4 v -0.3 mumol/l, p < 0.001) during two weeks of supplementation, and better mean weight gain (120 v 30 g, p < 0.03) at the time of discharge from hospital. CONCLUSIONS: Zinc supplementation is a simple, acceptable, and affordable strategy which should be considered in the management of acute diarrhoea and in prevention of growth faltering in children specially those who are malnourished. 相似文献
20.
WG Mitchell H Lynn JF Bale MA Maeder SM Donfield B Garg AH Tilton JK Willis TP Bohan 《Pediatrics》1997,100(5):817-824
BACKGROUND: Boys and young men with hemophilia treated with factor infusions before 1985 had a substantial risk of acquiring the human immunodeficiency virus (HIV) and the acquired immunodeficiency syndrome. This study was designed to assess the effects of HIV and hemophilia per se on neurological function in a large cohort of subjects with hemophilia, and to investigate the relationships between neurological disease and death during follow-up. METHODS: Three hundred thirty-three boys and young men (207 HIV seropositive and 126 HIV seronegative) were evaluated longitudinally in a multicenter, multidisciplinary study. Neurological history and examination were conducted at baseline and annually for 4 years. The relationship between neurological variables, HIV serostatus, CD4+ cell counts, and vital status at the conclusion of the study was examined using logistic regression models. RESULTS: The risks of nonhemophilia-associated muscle atrophy, behavior change, and gait disturbance increased with time in immune compromised HIV-seropositive subjects compared with HIV seronegative or immunologically stable HIV-seropositive subjects. The risk of behavior change in immune compromised HIV-seropositive hemophiliacs, for example, rose to 60% by year 4 versus 10% to 17% for the other study groups. Forty-five subjects (13.5%), all of whom were HIV seropositive, died by year 4. Subjects who died had had increased risks of hyperreflexia, nonhemophilia-associated muscle atrophy, and behavior change. CONCLUSIONS: These results indicate that immune compromised, HIV-seropositive hemophiliacs have high rates of neurological abnormalities over time and that neurological abnormalities were common among subjects who later died. By contrast, immunologically stable HIV-seropositive subjects did not differ from the HIV-seronegative participants. Hemophilia per se was associated with progressive abnormalities of gait, coordination, and motor function. 相似文献