全文获取类型
收费全文 | 2389438篇 |
免费 | 190090篇 |
国内免费 | 9782篇 |
专业分类
耳鼻咽喉 | 30647篇 |
儿科学 | 78203篇 |
妇产科学 | 65453篇 |
基础医学 | 339516篇 |
口腔科学 | 65909篇 |
临床医学 | 225363篇 |
内科学 | 474344篇 |
皮肤病学 | 52821篇 |
神经病学 | 198522篇 |
特种医学 | 92312篇 |
外国民族医学 | 622篇 |
外科学 | 352305篇 |
综合类 | 55306篇 |
现状与发展 | 3篇 |
一般理论 | 838篇 |
预防医学 | 200614篇 |
眼科学 | 51839篇 |
药学 | 172172篇 |
11篇 | |
中国医学 | 4914篇 |
肿瘤学 | 127596篇 |
出版年
2018年 | 26432篇 |
2017年 | 20374篇 |
2016年 | 23273篇 |
2015年 | 26344篇 |
2014年 | 36569篇 |
2013年 | 55983篇 |
2012年 | 72212篇 |
2011年 | 77252篇 |
2010年 | 46553篇 |
2009年 | 44269篇 |
2008年 | 71234篇 |
2007年 | 75564篇 |
2006年 | 76846篇 |
2005年 | 74271篇 |
2004年 | 70801篇 |
2003年 | 68143篇 |
2002年 | 65353篇 |
2001年 | 109615篇 |
2000年 | 112703篇 |
1999年 | 94591篇 |
1998年 | 28205篇 |
1997年 | 25353篇 |
1996年 | 25949篇 |
1995年 | 25546篇 |
1994年 | 23928篇 |
1993年 | 22429篇 |
1992年 | 77376篇 |
1991年 | 75537篇 |
1990年 | 72898篇 |
1989年 | 69263篇 |
1988年 | 64376篇 |
1987年 | 63105篇 |
1986年 | 59937篇 |
1985年 | 57612篇 |
1984年 | 43899篇 |
1983年 | 37023篇 |
1982年 | 22912篇 |
1981年 | 20464篇 |
1980年 | 19159篇 |
1979年 | 39715篇 |
1978年 | 28768篇 |
1977年 | 23899篇 |
1976年 | 22737篇 |
1975年 | 23475篇 |
1974年 | 28125篇 |
1973年 | 27180篇 |
1972年 | 25118篇 |
1971年 | 23278篇 |
1970年 | 21394篇 |
1969年 | 19810篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
D Bild L S Geiss S M Teutsch B Gabella B A Hudspeth R M Schubert C W Gollmar D J Kaplan F A Connell J C Will 《Journal of clinical epidemiology》1988,41(10):999-1006
The pilot study for a sentinel health events surveillance system for deaths among persons under age 45 with diabetes was conducted in six states in 1984 and 1985. Two hundred and thirty-three events were identified. Information from death certificates, physicians, and families revealed that 22% died from acute complications of diabetes and 53% from chronic complications. Blood pressure measurement and urinalysis testing had been performed in the last year for almost all of the decedents, but other preventive practices were reported less frequently. Hypertension was present in 57% and of those, was not controlled in 73%. Forty-four percent were cigarette smokers at the time of death. Agreement between physicians and families was generally higher for clinical conditions than for care practices. This surveillance system appears to yield information about the health care of persons with diabetes not readily available from other sources, although modifications may be necessary before implementation. 相似文献
992.
M D Silverstein D A Albert N M Hadler M W Ropes 《Journal of clinical epidemiology》1988,41(7):623-633
993.
We examined six patients with Gardner's syndrome, eight first-degree relatives, and 31 age- and sex-matched controls to document the presence, distribution, and morphologic features of congenital hypertrophy of the retinal pigment epithelium. Patients with Gardner's syndrome had multiple, bilateral lesions, with 288 of 346 foci (83%) located posterior to the equator. Linear-shaped congenital hypertrophy of the retinal pigment epithelium, a distinctive finding in these patients, accounted for 44 of 140 large lesions (31%). Despite multifocal fundus involvement, results of electro-oculography were normal in all eyes tested. 相似文献
994.
Antisera have been made to synthetic peptides that correspond to eight different regions of the alpha A molecule. Together with a solid phase radioimmunoassay, these antisera have been used to quantitatively assess binding to enriched alpha crystallin preparations from six different cataractous and six different normal lenses. Seven of the eight antisera show no difference in binding to alpha crystallin from cataractous versus normal lenses, whereas the antiserum directed against the alpha A sequence 120-130 shows a statistically significant decrease in binding to the alpha crystallin from cataractous lenses. Together, these studies demonstrate the feasibility of using antipeptide sera as probes of polypeptide changes during cataractogenesis and suggest that the region of the alpha A crystallin molecule encompassing residues 120-300 may undergo covalent and/or noncovalent structural modification during the process of opacification in the human senile lens. 相似文献
995.
Vogt-Koyanagi-Harada syndrome and pregnancy 总被引:2,自引:0,他引:2
L P Steahly 《Annals of ophthalmology》1990,22(2):59-62
Two black women had bilateral anterior and posterior uveitis, nonrhegmatogenous retinal detachments, pleocytosis, headaches, dysacousis, and alopecia. These patients with Vogt-Koyanagi-Harada (VKH) syndrome improved clinically while they were pregnant after the discontinuation of corticosteroid treatment. They developed recurrent symptoms and findings after termination of their pregnancies. We speculate that changes in immunity and humoral constituents during pregnancy account for their remissions. It is important to assess the menstrual history and to avoid pregnancy before initiating steroid treatment for VKH syndrome. 相似文献
996.
A species-specific nucleotide sequence of Mycobacterium tuberculosis encodes a protein that exhibits hemolytic activity when expressed in Escherichia coli. 总被引:3,自引:2,他引:1
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Species-specific proteins may be implicated in the unique pathogenic mechanisms characteristic of Mycobacterium tuberculosis. In previous studies, a 3.0-kb species-specific DNA fragment of M. tuberculosis was identified (C. A. Parra, L. P. Londoño, P. del Portillo, and M. E. Patarroyo, Immun. 59:3411-3417, 1991). The nucleotide sequence of this 3.0-kb fragment has been obtained. This sequence was shown to contain two open reading frames (ORFs) whose putative gene products share 68.9% identity between each other. The major ORF shows 57.8% similarity with PLC-N and 53.2% similarity with PLC-H, two phospholipase C enzymes from Pseudomonas aeruginosa. The major ORF was amplified by PCR and cloned into the pGEX-5T expression vector. Cell extracts of Escherichia coli overexpressing this glutathione S-transferase fusion protein were shown to produce beta-hemolysis suggestive of phospholipase activity. Since phospholipase C enzymes have been reported as virulence factors of P. aeruginosa and also of the intracellular pathogen Listeria monocytogenes, it is possible that the proteins identified in this study could also play a role in sustaining tuberculosis infection in humans. 相似文献
997.
Multilocus DNA fingerprinting reveals high rate of heritable genetic mutation in herring gulls nesting in an industrialized urban site. 总被引:4,自引:0,他引:4
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
C L Yauk J S Quinn 《Proceedings of the National Academy of Sciences of the United States of America》1996,93(22):12137-12141
Genotoxins, such as polycyclic aromatic compounds, are ubiquitous in urban and industrial environments. Our understanding of the role that these chemicals play in generating DNA sequence mutations is predominantly derived from laboratory studies with specific genotoxins or extracts of contaminants from environmental media. Most assays are not indicative of the germinal effects of exposure in situ to complex mixtures of common environmental mutagens. Using multilocus DNA fingerprinting, we found the mutation rate in herring gulls inhabiting a heavily industrialized urban harbor (Hamilton Harbour, Ontario) to be more than twice as high as three rural sites: Kent Island, Bay of Fundy; Chantry Island, Lake Huron; and Presqu'ile Provincial Park in Lake Ontario. Overall we found a mutation rate of 0.017 +/- 0.004 per offspring band in Hamilton, 0.006 +/- 0.002 at Kent Island, 0.002 +/- 0.002 from Chantry Island, and 0.004 +/- 0.002 from Presqu'ile Provincial Park. The mutation rate from the rural sites (pooled) was significantly lower than the rate observed in Hamilton Harbour (Fisher's exact test, two-tailed; P = 0.0006). These minisatellite DNA mutations may be important biomarkers for heritable genetic changes resulting from in situ exposure to environmental genotoxins in a free-living vertebrate species. 相似文献
998.
J. L. BRENNAN 《Journal of paediatrics and child health》1993,29(S1):S37-S41
Abstract Resilient adolescents are notable for their social competence, which enables them to form and maintain close relationships. The evidence is that adolescents' social competence is derived from their experience of close relationships within their family. On the basis of structured interviews, adolescents' working models of attachments can be categorized into secure, dismissive, or pre-occupied. These attachment styles are associated with very divergent beliefs about the self and others, with differing patterns of emotion regulation and with differing risk profiles for maladjustment. Parenting styles and family relationships appear to have considerable influence on attachment behaviour. Further evidence for the importance of the family comes from research on ego development. Family level behavioural patterns have been discerned from family research interviews which are associated with stagnation or advancement in ego development during adolescence. Though the results suggest causal connections, the direction of effects is far from clear. Longitudinal research underpins the importance of childhood temperament as a contributing factor to the quality of the family environment that the child and then adolescent experiences. 相似文献
999.
New latex reagent using monoclonal antibodies to capsular polysaccharide for reliable identification of both oxacillin-susceptible and oxacillin-resistant Staphylococcus aureus. 总被引:5,自引:5,他引:0
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
J M Fournier A Bouvet D Mathieu F Nato A Boutonnier R Gerbal P Brunengo C Saulnier N Sagot B Slizewicz et al. 《Journal of clinical microbiology》1993,31(5):1342-1344
A new latex agglutination test (Pastorex Staph-Plus, Sanofi Diagnostics Pasteur), consisting of a mixture of latex particles coated with fibrinogen and immunoglobulin G for the detection of clumping factor and protein A and latex particles sensitized with monoclonal antibodies directed to Staphylococcus aureus serotype 5 and 8 capsular polysaccharides, was compared with three commercially available rapid agglutination methods for the identification of 220 isolates of S. aureus (61 oxacillin resistant) and 128 isolates of coagulase-negative staphylococci. The sensitivity for identification of S. aureus was high with the Pastorex Staph-Plus test (98.6%) compared with those of the other tests, which ranged from 91.8 to 84.5%. Test sensitivities for the identification of oxacillin-resistant S. aureus were as follows: Pastorex Staph-Plus, 95.1%; Pastorex Staph, 73.8%; Staphyslide, 72.1%; and StaphAurex, 49.2%. 相似文献
1000.