全文获取类型
收费全文 | 21956篇 |
免费 | 2451篇 |
国内免费 | 48篇 |
专业分类
耳鼻咽喉 | 160篇 |
儿科学 | 731篇 |
妇产科学 | 822篇 |
基础医学 | 3045篇 |
口腔科学 | 570篇 |
临床医学 | 2606篇 |
内科学 | 4845篇 |
皮肤病学 | 320篇 |
神经病学 | 1674篇 |
特种医学 | 879篇 |
外科学 | 2625篇 |
综合类 | 456篇 |
一般理论 | 35篇 |
预防医学 | 2294篇 |
眼科学 | 344篇 |
药学 | 1973篇 |
中国医学 | 11篇 |
肿瘤学 | 1065篇 |
出版年
2021年 | 289篇 |
2020年 | 188篇 |
2019年 | 330篇 |
2018年 | 365篇 |
2017年 | 285篇 |
2016年 | 297篇 |
2015年 | 332篇 |
2014年 | 480篇 |
2013年 | 642篇 |
2012年 | 948篇 |
2011年 | 979篇 |
2010年 | 518篇 |
2009年 | 496篇 |
2008年 | 844篇 |
2007年 | 1012篇 |
2006年 | 923篇 |
2005年 | 906篇 |
2004年 | 890篇 |
2003年 | 825篇 |
2002年 | 805篇 |
2001年 | 740篇 |
2000年 | 806篇 |
1999年 | 675篇 |
1998年 | 300篇 |
1997年 | 264篇 |
1996年 | 241篇 |
1995年 | 260篇 |
1994年 | 222篇 |
1993年 | 212篇 |
1992年 | 526篇 |
1991年 | 546篇 |
1990年 | 529篇 |
1989年 | 526篇 |
1988年 | 487篇 |
1987年 | 501篇 |
1986年 | 451篇 |
1985年 | 418篇 |
1984年 | 366篇 |
1983年 | 298篇 |
1982年 | 232篇 |
1981年 | 192篇 |
1980年 | 175篇 |
1979年 | 288篇 |
1978年 | 277篇 |
1977年 | 200篇 |
1976年 | 203篇 |
1975年 | 199篇 |
1974年 | 209篇 |
1973年 | 175篇 |
1972年 | 201篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
D C Roberts 《Pharmacology, biochemistry, and behavior》1989,32(1):43-47
It has been shown previously that 6-hydroxydopamine (6-OHDA)-induced lesions of the nucleus accumbens cause extinction of cocaine self-administration behavior, yet fail to affect the rate of apomorphine self-administration on a Fixed Ratio 1 schedule of reinforcement. Since the dopamine (DA) receptors in this nucleus should become supersensitive, and since these receptors are thought to mediate the reinforcing effects of apomorphine, then some change in apomorphine self-administration would be expected. We have therefore reinvestigated the effect of 6-OHDA lesions on apomorphine self-administration using a progressive ratio schedule of reinforcement. Rats were trained to self-administer apomorphine (0.033 mg/inj, IV) on a schedule in which the response requirements increased after each reinforcement. The breaking point was defined as the final ratio completed during each daily session. Sham lesions had no effect on the breaking points, and a steady increase in the breaking point was observed in the 6-OHDA-lesioned animals which may parallel the development of DA receptor supersensitivity. 相似文献
72.
73.
Elizabeth Roberts Steven D Void Robert H Rosa David C Dries 《Ophthalmic surgery, lasers & imaging》2007,38(4):326-327
The presence of collateral vessels in a young child with glaucoma is rare. The authors describe a case of collateral vessel regression with intraocular pressure reduction in a child with primary congenital glaucoma. Six months following 180 degrees goniotomies in each eye, the intraocular pressure was reduced, dilation of the retinal arteries and veins resolved, and collateral vessels in both eyes regressed. Intraocular pressure reduction may lead to the regression of collateral vessels in children with primary congenital glaucoma. 相似文献
74.
Early life precursors of psychiatric outcomes in adulthood in subjects at risk for schizophrenia or affective disorders. 总被引:2,自引:0,他引:2
L Erlenmeyer-Kimling D Rock E Squires-Wheeler S Roberts J Yang 《Psychiatry research》1991,39(3):239-256
In the New York High-Risk Project (NYHRP), 186 offspring of schizophrenic, affectively ill, and psychiatrically normal parents have been followed prospectively from 1971-72 to the average age of 27 years in 1990 with the goal of identifying early precursors of later psychopathology. In this report, we use path analyses to examine the relationship of several life-history variables to three pathological outcomes in the offspring: namely, psychosis, psychiatric hospitalization, and psychological dysfunction. The chief direct relationship with these outcomes is the effect of having a schizophrenic parent. The latter effect is also mediated indirectly by IQ. 相似文献
75.
76.
F. Okada T. J. Crow G. W. Roberts 《Journal of neural transmission (Vienna, Austria : 1996)》1991,84(1-2):147-153
Summary We have measured the amount of Gi (the inhibitory G-protein) or Go (a similar G-protein of unknown function) in 5 areas of the medial temporal lobe of control and schizophrenic brains utilizing pertussis toxin-catalyzed ADP ribosylation. The material used has previously been shown to have asymmetrical structural abnormalities of the ventricular system. The amount of Gi or Go was reduced on the left side in the hippocampus, amygdala and parahippocampal gyrus, the difference reaching significance in the hippocampus. This data is the first report of a neurochemical correlate of the structural change in the brains of patients with schizophrenia. Decreased Gi or Go in hippocampus may relate to other reported neurochemical deficits or other transmembrane signalling abnormalities. Further investigations of these indices of secondary messenger function in relation to structural changes are indicated. 相似文献
77.
C D Holman P Psaila-Savona M Roberts J C McNulty 《British journal of industrial medicine》1987,44(12):810-818
The relation of chronic bronchitis and respiratory dysfunction to age, tobacco smoking, and occupational exposure to surface and underground mining operations were examined in a cross sectional survey of 1363 men employed in the Kalgoorlie mining industry in 1985. Overall, the prevalence of chronic bronchitis was 14%. Eleven per cent of the workers had obstructive lung disorder (FEV1/FVC less than 0.70) and 9% had restrictive lung disorder (FVC less than 0.80 of predicted for height and age). There was little change in the prevalence of chronic bronchitis from that observed in a survey of the same industry in 1961-2. Only 1% of the workers in 1985 had radiographic signs of silicosis compared with 22% in 1961-2. Age, smoking, and underground mining experience all exerted strong effects on the development of chronic bronchitis with or without associated respiratory function abnormalities. After control of confounding by age and smoking, it was estimated that compared with a lifetime non-miner, the odds ratio (OR) of chronic bronchitis was 1.8 (95% confidence interval, 1.0-3.3) for one to nine years underground mining gold, 2.5 (1.2-5.2) for 10-19 years, and 5.1 (2.4-10.9) for 20 or more years. Underground mining of minerals other than gold was also associated with chronic bronchitis (OR = 5.1; 95% CI, 1.1-25.0) whereas exclusive surface mining had only a small empirical effect (OR = 1.3; 95% CI, 0.6-2.5). It is estimated that the proportion of cases of chronic bronchitis in working underground miners due to occupational factors is 50%. The results support the existence of an industrial cause of chronic bronchitis, although caution must be exercised in generalising the results to miners with progressive and sever respiratory impairment. 相似文献
78.
79.
P-fimbriae vaccines 总被引:3,自引:0,他引:3
M. Bernice Kaack Auli Pere Timo K. Korhonen Stefan B. Svenson James A. Roberts 《Pediatric nephrology (Berlin, Germany)》1989,3(4):386-390
To test for cross-protective capacity of two different P-fimbriae vaccines we vaccinated baboons with fimbriae purified from either Escherichia coli strain ER2 or strain JR1. The vaccinated animals showed elevated antibody titers to P-fimbriae from each of the E. coli strains used, suggesting cross-reactivity as was expected from the results of immunoprecipitation of the fimbriae. Enzyme-linked immunosorbent assay inhibition by heterologous P-fimbriae proved this to be true immunologic cross-reactivity. 相似文献
80.
Antihistamines and driving ability: evidence from on-the-road driving studies during normal traffic.
David J Roberts 《Annals of allergy, asthma & immunology》2005,94(3):407-9; author reply 409-10