全文获取类型
收费全文 | 1682206篇 |
免费 | 112949篇 |
国内免费 | 3019篇 |
专业分类
耳鼻咽喉 | 22600篇 |
儿科学 | 52879篇 |
妇产科学 | 43904篇 |
基础医学 | 243163篇 |
口腔科学 | 45235篇 |
临床医学 | 145652篇 |
内科学 | 315616篇 |
皮肤病学 | 32405篇 |
神经病学 | 130823篇 |
特种医学 | 67313篇 |
外国民族医学 | 242篇 |
外科学 | 260957篇 |
综合类 | 40338篇 |
现状与发展 | 3篇 |
一般理论 | 408篇 |
预防医学 | 131575篇 |
眼科学 | 38287篇 |
药学 | 123342篇 |
3篇 | |
中国医学 | 4407篇 |
肿瘤学 | 99022篇 |
出版年
2018年 | 36588篇 |
2017年 | 28952篇 |
2016年 | 33416篇 |
2015年 | 15409篇 |
2014年 | 21047篇 |
2013年 | 31351篇 |
2012年 | 47756篇 |
2011年 | 64086篇 |
2010年 | 43869篇 |
2009年 | 35638篇 |
2008年 | 60947篇 |
2007年 | 67747篇 |
2006年 | 44659篇 |
2005年 | 45109篇 |
2004年 | 45857篇 |
2003年 | 45758篇 |
2002年 | 42161篇 |
2001年 | 68059篇 |
2000年 | 69708篇 |
1999年 | 57978篇 |
1998年 | 16579篇 |
1997年 | 14822篇 |
1996年 | 14776篇 |
1995年 | 14022篇 |
1994年 | 13292篇 |
1992年 | 47246篇 |
1991年 | 46645篇 |
1990年 | 45739篇 |
1989年 | 44634篇 |
1988年 | 41262篇 |
1987年 | 40264篇 |
1986年 | 38328篇 |
1985年 | 36754篇 |
1984年 | 27833篇 |
1983年 | 23740篇 |
1982年 | 14223篇 |
1981年 | 12865篇 |
1979年 | 27124篇 |
1978年 | 19439篇 |
1977年 | 16409篇 |
1976年 | 15411篇 |
1975年 | 16754篇 |
1974年 | 20379篇 |
1973年 | 19471篇 |
1972年 | 18443篇 |
1971年 | 17156篇 |
1970年 | 16461篇 |
1969年 | 15690篇 |
1968年 | 14248篇 |
1967年 | 12995篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
942.
Apramycin and gentamicin resistance in Escherichia coli and salmonellas isolated from farm animals 总被引:2,自引:0,他引:2
Since the aminoglycoside antibiotic apramycin was licensed for veterinary use in 1980, all isolates of Escherichia coli and salmonellas received at the Central Veterinary Laboratory have been monitored for resistance to apramycin and the related antibiotic gentamicin. During the period 1982-4, the incidence of resistance in E. coli to apramycin increased from 0.6% in 1982 to 2.6% in 1984. In salmonellas the incidence of resistance to apramycin increased from 0.1% in 1982 to 1.4% in 1984. Resistance to both apramycin and gentamicin was detected in six different salmonella serotypes, although an isolate of Salmonella thompson from poultry was resistant to gentamicin but not apramycin. Most of the cultures were isolated from pigs, although the incidence of apramycin resistance in S. typhimurium (DT 204C) from calves has shown a recent dramatic increase. All the isolates with one exception produced the enzyme aminoglycoside 3-N-acetyltransferase IV (ACC(3)IV). The resistance was transferable by conjugation in most of the strains examined, and the plasmids specifying the resistance have been found to belong to a number of different incompatibility groups. Plasmids from three E. coli strains were compatible with all the reference plasmids and belonged to a previously undescribed group which was investigated further. It is suggested that bacteria from humans should be examined for resistance to apramycin and gentamicin to determine the possibility of the antibiotic-resistance bacteria, and their genes, spreading from animals to humans. 相似文献
943.
944.
945.
946.
947.
P J Landrigan M G Cherniack F A Lewis L R Catlett R W Hornung 《Scandinavian journal of work, environment & health》1986,12(1):32-39
An industrial hygiene and medical survey was conducted in an iron foundry to study the occurrence of silicosis. Breathing zone exposures to respirable crystalline silica had been very high in 1977 [1 045 micrograms/m3 (geometric mean) for coremakers and 198 micrograms/m3 for fettlers]; exposures in 1980 and 1982 were substantially lower. A radiographic evaluation of 188 workers revealed silicosis in 18 (9.6%). Eight had category 1 profusion of small rounded pulmonary lesions (by the 1980 classification of the International Labour Office); two had category 2; and eight had category 3. Two had progressive massive fibrosis. Four workers without silicosis in 1977 had developed lesions by 1980. The prevalence increased from 1.5% among workers employed less than 20 years to 53% among longer term workers. No association was found between the prevalence of silicosis and cigarette smoking. Chronic cough was more common in workers with heavy current dust exposure than in those with light exposure, more common in smokers than in nonsmokers, and more common in silicotics than in nonsilicotics. A multiplicative interaction existed between dust exposure and smoking in the etiology of cough. Silicosis continues to exist in American foundries. Cigarette smoking does not contribute to the causation of silicosis, but it aggravates the attendant respiratory symptoms. 相似文献
948.
This paper critically examines the pharmacological provocation and treatment of panic disorder. An analysis of research findings on how panic attacks are induced indicates that there are psychological and non specific factors that may mediate biochemical etiological models, and these individual differences need to be investigated further. This has important implications for the psychopharmacological management of panic. A review of studies on treating panic disorder with imipramine and alprazolam emphasizes the importance of several non specific factors that include the role of self-directed in vivo exposure and changes in dysphoria and self-efficacy (subjective beliefs regarding personal competency) in predicting outcome. It is recommended that any treatment of panic-related disorders include self-directed, in vivo exposure. 相似文献
949.
In newly diagnosed adult patients with epilepsy followed prospectively on monotherapy, carbamazepine and phenytoin were associated with a fall in plasma uric acid, but sodium valproate and phenobarbitone were associated with a rise in plasma uric acid. The mechanisms and significance of these findings are discussed. 相似文献
950.
We report a case of mild visuo-spatial neglect consequent upon right-hemisphere stroke. At the time of testing, the patient had a complete left visual field deficit but only a very slight left hemiparesis. Under conventional testing conditions, line bisection performed with the right hand showed more severe left neglect than when performed with the left hand. This pattern of performance could, however, be modified, both quantitatively and qualitatively, by changing the starting position of the patient's hand when bisecting horizontal lines. The results suggest that spatio-motor cueing has a more profound effect upon task performance than does differential hemispheric activation per se. We also provide a demonstration that, in a normal subject, the starting position of the hand is likewise a crucial determinant of task performance. In this case, however, there is also an interaction between the hand (and hence hemisphere) deployed and the position of that hand in space. 相似文献