全文获取类型
收费全文 | 2465319篇 |
免费 | 177534篇 |
国内免费 | 3693篇 |
专业分类
耳鼻咽喉 | 33786篇 |
儿科学 | 79660篇 |
妇产科学 | 65209篇 |
基础医学 | 363002篇 |
口腔科学 | 69679篇 |
临床医学 | 220039篇 |
内科学 | 481800篇 |
皮肤病学 | 54776篇 |
神经病学 | 194995篇 |
特种医学 | 91345篇 |
外国民族医学 | 508篇 |
外科学 | 368007篇 |
综合类 | 48550篇 |
现状与发展 | 12篇 |
一般理论 | 891篇 |
预防医学 | 195581篇 |
眼科学 | 56694篇 |
药学 | 181917篇 |
11篇 | |
中国医学 | 5061篇 |
肿瘤学 | 135023篇 |
出版年
2021年 | 21794篇 |
2019年 | 22048篇 |
2018年 | 30642篇 |
2017年 | 23012篇 |
2016年 | 25160篇 |
2015年 | 28524篇 |
2014年 | 40141篇 |
2013年 | 58928篇 |
2012年 | 82460篇 |
2011年 | 87677篇 |
2010年 | 51228篇 |
2009年 | 48151篇 |
2008年 | 80726篇 |
2007年 | 86055篇 |
2006年 | 86295篇 |
2005年 | 84031篇 |
2004年 | 80219篇 |
2003年 | 76928篇 |
2002年 | 73159篇 |
2001年 | 111081篇 |
2000年 | 113659篇 |
1999年 | 95549篇 |
1998年 | 27902篇 |
1997年 | 24425篇 |
1996年 | 24777篇 |
1995年 | 23379篇 |
1994年 | 21512篇 |
1993年 | 20327篇 |
1992年 | 73343篇 |
1991年 | 71423篇 |
1990年 | 69651篇 |
1989年 | 66903篇 |
1988年 | 61467篇 |
1987年 | 60200篇 |
1986年 | 56246篇 |
1985年 | 53987篇 |
1984年 | 40044篇 |
1983年 | 33994篇 |
1982年 | 20213篇 |
1979年 | 36417篇 |
1978年 | 25998篇 |
1977年 | 21513篇 |
1976年 | 20602篇 |
1975年 | 22159篇 |
1974年 | 26496篇 |
1973年 | 25153篇 |
1972年 | 23496篇 |
1971年 | 22308篇 |
1970年 | 20535篇 |
1969年 | 19583篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
C L Grady A M Grimes N Patronas T Sunderland N L Foster S I Rapoport 《Archives of neurology》1989,46(3):317-320
To determine if impaired dichotic performance in patients with dementia of the Alzheimer type is due to the inability to divide attention or the inability to perceive degraded auditory stimuli, we measured performance on tasks of both dichotic and degraded monotic speech materials. We also examined whether perception of degraded speech stimuli presented monaurally is related to abnormalities of temporal lobe anatomy and physiology, as we have shown for dichotic performance. Although the patients were impaired on both dichotic and monotic tests, significantly greater impairment was seen on the dichotic test. Our earlier finding of a significant relation between dichotic performance and measures of anterior temporal lobe atrophy and reduced glucose metabolism was replicated, but no significant relation was found between monotic tests and measures to temporal lobe integrity. We conclude that the inability to divide attention, rather than abnormal processing of degraded stimuli per se, is reflected in poor dichotic performance in patients with dementia of the Alzheimer type, and that dichotic performance, unlike degraded monotic perception, depends directly on the integrity of temporal cortex in these patients. 相似文献
992.
A Davis 《The Australian and New Zealand journal of psychiatry》1989,23(1):59-66
The Levine-Pilowsky depression questionnaire was used to compare the qualitative and quantitative characteristics of depression in 176 patients admitted to a general hospital following a suicide attempt and 65 psychiatric inpatients with a diagnosis of major affective disorder. The study showed that despite significant age and sex differences there was a striking similarity between the groups on all measures of depression. Diagnostic and therapeutic implications of these findings are discussed, and further research directions are suggested. 相似文献
993.
A Macpherson J Berth-Jones R A Graham-Brown 《Clinical and experimental dermatology》1989,14(4):304-305
We report a case of severe carcinoma-associated dermatomyositis which, having shown no response to conventional treatment, improved markedly within 48 h of plasmapheresis. We believe that this is the first time that dermatomyositis associated with an advanced carcinoma has been reported to respond in this way. Dermatomyositis can prove extremely difficult to treat and sometimes fails to respond even to very high doses of steroids and immunosuppressants. There is currently only a single report of the use of plasmapheresis in adult dermatomyositis. We therefore wish to support the findings of Dau and draw attention to the value of this therapeutic option in refractory dermatomyositis. 相似文献
994.
The results of clinical trials of ditrastic, an agent manufactured by Orion, Finland, are analyzed. The drug contains 1.5 or 3% of ditranol. Of the 59 patients treated with this drug complete resolution of clinical eruptions was achieved in 43, the condition of 10 patients considerably improved, a partial effect was observed in 4, and no effect in 2 patients. Therefore ditrastic has proved to be a highly effective agent for the treatment of psoriasis, convenient for outpatient therapy. 相似文献
995.
Occupational airborne allergic contact dermatitis from tylosin 总被引:2,自引:1,他引:1
996.
As the fields of astronomy, cosmology, and space travel move rapidly forward, so must space medicine. The manned space program and medical knowledge and support have developed in tandem. Dermatology will play a fundamental role in survival during space flight. This paper reviews past, present, and future accomplishments of the space program as they relate to medicine and characterizes some of dermatology's multiple roles in the future. It further explores the immunologic alterations noted during space flight and the attendant implications for health and well-being both in flight and on return to Earth, or to an Earthlike environment. 相似文献
997.
Iu A Syrovatka 《Problemy tuberkuleza》1989,(2):50-51
The effect of various concentrations of streptomycin, isoniazid, rifampicin and ethambutol on the function of the siliated epithelium of the frog oral mucosa was studied (110 experiments with 50 frogs). The level of inhibition of the siliated epithelium function depended on the properties of the drugs and their concentration in solution. More pronounced inhibition was induced by 15 per cent ethambutol solution and 10 per cent isoniazid solution. The least inhibition of the siliated epithelium function was observed with the use of 6.25 per cent streptomycin solution, 5 per cent isoniazid solution, 7.5 per cent ethambutol solution and 3.75 per cent rifampicin solution. 相似文献
998.
999.
The virD operon of Agrobacterium tumefaciens Ti plasmid encodes a DNA-relaxing enzyme. 总被引:15,自引:3,他引:12 下载免费PDF全文
J Ghai A Das 《Proceedings of the National Academy of Sciences of the United States of America》1989,86(9):3109-3113
The virD locus of Agrobacterium tumefaciens Ti plasmid encodes functions necessary for endonucleolytic cleavage of transferred DNA (T-DNA) prior to its transfer to plant cells. For the overproduction of the VIRD proteins in Escherichia coli a tac-virD operon fusion was constructed. A significant increase in the accumulation of VIRD proteins was observed in a lon protease-deficient E. coli host. The presence of an overlapping open reading frame (ORF) upstream of the VIRD1 coding sequence had a negative effect on VIRD1 production. A preparation containing VIRD proteins catalyzes the conversion of supercoiled (form I) DNA to relaxed (form IV) DNA. This activity is similar to that of a DNA topoisomerase. The relaxation activity lacks DNA sequence specificity, requires magnesium ion, and has no requirement for an energy source. Studies with plasmids that had lost defined DNA segments encompassing various virD coding regions showed that VIRD1 is the DNA-relaxing enzyme. In a density gradient centrifugation experiment, the DNA-relaxing activity sedimented as a 21-kDa polypeptide. Earlier studies of Jayaswal et al. [Jayaswal, R., Veluthambi, K., Gelvin, S. & Slightom, J. (1987) (J. Bacteriol. 169, 5035-5045] have shown that in E. coli VIRD2 alone is not sufficient for endonucleolytic cleavage of T-DNA and requires VIRD1 for its activity. 相似文献
1000.
Efficacy and toxicity of amiodarone for the treatment of supraventricular tachyarrhythmias 总被引:5,自引:0,他引:5
Amiodarone is an effective agent for all types of supraventricular tachyarrhythmias regardless of mechanism and may, in fact, control a high percentage of supraventricular tachyarrhythmias refractory to conventional antiarrhythmic agents. However, its toxicity should temper enthusiasm for the use of the medication in non-life-threatening arrhythmias. As always, when recommending specific therapies the potential benefit should be weighed in light of the related risk. In patients with life disordering, drug-refractory atrial fibrillation, it seems reasonable to attempt control with amiodarone. Likewise in patients with ectopic atrial tachycardias refractory to conventional agents, this seems reasonable as well. Other and better therapies are available for patients with life-threatening arrhythmias associated with the Wolff-Parkinson-White syndrome. While amiodarone is moderately effective in these patients, the advent of improved surgical techniques and the relatively low risk of an operation make surgery the treatment of choice. The role of IV amiodarone, acutely, in the treatment of supraventricular tachyarrhythmias remains to be defined. 相似文献