首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   298393篇
  免费   17420篇
  国内免费   421篇
耳鼻咽喉   4223篇
儿科学   10390篇
妇产科学   10342篇
基础医学   45376篇
口腔科学   7542篇
临床医学   24365篇
内科学   56257篇
皮肤病学   6425篇
神经病学   21150篇
特种医学   11645篇
外国民族医学   45篇
外科学   46993篇
综合类   7779篇
现状与发展   1篇
一般理论   160篇
预防医学   20063篇
眼科学   7001篇
药学   20975篇
中国医学   788篇
肿瘤学   14714篇
  2019年   2281篇
  2018年   3652篇
  2017年   2681篇
  2016年   3100篇
  2015年   3520篇
  2014年   4630篇
  2013年   7292篇
  2012年   9157篇
  2011年   9576篇
  2010年   6202篇
  2009年   5604篇
  2008年   8771篇
  2007年   9627篇
  2006年   9454篇
  2005年   9052篇
  2004年   8768篇
  2003年   8291篇
  2002年   7860篇
  2001年   13387篇
  2000年   13719篇
  1999年   11479篇
  1998年   3038篇
  1997年   2810篇
  1996年   2654篇
  1995年   2560篇
  1994年   2349篇
  1992年   8369篇
  1991年   8492篇
  1990年   8294篇
  1989年   8113篇
  1988年   7355篇
  1987年   7112篇
  1986年   6753篇
  1985年   6542篇
  1984年   4784篇
  1983年   4137篇
  1982年   2493篇
  1979年   4447篇
  1978年   3238篇
  1977年   2739篇
  1976年   2520篇
  1975年   2845篇
  1974年   3363篇
  1973年   3373篇
  1972年   3132篇
  1971年   2963篇
  1970年   2848篇
  1969年   2590篇
  1968年   2545篇
  1967年   2374篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Serum digoxin-like factor was detected in infants of diabetic mothers who were insulin-dependent or diet controlled. No statistical difference was found between the serum digoxin-like factor levels of the infants of diabetic mothers and the controls.  相似文献   
102.
In a single patient suffering from a major depressive episode with melancholia (DSM-III), both severe psychomotor symptoms, such as stupor and mutism, and mood disturbances could be abolished completely and promptly by administration of the benzodiazepine lorazepam. Remission of symptoms was entirely and immediately reversed by the benzodiazepine antagonist Ro 15-1788. These drug effects were constantly reproducible. Possible mechanisms of action and the influence of GABAergic neurotransmission on affective and psychomotor state are discussed.  相似文献   
103.
Apart from cannabis abuse in northern and southern Africa and khat chewing in north-eastern Africa, the history of drug abuse in Africa is relatively short. The abuse of drugs in Africa is nevertheless escalating rapidly from cannabis abuse to the more dangerous drugs and from limited groups of drug users to a wider range of people abusing drugs. The most common and available drug of abuse is still cannabis, which is known to be a contributing factor to the occurrence of a schizophrenic-like psychosis. The trafficking in and abuse of cocaine and heroin are the most recent developments in some African countries that had had no previous experience with these drugs. Efforts should be made to design and implement drug abuse assessment programmes to determine the real magnitude and characteristics of the problem and to monitor its trends. A lack of funds and a shortage of adequately trained personnel have made it difficult to implement drug abuse control programmes. In addition to formal drug control involving the implementation of legislation, there is an informal system of drug abuse control operating through the family, church, school, neighbourhood and work environment, as well as healthy recreational activities. It is suggested that efforts in African countries should be directed towards strengthening not only the formal drug control system but also informal control in order to compensate for the insufficient funds and the shortage of personnel trained in implementing formal drug control measures. It is very likely that the drug problems in African countries will worsen in future unless more effective measures are implemented to arrest the current situation.  相似文献   
104.
BACKGROUND: Allergen-specific immunotherapy is the only treatment for allergic disease providing long-lasting symptom relief. Currently, it is mainly based on the use of crude allergen extracts. The treatment may be improved by the use of genetically engineered allergens, hypoallergens, aiming at a more effective and safer therapy. OBJECTIVE: The aim of this study was to provide a rational design of hypoallergen candidates for immunotherapy by using structural information and knowledge of B and T cell epitopes of an allergen. METHODS: The three-dimensional structure of the major cat allergen Fel d 1 was systematically altered by duplication of selected T cell epitopes and disruption of disulphide bonds. Seven Fel d 1 derivatives were generated and screened for allergenic reactivity in comparison with recombinant Fel d 1 in competition-ELISA. The allergenicity was further evaluated in basophil activation experiments and T cell reactivity was assessed in a lymphoproliferation assay. RESULTS: Three out of seven Fel d 1 derivatives, with two duplicated T cell epitopes and one or two disulphide bonds disrupted, were carefully evaluated. The three derivatives displayed a strong reduction in allergenicity with 400-900 times lower IgE-binding capacity than recombinant Fel d 1. In addition, they induced a lower degree of basophil activation and similar or stronger T cell proliferation than recombinant Fel d 1. CONCLUSION: By a rational approach, we have constructed three Fel d 1 hypoallergens with reduced IgE-binding capacities and retained T cell reactivities. This strategy may be applied to any well-characterized allergen to improve immunotherapy for allergic patients.  相似文献   
105.
Intersexualität     
Zusammenfassung Intersexualität bezeichnet eine seltene Störung der somatosexuellen Differenzierung mit einer Inzidenz von etwa 2 pro 10.000 Geburten pro Jahr in Deutschland. Dahinter verbergen sich verschiedene Diagnosen einer vermehrten Virilisierung bei 46,XX-Karyotyp oder deutlich verminderter Virilisierung bei 46,XY-Karyotyp. Manchmal werden diese Störungen erst während der Pubertätsentwicklung entdeckt. Dann ist eine rasche Diagnostik zur Prognosestellung notwendig. Bei allen Jugendlichen mit Intersexualität muss das Management während der Pubertät viele Aspekte von der psychosexuellen Begleitung bis hin zur medizinischen Behandlung mit Hormonsubstitution oder Therapie und der Beratung hinsichtlich chirurgischer Maßnahmen enthalten.  相似文献   
106.
It is shown that with the holding potentials (Eh) ranging from -50 to -30 mV the amplitudes of the inward Ca current of identified neurons are significantly higher in old (20-24 months) Lymnaea stagnalis molluscs than in adult ones.  相似文献   
107.
108.
Two hundred and seventy-seven patients with advanced prostatic cancer were treated by either orchiectomy or oestrogen. During the 2-year follow-up period, the response to treatment was considered more favourable in the oestrogen group, and this response was particularly emphasised in patients with poorly differentiated tumour and metastases at the time of diagnosis. Further evaluations included the cardiovascular side effects of oestrogen therapy.  相似文献   
109.
110.
PURPOSE: Two experiments explored the extent to which induced blur, reduced luminance, and reduced visual fields affect drivers' steering performance in a driving simulator. METHODS: In experiment 1, ten young participants (M = 21.2 years) drove at approximately 89 km/h (55 mph) along a curvy roadway while being exposed to blur (0 to + 10 D), luminance (0.003 to 16.7 cd/m), and visual field (1.7 and 150 degrees) manipulations. In experiment 2, a new group of ten young participants (M = 18.5 years) drove while exposed to seven visual field sizes (1.7 to 150 degrees). RESULTS: Steering was sensitive to a reduced field size but not to the blur and luminance challenges. Acuity, on the other hand, was sensitive to the blur and luminance challenges but not to reduced field size. DISCUSSION: In healthy young drivers, steering performance is remarkably robust to severe blur and to extremely low luminances. These results support a key element of the selective degradation hypothesis advanced by Leibowitz and colleagues--that steering abilities are preserved at night even when the ability to recognize objects and hazards is not. Additional research should address the other element of this hypothesis--that drivers fail to appreciate the extent to which their visual abilities are degraded at night.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号