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   297251篇
  免费   17277篇
  国内免费   414篇
耳鼻咽喉   4207篇
儿科学   10304篇
妇产科学   10258篇
基础医学   45052篇
口腔科学   7514篇
临床医学   24197篇
内科学   56010篇
皮肤病学   6521篇
神经病学   21041篇
特种医学   11646篇
外国民族医学   43篇
外科学   46813篇
综合类   7769篇
现状与发展   1篇
一般理论   160篇
预防医学   19915篇
眼科学   7055篇
药学   20917篇
中国医学   787篇
肿瘤学   14732篇
  2019年   2265篇
  2018年   3639篇
  2017年   2665篇
  2016年   3101篇
  2015年   3516篇
  2014年   4615篇
  2013年   7243篇
  2012年   9107篇
  2011年   9491篇
  2010年   6151篇
  2009年   5562篇
  2008年   8723篇
  2007年   9561篇
  2006年   9423篇
  2005年   9010篇
  2004年   8707篇
  2003年   8208篇
  2002年   7802篇
  2001年   13355篇
  2000年   13678篇
  1999年   11446篇
  1998年   3037篇
  1997年   2798篇
  1996年   2645篇
  1995年   2556篇
  1994年   2351篇
  1992年   8339篇
  1991年   8466篇
  1990年   8285篇
  1989年   8094篇
  1988年   7328篇
  1987年   7086篇
  1986年   6735篇
  1985年   6529篇
  1984年   4772篇
  1983年   4125篇
  1982年   2476篇
  1979年   4431篇
  1978年   3236篇
  1977年   2739篇
  1976年   2504篇
  1975年   2833篇
  1974年   3357篇
  1973年   3365篇
  1972年   3122篇
  1971年   2949篇
  1970年   2843篇
  1969年   2584篇
  1968年   2540篇
  1967年   2376篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
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   
92.
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   
93.
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   
94.
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   
95.
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   
96.
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   
97.
98.
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   
99.
100.
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