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   324217篇
  免费   16757篇
  国内免费   501篇
耳鼻咽喉   4649篇
儿科学   10776篇
妇产科学   10562篇
基础医学   48515篇
口腔科学   8149篇
临床医学   25991篇
内科学   62282篇
皮肤病学   6954篇
神经病学   22819篇
特种医学   12653篇
外国民族医学   43篇
外科学   50955篇
综合类   7906篇
现状与发展   1篇
一般理论   162篇
预防医学   20595篇
眼科学   7275篇
药学   22838篇
  11篇
中国医学   865篇
肿瘤学   17474篇
  2021年   2700篇
  2019年   2679篇
  2018年   4035篇
  2017年   2996篇
  2016年   3494篇
  2015年   3895篇
  2014年   5170篇
  2013年   7892篇
  2012年   10180篇
  2011年   10661篇
  2010年   6798篇
  2009年   6210篇
  2008年   9741篇
  2007年   10752篇
  2006年   10496篇
  2005年   10174篇
  2004年   9818篇
  2003年   9185篇
  2002年   8752篇
  2001年   14301篇
  2000年   14568篇
  1999年   12269篇
  1998年   3328篇
  1997年   2997篇
  1996年   2865篇
  1995年   2725篇
  1992年   8915篇
  1991年   8966篇
  1990年   8770篇
  1989年   8574篇
  1988年   7805篇
  1987年   7527篇
  1986年   7166篇
  1985年   6919篇
  1984年   5060篇
  1983年   4356篇
  1982年   2626篇
  1979年   4665篇
  1978年   3379篇
  1977年   2911篇
  1976年   2626篇
  1975年   2988篇
  1974年   3494篇
  1973年   3536篇
  1972年   3302篇
  1971年   3133篇
  1970年   3008篇
  1969年   2762篇
  1968年   2703篇
  1967年   2505篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
A microfluorometric method was used to determine the nuclear DNA content in the nasopharyngeal carcinomas (NPC) of 25 patients treated before 1983. Eleven patients are still alive with no evidence of disease (NED), while the rest died of their disease (DOD). All of the patients received a cycle of radiotherapy, while some also received chemotherapy or neck dissections. The neoplastic cells studied were taken from the original biopsy blocks, deparaffinized, isolated by enzymatic treatment and mechanical fragmentation, and then Feulgen-stained. The cytofluorometric measurement was carried out by a microphotometer equipped for fluorescence excitation and connected to a computer. This method allowed us to construct a histogram of the DNA content in the neoplastic cells. Different neoplastic classes were identified and represent the heteroclonality of the tumor, which can be expressed by the heteroclonality index (HCT). From the collected data it appears that the NED patients all had a low HTC (less than 1) and only 7 of the DOD patients had low HTCs (less than 1). Six of the DOD patients with a low HTC were in advanced stages of their tumor at the time of diagnosis, while the remaining patient did not complete his treatment. Our results show that the DNA analysis of the NPC cell population may offer a useful tool in predicting the biological behavior of this tumor and also improving its treatment.  相似文献   
92.
93.
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   
94.
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   
95.
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   
96.
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   
97.
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   
98.
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   
99.
100.
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   
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