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   75519篇
  免费   5245篇
  国内免费   2603篇
耳鼻咽喉   567篇
儿科学   1699篇
妇产科学   907篇
基础医学   11769篇
口腔科学   1013篇
临床医学   5699篇
内科学   11906篇
皮肤病学   1329篇
神经病学   6312篇
特种医学   1084篇
外国民族医学   11篇
外科学   5459篇
综合类   8095篇
现状与发展   10篇
一般理论   1篇
预防医学   6455篇
眼科学   1120篇
药学   12215篇
  9篇
中国医学   3472篇
肿瘤学   4235篇
  2023年   1018篇
  2022年   1830篇
  2021年   2362篇
  2020年   2140篇
  2019年   2736篇
  2018年   2709篇
  2017年   2337篇
  2016年   2309篇
  2015年   2522篇
  2014年   4169篇
  2013年   5100篇
  2012年   4186篇
  2011年   4967篇
  2010年   4188篇
  2009年   3605篇
  2008年   3541篇
  2007年   3276篇
  2006年   2867篇
  2005年   2487篇
  2004年   2181篇
  2003年   1926篇
  2002年   1620篇
  2001年   1413篇
  2000年   1096篇
  1999年   1097篇
  1998年   916篇
  1997年   861篇
  1996年   721篇
  1995年   686篇
  1994年   617篇
  1993年   559篇
  1992年   488篇
  1991年   469篇
  1990年   435篇
  1989年   371篇
  1988年   348篇
  1987年   273篇
  1986年   256篇
  1985年   934篇
  1984年   1136篇
  1983年   881篇
  1982年   1007篇
  1981年   947篇
  1980年   705篇
  1979年   671篇
  1978年   481篇
  1977年   403篇
  1976年   437篇
  1975年   337篇
  1973年   228篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
冠心病行为模式与心理状态的相关性探讨   总被引:8,自引:1,他引:7  
目的为探讨A型行为在冠心病(CoronaryHeartDisease,CHD)中的作用及与心理状态的相关性。方法对114例CHD及37例非CHD应用心理测验方法对照调查。结果发现A型行为的人易患CHD。CHDA型行为者在焦虑、抑郁、人际关系、认识、敌对性症状因子分较CHD非A型行为者有明显增高。CHD非A型行为者也具有一些特有的心理症状。结论CHD病人的行为模式与病后的某些心理表现呈正相关。  相似文献   
72.
Reports of the human teratogenicity of retinoids have raised concern about the potential human teratogenicity of high doses of vitamin A. Nevertheless, there are few human case reports of excess intake of vitamin A during pregnancy and defective outcomes. No epidemiological studies have been carried out on this subject. Here we present the results of an epidemiological study of prenatal exposure to high doses of vitamin A in Spain, using data from the Spanish hospital-based, case-control registry. Although it is difficult to reach conclusions with such a very low exposure level (1.3 per 1,000 livebirths), our results suggest that a teratogenic effect might exist for exposures to high doses of vitamin A (OR = 0.5, p = 0.15 for less than 40,000 FU and OR = 2.7, p = 0.06 for 40,000 1U or more). As we might expect, this effect also seems to be related to the organogenetic status (OR = 5.4, p = 0.1 for 1st –2nd month, OR = 1.8, p = 0.4 for 3rd onwards) at the time of exposure.  相似文献   
73.
Large granular lymphocytic (LGL) leukaemia and chronic natural killer cell lymphocytosis (CNKL) are chronic indolent disorders often associated with neutropenia and constitutional symptoms. Severe anaemia occurs in about 20% of patients and is currently treated with corticosteroids followed by oral cyclophosphamide in non-responders. 30% of patients fail initial measures, and salvage therapy is inadequate. We describe three transfusion-dependent patients (two with T-LGL leukaemia, one with CNKL) refractory to corticosteroids, cyclophosphamide, and in one case fludarabine. Cyclosporine A (CSA) initiation resulted in prompt transfusion-independence and was well tolerated in all patients, making it an attractive alternative therapy for this disorder.  相似文献   
74.
韩培  白步云 《中国肿瘤临床》1993,20(10):759-761
本文报告260例恶性肿瘤患者血清维生素A、E、C水平的测定结果。发现除慢性白血病外,蓁7种恶性肿瘤患者血清维生素A水平平均显著低于健康人(P<0.01);急性白血,肝癌、食管癌患者血清维生素E水平显著低于健康人(P<0.05);急性粒细胞白血病、急性单核细胞白血病、肝癌患者血维生素C水平显著低于健康人(P<0.01)。本研究工作为维生素A、E、C药物在肿瘤临床上的应用提供了参考。  相似文献   
75.
76.
Botulinum A toxin (BOTOX®) was injected into the gastrocnemius muscle of 26 cerebral palsy subjects with equinus gait. All subjects were equinus walkers without fixed contracture of the triceps-surae muscle. Injections were performed at 3 month intervals, if needed, as determined by the treating clinician. There were 14 subjects with spastic hemiplegia, 11 subjects with spastic diplegia and 1 subject with spastic quadriplegia. In the case of those subjects with bilateral equinus gait the dose was divided and given into both the right and left gastrocnemius muscle. Gait analysis data was collected prior to the first injection and subsequently at 3 month intervals for 1 year. Kinematic and electromyographic data was obtained. This data was analyzed to provide objective information about the outcome of treatment. Four subjects moved away and were lost to follow-up. Seven subjects left the study to have surgery. The data collected revealed statistically significant improvements in dynamic ankle dorsiflexion in both stance and swing phases, stride length, and electromyography of the tibialis anterior. There were no complications. While the results of this study are promising, additional prospective studies are needed to determine the feasibility of preventing muscle contractures over a longer time period. Furthermore, there is a need for inclusion of other muscles in future research. Future research should also compare BOTOX® treatment with alternative methods of dealing with muscle spasticity such as: casting, orthotic devices, physical therapy, selective dorsal rhizotomy, and surgical lengthening.  相似文献   
77.
1 Heterocyclic amines are formed in parts per billion levels when meat is cooked.
2 The heterocyclic amines MeIQx and PhIP are efficiently absorbed into the systemic circulation after ingestion of cooked food.
3 We have shown that MeIQx and PhIP, both in vitro and in vivo , are substrates for human hepatic CYP1A2, which exclusively and efficiently catalyses their conversion to genotoxic hydroxylamines.
4 MeIQx and PhIP are promutagens. MeIQx is a very powerful bacterial mutagen whereas PhIP is a more potent mammalian cell mutagen. Using a mammalian cell target gene, hprt , we have shown that PhIP induces a characteristic mutational 'fingerprint'.
5 MeIQx and PhIP are carcinogenic in bioassays. The PhIP mutational 'fingerprint' has been detected in the Apc gene of 5/8 colonic tumours induced by PhIP in rats.  相似文献   
78.
A seroepidemiological study was carried out in a geographically well-defined area in rural Crete in order to determine the prevalence of A, B and C hepatitis markers in the local population. Serum samples were obtained from 257 subjects (94 males, 163 females), aged 15 years and over, who visited the primary health care services of the Spili Health Centre between July 1993 and March 1994, and from 164 subjects (83 males, 81 females) randomly selected from households in three neighbouring villages of the study area. In samples obtained from the Spili Health Centre, antibodies to hepatitis A virus (anti-HAV) were detected in 234/244 (95.9%) subjects, antibodies to hepatitis B virus core antigen (HBcAb) were detected in 63/257 (24.5%) subjects and antibodies to hepatitis C virus (anti-HCV) were detected in 28/257 (10.9%) subjects. The corresponding figures for those randomly selected from the villages were 135/154 (87.7%), 16/164 (9.8%) and 5/164 (3%) respectively. Hepatitis B surface antigen (HBsAg) was positive in three (1.2%) subjects from the first group, while none of those recruited from the villages were positive for HBsAg. Interestingly, hepatitis markers were closely associated with age. No subjects under the age of 15 years showed evidence of prior hepatitis A infection and approximately 20% of those between 15 and 44 years of age were also negative. By contrast, practically all subjects older than 44 years were anti-HAV positive. Similarly, the majority of all those who were anti-HCV positive were older subjects. Seroepidemiology of hepatitis in this well-defined population seems to be different from other parts of Greece, at least for hepatitis B and C viruses. There is a very low prevalence of HBsAg and a very high incidence of anti-HCV. Low exposure to HAV, as found in other parts of the country, was also found in the younger generation in this rural area of Crete.  相似文献   
79.
Alcohol and Platelet Function   总被引:3,自引:0,他引:3  
Epidemiological studies have shown that moderate consumption of alcoholic beverages is inversely related to the incidence of the complications of coronary artery disease. The protective effect of ethanol may be partially attributable to an inhibitory effect of ethanol on platelets. This article summarizes the experimental observations that ethanol inhibits platelet responses to specific physiological agonists. In alcoholics, various platelet defects have been observed, but these may be influenced by metabolic factors rather than the presence of ethanol alone. The acute effects of ethanol on platelet functions both in vivo and ex vivo will be reviewed. Evidence will be presented demonstrating that ethanol added acutely in vitro inhibits phospholipase A2 in stimulated platelets. The interaction of ethanol with other signal transduction pathways will also be discussed.  相似文献   
80.
本文采用俯卧拍背法缓解胆绞痛41例,其中23例经此法治疗后疼痛立即消失(56.1%);15例明显缓解(36.6%);3例缓解不明显(7.3%)。具有操作简便、安全,易被患者接受,值得推广。  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