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   80057篇
  免费   7790篇
  国内免费   5540篇
耳鼻咽喉   701篇
儿科学   940篇
妇产科学   845篇
基础医学   8154篇
口腔科学   1296篇
临床医学   10612篇
内科学   10655篇
皮肤病学   799篇
神经病学   3351篇
特种医学   2563篇
外国民族医学   31篇
外科学   7252篇
综合类   16583篇
现状与发展   29篇
一般理论   5篇
预防医学   6835篇
眼科学   1928篇
药学   8911篇
  108篇
中国医学   5592篇
肿瘤学   6197篇
  2025年   21篇
  2024年   1083篇
  2023年   1512篇
  2022年   3112篇
  2021年   3936篇
  2020年   3254篇
  2019年   2662篇
  2018年   2540篇
  2017年   2637篇
  2016年   2291篇
  2015年   3553篇
  2014年   4493篇
  2013年   4411篇
  2012年   6275篇
  2011年   6572篇
  2010年   4769篇
  2009年   4007篇
  2008年   4584篇
  2007年   4620篇
  2006年   4215篇
  2005年   3787篇
  2004年   3006篇
  2003年   3142篇
  2002年   2651篇
  2001年   2179篇
  2000年   1635篇
  1999年   1399篇
  1998年   794篇
  1997年   789篇
  1996年   550篇
  1995年   504篇
  1994年   474篇
  1993年   290篇
  1992年   292篇
  1991年   299篇
  1990年   235篇
  1989年   190篇
  1988年   139篇
  1987年   116篇
  1986年   102篇
  1985年   74篇
  1984年   35篇
  1983年   38篇
  1982年   19篇
  1981年   23篇
  1980年   8篇
  1979年   16篇
  1977年   10篇
  1974年   7篇
  1973年   8篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
91.
BACKGROUND: Hereditary angioedema (HAE) is a rare disorder characterized by recurrent attacks of localized subcutaneous or submucosal edema. It is inherited in an autosomal dominant fashion and caused by a deficiency of C1 inhibitor (C1 INH). Most patients with HAE have an absolute deficiency of C1 INH (type I HAE), whereas the rest (approximately 15%) synthesize a dysfunctional C1 INH protein (type II HAE). Mosaicism is rare in HAE. OBJECTIVE: To describe the clinical manifestations, laboratory findings, and molecular genetic studies in a Taiwanese family with type I HAE with paternal mosaicism. METHODS: A family that included a 34-year-old man (index patient) and his 25-year-old brother who both had recurrent peripheral angioedema was evaluated. A younger sister had died of an unexplained cause at 18 years of age. We analyzed blood levels of C3, C4, and C1 INH and sequenced the SERPING] (C1NH) gene that codes for C1 INH in 5 family members, including the parents and 3 brothers. RESULTS: The 4 men in the family had a novel mutation c.3_73del, p.N1fsX34 in exon 3 of the C1INH gene, resulting in C1 INH deficiency. Although the father carried this mutant gene, he had normal serum levels of C1 INH. Based on quantitative analysis of allele dosage by DNA fragment analysis (GeneScan), the father was determined to have genetic mosaicism. CONCLUSION: Parental mosaicism is a possible explanation for normal C1 INH plasma concentrations in both parents despite clinically apparent HAE in the children.  相似文献   
92.
93.
94.
B H Wen  S R Yu  G Q Yu  Q J Li  X Zhang 《Acta virologica》1991,35(6):538-544
Four Coxiella burnetii isolates in China and two reference strains were compared by SDS-PAGE and immunoblotting. The SDS-PAGE profiles of whole cells and LPS of Chinese isolates Qiyi, Xinqiao, and YS-8 were found closely related to Henzerling strain, and different from the Grita strain. In immunoblot assay of LPS and proteinase K-digested whole rickettsiae minor differences were seen in polysaccharide structure among the Chinese isolates by phase I monoclonal antibody. The present results suggest that the strains reported here may be divided into three groups according to the polysaccharide structure: Xinqiao and Henzerling strains (1), YS-8 and Grita (2), and Qiyi (3).  相似文献   
95.
采用HRP追踪法,对成年大鼠膈神经运动纤维的起源和初级传入神经元胞体的位置及在其中枢突脊髓的投射进行了观察。结果表明,膈神经运动纤维在脊髓标记(膈核)主要分布在注射侧C_3-C_5脊髓节段的前角。隔神经感觉纤维初级传入标记的神经元见于注射侧C_3-C_6后根节,其中C_4标记的细胞数最多。  相似文献   
96.
Qin QH  Swain MV 《Biomaterials》2004,25(20):5081-5090
Application of a micro-mechanics cell model to dentin composites for determination of their effective mechanical properties is discussed in this paper. The dilute micro-mechanics model for fibre-reinforced composites is utilized and the corresponding cell model is chosen to consist of a circular hollow cylinder filled with liquid or gas phase, which is surrounded by two circular cylindrical shells, a thin shell and a matrix phase. Each layer of cylindrical shell is here considered as a composite consisting of collagen fibrils, with mineralized hydroxyapatite, loosely connected to their neighbours, and water (or gas in the case of dry dentin composite). Determination of the effective material properties of such a three phase composite is discussed. Using the cell model the effect of porosity, thickness of each cylindrical shell, and mineral content on material properties is analysed. Results obtained from nano-indentation observations are compared with numerical predictions of the analytical model.  相似文献   
97.
Individuals living in regions where malaria is endemic develop an acquired immunity to malaria which enables them to remain asymptomatic while still carrying parasites. Field studies indicate that cumulative exposure to a variety of diverse Plasmodium parasites is required for the transition from symptomatic to asymptomatic malaria. This study used a simulation model of the within-host dynamics of P. falciparum to investigate the development of acquired clinical immunity under different transmission conditions and levels of parasite diversity. Antibodies developed to P. falciparum erythrocyte membrane protein 1 (PfEMP1), a clonally variant molecule, were assumed to be a key human immunological response to P. falciparum infection, along with responses to clonally conserved but polymorphic antigens. The time to the development of clinical immunity was found to be proportional to parasite diversity and inversely proportional to transmission intensity. The effect of early termination of symptomatic infections by chemotherapy was investigated and found not to inhibit the host's ability to develop acquired immunity. However, the time required to achieve this state was approximately double that compared to when no treatment was administered. This study demonstrates that an immune response primarily targeted against PfEMP1 has the ability to reduce clinical symptoms of infections irrespective of whether treatment is administered, supporting its role in the development of acquired clinical immunity. The results also illustrate a novel use for simulation models of P. falciparum infections, investigation of the influence of intervention strategies on the development of naturally acquired clinical immunity.  相似文献   
98.
我国正常生育力男子精浆的微量元素研究   总被引:12,自引:5,他引:7  
本文报告测试了68例正常生育力成年男子精浆中的锌、铜,铁等微量元素和镁,测试结果如下:锌130±5.64μg/ml,铜1.84±0.158μg/ml,铁0.801±0.104μg/ml,镁103.86±10.01μg/ml。所测得的数值均在正常范围内。在正常范围内的精液,精浆中的锌、镁含量与精液质量(精子密度和活动力)之间无显著差异。但铜的含量与精子活动度关系密切,含量高则活动度差,反之则活动度好。铁的含量与精子密度关系也十分密切,含量高时精子密度也高。  相似文献   
99.
Diabetes is the seventh leading cause of death in United States. Dietary intake and behaviors are essential components of diabetes management. Growing evidence suggests dietary components beyond carbohydrates may critically impact glycemic control. Assessment tools on mobile platforms have the ability to capture multiple aspects of dietary behavior in real-time throughout the day to inform and improve diabetes management and insulin dosing. The objective of this narrative review was to summarize evidence related to dietary behaviors and composition to inform a mobile image-based dietary assessment tool for managing glycemic control of both diabetes types (type 1 and type 2 diabetes). This review investigated the following topics amongst those with diabetes: (1) the role of time of eating occasion on indicators of glycemic control; and (2) the role of macronutrient composition of meals on indicators of glycemic control. A search for articles published after 2000 was completed in PubMed with the following sets of keywords “diabetes/diabetes management/diabetes prevention/diabetes risk”, “dietary behavior/eating patterns/temporal/meal timing/meal frequency”, and “macronutrient composition/glycemic index”. Results showed eating behaviors and meal macronutrient composition may affect glycemic control. Specifically, breakfast skipping, late eating and frequent meal consumption might be associated with poor glycemic control while macronutrient composition and order of the meal could also affect glycemic control. These factors should be considered in designing a dietary assessment tool, which may optimize diabetes management to reduce the burden of this disease.  相似文献   
100.
The European Journal of Health Economics - The relationship between outpatient and inpatient care is central to the current healthcare reform debate especially in developing countries. Despite the...  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