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   149391篇
  免费   31147篇
  国内免费   2389篇
耳鼻咽喉   5166篇
儿科学   5343篇
妇产科学   2418篇
基础医学   2889篇
口腔科学   1490篇
临床医学   26516篇
内科学   46870篇
皮肤病学   7436篇
神经病学   14635篇
特种医学   6304篇
外科学   40785篇
综合类   229篇
现状与发展   72篇
一般理论   2篇
预防医学   6924篇
眼科学   3321篇
药学   858篇
中国医学   7篇
肿瘤学   11662篇
  2024年   685篇
  2023年   4779篇
  2022年   1174篇
  2021年   3049篇
  2020年   6007篇
  2019年   2128篇
  2018年   7341篇
  2017年   7306篇
  2016年   8376篇
  2015年   8360篇
  2014年   15428篇
  2013年   15539篇
  2012年   5348篇
  2011年   5358篇
  2010年   10281篇
  2009年   14173篇
  2008年   5697篇
  2007年   3901篇
  2006年   6370篇
  2005年   3673篇
  2004年   2957篇
  2003年   1916篇
  2002年   1999篇
  2001年   3786篇
  2000年   2993篇
  1999年   3194篇
  1998年   3630篇
  1997年   3449篇
  1996年   3353篇
  1995年   3200篇
  1994年   1935篇
  1993年   1557篇
  1992年   1366篇
  1991年   1399篇
  1990年   1051篇
  1989年   1171篇
  1988年   1009篇
  1987年   846篇
  1986年   884篇
  1985年   711篇
  1984年   543篇
  1983年   517篇
  1982年   511篇
  1981年   398篇
  1980年   358篇
  1979年   306篇
  1978年   331篇
  1977年   398篇
  1975年   277篇
  1972年   302篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
BACKGROUND: Endovascular radiofrequency obliteration has been used since 1998 as an alternative to conventional vein stripping surgery for elimination of saphenous vein insufficiency. OBJECTIVE: To demonstrate the long-term efficacy of this treatment modality. METHODS: Data were prospectively collected in a multicenter ongoing registry. Only great saphenous vein above-knee treatments were included in this study. Eight hundred ninety patients (1,078 limbs) were treated prior to November 2003 at 32 centers. Clinical and duplex ultrasound follow-up was performed at 1 week, 6 months, and 1, 2, 3, and 4 years. RESULTS: Among 1,078 limbs treated, 858 were available for follow-up within 1 week, 446 at 6 months, 384 at 1 year, 210 at 2 years, 114 at 3 years, and 98 at 4 years. The vein occlusion rates were 91.0%, 88.8%, 86.2%, 84.2%, and 88.8%, respectively; the reflux-free rates were 91.0%, 89.3%, 86.2%, 86.0%, and 85.7%, respectively; and the varicose vein recurrence rates were 7.2%, 13.5%, 17.1%, 14.0%, and 21.4%, respectively, at each follow-up time point at 6 months, and 1, 2, 3, and 4 years. Patient symptom improvement persisted over 4 years. CONCLUSIONS: Endovascular temperature-controlled radiofrequency obliteration of saphenous vein reflux exhibits an enduring treatment efficacy clinically, anatomically, and hemodynamically up to 4 years following treatment.  相似文献   
92.
93.
94.
Polycythemia vera is a myeloproliferative disease, which, if untreated, leads to thrombohemorrhagic complications and eventually to progressive myelofibrosis, anemia, and splenomegaly. Two newly available drugs, interferon alfa and imatinib mesylate, may alter the course of this disease. Used as single agents, each produces lasting remissions in about 75% of patients with polycythemia vera. Of significance, change in JAK2 expression has been reported after treatment with both agents.  相似文献   
95.
96.
97.
98.
The purpose of this study was to determine the genetic characteristics of foot polydactyly and identify its inheritance pattern by analyzing familial pedigree. Five cases from 2 Korean families were studied: 1 is a family whose members have been affected for 4 generations and the other for 2 generations. Using peripheral blood samples, we performed chromosomal analysis using the banding technique with Giemsa stain and karyotyping. We investigated the shape and structure of 46 chromosomes, looking for translation, deletion, inversion, ring chromosome, and isochromosome abnormalities. All peripheral blood samples demonstrated no chromosomal abnormalities, though the genetic nature of foot polydactyly and a new genetic locus was identified recently by other studies. Familial pedigree analysis suggested that polydactyly was inherited as an autosomal dominant trait in the first family. The mode of inheritance for the second family could not be determined due to an insufficient number of family members. The result of this study brought us to the conclusion that, while genetic factors play a major role in polydactyly, other factors may contribute to its occurrence.  相似文献   
99.
100.
Cerebrospinal fluid (CSF) from 7 patients with infantile spasms (mean age: 6.7 months) was collected before and after treatment with adrenocorticotropic hormone (ACTH). The concentration of neurotransmitter metabolites was analyzed using high-performance liquid chromatography and compared to the metabolite concentration in the CSF from 7 age-matched controls (mean age: 6.1 months). Pretreatment levels of CSF 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid, 3-methoxy-4-hydroxyphenyl glycol (MHPG), and kynurenine were significantly lower in infantile spasm patients compared to controls. Following treatment, marked increases in 5-HIAA and decreases in kynurenine levels were observed in the CSF of the 5 infants whose seizures were eliminated or reduced by ACTH. In the 2 nonresponders 5-HIAA levels decreased. The level of MHPG was reduced slightly in 5 infants, including the 2 nonresponders, and was increased in 2 responders. CSF homovanillic acid levels increased in 4 infantile spasm infants and decreased in 3 following ACTH. These data demonstrate that the presence of seizures in infantile spasms is associated with a significant decrease in serotonergic activity and that elimination of seizures by ACTH is accompanied by increased serotonin turnover. The simultaneous increase of 5-HIAA and decrease of kynurenine, an alternate metabolite of tryptophan, suggests an underlying disturbance of tryptophan metabolism in infantile spasms. The possibility that elimination of seizures by ACTH may be related to decreased production of certain kynurenine metabolites, particularly quinolinic acid, is discussed.  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