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   23996篇
  免费   2051篇
  国内免费   46篇
耳鼻咽喉   293篇
儿科学   738篇
妇产科学   621篇
基础医学   3393篇
口腔科学   339篇
临床医学   2744篇
内科学   4784篇
皮肤病学   368篇
神经病学   2514篇
特种医学   536篇
外科学   2706篇
综合类   282篇
一般理论   18篇
预防医学   3158篇
眼科学   411篇
药学   1396篇
中国医学   13篇
肿瘤学   1779篇
  2023年   360篇
  2022年   608篇
  2021年   1273篇
  2020年   751篇
  2019年   1054篇
  2018年   1132篇
  2017年   774篇
  2016年   803篇
  2015年   872篇
  2014年   1112篇
  2013年   1386篇
  2012年   2085篇
  2011年   2009篇
  2010年   964篇
  2009年   807篇
  2008年   1320篇
  2007年   1216篇
  2006年   1044篇
  2005年   850篇
  2004年   735篇
  2003年   644篇
  2002年   535篇
  2001年   260篇
  2000年   243篇
  1999年   234篇
  1998年   114篇
  1997年   95篇
  1996年   62篇
  1995年   58篇
  1994年   61篇
  1993年   60篇
  1992年   160篇
  1991年   166篇
  1990年   163篇
  1989年   161篇
  1988年   156篇
  1987年   128篇
  1986年   146篇
  1985年   138篇
  1984年   120篇
  1983年   128篇
  1982年   63篇
  1980年   59篇
  1979年   88篇
  1978年   67篇
  1976年   55篇
  1974年   69篇
  1973年   57篇
  1971年   57篇
  1970年   51篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Mildly elevated maternal plasma homocysteine (Hcy) levels (hyperhomocysteinemia) have recently been observed in some neural tube defect (NTD) pregnancies. Plasma levels of Hcy are governed by both genetic and nutritional factors and the aetiology of NTDs is also known to have both genetic and nutritional components. We therefore examined the frequency of relatively common mutations in the enzyme cystathionine β-synthase (CBS), which is one of the main enzymes that controls Hcy levels, in the NTD population. Neither the severely dysfunctional G307S CBS allele nor the recently reported 68 bp insertion/I278T CBS allele was observed at increased frequency in the cases relative to controls. We therefore conclude that loss of function CBS alleles do not account for a significant proportion of NTDs in Ireland.  相似文献   
32.
33.
Throughout most medical careers the practical aspects of dealingwith tracheostomies are an ignored but simultaneously fearedaspect of patient care. They are generally regarded as someoneelse's business, right up to the point when a disaster occurs.Even when the patient is breathless and needing help many healthpractitioners of all types fear to step in and execute  相似文献   
34.
BACKGROUND: The process of gastro-duodenal digestion may play a role in determining the allergenic properties of food proteins. The sensitizing and allergenic potential of digestion products of highly degraded allergens, such as the major peanut allergen Ara h 1, is currently under debate. We evaluated the effect of in vitro gastro-duodenal digestion of Ara h 1 on T cell reactivity and basophil histamine release. METHODS: An in vitro model of gastro-duodenal digestion was used to investigate changes in the allergenic properties of Ara h 1 using in vitro assays monitoring T cell reactivity (proliferation, cytokine production) and histamine release of basophils from peanut allergic individuals. The digestion process was monitored using an SDS-PAGE gel. RESULTS: In vitro gastric digestion led to rapid degradation of Ara h 1 into small fragments M(r) L5600. Gastric digestion did not affect the ability of Ara h 1 to stimulate cellular proliferation. Gastro-duodenal digestion significantly reduced its ability to stimulate clonal expansion (P<0,05; Wilxocon's signed rank test). The Th-2 type cytokine polarization of T cells from peanut allergic donors (IFN-gamma/IL-13 ratio and IFN-gamma/IL-4 ratio of CFSE(low) CD4(+) T cells) remained unchanged regardless of the level of digestion. Histamine release of basophils from peanut allergic individuals was induced to the same extent by native Ara h 1 and its digestion products. CONCLUSION: Gastro-duodenal digestion fragments of Ara h 1 retain T cell stimulatory and IgE-binding and cross-linking properties of the intact protein.  相似文献   
35.
The authors report the occurrence and clinical course of serous retinal detachment following glaucoma surgery in three patients. Serous detachment resolved in all patients spontaneously following treatment with oral and topical steroids.  相似文献   
36.
This study is a retrospective review of nine patients who sustained isolated fractures of the lateral process of the talus. The majority were caused by inversion or a combination of inversion and dorsiflexion of the foot. Following a review of the literature and anatomical dissections the authors recommend a classification based on anterior-posterior tomography of the talus, into intra- and extra-articular fractures.  相似文献   
37.
The major limitation in adult-to-adult living donor liver transplantation (LDLT) is an adequate graft size with special regard to the safety of the donor. Only 20% of the evaluated donors are suitable to donate the right liver, depending mainly on the critical remnant liver volume. We report 2 cases of adult-to-adult LDLT using dual grafts. In the first case we implanted a left lateral lobe together with a left lobe; in the second case we used a left lateral and a right lobe. Dual graft LDLT solves the problem of graft-size insufficiency and avoids critical right lobectomy in the donor. This procedure can be safely performed and opens up the possibility of LDLT to even more families in the Western world.  相似文献   
38.
目的:研究葡萄膜黑色素瘤^125I板放射治疗后与脂质渗出相关的因素。设计:回顾性、干预性、病例系列研究。方法:回顾139例用^125I板放射治疗的葡萄膜黑色素瘤的连续患者的病历记录,脂质渗出作为主要的测量结果。结果:19例患者检出有脂质渗出(13.7%),从放射治疗到脂质渗出的平均时间为10个月(极差3~23个月)。脂质渗出与患者年龄较低(P=0.0002)、低密度脂蛋白增加(P=0.004)、高密度脂蛋白减少(P=0.026)、肿瘤体积增加(P=0.024)及渗出性视网膜脱离(P=0.016)相关。脂质渗出患者伴有视力差(P〈0.0001)及新生血管性青光眼增加(P=0.01)。结论:葡萄膜黑色素瘤^125I板放射治疗后的脂质渗出与眼部预后差相关。脂质渗出相关的因素与辐射性视网膜病变的相关因素完全不同,这些因素为治疗并发症提供依据。  相似文献   
39.
40.
In recent trials in The Gambia, mass chemoprophylaxis with Maloprim administered over several years by primary health care workers to children aged 3-59 months has reduced both mortality and morbidity without inducing impairment of natural immunity or significant development of drug resistance. Taking expenditure of both time and money, by both public authorities and village volunteers, into account, the costs and the cost effectiveness of such mass chemoprophylaxis are estimated here. The cost per child protected per season was (1990 US) $2.84; the cost per childhood death averted was $143. Both costs compare favourably with those of permethrin bed net impregnation. So in some circumstances where malaria is holoendemic, control of childhood malaria by chemoprophylaxis may be more economically efficient than provision of impregnated bed nets.  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