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   107559篇
  免费   10459篇
  国内免费   3223篇
耳鼻咽喉   894篇
儿科学   1244篇
妇产科学   1039篇
基础医学   12202篇
口腔科学   3734篇
临床医学   11129篇
内科学   11520篇
皮肤病学   1334篇
神经病学   6794篇
特种医学   3267篇
外国民族医学   11篇
外科学   7606篇
综合类   15366篇
现状与发展   8篇
一般理论   3篇
预防医学   18696篇
眼科学   1254篇
药学   14357篇
  121篇
中国医学   5817篇
肿瘤学   4845篇
  2024年   427篇
  2023年   2036篇
  2022年   4170篇
  2021年   5246篇
  2020年   5061篇
  2019年   4452篇
  2018年   4095篇
  2017年   4325篇
  2016年   4313篇
  2015年   4230篇
  2014年   7361篇
  2013年   8009篇
  2012年   7066篇
  2011年   7439篇
  2010年   5577篇
  2009年   5178篇
  2008年   4964篇
  2007年   4958篇
  2006年   4210篇
  2005年   3692篇
  2004年   3073篇
  2003年   2802篇
  2002年   2207篇
  2001年   2076篇
  2000年   1618篇
  1999年   1418篇
  1998年   1350篇
  1997年   1204篇
  1996年   1056篇
  1995年   941篇
  1994年   894篇
  1993年   706篇
  1992年   655篇
  1991年   561篇
  1990年   484篇
  1989年   493篇
  1988年   423篇
  1987年   370篇
  1986年   286篇
  1985年   378篇
  1984年   300篇
  1983年   176篇
  1982年   203篇
  1981年   155篇
  1980年   157篇
  1979年   116篇
  1978年   77篇
  1977年   51篇
  1976年   74篇
  1974年   41篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Precise data on food chemical composition is crucial for any quantitative nutrition research and indispensable for evaluation and planning of computer-based menus. Moreover, exact food chemical composition is of the utmost importance in composing specific diets that may be low in certain essential nutrients. Therefore, this research evaluated a weekly vegan menu using three different food composition databases (FCDB): the Croatian, the official Danish Food Composition Database and the United States Department of Agriculture (USDA) – National Nutrient Database for Standard Reference. Significant differences (p < 0.05) were determined in evaluated and optimised offers for the same menu when using different FCDBs. Furthermore, in these menus quantities of some nutrients have not reached official daily recommendations needed for prevention of non-communicable diseases. In this research, new vegan menus that can provide adequate quantity of essential nutrients, regardless of FCDB utilized, were created with linear optimisation (LO). This resulted in high quality daily menu offers. However, depending on the FCDB that was used, optimal menus differed in daily meal combinations, and the effectiveness of the optimisation in the minimisation of differences caused by differences of data in FCDBs was tested. Linear optimisation has been proved to be an effective tool in planning of specific diets, such as vegan diets. Nonetheless, the quality of computer-planned menus depends heavily on the quality of FCDB used.  相似文献   
13.
14.
15.
16.
BackgroundCarbetocin has been found to be superior to oxytocin in terms of need for additional uterotonics and prevention of postpartum haemorrhage at caesarean delivery. However, this is based on combined data from labouring and non-labouring parturients and it remains unclear how effective carbetocin is in the purely elective setting. The aim of this review was to compare carbetocin to oxytocin in elective caesarean delivery.MethodsMedline, Embase, CINAHL, Web of Science, and the Cochrane databases were searched for randomised controlled trials in any language. The primary outcome was need for additional uterotonics. Secondary outcomes were mean blood loss, need for blood transfusion and incidence of postpartum haemorrhage >1000 mL.ResultsNine studies with a total of 1962 patients were included. Trial sequential analysis confirmed that the information size (n=1692) had surpassed that required (n=1166) in order to demonstrate a statistically significant reduction in the use of additional uterotonics. Need for additional uterotonics was reduced by 53% with carbetocin compared to oxytocin (OR 0.47, 95% CI 0.34 to 0.64; P <0.001, I2=63.5). The number needed-to-treat was 11. The risk of bias, data heterogeneity and inconsistency in reporting bleeding outcomes made it difficult to reach definite conclusions about prevention of PPH.ConclusionsCarbetocin is associated with a reduced need for additional uterotonics when compared with oxytocin at elective caesarean delivery. Standardisation of bleeding-related outcomes in studies is necessary to facilitate synthesis of data in future analyses.  相似文献   
17.
To increase the overall rate of breastfeeding initiation and duration, factors involved in a mother's decision to breastfeed must be identified. Self‐objectification in the context of breastfeeding was a concept selected for exploring factors associated with negative views of breastfeeding. A concept analysis following the eight‐step Walker & Avant method provides clarity and context to the concept of self‐objectification in the context of breastfeeding. The antecedents of self‐objectification in the context of breastfeeding include living in a culture of sexualization and objectification of women and the internalization of the values of objectification. Attributes of self‐objectification in the context of breastfeeding are a prioritization of physical appearance attributes of the breast over the health benefits of breastfeeding and a preoccupation with physical appearance. Consequences include negative views toward breastfeeding initiation, duration, and public breastfeeding. A concept analysis on self‐objectification in the context of breastfeeding will provide definition and clarity to this phenomenon, lend to theory and measurement, and add literature to the sociocultural factors impacting breastfeeding decisions.  相似文献   
18.
19.
《Vaccine》2020,38(33):5337-5342
Freezing of alum-based vaccines drastically alters their colloidal composition and leads to irreversible cluster formation. The loss of stability is well described, but the impact of frost damage on the functionality of the induced and secreted antibody repertoire has not been studied in detail. We therefore applied our single-cell measurement platform to extract the frequencies of Immunoglobulin G-secreting cells in combination with individual secretion rates and affinities. We showed that, frost-damaged or not, the tested vaccine was able to generate similar frequencies of total and antigen-affine IgG-secreting cells. Additionally, the frost-damaged vaccine stimulated a similar T-cell cytokine secretion pattern when compared to the regularly stored vaccine. However, frost-damaged vaccines induced no efficient affinity maturation and a complete collapse of the affinity distribution was observed. This study unveiled the impact of frost-damage to alum-based vaccines on the induced secreted antibody repertoire, and illustrated the power of functional single-antibody analysis.  相似文献   
20.
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