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   201476篇
  免费   9890篇
  国内免费   564篇
耳鼻咽喉   2946篇
儿科学   6226篇
妇产科学   4907篇
基础医学   28187篇
口腔科学   6601篇
临床医学   13364篇
内科学   48085篇
皮肤病学   6491篇
神经病学   16711篇
特种医学   4924篇
外国民族医学   30篇
外科学   25285篇
综合类   1094篇
一般理论   57篇
预防医学   18816篇
眼科学   4026篇
药学   14086篇
中国医学   878篇
肿瘤学   9216篇
  2023年   1106篇
  2022年   1155篇
  2021年   4659篇
  2020年   2448篇
  2019年   4574篇
  2018年   6549篇
  2017年   4063篇
  2016年   4024篇
  2015年   4377篇
  2014年   5778篇
  2013年   8355篇
  2012年   13316篇
  2011年   14012篇
  2010年   7448篇
  2009年   6120篇
  2008年   11443篇
  2007年   12146篇
  2006年   11476篇
  2005年   11373篇
  2004年   10215篇
  2003年   9698篇
  2002年   9149篇
  2001年   6015篇
  2000年   6525篇
  1999年   5226篇
  1998年   1380篇
  1997年   1006篇
  1996年   909篇
  1995年   785篇
  1994年   615篇
  1993年   602篇
  1992年   2299篇
  1991年   2092篇
  1990年   1887篇
  1989年   1628篇
  1988年   1443篇
  1987年   1395篇
  1986年   1330篇
  1985年   1192篇
  1984年   892篇
  1983年   764篇
  1979年   793篇
  1978年   540篇
  1975年   607篇
  1974年   682篇
  1973年   729篇
  1972年   627篇
  1971年   629篇
  1970年   607篇
  1969年   597篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
92.
Serum lactate is a non-specific marker of tissue hypoperfusion. Elevated serum lactate is used in the differential diagnosis of acute intestinal ischemia. Although this practice is controversial, in the absence of other validated markers lactate is still used because of its high sensitivity.We present the cases of two patients who developed acute mesenteric ischemia as a post-surgical complication. The patients reported moderate abdominal pain —a non-specific symptom in the postoperative context— and tests showed progressively increasing serum lactate levels, which facilitated suspicion and subsequent diagnostic confirmation through an imaging test.These cases highlight the physiopathological importance of lactate elevation in the perioperative context and of performing a differential diagnosis of its possible causes, including mesenteric ischemia. Although the outcome was negative in the first case, early suspicion allowed us to make an effective diagnosis and administer appropriate treatment in the second patient.  相似文献   
93.
94.
95.

Objective

To analyse and understand vaccination hesitancy discourses, particularly those of people who have decided not to vaccinate their sons and daughters.

Methods

Qualitative study of five individual interviews and two focus groups with people who chose not to vaccinate their children in the province of Granada (Spain).

Results

Mothers and fathers manifest a system of health beliefs different to the biomedical paradigm. From an ethical point of view, they justify their position based on the right to autonomy and responsibility for their decisions. Alleged specific reasons: they doubt administration of several vaccines simultaneously at an early age in a systematic way and without individualising each case; they fear adverse effects and do not understand the variations of the vaccination schedule.

Conclusions

These vaccination hesitancy discourses respond to the individual vs collective conflict; parents defend their right to bring up their children without any interference from the state and focus their responsibility on the individual welfare of their sons and daughters, regardless of the consequences that their actions might have on the collective. In their management of risks, they consider those derived from vaccination more relevant than the individual or collective consequences of not doing so. The vaccines generating most doubts are the more controversial ones within the scientific world. Transparency in communication of adverse effects; authorities respect for other health/disease concepts; banishment of the term “anti-vaccines” from the media and scientific vocabulary, and developing spaces for dialogue are bridges to be built.  相似文献   
96.
IntroductionPeople with Down syndrome (DS) have high respiratory morbidity, evaluating their respiratory health with standardized, objective tests is desirable. Thus, the objective of this study was to evaluate the technical quality of Pulmonary Function Tests (PFTs) to determine which ones are most suitable for this population.MethodsParticipants included children, teenagers and adults with DS, 5 years of age or older (n = 302). The technical quality of the impulse oscillometry system (IOS), forced spirometry, lung-diffusing capacity for carbon monoxide (DLCO), and 6-min walk test (6MWT) were analyzed by age group. Capnography and pulse oximetry were included in the study. Technical quality was determined on the basis of current international PFTs standards.ResultsFifty-one percent of participants were males. A total of 184 participants (71%) who completed the IOS fulfilled the quality criteria, while 210 (70%) completed the 6MWT. Performance on forced spirometry and DLCO was poor. All pulse oximetries and 96% percent heart rates obtained had good quality, but exhaled carbon dioxide (PetCO2) and respiratory rate (RR) showed deficient repeatability.ConclusionsIOS appears to be the most reliable instrument for evaluating lung mechanics in individuals with DS.  相似文献   
97.
98.
99.
100.
Isotactic polypropylenes (iPP) with different melt flow indexes (MFI) were used to fabricate nanocomposites (NCs) with 10 wt % loadings of multi-wall carbon nanotubes (MWCNTs) using ultrasound-assisted extrusion methods to determine their effect on the morphology, melt flow, and electrical properties of the NCs. Three different types of iPPs were used with MFIs of 2.5, 34 and 1200 g/10 min. Four different NC fabrication methods based on melt extrusion were used. In the first method melt extrusion fabrication without ultrasound assistance was used. In the second and third methods, an ultrasound probe attached to a hot chamber located at the exit of the die was used to subject the sample to fixed frequency and variable frequency, respectively. The fourth method is similar to the first method, with the difference being that the carbon nanotubes were treated in a fluidized air-bed with an ultrasound probe before being used in the fabrication of the NCs with no ultrasound assistance during extrusion. The samples were characterized by MFI, Optical microscopy (OM), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), electrical surface resistivity, and electric charge. MFI decreases in all cases with addition of MWCNTs with the largest decrease observed for samples with the highest MFI. The surface resistivity, which ranged from 1013 to 105 Ω/sq, and electric charge, were observed to depend on the ultrasound-assisted fabrication method as well as on the melt flow index of the iPP. A relationship between agglomerate size and area ratio with electric charge was found. Several trends in the overall data were identified and are discussed in terms of MFI and the different fabrication methods.  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