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   172388篇
  免费   11827篇
  国内免费   550篇
耳鼻咽喉   2652篇
儿科学   4948篇
妇产科学   5117篇
基础医学   20902篇
口腔科学   5655篇
临床医学   24629篇
内科学   39650篇
皮肤病学   5006篇
神经病学   13018篇
特种医学   3652篇
外国民族医学   2篇
外科学   19660篇
综合类   994篇
一般理论   43篇
预防医学   16738篇
眼科学   3361篇
药学   10931篇
中国医学   872篇
肿瘤学   6935篇
  2023年   1672篇
  2022年   1692篇
  2021年   4352篇
  2020年   2628篇
  2019年   4118篇
  2018年   6674篇
  2017年   4629篇
  2016年   4538篇
  2015年   5002篇
  2014年   6242篇
  2013年   8569篇
  2012年   11195篇
  2011年   12288篇
  2010年   7127篇
  2009年   6038篇
  2008年   9580篇
  2007年   10010篇
  2006年   9316篇
  2005年   9180篇
  2004年   8214篇
  2003年   7611篇
  2002年   7030篇
  2001年   4846篇
  2000年   5228篇
  1999年   4285篇
  1998年   1399篇
  1997年   1320篇
  1996年   1162篇
  1995年   1023篇
  1994年   777篇
  1993年   630篇
  1992年   1737篇
  1991年   1474篇
  1990年   1356篇
  1989年   1101篇
  1988年   936篇
  1987年   865篇
  1986年   865篇
  1985年   779篇
  1984年   556篇
  1983年   480篇
  1979年   502篇
  1978年   346篇
  1975年   335篇
  1974年   413篇
  1973年   413篇
  1972年   410篇
  1971年   361篇
  1970年   326篇
  1969年   347篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
112.
113.
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   
114.
115.

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   
116.
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   
117.
118.
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   
119.
Carcinosarcomas are biphasic tumors composed of admixed malignant epithelial and mesenchymal components. Numerous terms have been used to name such neoplasms; therefore, terminological confusion is frequent. Most examples of carcinosarcomas are encountered in non‐cutaneous sites, with approximately 100 cases of cutaneous carcinosarcomas reported so far in the English literature. Although different theories have been suggested to explain the occurrence of these peculiar neoplasms, histogenetic mechanisms should be better hypothesized depending on each individual case. Even though prognosis tends to be related to the specific components of the lesion, especially the epithelial one, it seems that cases of cutaneous localization usually have a better outcome. We report an exceedingly rare case of syringocystadenocarcinoma papilliferum which showed an atypical stroma with sarcomatoid appearance, and highlight that the terminology used for this spectrum of lesions is disorganized and confusing.  相似文献   
120.
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