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   9506篇
  免费   592篇
  国内免费   36篇
耳鼻咽喉   119篇
儿科学   257篇
妇产科学   177篇
基础医学   1377篇
口腔科学   1073篇
临床医学   637篇
内科学   1906篇
皮肤病学   219篇
神经病学   571篇
特种医学   328篇
外科学   953篇
综合类   87篇
一般理论   3篇
预防医学   967篇
眼科学   307篇
药学   659篇
中国医学   108篇
肿瘤学   386篇
  2024年   18篇
  2023年   86篇
  2022年   199篇
  2021年   358篇
  2020年   224篇
  2019年   314篇
  2018年   386篇
  2017年   236篇
  2016年   297篇
  2015年   359篇
  2014年   448篇
  2013年   523篇
  2012年   787篇
  2011年   780篇
  2010年   426篇
  2009年   369篇
  2008年   542篇
  2007年   544篇
  2006年   441篇
  2005年   375篇
  2004年   403篇
  2003年   290篇
  2002年   225篇
  2001年   161篇
  2000年   133篇
  1999年   131篇
  1998年   98篇
  1997年   72篇
  1996年   64篇
  1995年   57篇
  1994年   34篇
  1993年   39篇
  1992年   45篇
  1991年   50篇
  1990年   51篇
  1989年   60篇
  1988年   62篇
  1987年   60篇
  1986年   51篇
  1985年   48篇
  1984年   24篇
  1983年   36篇
  1981年   23篇
  1980年   19篇
  1978年   14篇
  1977年   14篇
  1976年   21篇
  1975年   14篇
  1974年   14篇
  1973年   17篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Paired maternal and newborn urine and amniotic fluid from 138 subjects collected during a Zika virus (ZIKV) outbreak was analyzed for ZIKV by gene amplification (RT-qPCR), and the findings were correlated with clinical symptoms and neurological anomalies in the babies. ZIKV was detected in 1 of 9 symptomatic women (11.1%) and in 19 of 129 asymptomatic women (14.7%). Neurological manifestations were present in 19 babies (13.7%), 10 of 20 (50%) positive and 9 of 119 (7.6%) negative (p < 0.001) for ZIKV. Twelve (8.6%) urines collected during gestation were ZIKV-positive; only 2 remained positive for ZIKV postpartum. Six (4.1%) newborn urines collected within 1 day of delivery were ZIKV-positive cases. In 3 of these cases, ZIKV was detected in mother’s urine pre- and postpartum and in both mother’s urine and babies’ urine. Four of the amniotic fluid samples (2.9%) were ZIKV-positive. Among ZIKV-negative babies with neurological sequel, 87.5% were female; in contrast, 72.7% ZIKV-positive babies with neurological abnormalities were male (p = 0.019). We conclude that during a ZIKV outbreak, clinical symptoms and ZIKV detection in biological fluids are poor predictors of infection and adverse neurologic sequel in newborns.  相似文献   
103.
Excessive sugar intake represents an increased risk of developing non-communicable diseases (e.g., obesity, cardiometabolic diseases, and dental diseases). Still, it is unclear whether people are aware of these adverse health outcomes. The current study systematically examined the extent to which people associate health conditions with excessive sugar intake. Participants (N = 1010 Portuguese volunteers) freely reported all health conditions they associated with excessive sugar consumption and rated the strength of these associations for eight specific health conditions. All participants reported health conditions associated with excessive sugar intake, with the most frequent being risk factors for cardiometabolic diseases (e.g., diabetes), cardiovascular diseases, oral problems, oncological and mental health conditions. Moreover, participants considered diabetes, overweight/obesity, and oral problems as being the conditions most related to excessive sugar intake. Women, participants with children in the household, and experts in health/nutrition rated excessive sugar intake as being more strongly linked to some of the health conditions. The identification of the health conditions that people associate with excessive sugar consumption may inform policymakers, educators, and health professionals and support interventions targeting the general public or specific groups (e.g., overweight people) in raising awareness of potential adverse health outcomes and, ultimately, contribute to reducing sugar intake.  相似文献   
104.
Blend films based on sodium alginate (SA) and citrus pectin (P) reinforced with different concentrations of SiO2 (0–10% w/w) were developed in this study. From the morphological (SEM) and structural (FT-IR) evaluation, it was verified that the incorporation of the reinforcing agent did not drastically modify the microstructure of the films, nor did new chemical bonds form. However, the XRD results suggested a slight reduction in the crystallinities of the blends by the incorporation of SiO2. Among the formulations prepared, the addition of a 5% reinforcing agent was responsible for the simultaneous improvement of mechanical and barrier properties. Comparing the control sample (SA/P) with the SA/P/5.0%SiO2 film, the tensile strength increased from 27.7 ± 3.7 to 40.6 ± 4.5 MPa, and the water-vapor transmission rate decreased from 319.8 ± 38.7 to 288.9 ± 23.5 g m−2 day−1. Therefore, SiO2, as a reinforcing agent in SA/P blends, represents a simple and effective strategy for improving the properties of biopolymer-based films in applications, such as packaging.  相似文献   
105.
<正>To the Editor:Ischemia-reperfusion injury following surgery and transplantation can lead to irreversible multiorgan failure.Intracellular calcium overload is associated to cellular death during ischemiareperfusion.A recently discovered heparin fragment (HF),trisulfated disaccharide (TD),that acts on sodium-calcium exchanger(NCX) decreasing intracellular Ca2+,showed effectiveness on protecting hepatocytes from ischemia-reperfusion injury [1],  相似文献   
106.
107.
Titanium oxide (TiO2) has been widely investigated as a photocatalytic material, and the fact that its performance depends on its crystalline structure motivates further research on the relationship between preparation methods and material properties. In this work, TiO2 thin films were grown on non-functionalized wave-like patterned vertically aligned carbon nanotubes (w-VA-CNTs) via the atomic layer deposition (ALD) technique. Grazing incidence X-ray diffraction (GIXRD) analysis revealed that the structure of the TiO2/VA-CNT nanocomposites varied from amorphous to a crystalline phase with increasing deposition temperature, suggesting a “critical deposition temperature” for the anatase crystalline phase formation. On the other hand, scanning transmission electron microscopy (STEM) studies revealed that the non-functionalized carbon nanotubes were conformally and homogeneously coated with TiO2, forming a nanocomposite while preserving the morphology of the nanotubes. X-ray photoelectron spectroscopy (XPS) provided information about the surface chemistry and stoichiometry of TiO2. The photodegradation experiments under ultraviolet (UV) light on a model pollutant (Rhodamine B, RhB) revealed that the nanocomposite comprised of anatase crystalline TiO2 grown at 200 °C (11.2 nm thickness) presented the highest degradation efficiency viz 55% with an illumination time of 240 min. Furthermore, its recyclability was also demonstrated for multiple cycles, showing good recovery and potential for practical applications.

Amorphous or anatase crystalline TiO2/VA-CNT nanocomposites were grown controlling the synthesis temperature. Photocatalytic degradation of RhB of 55% was achieved after 240 min. The immobilized material remains active after 4 cycles of use.  相似文献   
108.
Comparison of cardiac function in male and female diabetic rats   总被引:1,自引:0,他引:1  
To examine the influence of sex differences in the STZ model of diabetes, we studied left ventricular function in hearts from 6 week old male and female rats. Significantly lower values for +dP/dt occurred in male diabetic rats compared with their own controls or female diabetics at most left atrial filling pressures. Decreases in this value for female diabetic rats compared to their own controls occurred only at high left atrial pressures. It appears that diabetes mellitus produces greater myocardial dysfunction in male diabetic rats.  相似文献   
109.
Anterior clear spaces were observed prospectively at slit-lamp examination in 26 of 69 consecutive eyes (38%) with keratoconus. Two corneal buttons with this finding were examined by light and electron microscopy and revealed breaks in Bowman's layer. Anterior clear spaces should be considered in the spectrum of clinical findings in keratoconus.  相似文献   
110.
Longitudinal studies evaluating the relationship between UPF consumption and the incidence of Metabolic Syndrome (MetS) and its components are still scarce. This study aimed to evaluate the effect of UPF consumption on the incidence of MetS and its components in adults. A prospective study was conducted with 896 participants from the 1978/79 Ribeirão Preto cohort, São Paulo, Brazil. UPF consumption was evaluated in %kcal and %g at ages 23–25 years. Incidence of MetS and its components were estimated at ages 37–39 years, according to the Joint Interim Statement criteria. Poisson regression was used to assess associations, and interactions with sex were investigated. UPF consumption had no association with MetS (%kcal Adjusted PR: 1.00; 95% CI: 0.99–1.01; %g Adjusted PR: 1.00; 95% CI: 0.99–1.01). However, women with higher UPF consumption, in %kcal and %g, had a higher risk of abdominal obesity (%kcal: p = 0.030; %g: p = 0.003); and women with higher UPF consumption, in %g, had a higher risk of low HDL-cholesterol (p = 0.041). For the other components of MetS, no significant associations were observed in either sex. These findings suggest evidence of no association between UPF consumption and MetS; however, consumption of UPF was associated with increased WC and low HDL-c, but only in women.  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