首页 | 官方网站   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   5340篇
  免费   325篇
  国内免费   73篇
医药卫生   5738篇
  2024年   10篇
  2023年   94篇
  2022年   67篇
  2021年   287篇
  2020年   216篇
  2019年   230篇
  2018年   241篇
  2017年   154篇
  2016年   220篇
  2015年   232篇
  2014年   273篇
  2013年   352篇
  2012年   497篇
  2011年   468篇
  2010年   259篇
  2009年   224篇
  2008年   289篇
  2007年   313篇
  2006年   251篇
  2005年   234篇
  2004年   228篇
  2003年   196篇
  2002年   143篇
  2001年   25篇
  2000年   11篇
  1999年   19篇
  1998年   36篇
  1997年   28篇
  1996年   21篇
  1995年   17篇
  1994年   15篇
  1993年   14篇
  1992年   16篇
  1991年   11篇
  1990年   10篇
  1989年   4篇
  1988年   3篇
  1987年   5篇
  1986年   5篇
  1984年   2篇
  1982年   4篇
  1978年   1篇
  1977年   1篇
  1973年   3篇
  1964年   1篇
  1962年   1篇
  1961年   1篇
  1957年   1篇
  1940年   1篇
  1905年   1篇
排序方式: 共有5738条查询结果,搜索用时 31 毫秒
991.
Nutrition and immunity are closely related, and the immune system is composed of the most highly energy-consuming cells in the body. Much of the immune system is located within the GI tract, since it must deal with the huge antigenic load introduced with food. Moreover, the incidence of immune-mediated diseases is elevated in Westernized countries, where “transition nutrition” prevails, owing to the shift from traditional dietary patterns towards Westernized patterns. This ecological correlation has fostered increasing attempts to find evidence to support nutritional interventions aimed at managing and reducing the risk of immune-mediated diseases. Recent studies have described the impacts of single nutrients on markers of immune function, but the knowledge currently available is not sufficient to demonstrate the impact of specific dietary patterns on immune-mediated clinical disease endpoints. If nutritional scientists are to conduct quality research, one of many challenges facing them, in studying the complex interactions between the immune system and diet, is to develop improved tools for investigating eating habits in the context of immunomediated diseases.  相似文献   
992.
993.
994.
Given the frequency and persistence of human papillomavirus (HPV) infection and associated cytological alterations in HIV-1-positive women, the incidence of uterine cervix neoplasm is likely to increase along with patient survival. More appropriate screening programs, which, in addition to Pap smears (PS), also include tests to detect and type HPV, are needed for the early identification of precancerous cervical lesions. This prospective study involved 168 HIV-positive (group A) and 100 HIV-negative women (group B). Cervicovaginal samples were collected for a PS and HPV DNA search. The detected virus was typed as high–intermediate oncogenic risk HPV (HR-HPV) and low-risk HPV (LR-HPV) using hybrid capture (HC) (Murex-Digene) and in-house PCR tests. The HC-detected prevalence of HPV was 111/168 (66%:HR 75.6%) in group A and 15/100 (15%:HR 42.9%) in group B (P < 0.0001). Polymerase chain reaction (PCR) was positive in 91% and 48%, respectively. No significant difference was observed between drug addicts and heterosexual HIV-1-positive women (P = 0.09). HPV was detected in 94% of the 57 HIV-positive women with cytological alterations. HR-HPV was found in 41/49 women with low-grade and 7/8 with high-grade squamous intraepithelial lesions (LSIL and HSIL, respectively). In women with a negative PS, HPV was detected in 57/111 cases (HR 63%) of group A and in 13/98 of group B (6 cases of HR). Of the 54 group A women who underwent biopsy, histology revealed that 41 had LSIL (18 with negative PS, 19 with LSIL, and 4 with HSIL; HR-HPV in 73% and LR-HPV in 17%), nine had HSIL (5 LSIL and 4 HSIL on cytology; HR-HPV in 89% and LR-HPV in 11%), and four were negative (all cytology negative; 3 HR-HPV and 1 LR-HPV). HR-HPV was more frequent as immunodepression worsened. These results show that cytological evaluation alone underestimated histological alterations in 23/50 women (42.6%), whereas the combination of Pap smear and HPV detection reduced this underestimate to 5%. J. Med. Virol. 56:133–137, 1998. © 1998 Wiley-Liss, Inc.  相似文献   
995.
The liver is the major drug-metabolizing and drug-detoxifying organ. Many drugs can cause liver damage through various mechanisms; however, the liver response to injury includes a relatively narrow spectrum of alterations that, regardless of the cause, are represented by phlogosis, oxidative stress and necrosis. The combination of these alterations mainly results in three radiological findings: vascular alterations, structural changes and metabolic function reduction. Chemotherapy has changed in recent decades in terms of the drugs, protocols and duration, allowing patients a longer life expectancy. As a consequence, we are currently observing an increase in chemotherapy-associated liver injury patterns once considered unusual. Recognizing this form of damage in an early stage is crucial for reconsidering the therapy regimen and thus avoiding severe complications. In this frontier article, we analyze the role of imaging in detecting some of these pathological patterns, such as pseudocirrhosis, “yellow liver” due to chemotherapy-associated steatosis-steatohepatitis, and “blue liver”, including sinusoidal obstruction syndrome, veno-occlusive disease and peliosis.  相似文献   
996.
997.
998.
Organic field-effect transistors (FETs) can be applied to radio-frequency identification tags (RFIDs) and active-matrix flat-panel displays. For RFID application, a cardinal functional block is a ring oscillator using an odd number of inverters to convert DC voltage to AC. Herein, we report the properties of two ring oscillators, one formed with [6]phenacene for a p-channel FET and N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) for an n-channel FET, and one formed with 3,10-ditetradecylpicene ((C14H29)2-picene) for a p-channel FET and PTCDI-C8 for an n-channel FET. The former ring oscillator provided a maximum oscillation frequency, fosc of 26 Hz, and the latter a maximum fosc of 21 Hz. The drain–drain voltage, VDD, applied to these ring oscillators was 100 V. This may be the first step towards a future practical ring oscillator using phenacene molecules. The values of field-effect mobility, μ in the p-channel [6]phenacene FET and n-channel PTCDI-C8 FET, which form the building blocks in the ring oscillator with an fosc value of 26 Hz, are 1.19 and 1.50 × 10−1 cm2 V−1 s−1, respectively, while the values in the p-channel (C14H29)2-picene FET and n-channel PTCDI-C8 FET, which form the ring oscillator with an fosc of 21 Hz, are 1.85 and 1.54 × 10−1 cm2 V−1 s−1, respectively. The μ values in the p-channel FETs are higher by one order of magnitude than those of the n-channel FET, which must be addressed to increase the value of fosc. Finally, we fabricated a ring oscillator with ZrO2 instead of parylene for the gate dielectric, which provided the low-voltage operation of the ring oscillator, in which [6]phenacene and PTCDI-C8 thin-film FETs were employed. The value of fosc obtained in the ring oscillator was 24 Hz. In this ring oscillator, the VDD value applied was limited to 20 V. The durability of the ring oscillators was also investigated, and the bias stress effect on the fosc and the amplitude of the output voltage, Vout are discussed. This successful operation of ring oscillators represents an important step towards the realization of future practical integrated logic gate circuits using phenacene molecules.

A ring oscillator consisting of p-channel and n-channel organic FETs.  相似文献   
999.
The isolation of three adenosine based metabolites 6–8 from Streptomyces calvus is reported. The metabolites are structurally related to the fluorine containing antibiotic nucleocidin 1 and two recently identified glycosylated fluoroadenosines 2 and 3, however in this case the three metabolites do not contain a fluorine, suggesting that the biosynthetic enzymes to the fluorometabolites also process their non-fluorinated counterparts.

The isolation of three adenosine based metabolites 6–8 from Streptomyces calvus is reported.  相似文献   
1000.
Introduction:Despite advances in the management of type 1 diabetes (T1D), there is an increasing incidence of skin reactions related to diabetes devices such as patch pumps and glucose sensors. Aim of the present study was to assess the prevalence of dermatological complications in pediatric patients with T1D using technological devices.Methods:Online survey regarding skin reactions related to the use of patch pumps and/or glucose sensors was administered to families of children and adolescents (0-17 years) with T1D. Data were collected on demographic characteristics, duration of diabetes, and clinical features of dermatological complications if present.Results:Our study population consisted of 139 patients (female 51.8%) aged 11.1 ± 3.3 years. More than half (51.1%) experienced skin reactions due to patch pumps or glucose sensors. Dermatological complications were mainly caused by continuous glucose monitoring (56.3% of total). Timing of appearance of dermatological reactions varied from a few days to several months after the introduction of the device. The application of hypoallergenic barrier bandages was the most frequently adopted measure to solve the issue.Conclusions:Our study confirmed high frequency of dermatological complications among pediatric patients with type 1 diabetes. Well-designed studies are awaited to provide clear recommendations to minimize the burden of skin issues related to technological devices.  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-23

京公网安备 11010802026262号