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   2585篇
  免费   190篇
  国内免费   25篇
耳鼻咽喉   12篇
儿科学   67篇
妇产科学   105篇
基础医学   345篇
口腔科学   75篇
临床医学   266篇
内科学   634篇
皮肤病学   70篇
神经病学   174篇
特种医学   78篇
外科学   256篇
综合类   27篇
一般理论   1篇
预防医学   177篇
眼科学   76篇
药学   155篇
中国医学   16篇
肿瘤学   266篇
  2024年   3篇
  2023年   45篇
  2022年   74篇
  2021年   159篇
  2020年   99篇
  2019年   125篇
  2018年   122篇
  2017年   68篇
  2016年   117篇
  2015年   109篇
  2014年   136篇
  2013年   175篇
  2012年   262篇
  2011年   210篇
  2010年   123篇
  2009年   92篇
  2008年   143篇
  2007年   137篇
  2006年   110篇
  2005年   112篇
  2004年   89篇
  2003年   77篇
  2002年   70篇
  2001年   14篇
  2000年   3篇
  1999年   8篇
  1998年   15篇
  1997年   5篇
  1996年   2篇
  1995年   4篇
  1994年   11篇
  1993年   6篇
  1992年   10篇
  1991年   7篇
  1990年   8篇
  1989年   2篇
  1988年   6篇
  1987年   6篇
  1986年   5篇
  1985年   5篇
  1983年   2篇
  1982年   4篇
  1981年   2篇
  1979年   3篇
  1978年   3篇
  1977年   2篇
  1974年   5篇
  1973年   1篇
  1971年   1篇
  1965年   1篇
排序方式: 共有2800条查询结果,搜索用时 828 毫秒
51.
52.
Vitamin D deficiency is prevalent in the pediatric CKD population. Recognizing that renal transplant recipients have CKD, we assessed the prevalence of vitamin D insufficiency and deficiency in pediatric renal transplant recipients, compared to a healthy pediatric population. We prospectively studied 25(OH)D levels in 29 pediatric renal transplant recipients and 45 control patients over one yr. The overall prevalence of vitamin D insufficiency and deficiency was common in both populations, at 76% (95% CI: 61, 87%) in the pediatric renal transplant recipients and 91% (95% CI: 80, 98%) in the control group. In the paired renal transplant samples, the mean 25(OH)D level was 52.3 ± 17.9 nmol/L in the winter and 65.6 ± 18.8 nmol/L in the summer (95% CI diff.: 3.9, 22.7), in keeping with a significant seasonal difference. The mean dietary intake of vitamin D in the renal transplant recipients, assessed by three‐day dietary record, was 5.7 μg/day, with a vitamin D intake below the EAR in the majority. We did not find an association between vitamin D intake and 25(OH)D levels in this study, likely due to the low dietary intake of vitamin D within the transplant population, identifying a potential area for intervention and improvement.  相似文献   
53.
A 9‐year‐old girl developed influenza A H1N1 pdm09‐associated myocarditis and pericarditis 2 days after starting zanamivir therapy. The virus was detected in the respiratory tract but not in the serum or pericardial effusion. The virus sampled from the respiratory tract had normal susceptibility to neuraminidase inhibitors. Although no differences in interferon‐γ, interleukin (IL)‐1β, and tumor necrosis factor‐α were observed between the plasma and pericardial effusion, some inflammatory cytokines or chemokines (IL‐6 and IL‐8) and vascular endothelial growth factor were remarkably elevated in the pericardial effusion compared with the plasma. This suggested that the influenza virus, after infecting the respiratory tract, affected the myocardium, causing myocarditis to gradually develop, which might have been followed by an autoreactive pericarditis causing increased pericardial effusion. Therefore, influenza‐associated myocarditis should be considered when influenza patients have respiratory and cardiac involvement, even during treatment with a neuraminidase inhibitor.  相似文献   
54.
Kim E  Sohn S  Lee M  Park C  Jung J  Park S 《Pituitary》2005,8(2):155-162
Growth hormone releasing hormone (GHRH) signals via G protein-coupled receptors (GHRH-R) to enhance intracellular Gαs/adenylyl cyclase/cAMP signaling, which in turn has positive effects on GH synthesis and release, as well as proliferation of the GH-producing cells of the anterior pituitary gland. Some GH-producing pituitary tumors express a constitutively active mutant form of Gαs (gsp oncogene). It has been reported that these tumors are more responsive to octreotide therapy. In this study we used a rat GH-producing cell line (GH3) stably transfected with the human GHRH-R cDNA (GH3-GHRHR cells) as a model to study the effects of gsp oncogene on somatostatin (SRIH) receptor subtype 1 and 2 (sst1 and sst2) mRNA levels. Transient transfection of gsp oncogene in GH3-GHRHR cells for 48 h increased intracellular cAMP levels and GH release. Phosphodiesterase (PDE) 4, sst1 and sst2 mRNA levels were increased by G protein mutation as assessed by real-time RT-PCR. Increased PDE mRNA levels in gsp-transfected cells may be a compensatory mechanism to the constitutive activation of cAMP-dependent pathway by G protein mutation and is consistent with reports of higher PDE expression in human pituitary tumor that express gsp. Our data suggest that higher expression of sst1 and sst2 mRNA induced by the gsp oncogene may be a mechanism by which gsp-positive tumors show a greater response to SRIH. GH3 cells permanently transfected with GHRH-R can be used for in vitro studies of actions of GHRH.  相似文献   
55.
Our previous study suggested that fenofibrate affects obesity and lipid metabolism in a sexually dimorphic manner in part through the differential activation of hepatic peroxisome proliferator-activated receptor alpha (PPARalpha) in male and female C57BL/6J mice. To determine whether fenofibrate reduces body weight gain and adiposity in female sham-operated (Sham) and ovariectomized (OVX) C57BL/6J mice, the effects of fenofibrate on not only body weight, white adipose tissue (WAT) mass, and food intake, but also the expression of both leptin and PPARalpha target genes were measured. Compared to their respective low-fat diet-fed controls, both Sham and OVX mice exhibited increases in body weight and WAT mass when fed a high-fat diet. Fenofibrate treatment decreased body weight gain and WAT mass in OVX, but not in Sham mice. Furthermore, fenofibrate increased the mRNA levels of PPARalpha target genes encoding peroxisomal enzymes involved in fatty acid beta-oxidation, and reduced apolipoprotein C-III (apo C-III) mRNA, all of which were expressed at higher levels in OVX compared to Sham mice. However, leptin mRNA levels were found to positively correlate with WAT mass, and food intake was not changed in either OVX or Sham mice following fenofibrate treatment. These results suggest that fenofibrate differentially regulates body weight and adiposity due in part to differences in PPARalpha activation, but not to differences in leptin production, between female OVX and Sham mice.  相似文献   
56.
To promote bone marrow donation, both the safety and well-being of healthy unrelated volunteer donors must be protected. This prospective cohort study evaluated donors' health-related quality of life (HRQOL) and identified factors associated with it. Using the Medical Outcomes Study Short Form 36 Health Survey (SF-36) before bone marrow harvesting (BMH), and again 1 week and 3 months after the donors' discharge, we evaluated HRQOL of 565 donors (329 men, 236 women) registered with the Japan Marrow Donor Program (JMDP). We also examined the data routinely collected by the JMDP, such as BMH-related problems and other demographic and medical variables, to determine whether such data could be used to predict donors' HRQOL after discharge. Mean scores of all pre-BMH SF-36 subscales showed better functioning than the national norm. One week after discharge, mean scores on physical functioning (PF) and role-physical (RP) subscales, indicative of physical states, and bodily pain (BP) were approximately 1 SD lower than the national norm; however, mental health (MH) and general health perception (GH) remained above normal; the most frequent BMH-related problems were pain at the donation site and lower back pain, which were associated with lower PF, RP, and BP scores. Female gender and duration of procedure predicted lower PF, RP, and BP. Three months after discharge, mean scores of all SF-36 subscales had returned to baseline levels. These data show that the adverse effects of BMH on donors' HRQOL are transient and can be minimized by better management of pain.  相似文献   
57.
Particulate matter (PM) is becoming an increasing health concern and there is a need to develop detection methods to keep its harmful effects in check. Generation of reactive oxygen species (ROS) by PM is often associated with metal compounds, hence our aim is to screen for a peptide probe towards improved collection and the detection of PM having a high metal content. Peptides are putative recognition molecules due to their versatility and ease of modification to enhance their binding selectivities. PM binding peptides were screened using the peptide array and different binding behaviors in terms of different spot colors (yellow, mixed and gray), indicating the different composition of bound PMs, were observed. The strongest binding peptides were identified as follows: NHVNTNYYPTLH (gray), NGYYPHSHSYHQ (mixed) and HHLHWPHHHSYT (yellow), with relative binding ratios of 125%, 144% and 136%, in comparison with WQDFGAVRSTRS, a peptide screened from a phage display in our previous study. Inductively coupled plasma mass spectrometry (ICPMS) analyses revealed that Co, Ni and Zn content in the PM bound to the HHLHWPHHHSYT peptide spot were respectively 12.5, 15.8 and 7.8 times that of the PM bound to no peptide spot, suggesting this peptide probe is applicable to collect PM with a high metal content.

Using peptide array, peptides binding to particulate matter with high metal content were screened and characterized by focusing on the different spot colors (yellow, mixed and gray).  相似文献   
58.
59.
60.
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