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   3572篇
  免费   370篇
  国内免费   31篇
耳鼻咽喉   43篇
儿科学   203篇
妇产科学   40篇
基础医学   406篇
口腔科学   133篇
临床医学   318篇
内科学   779篇
皮肤病学   128篇
神经病学   270篇
特种医学   313篇
外科学   620篇
综合类   64篇
预防医学   228篇
眼科学   67篇
药学   128篇
中国医学   4篇
肿瘤学   229篇
  2023年   23篇
  2022年   23篇
  2021年   48篇
  2020年   25篇
  2019年   41篇
  2018年   73篇
  2017年   79篇
  2016年   80篇
  2015年   105篇
  2014年   128篇
  2013年   181篇
  2012年   162篇
  2011年   112篇
  2010年   139篇
  2009年   131篇
  2008年   125篇
  2007年   128篇
  2006年   159篇
  2005年   131篇
  2004年   102篇
  2003年   99篇
  2002年   107篇
  2001年   80篇
  2000年   73篇
  1999年   77篇
  1998年   119篇
  1997年   101篇
  1996年   108篇
  1995年   72篇
  1994年   88篇
  1993年   58篇
  1992年   65篇
  1991年   71篇
  1990年   61篇
  1989年   80篇
  1988年   83篇
  1987年   60篇
  1986年   59篇
  1985年   55篇
  1984年   26篇
  1983年   34篇
  1982年   39篇
  1981年   30篇
  1980年   25篇
  1979年   35篇
  1978年   28篇
  1977年   22篇
  1976年   26篇
  1975年   21篇
  1967年   21篇
排序方式: 共有3973条查询结果,搜索用时 15 毫秒
991.
992.
We measured sporozoite- and total parasite antigen-specific IgG and IgM antibodies before and after treatment in matched groups of Gabonese children who presented with either mild or severe Plasmodium falciparum malaria. We investigated the influence of various parameters on these antibody responses, including clinical presentation, age, and post-treatment reinfection profiles. IgG but not IgM responses were strongly influenced by both clinical and parasitological status. IgG responses to the repeat region of the circumsporozoite protein, which were low at admission, particularly so in those with severe anemia, increased after treatment but showed no association with either age or reinfection profiles. Total parasite antigen-specific IgG responses were strongly influenced by parasitological status, and also differed significantly when segregated according to clinical status at admission, age, and reinfection histories. Most notably, anti-parasite IgG responses measured when children were parasite-free were higher and a good indicator of recent reinfections in those who presented with mild rather than with severe malaria. The profile of responses in the latter group suggests some immune system dysfunction, which may reflect the induction of tolerance to parasite antigens.  相似文献   
993.
The synthetic cytokine (Synthokine) SC-55494 is a high-affinity interleukin-3 (IL-3) receptor ligand that stimulates greater in vitro multilineage hematopoietic activity than native IL-3, while inducing no significant increase in inflammatory activity relative to native IL-3. The aim of this study was to investigate the in vivo hematopoietic response of rhesus monkeys receiving Synthokine after radiation-induced marrow aplasia. Administration schedule and dose of Synthokine were evaluated. All animals were total-body irradiated (TBI) with 700 cGy 60Co gamma radiation on day 0. Beginning on day 1, cohorts of animals (n = 5) received Synthokine subcutaneously (SC) twice daily with 25 micrograms/kg/d or 100 micrograms/kg/d for 23 days or 100 micrograms/kg/d for 14 days. Control animals (n = 9) received human serum albumin SC once daily at 15 micrograms/kg/d for 23 days. Complete blood counts were monitored for 60 days postirradiation and the durations of neutropenia (NEUT; absolute neutrophil count [ANC] < 500/microL) and thrombocytopenia (THROM; platelet count < 20,000/microL) were assessed. Synthokine significantly (P < .05) reduced the duration of THROM versus the HSA-treated animals regardless of dose or protocol length. The most striking reduction was obtained in the animals receiving 100 micrograms/kg/d for 23 days (THROM = 3.5 v 12.5 days in HSA control animals). Although the duration of NEUT was not significantly altered, the depth of the nadir was significantly lessened in all animal cohorts treated with Synthokine regardless of dose versus schedule length. Bone marrow progenitor cell cultures indicated a beneficial effect of Synthokine on the recovery of granulocyte-macrophage colony-forming units that was significantly higher at day 24 post-TBI in both cohorts treated at 25 and 100 micrograms/kg/d for 23 days relative to the control animals. Plasma pharmacokinetic parameters were evaluated in both normal and irradiated animals. Pharmacokinetic analysis performed in irradiated animals after 1 week of treatment suggests an effect of repetitive Synthokine schedule and/or TBI on distribution and/or elimination of Synthokine. These data show that the Synthokine, SC55 94, administered therapeutically post-TBI, significantly enhanced platelet recovery and modulated neutrophil nadir and may be clinically useful in the treatment of the myeloablated host.  相似文献   
994.
Autologous stem cell transplantation with or without in vitro lymphocyte depletion has been suggested as a new treatment option for severe autoimmune diseases. We describe five patients with autoimmune diseases (CREST syndrome, myasthenia gravis and Hashimoto's thyroiditis, systemic lupus erythematosus, atopic dermatitis, and rheumatoid arthritis) who underwent autologous bone marrow (n = 1) or peripheral blood progenitor cell (n = 4) transplantation with unmanipulated grafts as treatment for the autoimmune disease in one case or as treatment for a malignant disorder with a concomitant autoimmune disorder in four cases. In all patients serological and clinical signs of the autoimmune disease recurred early or persisted. These observations should be regarded as a cautionary note concerning the efficacy of high-dose therapy followed by transplantation of unmanipulated autologous stem cells for treatment of severe autoimmune diseases.  相似文献   
995.
996.
This study was designed to assess differences in drug and sex-related risk behaviors between injectors of opiates only, opiate/sedative mix only and stimulants only. Participants were current out-of-treatment injection drug users (IDUs), unaware of their HIV status, recruited through street outreach in Kiev, Odessa and Makeevka/Donetsk, Ukraine. Overall, 22% tested positive for HIV, including 39% among opiate/sedative injectors, 19% among opiate injectors and 17% among stimulant injectors. Despite these differences, stimulant injectors were at higher risk than other IDUs in sharing a used needle/syringe, always injecting with others, injecting a drug solution drawn from a common container, having an IDU sex partner, not using condoms during vaginal or anal sex and on composite measures of injection and sex risks. After controlling for age differences, stimulant injectors remained at higher risk in their needle and sex risk behaviors. Without intervention, it is likely that HIV will increase among stimulant injectors.  相似文献   
997.
998.
Nutrition is an important modifiable risk factor that plays a role in the strategy to prevent or delay the onset of dementia. Research on nutritional effects has until now mainly focused on the role of individual nutrients and bioactive components. However, the evidence for combined effects, such as multinutrient approaches, or a healthy dietary pattern, such as the Mediterranean diet, is growing. These approaches incorporate the complexity of the diet and possible interaction and synergy between nutrients. Over the past few years, dietary patterns have increasingly been investigated to better understand the link between diet, cognitive decline, and dementia. In this systematic review we provide an overview of the literature on human studies up to May 2014 that examined the role of dietary patterns (derived both a priori as well as a posteriori) in relation to cognitive decline or dementia. The results suggest that better adherence to a Mediterranean diet is associated with less cognitive decline, dementia, or Alzheimer disease, as shown by 4 of 6 cross-sectional studies, 6 of 12 longitudinal studies, 1 trial, and 3 meta-analyses. Other healthy dietary patterns, derived both a priori (e.g., Healthy Diet Indicator, Healthy Eating Index, and Program National Nutrition Santé guideline score) and a posteriori (e.g., factor analysis, cluster analysis, and reduced rank regression), were shown to be associated with reduced cognitive decline and/or a reduced risk of dementia as shown by all 6 cross-sectional studies and 6 of 8 longitudinal studies. More conclusive evidence is needed to reach more targeted and detailed guidelines to prevent or postpone cognitive decline.  相似文献   
999.
1000.
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