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   2354篇
  免费   120篇
  国内免费   7篇
耳鼻咽喉   20篇
儿科学   144篇
妇产科学   85篇
基础医学   284篇
口腔科学   42篇
临床医学   183篇
内科学   462篇
皮肤病学   34篇
神经病学   135篇
特种医学   80篇
外科学   229篇
综合类   39篇
预防医学   211篇
眼科学   219篇
药学   143篇
中国医学   8篇
肿瘤学   163篇
  2023年   4篇
  2022年   32篇
  2021年   63篇
  2020年   37篇
  2019年   55篇
  2018年   61篇
  2017年   42篇
  2016年   62篇
  2015年   65篇
  2014年   82篇
  2013年   104篇
  2012年   194篇
  2011年   226篇
  2010年   135篇
  2009年   104篇
  2008年   156篇
  2007年   165篇
  2006年   130篇
  2005年   133篇
  2004年   135篇
  2003年   102篇
  2002年   112篇
  2001年   19篇
  2000年   23篇
  1999年   22篇
  1998年   19篇
  1997年   16篇
  1996年   15篇
  1995年   6篇
  1994年   9篇
  1993年   10篇
  1992年   15篇
  1991年   12篇
  1990年   9篇
  1989年   10篇
  1988年   9篇
  1987年   8篇
  1986年   6篇
  1985年   7篇
  1984年   5篇
  1983年   4篇
  1982年   6篇
  1981年   7篇
  1980年   7篇
  1979年   8篇
  1978年   5篇
  1976年   5篇
  1974年   6篇
  1971年   3篇
  1962年   2篇
排序方式: 共有2481条查询结果,搜索用时 46 毫秒
141.
The aim of this study was to find the correlation between serum p53 and carcinoma of the bladder and to investigate whether serum p53 protein can be used as a tumor marker for p53 gene alteration. The study included patients with carcinoma of the bladder and controls. Serum p53 protein estimation was done with an ELISA kit. There were 23 patients with superficial and 17 with invasive carcinoma. The median serum p53 was 31.5 U/ml in superficial and 41 U/ml in invasive cancer. This was significantly higher than the mean value (16.4 U/ml) of controls. Serum p53 rises in patients with carcinoma of the bladder and correlates with the grade of the disease .It can therefore be used as a tumor marker for bladder cancer.  相似文献   
142.
Nutrition and low birth weight: from research to practice   总被引:1,自引:0,他引:1  
Low birth weight (LBW) remains a significant public health problem in many developing countries, and poor nutrition both before and during pregnancy is recognized as an important cause. Emerging evidence on the role of intergenerational effects in determining maternal preconceptual nutritional status indicates the need for continued investment in strategies that improve women's nutrition and health throughout the life cycle, especially during the early years. Controlled trials have shown that improving food intakes during pregnancy effectively reduces LBW, but programs have been less successful because these interventions are expensive and difficult to manage. Multivitamin-mineral supplements have been viewed as a simpler solution, but 2 of 3 controlled trials conducted to date failed to show that multivitamin-mineral supplements are more effective than are iron-folate supplements, which are already the standard of care during pregnancy. Emerging evidence indicating the benefits of iron supplements in improving birth weight illustrate the need for increased efforts to reduce iron deficiency by improving coverage of antenatal programs and promoting fortification. Other causes of LBW include environmental factors, such as smoking; indoor air pollution; and infections, such as malaria. However, little is known about the interactions between nutrition and infection. Underlying social factors, such as poverty and women's status, are also important, especially in South Asia, where more than one-half of the world's LBW infants are born. In summary, strategies that combine nutrition-based interventions, such as improving food intakes and micronutrient status, especially iron status, with approaches that improve women's status and reproductive health are needed to reduce LBW.  相似文献   
143.
Rapid assessment of fine needle aspiration smears has become popular. The goal is minimal time required and fastest turn around time for test results in breast aspirates. In the present study, fine needle aspiration smears from 100 cases of breast lump were stained by modified ultrafast Papanicolaou stain which consisted of the following changes from ultrafast Papanicolaou stain: (i) Use of Gill 's haematoxylin instead of Richard Allan haematoxylin, (ii) omission of orange G from cytostain. Wet fixed smears subjeted to May-Gruenwald and Giemsa stain and an air dried smear subjected to modified ultrafast Papanicolaou stain were compared. Smears stained by modified stain showed transparent cells with crisp nuclear features in a blood free background. Total time required in this staining was 130 seconds. Out of 100, diagnosis was inadequate in 5 cases. In 95 cases cytological diagnosis was as follows: 60 benign, 27 ductal malignancy and 8 of inflammatory lesions. There was 100% agreement in cytologic diagnosis offered on smears stained by May-Gruenwald and Giemsa and modified ultrafast Papanicolaou stain.  相似文献   
144.
The impact of iron-only supplements (FE) versus multiple micronutrient supplements containing iron (MM) during pregnancy on iron status was assessed in a subsample (n = 453) of women who participated in a randomized double-blind trial in Mexico. Compliance, monitored by observation, was high (>85%). The two groups were similar at recruitment (<13 wk gestation) for various sociodemographic characteristics and for mean hemoglobin (Hb) concentrations and prevalence of anemia (Hb < 110 g/L; 11%). However, mean serum ferritin was higher (P < 0.05) in the MM group (n = 142) compared to the FE group (n = 148) and the prevalence of iron deficiency (serum ferritin < 12 micro g/L) was lower in the MM group (44.4%) compared to the FE group (57.4%). By the third trimester, almost half the women were anemic in both groups, and mean Hb (g/L) was lower for the MM group (104.2; 95% CI: 102.5, 106.0) compared to the FE group (108.1; 95% CI: 106.4, 109.8) after adjusting for baseline serum ferritin. In contrast, there were no differences in Hb concentrations at 1 mo postpartum or in mean ferritin and prevalence of iron deficiency at 32 wk gestation and 1 mo postpartum (90.9 and 45.1% for the MM group; 92.6 and 47.3% for the FE group, respectively). In conclusion, rather than improve Hb or iron status relative to FE-only supplements as hypothesized, MM supplements may have slightly reduced Hb concentrations during pregnancy. Neither supplement was able to meet iron needs as evidenced by dramatic increases in anemia and iron deficiency by the end of pregnancy.  相似文献   
145.
We previously reported that inhaled isobutyl nitrite inhibited macrophage tumoricidal activity by inhibiting inducible nitric oxide (NO) production. In the present study, a much shorter inhalant exposure regimen (five daily exposures) inhibited inducible NO and the NO synthase (NOS2). One of the ways in which NO and NOS2 are regulated is by ubiquitin-dependent NOS2 degradation. Immunoprecipitated NOS2 showed increased poly-ubiquitination, following exposure to the inhalant. In addition, Western blots of macrophage nuclear extracts for the NFkappaB subunit, p65, showed that exposure to the inhalant inhibited NFkappaB signaling, necessary for induction of NOS2. The inhalant blocked phosphorylation of the NFkappaB inhibitor, IkappaBalpha. The inhibition of NFkappaB signaling following inhalant exposure was confirmed using mice transgenic for the kappaB-dependent promoter of the HIV 5' LTR linked to luciferase. The data suggested that inhalant exposure likely inhibited macrophage NO production by blocking NFkappaB-mediated activation signaling and promoting poly ubiquitination of NOS2.  相似文献   
146.
Four xanthones were isolated from the roots of Andrographis paniculata using a combination of column and thin-layer chromatographic methods. They were characterized as (i) 1,8-di-hydroxy-3,7-dimethoxy-xanthone, (ii) 4,8-dihydroxy-2,7-dimethoxy-xanthone, (iii) 1,2-dihydroxy-6,8-dimethoxy-xanthone and (iv) 3,7,8-trimethoxy-1-hydroxy xanthone by IR, MS and NMR spectroscopic methods. In vitro study revealed that compound 1,2-dihydroxy-6,8-dimethoxy-xanthone possessed substantial anti-plasmodial activity against Plasmodium falciparum with its IC(50) value of 4 microg ml(-1). Xanthones bearing hydroxyl group at 2 position demonstrated most potent activity while xanthones with hydroxyl group at 1,4 or 8 position possessed very low activity. In vivo anti-malarial sensitivity test of this compound on Swiss Albino mice with Plasmodium berghei infection using Peters' 4-day test gave substantial reduction (62%) in parasitaemia after treating the mice with 30 mg kg(-1) dose. In vitro cytotoxicity against mammalian cells revealed that 1,2-dihydroxy-6,8-dimethoxy-xanthone is non-cytotoxic with its IC(50) > 32 microg ml(-1).  相似文献   
147.
The Plasmodium falciparum chloroquine resistance transporter (Pfcrt) K76T mutation and haplotype (amino acids 72-76) and the P. falciparum multidrug resistance 1 (Pfmdr1) mutation (N86Y) were analyzed as markers of chloroquine resistance in the DNAs of 73 blood samples from patients with P. falciparum malaria in India. Seventy of the 73 DNAs had the Pfcrt K76T mutation. Of these, 66 had the SVMNT haplotype and four had CVIET, the African/Southeast Asian haplotype. Only 20 of 69 DNAs had the Pfmdr1 N86Y mutation. It is surprising that the Pfcrt haplotype in India is predominantly SVMNT, rather than that seen in Southeast Asia. The widespread prevalence of the Pfcrt K76T mutation is a cause for concern.  相似文献   
148.
Persons with schizophrenia face elevated risk of infection with HIV. While HIV therapy is demanding, patients diagnosed with both conditions also require appropriate and consistent management of their psychiatric illness, for the same reasons that generally apply to persons with schizophrenia and because untreated psychiatric illness can interfere with full participation in HIV care. This study examines the correlates of use of and persistence on antipsychotic medications among HIV-infected individuals with schizophrenia, using merged New Jersey HIV/AIDS surveillance data and paid Medicaid claims. Persistence was defined as at least 2 months of medication use in a quarter. We identified 350 individuals who were dually diagnosed with HIV and schizophrenia. Overall, 81% of these beneficiaries had at least one claim for an antipsychotic medication at some point between 1992 and 1998. Multivariate techniques were used, including simple logistic regressions on use and robust longitudinal regressions that controlled for repeated observations on the same individual and treatment gaps. Among users of antipsychotic medications, persistence was very low at 37%. Racial/ethnic minorities were less likely to receive atypical antipsychotic medications. Use of atypical antipsychotics was associated with higher persistence. Our study confirmed past findings of racial disparities in the receipt of atypical antipsychotic medications. Findings suggest that use of atypical medications may benefit individuals dually diagnosed with HIV and serious mental illness.  相似文献   
149.
A patient with the typical features of neuroacanthocytosis is reported. Chorea, tics, personality changes and caudate atrophy on cranial MRI resulted in an erroneous diagnosis of Huntington's disease elsewhere. Attention to other features viz., absence of ocular motility disturbances, amyotrophy, areflexia, EMG evidence of axonopathy, raised serum creatinine phosphokinase (CPK) levels and the typical erythrocytic acanthocytosis enabled us to establish the correct diagnosis. The typical features of the disease as seen in the patient are discussed. In view of the implications for genetic counseling, careful clinical and laboratory evaluation is always warranted to exclude neuroacanthocytosis in all suspected cases of Huntington's disease.  相似文献   
150.
PURPOSE: This qualitative research aimed to elicit experiences and beliefs of recent South Asian immigrant women about their major health concerns after immigration. METHODS: Four focus groups were conducted with 24 Hindi-speaking women who had lived less than five years in Canada. The audiotaped data were transcribed, translated, and analyzed by identification of themes and subcategories. RESULTS: Mental health (MH) emerged as an overarching health concern with three major themes i.e. appraisal of the mental burden (extent and general susceptibility), stress-inducing factors, and coping strategies. Many participants agreed that MH did not become a concern to them until after immigration. Women discussed their compromised MH using verbal and symptomatic expressions. The stress-inducing factors identified by participants included loss of social support, economic uncertainties, downward social mobility, mechanistic lifestyle, barriers in accessing health services, and climatic and food changes. Women's major coping strategies included increased efforts to socialize, use of preventative health practices and self-awareness. CONCLUSION: Although participant women discussed a number of ways to deal with post-immigration stressors, the women's perceived compromised mental health reflects the inadequacy of their coping strategies and the available resources. Despite access to healthcare providers, women failed to identify healthcare encounters as opportunities to seek help and discuss their mental health concerns. Health and social care programs need to actively address the compromised mental health perceived by the studied group.  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