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   211870篇
  免费   16842篇
  国内免费   6323篇
耳鼻咽喉   1911篇
儿科学   6166篇
妇产科学   3363篇
基础医学   35203篇
口腔科学   3261篇
临床医学   18544篇
内科学   37948篇
皮肤病学   3136篇
神经病学   10833篇
特种医学   4096篇
外国民族医学   19篇
外科学   16666篇
综合类   26492篇
现状与发展   32篇
一般理论   3篇
预防医学   26628篇
眼科学   1997篇
药学   20899篇
  100篇
中国医学   7582篇
肿瘤学   10156篇
  2023年   3244篇
  2022年   4699篇
  2021年   9018篇
  2020年   8012篇
  2019年   8186篇
  2018年   8125篇
  2017年   7386篇
  2016年   7379篇
  2015年   8024篇
  2014年   13019篇
  2013年   13899篇
  2012年   12620篇
  2011年   14320篇
  2010年   11430篇
  2009年   10024篇
  2008年   9645篇
  2007年   9499篇
  2006年   8510篇
  2005年   7476篇
  2004年   6481篇
  2003年   5735篇
  2002年   4286篇
  2001年   4110篇
  2000年   3473篇
  1999年   3140篇
  1998年   2666篇
  1997年   2561篇
  1996年   2263篇
  1995年   2196篇
  1994年   1976篇
  1993年   1641篇
  1992年   1396篇
  1991年   1258篇
  1990年   1094篇
  1989年   976篇
  1988年   858篇
  1987年   719篇
  1986年   608篇
  1985年   1556篇
  1984年   1671篇
  1983年   1198篇
  1982年   1248篇
  1981年   1121篇
  1980年   1034篇
  1979年   929篇
  1978年   757篇
  1977年   621篇
  1976年   770篇
  1975年   589篇
  1974年   557篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Background: Dense deposit disease and atypical hemolytic uremic syndrome are often caused by Complement Factor H (CFH) mutations. This study describes the retinal abnormalities in dense deposit disease and, for the first time, atypical haemolytic uremic syndrome. It also reviews our understanding of drusen pathogenesis and their relevance for glomerular disease. Methods: Six individuals with dense deposit disease and one with atypical haemolytic uremic syndrome were studied from 2 to 40 years after presentation. Five had renal transplants. All four who had genetic testing had CFH mutations. Individuals underwent ophthalmological review and retinal photography, and in some cases, optical coherence tomography, and further tests of retinal function. Results: All subjects with dense deposit disease had impaired night vision and retinal drusen or whitish-yellow deposits. Retinal atrophy, pigmentation, and hemorrhage were common. In late disease, peripheral vision was restricted, central vision was distorted, and there were scotoma from sub-retinal choroidal neovascular membranes and atypical serous retinopathy. Drusen were present but less prominent in the young person with atypical uremic syndrome due to a heterozygous CFH mutation. Conclusions: Drusen are common in forms of C3 glomerulopathy caused by compound heterozygous or heterozygous CFH mutations. They are useful diagnostically but also impair vision. Drusen have an identical composition to glomerular deposits. They are also identical to the drusen of age-related macular degeneration, and may respond to the same treatments. Individuals with a C3 glomerulopathy should be assessed ophthalmologically at diagnosis, and monitored regularly for vision-threatening complications.  相似文献   
82.
In the USA, the Black Church is among the most important institutions in the Black community, offering numerous spiritual, social and health benefits. Yet, the presence of homonegativity in many Black Churches may mitigate those effects for gay Black youth. This research examines the role of the Church in the lives of gay and bisexual Black youth to understand how they reconcile any tension between their religious and sexual identities. Through interviews with pastors of Black churches (n = 21) and young Black men who have sex with men (n = 30), we explored homonegativity and young men’s experiences within the Black Church. Findings reveal that despite the prevalence of homonegativity within Black churches, religious involvement remains important for young men and many remain involved in non-affirming churches. The importance of the Church for young men stems from their significant involvement as youth and the integration of religion, family and community. Young men may not be able to leave their religious homes as readily as other gay youth given the cultural relevance of the Church. As a result, young men made attempts to conceal their sexuality in church to avoid shame and gossip and find opportunities to balance their sexuality and religiosity.  相似文献   
83.
This prospective cohort study was conducted to compare the accuracy of QuantiFERON®-TB (QFT) Gold In-Tube test and tuberculin skin test (TST) in diagnosing tuberculosis (TB) in predominantly bacille Calmette–Guerin-vaccinated children with a high incidence of malnutrition. The sensitivity of the QFT versus the TST was 69.6% versus 52.9% for WHO-defined TB, with specificity of 86% versus 78.3%, respectively. The concordance of the TST and QFT was 79% overall (κ = 0.430), 62.5% in those with WHO-defined TB and 85.7% in those without TB. Majority of the QFT+/TST − discordance was seen in children with TB, whereas majority of the TST+/QFT − discordance was seen in those without TB. The TST was more likely to be negative in children with moderate-to-severe malnutrition (P = 0.003) compared to the QFT, which was more likely to be positive in younger children. The significantly better performance of the QFT in malnourished children and those at younger ages supports its use for TB diagnosis in these subpopulations.  相似文献   
84.
Ovarian carcinoma is one of the most lethal malignancies, but only very few prognostic biomarkers are known. The degradome, comprising proteases, protease non-proteolytic homologues and inhibitors, have been involved in the prognosis of many cancer types, including ovarian carcinoma. The prognostic significance of the whole degradome family has not been specifically studied in high-grade serous ovarian cancer. A targeted DNA microarray known as the CLIP-CHIP microarray was used to identify potential prognostic factors in ten high-grade serous ovarian cancer women who had early recurrence (<1.6 years) or late/no recurrence after first line surgery and chemotherapy. In women with early recurrence, we identified seven upregulated genes (TMPRSS4, MASP1/3, SPC18, PSMB1, IGFBP2, CFI – encoding Complement Factor I – and MMP9) and one down-regulated gene (ADAM-10). Using immunohistochemistry, we evaluated the prognostic effect of these 8 candidate genes in an independent cohort of 112 high-grade serous ovarian cancer women. Outcomes were progression, defined according to CA-125 criteria, and death. Multivariate Cox proportional hazard regression models were done to estimate the associations between each protein and each outcome. High ADAM-10 expression (intensity of 2–3) was associated with a lower risk of progression (adjusted hazard ratio (HR): 0.51; 95% confidence interval (CI): 0.29-0.87). High complement factor I expression (intensity 2–3) was associated with a higher risk of progression (adjusted HR: 2.30, 95% CI: 1.17–4.53) and death (adjusted HR: 3.42; 95% CI: 1.72–6.79). Overall, we identified the prognostic value of two proteases, ADAM-10 and complement factor I, for high-grade serous ovarian cancer which could have clinical significance.  相似文献   
85.
《Vaccine》2019,37(35):5059-5066
Background: Hepatitis B virus (HBV) infection is highly endemic in most low income countries including Cambodia. This nationwide serosurvey was conducted to assess the impact of hepatitis B vaccination and to determine whether Cambodia met the WHO regional 2017 target of hepatitis B surface antigen (HBsAg) seroprevalence less than 1% in five-year-old children.Methods: A cross-sectional multi-stage cluster survey was conducted among children born during 2010–2012 and their mothers in Cambodia. HBsAg prevalence was estimated by rapid point-of-care testing, and demographic data, including vaccination history, was collected. Vaccine coverage in children and the prevalence of HBsAg among children and mothers was calculated taking into account the complex survey design. Factors associated with children’s failure to receive timely (within 24 h) vaccination were analysed by multivariate logistic analysis.Findings: A total of 2,520 children 5–7 years old and 2,028 mothers were recruited. In total, 78.4% of children received hepatitis B vaccination birth-dose (HepB-BD); of these, 58.7% were administered ≤ 24 h. Birth at home or “other” location were independent risk factors for children’s failure to receive timely HepB-BD. Overall HBsAg seroprevalence was 4.39% (95%CI: 3.53%–5.45%) among mothers and 0.56% (95%CI: 0.32%–0.98%) among children. The prevalence among children without hepatitis B vaccination was 4.62% (95%CI: 1.31%–14.97%). Among children with a HBsAg-positive mother, prevalence was 10.11% (95%CI: 5.41%–18.11%).Interpretation: Having achieved the 2017 target of less than 1% HBsAg prevalence among 5 years old children, Cambodia can now focus on eliminating mother-to-child transmission of HBV. Moreover, the high HBsAg prevalence among mothers suggests that routine screening with proper linkage to care and treatment is needed. Strengthening measures to improve vaccination coverage further and eliminate mother-to-child transmission by coordinated programming with other services offering additional HBV interventions will help move towards the global goal of hepatitis B elimination by 2030.Funding: As per sources of funding.  相似文献   
86.
miR-30c has been acknowledged as a tumor suppressor in various human cancers, such as ovarian cancer, gastric cancer, and prostate cancer. However, the role of miR-30c in glioblastoma (GBM) needs to be investigated. In our study, we found that the expression of miR-30c was significantly downregulated in GBM tissues and cell lines. We found that overexpression of miR-30c inhibited cellular proliferation of GBM cells in vitro and in vivo. More GBM cells were arrested in the G0 phase after miR-30c overexpression. Moreover, we showed that miR-30c overexpression suppressed the migration and invasion of GBM cells. Mechanistically, we found that SOX9 was a direct target of miR-30c in GBM cells. Overexpression of miR-30c inhibited the mRNA and protein levels of SOX9 in GBM cells. Moreover, there was a negative correlation between the expression of miR-30c and SOX9 in GBM tissues. Finally, we showed that restoration of SOX9 in GBM cells reversed the proliferation, migration, and invasion of GBM cells transfected with miR-30c mimic. Collectively, our results demonstrated that miR-30c suppressed the proliferation, migration, and invasion of GBM cells via targeting SOX9.  相似文献   
87.
《Vaccine》2021,39(45):6601-6613
AKS-452 is a biologically-engineered vaccine comprising an Fc fusion protein of the SARS-CoV-2 viral spike protein receptor binding domain antigen (Ag) and human IgG1 Fc (SP/RBD-Fc) in clinical development for the induction and augmentation of neutralizing IgG titers against SARS-CoV-2 viral infection to address the COVID-19 pandemic. The Fc moiety is designed to enhance immunogenicity by increasing uptake via Fc-receptors (FcγR) on Ag-presenting cells (APCs) and prolonging exposure due to neonatal Fc receptor (FcRn) recycling. AKS-452 induced approximately 20-fold greater neutralizing IgG titers in mice relative to those induced by SP/RBD without the Fc moiety and induced comparable long-term neutralizing titers with a single dose vs. two doses. To further enhance immunogenicity, AKS-452 was evaluated in formulations containing a panel of adjuvants in which the water-in-oil adjuvant, Montanide™ ISA 720, enhanced neutralizing IgG titers by approximately 7-fold after one and two doses in mice, including the neutralization of live SARS-CoV-2 virus infection of VERO-E6 cells. Furthermore, ISA 720-adjuvanted AKS-452 was immunogenic in rabbits and non-human primates (NHPs) and protected from infection and clinical symptoms with live SARS-CoV-2 virus in NHPs (USA-WA1/2020 viral strain) and the K18 human ACE2-trangenic (K18-huACE2-Tg) mouse (South African B.1.351 viral variant). These preclinical studies support the initiation of Phase I clinical studies with adjuvanted AKS-452 with the expectation that this room-temperature stable, Fc-fusion subunit vaccine can be rapidly and inexpensively manufactured to provide billions of doses per year especially in regions where the cold-chain is difficult to maintain.  相似文献   
88.
《Drug discovery today》2022,27(6):1733-1742
Compounds that exhibit assay interference or undesirable mechanisms of bioactivity are routinely encountered in assays at various stages of drug discovery. We observed that assays for the investigation of thiol-reactive and redox-active compounds have not been collected in a comprehensive review. Here, we review these assays and subject them to experimental optimization to improve their reliability. We demonstrate the usefulness of our assay cascade by assaying a library of bioactive compounds, chemical probes, and a set of approved drugs. These high-throughput assays should complement the array of wet-lab and in silico assays during the initial stages of hit discovery campaigns to pursue only hit compounds with tractable mechanisms of action.  相似文献   
89.
ObjectivesTo review the evidence pertaining to the association between cow’s milk protein allergy and recurrent acute otitis media and otitis media with effusion.MethodsThe CENTRAL, Web of Science, EMBASE, MEDLINE, LILACS databases, and gray literature were searched.ResultsFour studies were included, identifying the prevalence rates: 0.2% of delayed speech due to chronic otitis media with effusion in 382 children with cow’s milk protein allergy, 10.7% of cow’s milk protein allergy in 242 children who underwent ENT procedures, 40% of cow’s milk protein allergy in 25 children with recurrent otitis media with effusion and higher tendency to otitis media in children with cow’s milk protein allergy of 186 children (1.5 + 0.6 vs. 0.4 + 0.1; p < 0.1).ConclusionConsidering the characteristics and methodological variations of the identified studies, it is not possible to state that there is reliable evidence of an association between cow’s milk protein allergy and otitis media.  相似文献   
90.
《Vaccine》2019,37(47):6987-6995
Vero cells are nowadays widely used in the production of human vaccines. They are considered as one of the most productive and flexible continuous cell lines available for vaccine manufacturing. However, these cells are anchorage dependent, which greatly complicates upstream processing and process scale-up. Moreover, there is a recognized need to reduce the costs of vaccine manufacturing to develop vaccines that are affordable worldwide. The use of cell lines adapted to suspension growth contributes to reach this objective.The current work describes the adaptation of Vero cells to suspension culture in different serum free media according to multiple protocols based on subsequent passages. The best one that relies on cell adaption to IPT-AFM an in-house developed animal component free medium was then chosen for further studies. Besides, as aggregates have been observed, the improvement of IPT-AFM composition and mechanical dissociation were also investigated.In addition to IPT-AFM, three chemically defined media (CD293, Hycell CHO and CD-U5) and two serum free media (293SFMII and SFM4CHO) were tested to set up a serum free culture of the suspension-adapted Vero cells (VeroS) in shake flasks. Cell density levels higher than 2 × 106 cells/mL were obtained in the assessed conditions. The results were comparable to those obtained in spinner culture of adherent Vero cells grown on Cytodex 1 microcarriers.Cell infection with LP-2061 rabies virus strain at an MOI (Multiplicity of Infection) of 0.1 and a cell density of 8 ± 0.5 × 105 cells/mL resulted in a virus titer higher than 107 FFU/mL in all media tested. Nevertheless, the highest titer equal to 5.2 ± 0.5 × 107 FFU/mL, was achieved in IPT-AFM containing a reduced amount of Ca++ and Mg++. Our results demonstrate the suitability of the obtained VeroS cells to produce rabies virus at a high titer, and pave the way to develop VeroS cells bioreactor process for rabies vaccine production.  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