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   10523篇
  免费   604篇
  国内免费   43篇
耳鼻咽喉   102篇
儿科学   241篇
妇产科学   261篇
基础医学   1469篇
口腔科学   216篇
临床医学   1033篇
内科学   2349篇
皮肤病学   133篇
神经病学   927篇
特种医学   319篇
外国民族医学   1篇
外科学   1481篇
综合类   135篇
一般理论   14篇
预防医学   809篇
眼科学   208篇
药学   753篇
中国医学   6篇
肿瘤学   713篇
  2023年   66篇
  2022年   106篇
  2021年   212篇
  2020年   155篇
  2019年   188篇
  2018年   202篇
  2017年   168篇
  2016年   156篇
  2015年   242篇
  2014年   307篇
  2013年   482篇
  2012年   751篇
  2011年   794篇
  2010年   421篇
  2009年   363篇
  2008年   662篇
  2007年   729篇
  2006年   693篇
  2005年   664篇
  2004年   654篇
  2003年   574篇
  2002年   613篇
  2001年   144篇
  2000年   123篇
  1999年   155篇
  1998年   128篇
  1997年   107篇
  1996年   104篇
  1995年   95篇
  1994年   74篇
  1993年   75篇
  1992年   78篇
  1991年   82篇
  1990年   66篇
  1989年   55篇
  1988年   51篇
  1987年   42篇
  1986年   48篇
  1985年   44篇
  1984年   42篇
  1983年   35篇
  1982年   62篇
  1981年   29篇
  1980年   28篇
  1979年   34篇
  1978年   28篇
  1977年   32篇
  1975年   29篇
  1974年   17篇
  1973年   22篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Increasing sugar-sweetened beverages (SSB) consumption and associated health impacts warrant health-policy action. We assessed associations of socioeconomic and lifestyle variables with adolescents’ consumption of regular soda (RSD), sport (SD), and energy (ED) drinks. Cross-sectional study of 3930 Spanish adolescents (2089 girls, 1841 boys) aged 13–18 years). We compared frequency of consuming each SSB type (European Food Safety Authority questionnaire) with sociodemographic and lifestyle variables (standardized questions). RSD, SD, and ED were consumed at least weekly by 72.7%, 32.3%, and 12.3% of participants, respectively, and more frequently (p < 0.001) by boys, compared to girls. Multivariate ordinal logistic regression showed inverse association between RSD, SD, and ED consumption and parental occupation-based socioeconomic status (p < 0.01). Daily smoking was associated (p < 0.001) with higher ED (OR 3.64, 95% CI 2.39–5.55) and RSD (OR 2.15, 95% CI 1.56–2.97) consumptions. SD intake was associated inversely with smoking (OR 0.60, 95% CI 0.40–0.89, p = 0.012) and directly with physical activity (OR 2.93, 95% CI 2.18–3.95, p < 0.001). School performance was lower among ED (OR 2.14, 95% CI, 1.37–3.35, p = 0.001) and RSD (OR 1.81, 95% CI 1.24–2.64, p = 0.002) consumers, compared to SD. Maleness and low socioeconomic status predicted SSB consumption. Smoking and low school performance were associated with higher ED and RSD intakes.  相似文献   
102.
The European Journal of Health Economics - Economic cost estimates have the potential to provide a valuable alternative perspective on the COVID-19 burden. We estimate the premature mortality...  相似文献   
103.
Purpose: Injuries are one of the leading causes of death and lead to a high social and financial burden. Injury patterns can vary significantly among different age groups and body regions. This study aimed to evaluate the relationship between mechanism of injury, patient comorbidities and severity of injuries. Methods: The study included trauma patients from July 2016 to June 2018, who were admitted to Sina Hospital, Tehran, Iran. The inclusion criteria were all injured patients who had at least one of the following: hospital length of stay more than 24 h, death in hospital, and transfer from the intensive care unit of another hospital. Data collection was performed using the National Trauma Registry of Iran minimum dataset. Results: The most common injury mechanism was road traffic injuries (49.0%), followed by falls (25.5%). The mean age of those who fell was significantly higher in comparison with other mechanisms (p < 0.001). Severe extremity injuries occurred more often in the fall group than in the vehicle collision group (69.0% vs. 43.5%, p < 0.001). Moreover, cases of severe multiple trauma were higher amongst vehicle collisions than injuries caused by falls (27.8% vs. 12.9%, p = 0.003). Conclusion: Comparing falls with motor vehicle collisions, patients who fell were older and sustained more extremity injuries. Patients injured by motor vehicle collision were more likely to have sustained multiple trauma than those presenting with falls. Recognition of the relationship between mechanisms and consequences of injuries may lead to more effective interventions.  相似文献   
104.
Culture of epithelial cells derived from the oviduct of different species   总被引:8,自引:2,他引:8  
This study proposes a procedure for the isolation and cultureof oviduct epithelial cells of several species. In-vitro cultureon such a feeder seems to allow full embryonic development andviability. The inner linings of Fallopian tubes from mouse,rabbit, cow and human were trypsinized and the epithelial cellswere enriched with Percoll gradient. Isolated cells, obtainedin high yield with good viability, were maintained in monolayerculture in B2-Menezo medium supplemented with serum, which alsosupports early embryonic development in vitro. The plated primarycultures reached confluence within 8 days, producting a monolayerof cohesive polygonalcells. Associated with this large epithelialcall population, ciliated cells as wellas polykaryotic cellsand few fibroblastic nestswere observed. After the first sub-culture,the ciliated cells disappeared and the epithelial cell monolayergrew rapidly to confluence with in 3 days and displayed contactinhibition. No epithelial cell growth could be obtained inculturein the absence of serum. The addition of oestrogens had no effecton any of the cultured oviductal epithelial cells. A sponotaneousalteration was observed in morphology and growth after severalpassages, the number of which depends mainly upon the species  相似文献   
105.
Three patients admitted to the surgical wards of Johannesburg Hospital in whom abdominal tuberculosis was suspected are presented. In every case difficulties were encountered in diagnosis and treatment. Each case presentation is followed by a short commentary on relevant aspects of abdominal tuberculosis.  相似文献   
106.
Heightened awareness by health care funders of the need to find more efficient ways of using scarce health care resources has led to greater demand for evidence of cost-effectiveness. Implicit in this demand is that evidence is generated using clear reporting and accepted methods. The research reported here updates an earlier review of published cost-utility analyses (CUAs) to address whether previously identified gaps in reporting have diminished over time. Raising CUA standards requires systematic and regular reviews of published material to allow adequate monitoring and evaluation. There is also a need to 'appraise the appraisers' in the sense of reviewing peer-review processes. This is particularly so in those journals which are growing in importance as outlets for economic evaluation information. The findings from this study indicate continuing variation in the quality of reporting. At the lower end of this spectrum improvements could be made in the reporting of comparators, in the clarity of effectiveness evidence, in the assignment of utility weights to health states and in reporting of sensitivity analysis. CUAs published in peer-reviewed specialist medical journals were more likely to be lower in quality suggesting guidance on the appraisal of economic submissions needs to be extended to the editors of these particular journals. These findings could be used to help to target attempts to raise the quality of evidence-based CUA information.  相似文献   
107.
We studied the potential of both stereoisomers of 17-[123I]iodovinyloestradiol (E- andZ-[123I]IVE) and of 11-methoxy-17-[123I]iodovinyloestradiol (E-andZ-[123I]MIVE) as suitable radioligands for the imaging of oestrogen receptor(ER)-positive human breast tumours. The 17-[123I]iodovinyloestradiols were prepared stereospecifically by oxidative radio-iododestannylation of the corresponding 17-tri-n-butylstannylvi-nyloestradiol precursors. Competitive binding studies were performed in order to determine the relative binding affinity (RBA) of the unlabelled 17-iodovinyloes-tradiols for the ER in both human MCF-7 breast tumour cells and rat uterine tissue, compared with that of diethylstilboestrol (DES). Target tissue uptake, retention and uptake selectivity of their123I-labelled analogues were studied in immature female rats. All four 17-iodovi-nyloestradiols showed high affinity for the ER in human MCF-7 cells, as well as rat uterus. Their RBA for the ER showed the following order of decreasing potency: RBA of DES >Z-IVE >Z-MIVE >E-MIVE E-IVE. Neither of these 17-iodovinyloestradiols showed any significant binding to the sex hormone binding globulin in human plasma. The biodistribution studies showed ER-mediated uptake in the uterus, ovaries and pituitary, that ofE- andZ-[123I]MIVE being higher than that ofE- andZ-[123I]IVE. High target-to-non-target tissue uptake ratios, especially at longer periods after injection (up to 24 h), were exhibited by both isomers of [123I]MIVE. The uterus-to-blood uptake ratio was higher forE-[123I]MIVE. However, the uterus-to-fat uptake ratio appeared to be higher for theZ-isomer of [123I]MIVE, especially at 24 h after injection. Metabolic properties and temperature effects, which play a more important role in vivo, probably cause the discrepancies seen between in vitro and in vivo binding results. On the basis of their in vitro binding properties and in vivo distribution characteristics we conclude thatE- andZ-[123I]MIVE could be suitable radioligands for the diagnostic imaging of ER in human breast cancer. Therefore, further studies with these radioligands in mature normal and tumour-bearing rats are warranted.  相似文献   
108.
Background: The anticancer role of tumor necrosis factor-alpha (TNF-) has been limited by toxicity. These experiments evaluate blocking endogenous interferon-gamma (IFN-) activity to abrogate TNF- toxicity. Methods: C57Bl/6 mice bearing MCA 105 tumor were treated with TNF- and anti-IFN- antibody (Ab) to evaluate the effect on the acute lethality of TNF- and their efficacy as evaluated by tumor growth rate, tumor histology, and survival. Results: Anti-IFN- Ab decreased TNF- lethality. Anti-IFN- Ab alone increased tumor growth significantly more than did nonimmune IgG (p2<0.0001). Tumor-bearing mice that received nonimmune IgG and TNF- had slower tumor growth (p2<0.02) and a trend toward improved survival (p=0.07) compared with saline-treated controls. Anti-IFN- Ab abrogated the antitumor effect of TNF-, prevented acute tumor necrosis histologically, and resulted in tumor growth rate and host survival similar to that of controls. The findings in mice that received anti-IFN- Ab and high-dose TNF- were comparable with those in mice that received a lower, equitoxic dose of TNF- alone. Conclusions: Blocking endogenous IFN- accelerates tumor growth in this model and partially abrogates the toxic and antitumor activity of exogenous TNF- equally. This suggests that blocking endogenous IFN- activity is not a useful strategy for limiting TNF- treatment toxicity.Presented in part at the 45th Annual Cancer Symposium of The Society of Surgical Oncology, New York, New York, March 15–18, 1992.  相似文献   
109.
110.
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