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   282103篇
  免费   59423篇
  国内免费   13736篇
耳鼻咽喉   3262篇
儿科学   6441篇
妇产科学   3217篇
基础医学   38709篇
口腔科学   8593篇
临床医学   39525篇
内科学   51441篇
皮肤病学   9636篇
神经病学   22831篇
特种医学   9416篇
外国民族医学   103篇
外科学   33450篇
综合类   36466篇
现状与发展   58篇
一般理论   43篇
预防医学   18962篇
眼科学   6501篇
药学   28636篇
  231篇
中国医学   14219篇
肿瘤学   23522篇
  2024年   851篇
  2023年   3357篇
  2022年   8741篇
  2021年   12119篇
  2020年   13046篇
  2019年   17212篇
  2018年   16910篇
  2017年   17838篇
  2016年   17953篇
  2015年   21300篇
  2014年   23387篇
  2013年   23170篇
  2012年   20601篇
  2011年   21634篇
  2010年   20237篇
  2009年   14192篇
  2008年   13742篇
  2007年   12188篇
  2006年   11649篇
  2005年   10961篇
  2004年   7391篇
  2003年   6920篇
  2002年   5860篇
  2001年   5072篇
  2000年   5043篇
  1999年   4533篇
  1998年   2522篇
  1997年   2558篇
  1996年   1928篇
  1995年   1877篇
  1994年   1633篇
  1993年   973篇
  1992年   1335篇
  1991年   1166篇
  1990年   941篇
  1989年   876篇
  1988年   794篇
  1987年   645篇
  1986年   494篇
  1985年   415篇
  1984年   199篇
  1983年   168篇
  1982年   95篇
  1981年   133篇
  1980年   85篇
  1979年   112篇
  1978年   53篇
  1977年   51篇
  1976年   45篇
  1974年   46篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
X Dong  M He  X Song  B Lu  Y Yang  S Zhang  N Zhao  L Zhou  Y Li  X Zhu  R Hu 《Diabetic medicine》2007,24(12):1482-1486
AIMS: Our aim was to assess performances of the Cockcroft-Gault and simplified Modification of Diet in Renal Disease (MDRD) formulae in estimating glomerular filtration rate (GFR) in Chinese diabetic populations and their association with vascular risks. METHODS: A total of 1009 patients with Type 2 diabetes were categorized into low estimated GFR groups (GFR < 60 ml/min/1.73 m(2)) and control groups by the two equations. The performances of these formulae were assessed at different stages of kidney function. Carotid artery intima-media thickness (IMT) and the prevalence of diabetic retinopathy or albuminuria were compared among the groups. The ability of these formulae to identify established vascular risk markers using sensitivity, specificity, positive and negative predictive values were also compared. RESULTS: The prevalence of low estimated GFR was 32.7% with the Cockcroft-Gault formula and 5.2% with the MDRD formula, respectively. In low estimated GFR subjects by the MDRD formula, IMT was significantly thicker than those by the Cockcroft-Gault formula (1.2 mm vs. 1.0 mm; P < 0.05), with a higher prevalence of albuminuria (78.4 vs. 52.8%, P < 0.05) and diabetic retinopathy (46.5 vs. 30.5%; P < 0.05). The Cockcroft-Gault formula gave a specificity of 71.7% and a sensitivity of 37.0%, and the MDRD formula gave a specificity of 96.6% and a sensitivity of 7.9% in estimating low GFR relevant for established vascular risks. CONCLUSIONS: These formulae performed differently in Chinese diabetic populations. The simplified MDRD formula is minimally superior to the Cockcroft-Gault formula for its high specificity and positive predictive values in estimating low GFR relevant for vascular risks.  相似文献   
92.
A study on the pathologic findings after recession and resection of extraocular muscles in rabbits was performed. Fibrosis of the extraocular muscles increased with time, which showed no difference between the recessed and resected muscles. Inflammation and foreign body reaction decreased with time, which showed no difference between the recessed and resected muscles. Adhesions of extraocular muscles to the sclera were observed from one month after the operation. The resected muscles showed milder adhesion to the sclera than the recessed ones. The operated extraocular muscles showed atrophies at one month, which showed no difference between the recessed and resected muscles. According to our results, when reoperation is needed, fibrosis of the extraocular muscles after recession and resection should be considered when making a decision on the amount of muscle to be recessed and resected.  相似文献   
93.
94.
以曼氏血吸虫的虫卵和成虫免疫家兔后所产生的特异性抗体,可用以日本血吸虫虫卵、尾蚴和成虫为抗原分别进行的COP,CHR和ELACIEP测出,表明两种人体血吸虫存有显著的交叉抗原成分。应用此种血清交叉反应性,以检测抗异种人体血吸虫的抗体,似有效而可取的,可用以辅助诊断援外回国人员是否感染国外人体血吸虫病。  相似文献   
95.
张占香  杨树青 《护理研究》2005,19(18):1650-1651
医院感染是指病人在入院时不存在,也不处于潜伏期,而是在医院内发生的感染,也包括在医院里获得治疗,出院后发病的病人感染[1].癌症病人是一个特殊的群体,是医院感染的易感和高危人群,由于疾病本身引起消瘦无力、营养不良、甚至恶病质,免疫力低下、再加上接受放射线治疗后引起骨髓功能抑制、消化道功能障碍、皮肤反应及其他副反应等危险因素,医院感染发生率高,因此放疗科的医院感染控制是非常重要的工作.本文通过对我院放疗科病房2003年8月-2004年4月住院病人137例中发生医院感染病例12例进行分析,总结出一些控制医院感染的方法,现将其介绍如下.……  相似文献   
96.
97.
Molecular determinants of cetuximab efficacy.   总被引:17,自引:0,他引:17  
PURPOSE: To investigate whether mRNA expression levels of cyclin D1 (CCND1), cyclooxygenase 2 (Cox-2), epidermal growth factor receptor (EGFR), interleukin 8 (IL-8), and vascular endothelial growth factor (VEGF), all members of the EGFR signaling pathway, are associated with clinical outcome in patients with EGFR-expressing metastatic colorectal cancer (CRC) treated with cetuximab. PATIENTS AND METHODS: Thirty-nine patients with metastatic CRC, refractory to both irinotecan and oxaliplatin, were enrolled on IMCL-0144 and treated with single-agent cetuximab. The intratumoral mRNA levels of CCND1, Cox-2, EGFR, IL-8, and VEGF were assessed from paraffin-embedded tissue samples using laser-capture microdissection and quantitative real-time polymerase chain reaction. RESULTS: There were 21 women and 18 men with a median age of 64 years (range, 35 to 83 years). Higher gene expression levels of VEGF were associated with resistance to cetuximab (P = .038; Kruskal-Wallis test). The combination of low gene expression levels of Cox-2, EGFR, and IL-8 was significantly associated with overall survival (13.5 v 2.3 months; P = .028; log-rank test). Both findings were independent of skin toxicity that was itself significantly correlated to survival. Patients with a lower mRNA amount of EGFR had a longer overall survival compared with patients that had a higher mRNA amount (7.3 v 2.2 months; P = .09; log-rank test). Patients with lower expression of Cox-2 had a significantly higher rate of grade 2 to 3 skin reactions under cetuximab treatment. CONCLUSION: This pilot study suggests that gene expression levels of Cox-2, EGFR, IL-8, and VEGF in patients with metastatic CRC may be useful markers of clinical outcome in single-agent cetuximab treatment.  相似文献   
98.
Introduction and Aims. Different self‐report methods tend to produce different estimates of alcohol consumption. The present study compares differences in rates and risk levels based on responses to a modified version of the Daily Drinking Questionnaire (m‐DDQ) and quantity‐frequency (QF) questions. Design and Methods. The sample comprised 2082 university students, 61% of whom were female and 39% male with a mean age of 23.5 years. An email containing an online link to a brief six‐question survey was emailed to students enrolled in participating faculties at the University of Wollongong, Australia. Current drinkers completed m‐DDQ and QF questions about alcohol consumption. Results. QF methods identified significantly lower estimates of consumption (Mean = 9.15, SD = 12.51) compared with m‐DDQ (Mean = 13.06, SD = 14.07). Allocation to risk categories based on the Australian Alcohol Guidelines were conducted for both the m‐DDQ and QF methods. Almost twice as many students were found to be drinking at levels considered risky using the m‐DDQ method compared with QF. In addition, the relative rank order of participants varied significantly between the two methods. Discussion and Conclusions. The m‐DDQ method identified higher rates of drinking and categorised almost twice as many individuals into risky categories of drinking compared with QF. Such variations have major implications for identification of risk groups in health promotion or prevention programs.[Utpala‐Kumar R, Deane FP. Rates of alcohol consumption and risk status among Australian university students vary by assessment questions. Drug Alcohol Rev 2009]  相似文献   
99.
Up to 20% of patients develop venographically proven deep-vein thrombosis after elective orthopedic surgery even under the cover of heparin or low molecular weight heparin. The extent to which the chronic inflammation of osteoarthritis requiring elective orthopedic surgery alters in-vivo coagulation and whether any specific alteration influences the development of postoperative thrombosis are unknown. This study compared the concentrations of activated factor VII (FVIIa), tissue factor pathway inhibitor (TFPI), activated factor X (FXa)-TFPI, thrombin-antithrombin, and prothrombin fragment 1+2 (F1+2) in plasmas of 535 healthy individuals (ages 17-76) with those in the preoperative plasmas of 306 arthritis patients (ages 30-92) scheduled for elective knee or hip replacement surgery. C-reactive protein was also measured in the plasmas of approximately 15% of the participants. Age-adjusted concentrations of FVIIa, F1+2, and C-reactive protein were higher in patients than controls, while the concentrations of thrombin-antithrombin, TFPI and FXa-TFPI were similar. Chronic inflammation in the patients was thus associated with increased coagulation in vivo. Without compensatory increases in the concentrations of TFPI (natural inhibitor of prothrombinase), the elevated concentrations of FVIIa in the preoperative plasmas and the trauma associated with surgery may enhance the risk for developing postoperative deep-vein thrombosis.  相似文献   
100.
Summary We prospectively examined bone growth patterns in 894 children aged 6–17 years at the baseline visit, with a 6-year follow-up. Results show bone “tracking” over a six-year interval and sexual dimorphism of bone attained levels and timing of peak bone growth. Our findings underscore childhood and adolescence as critical periods for building bone and developing gender differences. Introduction Bone growth patterns were prospectively examined in 894 Chinese children (496 males), aged 6–17 yrs, from a population-based twin cohort. Whole-body bone area (BA), bone mineral content (BMC), and bone mineral density (BMD) were measured by DEXA at baseline and a 6-yr follow-up. Methods Graphic smoothing plots and generalized estimating equations were used to model bone attained levels, growth, and “tracking”. Results Attained levels of BMC and BA increased curvilinearly with age. Male attained levels were higher than females after age ∼15 yr, but BMD was lower between 13–17 yrs (Tanner stage I to IV). In both genders, peak BMC and BMD growth lagged ∼2 yrs behind peak BA growth, which lagged 2 yrs behind peak height growth. Peak bone growth occurred 1–3 yrs later in males. Over the 6-yr follow-up, all bone measurements “tracked”, but “shifting” across ranks also occurred, and baseline tertile ranking influenced bone growth. Females with early menarche had higher attained levels than females with late menarche at age 12–13 yrs. Conclusion Our findings confirm and expand previous studies on peak bone growth conducted in Caucasian cohorts, particularly sexually dimorphic and maturational effects. The significant “tracking” of bone measurements in this 6-yr follow-up study underscores the importance that osteoporosis prevention should begin in childhood and adolescence. Fengxiu Ouyang and Binyan Wang contributed equally to this article. Source(s) of support: This study is supported in part by grant R01 HD049059, R01 HL0864619 and R01 AR045651 from the National Institute of Health and by the Food Allergy Project.  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