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   94144篇
  免费   7992篇
  国内免费   3485篇
耳鼻咽喉   819篇
儿科学   2053篇
妇产科学   1966篇
基础医学   11264篇
口腔科学   1498篇
临床医学   11457篇
内科学   15798篇
皮肤病学   1199篇
神经病学   6448篇
特种医学   3119篇
外国民族医学   38篇
外科学   10295篇
综合类   9391篇
现状与发展   15篇
一般理论   61篇
预防医学   8573篇
眼科学   1993篇
药学   8711篇
  53篇
中国医学   3102篇
肿瘤学   7768篇
  2024年   221篇
  2023年   1135篇
  2022年   2591篇
  2021年   3979篇
  2020年   2740篇
  2019年   2923篇
  2018年   3183篇
  2017年   2636篇
  2016年   2764篇
  2015年   3494篇
  2014年   4476篇
  2013年   5038篇
  2012年   7167篇
  2011年   7662篇
  2010年   4607篇
  2009年   3807篇
  2008年   5734篇
  2007年   5782篇
  2006年   5341篇
  2005年   4999篇
  2004年   4212篇
  2003年   3777篇
  2002年   3593篇
  2001年   1869篇
  2000年   1765篇
  1999年   1638篇
  1998年   1081篇
  1997年   1018篇
  1996年   798篇
  1995年   707篇
  1994年   597篇
  1993年   432篇
  1992年   575篇
  1991年   459篇
  1990年   436篇
  1989年   384篇
  1988年   313篇
  1987年   295篇
  1986年   238篇
  1985年   176篇
  1984年   136篇
  1983年   113篇
  1982年   84篇
  1981年   91篇
  1980年   50篇
  1979年   75篇
  1978年   41篇
  1974年   39篇
  1973年   37篇
  1972年   44篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Abstract: Background : Women are increasingly being asked to consider participating in medical research. We sought to investigate views of women who participated in and declined to participate in a study that was part of a program of maternity care research. Methods : An exploratory study using focus group interviews and semistructured interviews was conducted. A purposive sample of 17 postnatal women who had participated in research, from a hospital in the North West of England, were interviewed. An open coding mechanism to identify emergent themes was used for the analysis of data. Results : Of women who had not declined to participate in any research, the following themes were identified: altruism versus self‐protection, enhanced versus inferior care, professional guidance versus self‐direction, and welcome versus unacceptable methodology. Of women who had participated in some research but declined to participate in other research, the following themes were identified: feeling disempowered by the process, inability to believe equipoise existed, and practical inconvenience. Conclusions : These findings suggest that although health care researchers adopt an individualistic approach to care, they may fail to adopt a similar approach within research. What is important and acceptable to women needs to be ascertained to develop appropriate research strategies. This plan will ensure that research is carried out to the highest ethical standard, which may increase recruitment rates.  相似文献   
32.
Delta hepatitis virus infection in China   总被引:1,自引:0,他引:1  
To assess the prevalence, epidemiological features and prognostic implications of hepatitis D (Delta) in Sichuan Province, The People's Republic of China, 649 sera (515 from HBsAg positive patients and 134 from HBsAg negative subjects) were tested by radioimmunoassay (RIA) for antibody to the hepatitis D virus (anti-HD). Forty-seven sera (7.2%) showed some degree of reactivity. Serial dilutions of these sera indicated that prozoning was not responsible for the equivocal results. Thirty-four of the 47 sera were submitted under code to a second laboratory for independent analysis. According to those results anti-HD antibodies were detected in four of these sera. The overall prevalence of anti-HD in the HBsAg positive patients therefore was 0.8% (4/515). On the basis of clinical, biochemical and histological data 427 HBsAg positive sera were further divided into acute Type B hepatitis, chronic Type B hepatitis, healthy carrier state and hepatocellular carcinoma (HCC) subgroups. Two of 65 (3.1%) anti-HD positive sera belonged to the acute Type B hepatitis group; one of 104 (0.9%), the chronic Type B hepatitis group and one of 246 (0.4%), the healthy carrier group. No antibody was detected in sera from 12 HBsAg positive HCC patients. All HBsAg negative patients were negative for anti-HD antibody. The results of this study indicate that despite a high prevalence of hepatitis B virus infection, positive serology for delta virus is uncommon in Sichuan Province, The People's Republic of China.  相似文献   
33.
PURPOSE: Epidermal growth factor receptor is expressed in pediatric malignant solid tumors. We conducted a phase I trial of gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, in children with refractory solid tumors. PATIENTS AND METHODS: Gefitinib (150, 300, 400, or 500 mg/m2) was administered orally to cohorts of three to six patients once daily continuously until disease progression or significant toxicity. Pharmacokinetic studies were performed during course one (day 1 through 28). RESULTS: Of the 25 enrolled patients, 19 (median age, 15 years) were fully evaluable for toxicity and received 54 courses. Dose-limiting toxicity was rash in two patients treated with 500 mg/m2 and elevated ALT and AST in one patient treated with 400 mg/m2. The maximum-tolerated dose was 400 mg/m2/d. The most frequent non-dose-limiting toxicities were grade 1 or 2 dry skin, anemia, diarrhea, nausea, and vomiting. One patient with Ewing's sarcoma had a partial response. Disease stabilized for 8 to > or = 60 weeks in two patients with Wilms' tumor and two with brainstem glioma (one exophytic). At 400 mg/m2, the median peak gefitinib plasma concentration was 2.2 microg/mL (range, 1.2 to 3.6 microg/mL) and occurred at a median of 2.3 hours (range, 2.0 to 8.3 hours) after drug administration. The median apparent clearance and median half-life were 14.8 L/h/m2 (range, 3.8 to 24.8 L/h/m2) and 11.7 hours (range, 5.6 to 22.8 hours), respectively. Gefitinib systemic exposures were comparable with those associated with antitumor activity in adults. CONCLUSION: Oral gefitinib is well tolerated in children. Development of the drug in combination with cytotoxic chemotherapy will be pursued.  相似文献   
34.
35.
The first universal hepatitis B vaccination program for newborns in the world was launched in Taiwan in July 1984. Most studies on the effectiveness of hepatitis B vaccination focused on the seroprevalence of HBs Ag among children under 14 years old. Only few studies focused on the seropositivity of anti-HBs among adolescents aged 15–18 years old. The present study aimed to evaluate the impact of the nationwide hepatitis B vaccination program on the immunity to HBV infection and the necessity of boost among adolescents. In this study including eight annual seroprevalence surveys from 2000 to 2007, 2342 college entrants (1589 15-year-olds in group I and 753 18-year-olds in group II) and 1851 university freshmen (18-year-olds in group III) participated. Subjects identified anti-HBs, HBs Ag and anti-HBc negative were given boost three doses of HBV vaccine. The HBs Ag seroprevalence was 11.6%, 3.5% and 1.0% for participants who were born before 1984, 1984–1986 and after 1986. The anti-HBs-seropositive rates were significantly higher in group II (83.1%) than in group I (53.0%) and group III (53.5%). All 572 participants who were seronegative for anti-HBs, HBs Ag and anti-HBc became anti-HBs-seropositive after catch-up vaccination. It is concluded that the anti-HBs-seropositive rate decreased to 50% in 15 years after vaccination, and boost vaccination was 100% effective. The necessity and age for boost among anti-HBs negative adolescents and the timing of the first immunization should be further evaluated.  相似文献   
36.
Background The incidence rate of incisional hernias after open surgery has been reported to be higher than that of port site hernias after laparoscopic surgery. No studies have compared the costs for the health care system in treating those two types of hernia. Methods A systematic review was conducted to obtain the baseline data, and a decision analysis model was created to simulate the occurrence and recurrence of incisional and port site hernias. Results The overall risk of having incisional hernias was eight-times higher than that of having port site hernias (7.4% vs 0.9%). A cost savings of £93 per patient can be generated for the health care system in the UK. Similar results were obtained for Germany, Italy and France. Conclusions The additional treatment costs for incisional hernia should be taken into account when the costs of a surgery performed by open approach are compared with by laparoscopy.  相似文献   
37.
无线网络技术在医学仪器中的应用   总被引:1,自引:0,他引:1  
简要介绍无线网络技术的原理、特点及其在医学仪器中的应用.  相似文献   
38.
全同非典进行特死斗争过程中,医护人员表现出一种临危不惧、挺身而出、全力救治、不怕牺牲、恪尽职守、患者至上、竭诚服务、科学防治的“抗非典精神”值得宣传,学习和效法。  相似文献   
39.
Multiple options exist for the prevention of deep vein thrombosis (DVT) in medical inpatients. We sought to determine the cost-effectiveness of low-molecular-weight heparin (LMWH) relative to unfractionated heparin (UFH) for DVT prevention in this setting. We conducted a cost-effectiveness analysis from the perspective of a third-party payer employing a decision model and literature-based estimates for inputs. In the base-case analysis, LMWH had little impact on the rate of DVT. Despite higher acquisition costs, however, LMWHs resulted in net savings. Routine use of LMWH saves approximately US$89 per patient. The lower rate of heparin-induced thrombocytopenia (HIT) with LMWH accounted for this differential. Univariate sensitivity analysis revealed the model was moderately sensitive to the odds ratio of HIT with LMWH and the cost of HIT. Multivariate sensitivity analysis confirmed the LMWH approach dominated financially. 'Worst-case' scenario modeling, where LMWH actually increased the risk for DVT, had little effect on the rate of HIT, and was substantially more costly than UFH, still demonstrated that LMWHs were economically superior. Monte-Carlo simulation indicated the 95% confidence interval around the estimate for savings with LMWH ranged from US$7 to US$373. We conclude that, despite their higher cost, LMWHs for thromboprophylaxis in medical patients result in savings.  相似文献   
40.
HPLC法测定双红活血胶囊中黄芪甲苷的含量   总被引:2,自引:0,他引:2  
目的 测定双红活血胶囊中黄芪甲苷的含量。方法 采用高效液相色谱 (HPLC)法测定。结果 平均回收率为 1 0 0 .6%,CV =1 .62 %。结论 该方法简便 ,准确  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