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   39154篇
  免费   3604篇
  国内免费   1092篇
耳鼻咽喉   82篇
儿科学   4011篇
妇产科学   366篇
基础医学   3764篇
口腔科学   212篇
临床医学   3691篇
内科学   6622篇
皮肤病学   360篇
神经病学   1566篇
特种医学   404篇
外国民族医学   6篇
外科学   1288篇
综合类   6164篇
现状与发展   12篇
预防医学   2186篇
眼科学   337篇
药学   2774篇
  17篇
中国医学   4968篇
肿瘤学   5020篇
  2024年   102篇
  2023年   613篇
  2022年   971篇
  2021年   1729篇
  2020年   1617篇
  2019年   1288篇
  2018年   1202篇
  2017年   1504篇
  2016年   1433篇
  2015年   1487篇
  2014年   2569篇
  2013年   2508篇
  2012年   2051篇
  2011年   2326篇
  2010年   1673篇
  2009年   1617篇
  2008年   1559篇
  2007年   1573篇
  2006年   1519篇
  2005年   1348篇
  2004年   1287篇
  2003年   1045篇
  2002年   875篇
  2001年   859篇
  2000年   722篇
  1999年   657篇
  1998年   648篇
  1997年   510篇
  1996年   554篇
  1995年   569篇
  1994年   503篇
  1993年   460篇
  1992年   429篇
  1991年   420篇
  1990年   340篇
  1989年   353篇
  1988年   330篇
  1987年   263篇
  1986年   244篇
  1985年   382篇
  1984年   301篇
  1983年   196篇
  1982年   253篇
  1981年   203篇
  1980年   158篇
  1979年   172篇
  1978年   106篇
  1977年   94篇
  1976年   96篇
  1975年   42篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Iron deficiency anemia is often listed among potential adverse effects of gastric acid-suppressive medications, given that gastric acidity promotes intestinal absorption of nonheme iron. Additionally, the antacid calcium carbonate can inhibit iron absorption. However, there is little direct clinical evidence that proton-pump inhibitors, histamine-2 receptor antagonists, or calcium carbonate cause iron deficiency anemia. Most case reports have had substantial limitations (e.g., minimal follow-up and presence of other causes of iron deficiency), and retrospective cohort studies have lacked sufficient patient-specific detail to make strong causal inferences. We present 2 cases—both with detailed, prospective 10-year follow-up—in which combinations of proton-pump inhibitors, histamine-2 receptor antagonists and calcium carbonate were clearly associated with development of iron deficiency anemia. Overt iron-deficiency anemia is probably uncommon in patients who use acid-modifying medications and who have no other conditions that predispose to iron deficiency. Nevertheless, clinicians should be aware of this potential complication, given widespread use of these agents.  相似文献   
22.
6-Mercaptopurine (6-MP) is commonly used for treatment of acute lymphoblastic leukemia (ALL). The incidence of hematotoxicity caused by this drug is quite high in Asians even using a standard low dosage regimen. The present study was aimed to elucidate the impact of thiopurine S-methyltransferase (TPMT), a nucleoside diphosphate-linked moiety X-type motif 15 (NUDT15), inosine triphosphatase (ITPA) and ATP Binding Cassette Subfamily C Member 4 (ABCC4) polymorphisms on hematotoxicity in pediatric patients who received a standard low starting dose of 6-MP. One hundred and sixty-nine pediatric patients were enrolled and their genotypes were determined. Patients who carried NUDT1513 and NUDT1512 genotypes were at a 10–15 fold higher risk of severe neutropenia than those of the wild-type during the early months of the maintenance phase. Risk of neutropenia was not significantly increased in patients with other NUDT15 variants as well as in patients with TPMT, ITPA or ABCC4 variants. These results suggest that NUDT15 polymorphisms particularly, NUDT1513 and NUDT1512, play major roles in 6-MP-induced severe hematotoxicity even when using a standard low dosage of 6-MP and genotyping of these variants is necessary in order to obtain precise tolerance doses and avoid severe hematotoxicity in pediatric patients.  相似文献   
23.
24.
25.

Background

The ZOE-50 (NCT01165177) and ZOE-70 (NCT01165229) phase 3 clinical trials showed that the adjuvanted recombinant zoster vaccine (RZV) was ≥90% efficacious in preventing herpes zoster in adults. Here we present a comprehensive overview of the safety data from these studies.

Methods

Adults aged ≥50 (ZOE-50) and ≥70 (ZOE-70) years were randomly vaccinated with RZV or placebo. Safety analyses were performed on the pooled total vaccinated cohort, consisting of participants receiving at least one dose of RZV or placebo. Solicited and unsolicited adverse events (AEs) were collected for 7 and 30?days after each vaccination, respectively. Serious AEs (SAEs) were collected from the first vaccination until 12?months post-last dose. Fatal AEs, vaccination-related SAEs, and potential immune-mediated diseases (pIMDs) were collected during the entire study period.

Results

Safety was evaluated in 14,645 RZV and 14,660 placebo recipients. More RZV than placebo recipients reported unsolicited AEs (50.5% versus 32.0%); the difference was driven by transient injection site and solicited systemic reactions that were generally seen in the first week post-vaccination. The occurrence of overall SAEs (RZV: 10.1%; Placebo: 10.4%), fatal AEs (RZV: 4.3%; Placebo: 4.6%), and pIMDs (RZV: 1.2%; Placebo: 1.4%) was balanced between groups. The occurrence of possible exacerbations of pIMDs was rare and similar between groups. Overall, except for the expected local and systemic symptoms, the safety results were comparable between the RZV and Placebo groups irrespective of participant age, gender, or race.

Conclusions

No safety concerns arose, supporting the favorable benefit-risk profile of RZV.  相似文献   
26.
27.
28.
目的:观察糖尿病小鼠小肠绒毛杯状细胞分泌的黏原颗粒是否改变,为进一步研究糖尿病的消化系统并发症提供形态学基础。方法分别选取3,5,8,10月龄db/db糖尿病小鼠及相应年龄段的db/+m正常小鼠,每组6只,标本用4%多聚甲醛灌流固定后,从距Treitz韧带约10 cm处切下一段空肠,用PAS染色方法对小肠杯状细胞分泌的黏原颗粒进行观察。结果糖尿病组小肠绒毛易被破坏,糖尿病组中杯状细胞的分泌物比同月份正常对照组显著增加(P<0.05);糖尿病组中3月龄的杯状细胞分泌物最多,8月龄最少,并且8月龄分别与3月龄、5月龄比较均存在着显著差异(P<0.05);正常对照组随月龄增长无显著性差异(P>0.05)。结论糖尿病时杯状细胞分泌物增多可能对小肠绒毛有保护作用。  相似文献   
29.
ObjectivesVitamin D deficiency is prevalent among older adults. We aimed to study whether residential greenness could alter serum 25(OH)D concentrations as a possible mechanism of residential greenness's positive health effects.DesignA longitudinal cohort study.Setting and ParticipantsWe included older adults aged ≥65 years from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) with follow-up between 2012 and 2014.MethodsWe measured residential greenness by calculating annual average Normalized Difference Vegetation Index (NDVI) in a 500 m radius by using satellite images around each participant's residential address. Serum 25-hydroxyvitamin D (25(OH)D) concentration was dichotomized into 2 categories: nondeficiency (≥50 nmol/L) and deficiency (<50 nmol/L). We used the generalized estimating equation to examine the relationship between annual average NDVI and serum 25(OH)D.ResultsWe included 1336 participants in our analysis. The annual average NDVI was 0.49, and mean serum 25(OH)D was 43 nmol/L at baseline. Each 0.1-unit increase in annual average NDVI was associated with a 13% higher odds of vitamin D nondeficiency [95% confidence interval (CI): 1.01, 1.26]. The association was stronger among men [odds ratio (OR): 1.17, 95% CI: 1.02, 1.35] than women (OR: 1.08, 95% CI: 0.91, 1.29) and also stronger among those who were free of activities of daily living (ADL) disability at baseline (OR: 1.12, 95% CI: 1.00, 1.25). During the follow-up period, the participants who lived in greener areas were more likely to have an improved, rather than stable or deteriorated, vitamin D status (OR: 1.94, 95% CI: 1.51, 2.51).Conclusions and ImplicationsOur study suggests that higher levels of residential greenness are associated with higher serum 25(OH)D concentrations, which has implications for prevention of vitamin D deficiency among older adults.  相似文献   
30.
目的评价血液科白血病疾病护理中应用健康教育的临床效果,为白血病护理工作提供参考。方法选择医院收治的白血病患者,总计60例。进行白血病患者随机分组护理,对照组与试验组各30例白血病患者,分别采取常规护理和常规护理+健康教育,比较2组白血病患者的负性情绪、自我效能状况评分以及护理满意度、护理依从率。结果试验组白血病患者干预后SAS、SDS、GSES评分均明显优于对照组,护理满意度与护理依从率均明显高于对照组,指标差异具有统计学意义,P>0.05。结论血液科白血病治疗期间配合落实常规护理、健康教育可以在提高患者自我效能的同时提高患者的依从性,符合患者身心护理需求,整体护理效果显著。  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