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   277693篇
  免费   40861篇
  国内免费   2758篇
耳鼻咽喉   6792篇
儿科学   8757篇
妇产科学   4656篇
基础医学   20235篇
口腔科学   4142篇
临床医学   39530篇
内科学   73396篇
皮肤病学   9458篇
神经病学   27129篇
特种医学   10571篇
外国民族医学   5篇
外科学   59250篇
综合类   2454篇
现状与发展   73篇
一般理论   184篇
预防医学   18618篇
眼科学   6292篇
药学   10070篇
  2篇
中国医学   183篇
肿瘤学   19515篇
  2023年   5169篇
  2022年   1864篇
  2021年   5116篇
  2020年   7146篇
  2019年   4193篇
  2018年   9645篇
  2017年   8991篇
  2016年   10206篇
  2015年   10699篇
  2014年   18725篇
  2013年   20779篇
  2012年   13515篇
  2011年   14072篇
  2010年   15002篇
  2009年   18494篇
  2008年   13994篇
  2007年   12806篇
  2006年   15004篇
  2005年   12684篇
  2004年   11459篇
  2003年   10275篇
  2002年   9873篇
  2001年   5242篇
  2000年   4270篇
  1999年   4669篇
  1998年   5321篇
  1997年   4842篇
  1996年   4506篇
  1995年   4317篇
  1994年   2903篇
  1993年   2546篇
  1992年   2303篇
  1991年   2290篇
  1990年   1897篇
  1989年   1982篇
  1988年   1733篇
  1987年   1535篇
  1986年   1547篇
  1985年   1490篇
  1984年   1489篇
  1983年   1425篇
  1982年   1724篇
  1981年   1488篇
  1980年   1333篇
  1979年   839篇
  1978年   940篇
  1977年   971篇
  1976年   733篇
  1975年   715篇
  1974年   639篇
排序方式: 共有10000条查询结果,搜索用时 765 毫秒
71.
72.
Using data on waterfowl band recoveries, we identified spatially explicit hotspots of concentrated waterfowl movement to predict occurrence and spatial spread of a novel influenza A virus (clade 2.3.4.4) introduced from Asia by waterfowl from an initial outbreak in North America in November 2014. In response to the outbreak, the hotspots of waterfowl movement were used to help guide sampling for clade 2.3.4.4 viruses in waterfowl as an early warning for the US poultry industry during the outbreak . After surveillance sampling of waterfowl, we tested whether there was greater detection of clade 2.3.4.4 viruses inside hotspots. We found that hotspots defined using kernel density estimates of waterfowl band recoveries worked well in predicting areas with higher prevalence of the viruses in waterfowl. This approach exemplifies the value of ecological knowledge in predicting risk to agricultural security.  相似文献   
73.

Background

In a pooled analysis of the phase 3 Controlled Myelofibrosis Study With Oral JAK Inhibitor Treatment I (COMFORT-I) and COMFORT-II clinical trials, adult patients with intermediate-2 or high-risk myelofibrosis who received oral ruxolitinib at randomization or after crossover from placebo or best available therapy (BAT) had improved overall survival (OS).

Methods

This post hoc analysis of pooled COMFORT data examined relevant disease outcomes based on the disease duration (≤12 or >12 months from diagnosis) before ruxolitinib initiation.

Results

The analysis included 525 patients (ruxolitinib: ≤12 months, n = 84; >12 months, n = 216; placebo/BAT: ≤12 months, n = 66; >12 months, n = 159); the median age was 65.0–70.0 years. Fewer thrombocytopenia and anemia events were observed among patients who initiated ruxolitinib treatment earlier. At Weeks 24 and 48, the spleen volume response (SVR) was higher for patients who initiated ruxolitinib earlier (47.6% vs. 32.9% at Week 24, p = .0610; 44.0% vs. 26.9% at Week 48, p = .0149). In a multivariable analysis of factors associated with spleen volume reduction, a logistic regression model that controlled for confounding factors found that a significantly greater binary reduction was observed among patients with shorter versus longer disease duration (p = .022). At Week 240, OS was significantly improved among patients who initiated ruxolitinib earlier (63% [95% CI, 51%‒73%] vs. 57% [95% CI, 49%‒64%]; hazard ratio, 1.53; 95% CI, 1.01‒2.31; p = .0430). Regardless of disease duration, a longer OS was observed for patients who received ruxolitinib versus those who received placebo/BAT.

Conclusions

These findings suggest that earlier ruxolitinib initiation for adult patients with intermediate-2 and high-risk myelofibrosis may improve clinical outcomes, including fewer cytopenia events, durable SVR, and prolonged OS.

Plain Language Summary

  • Patients with myelofibrosis, a bone marrow cancer, often do not live as long as the general population. These patients may also have an enlarged spleen and difficult symptoms such as fatigue.
  • Two large clinical trials showed that patients treated with the drug ruxolitinib lived longer and had improved symptoms compared to those treated with placebo or other standard treatments.
  • Here it was examined whether starting treatment with ruxolitinib earlier (i.e., within a year of diagnosis) provided benefits versus delaying treatment.
  • Patients who received ruxolitinib within a year of diagnosis lived longer and experienced fewer disease symptoms than those whose treatment was delayed.
  相似文献   
74.
75.
76.
Ovarian cancer is the fourth most common cause of cancer-related death in women in the developed world, and one of the most heritable cancers. One of the most significant risk factors for epithelial ovarian cancer (EOC) is a family history of breast and/or ovarian cancer. Combined risk factors can be used in models to stratify risk of EOC, and aid in decisions regarding risk-reduction strategies. Germline pathogenic variants in EOC susceptibility genes including those involved in homologous recombination and mismatch repair pathways are present in approximately 22% to 25% of EOC. These genes are associated with an estimated lifetime risk of EOC of 13% to 60% for BRCA1 variants and 10% to 25% for BRCA2 variants, with lower risks associated with remaining genes. Genome-wide association studies have identified single nucleotide polymorphisms (SNPs) thought to explain an additional 6.4% of the familial risk of ovarian cancer, with 34 susceptibility loci identified to date. However, an unknown proportion of the genetic component of EOC risk remains unexplained. This review comprises an overview of individual genes and SNPs suspected to contribute to risk of EOC, and discusses use of a polygenic risk score to predict individual cancer risk more accurately.  相似文献   
77.
78.
79.
80.
PurposeTwitter is an increasingly popular social media platform within the health care community. The objective of this analysis is to characterize the profile of radiation oncology–related tweets and Twitter users over the past 6 years.Methods and MaterialsUsing the web-based social media analytics platform Symplur Signals, we filtered tweets containing at least 1 of the following hashtags or key words: #radonc, #radiationoncology, "rad onc," or "radiation oncology." We evaluated radiation oncology–related Twitter activity between October 2014 and March 2020 for tweet frequency, tweet content, and individuals or groups posting tweets. We identified the most influential Twitter users contributing to radiation oncology–related tweets.ResultsFrom 2014 to 2020, the quarterly volume of radiation oncology–related tweets increased from 5027 to 29,763. Physicians contributed the largest growth in tweet volume. Academic radiation oncologists comprise 60% of the most influential Twitter accounts responsible for radiation oncology–related content. The number of radiation-oncology resident physicians on Twitter increased from 25 to 328 over the past 6 years, and 20% of radiation-oncology residency programs have a Twitter account. Seventy-one percent of radiation oncology–related tweets generated direct communication via mentions, and 59% of tweets contain links to external sources, including scientific articles.ConclusionsThe number of physicians contributing radiation oncology–related Twitter content has increased significantly in recent years. Academic radiation oncologists are the primary influencers of radiation oncology–related Twitter activity. Twitter is used by radiation oncologists to both professionally network and discuss findings related to the field. There remains the opportunity for radiation oncologists to broaden their audience on Twitter to encompass a more diverse community, including patients.  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