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   294626篇
  免费   6992篇
  国内免费   156篇
耳鼻咽喉   2922篇
儿科学   11918篇
妇产科学   7063篇
基础医学   32972篇
口腔科学   4424篇
临床医学   20906篇
内科学   53451篇
皮肤病学   4054篇
神经病学   25600篇
特种医学   14196篇
外国民族医学   32篇
外科学   48355篇
综合类   3924篇
一般理论   29篇
预防医学   24091篇
眼科学   6272篇
药学   17784篇
  2篇
中国医学   971篇
肿瘤学   22808篇
  2018年   22799篇
  2017年   18121篇
  2016年   20582篇
  2015年   2168篇
  2014年   2457篇
  2013年   3211篇
  2012年   10167篇
  2011年   24221篇
  2010年   20790篇
  2009年   13457篇
  2008年   22765篇
  2007年   25188篇
  2006年   4274篇
  2005年   6028篇
  2004年   7184篇
  2003年   7989篇
  2002年   6100篇
  2001年   7404篇
  2000年   7526篇
  1999年   6125篇
  1998年   1859篇
  1997年   1786篇
  1996年   1446篇
  1995年   1330篇
  1994年   1214篇
  1993年   1209篇
  1992年   3902篇
  1991年   3725篇
  1990年   3774篇
  1989年   3513篇
  1988年   3143篇
  1987年   3022篇
  1986年   2884篇
  1985年   2722篇
  1984年   2017篇
  1983年   1686篇
  1982年   980篇
  1981年   953篇
  1980年   822篇
  1979年   1871篇
  1978年   1399篇
  1977年   1147篇
  1976年   968篇
  1975年   1229篇
  1974年   1294篇
  1973年   1232篇
  1972年   1094篇
  1971年   1025篇
  1970年   938篇
  1969年   838篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Maternal Zika virus infection (ZIKV) has serious health consequences for unborn offspring. Knowledge about prevention is critical to reducing risk, yet what women in the high-risk US–Mexico border region know about protecting themselves and their babies from ZIKV is mostly unknown. This study aimed to assess knowledge of ZIKV among pregnant and inter-conception women and to identify sources of information that might address knowledge gaps. Clients in five federally-funded, border region Healthy Start programs (N?=?326) were interviewed in late 2016 about their knowledge of ZIKV prevention methods and whether they believed themselves or their babies to be at risk. Sources of information about ZIKV and demographic characteristics were also measured. Chi square tests identified important associations between variables; adjusted odds ratios (AOR) and 95% confidence intervals for knowledge and beliefs were calculated. Among the 305 women aware of ZIKV, 69.5% could name two ways to prevent infection. Only 16.1% of women named using condoms or abstaining from sex as a prevention method. While 75.3% heard about ZIKV first from TV/radio, just 9.5% found the information helpful. Women who received helpful information from health care providers had greater odds of knowing two prevention methods (AOR?=?2.0; 1.1–3.7), when to test for ZIKV (AOR?=?5.2; 2.1–13.2), and how long to delay pregnancy after infection in a male partner (AOR?=?1.9; 1.1–3.2). Those who said web-based and social media sources were helpful had greater odds of knowing when to test for ZIKV (AOR?=?2.8; 1.3–6.3). Results can inform messaging for safe pregnancy and ZIKV prevention.  相似文献   
62.
This study includes a comparison analysis of how community resilience and its influence factor of community attachment were changed before and after the closing of the hospital in the rural community. In order to analyze the influence factors of healthcare and medical vulnerability on community resilience, as well as the mean difference from before and after the closing of the hospital, this study conducted matching sample t test, hierarchical regression analysis, difference in differences (DID) analysis. The results indicate that community attachment consists of such factors as closeness, preference, affective bond, and identity, and they showed significance in confidence. It showed that resilience and community attachment are lower after closing than before closing. Moreover, as a result of DID analysis where the variation of community attachment affects community resilience, closeness together with closeness had an influence on the community resilience. It needs to expand public projects to improve the settlement environment of the basic local government, and in particular, it should consider various support measures to overcome vulnerabilities in the healthcare and medical sector.  相似文献   
63.
64.
65.
While colorectal cancer (CRC) screening rates have been increasing in the general population, rates are considerably lower in Federally Qualified Health Centers (FQHCs), which serve a large proportion of uninsured and medically vulnerable patients. Efforts to screen eligible patients must be accelerated if we are to reach the national screening goal of 80% by 2018 and beyond. To inform this work, we conducted a survey of key informants at FQHCs in eight states to determine which evidence-based interventions (EBIs) to promote CRC screening are currently being used, and which implementation strategies are being employed to ensure that the interventions are executed as intended. One hundred and forty-eight FQHCs were invited to participate in the study, and 56 completed surveys were received for a response rate of 38%. Results demonstrated that provider reminder and recall systems were the most commonly used EBIs (44.6%) while the most commonly used implementation strategy was the identification of barriers (84.0%). The mean number of EBIs that were fully implemented at the centers was 2.4 (range 0–7) out of seven. Almost one-quarter of respondents indicated that their FQHCs were not using any EBIs to increase CRC screening. Full implementation of EBIs was correlated with higher CRC screening rates. These findings identify gaps as well as the preferences and needs of FQHCs in selecting and implementing EBIs for CRC screening.  相似文献   
66.
The list of motives by Kanin (1994) is the most cited list of motives to file a false allegation of rape. Kanin posited that complainants file a false allegation out of revenge, to produce an alibi or to get sympathy. A new list of motives is proposed in which gain is the predominant factor. In the proposed list, complainants file a false allegation out of material gain, emotional gain, or a disturbed mental state. The list can be subdivided into eight different categories: material gain, alibi, revenge, sympathy, attention, a disturbed mental state, relabeling, or regret. To test the validity of the list, a sample of 57 proven false allegations were studied at and provided by the National Unit of the Dutch National Police (NU). The complete files were studied to ensure correct classification by the NU and to identify the motives of the complainants. The results support the overall validity of the list. Complainants were primarily motivated by emotional gain. Most false allegations were used to cover up other behavior such as adultery or skipping school. Some complainants, however, reported more than one motive. A large proportion, 20% of complainants, said that they did not know why they filed a false allegation. The results confirm the complexity of motivations for filing false allegations and the difficulties associated with archival studies. In conclusion, the list of Kanin is, based on the current results, valid but insufficient to explain all the different motives of complainants to file a false allegation.  相似文献   
67.
68.
A recently published framework for the diagnosis of Alzheimer’s disease (AD) in research studies would allow diagnosis on the sole basis of two biomarkers (β-amyloid and pathologic tau), even in people with no objective or subjective memory or cognitive changes. This revision will have substantial implications for future Alzheimer’s research, and the changes should be rigorously evaluated before widespread adoption. We propose three principles for evaluating any revision to diagnostic frameworks for AD: (1) does the revision improve the validity of the diagnosis; (2) does the revision improve the reliability or reduce the expense of the diagnosis; and (3) will the revision foster innovative and rigorous research across populations. The new diagnostic framework is unlikely to achieve any of these goals. Instead, it has the potential to handicap future researchers, and slow progress towards identifying effective strategies to prevent or treat AD.  相似文献   
69.
Little is known about the combined associations of cardiorespiratory fitness (CRF) and hand grip strength (GS) with mortality in general adult populations. The purpose of this study was to compare the relative risk of mortality for CRF, GS, and their combination. In UK Biobank, a prospective cohort of >?0.5 million adults aged 40–69 years, CRF was measured through submaximal bike tests; GS was measured using a hand-dynamometer. This analysis is based on data from 70,913 men and women (832 all-cause, 177 cardiovascular and 503 cancer deaths over 5.7-year follow-up) who provided valid CRF and GS data, and with no history of heart attack/stroke/cancer at baseline. Compared with the lowest CRF category, the hazard ratio (HR) for all-cause mortality was 0.76 [95% confidence interval (CI) 0.64–0.89] and 0.65 (95% CI 0.55–0.78) for the middle and highest CRF categories, respectively, after adjustment for confounders and GS. The highest GS category had an HR of 0.79 (95% CI 0.66–0.95) for all-cause mortality compared with the lowest, after adjustment for confounders and CRF. Similar results were found for cardiovascular and cancer mortality. The HRs for the combination of highest CRF and GS were 0.53 (95% CI 0.39–0.72) for all-cause mortality and 0.31 (95% CI 0.14–0.67) for cardiovascular mortality, compared with the reference category of lowest CRF and GS: no significant association for cancer mortality (HR 0.70; 95% CI 0.48–1.02). CRF and GS are both independent predictors of mortality. Improving both CRF and muscle strength, as opposed to either of the two alone, may be the most effective behavioral strategy to reduce all-cause and cardiovascular mortality risk.  相似文献   
70.
With greater access to regression-based methods for confounder control, the etiologic study with individual matching, analyzed by classical (calculator) methods, lost favor in recent decades. This design was costly, and the data sometimes mis-analyzed. Now, with Big Data, individual matching becomes an economical option. To many, however, conditional logistic regression, commonly used to estimate the incidence density ratio parameter, is somewhat of a black box whose output is not easily checked. An epidemiologist-statistician pair recently proposed a new estimator that is easily applied to data from individually-matched series with a 2:1 ratio (and no other confounding variables) using just a hand calculator or spreadsheet. Surprisingly—or possibly not—they overlooked classical estimators developed in earlier decades. This prompts me to re-introduce some of these, to highlight their considerable flexibility and ease of use, and to update them. Nowadays, for any matching ratio (M:1), the Maximum Likelihood result can be easily computed from data gathered under the matched design in two different ways, each using just the summary data. One is via any binomial regression program that allows offsets, applied to just M ‘rows’ of data. The other is by hand! The aim of this note is not to save on computation; instead, it is to make connections between classical and regression-based methods, to promote terminology that reflects the concepts and structure of the etiologic study, and to focus attention on what parameter is being estimated.  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