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   1328622篇
  免费   102008篇
  国内免费   4231篇
耳鼻咽喉   16789篇
儿科学   43533篇
妇产科学   36361篇
基础医学   197130篇
口腔科学   35878篇
临床医学   129063篇
内科学   256354篇
皮肤病学   26362篇
神经病学   111528篇
特种医学   48132篇
外国民族医学   366篇
外科学   183786篇
综合类   28746篇
现状与发展   1篇
一般理论   462篇
预防医学   113677篇
眼科学   28939篇
药学   98702篇
  6篇
中国医学   3148篇
肿瘤学   75898篇
  2021年   10739篇
  2019年   11674篇
  2018年   16358篇
  2017年   12306篇
  2016年   13266篇
  2015年   15209篇
  2014年   20822篇
  2013年   32085篇
  2012年   44286篇
  2011年   46927篇
  2010年   27086篇
  2009年   24939篇
  2008年   42745篇
  2007年   45072篇
  2006年   45183篇
  2005年   43607篇
  2004年   41563篇
  2003年   39500篇
  2002年   38311篇
  2001年   60841篇
  2000年   62510篇
  1999年   52276篇
  1998年   14581篇
  1997年   13217篇
  1996年   12158篇
  1995年   12353篇
  1994年   11567篇
  1993年   10827篇
  1992年   41479篇
  1991年   40739篇
  1990年   39423篇
  1989年   37312篇
  1988年   34541篇
  1987年   33667篇
  1986年   32118篇
  1985年   30620篇
  1984年   22991篇
  1983年   19524篇
  1982年   11691篇
  1979年   20759篇
  1978年   14769篇
  1977年   12015篇
  1976年   11833篇
  1975年   12081篇
  1974年   14774篇
  1973年   14452篇
  1972年   13349篇
  1971年   12408篇
  1970年   11472篇
  1969年   10402篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
42.
neurogenetics - Human RNF213, which encodes the protein mysterin, is a known susceptibility gene for moyamoya disease (MMD), a cerebrovascular condition with occlusive lesions and compensatory...  相似文献   
43.
Monitoring variations in the functioning of the autonomic nervous system may help personalize training of runners and provide more pronounced physiological adaptations and performance improvements. We systematically reviewed the scientific literature comparing physiological adaptations and/or improvements in performance following training based on responses of the autonomic nervous system (ie, changes in heart rate variability) and predefined training. PubMed, SPORTDiscus, and Web of Science were searched systematically in July 2019. Keywords related to endurance, running, autonomic nervous system, and training. Studies were included if they (a) involved interventions consisting predominantly of running training; (b) lasted at least 3 weeks; (c) reported pre- and post-intervention assessment of running performance and/or physiological parameters; (d) included an experimental group performing training adjusted continuously on the basis of alterations in HRV and a control group; and (e) involved healthy runners. Five studies involving six interventions and 166 participants fulfilled our inclusion criteria. Four HRV-based interventions reduced the amount of moderate- and/or high-intensity training significantly. In five interventions, improvements in performance parameters (3000 m, 5000 m, Loadmax, Tlim) were more pronounced following HRV-based training. Peak oxygen uptake () and submaximal running parameters (eg, LT1, LT2) improved following both HRV-based and predefined training, with no clear difference in the extent of improvement in . Submaximal running parameters tended to improve more following HRV-based training. Research findings to date have been limited and inconsistent. Both HRV-based and predefined training improve running performance and certain submaximal physiological adaptations, with effects of the former training tending to be greater.  相似文献   
44.
45.
Background: Lay belief systems about the malleability of human attributes have been shown to impact behavior change in multiple domains. Addiction mindset—i.e., beliefs about the permanence (vs. malleability) of addiction — may affect cigarette smokers’ ability to quit, but this has never been examined. Objectives: The aims of the present research were to develop a measure of addiction mindset (study 1) and examine its associations with various psychological aspects of quitting smoking (study 2). Methods: In Study 1, using factor analysis of current smokers’ and nonsmokers’ (n?=?600) responses to 22 items designed to measure addiction mindset, we developed a reliable six-item Addiction Mindset Scale (AMS). In Study 2, adult smokers (n?=?200) completed the AMS, and measures of a number of psychological processes related to smoking. Results: Higher scores on the AMS, indicative of the belief that addiction is malleable (referred to as a growth mindset), were positively and significantly associated with greater motivation to quit, greater commitment to quitting, greater self-efficacy to abstain, less attribution of failure to lack of ability to change addiction, and fewer self-reported barriers to cessation (all p’s < .05). Conclusions: The results of this study show a relationship between the beliefs about the permanence of addiction and psychological processes relevant to quitting smoking. The findings underscore the potential of future research exploring how addiction mindsets relate to successful smoking cessation as well as other types of addictive behavior and how they can be applied to change people’s behavior.  相似文献   
46.
Pharmaceutical Chemistry Journal - An HPLC-MS method for simultaneous quantitative determination of a novel gestagenic pharmaceutical and two of its metabolites in rat and rabbit blood sera was...  相似文献   
47.

Purpose

Endovascular treatment with mechanical thrombectomy devices demonstrated high recanalization rates but functional outcome did not correlate with high rates of recanalization obtained. Patient selection prior to the endovascular treatment is very important in the final outcome of the patient. The primary aim of our study was to evaluate the prognostic value of posterior circulation Alberta Stroke Program Early CT Score (pc-ASPECTS) and Pons-Midbrain Index (PMI) scores in patients with Basilar Artery Occlusion (BAO) treated with successful angiographic recanalization after mechanical thrombectomy.

Methods

Retrospective single-center study including 18 patients between 2008 and 2013 who had acute basilar artery occlusion managed with endovascular treatment within 24 hours from symptoms onset and with successful angiographic recanalization. The patients were initially classified into two groups according to clinical outcome and mortality at 90 days. For analysis we also divided patients into groups based on pc-ASPECTS (≥8vs.< 8) and PMI (≥3vs.< 3) on non-contrast CT (NCCT) and CT Angiography Source Images (CTASI). Imaging data were correlated to clinical outcome and mortality rate.

Results

CTASI pc-ASPECTS, dichotomized at < 8 versus≥8, was associated with a favorable outcome (RR: 2.6; 95% CI: 1.3-5.2) and a reduced risk of death (RR: 6.5: 95% CI: 7.8-23.3). All patients that survived and were functionally independent had pc-ASPECTS score≥8. None of the 5 patients with CTASI pc-ASPECTS score less than 8 survived.

Conclusion

PC-ASPECTS on CTASI is helpful for predicting functional outcome after BAO recanalization with endovascular treatment. These results should be validated in a randomized controlled trial in order to decide whether or not to treat a patient with BAO.  相似文献   
48.
The UK has low breastfeeding rates, with socioeconomic disparities. The Assets‐based feeding help Before and After birth (ABA) intervention was designed to be inclusive and improve infant feeding behaviours. ABA is underpinned by the behaviour change wheel and offers an assets‐based approach focusing on positive capabilities of individuals and communities, including use of a Genogram. This study aimed to investigate feasibility of intervention delivery within a randomised controlled trial (RCT). Nulliparous women ≥16 years, (n = 103) from two English sites were recruited and randomised to either intervention or usual care. The intervention – delivered through face‐to‐face, telephone and text message by trained Infant Feeding Helpers (IFHs) – ran from 30‐weeks' gestation until 5‐months postnatal. Outcomes included recruitment rates and follow‐up at 3‐days, 8‐weeks and 6‐months postnatal, with collection of future full trial outcomes via questionnaires. A mixed‐methods process evaluation included qualitative interviews with 30 women, 13 IFHs and 17 maternity providers; IFH contact logs; and fidelity checking of antenatal contact recordings. This study successfully recruited women, including teenagers, from socioeconomically disadvantaged areas; postnatal follow‐up rates were 68.0%, 85.4% and 80.6% at 3‐days, 8‐weeks and 6‐months respectively. Breastfeeding at 8‐weeks was obtained for 95.1% using routine data for non‐responders. It was possible to recruit and train peer supporters to deliver the intervention with adequate fidelity. The ABA intervention was acceptable to women, IFHs and maternity services. There was minimal contamination and no evidence of intervention‐related harm. In conclusion, the intervention is feasible to deliver within an RCT, and a definitive trial required.  相似文献   
49.
50.
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