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   4193篇
  免费   397篇
  国内免费   9篇
耳鼻咽喉   12篇
儿科学   141篇
妇产科学   108篇
基础医学   428篇
口腔科学   80篇
临床医学   468篇
内科学   828篇
皮肤病学   55篇
神经病学   391篇
特种医学   364篇
外科学   493篇
综合类   122篇
一般理论   5篇
预防医学   425篇
眼科学   53篇
药学   358篇
中国医学   6篇
肿瘤学   262篇
  2021年   38篇
  2020年   32篇
  2019年   48篇
  2018年   72篇
  2017年   54篇
  2016年   64篇
  2015年   68篇
  2014年   92篇
  2013年   121篇
  2012年   208篇
  2011年   192篇
  2010年   116篇
  2009年   135篇
  2008年   186篇
  2007年   165篇
  2006年   168篇
  2005年   127篇
  2004年   123篇
  2003年   131篇
  2002年   107篇
  2001年   107篇
  2000年   115篇
  1999年   118篇
  1998年   79篇
  1997年   94篇
  1996年   99篇
  1995年   94篇
  1994年   83篇
  1993年   84篇
  1992年   86篇
  1991年   83篇
  1990年   96篇
  1989年   83篇
  1988年   86篇
  1987年   91篇
  1986年   84篇
  1985年   57篇
  1984年   48篇
  1983年   51篇
  1982年   55篇
  1981年   46篇
  1980年   38篇
  1979年   28篇
  1978年   35篇
  1977年   48篇
  1976年   38篇
  1975年   34篇
  1974年   31篇
  1972年   32篇
  1968年   27篇
排序方式: 共有4599条查询结果,搜索用时 0 毫秒
91.
With the development and increasing accessibility of new genomic tools such as next-generation sequencing, genome-wide association studies, and genomic stratification models, the debate on genetic discrimination in the context of life insurance became even more complex, requiring a review of current practices and the exploration of new scenarios. In this perspective, a multidisciplinary group of international experts representing different interests revisited the genetics and life insurance debate during a 2-day symposium ‘Life insurance: breast cancer research and genetic risk prediction seminar'' held in Quebec City, Canada on 24 and 25 September 2012. Having reviewed the current legal, social, and ethical issues on the use of genomic information in the context of life insurance, the Expert Group identified four main questions: (1) Have recent developments in genomics and related sciences changed the contours of the genetics and life insurance debate? (2) Are genomic results obtained in a research context relevant for life insurance underwriting? (3) Should predictive risk assessment and risk stratification models based on genomic data also be used for life insurance underwriting? (4) What positive actions could stakeholders in the debate take to alleviate concerns over the use of genomic information by life insurance underwriters? This paper presents a summary of the discussions and the specific action items recommended by the Expert Group.Access to genetic information by life insurers has been a topic of discussion for many years.1 The possibility of using genetic data to underwrite an applicant''s insurance policy has given rise to concerns about the emergence of ‘genetic discrimination''. Genetic discrimination in the field of life insurance is not necessarily illegal in that in insurance underwriting questions about health, family history of disease, or genetic information may constitute legal exceptions to antidiscrimination legislation.2, 3 Nevertheless, the expression ‘genetic discrimination'' has acquired public notoriety4 and we will use more neutral language in this paper.Countries including Canada, the United States, Russia, and Japan5 have chosen not to adopt laws specifically prohibiting access to genetic data for underwriting by life insurers.6 In these countries, life insurance underwriters treat genetic data like other types of medical or lifestyle data. However, a growing number of countries such as Belgium, France, and Norway5 have chosen to adopt laws to prevent or limit insurers'' access to genetic data for life insurance underwriting. Other countries including Finland and the United Kingdom have developed voluntary arrangements with the industry (ie moratoria) with similar objectives.7Life insurance is a private contract between the policy-holder and the insurer. Its principal role is to provide financial security to the beneficiaries in the event of the insured''s death.8 Because of this important role, life insurance is often required, or strongly recommended for those seeking loans to acquire primary social goods, like housing or cars.9 In Europe, a consequence of the advent of the welfare state is that private insurance has increasingly played a complementary and supplementary role to social insurance by offering additional security and protection to the population. Thus, in this region, insurance is often considered as a social good that allows individuals to live a comfortable life and as a tool to promote social integration.10 In other regions of the world, this social role of life insurance is also recognized to a lesser extent. Given this social role, equitable access to life insurance is perceived as a sensitive issue and cases of denial looked upon negatively in popular media. Although documented incidents of denial or of increased premiums on the basis of genetic information have remained limited to the context of a few relatively well known, highly penetrant, familial, adult-onset, genetic conditions,11 they have nevertheless generated significant public concern. Fear that insurers will have access to genetic information generated in a clinical or research setting for use in underwriting has been reported by several studies as a reason for non-participation in genetic research or recommended clinical genetic testing.12, 13, 14The clinical utility of genetic testing for monogenic disorders such as Huntington disease, and hereditary forms of cancer are well established.15 However, genomic risk profiles based on the known common susceptibility variants have limited utility in risk prediction at the individual level, although they could be used for risk stratification in prevention programmes in populations.16 Today, a new era of genomic research has made it increasingly affordable to scan the entire genome of an individual. Researchers and physicians can interpret these data together with medical and lifestyle information in the form of sophisticated risk prediction models.17 Moreover, improvement in computing technologies coupled with the Internet make predictive information increasingly available, whether through direct-to-consumer marketing of genetic tests, genetic data sharing online communities, or international research database projects. Given these important technological and scientific changes, and their impact on various stakeholders. The term ‘stakeholders'' is used in this text to refer to the following groups of individuals: actuaries (person who computes insurance risk and premium rates based on statistical data), academic researchers, community representatives, ethics committees, genetic counsellors, genomic researchers, human rights experts, insurers, governmental representatives, non-governmental organisations, patient representatives, physicians, policy makers, popular media, reinsurers (company in charge of calculating the risk and premium amount for insuring a particular customer), research participants, and underwriters (company or person in charge of calculating the risk involved in providing insurance for a particular customer and to decide how much should be paid for the premium). This list is not meant to be exhaustive as relevant new groups may emerge as this topic further develops in the coming years. A multidisciplinary group of international experts representing different interests (hereinafter ‘the Expert Group'') revisited the genetics and life insurance debate. The following text presents a summary of the issues discussed and the ‘Action Items'' agreed upon by the Expert Group at the ‘Life Insurance, Risk Stratification, and Personalized Medicine Symposium''.  相似文献   
92.
5F‐PY‐PICA and 5F‐PY‐PINACA are pyrrolidinyl 1‐(5‐fluoropentyl)ind (az)ole‐3‐carboxamides identified in 2015 as putative synthetic cannabinoid receptor agonist (SCRA) new psychoactive substances (NPS). 5F‐PY‐PICA, 5F‐PY‐PINACA, and analogs featuring variation of the 1‐alkyl substituent or contraction, expansion, or scission of the pyrrolidine ring were synthesized and characterized by nuclear magnetic resonance (NMR) spectroscopy and liquid chromatography–quadrupole time‐of‐flight–mass spectrometry (LC–QTOF–MS). In competitive binding experiments against HEK293 cells expressing human cannabinoid receptor type 1 (hCB1) or type 2 (hCB2), all analogs showed minimal affinity for CB1 (pKi < 5), although several demonstrated moderate CB2 binding (pKi 5.45–6.99). In fluorescence‐based membrane potential assays using AtT20‐hCB1 or ‐hCB2 cells, none of the compounds (at 10 μM) produced an effect >50% of the classical cannabinoid agonist CP55,940 (at 1 μM) at hCB1, although several showed slightly higher relative efficacy at hCB2. Expansion of the pyrrolidine ring of 5F‐PY‐PICA to an azepane ( 8 ) conferred the greatest hCB2 affinity (pKi 6.99) and activity (pEC50 7.54, Emax 72%) within the series. Unlike other SCRA NPS evaluated in vivo using radio biotelemetry, 5F‐PY‐PICA and 5F‐PY‐PINACA did not produce cannabimimetic effects (hypothermia, bradycardia) in mice at doses up to 10 mg/kg.  相似文献   
93.
94.
This study compared the staining potential of two experimental amine fluoride/stannous fluoride mouth rinses (A and B), a phenolic/essential oil rinse (C) and a negative control, water, rinse (D). The study was a single centre, randomized, single-blind, four treatment crossover study design among healthy participants. Prior to each study period, participants received a dental prophylaxis. On the Monday of each period, subjects suspended oral hygiene, and under supervision, rinsed with the allocated mouth rinse immediately followed by a warm black tea solution at hourly intervals eight times a day for 4?days. On Friday, the area and intensity of staining on the teeth, the primary outcome measure and dorsum of tongue were assessed. This regimen was repeated for all the three subsequent treatment periods. Rinse B produced less stain than rinse A, but the difference was not significant (p?=?0.20). Rinse B produced significantly more stain than rinse C (p?<?0.05) and D (p?<?0.001). For tongue staining, rinse B produced significantly more staining than D (p?<?0.01) but not A or C. Overall, all test rinses produced more staining than placebo with an overall pattern for more staining with stannous formulations. Individuals using stannous or phenolic/essential oil mouth rinse formulations should be advised of the possible staining side effect and that this can be easily removed by a professional dental cleaning.  相似文献   
95.
Classification systems and associated terminology are inherently slow in reflecting rapidly unfolding scientific discoveries in the mechanism and presentation of diseases. Misleading concepts, which often have historical value only, may become entrenched in the literature, leading to confusion and inaccurate communication. The purpose of this communication is to stimulate discussion and debate on inappropriate terminology associated with fibro-osseous disease that continues to be perpetuated in the literature. Use of the terms "cementum," "aggressive," "active," "gigantiform," and "maturation" are questioned, and the criteria applied to the interpretation of secondary changes in fibro-osseous lesions critically are evaluated.  相似文献   
96.
97.
98.
Objectives: There is a growing need for evaluation of the results of mental health services and clinical treatment in older people, but evidence for effectiveness is limited in Greece. The Health of the Nations Outcome Scales for Elderly People (HoNOS65+) are promising instruments for the assessment of mental, physical and social health in older persons. They have been translated into the Greek language but have not been validated. The aim was to assess the inter-rater reliability, intraclass correlation, concurrent validity, internal consistency and sensitivity to change of HoNOS65+ in a Greek sample of older people with mental health problems.

Method: Two samples, one of inpatients in a psychiatric hospital and the other of older people living in the community were used. In order to test the extent to which the HoNOS65+ were sensitive to change the first sample was reassessed after two months and the second after three months. For each participant HoNOS65+ were completed by two independent raters, and the clinician rated blindly each participant on the Stockton Geriatric Rating Scale and a scale which measured behavioural, physical, cognitive and emotional status.

Results: In both groups (inpatients n?=?50, community n?=?65), the inter-rater reliability, intraclass correlation and concurrent validity were high while internal consistency of the scales taken together was low. At reassessment in 98 participants, HoNOS65+ showed changes comparable to clinician ratings.

Conclusion: The Greek version of HoNOS65+ can achieve high levels of reliability, validity and sensitivity to change for measuring outcomes in older people with mental health problems.  相似文献   
99.
Vitamin D is made in the skin using ultraviolet radiation of specific low wavelength, 290–315 nm (UVB). For many parts of the world there is a period when there is insufficient intensity of UVB to make vitamin D, which is reflected by a clear seasonal variation in vitamin D status. Sun avoidance practices, melanin in pigmented skin, and sun protection creams (sunscreen), if used properly, can dramatically reduce vitamin D synthesis. Few foods naturally contain vitamin D, although some countries fortify foods with vitamin D. Regulatory mechanisms in the skin mean there is no danger of vitamin D toxicity through sunlight synthesis. Although oral vitamin D is potentially toxic with high-dose supplements, there is a wide safety margin. Long-term safety data covering a range of potential adverse outcomes are limited.  相似文献   
100.
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