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   1809篇
  免费   165篇
  国内免费   29篇
耳鼻咽喉   58篇
儿科学   62篇
妇产科学   33篇
基础医学   203篇
口腔科学   52篇
临床医学   207篇
内科学   325篇
皮肤病学   24篇
神经病学   113篇
特种医学   101篇
外科学   319篇
综合类   82篇
预防医学   158篇
眼科学   18篇
药学   129篇
中国医学   2篇
肿瘤学   117篇
  2021年   24篇
  2019年   17篇
  2018年   13篇
  2016年   21篇
  2015年   29篇
  2014年   23篇
  2013年   42篇
  2012年   71篇
  2011年   70篇
  2010年   51篇
  2009年   46篇
  2008年   64篇
  2007年   80篇
  2006年   92篇
  2005年   70篇
  2004年   73篇
  2003年   64篇
  2002年   48篇
  2001年   51篇
  2000年   71篇
  1999年   47篇
  1998年   48篇
  1997年   46篇
  1996年   39篇
  1995年   35篇
  1994年   33篇
  1993年   27篇
  1992年   50篇
  1991年   32篇
  1990年   37篇
  1989年   40篇
  1988年   35篇
  1987年   39篇
  1986年   36篇
  1985年   39篇
  1984年   25篇
  1983年   25篇
  1982年   18篇
  1981年   22篇
  1979年   22篇
  1978年   24篇
  1977年   17篇
  1976年   26篇
  1975年   17篇
  1974年   19篇
  1973年   19篇
  1972年   13篇
  1970年   16篇
  1969年   16篇
  1968年   14篇
排序方式: 共有2003条查询结果,搜索用时 15 毫秒
31.
用体内外实验模型,研究了新维A类化合物4-乙酰胺苯基维A酸酯(4-APR)对肿瘤侵袭、转移的抑制作用。4-APR 43.3mg·kg-1po即能减少小鼠Lewis肺癌的自发性肺转移瘤数。半体内实验证明4-APR10-5mol·L-1和10-6mol·L-1对B16-F10癌细胞的人工肺转移瘤数分别抑制67.9%和36.6%。体外实验显示,4-APR对B16-F10细胞侵袭重组基底膜的抑制率分别为54.2%和41.9%。  相似文献   
32.
33.
Contingency management (i.e. rewarding people, often with money, for achieving their recovery goals) is backed by decades of empirical support yet remains highly underutilized. Rewards are rarely used in real-world clinical practice due to a number of concerns, including most notably, the apparent lack of innovation, as well as moral, philosophical, ethical, and economic concerns, and even federal rules meant to prevent illegal inducements in health care. Still, other opponents argue that some patients will try to "game" the system by simply doing whatever it takes to earn monetary rewards. This paper provides a succinct, up-to-date overview of the current evidence base for contingency management for opioid use disorder. Common barriers and solutions to implementation, as well as implications for future research and clinical practice are discussed. Although important, greater uptake of contingency management interventions is about more than legislation and regulations; it’s about recognizing stigma, shaping attitudes, and increasing awareness. Provider involvement in advocacy efforts at all levels and collaboration involving academic–industry partnerships is necessary to advance the burgeoning digital health care space and improve outcomes for people with opioid use disorder.

Key Messages

  • Contingency management is highly effective but highly underutilized.
  • Low uptake is largely attributed to a lack of innovation and moral, ethical, and economic concerns, among other barriers.
  • Technology-enabled solutions and academic–industry partnerships are critical to advance opioid use disorder care.
  相似文献   
34.
Purpose : To describe strategies used by tutors teaching adults with learning disabilities to use desktop virtual environments and to investigate their effectiveness by examining changes over time in tutor and learner behaviour. Method : Twenty adults with learning disabilities spent 12 sessions with one of four non-disabled tutors learning to use desktop virtual environments designed to teach independent living skills. Sessions were recorded on videotape, categories of behaviour were described and tapes analysed for frequency of tutor behaviours and goals achieved by learners. Results : Tutor strategies were described in terms of whether they aimed to help the learner master the interaction devices or to navigate and achieve goals in the virtual environments and how directive they were. There were some differences between tutors but this did not relate to whether tutors were experienced users themselves of the environments or were initially unfamiliar with them. Goal achievement was maintained at a constant level while help with the interaction devices and specific information about the environment decreased over repeated sessions. Rates of non-specific information did not change. Conclusions : Pretraining with the interaction devices would free both tutor and learner to concentrate on achieving goals in the environments. Much of the specific help given by the tutor could be incorporated into the software.  相似文献   
35.
36.
37.
Antibody responses of two doses of a bivalent influenza vaccine containing A/Victoria/75 (A/Vic/75) and A/New Jersey/76 (A/NJ/76) viral antigens were studied in 22 children receiving maintenance chemotherapy for acute lymphoblastic leukemia (ALL), 16 children no longer receiving therapy for ALL, and 50 sibling controls. Before immunization, the three groups showed no difference in titer of antibody to either antigen. After the first immunization, children off therapy showed significantly higher titers to A/NJ/76 than did either sibling controls of children receiving therapy (P less than 0.01). After the second immunization, children off therapy showed significantly higher antibody titers to both antigens than did children receiving therapy or controls (P less than 0.01 for both A/NJ/76 and A/Vic/75). Antibody titers of children receiving therapy were not significantly different from those of controls. A year later, there were no significant differences in antibody titers among the groups. Thus, children with ALL who are receiving chemotherapy respond normally to two doses of influenza vaccine, whereas children off therapy manifest abnormally high titers of antibody to both influenza virus antigens.  相似文献   
38.
In 34 patients with chronic lymphatic leukaemia (CLL) the lymphocytes have been separated and sized using a C1000 Channelyzer. The modal volume and the volume range of the populations have been obtained and related to clinical stage and mouse red blood cell (MRBC) rosetting capacity. Over 1 year's observation with several estimations per patient there was no convincing drift towards increase in modal volume with deteriorating clinical status. The cell size of the CLL populations could vary from time to time in the same patient. The MRBC rosetting capacity varied greatly between estimations. The findings suggest that in CLL there is an oscillation in cell size in a given patient when tested at intervals.  相似文献   
39.
Stroke affects primarily aged and co-morbid people, aspects not properly considered to date. Since angiogenesis/vasculogenesis are key processes for stroke recovery, we purposed to determine how different co-morbidities affect the outcome and angiogenesis/vasculogenesis, using a rodent model of metabolic syndrome, and by dynamic enhanced-contrast imaging (DCE-MRI) to assess its non-invasive potential to determine these processes. Twenty/twenty-two month-old corpulent (JCR:LA-Cp/Cp), a model of metabolic syndrome and lean rats were used. After inducing the experimental ischemia by transient MCAO, angiogenesis was analyzed by histology, vasculogenesis by determination of endothelial progenitor cells in peripheral blood by flow cytometry and evaluating their pro-angiogenic properties in culture and the vascular function by DCE-MRI at 3, 7 and 28 days after tMCAO. Our results show an increased infarct volume, BBB damage and an impaired outcome in corpulent rats compared with their lean counterparts. Corpulent rats also displayed worse post-stroke angiogenesis/vasculogenesis, outcome that translated in an impaired vascular function determined by DCE-MRI. These data confirm that outcome and angiogenesis/vasculogenesis induced by stroke in old rats are negatively affected by the co-morbidities present in the corpulent genotype and also that DCE-MRI might be a technique useful for the non-invasive evaluation of vascular function and angiogenesis processes.  相似文献   
40.
The secret is comprised in three words – work, finish, publish.’Michael FaradayThere are many reasons doctors want to publish their work. For most at an early stage in their career, this may be to add a line to their curriculum vitae and advance their careers but for academics, publishing is an expectation. Many will believe they have something important to say, and wish to provoke debate and discussion; others wish to share knowledge and experiences, which in medicine can lead to a satisfying change in clinical practice. All serve to register one’s idea and educate others. However, for some, the reason is as basic as money. As we celebrate the 350th anniversary of the first academic publication, perhaps we have come full circle when it comes to why people publish?Publishing is a flourishing business. There were approximately 28,100 active scholarly peer-reviewed journals in mid-2012, collectively publishing about 1.8–1.9 million articles per year. The number of articles published each year and the number of journals have both grown steadily for more than two centuries, by about 3% and 3.5% per year respectively.1 Journals have a responsibility to refine and define information and act as a scientific filter. Many of us will receive daily invitations in our email inbox from eclectic and new journals that are likely to take anything – is the filter now too porous? But this industry is like any other commercial activity and the supply still far outstrips the demand. Perhaps the internet revolution has merely fuelled our hunger to publish more?The launch of this exciting and innovative series about publishing coincides with the 350th celebration of the publication of the first academic journal. In the age of social media, the first question is ‘What are journals for?’, which Simon Rallison sets out to answer. Simon is Director of Publications at the Physiological Society, and was previously a journal publisher with Earthscan, Springer and Blackwell.Writing is hard work and, through this series, I hope the reader will get some useful insight into this service industry for academia.Jyoti ShahCommissioning EditorIn an age of the internet and social media, why are we still using (admittedly with refinements and improvements) a form of publication dating from 1665? What exactly is a journal in the 21st century and what role does it have to perform? Surprisingly, the academic journal has not evolved since it was invented 350 years ago.1 The first issue of the Philosophical Transactions of the Royal Society was published in 1665, the brainchild of Henry Oldenburg and Robert Hooke. Since then, journals have digitised and now offer greater opportunity for research communication – but are authors taking advantage of what journals can offer? The academic and research community is generally very conservative about what it reads and how it views journals. There are, however, also frequent misunderstandings about the operation of journals.  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