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   1022472篇
  免费   77113篇
  国内免费   2680篇
耳鼻咽喉   13292篇
儿科学   35284篇
妇产科学   29024篇
基础医学   149869篇
口腔科学   28286篇
临床医学   92607篇
内科学   198663篇
皮肤病学   23552篇
神经病学   81171篇
特种医学   39344篇
外国民族医学   308篇
外科学   152949篇
综合类   23899篇
一般理论   399篇
预防医学   79556篇
眼科学   23037篇
药学   73612篇
  3篇
中国医学   2059篇
肿瘤学   55351篇
  2018年   10947篇
  2017年   8620篇
  2016年   9826篇
  2015年   11019篇
  2014年   15038篇
  2013年   22846篇
  2012年   30091篇
  2011年   31913篇
  2010年   19123篇
  2009年   18084篇
  2008年   29818篇
  2007年   31517篇
  2006年   31932篇
  2005年   30599篇
  2004年   29907篇
  2003年   28651篇
  2002年   27718篇
  2001年   47631篇
  2000年   48712篇
  1999年   40879篇
  1998年   11456篇
  1997年   10344篇
  1996年   10414篇
  1995年   9980篇
  1994年   9300篇
  1993年   8683篇
  1992年   32633篇
  1991年   31959篇
  1990年   31483篇
  1989年   30324篇
  1988年   27543篇
  1987年   27712篇
  1986年   25809篇
  1985年   25019篇
  1984年   18686篇
  1983年   15764篇
  1982年   9464篇
  1981年   8527篇
  1979年   17161篇
  1978年   12432篇
  1977年   10491篇
  1976年   9903篇
  1975年   10383篇
  1974年   12548篇
  1973年   12049篇
  1972年   11074篇
  1971年   10283篇
  1970年   9519篇
  1969年   8864篇
  1968年   8231篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Smoking is much more common among persons with behavioral health conditions (mental illnesses and/or substance use disorders). Persons with these disorders are more likely to die from smoking-related causes than any other reason. Studies have shown that stopping smoking can improve mental health function, as well as improve outcomes for substance use disorders. Yet, for a variety of reasons, smoking cessation has not been integrated into the treatment of behavioral health conditions, and in many instances tobacco use was not only condoned but encouraged. Beginning in 2007, the Smoking Cessation Leadership Center (SCLC) began engaging relevant agencies in an attempt to stimulate more vigorous smoking cessation activities. Partners included the federal Substance Abuse and Mental Health Services Administration, advocacy organizations such as the National Alliance on Mental Illness and Community Anti-Drug Coalitions of America, and clinical groups such as the American Psychiatric Nurses Association, the American Psychiatric Association, American Psychological Association, National Council on Behavioral Health, and National Association of State Mental Health Program Directors. A signature program featured 16 individual state summits involving agencies and groups from multiple sectors, all aiming to lower smoking rates in behavioral health populations. These activities mark an evolving culture change within behavioral health.  相似文献   
62.
63.
64.
65.
66.
Cardiovascular magnetic resonance imaging (CMR) permits accurate phenotyping of many cardiac diseases. CMR’s inherent advantages are its non‐invasive nature, lack of ionizing radiation and high accuracy and reproducibility. Furthermore, it is able to assess many aspects of cardiac anatomy, structure and function. Specifically, it can characterize myocardial tissue, myocardial function, myocardial mass, myocardial blood flow/perfusion, irreversible and reversible injury, all with a high degree of accuracy and reproducibility. Hence, CMR is a powerful tool in clinical and pre‐clinical research. In recent years there have been novel advances in CMR myocardial tissue characterization. Oxygenation‐sensitive CMR (OS‐CMR) is a novel non‐invasive, contrast independent technique that permits direct quantification of myocardial tissue oxygenation, both at rest and during stress. In this review, we will address the principles of the OS‐CMR technique, its recent advances and summarize the studies in the effects of oxygenation on cardiac diseases.  相似文献   
67.
Brain imaging is considered one of the most fruitful applications of radioisotope scanning. Rolipram, a selective phospodiesterase‐4 inhibitor, has been labeled using [125I] with chloramine‐T (Ch‐T) as an oxidizing agent. Factors, such as the amount of substrate, pH, the amount of oxidizing agent, temperature, and the reaction time, have been systematically studied to optimize the iodination process. In addition, bio‐distribution studies have indicated that the brain uptake of [125I]iodorolipram is 7.6 ± 0.33 injected dose/g organ at 10 minutes post‐injection, which cleared from the brain with time until it reaches 1.30 ± 0.17% at 1 hour post‐injection. Therefore, iodorolipram could be considered as a potential, new selective radiotracer for brain imaging.  相似文献   
68.
The spread of antimicrobial resistance challenges the empirical treatment of urinary tract infections (UTIs). Among others, nitrofurantoin is recommended for first-line treatment, but acceptance among clinicians is limited due to chronic nitrofurantoin-induced lung toxicity and insufficient coverage of Enterobacteriaceae other than Escherichia coli. Nitroxoline appears to be an alternative to nitrofurantoin owing to its favourable safety profile, however data on its current in vitro susceptibility are sparse. In this study, susceptibility to nitroxoline was tested against 3012 urinary clinical isolates (including multidrug-resistant bacteria and Candida spp.) by disk diffusion test and/or broth microdilution. At least 91% of all Gram-negatives (n?=?2000), Gram-positives (n?=?403) and yeasts (n?=?132) had inhibition zone diameters for nitroxoline ≥18?mm. Except for Pseudomonas aeruginosa, nitroxoline MIC90 values were ≤16?mg/L and were 2- to >16-fold lower compared with nitrofurantoin. In extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae and methicillin-resistant Staphylococcus aureus (MRSA), MIC90 values of nitroxoline were two-fold higher compared with non-ESBL-producing enterobacteria and methicillin-susceptible S. aureus (MSSA). The in vitro efficacies of nitroxoline and nitrofurantoin against ATCC strains of E. coli, Enterococcus faecalis and Proteus mirabilis were compared by time–kill curves in Mueller–Hinton broth and artificial urine. Nitroxoline was non-inferior against E. coli, P. mirabilis and E. faecalis in artificial urine. In conclusion, nitroxoline showed a broad antimicrobial spectrum, with inhibition zone diameters and MICs of nitroxoline well below the EUCAST breakpoint for E. coli for most organisms, and thus may also be a target for therapy of uncomplicated UTIs.  相似文献   
69.
70.
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