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   60314篇
  免费   4593篇
  国内免费   260篇
耳鼻咽喉   556篇
儿科学   1857篇
妇产科学   1296篇
基础医学   8502篇
口腔科学   1017篇
临床医学   6350篇
内科学   12717篇
皮肤病学   1267篇
神经病学   6436篇
特种医学   1873篇
外国民族医学   11篇
外科学   7232篇
综合类   583篇
一般理论   67篇
预防医学   6024篇
眼科学   1009篇
药学   4054篇
  1篇
中国医学   132篇
肿瘤学   4183篇
  2023年   629篇
  2022年   976篇
  2021年   2164篇
  2020年   1417篇
  2019年   1881篇
  2018年   2127篇
  2017年   1654篇
  2016年   1823篇
  2015年   1922篇
  2014年   2567篇
  2013年   3122篇
  2012年   4771篇
  2011年   4894篇
  2010年   2667篇
  2009年   2229篇
  2008年   3484篇
  2007年   3564篇
  2006年   3357篇
  2005年   3000篇
  2004年   2744篇
  2003年   2317篇
  2002年   2103篇
  2001年   705篇
  2000年   686篇
  1999年   638篇
  1998年   439篇
  1997年   347篇
  1996年   324篇
  1995年   299篇
  1994年   239篇
  1993年   200篇
  1992年   361篇
  1991年   335篇
  1990年   335篇
  1989年   270篇
  1988年   285篇
  1987年   301篇
  1986年   308篇
  1985年   287篇
  1984年   256篇
  1983年   192篇
  1982年   151篇
  1981年   151篇
  1980年   139篇
  1979年   247篇
  1978年   173篇
  1977年   148篇
  1976年   130篇
  1974年   143篇
  1973年   150篇
排序方式: 共有10000条查询结果,搜索用时 213 毫秒
101.
The present article presents the future of clinical psychology board certification. With the increasing specialization in the field of professional psychology and the generic nature of state licensure, clinical psychology as a specialty will develop into a specialty area in a similar fashion as have specialties in medicine. A brief history of board certification in professional psychology by the American Board of Professional Psychology is reviewed and the process of becoming board certified in either clinical psychology or clinical child and adolescent psychology is discussed.  相似文献   
102.
103.
104.
SEVERAL SCIENTIFIC AND GENERAL MEDICAL JOURNALS publish full-length articles on their Web sites and abridged versions in their print journals. We surveyed a stratified random sample of BMJ readers and authors to elicit their preferred format for the abridged print version. Each participant received a research paper abridged in 3 different formats: conventional abridged version, journalistic version and enhanced-abstract version. Overall, 45% (95% confidence interval [CI] 42%–48%) of the respondents said they liked the conventional version most, 31% (95% CI 28%–34%) preferred the journalistic version and 25% (95% CI 22%–27%) preferred the enhanced-abstract version. Twenty-eight percent (95% CI 25%–32%) indicated that use of the journalistic format for abridged articles would very likely stop them from submitting papers to BMJ, and 13% (95% CI 11%–16%) said the use of the enhanced-abstract version would stop them from submitting to BMJ. Publishers of general medical journals who publish shortened articles should consider that authors and readers prefer a more conventional style of abridged papers.  相似文献   
105.
BACKGROUND CONTEXT: The injection of various solutions aimed at producing a sclerosing effect has been used to treat soft tissues injuries (eg, inguinal hernia) for more than 100 years. In the 1930s, this treatment approach was applied to injured joints in an attempt to stimulate connective tissue repair. Although several studies have been published about this method of treatment for various orthopedic and spinal indications (termed prolotherapy), its use remains controversial. PURPOSE: To conduct a critical review of the literature on prolotherapy for spinal pain. STUDY DESIGN/SETTING: Critical review of the literature. METHODS: Computerized medical literature databases (Medline, CINAHL, Mantis, Cochrane Central Register of Controlled Trials) were searched to uncover all published information about the use of sclerosing injections in humans with spinal pain disorders. Search results were reviewed for relevance, and information was abstracted from full-text articles. RESULTS: Our search uncovered almost 200 reference materials in various media related to prolotherapy, including 31 clinical studies related to spinal pain. There were 26 observational cohorts and 5 randomized clinical trials (RCTs). Indications in these studies were low back pain (22), neck pain (3), cervical headaches (3) and dorsal or thoracic pain (3). A total of 20 sclerosing solutions were used in these studies; the most common was a mixture of dextrose 12.5%, glycerin 12.5%, phenol 1.25% and lidocaine 0.25%. Wide variations were found in treatment protocols, such as dose, number of treatments and use of adjunct therapies. Most cohort studies were only of moderate quality and varied greatly in the substances injected and the use of co-interventions. Most clinical studies reported positive results such as decreased pain or disability, although differences between treatment and control groups did not always reach statistical significance. Commonly reported adverse reactions to this treatment include temporary postinjection pain and stiffness. A handful of more serious adverse events were reported in the 1950s and 1960s with stronger or unknown solutions. CONCLUSION: Prolotherapy describes a variety of treatment approaches rather than a specific protocol. Results from clinical studies published to date indicate that it may be effective at reducing spinal pain. Great variation was found in the injection and treatment protocols used in these studies that preclude definite conclusions. Future research should focus on those solutions and protocols that are most commonly used in clinical practice and have been used in trials reporting effectiveness to help determine which patients, if any, are most likely to benefit from this treatment.  相似文献   
106.
Background: The cardiotoxic mechanism of local anesthetics may include interruption of cardiac sympathetic reflexes. The authors undertook this investigation to determine if clinically relevant concentrations of bupivacaine and levobupivacaine interfere with exocytotic norepinephrine release from cardiac sympathetic nerve endings.

Methods: Rat atria were prepared for measurements of twitch contractile force and 3[H]-norepinephrine release. After nerve endings were loaded with 3[H]-norepinephrine, the tissue was electrically stimulated in 5-min episodes during 10 10-min sampling periods. After each period, a sample of bath fluid was analyzed for radioactivity and 3[H]-norepinephrine release was expressed as a fraction of tissue counts. Atria were exposed to buffer alone during sampling periods 1 and 2 (S1 and S2). Control atria received saline (100 [mu]l each, n = 6 atria) in S3-S10. Experimental groups (n = 6 per group) received either bupivacaine or levobupivacaine at concentrations (in [mu]M) of 5 (S3-S4), 10 (S5-S6), 30 (S7-S8), and 100 (S9-S10).

Results: Bupivacaine and levobupivacaine decreased stimulation-evoked fractional 3[H]-norepinephrine release with inhibitory concentration 50% values of 5.1 +/- 0.5 and 6.1 +/- 1.3 [mu]m. The inhibitory effect of both local anesthetics (~70%) approached that of tetrodotoxin. Local anesthetics abolished the twitch contractions of atria with inhibitory concentration 50% values of 12.6 +/- 5.0 [mu]m (bupivacaine) and 15.7 +/- 3.9 [mu]m (levobupivacaine). In separate experiments, tetrodotoxin inhibited twitch contractile force by only 30%.  相似文献   

107.
108.
109.
The brains of pathogen-free autoimmune MRL/lpr, NZBWF1 and NZB mice were examined for central nervous system (CNS) inflammation in premoribund 8-week-old animals and at ages when active systemic lupus erythematosus (SLE) was present. CNS inflammation was observed only in MRL/lpr mice. Immunohistochemical studies of brains from young MRL/lpr mice found that infiltrates were composed primarily of CD4+ cells. Older MRL/lpr mice (22 and 26 weeks of age) had CD4+ cells predominantly, but CD8+ and B220+ cells were also present. Perivascular leakage of IgG was a prominent and unexpected finding in the MRL/lpr model. Congenic MRL/+ mice with late-onset autoimmunity had no inflammatory cells in brain tissue, and there was no perivascular staining with IgG or albumin. Our findings suggest that MRL/lpr mice are a useful model for studies of lupus-associated CNS inflammatory disease, and perivascular leakage may be a primary mechanism for entry of IgG into the brain.  相似文献   
110.
Lipid monolayer states and their relationships to bilayers.   总被引:11,自引:2,他引:9  
Uncommon methods of formation and analysis of lipid monolayers have enabled the recognition of several monolayer states and the identification of that in which molecular organization corresponds closely to that of the bilayer. Monolayers were formed by continuously adding a solution of phospholipid [dimyristoyl phosphatidylcholine in hexane/ethanol, 9:1 (vol/vol)] to the air/water interface of a constant-area trough. This procedure generates unconventional surface pressure (pi)-surface concentration (gamma) isotherms, which for liquid-crystalline monolayers consist of straight lines with three prominent intersections, two of which are not apparent in conventional pi-A isotherms. The regions of linear change of pi are explicable in terms of the area dependence of alkyl chain entropy. The two breaks at lower pi delimit states in which both chains lie parallel to the surface. The third occurs at collapse, which corresponds to a true equilibrium for unstressed liposomes. Mechanical and thermodynamic properties of bilayers, particularly phase-transition parameters, correspond closely to those of monolayers with which they are in equilibrium.  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