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   40605篇
  免费   1971篇
  国内免费   277篇
耳鼻咽喉   346篇
儿科学   1238篇
妇产科学   936篇
基础医学   4811篇
口腔科学   1198篇
临床医学   2960篇
内科学   10719篇
皮肤病学   621篇
神经病学   3835篇
特种医学   1690篇
外国民族医学   3篇
外科学   6157篇
综合类   136篇
一般理论   12篇
预防医学   1961篇
眼科学   490篇
药学   2228篇
中国医学   69篇
肿瘤学   3443篇
  2023年   289篇
  2022年   582篇
  2021年   1244篇
  2020年   688篇
  2019年   995篇
  2018年   1305篇
  2017年   885篇
  2016年   1070篇
  2015年   1180篇
  2014年   1622篇
  2013年   1986篇
  2012年   3180篇
  2011年   3092篇
  2010年   1844篇
  2009年   1609篇
  2008年   2773篇
  2007年   2624篇
  2006年   2627篇
  2005年   2432篇
  2004年   2230篇
  2003年   2021篇
  2002年   1940篇
  2001年   317篇
  2000年   245篇
  1999年   350篇
  1998年   354篇
  1997年   297篇
  1996年   262篇
  1995年   268篇
  1994年   214篇
  1993年   216篇
  1992年   174篇
  1991年   142篇
  1990年   160篇
  1989年   126篇
  1988年   118篇
  1987年   94篇
  1986年   123篇
  1985年   90篇
  1984年   130篇
  1983年   91篇
  1982年   106篇
  1981年   80篇
  1980年   85篇
  1979年   56篇
  1978年   68篇
  1977年   43篇
  1976年   40篇
  1973年   38篇
  1972年   38篇
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
991.
ObjectiveAdvanced life support (ALS) knowledge and skills decrease in as little as three months, but only a few ALS providers actually attend retraining courses. We assess the effectiveness of a 3D serious game as a new tool for frequent ALS retraining.MethodsWe developed a 3D serious game for scenario-based ALS retraining. The serious game, called EMSAVE, was designed to promote self-correction while playing. We organized a retraining course in which 40 ALS providers played two cardiac arrest scenarios with EMSAVE and took a test with 38 multiple-choice questions before and after playing. We administered the same test again 3 months later to evaluate retention. Participants also rated EMSAVE and the overall retraining experience.ResultsAfter using EMSAVE, the number of correct answers per participant increased by 4.8 (95%CI +3.4, +6.2, p < 0.001) and all but one participant improved. After 3 months, despite an expected decrease in ALS knowledge and skills (?1.9 correct answers, 95%CI ?0.6, ?3.3, p < 0.01), there was a significant retention benefit (+2.9 correct answers per participant, 95%CI +1.5, +4.2, p < 0.001). Moreover, all but one participant regarded EMSAVE as a valuable tool to refresh ALS knowledge and skills, and 85% of participants were also willing to devote 1 h/month to retrain with the serious game.ConclusionsA 3D serious game for scenario-based retraining proved effective to retrain in ALS and supported retention of acquired knowledge and skills at 3 months. EMSAVE also positively engaged and motivated participants.  相似文献   
992.
The carbon–carbon double bond of arylidene acetones and chalcones can be selectively reduced with benzeneselenol generated in situ by reacting O-(tert-butyl) Se-phenyl selenocarbonate with hydrochloric acid in ethanol. This mild, metal-free and experimentally simple reduction procedure displays considerable functional-group compatibility, products are obtained in good to excellent yields, and the use of toxic Se/CO mixture and NaSeH, or the smelly and air-sensitive benzeneselenol, is avoided.

The carbon–carbon double bond of arylidene acetones and chalcones can be selectively reduced with benzeneselenol generated in situ by reacting O-(tert-butyl) Se-phenyl selenocarbonate with hydrochloric acid in ethanol.  相似文献   
993.
Clinical Oral Investigations - This study aimed to develop a porous chitosan–calcium–aluminate scaffold (CH-AlCa) in combination with a bioactive dosage of 1α,25-dihydroxyvitamin...  相似文献   
994.
Clinical Oral Investigations - To compare the clinical and histological response of supracrestal periodontal tissues to subgingival composite restorations versus natural root surfaces In 29...  相似文献   
995.
996.
The International Journal of Cardiovascular Imaging - Patients with non-ischaemic systolic heart failure (HF) and left bundle branch block (LBBB) can display a wide or narrow pattern (WP/NP) of the...  相似文献   
997.
The International Journal of Cardiovascular Imaging - Previous studies using conventional echocardiographic measurements have reported subclinical left ventricular (LV) diastolic abnormalities in...  相似文献   
998.
BackgroundNeurosteroids affect the balance between neuroexcitation and neuroinhibition but have been little studied in migraine. We compared the serum levels of pregnenolone sulfate, pregnanolone and estradiol in women with menstrually-related migraine and controls and analysed if a correlation existed between the levels of the three hormones and history of migraine and age.MethodsThirty women (mean age ± SD: 33.5 ± 7.1) with menstrually-related migraine (MM group) and 30 aged- matched controls (mean age ± SD: 30.9 ± 7.9) participated in the exploratory study. Pregnenolone sulfate and pregnanolone serum levels were analysed by liquid chromatography-tandem mass spectrometry, while estradiol levels by enzyme-linked immunosorbent assay.ResultsSerum levels of pregnenolone sulfate and pregnanolone were significantly lower in the MM group than in controls (pregnenolone sulfate: P = 0.0328; pregnanolone: P = 0.0271, Student’s t-test), while estradiol levels were similar. In MM group, pregnenolone sulfate serum levels were negatively correlated with history of migraine (R2 = 0.1369; P = 0.0482) and age (R2 = 0.2826, P = 0.0025) while pregnenolone sulfate levels were not age-related in the control group (R2 = 0.04436, P = 0.4337, linear regression analysis).ConclusionLow levels of both pregnanolone, a positive allosteric modulator of the GABAA receptor, and pregnenolone sulfate, a positive allosteric modulator of the NMDA receptor, involved in memory and learning, could contribute either to headache pain or the cognitive dysfunctions reported in migraine patients. Overall, our results agree with the hypothesis that migraine is a disorder associated with a loss of neurohormonal integrity, thus supporting the therapeutic potential of restoring low neurosteroid levels in migraine treatment.Supplementary InformationThe online version contains supplementary material available at 10.1186/s10194-021-01231-9.  相似文献   
999.
1000.
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