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   36890篇
  免费   2668篇
  国内免费   161篇
耳鼻咽喉   281篇
儿科学   1085篇
妇产科学   730篇
基础医学   4597篇
口腔科学   647篇
临床医学   3573篇
内科学   8300篇
皮肤病学   569篇
神经病学   3843篇
特种医学   1173篇
外国民族医学   1篇
外科学   5217篇
综合类   557篇
一般理论   30篇
预防医学   3023篇
眼科学   738篇
药学   2617篇
  1篇
中国医学   55篇
肿瘤学   2682篇
  2023年   209篇
  2022年   285篇
  2021年   713篇
  2020年   481篇
  2019年   702篇
  2018年   809篇
  2017年   619篇
  2016年   674篇
  2015年   819篇
  2014年   1164篇
  2013年   1626篇
  2012年   2421篇
  2011年   2709篇
  2010年   1507篇
  2009年   1388篇
  2008年   2282篇
  2007年   2588篇
  2006年   2447篇
  2005年   2542篇
  2004年   2292篇
  2003年   2175篇
  2002年   2012篇
  2001年   338篇
  2000年   256篇
  1999年   392篇
  1998年   458篇
  1997年   343篇
  1996年   351篇
  1995年   288篇
  1994年   247篇
  1993年   278篇
  1992年   228篇
  1991年   223篇
  1990年   180篇
  1989年   165篇
  1988年   172篇
  1987年   154篇
  1986年   118篇
  1985年   180篇
  1984年   247篇
  1983年   206篇
  1982年   243篇
  1981年   250篇
  1980年   242篇
  1979年   116篇
  1978年   131篇
  1977年   128篇
  1976年   114篇
  1974年   92篇
  1973年   76篇
排序方式: 共有10000条查询结果,搜索用时 531 毫秒
21.
BACKGROUND: The 1997 National Asthma Education and Prevention Program (NAEPP) recommends a severity classification scheme to optimize the use of anti-inflammatory therapy for persistent asthma. Physician documentation of asthma severity is often used as a quality assurance measure. OBJECTIVE: To test the hypothesis that physician documentation of asthma severity is associated with appropriate use of anti-inflammatory therapy. DESIGN/METHODS: Setting: inner-city academic health center. First, we reviewed a consecutive sample of charts of scheduled pediatric patients. Then, we administered a structured parent survey regarding the child's asthma symptoms and current asthma therapy. We used NAEPP guidelines to classify patients' severity of asthma. The main outcome measure was appropriate use of anti-inflammatory therapy. Appropriate therapy was defined as: (1) mild persistent asthmatics using anti-inflammatory therapy, and (2) moderate-severe persistent asthmatics using inhaled steroids. Chart classification of asthma severity was compared with the NAEPP-applied classification. RESULTS: Of 784 charts, 214 (27%) were asthmatic. Of these, 176 (82%) were surveyed. The mean age was 7.4 years; 61% were males. Severity classification was documented in 77% of charts. Chart documentation differed significantly from survey classification for the same patients: (mild intermittent 54% vs. 40%, mild persistent 21% vs. 14%, moderate persistent 24% vs. 36%, severe persistent 1% vs. 10%; all p < .001). Correctly classified patients were more likely to be on appropriate therapy. CONCLUSIONS: Physicians underestimated the severity classification of asthmatic patients. Incorrect classification was associated with inappropriate asthma therapy. These findings have implications for the institution of asthma quality improvement programs.  相似文献   
22.
23.
Background The Retinal Thickness Analyser (RTA) is intended to detect glaucomatous changes as well as macular pathologies at the posterior pole. We determined the diagnostic accuracy for eyes with manifest glaucoma or macular diseases.Methods We examined 71 eyes with long-term, established eye conditions. Included were 28 eyes with glaucoma, 21 with different macular diseases and 22 normal eyes. All examinations were evaluated in a blind-test by RTA experts without any clinical information on the patients. After comparison of the RTA interpretation with the clinical diagnosis, we determined sensitivity, specificity, positive and negative predictive values.Results Of 71 examinations, 15 (21%) were not interpretable. If these results are excluded, the following diagnostic accuracy values were calculated for glaucoma and macular disorders respectively: sensitivity 75 and 59%, specificity 55 and 97%, positive predictive value 48 and 90% and negative predictive value 80 and 84%. These values were not significantly different when both eyes of each patient were included in the final analysis (n=133).Conclusion The diagnostic values of the RTA determined in this case control study were not satisfactory. However, no clinical information was used in the assessment. The extent to which additional clinical information increases the diagnostic value remains to be determined.  相似文献   
24.
25.
26.
The effects of an indirect dopamine-agonist, d-amphetamine, and a non-selective dopamine receptor antagonist, haloperidol, were investigated in normal male volunteers using a between-subjects double-blind design in a procedural learning task, thought mainly to involve unconscious/automatic learning. The results showed: (1) d-amphetamine facilitated response speed, whereas haloperidol inhibited it, in comparison to placebo; (2) the linear increase in procedural learning corresponded with pharmacological manipulation of degree of dopaminergic activity, i.e. subjects given haloperidol showed the least, and subjects given d-amphetamine the greatest, procedural learning. The implications of these findings are discussed in relation to investigation of abnormalities of procedural learning processes in schizophrenia. Received: 28 June 1996/Final version: 2 October 1996  相似文献   
27.
28.
29.
30.
Evidence has accumulated suggesting that the presence of calcium is critical for development of hippocampal long-term potentiation (LTP). However, there is a paucity of information about whether calcium's role in LTP is pre- or postsynaptic. In the present study, we examined the effectiveness of nitrendipine, verapamil, flunarizine and the benzodiazepine diazepam in: blocking voltage-dependent calcium channels; blocking synaptic transmission; and preventing development of LTP. Using the in vitro slice preparation, we obtained intracellular and extracellular recordings from guinea pig hippocampal CA1 pyramidal cells. At the cellular level, all 4 drugs were ineffective in blocking voltage-dependent calcium spikes (TTX resistant) and the calcium-dependent afterhyperpolarization. Verapamil and diazepam appeared to antagonize synaptic transmission, as reflected in smaller population spike amplitudes. Development of long-term potentiation was not affected by the presence of verapamil, flunarizine and diazepam. Nitrendipine appeared to reduce the percentage of slices exhibiting LTP; however, ethanol, the vehicle used to dissolve nitrendipine, was shown in separate experiments to reduce the percentage of slices exhibiting LTP. These results suggest that neither the organic calcium channel blockers--nitrendipine, verapamil, and flunarizine--nor micromolar concentrations of diazepam are potent blockers of extrasynaptic voltage-sensitive calcium channels in hippocampus. They thus cannot be used to demonstrate a specific pre- or postsynaptic calcium role in LTP.  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