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   999802篇
  免费   75276篇
  国内免费   2617篇
耳鼻咽喉   12986篇
儿科学   34502篇
妇产科学   28702篇
基础医学   145664篇
口腔科学   27747篇
临床医学   90381篇
内科学   194249篇
皮肤病学   22949篇
神经病学   79207篇
特种医学   38433篇
外国民族医学   305篇
外科学   149802篇
综合类   23747篇
一般理论   385篇
预防医学   77916篇
眼科学   22620篇
药学   72067篇
  3篇
中国医学   2038篇
肿瘤学   53992篇
  2018年   10569篇
  2017年   8248篇
  2016年   9392篇
  2015年   10611篇
  2014年   14434篇
  2013年   22045篇
  2012年   29097篇
  2011年   31007篇
  2010年   18564篇
  2009年   17464篇
  2008年   28941篇
  2007年   30667篇
  2006年   31195篇
  2005年   29771篇
  2004年   29110篇
  2003年   27968篇
  2002年   26999篇
  2001年   47045篇
  2000年   48195篇
  1999年   40378篇
  1998年   11181篇
  1997年   10100篇
  1996年   10164篇
  1995年   9780篇
  1994年   9093篇
  1993年   8484篇
  1992年   32253篇
  1991年   31461篇
  1990年   31010篇
  1989年   29877篇
  1988年   27171篇
  1987年   27327篇
  1986年   25437篇
  1985年   24604篇
  1984年   18401篇
  1983年   15521篇
  1982年   9293篇
  1981年   8382篇
  1979年   16862篇
  1978年   12223篇
  1977年   10320篇
  1976年   9759篇
  1975年   10183篇
  1974年   12322篇
  1973年   11848篇
  1972年   10886篇
  1971年   10116篇
  1970年   9382篇
  1969年   8732篇
  1968年   8109篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
Human multiple sip drinking was simulated by repeated, alternate application of a NaCl solution and a second liquid to the anterior portion of the tongue. Judged intensity of the NaCl solution remained constant during alternation with artificial saliva, increased during alternation with water, and decreased during alternation with an identical NaCl solution or with no second liquid. Relative change in concentration on the tongue may determine constancy, facilitation, or adaptation during drinking.  相似文献   
982.
983.
Results of three therapeutic modalities used for the treatment of a homogeneous series of patients with a Pouteau Colles fracture are analyzed. Orthopedic treatment provided deceiving results. Pinning was, on the contrary, very effective, intrafocal pinning with immediate mobilization of the wrist appearing perfectly effective. Few complications were reported in contrast to plastered immobilizations. Good results were obtained in 80% of cases and functional recovery was rapid, indicating that this method represents undoubted progress when compared with conventional therapies.  相似文献   
984.
985.
The response of the unattached 218Po activity size distribution to variations in H2O and SO2 concentration was investigated in a high-purity N2 atmosphere. Lognormal size distributions were reconstructed from screen diffusion battery data using a random search and optimization procedure. For relative humidities of 1% to 90%, SO2 concentrations of 0-6 ppm, and residence times of 38 s, median diameters of the unattached mode ranged from 0.50 (+/- 0.04) to 0.80 (+/- 0.06) nm, corresponding to diffusion coefficients of 0.1-0.05 cm2 s-1. Increases in water vapor concentration resulted in an enhanced rate of ion neutralization and suppression of ion cluster formation. Decreases in cluster diameter with increasing humidity were therefore observed. Addition of SO2 at constant relative humidity resulted in an initial increase in diameter, with a subsequent decrease. Geometric standard deviations averaged 1.05 (+/- 0.01) to 1.06 (+/- 0.01) in all cases, with the unattached fraction comprising 83% to 88% of the total distribution. Results suggest that increases in water vapor concentration enhance neutralization in the immediate vicinity of the recoil path through water radiolysis. Conversion of OH to H2OSO4 on addition of SO2 provides a binary condensable phase capable of clustering around the ion at low relative humidities, increasing particle size. High H2O and SO2 concentrations enhance neutralization through electron scavenging and subsequent ion collision near the end of the recoil path, decreasing the number of available cluster sites and suppressing cluster formation. This reduction is more significant than the increasing size of the stable ion cluster, with increasing H2O and H2SO4 concentrations as predicted by Raes, resulting in decreases in both median diameter and distribution spread.  相似文献   
986.
987.
In a prospective, randomized, single-masked, cross-over study, 18 patients with primary open-angle glaucoma were treated for one month with each of the following regimens: timolol 0.5% twice daily, timolol 0.5% plus dipivefrin 0.1% twice daily given ten minutes apart, and timolol 0.5% plus dipivefrin 0.1% given twice daily four hours apart. An eight-hour intraocular pressure curve was obtained before treatment and at the end of each monthly regimen. When added to timolol therapy, dipivefrin produced a small but statistically significant additional mean decrease in intraocular pressure. The difference in intraocular pressure reduction between the two regimens for combined timolol and dipivefrin therapy was not statistically significant.  相似文献   
988.
989.
Toscana virus was maintained in a laboratory colony of Phlebotomus perniciosus by vertical (transovarial) transmission for 13 consecutive generations over a 23-month period. No significant biological changes were noted in the virus after prolonged vertical passage in the sand flies, and transovarially infected females were able to transmit the agent by bite to susceptible animals. Chronic infection of Ph. perniciosus with Toscana virus had no apparent effect on the insects' rate of eclosion. In the absence of selection and with random matings, the virus infection rates in each subsequent generation of the colony decreased, suggesting that Toscana virus cannot be maintained in Ph. perniciosus by transovarial transmission alone. Alternative mechanisms for virus maintenance are discussed.  相似文献   
990.
The goals of this report are: 1) to review the number needed to treat (NNT) concept, which, although well established in many sectors of medicine, is still relatively new to the radiotherapy community; 2) to discuss several clinical radiotherapy examples illustrating the inherent advantages of the NNT approach; and 3) to discuss potential future roles of the NNT concept within radiotherapy.  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