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   65684篇
  免费   4892篇
  国内免费   395篇
耳鼻咽喉   904篇
儿科学   1385篇
妇产科学   1040篇
基础医学   10092篇
口腔科学   1475篇
临床医学   6490篇
内科学   13545篇
皮肤病学   1814篇
神经病学   5973篇
特种医学   3024篇
外国民族医学   11篇
外科学   8671篇
综合类   574篇
现状与发展   3篇
一般理论   38篇
预防医学   4195篇
眼科学   1226篇
药学   5283篇
中国医学   519篇
肿瘤学   4709篇
  2023年   517篇
  2022年   1231篇
  2021年   2058篇
  2020年   1258篇
  2019年   1698篇
  2018年   2014篇
  2017年   1603篇
  2016年   2063篇
  2015年   2513篇
  2014年   2953篇
  2013年   3582篇
  2012年   5382篇
  2011年   5282篇
  2010年   3096篇
  2009年   2497篇
  2008年   3784篇
  2007年   3735篇
  2006年   3422篇
  2005年   3145篇
  2004年   2802篇
  2003年   2394篇
  2002年   2139篇
  2001年   1014篇
  2000年   999篇
  1999年   866篇
  1998年   480篇
  1997年   380篇
  1996年   339篇
  1995年   293篇
  1994年   261篇
  1993年   211篇
  1992年   430篇
  1991年   426篇
  1990年   414篇
  1989年   338篇
  1988年   335篇
  1987年   349篇
  1986年   361篇
  1985年   330篇
  1984年   264篇
  1983年   213篇
  1982年   150篇
  1979年   289篇
  1978年   197篇
  1977年   164篇
  1975年   171篇
  1974年   157篇
  1973年   161篇
  1972年   158篇
  1971年   168篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
The Taser® eXtended Range Electronic Projectile (XREP®) is a wireless conducted electrical weapon (CEW) designed to incapacitate a person from a larger distance. The aim of this study was to analyze the ballistic injury potential of the XREP. Twenty rounds were fired from the Taser®X12 TM shotgun into ballistic soap covered with artificial skin and clothing at different shooting distances (1–25 m). One shot was fired at pig skin at a shooting distance of 10 m. The average projectile velocity was 67.0 m/s. The kinetic energy levels on impact varied from 28–52 J. Depending on the intermediate target, the projectiles penetrated up to 4.2 cm into the ballistic soap. On impact the nose assembly did not separate from the chassis, and no electrical activation was registered. Upon impact, a skin penetration of the XREP cannot be excluded. However, it is very unlikely at shooting distances of 10 m or more. Clothing and a high elasticity limit of the target body area can significantly reduce the penetration risk on impact.  相似文献   
993.
994.
Abstract

To increase healing rate of tympanic membrane (TM) perforations, patching procedure has been commonly conducted. Biocompatible, biodegradable patching materials which is not limited across cultures is needed. The authors evaluated the effectiveness of novel transparent duck’s feet collagen film (DCF) patch in acute traumatic TM perforation. This procedure was compared with spontaneous healing and paper patching. Cell proliferation features were observed in paper and DCF patches. Forty-eight TMs of 24 rats were used for animal experiment, perforations were made on each TMs, and divided into three groups according to treatment modality. Sixteen were spontaneously healed, 16 were paper patched and 16 were DCF patched. The gross and histological healing results were analyzed. Both paper and DCF patch showed no cytotoxicity, but cell proliferations were more active in DCF than paper in early stage. In animal study, the healing of TM perforations were completed within 14 days in all three groups, but found to be faster in DCF patch group than paper patch or spontaneous healing group. The DCF patches were transparent and size of DCF patches were gradually decreased, so there were no need to remove the DCF patches to check the wound status or after the completion of healing. According to this result, authors concluded that DCF patch is transparent, biocompatible and biodegradable material, and can induce fast healing in acute traumatic TM perforations.  相似文献   
995.
Magnetic resonance phase contrast angiography (MRA) is the gold standard for blood flow evaluation. Spectral Doppler ultrasound (SDU) is the first clinical choice, although the method is angle dependent. Vector flow imaging (VFI) is an angle-independent ultrasound method. The aim of the study was to compare VFI- and SDU-estimated peak systolic velocities (PSV) of the common carotid artery (CCA) with PSV obtained by MRA. Furthermore, intra- and inter-observer agreement was determined. MRA estimates were significantly different from SDU estimates (left CCA: p?<?0.001, right CCA: p?<?0.001), but not from VFI estimates (left CCA: p?=?0.28, right CCA: p?=?0.18). VFI measured lower PSV in both CCAs compared with SDU (p?<?0.001) with improved precision (VFI: left: 24%, right: 18%; SDU: left 38%, right: 23%). Intra- and inter-observer agreement was almost perfect for VFI and SDU (inter-observer correlation coefficient: VFI 0.88, SDU 0.91; intra-observer correlation coefficient: VFI 0.96, SDU 0.97). VFI is more accurate than SDU in evaluating PSV compared with MRA.  相似文献   
996.
HDAC inhibitors have been reported to produce antidepressant and pro-cognitive effects in animal models, however, poor brain bioavailability or lack of isoform selectivity of current probes has limited our understanding of their mode of action. We report the characterization of novel pyrimidine hydroxyl amide small molecule inhibitors of HDAC6, brain bioavailable upon systemic administration. We show that two compounds in this family, ACY-738 and ACY-775, inhibit HDAC6 with low nanomolar potency and a selectivity of 60- to 1500-fold over class I HDACs. In contrast to tubastatin A, a reference HDAC6 inhibitor with similar potency and peripheral activity, but more limited brain bioavailability, ACY-738 and ACY-775 induce dramatic increases in α-tubulin acetylation in brain and stimulate mouse exploratory behaviors in novel, but not familiar environments. Interestingly, despite a lack of detectable effect on histone acetylation, we show that ACY-738 and ACY-775 share the antidepressant-like properties of other HDAC inhibitors, such as SAHA and MS-275, in the tail suspension test and social defeat paradigm. These effects of ACY-738 and ACY-775 are directly attributable to the inhibition of HDAC6 expressed centrally, as they are fully abrogated in mice with a neural-specific loss of function of HDAC6. Furthermore, administered in combination, a behaviorally inactive dose of ACY-738 markedly potentiates the anti-immobility activity of a subactive dose of the selective serotonin reuptake inhibitor citalopram. Our results validate new isoform-selective probes for in vivo pharmacological studies of HDAC6 in the CNS and reinforce the viability of this HDAC isoform as a potential target for antidepressant development.  相似文献   
997.
998.
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