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   20697篇
  免费   1408篇
  国内免费   144篇
耳鼻咽喉   282篇
儿科学   492篇
妇产科学   350篇
基础医学   2733篇
口腔科学   477篇
临床医学   1978篇
内科学   3832篇
皮肤病学   210篇
神经病学   2439篇
特种医学   769篇
外国民族医学   1篇
外科学   2608篇
综合类   251篇
一般理论   14篇
预防医学   1995篇
眼科学   715篇
药学   1779篇
中国医学   47篇
肿瘤学   1277篇
  2023年   85篇
  2022年   157篇
  2021年   342篇
  2020年   200篇
  2019年   307篇
  2018年   407篇
  2017年   324篇
  2016年   321篇
  2015年   374篇
  2014年   578篇
  2013年   901篇
  2012年   1294篇
  2011年   1369篇
  2010年   732篇
  2009年   625篇
  2008年   1269篇
  2007年   1401篇
  2006年   1356篇
  2005年   1410篇
  2004年   1365篇
  2003年   1260篇
  2002年   1257篇
  2001年   234篇
  2000年   210篇
  1999年   260篇
  1998年   289篇
  1997年   273篇
  1996年   223篇
  1995年   254篇
  1994年   163篇
  1993年   209篇
  1992年   167篇
  1991年   147篇
  1990年   149篇
  1989年   150篇
  1988年   122篇
  1987年   134篇
  1986年   125篇
  1985年   149篇
  1984年   141篇
  1983年   135篇
  1982年   177篇
  1981年   193篇
  1980年   163篇
  1979年   104篇
  1978年   104篇
  1977年   121篇
  1976年   103篇
  1975年   65篇
  1974年   44篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Bowel diseases of prematurity, including necrotizing enterocolitis, are dreaded ailments of neonates. Early diagnosis is difficult, with clinical and radiographic findings often inconclusive. We present a novel use of contrast-enhanced ultrasound in detection of pediatric bowel disease. Early identification of compromised blood flow or an at-risk bowel can be quantitatively detected and monitored. This ability has implications for guidance of emerging therapies, allowing targeting of inflammation. These findings represent an advancement in detection of bowel disease in neonates.  相似文献   
3.
Since the 1990s, oral rabies vaccination (ORV) has been used successfully to halt the westward spread of the raccoon rabies virus (RV) variant from the eastern continental USA. Elimination of raccoon RV from the eastern USA has proven challenging across targeted raccoon (Procyon lotor) and striped skunk (Mephitis mephitis) populations impacted by raccoon RV. Field trial evaluations of the Ontario Rabies Vaccine Bait (ONRAB) were initiated to expand ORV products available to meet the rabies management goal of raccoon RV elimination. This study describes the continuation of a 2011 trial in West Virginia. Our objective was to evaluate raccoon and skunk response to ORV occurring in West Virginia for an additional two years (2012–2013) at 75 baits/km2 followed by three years (2014–2016) of evaluation at 300 baits/km2. We measured the change in rabies virus-neutralizing antibody (RVNA) seroprevalence in targeted wildlife populations by comparing levels pre- and post-ORV during each year of study. The increase in bait density from 75/km2 to 300/km2 corresponded to an increase in average post-ORV seroprevalence for raccoon and skunk populations. Raccoon population RVNA levels increased from 53% (300/565, 95% CI: 50–57%) to 82.0% (596/727, 95% CI: 79–85%) during this study, and skunk population RVNA levels increased from 11% (8/72, 95% CI: 6–20%) to 39% (51/130, 95% CI: 31–48%). The RVNA seroprevalence pre-ORV demonstrated an increasing trend across study years for both bait densities and species, indicating that multiple years of ORV may be necessary to achieve and maintain RVNA seroprevalence in target wildlife populations for the control and elimination of raccoon RV in the eastern USA.  相似文献   
4.
5.
ABSTRACT

Forensic DNA analysis is dependent on comparing the known and the unknown. Expand the number of known profiles, and the likelihood of a successful match increases. Forensic use of DNA is moving towards comparing samples of unknown origin with publicly available genetic data, such as the records held by genetic genealogy providers. Use of forensic genetic genealogy has yielded a number of recent high-profile successes but has raised ethical and privacy concerns. Navigating family trees is complex, even more so when combined with a comparison of genetic relationships. This intelligence-gathering process has led to occasional false leads, and its use also risks a public backlash, similar to concerns over Cambridge Analytica. A cautious approach to use of this technique is therefore warranted.  相似文献   
6.
7.
Over 100 mutations in the presenilin‐1 gene (PSEN1) have been shown to result in familial early onset Alzheimer disease (EOAD), but only a relatively few give rise to plaques with an appearance like cotton wool (CWP) and/or spastic paraparesis (SP). A family with EOAD, seizures and CWP was investigated by neuropathological study and DNA sequencing of the PSEN1 gene. Aβ was identified in leptomeningeal vessels and in cerebral plaques. A single point mutation, p.L420R (g.1508T > G) that gives rise to a missense mutation in the eighth transmembrane (TM8) domain of PS1 was identified in two affected members of the family. p.L420R (g.1508T > G) is the mutation responsible for EOAD, seizures and CWP without SP in this family.  相似文献   
8.
9.
10.
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