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   26481篇
  免费   2545篇
  国内免费   87篇
耳鼻咽喉   269篇
儿科学   611篇
妇产科学   367篇
基础医学   3132篇
口腔科学   865篇
临床医学   3499篇
内科学   5740篇
皮肤病学   647篇
神经病学   1908篇
特种医学   1252篇
外科学   3644篇
综合类   471篇
一般理论   24篇
预防医学   2942篇
眼科学   363篇
药学   2002篇
中国医学   23篇
肿瘤学   1354篇
  2021年   370篇
  2020年   242篇
  2019年   359篇
  2018年   421篇
  2017年   302篇
  2016年   373篇
  2015年   430篇
  2014年   613篇
  2013年   935篇
  2012年   1154篇
  2011年   1162篇
  2010年   679篇
  2009年   646篇
  2008年   1077篇
  2007年   1107篇
  2006年   1123篇
  2005年   1126篇
  2004年   1055篇
  2003年   985篇
  2002年   981篇
  2001年   997篇
  2000年   1023篇
  1999年   869篇
  1998年   360篇
  1997年   341篇
  1996年   315篇
  1995年   305篇
  1994年   262篇
  1993年   256篇
  1992年   623篇
  1991年   640篇
  1990年   614篇
  1989年   557篇
  1988年   515篇
  1987年   512篇
  1986年   504篇
  1985年   502篇
  1984年   352篇
  1983年   306篇
  1982年   241篇
  1981年   235篇
  1980年   172篇
  1979年   331篇
  1978年   243篇
  1977年   215篇
  1976年   177篇
  1975年   175篇
  1974年   214篇
  1973年   204篇
  1971年   193篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
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   
4.
This study explored the relationship between active mediation, exposure to Daniel Tiger’s Neighborhood, and key indicators of preschoolers’ social and emotional development. One hundred and twenty-seven children aged 2–6 either watched or did not watch 10 episodes of Daniel Tiger’s Neighborhood over a two-week period. Results revealed that preschoolers who watched the program exhibited higher levels of empathy, self-efficacy, and emotion recognition when their regular TV-watching experiences are frequently accompanied by active mediation. This was especially true for younger preschoolers and preschoolers from low-income families. Implications for policy-makers, parents, producers of prosocial programming, and educators are discussed.  相似文献   
5.
6.
The hepatitis C virus (HCV) is a pandemic human pathogen posing a substantial health and economic burden in both developing and developed countries. Controlling the spread of HCV through behavioural prevention strategies has met with limited success and vaccine development remains slow. The development of antiviral therapeutic agents has also been challenging, primarily due to the lack of efficient cell culture and animal models for all HCV genotypes, as well as the large genetic diversity between HCV strains. On the other hand, the use of interferon-α-based treatments in combination with the guanosine analogue, ribavirin, achieved limited success, and widespread use of these therapies has been hampered by prevalent side effects. For more than a decade, the HCV RNA-dependent RNA polymerase (RdRp) has been targeted for antiviral development. Direct acting antivirals (DAA) have been identified which bind to one of at least six RdRp inhibitor-binding sites, and are now becoming a mainstay of highly effective and well tolerated antiviral treatment for HCV infection. Here we review the different classes of RdRp inhibitors and their mode of action against HCV. Furthermore, the mechanism of antiviral resistance to each class is described, including naturally occurring resistance-associated variants (RAVs) in different viral strains and genotypes. Finally, we review the impact of these RAVs on treatment outcomes with the newly developed regimens.  相似文献   
7.
8.
9.
Annals of Surgical Oncology - The role of sentinel lymph node biopsy (SLNB) when ductal carcinoma in situ with microinvasion (DCISM) is identified on core biopsy is unclear. Our aim was to assess...  相似文献   
10.
We used the dual capability of hyperpolarized 129Xe for spectroscopy and imaging to develop new measures of xenon diffusing capacity in the rat lung that (analogously to the diffusing capacity of carbon monoxide or DLCO) are calculated as a product of total lung volume and gas transfer rate constants divided by the pressure gradient. Under conditions of known constant pressure breath-hold, the volume is measured by hyperpolarized 129Xe MRI, and the transfer rate is measured by dynamic spectroscopy. The new quantities (xenon diffusing capacity in lung parenchyma (DLXeLP)), xenon diffusing capacity in RBCs (DLXeRBC), and total lung xenon diffusing capacity (DLXe)) were measured in six normal rats and six rats with lung inflammation induced by instillation of fungal spores of Stachybotrys chartarum. DLXeLP, DLXeRBC, and DLXe were 56 +/- 10 ml/min/mmHg, 64 +/- 35 ml/min/mmHg, and 29 +/- 9 ml/min/mmHg, respectively, for normal rats, and 27 +/- 9 ml/min/mmHg, 42 +/- 27 ml/min/mmHg, and 16 +/- 7 ml/min/mmHg, respectively, for diseased rats. Lung volumes and gas transfer times for LP (TtrLP) were 16 +/- 2 ml and 22 +/- 3 ms, respectively, for normal rats and 12 +/- 2 ml and 35 +/- 8 ms, respectively, for diseased rats. Xenon diffusing capacities may be useful for measuring changes in gas exchange associated with inflammation and other lung diseases.  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