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   578813篇
  免费   32506篇
  国内免费   3520篇
耳鼻咽喉   7022篇
儿科学   17743篇
妇产科学   13148篇
基础医学   97030篇
口腔科学   13292篇
临床医学   55358篇
内科学   101540篇
皮肤病学   12414篇
神经病学   35912篇
特种医学   21228篇
外国民族医学   72篇
外科学   81198篇
综合类   18223篇
现状与发展   20篇
一般理论   112篇
预防医学   43433篇
眼科学   13131篇
药学   47153篇
  56篇
中国医学   4932篇
肿瘤学   31822篇
  2021年   5920篇
  2019年   5190篇
  2018年   7069篇
  2017年   5639篇
  2016年   6153篇
  2015年   7409篇
  2014年   9794篇
  2013年   13413篇
  2012年   19708篇
  2011年   21744篇
  2010年   13453篇
  2009年   11819篇
  2008年   18939篇
  2007年   20598篇
  2006年   19912篇
  2005年   18843篇
  2004年   17700篇
  2003年   16924篇
  2002年   16229篇
  2001年   23496篇
  2000年   23906篇
  1999年   19568篇
  1998年   5608篇
  1997年   4723篇
  1996年   4671篇
  1995年   4388篇
  1992年   14583篇
  1991年   15981篇
  1990年   16083篇
  1989年   15749篇
  1988年   14411篇
  1987年   14317篇
  1986年   13266篇
  1985年   12759篇
  1984年   9449篇
  1983年   8051篇
  1982年   4205篇
  1979年   8961篇
  1978年   6404篇
  1977年   5166篇
  1976年   5515篇
  1975年   6626篇
  1974年   7433篇
  1973年   7187篇
  1972年   6618篇
  1971年   6320篇
  1970年   5904篇
  1969年   5479篇
  1968年   5168篇
  1967年   4627篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Pharmaceutical Chemistry Journal - An HPLC-MS method for simultaneous quantitative determination of a novel gestagenic pharmaceutical and two of its metabolites in rat and rabbit blood sera was...  相似文献   
2.
3.
4.
5.
目的对不同季铵化程度(DQ)的N-三甲基壳聚糖(TMC)促进阿昔洛韦(ACV)滴眼液眼部滞留性进行考察。方法将浓度为0.5%,DQ分别为20%、40%及60%的TMC(TMC20,TMC40,TMC60)加入ACV滴眼液中;以同浓度壳聚糖(CS)ACV滴眼液为阳性对照,以普通ACV滴眼液为阴性对照,选用家兔为实验动物,采用悬挂泡技术和束缚泡技术进行离体眼球表面接触角及解吸附动力学进行研究,同时在各种ACV滴眼液中分别加入0.05%的荧光素钠为示踪剂,在体研究各种ACV滴眼液在家兔眼部的滞留性。结果与普通ACV滴眼液相比,含CS及TMC的滴眼液在角膜表面的接触角明显降低,解吸时间及在体滞留时间明显延长(P<0.05);与同浓度的CS ACV阳性对照相比,TMC20促进滞留作用较弱,而TMC40作用差异无显著性(P>0.05),而TMC60的作用明显较强(P<0.05)结论 TMC可显著增加ACV的眼部滞留性,且与其DQ呈正相关。  相似文献   
6.
Three‐dimensional (3D) printing technology, virtual reality, and augmented reality technology have been used to help surgeons to complete complex total hip arthroplasty, while their respective shortcomings limit their further application. With the development of technology, mixed reality (MR) technology has been applied to improve the success rate of complicated hip arthroplasty because of its unique advantages. We presented a case of a 59‐year‐old man with an intertrochanteric fracture in the left femur, who had received a prior left hip fusion. After admission to our hospital, a left total hip arthroplasty was performed on the patient using a combination of MR technology and 3D printing technology. Before surgery, 3D reconstruction of a certain bony landmark exposed in the surgical area was first performed. Then a veneer part was designed according to the bony landmark and connected to a reference registration landmark outside the body through a connecting rod. After that, the series of parts were made into a holistic reference registration instrument using 3D printing technology, and the patient's data for bone and surrounding tissue, along with digital 3D information of the reference registration instrument, were imported into the head‐mounted display (HMD). During the operation, the disinfected reference registration instrument was installed on the selected bony landmark, and then the automatic real‐time registration was realized by HMD through recognizing the registration landmark on the reference registration instrument, whereby the patient's virtual bone and other anatomical structures were quickly and accurately superimposed on the real body of the patient. To the best of our knowledge, this is the first report to use MR combined with 3D printing technology in total hip arthroplasty.  相似文献   
7.
8.
Evidence continues to grow on potential environmental health hazards associated with engineered nanomaterials (ENMs). While the geno- and cytotoxic effects of ENMs have been investigated, their potential to target the epigenome remains largely unknown. The aim of this study is two-fold: 1) determining whether or not industry relevant ENMs can affect the epigenome in vivo and 2) validating a recently developed in vitro epigenetic screening platform for inhaled ENMs. Laser printer-emitted engineered nanoparticles (PEPs) released from nano-enabled toners during consumer use and copper oxide (CuO) were chosen since these particles induced significant epigenetic changes in a recent in vitro companion study. In this study, the epigenetic alterations in lung tissue, alveolar macrophages and peripheral blood from intratracheally instilled mice were evaluated. The methylation of global DNA and transposable elements (TEs), the expression of the DNA methylation machinery and TEs, in addition to general toxicological effects in the lung were assessed. CuO exhibited higher cell-damaging potential to the lung, while PEPs showed a greater ability to target the epigenome. Alterations in the methylation status of global DNA and TEs, and expression of TEs and DNA machinery in mouse lung were observed after exposure to CuO and PEPs. Additionally, epigenetic changes were detected in the peripheral blood after PEPs exposure. Altogether, CuO and PEPs can induce epigenetic alterations in a mouse experimental model, which in turn confirms that the recently developed in vitro epigenetic platform using macrophage and epithelial cell lines can be successfully utilized in the epigenetic screening of ENMs.  相似文献   
9.
孙淑荣  董玲 《医学综述》2015,(2):257-259
妊娠妇女随着孕周的增加,其本身及胎儿代谢产物逐渐增多,加之循环血容量增加,使肾脏总体负荷加重,容易并发肾损害。妊娠期高血压疾病是妊娠期特有的疾病,其病理生理变化为全身小血管痉挛、内皮损伤及局部缺血;肾脏最先受累。严重的肾损害会导致较高的母儿患病率和病死率,而肾脏损害存在无症状阶段,通过筛查才能发现相对早期的肾损害。探索妊娠期高血压疾病早期肾损害敏感性指标,可早发现、早干预,从而减少不良产科结局。  相似文献   
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