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   3279篇
  免费   263篇
  国内免费   21篇
耳鼻咽喉   52篇
儿科学   136篇
妇产科学   94篇
基础医学   394篇
口腔科学   93篇
临床医学   317篇
内科学   660篇
皮肤病学   87篇
神经病学   129篇
特种医学   230篇
外国民族医学   5篇
外科学   406篇
综合类   63篇
一般理论   1篇
预防医学   265篇
眼科学   74篇
药学   337篇
中国医学   13篇
肿瘤学   207篇
  2023年   47篇
  2022年   136篇
  2021年   205篇
  2020年   123篇
  2019年   151篇
  2018年   201篇
  2017年   127篇
  2016年   137篇
  2015年   124篇
  2014年   176篇
  2013年   242篇
  2012年   265篇
  2011年   253篇
  2010年   150篇
  2009年   99篇
  2008年   139篇
  2007年   123篇
  2006年   130篇
  2005年   135篇
  2004年   107篇
  2003年   88篇
  2002年   59篇
  2001年   26篇
  2000年   24篇
  1999年   43篇
  1998年   13篇
  1997年   10篇
  1996年   15篇
  1995年   7篇
  1994年   6篇
  1993年   5篇
  1992年   16篇
  1991年   23篇
  1990年   15篇
  1989年   14篇
  1988年   15篇
  1987年   8篇
  1986年   18篇
  1985年   13篇
  1984年   6篇
  1983年   7篇
  1982年   6篇
  1981年   7篇
  1980年   7篇
  1979年   7篇
  1978年   4篇
  1977年   4篇
  1976年   5篇
  1975年   5篇
  1974年   4篇
排序方式: 共有3563条查询结果,搜索用时 35 毫秒
41.
42.
43.
44.
A series of 1,2,4‐triazolo[1,5‐a]pyrimidine derivatives was designed, synthesized, and screened for their phosphodiesterase (PDE 4B) inhibitory activity and bronchodilation ability. Compound 7e showed 41.80% PDE 4B inhibition at 10 µM. Eight compounds were screened for their bronchodilator activity, where compounds 7f and 7e elicited promising bronchodilator activity with EC50 values of 18.6 and 57.1 µM, respectively, compared to theophylline (EC50 = 425 µM). Molecular docking at the PDE 4B active site revealed a binding mode and docking scores comparable to those of a reference ligand, consistent with their PDE 4B inhibition activity.  相似文献   
45.
46.
Magnesium alloys have been proposed as prospective degradable implant materials. To elucidate the complex interactions between the corroding implants and the tissue, magnesium implants were analyzed in a mouse model and the response was compared to that induced by Ti and by the resorbable polymer polyglactin, respectively. One month after implantation, distinct traces of corrosion were apparent but the magnesium implants were still intact, whereas resorbable polymeric wound suture implants were already fragmented. Analysis of magnesium implants 2 weeks after implantation by energy-dispersive X-ray spectroscopy indicated that magnesium, oxygen, calcium and phosphate were present at the implant surface. One month after implantation, the element composition of the outermost layer of the implant was indicative of tissue without detectable levels of magnesium, indicating a protective barrier function of this organic layer. In agreement with this notion, gene expression patterns in the surrounding tissue were highly similar for all implant materials investigated. However, high-resolution imaging using energy-filtered transmission electron microscopy revealed magnesium-containing microparticles in the tissue in the proximity of the implant. The release of such corrosion particles may contribute to the accumulation of calcium phosphate in the nearby tissue and to bone conductive activities of magnesium implants.  相似文献   
47.
A mixed case of chronic tracheal (syringeal) and pulmonary (lungs and air sacs) aspergillosis was diagnosed in an adult female gyrfalcon (Falco rusticolus). The bird presented with a 4-week history of severe dyspnea, exercise intolerance, depression and reduced appetite. Physical examination revealed slight emaciation. Hematological analysis showed leucocytosis, heterophilia, monocytosis, and thrombocytosis. Radiographic examination showed thickening of the air sac walls and increased radiopacity within the lung field. Caseous granulomatous lesions were observed during tracheoscopy and laparoscopy procedures. Cytological examination of specimens obtained from these lesions demonstrated Aspergillus species, which was isolated in culture and identified as Aspergillus flavus.  相似文献   
48.
Background: The main objective of the present study is to quantify doxycycline (DOX) release from β‐tricalcium phosphate (β‐TCP) after EDTA root surface treatment. Methods: Thirty systemically healthy patients with ≥1 paired contralateral interproximal intrabony defect ≥4 mm deep along with an interproximal probing depth ≥6 mm and clinical attachment level ≥4 mm were randomized into two groups. Group 1 (G1) consisted of sites treated with open flap debridement followed by placement of DOX blended with β‐TCP (DOX‐β‐TCP), whereas group 2 (G2) sites were treated with flap surgery followed by the placement of DOX blended with β‐TCP after EDTA etching of the exposed root surfaces (DOX‐β‐TCP + EDTA). Samples of gingival crevicular fluid (GCF) were obtained 1, 3, 7, 14, and 21 days after surgery. Quantitative measurements of DOX were taken with high‐performance liquid chromatography. Clinical evaluation and follow‐up for 6 months were performed. Results: At 21 days, the DOX‐β‐TCP + EDTA–treated group showed a 194.7 µg/mL value. The DOX‐β‐TCP + EDTA–treated group retained more DOX during the periods of 3, 7, 10, 14, and 21 days than the DOX‐β‐TCP–treated group. Six months after therapy, DOX‐β‐TCP + EDTA–treated sites showed more significant clinical improvements compared to DOX‐β‐TCP–treated sites (P ≤ 0.05). Conclusions: EDTA root surface etching enhances DOX availability in the GCF following its release from β‐TCP as a drug carrier.  相似文献   
49.
50.
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