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   21954篇
  免费   1646篇
  国内免费   268篇
耳鼻咽喉   364篇
儿科学   532篇
妇产科学   553篇
基础医学   3234篇
口腔科学   370篇
临床医学   1747篇
内科学   4460篇
皮肤病学   523篇
神经病学   1652篇
特种医学   1132篇
外科学   3389篇
综合类   627篇
一般理论   9篇
预防医学   850篇
眼科学   484篇
药学   1531篇
  1篇
中国医学   205篇
肿瘤学   2205篇
  2023年   173篇
  2022年   105篇
  2021年   654篇
  2020年   435篇
  2019年   555篇
  2018年   649篇
  2017年   521篇
  2016年   709篇
  2015年   922篇
  2014年   1048篇
  2013年   1192篇
  2012年   1858篇
  2011年   1863篇
  2010年   1138篇
  2009年   933篇
  2008年   1286篇
  2007年   1214篇
  2006年   1155篇
  2005年   1092篇
  2004年   984篇
  2003年   845篇
  2002年   760篇
  2001年   565篇
  2000年   449篇
  1999年   390篇
  1998年   144篇
  1997年   131篇
  1996年   97篇
  1995年   95篇
  1994年   74篇
  1993年   61篇
  1992年   172篇
  1991年   165篇
  1990年   175篇
  1989年   176篇
  1988年   138篇
  1987年   160篇
  1986年   114篇
  1985年   100篇
  1984年   59篇
  1983年   49篇
  1981年   36篇
  1980年   30篇
  1979年   56篇
  1978年   45篇
  1977年   37篇
  1976年   31篇
  1975年   26篇
  1973年   27篇
  1971年   23篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Direct peroral cholangioscopy (POC) using an ultra‐slim upper endoscope is one modality of POC for intraductal endoscopic evaluation and treatment of the bile duct. Choledochoduodenostomy (CDS) is one modality of biliary bypass surgery that provides a new route to the bile duct. We carried out direct POC using an ultra‐slim upper endoscope without the use of accessories in 10 patients (four sump syndromes, three bile duct strictures and three intrahepatic duct stones) previously undergoing surgical CDS. Direct POC was successful in all patients. The use of an intraductal balloon catheter was required in one patient for advancement of the endoscope into the bile duct. Distal bile ducts with sump syndromes were cleared using baskets and water irrigation under direct POC. Cholangiocarcinoma was diagnosed in one patient with hilar bile duct stricture after cholangioscopic evaluation and a targeting forceps biopsy under direct POC. Intrahepatic duct stones were successfully extracted after intraductal fragmentation under direct POC. Oozing bleeding occurred during intraductal lithotripsy but stopped spontaneously. Direct POC using an ultra‐slim upper endoscope without the assistance of accessories can easily be carried out in patients undergoing CDS.  相似文献   
2.
3.
4.
5.
6.
7.
8.
Sometimes the clinical differentiation between verruca plana (VP) and VP‐like seborrheic keratosis (SK) could be challenged. However, there have been no studies on this issue to date. The aim of this study was to elucidate clinical and dermoscopic differences between these two diseases, and also to suggest a diagnostic algorithm of VP and VP‐like SK without skin biopsy. The patients who had lesions clinically considered as VP or VP‐like SK were the target of our study. We took clinical and dermoscopic photos with informed consent and conducted a questionnaire. All patients had their diagnoses confirmed by biopsy. Thirty‐three patients were enrolled in our study. Seventeen patients were finally diagnosed with VP (51.5%) and 16 patients with VP‐like SK (48.5%). In clinical findings, VP‐like SK showed significantly more scattered distribution than VP (P = 0.039), which exhibited more clustered or grouped distribution (P = 0.039). In dermoscopic findings, brain‐like appearance was more commonly observed in VP‐like SK (P = 0.003) whereas VP showed more red dots or globular vessels (P = 0.017) and even‐colored light brown to yellow patch (P < 0.001). Sex, onset age, the size of each lesion, location, color and shape showed no significant differences between them (P > 0.05). Based on our results, we suggest a diagnostic algorithm using Koebner's phenomenon, dermoscopic findings, distribution of each lesion and biopsy for multiple VP‐like lesions in adults, and we think it will be a very useful diagnostic tool in daily clinical dermatological practice.  相似文献   
9.
10.
Phytonutrients extracted from natural resources are receiving much attention among researchers due to their highly antioxidative characteristics which prevent several degenerative diseases including cardiovascular diseases and cancers. These nutraceutical compounds can be used in food, pharmaceutical and cosmetic products as natural antioxidants, preservatives, colourants and functional foods. Huge volume of food wastes are generated from the processing industry and these low-value food residues are rich in various phytonutrients worth recovering. This approach of valorisation reduces the generation of food wastes and is cost-effective considering the cheap feedstock, reduced waste management expenses and high market value of extracted compounds. In light of the health and safety risks posed by commonly used organic extraction solvents derived from the petrochemical industry, there is a need to recover the phytonutrients using green, sustainable and efficient solvents that are safe for human consumption. This work discusses ethyl lactate as a safe, green, efficient and potentially cheap solvent to recover phytonutrients from fruit and vegetable by-products. Ethyl lactate is compared with other organic solvents commonly used from the aspects of safety, environmental impacts and efficiency. Current challenges when employing ethyl lactate are also discussed.  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