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   4234篇
  免费   253篇
  国内免费   16篇
耳鼻咽喉   49篇
儿科学   259篇
妇产科学   93篇
基础医学   478篇
口腔科学   64篇
临床医学   329篇
内科学   714篇
皮肤病学   76篇
神经病学   187篇
特种医学   184篇
外科学   528篇
综合类   189篇
一般理论   2篇
预防医学   464篇
眼科学   192篇
药学   327篇
中国医学   17篇
肿瘤学   351篇
  2023年   27篇
  2022年   85篇
  2021年   131篇
  2020年   96篇
  2019年   93篇
  2018年   125篇
  2017年   69篇
  2016年   81篇
  2015年   104篇
  2014年   157篇
  2013年   194篇
  2012年   271篇
  2011年   321篇
  2010年   173篇
  2009年   156篇
  2008年   271篇
  2007年   237篇
  2006年   176篇
  2005年   188篇
  2004年   176篇
  2003年   150篇
  2002年   131篇
  2001年   74篇
  2000年   70篇
  1999年   64篇
  1998年   32篇
  1997年   26篇
  1995年   17篇
  1993年   17篇
  1992年   41篇
  1991年   34篇
  1990年   29篇
  1989年   40篇
  1988年   35篇
  1987年   29篇
  1986年   28篇
  1985年   31篇
  1984年   25篇
  1983年   20篇
  1982年   18篇
  1979年   42篇
  1978年   33篇
  1977年   19篇
  1974年   26篇
  1973年   21篇
  1972年   16篇
  1971年   20篇
  1970年   26篇
  1969年   15篇
  1966年   17篇
排序方式: 共有4503条查询结果,搜索用时 375 毫秒
1.
In light of the pharmacophoric structural requirements for achieving anticonvulsant activity, a series of N-(1-methyl-4-oxo-2-un/substituted-1,2-dihydroquinazolin-3[4H]-yl)benzamide (4a-g) and N-(1-methyl-4-oxo-2-un/substituted-1,2-dihydroquinazolin-3[4H]-yl)-2-phenylacetamide (4h-n) derivatives were synthesized in two steps starting from the reaction of N-methyl isatoic anhydride with the appropriate hydrazide and followed by condensation with the appropriate aldehyde. The anticonvulsant activities of the synthesized compounds were evaluated according to the anticonvulsant drug development (ADD) programme protocol. Among the synthesized compounds, 4n showed promising activity in both the maximal electroshock (MES) and pentylenetetrazole (PTZ) tests with median effective dose (ED50) values of 40.7 and 6 mg/kg, respectively. The six most promising derivatives, 4b , 4a , 4c , 4f , 4j , and 4i , showed very low ED50 values in the PTZ test (3.1, 4.96, 8.68, 9.89, 12, and 13.53 mg/kg, respectively). All the tested compounds showed no to low neurotoxicity in the rotarod test with a wide therapeutic index. Docking studies of compound 4n suggested that GABAA binding could be the mechanism of action of these derivatives. The in silico drug likeliness parameters indicated that none of the designed compounds violate Lipinski's rule of five and that they are able to cross the blood–brain barrier.
Hit, Lead & Candidate Discovery
  相似文献   
2.
3.
No study has yet been done to investigate the changes in endothelial cell size, perimeter, and density that may result from the warming of corneas in MK (McCarey-Kaufman) medium for specular microscopy. In the present investigation eye bank eyes were stored in MK medium at 4 degrees C and rewarmed daily for six days at 37 degrees C before specular photography of the endothelium was performed. These photographs were compared with wet mount preparations stained with trypan blue and alizarin red made from the same corneas and those stored without rewarming for six days. In addition all corneas were qualitatively analysed with the scanning electron microscope (SEM). The data from serial specular photography were insufficient to allow significant conclusions to be drawn about day to day changes in cell morphology. However, analysis of wet mount preparations revealed that cell density and perimeter varied significantly between those corneas rewarmed daily and those held in cold storage for six days. SEM studies showed an intact cell monolayer with cell loss along the folds of corneal endothelium. We therefore concluded that repeated rewarming at 37 degrees C of corneas stored in MK medium at 4 degrees has a deleterious effect on cell morphology and that folds induced by swelling of corneal tissue result in endothelial cell damage with some loss.  相似文献   
4.
Gall bladder perforation is a potentially life-threatening condition. Spontaneous perforation is infrequent and rarely seen in the absence of gallstones but gall bladder perforation is an occasional complication of typhoid fever. If such perforations are not treated in time, mortality rates are very high. We report a case of gall bladder perforation complicating typhoid fever following enteric perforation of the ileum necessitating sequential laparotomies during the same admission.  相似文献   
5.
Lymphoid clusters (LC) containing CD20-positive B cells in kidney allografts undergoing acute cellular rejection (ACR) have been identified in small studies as a prognostic factor for glucocorticoid resistance and graft loss. Allograft biopsies obtained during the first episode of ACR in 120 recipients were evaluated for LC, immunostained with CD20 antibody, and correlated with conventional histopathologic criteria, response to treatment and outcome. LC were found in 71 (59%) of the 120 biopsies. All contained CD20 positive B cells that accounted for 5-90% of the LC leukocyte content. The incidence of LC was highest in the patients who had no lymphoid depletion or had been treated with Thymoglobulin preconditioning (79% vs. 75%, respectively) compared to 37% in patients pretreated with Campath (p = 0.0001). Banff 1a/1b ACR were more frequent in the LC-positive than the LC-negative group (96% vs. 80%, respectively; p = 0.0051). With a posttransplant follow-up of 953 +/- 430 days, no significant differences were detected between LC-postitive and LC-negative groups in time to ACR, steroid resistance, serum creatinine and graft loss. CD20+LC did not portend glucocorticoid resistance or worse short to medium term outcomes. CD20+LC may represent a heterogenous collection in which there may be a small still to be fully defined unfavorable subgroup.  相似文献   
6.
A total of 168 strains of Salmonella were isolated in the Command Pathology Laboratory (WC) Delhi Cantt during the year 1990. Out of this, 143 were Salmonella typhi, 17 Salmonella paratyphi A, 7 Salmonella typhimurium and 1 Salmonella manhattan. The commonest phage type and biotype of Salmonella typhi was type E1 and type 1 respectively. The dominant biotype of Salmonella paratyphi A was type I. There was a very high degree of multidrug resistance of most of the strains. But all the strains were sensitive to ciprofloxacin and norfloxacin.  相似文献   
7.
8.
Introduction Hydatid cysts of the lung are quite frequent in our country. Some patients have additional cysts in the liver. Though most of the liver cysts remain asymptomatic for long time, but may be symptomatic with increasing size. Surgical removal is the treatment of choice for both lung & liver cysts. Aim of the study was to establish suitability of one stage surgery for pulmonary & hepatic hydatid cysts. Methods From 1996 through 2003 we operated on 216 pulmonary hydatid cysts, out of which 42 patients had hydatid cysts in the right lung as well as in the right lobe of liver. Right thoracotomy was done to remove the lung hydatids followed by phrenotomy to remove the liver cysts. Results Right thoracotomy was done in 42 patients having hydatid cysts of lung & liver. In 36 patients, cysts were removed, bronchial leaks were sutured & residual cavities were obliterated. Out of rest 6 patients, having dense adhesions or destruction of pulmonary parenchyma, 4 had segmentectomy & 2 had lobectomy. Right phrenotomy was then done with radial incision above the palpated liver cysts. Hydatid cyst was removed from liver. Cavity and remaining pericystic liver tissue was inverted with sutures. Water seal chest drain & subdiaphragmatic drain were placed. Post operative albendazole was continued for 3 months in the dose of 10–20 mg/kg with a gap of 2 weeks after each month. Post operative recovery was uneventful in most of the cases. However, air leak continued for almost 3 weeks in 4 patients & 3 months in one patient. There was no death. Conclusion Surgical management of pulmonary and hepatic hydatids with one stage right thoracotomy & phrenotomy is a suitable option. It avoids additional laparotomy and thereby additional cost & hospital stay. Results are quite satisfactory.  相似文献   
9.
10.
Poliomyelitis in India.   总被引:1,自引:0,他引:1  
R N Basu 《Indian pediatrics》1991,28(6):589-592
  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