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   1771篇
  免费   105篇
  国内免费   22篇
耳鼻咽喉   30篇
儿科学   156篇
妇产科学   17篇
基础医学   186篇
口腔科学   47篇
临床医学   192篇
内科学   393篇
皮肤病学   23篇
神经病学   38篇
特种医学   475篇
外科学   115篇
综合类   37篇
预防医学   52篇
眼科学   13篇
药学   58篇
中国医学   5篇
肿瘤学   61篇
  2022年   4篇
  2021年   7篇
  2020年   10篇
  2019年   9篇
  2018年   17篇
  2017年   11篇
  2016年   24篇
  2015年   31篇
  2014年   30篇
  2013年   58篇
  2012年   28篇
  2011年   29篇
  2010年   81篇
  2009年   61篇
  2008年   43篇
  2007年   29篇
  2006年   39篇
  2005年   29篇
  2004年   28篇
  2003年   19篇
  2002年   28篇
  2001年   21篇
  2000年   30篇
  1999年   30篇
  1998年   137篇
  1997年   120篇
  1996年   129篇
  1995年   93篇
  1994年   76篇
  1993年   84篇
  1992年   23篇
  1991年   21篇
  1990年   19篇
  1989年   59篇
  1988年   45篇
  1987年   50篇
  1986年   49篇
  1985年   47篇
  1984年   24篇
  1983年   32篇
  1982年   34篇
  1981年   21篇
  1980年   36篇
  1979年   16篇
  1978年   15篇
  1977年   17篇
  1976年   24篇
  1975年   24篇
  1971年   2篇
  1966年   2篇
排序方式: 共有1898条查询结果,搜索用时 15 毫秒
1.
2.
Pediatric knee MR imaging: pattern of injuries in the immature skeleton   总被引:3,自引:0,他引:3  
  相似文献   
3.
4.
We report an adult female with a rare giant choledochal cyst. The patient presented following a normal pregnancy with the classical triad of an abdominal mass associated with jaundice and right upper quadrant abdominal pain. The cyst was excised using an intramural technique and biliary reconstruction achieved with a Roux-en-Y hepaticojejunostomy. Our patient has remained well with no evidence of malignancy over a 12 year review period. The aetiology and current management of this condition are discussed.  相似文献   
5.
6.
Na+ dependence of in vitro pancreatic amylase release   总被引:1,自引:0,他引:1  
  相似文献   
7.
The objective was to test the hypothesis that the optimal cryoprotective agent for cryopreservation of human spermatozoa would be a solute for which cells have the highest plasma membrane permeability, resulting in the least amount of volume excursion during its addition and removal. To test this hypothesis, theoretical simulations were performed using membrane permeability coefficients to predict optimal procedures for the addition and removal of a cryoprotectant. Simulations were performed using data from four different cryoprotectants: (i) glycerol, (ii) dimethyl sulphoxide, (iii) propylene glycol and (iv) ethylene glycol. Thermodynamic formulations were applied to determine approaches for the addition and removal of 1 M and 2 M final concentrations of cryoprotectant, allowing the spermatozoa to maintain a cell volume within their osmotic tolerance limits. Based on these data, ethylene glycol was predicted to be optimal for minimizing volume excursions among the solutes evaluated. These predictions were then experimentally tested using glycerol as the control cryoprotectant and ethylene glycol as the experimental cryoprotectant. The results indicate that there was a higher (P < 0.05) recovery of motile spermatozoa after cryopreservation when using 1 M ethylene glycol than with 1 M glycerol, supporting the hypothesis that use of the cryoprotectant for which the cell has the highest permeability will result in higher cell survival.   相似文献   
8.
A total of 447 cervical or vaginal specimens were inoculated in parallel onto peptone-starch-dextrose (PSD) and Columbia colistin (10 mg/ml)-nalidixic acid (15 mug/ml) (CNA) agar and were incubated for 48 h at 35 degrees C in an atmosphere with 2 to 10% CO2. One hundred (22.4%) of the cultures were positive for Haemophilus vaginalis. Forty-eight of the isolates were recovered from both PSD and Columbia CNA agar, five from PSD only, and 47 from Columbia CNA agar only (P less than 0.001). On Columbia CNA agar, 76 of the isolates were detected after 24 h of incubation, and the remainder were detected within 4 days of incubation.  相似文献   
9.
Chervin RD  Archbold KH 《Sleep》2001,24(3):313-320
STUDY OBJECTIVES: Children with sleep-disordered breathing (SDB) or periodic leg movements during sleep (PLMS) often have hyperactive behavior that improves when the sleep disorder is treated. Some children with SDB also have PLMS. To determine what polysomnographic features of SDB might be associated with hyperactive behavior, we studied behavior, SDB, and PLMS in a series of patients. DESIGN: Prospective and observational. SETTING: University-based sleep disorders laboratory. SUBJECTS: Children (n=113) aged 2 to 18 years, referred for suspected SDB. INTERVENTIONS: Parents completed the hyperactivity index of the Connors' Parental Rating Scale, and results were converted to age-adjusted t-scores. Children underwent laboratory-based polysomnography, with esophageal pressure monitoring when requested (n=19) by referring physicians. RESULTS: Children with SDB (n=59) showed high hyperactivity scores (mean 59.5+/-18.3 SD, 95% C.I. [54.7, 64.2]) but these scores were no higher than those of children without SDB (59.0+/-15.1, [54.8, 63.1]). Hyperactivity showed no significant associations with the rate of apneas and hypopneas, minimum oxygen saturation, or most negative esophageal pressure (p>0.10), but was associated with the presence of 5 or more PLMS per hour (p=0.02). The rate of PLMS showed a linear association with hyperactivity among those subjects with SDB (p = 0.002), but no association among those subjects without SDB (p = 0.64). CONCLUSIONS: These findings suggest that hyperactive behavior is common among children referred for suspected SDB, regardless of the presence or severity of SDB. Current observations cannot prove causality, but they are consistent with the hypothesis that PLMS may contribute to hyperactivity and SDB may act as an effect modifier.  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