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   2933篇
  免费   241篇
  国内免费   14篇
耳鼻咽喉   11篇
儿科学   143篇
妇产科学   29篇
基础医学   382篇
口腔科学   64篇
临床医学   291篇
内科学   672篇
皮肤病学   26篇
神经病学   185篇
特种医学   201篇
外科学   407篇
综合类   101篇
一般理论   1篇
预防医学   216篇
眼科学   18篇
药学   290篇
中国医学   7篇
肿瘤学   144篇
  2021年   38篇
  2019年   45篇
  2018年   42篇
  2017年   29篇
  2016年   54篇
  2015年   76篇
  2014年   65篇
  2013年   88篇
  2012年   121篇
  2011年   133篇
  2010年   81篇
  2009年   86篇
  2008年   120篇
  2007年   112篇
  2006年   107篇
  2005年   110篇
  2004年   82篇
  2003年   93篇
  2002年   85篇
  2001年   92篇
  2000年   93篇
  1999年   85篇
  1998年   41篇
  1997年   62篇
  1996年   43篇
  1995年   54篇
  1994年   48篇
  1993年   37篇
  1992年   68篇
  1991年   48篇
  1990年   56篇
  1989年   89篇
  1988年   69篇
  1987年   56篇
  1986年   53篇
  1985年   40篇
  1984年   37篇
  1983年   27篇
  1982年   31篇
  1981年   23篇
  1980年   24篇
  1977年   27篇
  1976年   22篇
  1974年   34篇
  1973年   32篇
  1972年   27篇
  1971年   26篇
  1970年   28篇
  1969年   23篇
  1967年   26篇
排序方式: 共有3188条查询结果,搜索用时 15 毫秒
11.
BACKGROUND. The incidence of infection increases with the prolonged use of central vascular catheters, but it is unclear whether changing catheters every three days, as some recommend, will reduce the rate of infection, It is also unclear whether it is safer to change a catheter over a guide wire or insert it at a new site. METHODS. We conducted a controlled trial in adult patients in intensive care units who required central venous or pulmonary-artery catheters for more than three days. Patients were assigned randomly to undergo one of four methods of catheter exchange: replacement every three days either by insertion at a new site (group 1) or by exchange over a guide wire (group 2), or replacement when clinically indicated either by insertion at a new site (group 3) or by exchange over a guide wire (group 4). RESULTS. Of the 160 patients, 5 percent had catheter-related bloodstream infections, 16 percent had catheters that became colonized, and 9 percent had major mechanical complications. The incidence rates (per 1000 days of catheter use) of bloodstream infection were 3 in group 1, 6 in group 2, 2 in group 3, and 3 in group 4; the incidence rates of mechanical complications were 14, 4, 8, and 3, respectively. Patients randomly assigned to guide-wire-assisted exchange were more likely to have bloodstream infection after the first three days of catheterization (6 percent vs. 0, P = 0.06). Insertions at new sites were associated with more mechanical complications (5 percent vs. 1 percent, P = 0.005). CONCLUSIONS. Routine replacement of central vascular catheters every three days does not prevent infection. Exchanging catheters with the use of a guide wire increases the risk of bloodstream infection, but replacement involving insertion of catheters at new sites increases the risk of mechanical complications.  相似文献   
12.
This study investigated the effect of providing clinicians with a report from a computer-assisted interview conducted prior to the clinical assessment of children referred to a mental health service. The results suggest that the availability of reports from computer-assisted interviews influenced the type of problems identified by clinicians and the services that they recommended to manage the children's problems. It is suggested that reports from computer-assisted interviews could assist clinicians by collecting a broad range of clinical information describing the problems of clinic-referred children. It is also suggested that considerably more research is needed into the possible benefits of computer technology in child and adolescent mental health services.  相似文献   
13.
A device called the Dex Frame has recently been marketed as an aid for children with specific learning difficulties. Using a test of reading speed and a test of reading accuracy we have attempted to evaluate the device. Two groups of children with learning difficulties were used, one having sole use of the device and being allowed to carry it with them and a second group who only used the device when attending for remedial tuition and assessment. The results show that no significant improvement occurred in reading performance of the groups with learning difficulties using the Dex Frame as compared with a control group. The teachers of the groups did, however, feel that on an individual basis some children (< 10%) expressed that they felt more comfortable using the device.  相似文献   
14.
This report describes the development of a series of highly potent quinoline-based leukotriene D4 (LTD4) receptor antagonists containing an N-benzyl-substituted phenyltetrazole moiety. They were designed to provide both the correct positioning of the acidic function and secondary lipophilic domain required for strong receptor binding. Members of this series possess high activity in blocking LTD4-induced contractions of isolated guinea pig ileum. Compound 32, LY287192 (2-[[5-[3-[2-(7-chloroquinolin-2- yl)ethenyl]phenyl]-2H-tetrazol-2-yl]methyl]-5-fluorobenzoic acid sodium salt), blocked contraction with a pKB value of 9.1 +/- 0.3. Qualitative structure-activity studies have demonstrated specific requirements for the best activity. In particular, ortho substitution of the benzyl group with an acidic function was crucial for maximum potency. In cases similar to 32, where the benzyl group possesses an ortho carboxylate, the N-2-substituted tetrazole isomer showed 100-fold greater activity relative to the corresponding N-1 isomer. This pattern was reversed when the acid was substituted at the para position. The quinoline unit may be replaced by other nitrogen-containing heterocycles.  相似文献   
15.
Plants traditionally employed for the treatment of malaria in certain areas of Brazil, where this disease is prevalent, were surveyed by interviewing natives and migrants in the Amazon Region. Forty-one plants used for malarial treatment and/or for the related symptoms (fever and liver disorders) were collected and identified. Given the potential of Brazil's forests and medicinal plants, research on traditional plant-based remedies in this country may lead to the development of new drugs.  相似文献   
16.
17.
18.
Safety of outpatient tonsillectomy and adenoidectomy   总被引:6,自引:0,他引:6  
Recent changes in reimbursement for tonsillectomy and adenoidectomy have resulted in a large number of these procedures being done on an outpatient basis. There is still considerable controversy, however, as to the safety of this concept. We reviewed the charts of 1000 consecutive patients who underwent these procedures. Three hundred ninety-six procedures were performed as inpatient surgery and 604 were performed as outpatient surgery. Patients were considered as candidates for outpatient surgery if they met specific criteria, such as good overall medical health, no central apnea, normal bleeding history and profile, and had adequate social considerations. The inpatient group included those patients who did not meet the criteria to be outpatients. We compared the complication rates of these two groups with regard to age, type of procedure performed (tonsillectomy, adenoidectomy, adenotonsillectomy), and indication for surgery in order to determine if there was any increased risk of outpatient surgery, despite strict selection criteria. The two groups were similar in their distribution with regards to age, sex, type of procedure, and indication for surgery. The overall complication rate for the entire group was 7.9%, with an 11.8% complication rate for inpatients and 4.1% complications for outpatients. The higher complication rate among the inpatient group is probably a direct result of the selection process because this group included the higher-risk patients. On the basis of these findings, we believe that surgery of the tonsils and adenoids can be performed safely as an outpatient procedure, regardless of age, indication, or procedure, if the candidates for ambulatory surgery are carefully selected by the surgeon.  相似文献   
19.
KA Forde 《Surgical endoscopy》1998,12(12):1375-1376
  相似文献   
20.
Forty-seven patients with frequently recurring genital herpes participated in one or more of five sequential trials of oral suppressive therapy with 200 mg of acyclovir three times daily from four to 12 months' duration. The prolonged use of acyclovir was extremely well tolerated, and treatment efficacy was sustained through successive studies. Recurrences in eight patients with repeated treatment "failures" were more effectively suppressed with higher doses of acyclovir. All patients experienced recurrent infections after the treatments were completed; however, the mean time to recurrence following each treatment period became progressively longer, and resumption of suppressive therapy was no longer warranted for ten patients. These data indicate the efficacy and safety of chronic suppressive therapy with acyclovir and the value of interrupting prolonged treatment to assess its further need.  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