全文获取类型
收费全文 | 2933篇 |
免费 | 241篇 |
国内免费 | 14篇 |
专业分类
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 |
出版年
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.
A controlled trial of scheduled replacement of central venous and pulmonary-artery catheters. 总被引:12,自引:0,他引:12
D K Cobb K P High R G Sawyer C A Sable R B Adams D A Lindley T L Pruett K J Schwenzer B M Farr 《The New England journal of medicine》1992,327(15):1062-1068
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.
M G Sawyer A Sarris P Baghurst 《The Australian and New Zealand journal of psychiatry》1992,26(2):223-231
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.
J S Sawyer R F Baldwin L E Rinkema C R Roman J H Fleisch 《Journal of medicinal chemistry》1992,35(7):1200-1209
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.
M G Brand?o T S Grandi E M Rocha D R Sawyer A U Krettli 《Journal of ethnopharmacology》1992,36(2):175-182
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.
20.
Acyclovir suppression of frequently recurring genital herpes. Efficacy and diminishing need during successive years of treatment 总被引:3,自引:0,他引:3
S E Straus K D Croen M H Sawyer A G Freifeld J M Felser J K Dale H A Smith C Hallahan S N Lehrman 《JAMA》1988,260(15):2227-2230
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