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   2025篇
  免费   245篇
  国内免费   11篇
耳鼻咽喉   15篇
儿科学   85篇
妇产科学   47篇
基础医学   225篇
口腔科学   44篇
临床医学   194篇
内科学   336篇
皮肤病学   76篇
神经病学   141篇
特种医学   104篇
外科学   371篇
综合类   58篇
一般理论   5篇
预防医学   355篇
眼科学   9篇
药学   115篇
中国医学   1篇
肿瘤学   100篇
  2021年   23篇
  2020年   21篇
  2019年   30篇
  2018年   31篇
  2017年   38篇
  2016年   41篇
  2015年   43篇
  2014年   56篇
  2013年   95篇
  2012年   95篇
  2011年   84篇
  2010年   77篇
  2009年   81篇
  2008年   79篇
  2007年   83篇
  2006年   67篇
  2005年   68篇
  2004年   71篇
  2003年   67篇
  2002年   69篇
  2001年   58篇
  2000年   58篇
  1999年   42篇
  1998年   48篇
  1997年   45篇
  1996年   46篇
  1995年   35篇
  1994年   33篇
  1993年   28篇
  1992年   34篇
  1991年   34篇
  1990年   37篇
  1989年   42篇
  1988年   41篇
  1987年   41篇
  1986年   33篇
  1985年   30篇
  1984年   21篇
  1983年   22篇
  1981年   18篇
  1979年   16篇
  1978年   25篇
  1977年   17篇
  1976年   16篇
  1974年   28篇
  1972年   23篇
  1970年   17篇
  1969年   16篇
  1968年   15篇
  1966年   19篇
排序方式: 共有2281条查询结果,搜索用时 15 毫秒
991.
Fluorescent protease histochemical analysis of muscle biopsy specimens from two patients with nemaline myopathy revealed the apparent absence of one proteolytic enzyme, dipeptidyl peptidase. Although the function of peptidases in normal muscle is obscure, this abnormality suggests that proteases may participate in posttranslational modification of proteins that are to be assembled into Z lines or, alternatively, in the disassembly and degradation of Z-line material.  相似文献   
992.
We investigated 18 sets of blood donors from 12 to 50 months after they donated blood to recipients who subsequently developed the acquired immunodeficiency syndrome (AIDS). Within each donor set, only one donor was suspected of having transmitted the disease (ie, member of an AIDS risk group). The other donors (n = 189) were not risk group members and served as controls. A number of laboratory tests distinguished suspected from nonsuspected donors, including determination of T helper/T suppressor cell ratio, antibody to hepatitis B core antigen, and immune complexes, but none of these was as sensitive and specific as tests for antibody to the human retrovirus, HTLV-III/LAV.  相似文献   
993.
994.
The authors used the 2-[14C]deoxyglucose method to study local spinal and cerebral glucose utilization simultaneously during 1.2 per cent halothane anaesthesia in adult Sprague-Dawley rats. In conscious animals (n = 5) the rate of glucose utilization in lumbar spinal gray matter was about 50 per cent lower than that of cerebral cortex. Halothane anaesthesia (n = 6) reduced spinal cord and cerebral metabolic rate. Spinal glucose utilization was reduced 12-35 per cent, but this was less than the 45-70 per cent decrease halothane produced in 8 of 16 cerebral structures examined and was independent of the hypotension produced. These results indicate that halothane is a spinal metabolic depressant but that its effects on this tissue are substantially less than those it has on many cerebral structures.  相似文献   
995.
Obstetric epidural anaesthesia in patients with Harrington instrumentation   总被引:1,自引:0,他引:1  
This five-year retrospective study reviews our experience with epidural obstetric analgesia in patients with previous Harrington rod instrumentation (HRI) for correction of idiopathic scoliosis. Patients were identified by the presence of an antepartum anaesthetic consultation for HRI. The anaesthetic record was examined to determine the frequency of epidural catheter insertion and any problems related to this procedure. Nine epidural insertions were attempted in the 16 patients identified. Five were uncomplicated but four were complicated by one or more of: failure to identify the epidural space, blood vessel trauma, dural puncture, failure to obtain analgesia or the need for multiple attempts before successful insertion. There were no sequelae related to epidural insertion. There were no sequelae related to epidural insertion. We conclude that patients with HRI may be offered epidural anaesthesia for labour and delivery provided that they are informed of the increased risk of complications.  相似文献   
996.
We present a case of del(14)(q21) as a sole abnormality in a 4-year-old boy diagnosed with precursor B-cell acute lymphoblastic leukemia (pre-B ALL). To our knowledge, this is the first case of isolated del(14)(q21) in pre-B ALL. Two pretreatment bone marrow samples obtained 5 days apart were analyzed by cytogenetics. The G-banded karyotypes of the two samples were similar, differing only in the ratio of normal/abnormal metaphases detected. Both samples showed a del(14)(q21) as the only abnormality. Fluorescence in situ hybridization performed using the probes TEL/AML1 and immunoglobulin heavy chain (IGH) showed no fusion involving the TEL and AML1 genes and only a single IGH signal in 20% of the interphase cells analyzed.  相似文献   
997.
This study's purpose was to examine the extent to which participants (N = 143) receiving cognitive-behavioral therapy for bulimia nervosa (BN) reported implementing therapeutic strategies to abstain from BN behaviors, and to assess whether use of specific strategies predicts outcome at treatment end and 1- and 6-month follow-up. Frequency of outcome expectancies (OE), stimulus-response prevention (SRP), and social support-seeking (SSS) strategies significantly increased by end of treatment. By 1-month follow-up, use of SSS, not OE or SRP, declined significantly relative to treatment end. Although frequency of coping strategy use at treatment end did not predict 1-month BN symptom remission, SSS use at 1-month follow-up predicted 6-month remission. Findings highlight the importance of social support to maintain treatment gains.  相似文献   
998.

Background  

The increased survival of preterm and very low birth weight infants in recent years has been well documented but continued surveillance is required in order to monitor the effects of new therapeutic interventions. Gestation and birth weight specific survival rates most accurately reflect the outcome of perinatal care. Our aims were to determine survival to discharge for a large Canadian cohort of preterm infants admitted to the neonatal intensive care unit (NICU), and to examine the effect of gender on survival and the effect of increasing postnatal age on predicted survival.  相似文献   
999.
BACKGROUND: Reperfusion injury continues to significantly affect patients undergoing lung transplantation. Isolated lung models have demonstrated that adenosine A 2A receptor activation preserves function while decreasing inflammation. We hypothesized that adenosine A 2A receptor activation by ATL-146e during the initial reperfusion period preserves pulmonary function and attenuates inflammation in a porcine model of lung transplantation. METHODS: Mature pig lungs preserved with Viaspan (Barr Laboratories, Pomona, NY) underwent 6 hours of cold ischemia before transplantation and 4 hours of reperfusion. Animals were treated with (ATL group, n = 7) and without (IR group, n = 7) ATL-146e (0.05 microg kg -1 . min -1 ATL-146e administered intravenously for 3 hours). With occlusion of the opposite pulmonary artery, the animal was maintained for the final 30 minutes on the allograft alone. Recipient lung physiology was monitored before tissue evaluation of pulmonary edema (wet-to-dry weight ratio), myeloperoxidase assay, and tissue tumor necrosis factor alpha by means of enzyme-linked immunosorbent assay. RESULTS: When the ATL group was compared with the IR group, the ATL group had better partial pressure of carbon dioxide (43.8 +/- 4.1 vs 68.9 +/- 6.3 mm Hg, P < .01) and partial pressure of oxygen (272.3 +/- 132.7 vs 100.1 +/- 21.4 mm Hg, P < .01). ATL-146e-treated animals exhibited lower pulmonary artery pressures (33.6 +/- 2.1 vs 47.9 +/- 3.5 mm Hg, P < .01) and mean airway pressures (16.25 +/- 0.08 vs 16.64 +/- 0.15 mm Hg, P = .04). ATL-146e-treated lungs had lower wet-to-dry ratios (5.9 +/- 0.39 vs 7.3 +/- 0.38, P < .02), lower myeloperoxidase levels (2.9 x 10 -5 +/- 1.2 x 10 -5 vs 1.3 x 10 -4 +/- 4.0 x 10 -5 DeltaOD mg -1 . min -1 , P = .03), and a trend toward decreased lung tumor necrosis factor alpha levels (57 +/- 12 vs 96 +/- 15 pg/mL, P = .06). The ATL group demonstrated significantly less inflammation on histology. CONCLUSION: Adenosine A 2A activation during early reperfusion attenuated lung inflammation and preserved pulmonary function in this model of lung transplantation. ATL-146e and similar compounds could play a significant role in improving outcomes of pulmonary transplantation.  相似文献   
1000.
CONTEXT: Public opinion is important in determining condom and condom education policies in public high schools.
METHODS: A random telephone survey of 517 Indiana residents was conducted from July through October 2003 to assess public opinion about education on correct condom use for HIV and STD prevention; condom availability in Indiana public high schools; and issues related to condom use, effectiveness and promotion. Data were analyzed using bivariate and linear regression techniques.
RESULTS: A majority of respondents strongly or somewhat agreed that instruction on correct condom use for HIV and STD prevention should be provided in public high schools (77%), classroom instruction should include condoms (71%), only medically accurate information about condoms should being given (94%) and the federal government should promote condoms (70%). Fewer than half (48%) strongly or somewhat agreed that condoms should be made available to teenagers in public high schools without parental permission. Nearly all (92%) considered condoms at least somewhat effective in preventing HIV and other STDs. Non-Republican party affiliation, younger age and condom use within the previous five years were each significantly associated with having positive opinions on many of the condom-related statements.
CONCLUSIONS: Public opinion appears to support the provision of correct condom use information in Indiana public schools. Schools should consider providing only medically accurate information about condoms and including condoms in instruction so students can see and touch them.  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