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   753篇
  免费   22篇
  国内免费   2篇
儿科学   9篇
妇产科学   8篇
基础医学   132篇
口腔科学   26篇
临床医学   36篇
内科学   188篇
皮肤病学   16篇
神经病学   86篇
特种医学   14篇
外科学   115篇
预防医学   18篇
眼科学   21篇
药学   25篇
肿瘤学   83篇
  2024年   2篇
  2023年   8篇
  2022年   9篇
  2021年   9篇
  2020年   9篇
  2019年   6篇
  2018年   9篇
  2017年   7篇
  2016年   7篇
  2015年   14篇
  2014年   16篇
  2013年   24篇
  2012年   52篇
  2011年   56篇
  2010年   16篇
  2009年   27篇
  2008年   38篇
  2007年   40篇
  2006年   29篇
  2005年   32篇
  2004年   30篇
  2003年   35篇
  2002年   31篇
  2001年   21篇
  2000年   26篇
  1999年   28篇
  1998年   11篇
  1997年   11篇
  1996年   13篇
  1995年   6篇
  1994年   13篇
  1993年   10篇
  1992年   33篇
  1991年   17篇
  1990年   17篇
  1989年   11篇
  1988年   12篇
  1987年   9篇
  1986年   9篇
  1985年   5篇
  1984年   4篇
  1983年   1篇
  1976年   1篇
  1973年   2篇
  1972年   3篇
  1971年   3篇
  1970年   3篇
  1969年   1篇
  1968年   1篇
排序方式: 共有777条查询结果,搜索用时 15 毫秒
11.
We synthesized poly (DL-lactic acid)-fentanyl composites and compared the duration of analgesia after the administration of a single intrathecal dose of these agents in rats. The drug was injected with an intrathecal catheter into the intrathecal space. Fentanyl composites or plain fentanyl in doses of 2.5 or 25 micrograms were administered, respectively. Animals were then tested for analgesia using the tail-flick test. The release rate of fentanyl from fentanyl composites in vitro was also evaluated. The antinociceptive effect of fentanyl composites (25 micrograms) was significantly longer than that of plain fentanyl. Administration of poly (DL-lactic acid) alone did not induce the antinociceptive effect. Four of 7 animals given plain fentanyl (25 micrograms) exhibited temporary respiratory depression, but none of the animals given fentanyl composites showed this response. In vitro experiments demonstrated a slow release of fentanyl from the fentanyl composites. We conclude that the antinociceptive effect of fentanyl can be prolonged when administered as a poly (DL-lactic acid)-fentanyl composite in the intrathecal space with decreased systemic side effects compared with the plain formulation.  相似文献   
12.
We analyzed the pre-C and core region of hepatitis B virus (HBV) DNA by a polymerase chain reaction in 22 chronic carriers. In 9 hepatitis B e antigen-positive asymptomatic carriers, a single DNA band was detected at the expected size, whereas additional shorter DNA bands were observed in 7 out of 11 patients with chronic hepatitis. The smaller-sized DNAs from one chronic hepatitis patient had various lengths of deletions spanning from 105 to 183 bp in the middle of the core gene, and all deletions included common nucleotide sequences. All of the smaller-sized DNAs from the other patients proved to be variant core genes. They were deleted in similar regions by Southern analysis using oligonucleotide probes. A follow-up study revealed that four out of seven chronic hepatitis patients with a short core gene seroconverted to antibody to hepatitis B e antigen, but those with only a "wild type" did not. In another set of sequence studies, clones isolated from two chronic carriers displayed heterogeneity of the pre-C and core gene which was more often present in sera with normal alanine aminotransferase levels than with abnormal levels. These results suggest that mutant HBV alters the host immune response, and may modulate the clinical course of HBV infection. An alternative possibility is that chronic hepatitis selects for mutant forms.  相似文献   
13.
The present study was conducted to compare the pharmacokinetics (PK) of low-dose versus high-dose medroxyprogesterone (MPA) as a once-daily oral administration. Of 32 patients, all women, enrolled in this PK study, 18 received 600 mg MPA daily and 14 received 1200 mg daily. Detailed PK data were obtained on day 1 and after more than 4 weeks of MPA treatment. In addition, multiple data for the minimum steady-state concentration (Css min) were analyzed. The MPA serum concentrations were measured by high-performance liquid chromatography. Wide interpatient variability was found in the PK parameters obtained both on day 1 and after more than 4 weeks. There were no clear relationships between the oral dose and the MPA peak concentration (Cmax), area under the time versus concentration curve (AUC), or mean Css min. Weight gains of 10% or more were demonstrated more frequently in the high-dose group (P<0.01). Liver dysfunction (n=5) did not influence the PK of MPA. Five patients demonstrated extremely low AUC and Cmax (<10 ng/ml) values on day 1. Phenobarbital, dexamethasone and betamethasone were being taken concomitantly with the MPA each by one patient. The serum MPA concentrations were markedly increased after the discontinuation of phenobarbital in that patient, suggesting a drug interaction. At present we cannot recommend the high dose of MPA, except in clinical studies, from a PK or a pharmacodynamic points of view. Received: 2 May 1997 / Accepted: 13 October 1997  相似文献   
14.
15.
Microscopic polyangiitis associated with diffuse panbronchiolitis   总被引:1,自引:0,他引:1  
There are several case reports of systemic vasculitis associated with chronic suppurative lung diseases. We describe a 46-year-old female, previously diagnosed as having diffuse panbronchiolitis (DPB), presenting with hemosputum and dyspnea. Her serum titer of MPO-ANCA was positive together with a high titer of BPI-ANCA. Chest X-ray and chest CT scan showed pulmonary hemorrhage, and the renal biopsy specimen revealed necrotizing, crescentic glomerulonephritis. She was diagnosed as having ANCA-associated vasculitis, and more specifically, microscopic polyangiitis accompanied by DPB. She was treated with methylprednisolone pulse therapy, followed by intravenous cyclophosphamide. This case suggested a possible association with chronic bacterial infection, which may play a role in the pathogenesis of ANCA-associated vasculitis.  相似文献   
16.
The clinicopathological and biological significance of Hodgkin's disease and non-Hodgkin's lymphoma, which are infrequently encountered in women of childbearing age, remains to be clarified. We recently reviewed 4 cases of non-Hodgkin's lymphoma of the T/natural killer (T/NK)-cell phenotype, all of which were associated with pregnancy and characterized by the expression of the cytotoxic granule-associated proteins T-cell intracellular antigen-1 and/or granzyme B. The 4 cases selected had presented between November 1993 and May 1999. The criteria for selection were that the onset of clinical manifestations occurred during pregnancy or within 6 months after delivery. The patients comprised 1 patient with p80/anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALCL), 1 with p80/ALK-negative ALCL, and 2 with peripheral T/NK-cell lymphomas of unspecified type. The diseases followed aggressive clinical courses: 3 patients died within 6.5 months after diagnosis, and only 1 was still alive with the disease 17 months after diagnosis. The diseases appeared to progress rapidly after delivery. Maternal immunity and hormonal changes during pregnancy may be closely related to the biological behavior of these unusual tumors.This study is, to the best of our knowledge, the first to address pregnancy-associated cytotoxic lymphoma.  相似文献   
17.
This paper investigated the efficacy of passive protection provided by milk (immunized milk) against enterovirus infection in mice experimentally infected with enterovirus. Milk with a high antibody titer against six enterovirus serotypes was prepared from hyperimmunized goat. In vivo and in vitro experiments were performed and the results showed that immunized milk has an antiviral activity against enterovirus infection. Further observation was performed using Coxsackie B 3 virus (CVB 3). When immunized milk was orally applied to mice prior to oral inoculation with CVB 3, preventive effects against viral infection such as reduction of histopathological changes in the heart and reduced detection of the virus genome in the organs were seen. The antiviral effect was also indicated by the increase of CD4+T cells proportion in the i-IEL. The proportion of virus specific CD4+T cells was increased in mice treated with immunized milk, whereas no such increase was detected in control mice. These results suggest that oral application of immunized milk is not only capable of preventing viral infection but also induces specific immunological responses. These phenomena may play an important role in host defense mechanisms.  相似文献   
18.
Atrioventricular nodal reentrant tachycardia (AVNRT) is a relatively common paroxysmal supraventricular tachycardia. This study investigated whether adenosine-5'-triphosphate (ATP) injection during sinus rhythm might be useful in the noninvasive diagnosis of dual AV nodal pathways. The study group consisted of 9 patients with slow/fast AVNRT and 11 control patients without antegrade dual AV nodal physiology (DAVNP). ATP (2.5 to 30 mg, in 2.5-mg increments was injected during sinus rhythm until signs of DAVNP (> or = 50 msec increase or decrease in AH or PR interval in two consecutive beats) or > or = second-degree AV block was observed. DAVNP was diagnosed by ATP test in all 9 patients with slow/fast AVNRT. DAVNP was observed by ATP test in 3 of the 11 control patients. Thus, the test had a sensitivity of 100% and specificity of 73%. ATP test given during sinus rhythm is useful for identifying patients with dual AV nodal pathways who are prone to AVNRT.  相似文献   
19.
Because the current interferon (IFN)-based treatment for hepatitis C virus (HCV) infection has a therapeutic limitation and side effects, a more efficient therapeutic strategy is desired. Recent studies show that supplementation of vitamin D significantly improves sustained viral response via IFN-based therapy. However, mechanisms and an active molecular form of vitamin D for its anti-HCV effects have not been fully clarified. To address these questions, we infected HuH-7 cells with cell culture-generated HCV in the presence or absence of vitamin D(3) or its metabolites. To our surprise, 25-hydroxyvitamin D(3) [25(OH)D(3) ], but not vitamin D(3) or 1,25-dihydroxyvitamin D(3) , reduced the extra- and intracellular levels of HCV core antigen in a concentration-dependent manner. Single-cycle virus production assay with a CD81-negative cell line reveals that the inhibitory effect of 25(OH)D(3) is at the level of infectious virus assembly but not entry or replication. Long-term 25(OH)D(3) treatment generates a HCV mutant with acquired resistance to 25(OH)D(3) , and this mutation resulting in a N1279Y substitution in the nonstructural region 3 helicase domain is responsible for the resistance. Conclusion: 25(OH)D(3) is a novel anti-HCV agent that targets an infectious viral particle assembly step. This finding provides insight into the improved efficacy of anti-HCV treatment via the combination of vitamin D(3) and IFN. Our results also suggest that 25(OH)D(3) , not vitamin D(3) , is a better therapeutic option in patients with hepatic dysfunction and reduced enzymatic activity for generation of 25(OH)D(3) . (HEPATOLOGY 2012).  相似文献   
20.

Purpose

Diabetes mellitus (DM) is known as an important risk factor for surgical site infection (SSI) in spine surgery. It is still unclear however which DM-related parameters have stronger influence on SSI. The purpose of this study is to determine predisposing factors for SSI following spinal instrumentation surgery for patients with DM.

Methods

110 DM patients (66 males and 44 females) who underwent spinal instrumentation surgery in one institute were enrolled in this study. For each patient, various preoperative or intraoperative parameters were reviewed from medical records. Patients were divided into two groups (SSI or non-SSI) based on the postoperative course. Each parameter between these two groups was compared. Univariate and multivariate analyses were performed to determine predisposing factor for SSI.

Results

The SSI group consisted of 11 patients (10 %), and the non-SSI group of 99 patients (90 %). Univariate analysis revealed that preoperative proteinuria (p = 0.01), operation time (p = 0.04) and estimated blood loss (p = 0.02) were significantly higher in the SSI group compared to the non-SSI group. Multivariate logistic regression identified preoperative proteinuria as a statistically significant predictor of SSI (OR 6.28, 95 % CI 1.58–25.0, p = 0.009).

Conclusions

Proteinuria is a significant predisposing factor for SSI in spinal instrumentation surgery for DM patients. DM patients with proteinuria who are likely to suffer latent nephropathy have a potential risk for SSI. For them less invasive surgery is recommended for spinal instrumentation. In this retrospective study, there was no significant difference of preoperative condition in glycemic control between the two groups.  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