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   534篇
  免费   26篇
耳鼻咽喉   7篇
儿科学   6篇
妇产科学   5篇
基础医学   36篇
口腔科学   3篇
临床医学   32篇
内科学   150篇
皮肤病学   1篇
神经病学   65篇
特种医学   35篇
外科学   35篇
综合类   14篇
一般理论   1篇
预防医学   39篇
眼科学   12篇
药学   22篇
肿瘤学   97篇
  2022年   5篇
  2021年   5篇
  2020年   3篇
  2019年   6篇
  2018年   6篇
  2017年   6篇
  2016年   8篇
  2014年   9篇
  2013年   17篇
  2012年   17篇
  2011年   15篇
  2010年   11篇
  2009年   8篇
  2008年   18篇
  2007年   22篇
  2006年   19篇
  2005年   23篇
  2004年   26篇
  2003年   30篇
  2002年   33篇
  2001年   15篇
  2000年   21篇
  1999年   22篇
  1998年   10篇
  1997年   4篇
  1996年   4篇
  1995年   6篇
  1994年   4篇
  1993年   9篇
  1992年   12篇
  1991年   9篇
  1990年   7篇
  1989年   5篇
  1988年   13篇
  1987年   16篇
  1986年   16篇
  1985年   8篇
  1984年   5篇
  1983年   7篇
  1982年   4篇
  1981年   5篇
  1980年   8篇
  1979年   14篇
  1978年   5篇
  1975年   2篇
  1974年   2篇
  1973年   11篇
  1972年   8篇
  1971年   4篇
  1968年   8篇
排序方式: 共有560条查询结果,搜索用时 15 毫秒
1.
BACKGROUND: Endothelin, a peptide with strong vasoconstrictive and mitogenic properties, has been found to increase after cardiac transplantation. We therefore assessed the association between its precursor peptide, big endothelin-1, and intimal hyperplasia and coronary flow reserve after heart transplantation. METHODS: Thirty-five patients without hemodynamically significant coronary artery disease after heart transplantation were investigated: Average peak flow velocity in the left anterior descending artery (LAD) was assessed by intracoronary Doppler at baseline as well as after injection of adenosine; coronary flow reserve was calculated as a ratio of both and was corrected for patient age and baseline average peak flow velocity. Lumen, intima + media and total vessel area were measured by intracoronary ultrasound. The plasma concentration of big endothelin-1 in venous blood was determined by radioimmunoassay. RESULTS: Patients with elevated big endothelin-1 levels (>2 fmol/ml) tended to have a decreased corrected coronary flow reserve (2.60 +/- 0.9 vs 3.21 +/- 1.0, p = 0.078). They also had a significantly larger intima + media area (5.82 +/- 2.9 vs 2.37 +/- 2.9 mm(2), p = 0.004) and total vessel area (18.36 +/- 5.8 vs 12.81 +/- 4.8 mm(2), p = 0.012) than those with normal plasma concentrations. CONCLUSIONS: Our study suggests an association between elevated big endothelin-1 plasma levels and the development of intimal hyperplasia and reduction of coronary flow reserve after cardiac transplantation.  相似文献   
2.
L Taksel  P Jolly  R Beran 《JAMA》1989,262(8):1020-1028
  相似文献   
3.
An open, multi-centre, general practice study was carried out in 1661 asthmatic patients to assess the efficacy, in terms of symptom relief and changes in lifestyle, of budesonide and to record objective lung function changes and any adverse events. After a 1-week run-in period on any pre-trial anti-asthma medication, patients received either 200 micrograms or 400 micrograms budesonide twice daily by metered dose inhaler for 4 weeks. Peak expiratory flow rate (PEFR) was measured by the doctor on entry, after the run-in, and at the end of the study and patients were asked to complete diary cards on a daily basis to record compliance, bronchodilator usage and the severity of cough, wheeze and sleep disturbance, and weekly to record 5 lifestyle assessments, e.g. physical activity. Analysis of data from the clinic visits and 1375 completed diary cards showed that PEFR increased significantly from 321 +/- 3 l/min at the end of the run-in to 368 +/- 3 l/min at the end of the trial; 77% of patients had an improved PEFR. Bronchodilator use decreased significantly from 4.2 +/- 0.1 times/day during the run-in period to 3.0 +/- 0.1 times/day at the end of the study; 65% of patients used less bronchodilator. Significant improvements were recorded in all the symptoms and lifestyle indices monitored; 76% of patients improved in at least 5 of the 11 assessments. Treatment-emergent adverse events occurred in 103 (6%) of patients: none was classified as serious or unexpected. No sub-group of patients was identified in which the results were at variance from the full sample. It is concluded that budesonide improves patients' lifestyle and ability to carry out normal activities, as well as improving PEFR and reducing bronchodilator use, in mild to moderately severe asthmatics treated in general practice.  相似文献   
4.
5.
6.
The intravenous (i.v.) injection of the human acute myelogenous leukemia cell line KBM-3 into severe combined immune deficient (SCID) mice results in disseminated multi-organ human disease involvement in these animals which leads to their death over a defined period of time. We utilized this model of human leukemia to investigate the in vivo therapeutic efficacy of the topoisomerase I inhibitor 9-aminocamptothecin (9-AC) given by two different routes. Mice injected with KBM-3 were divided into five groups. Group 1 received only diluent and served as control. The four remaining groups were treated with 9-AC four days a week for three consecutive weeks as follows: group 2 received 1.33 mg/kg/dose, i.v.; group 3, 1.33 mg/kg/dose, orally (p.o.); group 4, 2.0 mg/kg/dose i.v. and group 5, 2.0 mg/kg/dose p.o.. All animals in the control group died from disseminated human leukemia by day 64 from grafting, with a median survival of 59 days. Eleven out of 20 treated mice survived with no evidence of disease and were sacrificed at the termination of the experiment on day 128. PCR-assisted tissue analysis for the presence of human DNA showed no evidence of human leukemia. In conclusion, 9-AC is an active agent in SCID mice engrafted with human myelogenous leukemia and should be explored in phase I-II trials. Oral and intravenous routes are equally effective.  相似文献   
7.
Summary In a prospective study of 251 patients operated upon for lumbar disc herniation it has been investigated whether the preoperative and early postoperative values of Elastase--1 Proteinase Inhibitor (EPI) — an indicator of inflammatory processes — and C-reactive Protein (CRP) — a well known predictor of some postoperative complications — were correlated to the later development of discitis. Postoperatively discitis developed in 14 patients. A randomly choosen group of 15 complication-free patients out of the total of 251 cases was used as control group.Elevated EPI plasma values, especially in the pre-operative and first postoperative days, turned out to be significantly related to the likelyhood of later discitis development, but no such relation for the CRP plasma values could be established. Thus and early prediction of patients at risk for this complication seems to be possible by pre- and postoperative measurement of EPI. It could be justified —but its usefulness has yet to be proven — to give antibiotics prophylactically and other anti-inflammatory medication in patients with elevated pre- and postoperative EPI values.  相似文献   
8.
Two histological examinations are described. The first presents a full-thickness graft after extracorneal keratoplasty 2 years after transplantation. The graft is localized in the host tissue, externally lined by the thickened episclera and internally by the sclera. The reaction of the host tissue is slight and the graft is well preserved. In the second, a lamellar graft, rare capillaries grow 1 year after transplantation, the reaction of the host tissue is very mild, and the graft slowly changes into the original tissue of the host.  相似文献   
9.
Beran RG  Beran ME 《Epilepsia》2000,41(7):875-879
PURPOSE: Trials of antiepileptic medications are usually based in tertiary referral centers with teaching hospital resources. Epilepsy Research & Services (ERS) is part of a private outpatient neurological clinic that is involved in research as part of multicenter clinical trials, adhering to Good Clinical Research Practice. ERS is subject to external monitoring and auditing, but does so outside of the teaching hospital environment. METHODS: The clinic is operated by a neurologist supported by a research assistant, administrative and nursing staff and has no formal university attachment. Patients are recruited for trials from routine referrals for clinical care. The center has formal ties with the ethics committee of the local teaching hospital, but none of the team is formally attached to that hospital. RESULTS: The center conducted trials of zonisamide, oxcarbazepine, gabapentin, remacemide, tiagabine, vigabatrin, felbamate, and lamotrigine both as add-on trials in refractory seizure disorders and as monotherapy trials in de novo epilepsy. More than 200 patients have been recruited for trials at ERS (with some patients being involved in more than one trial). External review endorsed ERS as a superior environment for such research and as a model for other centers. CONCLUSIONS: Private practice is a viable alternative for the conduct of clincial trials and should be considered when establishing such protocols. Simplicity of administration and clinical practice, which more closely mirrors standard patient care, may enhance recruitment and management.  相似文献   
10.
Philadelphia chromosome-positive (Ph1) acute leukemia is a heterogeneous subset of acute leukemia with a poor prognosis. We studied five patients to determine the potential for phenotypic and molecular heterogeneity. Cellular characterization studies included light myeloperoxidase (L-MPO), terminal deoxynucleotidyl transferase (TdT), ultrastructural MPO (U-MPO), and immunophenotyping by flow cytometry using T11, T3, T4, T8, Leu 1, B1, Leu 12, HLA-DR (la), CALLA (J5), OKM1, My4, My7, My8, My9, and My10. DNA was analyzed for rearrangements of the breakpoint cluster region (bcr), immunoglobulin heavy chain, joining region (JH), immunoglobulin kappa light chain constant region (C kappa), and T cell receptor (TcR beta). RNA dot blots were hybridized by using molecular probes for MPO and TdT. We found that four of five cases were acute mixed-lineage leukemia (AMLL). One patient had acute unclassifiable leukemia. Of the four patients classified as having AMLL, three showed myeloid and lymphoid features, with one patient showing myeloid, T cell, and B cell features. The last case showed T cell and B cell features only. In one patient MPO/RNA was positive in spite of insufficient L-MPO or U-MPO to diagnose acute myelogenous leukemia (AML), thereby suggesting significant MPO gene expression before the production of sufficient MPO protein to meet the French-American-British criteria for AML. Three of the five patients showed rearrangement of bcr (cases 1, 2, and 5). Studies of these five patients support the concepts of molecular and phenotypic heterogeneity in Ph1 acute leukemia, demonstrate a high incidence of AMLL in this subset of acute leukemia, and support the use of lineage-associated molecular probes to define lineage at an earlier stage than previously possible.  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