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   1984篇
  免费   223篇
  国内免费   20篇
耳鼻咽喉   3篇
儿科学   45篇
妇产科学   12篇
基础医学   304篇
口腔科学   74篇
临床医学   176篇
内科学   410篇
皮肤病学   46篇
神经病学   228篇
特种医学   180篇
外科学   229篇
综合类   43篇
预防医学   167篇
眼科学   11篇
药学   114篇
  2篇
中国医学   1篇
肿瘤学   182篇
  2021年   20篇
  2019年   16篇
  2018年   31篇
  2017年   37篇
  2016年   24篇
  2015年   32篇
  2014年   38篇
  2013年   56篇
  2012年   67篇
  2011年   82篇
  2010年   43篇
  2009年   59篇
  2008年   88篇
  2007年   85篇
  2006年   97篇
  2005年   82篇
  2004年   67篇
  2003年   56篇
  2002年   77篇
  2001年   43篇
  2000年   52篇
  1999年   75篇
  1998年   50篇
  1997年   53篇
  1996年   43篇
  1995年   37篇
  1994年   44篇
  1993年   36篇
  1992年   43篇
  1991年   28篇
  1990年   42篇
  1989年   65篇
  1988年   51篇
  1987年   60篇
  1986年   37篇
  1985年   61篇
  1984年   30篇
  1983年   27篇
  1982年   21篇
  1981年   13篇
  1980年   22篇
  1979年   16篇
  1978年   23篇
  1977年   18篇
  1976年   16篇
  1975年   17篇
  1974年   16篇
  1973年   15篇
  1972年   18篇
  1969年   13篇
排序方式: 共有2227条查询结果,搜索用时 15 毫秒
1.
Functional recovery, the goal of treatment, has long been overlooked in the assessment of effectiveness of pharmacological treatments. However, with the recent shift in paradigm, from syndromal–symptomatic recovery to functional recovery, there appears to be a new interest in the definition and evaluation of functional recovery. Since functional recovery lags symptomatic recovery, sometimes by months or years, the attainment of functional recovery will be determined by both efficacy and long-term compliance. Quetiapine, due to its efficacy in both mania and depression, and effect on cognition may lead to improved functioning in patients with bipolar disorder.  相似文献   
2.
Introduction: Suramin is a synthetic polysulfonated naphthylurea which has been used for the treatment of African trypanosomiasis and onchocerciasis, but since the mid-1980s has received attention as a possible antiretroviral and antineoplastic agent. Objective: This clinical trial of suramin was undertaken as a phase I/II study in patients with hormone-refractory prostate cancer, with the hypothesis that the intensity of therapy with suramin could be increased significantly if measures were undertaken to maintain the plasma concentrations of the drug under 300 μg/ml. Methods: We report the clinical results of this trial, wherein patients were treated at three different targeted plasma suramin concentrations (275, 215 and 175 μg/ml) for varying periods of time (2, 4 or 8 weeks), with delivery of the drug by continuous intravenous infusion. Results: The major toxicity observed in this trial was neurologic, consisting of a motor and sensory peripheral neuropathy that resulted in both paresis and paralysis of the limbs. Nearly all of this severe (CTEP grade III, IV) neurologic toxicity was observed in the patients treated at a plasma suramin concentration of 275 μg/ml for 4 or more weeks. A single patient treated at 215 μg/ml for 8 weeks developed moderate (CTEP grade III) proximal lower extremity weakness, and no patient treated at 175 μg/ml developed this toxicity. The second most common toxicity observed was infection of the central venous catheter. The overall response rate for all of the evaluable patients was 17% (13 of 75 patients). In addition, prostate-specific antigen (PSA)-defined responses were observed in six patients receiving therapy at 175 μg/ml, but these responses were confounded by cessation of therapy with flutamide during suramin treatment. Conclusions: In summary, although plasma suramin concentrations were maintained below 300 μg/ml, neurologic toxicity nonetheless occurred with high frequency in patients treated at 275 μg/ml for 4 or more weeks. Therapy at 215 and 175 μg/ml was in general well tolerated, but central venous catheter-related infection, as well as the inconvenience and expense of continuous infusional therapy, make this method of drug delivery impractical. Only moderate antitumor activity was observed during this trial, but it is possible that both continuation of flutamide and flutamide withdrawal during suramin therapy confounded the assessment of suramin’s activity in hormone-refractory prostate cancer. Received: 9 June 1995/Accepted: 18 March 1996  相似文献   
3.
Aims Cardiovascular disease (CVD) is a major complication of Type 2 diabetes mellitus. The renin‐angiotensin system (RAS) and nitric oxide production are both important regulators of vascular function and blood pressure. Genes encoding proteins involved in these pathways are candidates for a contribution to CVD in diabetic patients. We have investigated variants of the angiotensinogen (AGT), angiotensin converting enzyme (ACE), angiotensin type 1 receptor (AT1R) and endothelial nitric oxide synthase (NOS3) genes for association with subclinical measures of CVD in families with Type 2 diabetes mellitus (T2DM). Methods Atherosclerosis was measured by carotid intima‐media thickness and calcification of the carotid and coronary arteries in 620 European Americans and 117 African Americans in the Diabetes Heart Study. Because of the role of these systems in blood pressure regulation, blood pressure was also investigated. Results Compelling evidence of association was not detected with any of the SNPs with any outcome measures after adjustments for covariates despite sufficient power to detect relatively small differences in traits for specific genotype combinations. Conclusions Genetic variation of the RAS and NOS3 genes do not appear to strongly influence subclinical cardiovascular disease or blood pressure in this diabetic population.  相似文献   
4.
Numerous investigators have reported the safety, cost effectiveness, and low morbidity and mortality of percutaneous endoscopic gastrostomy (PEG) but not studies compare the results of gastroenterologists and surgeons performing PEG. In a retrospective review of PEG performed at our institution, morbidity and mortality were compared between these two groups. The procedure was performed by either the surgical service (n = 49) or gastroenterology service (n = 51). One hundred PEGs were successfully placed in 92 patients. Three placement failures occurred in the gastroenterology group. Major complications were defined as conditions requiring operative intervention or resulting in death. Minor complications, using a defined list (13 different complications), were those not serious or life-threatening, which were managed medically or resolved without treatment. Twenty-nine minor (17 patients) complications and 3 major (3 patients) complications occurred in the gastroenterology group. Thirteen minor (11 patients) complications and 4 major (4 patients) complications occurred in the surgery group. Overall 30-day mortality was 14 per cent (13 patients), two of which were probably procedure-related in the gastroenterology group. In both groups, there was no difference in the numbers of patients who had complications (P greater than 0.05). The complication rate (numbers of complications/number of patients) doubled in the gastroenterology group compared with the surgery group for minor (P less than 0.04) and total complications (minor and major--P less than 0.06). Since PEG is a procedure frequently performed by gastroenterologists, it is imperative that surgeons, particularly those not performing endoscopy, be aware of the potential morbidity associated with PEG.  相似文献   
5.
SUMMARY Four specialised air mattresses had interface pressure measured under six body sites prone to pressure sores in 10 subjects, supine and sitting. The mattresses were the Clinirest (SSI) and FirstStep (KCI) continuous airflow mattress overlays, and Airwave (Pegasus) and Nimbus (Huntleigh) alternating pressure air mattresses. On the mattress overlays, average supine interface pressures were 2.33 kPa (scapula), 4.15 kPa (elbow), 1.94 kPa (sacrum) and 2.79 kPa (buttock), although they were higher at the occiput (7.97 kPa) and heel (11.7 kPa). The alternating pressure air mattresses had an average minimum interface pressure close to zero for three sites, rising to 4.28 kPa under the heel. Average maximum interface pressures were 8.61 kPa (occiput), 5.21 kPa (scapula), 4.90 (elbow), 4.85 kPa (sacrum), 4.61 kPa (buttock) and 13.2 kPa (heel). No accepted scientific method exists for comparing the two types of mattress. Our data suggest a clinical benefit at the occiput and heel (supine) in using an alternating pressure air mattress and a benefit in using a continuous airflow mattress overlay at other sites.  相似文献   
6.
7.
Vasoactive intestinal peptide (VIP) has been suggested to be a mediator of vagal inhibition of airway tone and it has been assumed that VIP-containing nerve fibres in the airway arise from intrinsic ganglia. We have used a combination of double- and triple-labelling immunohistochemistry, retrograde axonal tracing, organotypic culture and nerve lesion studies, to identify the origin and distribution of neurons containing immunoreactivity (IR) to VIP in guinea pig airway smooth muscle. We also investigated whether immunoreactivity to other neuropeptides coexisted with VIP-IR within these neurons. We found that all VIP-IR nerve fibres in guinea pig tracheal smooth muscle also contained IR to neuropeptide Y (NPY) but not to tyrosine hydroxylase (TH), a marker for noradrenergic neurons. Both VIP-IR and NPY-IR were absent from nerve cell bodies in the tracheal plexus. After maintenance of isolated trachea in organotypic culture for 4 days, to allow degeneration of extrinsic nerve fibres, nerve fibres containing VIP-IR or NPY-IR were almost completely absent from tracheal smooth muscle. Of ganglia known to supply the trachea, coexistence of VIP-IR and NPY-IR was found only in cell bodies of the stellate ganglion. Retrograde tracing studies using the fluorescent tracer, DiI, confirmed that the stellate ganglion was the site of origin of neurons containing VIP-IR and NPY-IR supplying the airways. These neurons projected to the airways from the stellate ganglion both directly through the mediastinum, and via the cervical sympathetic trunk and vagus nerves. These results suggest that nerve fibres containing both VIP-IR and NPY-IR in the tracheal smooth muscle of the guinea pig are derived from non-noradrenergic cell bodies in the stellate ganglion. The absence of VIP-IR from vagal post-ganglionic neurons suggests that VIP cannot be a mediator of vagal inhibitory transmission in tracheal smooth muscle of this species.  相似文献   
8.
AIMS: Increased levels of inflammatory biomarkers, especially C-reactive protein (CRP), are associated with increased risk for cardiovascular disease (CVD) events, such as myocardial infarction, stroke, peripheral vascular disease, and sudden cardiac death. Medical interventions that increase CRP levels, such as hormone replacement therapy (HRT) in post-menopausal women, are under increasing scrutiny. The effect of HRT on CRP levels in women with Type 2 diabetes (T2DM) is not well documented, and conflicting conclusions have been reported. The aim of this study was to determine the influence of HRT on women with diabetes in a large cross-sectional study. METHODS: Three hundred and twenty-seven post-menopausal women with T2DM from the Diabetes Heart Study participated. Current use of HRT was determined and serum CRP levels were measured using a high-sensitivity ELISA kit. Generalized estimating equation methods were used to assess the relationship of multiple clinical and lifestyle (e.g. smoking) measures on CRP levels including differences between women taking HRT (HRT+) and not taking HRT (HRT-). RESULTS: Overall serum CRP levels were strongly associated with body mass index (P < 0.0001) and age (P < 0.0001). Of the women, 243 were not using HRT and 84 were using HRT. HRT+ and HRT- women did not differ significantly in measures of clinical traits, with the exception of higher mean low-density lipoprotein cholesterol in HRT- women (P = 0.004). In all models tested, HRT+ women had significantly higher circulating CRP levels, with P-values ranging from 0.0045 to 0.010. CONCLUSIONS: In this study of serum CRP concentration as a function of HRT in women with Type 2 diabetes, there was consistent evidence for increased circulating CRP levels in women receiving oestrogen-containing HRT. Whether HRT-induced increases in CRP can account for the adverse cardiovascular effects of HRT remains to be established; however, based on these data, there is little reason to believe that diabetic women would be spared from such an effect.  相似文献   
9.
Effect upon the EEG of acute injury to the brain stem activating system   总被引:8,自引:0,他引:8  
The effect upon the EEG in the unanesthetized "ecéphale isolé" of acute brain stem lesions in a position to involve the ascending reticular activating system has been studied. Elimination of the bulbar segment was without marked effect. Some synchronization followed elimination of the pons, but the most pronounced and prolonged changes occurred as a result of mesencephalic transection, or of discrete injury to the midbrain tegmentum or basal diencephalon, following which the EEG activation pattern of low voltage fast activity was reduced or abolished and the cortical record became dominated by recurring bursts or spindles of high voltage slow waves like those of normal sleep or barbiturate anesthesia. Bursts could be recorded from the intralaminar and other nuclei of the thalamus and these thalamic bursts were abolished by acute decortication. Conversely, cortical bursts were abolished by acute thalamic lesions. Possible interrelations of these regions in this activity is discussed. These results offer an explanation for the clinical observation of somnolence following basal injury to the brain, and suggest that a maintained influence of the ascending brain stem activating system underlies wakefulness, while absence of this influence precipitates sleep.  相似文献   
10.
MacEwan  DW 《Radiology》1987,163(2):559-563
Eleven radiologists appointed by the major radiological societies participated for the past 5 years in the development of the Health Policy Agenda for the American People. The Agenda is an action plan to address a wide variety of serious problems in medicine. The first phase involved establishment of 159 principles, broad value statements that were the foundation of the project. Phase 2 involved the development of policy proposals on 38 urgent issues for action in medical science; education; health resources; delivery mechanisms; evaluation, assessment, and control; and payment for services. These proposals are summarized in this report. The activities and recommendations of representatives for the field of radiology are described. The Agenda has been released, and an implementation phase has begun. It will likely be of great importance to the practice of radiology over the next decade. Important issues can be addressed by acting with the coalitions that are being formed from among the more than 150 participating organizations.  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