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   944篇
  免费   24篇
  国内免费   97篇
耳鼻咽喉   3篇
儿科学   38篇
妇产科学   1篇
基础医学   47篇
口腔科学   20篇
临床医学   129篇
内科学   210篇
皮肤病学   7篇
神经病学   123篇
特种医学   123篇
外科学   85篇
综合类   37篇
预防医学   25篇
眼科学   53篇
药学   86篇
肿瘤学   78篇
  2023年   4篇
  2022年   1篇
  2021年   11篇
  2020年   3篇
  2019年   10篇
  2018年   10篇
  2017年   8篇
  2016年   8篇
  2015年   4篇
  2014年   12篇
  2013年   29篇
  2012年   27篇
  2011年   26篇
  2010年   42篇
  2009年   34篇
  2008年   35篇
  2007年   89篇
  2006年   59篇
  2005年   42篇
  2004年   40篇
  2003年   29篇
  2002年   31篇
  2001年   31篇
  2000年   26篇
  1999年   33篇
  1998年   43篇
  1997年   42篇
  1996年   30篇
  1995年   34篇
  1994年   28篇
  1993年   42篇
  1992年   10篇
  1991年   14篇
  1990年   18篇
  1989年   31篇
  1988年   25篇
  1987年   16篇
  1986年   17篇
  1985年   14篇
  1984年   11篇
  1983年   4篇
  1982年   8篇
  1981年   4篇
  1980年   11篇
  1979年   2篇
  1978年   6篇
  1977年   8篇
  1976年   1篇
  1975年   2篇
排序方式: 共有1065条查询结果,搜索用时 15 毫秒
61.
Ultrasonic tissue characterization of the myocardium in anorexia nervosa   总被引:2,自引:0,他引:2  
AIM: To determine the systodiastolic variations in the integrated backscatter (IBS) signal of the myocardium in patients with anorexia nervosa. METHODS: 25 young women (aged 22.4 +/- 4.3 y) with overt anorexia nervosa, compared with 25 age-matched thin and 25 age-matched control women with body mass index >20 kg m(-2), underwent either conventional two-dimensional echocardiography or analysis of IBS cyclic variations. RESULTS: Compared with thin and control subjects, anorectic patients showed reduced left ventricular mass (LVM: 82.9 +/- 17.1 vs 119.9 +/- 13.8 and vs 126.12 +/- 16.4 g, p < 0.0001; LVM indexed 21.4 +/- 3.3 vs 29.4 +/- 2.5 and vs 31.2 +/- 3.1 g m(-2.7), p < 0.0001), and IBS cyclic variations (septum: -0.49 +/- 2.18 vs 6.86 +/- 1.3 and vs 6.61 +/- 1.74 dB p < 0.0001; posterior wall: 2.77 +/- 2.12 vs 7.15 +/- 2.12 and vs 7.48 +/- 2.23 dB, p < 0.01). CONCLUSION: Anorexia nervosa is associated with a significant reduction in the cyclic variation in IBS, which is also related to left ventricular hypotrophy. Ultrasonic tissue characterization could give an objective approach for the detection of myocardial structural properties and represent a preclinical index of myocardial dysfunction in anorexia nervosa.  相似文献   
62.
OBJECTIVES: To evaluate the degree of QT dispersion in a group of young women in the starvation phase of anorexia nervosa (AN) and its relation to left ventricular (LV) mass. STUDY DESIGN: Sixteen patients with self-induced starvation were matched with 16 women of normal weight and 16 constitutionally thin women (body mass index <20 kg/m2). Starving patients and control patients underwent an electrocardiogram and echocardiogram. QT intervals were measured from surface electrocardiograms and QT dispersion was defined as the difference between maximum QT and minimum QT occurring in any of the 12 leads. RESULTS: LV-chamber mass was significantly less in women with AN than in thin and normal-weight women. QT dispersion was significantly greater in AN than in the thin and control groups (QT dispersion: 50 +/- 14 vs 34 +/- 9 and 37 +/- 11 ms, P <.001; QT interval dispersion corrected for heart rate: 49+12 vs 34 +/- 9 and 36 +/- 7 ms, P <.01, respectively). A significant relation between QT dispersion and LV-mass index (r = -0.726, P <.01), and between QTc dispersion and LV mass index (r = -0.693, P < 0.01) were found only in the patients with AN. CONCLUSION: Starving patients show an increased QT dispersion related to reduced LV mass. This result could represent a useful indicator of arrhythmic risk and sudden death in AN.  相似文献   
63.
QT dispersion in elderly athletes with left ventricular hypertrophy   总被引:1,自引:0,他引:1  
The purpose of this study was to examine the QT dispersion in elderly endurance athletes with left ventricular (LV) hypertrophy. Sixteen athletes (males, mean age 67.6 +/- 4.5 years) with mild to moderate LV hypertrophy, were compared with 16 age-matched hypertensive patients with similar degree of LV hypertrophy and 16 age-matched healthy sedentary controls. All the participants underwent echocardiogram and 12-lead electrocardiogram. QT dispersion was defined as the difference between maximum and minimum QT intervals in the different leads. QT dispersion was corrected (QTc) for heart rate according to Bazett's formula. The results showed in athletes and hypertensive patients comparable LV mass (258.2 +/- 14.2 vs. 262.4 +/- 16.8 g, ns), which was significantly higher than that of controls (p < 0.001). Trained subjects had QT dispersion (38.6 +/- 10.2 ms) and QTc dispersion (39.4 +/- 11.3 ms) significantly lower than hypertensive patients (QT dispersion: 68.4 +/- 11.4 ms; QTc dispersion: 72.2 +/- 8.4, p < 0.001) and comparable with controls (QT dispersion: 44.3 +/- 8.4 ms; QTc dispersion: 46.2 +/- 6.2 ms, ns). In conclusion, in elderly athletes training-induced myocardial hypertrophy was characterized by a QT dispersion significantly lower than hypertensive myocardial hypertrophy. This could provide a simple and inexpensive screening method for differentiating physiologic from pathologic myocardial hypertrophy in elderly subjects.  相似文献   
64.
PURPOSE: we carried out a phase III randomized trial to compare vinorelbine-cisplatin regimen to gemcitabine-cisplatin regimen, and to a sequential administration of gemcitabine-ifosfamide followed by vinorelbine-cisplatin or the opposite sequence of vinorelbine-cisplatin followed by ifosfamide-gemcitabine according to the 'worst drug rule' hypothesis in patients with locally advanced unresectable stage IIIB or metastatic stage IV non-small cell lung cancer. The primary endpoint was survival parameters, while secondary endpoints included analysis of response rates and toxicity. PATIENTS AND METHODS: patients were randomized to receive: (a) gemcitabine 1000 mg/m(2) on days 1, 8 and 15 plus ifosfamide 1500 mg/m(2) on days 8-12 with mesna uroprotection (GI regimen) followed by vinorelbine 25 mg/m(2) on days 1 and 8 plus cisplatin 100 mg/m(2) on day 1 (GI --> VC regimen); (b) the opposite sequence (VC --> GI); (c) vinorelbine plus cisplatin as above described (VC regimen); or (d) gemcitabine 1400 mg/m(2) on days 1 and 8 plus cisplatin 100 mg/m(2) on day 8 (GC regimen). All regimens were given every 4 weeks. All patients were chemotherapy naive and had a ECOG PS 0-2. RESULTS: 400 patients were enrolled into the trial. Interim analysis after inclusion of 243 patients showed that ORR were 19% in the GI --> VC arm, 32% in the inverse sequence arm (CV --> GI), 42% in the VC arm, and 30% in the GC arm. The VC arm was statistically superior over the GI --> VC arm (p = 0.0074), but not over the other regimens. Median TTP was 3.1 months in the GI --> VC arm versus 5.0 months in the VC --> GI arm (p = 0.014). For these reasons the GI --> VC and VC --> GI arm were closed since the 'worst drug rule' hypothesis was rejected. Accrual in the VC and GC arms continued up to 140 and 138 patients respectively. Final ORR were 44% for the VC regimen (4 CR), and 34% for the GC regimen (1 CR). This difference was statistically significant (p = 0.032). OS was 9.0 and 8.2 months, respectively, with no statistically significant difference. The 1-year survival rate was 24 and 20%, respectively for VC and GC regimens. As expected the incidence of phlebitis was higher in the VC arm, while thrombocytopenia, flu-like syndrome and asthenia were more frequent in the GC arm. CONCLUSIONS: the results of this trial indicate that the combination of vinorelbine and cisplatin and that of gemcitabine and cisplatin are equivalent in terms of median TTP and OS, although the vinorelbine-cisplatin regimen is associated with a higher ORR. Both regimens may be considered as reference treatments for future studies. Moreover, our data reject the 'worst drug rule' hypothesis of sequential treatments in NSCCL at least with the combination used in this study.  相似文献   
65.
BACKGROUND: Because apomorphine is a dopamine agonist that acts on areas of the central nervous system believed to mediate penile erection, its use in erectile dysfunction (ED) has been investigated. However, it also produces nausea by dopamine-receptor stimulation of the chemotrigger zone in the brain. Therefore, a low plasma concentration, achieved rapidly, would be selective for the desired erectile response but would be below the dopamine threshold for nausea. OBJECTIVE: We evaluated the efficacy and tolerability of a dose-optimized regimen of a sublingual formulation of apomorphine (apomorphine SL) in the treatment of ED. METHODS: This was a multicenter, open-label, uncontrolled, Phase III dose-optimization study of apomorphine SL in heterosexual men with ED. The 2-week screening period, during which baseline severity of ED was determined using the International Index of Erectile Function, was followed by a 3-week dose-optimization period beginning at a dose of 2 mg. Patients were to make at least 2 attempts at intercourse per week throughout the study, placing 1 apomorphine tablet under the tongue beforehand. At the end of the first week, the dose could be increased to 3 mg at the discretion of the investigator; at the end of the second week, the dose could be increased to a maximum of 4 mg or decreased as needed. In the following 4-week treatment period, patients took their individual optimal doses. The primary efficacy variable was the percentage of attempts resulting in erections firm enough for intercourse, as assessed by investigators' review of data from patients' diaries. Secondary variables included the percentage of attempts resulting in successful intercourse, time to erection, and duration of erection. Information about adverse events, including their severity and relation to treatment, was determined on the basis of direct questioning, spontaneous reports, and review of patient diaries. RESULTS: The study enrolled 849 heterosexual men whose ages ranged from 31 to 78 years (mean, 58.1 years). They had a mean 5.7-year history of ED of varbus causes. ED was mild in 11.5% of the men, moderate in 23.8 c, and severe in 48.1%. When results of the last 8 attempts were pooled, representing the period during which patients were taking their optimal doses of apomorphine SL, the mean percentage of attempts resulting in erections firm enough for intercourse was 39.4%, compared with 13.1% at baseline; attempts resulting in intercourse increased from a mean of 12.7% at baseline to 38.3% with treatment. The average median time to erection was 23 minutes, and the average median duration of erection was 13 minutes. Nausea, the most common treatment-related adverse event (11.7%). was dose related and diminished with continued dosing. One patient had a single syncopal episode that was judged to be related to apomorphine SL. CONCLUSIONS: In the present study, a dose-optimization regimen of apomorphine SL-with dosing initiated at 2 mg and adjusted up to a maximum of 4 mg as needed-was effective and well tolerated in the treatment of ED, regardless of its cause or severity.  相似文献   
66.
We describe a 45-year-old man with biopsy proven cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). This patient demonstrated unique retinal findings, including arteriole narrowing and sheathing, irregular choroidal filling on fluorescein angiography, and patchy visual field loss. CADASIL is a hereditary, nonamyloid, nonathersclerotic microangiopathy. This disorder has been mapped to chromosome 19 with mutations in the Notch 3 gene. Deposits of granular osmiophilic material in the basal lamina of the smooth muscle cells of small vessels are considered pathognomonic for CADASIL and are typically seen only on electron microscopy. Although CADASIL is a systemic vascular disease affecting the entire arteriole tree, we are unaware of other reports describing the retinal findings observed in our patient.  相似文献   
67.
Opinion statement Treatment decisions for ocular myasthenia gravis (OMG) should be based on symptomatology. Local, nonpharmacologic treatment of ptosis or diplopia is successful in relatively few patients, and the majority of patients require drug therapy for satisfactory resolution of their symptoms. Response to anticholinesterase agents is variable, but should always be used as the first-line agent or adjunctive therapy in the treatment of OMG. It is unknown whether early treatment of OMG with corticosteroids or other immunosuppressive agents prevents or delays the development of generalized myasthenia, although some observations support this speculation. Corticosteroids are usually necessary for adequate improvement of ophthalmoplegia or ptosis. Surgical correction of ptosis or ocular motility deficits is not recommended for most patients with OMG, because of the fluctuating nature of the deficits and the high rate of recurrent deficits following surgery. All patients with OMG should be screened for the presence of thymus tumors, and thymectomy is recommended for all patients with a thymoma. Some patients with OMG who do not harbor a thymus tumor may also benefit from thymectomy.  相似文献   
68.
Background: An outbreak of food poisoning in a military establishment mess was investigated and remedial measures suggested.  相似文献   
69.
高效液相色谱法测定寒痹停片中士的宁含量   总被引:6,自引:0,他引:6  
目的:建立用HPLC测定寒痹停片中士的含量的方法。方法:氰基柱;流动相-甲醇-水-三乙胺-乙酸(9800:155:15:30);紫外检测波长254nm。结果:在4~20ug/ml范围内,标准曲线回归方程为:Y=-2803+8967x(r=0.9997),RSD=1.65%?加样回收率的平均值为99.82%。结论:实验表明,这是一个适用于生产控制和产品质量检验的简单、快速、准确的方法。  相似文献   
70.
Phaeochromocytomas are rare neuroendocrine tumours secreting high levels of catecholamines, able to exert serious metabolic and cardiovascular effects. The serious and potentially lethal cardiovascular complications of these tumours are due to the potent effects of secreted catecholamines, especially noradrenaline, the main transmitter released from sympathetic nerve terminals. Hypertension, tachycardia, pallor, headache and anxiety, usually dominate the clinical presentation. Occasionally, patients with predominantly epinephrine-secreting tumours present hypotension or even shock. Other cardiovascular complications of pheochromocytoma include ischaemic heart disease, acute myocardial infarction, cardiac arrhythmias, heart failure due to toxic cardiomyopathy, or pulmonary edema. Catecholamines have been shown to influence the extracellular matrix with collagen deposition and subsequent fibrosis in the arterial wall and in the myocardium. These morphofunctional changes of the myocardium and of arterial wall can be emphasized by ultrasound imaging. Indeed, ultrasound imaging of the myocardium and arterial wall not only identifies wall thickness but also contains information on texture that may be revealed by acoustic tissue characterization. The latter can be quantified through videodensitometric analysis of echographic images or through ultrasonic integrated backscatter signal analysis. This paper reviews cardiovascular complications in patients with pheochromocytoma and utility of the new ultrasound technique as backscatter signal. It is useful for evaluating preclinical pathological morphofunctional changes of the myocardium and arterial wall, characterized by increased collagen content in pheochromocytoma patients. The recognition of early catecholamine-induced alterations in patients with pheochromocytoma, is important to prevent at least morbidity and mortality, before surgical treatment.  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