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   181篇
  免费   15篇
妇产科学   13篇
基础医学   10篇
口腔科学   8篇
临床医学   25篇
内科学   39篇
皮肤病学   6篇
神经病学   3篇
外科学   47篇
综合类   6篇
一般理论   3篇
预防医学   16篇
药学   16篇
肿瘤学   4篇
  2016年   2篇
  2015年   2篇
  2014年   1篇
  2013年   4篇
  2012年   2篇
  2010年   4篇
  2009年   3篇
  2008年   1篇
  2005年   2篇
  2004年   1篇
  2002年   2篇
  2001年   3篇
  2000年   1篇
  1999年   7篇
  1998年   11篇
  1997年   7篇
  1996年   4篇
  1995年   3篇
  1994年   2篇
  1993年   4篇
  1992年   6篇
  1991年   10篇
  1990年   8篇
  1989年   5篇
  1988年   4篇
  1987年   3篇
  1986年   5篇
  1985年   2篇
  1984年   4篇
  1983年   8篇
  1982年   4篇
  1981年   4篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1977年   2篇
  1976年   2篇
  1975年   1篇
  1972年   1篇
  1970年   2篇
  1966年   1篇
  1959年   6篇
  1958年   15篇
  1957年   10篇
  1956年   5篇
  1955年   3篇
  1954年   8篇
  1949年   3篇
  1948年   3篇
  1947年   2篇
排序方式: 共有196条查询结果,搜索用时 3 毫秒
1.
We examine and refine the Fagerström Tolerance Questionnaire (FTQ; Fagerström, 1978). The relation between each FTQ item and biochemical measures of heaviness of smoking was examined in 254 smokers. We found that the nicotine rating item and the inhalation item were unrelated to any of our biochemical measures and these two items were primary contributors to psychometric deficiencies in the FTQ. We also found that a revised scoring of time to the first cigarette of the day (TTF) and number of cigarettes smoked per day (CPD) improved the scale. We present a revision of the FTQ: the Fagerström Test for Nicotine Dependence (FTND).  相似文献   
2.
The purposes of the present study were to compare the cardiovascular response patterns evoked by three versions of the cold pressor test (either forehead stimulation or hand or foot immersion) and to determine the reproducibility of the responses over a 2-week interval. Blood pressure, heart rate, stroke volume, cardiac output, total peripheral resistance, and systolic time intervals were obtained during rest and during the cold pressor test in 42 young men. Across conditions, the pressor response was supported by peripheral resistance increases with concomitant stroke volume decreases. Although the response panerns were generally similar across sites, exceptions were apparent for heart rate. Forehead stimulation was characterized by no significant change in heart rate, whereas limb (hand or foot) immersion was associated with significant heart rate acceleration. The responses elicited by the three cold pressor test conditions were reliable and showed little evidence of attenuation over the test-retest interval.  相似文献   
3.

A major focus of health system reform in Canada has been the regionalization of health services administration. With a goal of bringing decision-making closer to the community, there has been a commitment to public participation in planning by some health authorities. Women, however, often feel that their participation is minimal or their needs are not addressed. During regionalization of the Alberta health system, the Calgary Health Region (CHR) negotiated an agreement with the Salvation Army to provide women's health services through the Grace Women's Health Centre, a major part of the region's women's health program. We present a case study exploring the process and final agreement and the impact of this agreement on women's participation in health policy development. The historical context and the nature and impact of the agreement are described and several participation strategies that occurred within the partnership are discussed. The development of a formal partnership agreement, a governance model, was a success for public participation in this case; however, the greatest success for women was maintenance of a political space in which women's health as a priority could be discussed in a context where the forces against gender equity talk are strong.  相似文献   
4.
Fiane AE, Mollnes TE, Videm V, Hovig T, Høgåsen K, Mellbye OJ, Spruce L, Moore WT, Sahu A, Lambris JD. Compstatin, a peptide inhibitor of C3, prolongs survival of ex vivo perfused xenografts. Xenotransplantation 1999; 6: 000-000 ©Munksgaard, Copenhagen Compstatin, a newly described C3-binding peptide, inhibits complement activation by blocking C3 convertase-mediated cleavage of C3. As the complement activation is an essential part of the rejection reaction, we evaluated the ability of Compstatin to delay or prevent hyperacute rejection in an ex vivo xenograft model. Porcine kidneys were perfused with fresh human blood containing either Compstatin (n=6) or a control agent (n=6). Graft survival and activation of complement, leukocytes and platelets both in the fluid phase and in the tissue were examined. The survival of the Compstatin-perfused kidneys (median, 380 min) was significantly (P=0.0036) longer than that of the controls (median, 90 min). The classical complement pathway (C1rs-C1inhibitor and C4bc) was significantly and equally activated in both groups during the first 60 min. C3 activation products increased fivefold and terminal complement complex eightfold in the control group, but no increase occurred in the Compstatin group during this period. Immunohistochemistry showed less C3 and fibrin deposition and immuno-electron microscopy showed less terminal SC5b-9 complement complex deposition in the Compstatin group. A significant change in total white cells, neutrophils, myeloperoxidase, and expression of the surface activation markers CD11b (CR3) and CD35 (CR1) and CD62 L ( l -selectin) was observed in both groups. Leukocyte activation was lower in the Compstatin group but the difference was not statistically significant. There were no differences in platelet counts, thrombospondin, soluble P-selectin or β-thromboglobulin between the groups. We conclude that Compstatin prolongs graft survival and suggest that it may be a useful agent for attenuating hyperacute rejection by inhibiting C3 and thus terminal complement pathway activation.  相似文献   
5.
Aim: Polycystic kidney disease (PKD) in humans involves kidney cyst expansion beginning in utero. Recessive PKD can result in end‐stage renal disease (ESRD) within the first decade, whereas autosomal dominant PKD (ADPKD), caused by mutations in the PKD1 or PKD2 gene, typically leads to ESRD by the fifth decade of life. Inhibition of mTOR signalling was recently found to halt cyst formation in adult ADPKD mice. In contrast, no studies have investigated potential treatments to prevent cyst formation in utero in recessive PKD. Given that homozygous Pkd1 mutant mice exhibit cyst formation in utero, we decided to investigate whether mTOR inhibition in utero ameliorates kidney cyst formation in foetal Pkd1 homozygous mutant mice. Methods: Pregnant Pkd1+/? female mice (mated with Pkd1+/? male mice) were treated with rapamycin from E14.5 to E17.5. Foetal kidneys were dissected, genotyped and evaluated by cyst size as well as expression of the developmental marker, Pax2. Results: Numerous cysts were present in Pkd1?/? kidneys, which were twice the weight of wild‐type kidneys. Cyst size was reduced by a third in rapamycin‐treated Pkd1?/? kidney sections and kidney mass was reduced to near wild‐type levels. However, total cyst number was not reduced compared with control embryos. Pax2 expression and kidney development were unaltered in rapamycin‐treated mice but some lethality was observed in Pkd1?/? null embryos. Conclusion: Rapamycin treatment reduces cyst formation in Pkd1?/? mutant mice; therefore, the prevention of kidney cyst expansion in utero by mTOR inhibition is feasible. However, selective rapamycin‐associated lethality limits its usefulness as a treatment in utero.  相似文献   
6.
We studied the nutritional status of 32 patients (23 men), aged 50 (SD14) yr, on home hemodialysis (HHD) for one-138 months. No formal dietary restrictions were imposed. Anthropometric measurements were made using standard techniques, diet assessed by three-day dietetic diary and interview and plasma concentrations of nutrients were measured. Mean caloric intake was 29.4 (SD 10.7) kcal/kg; 24 (75%) patients had lower energy intakes than recommended for normals. Protein, vitamin C and folate intakes were above recommended minimum safe intakes. Intakes were less than recommended for calcium in four (13%) patients, iron in one (3%) and vitamin B12 in two (6%). One-third of both sexes had body mass indices (kg/m2) <25th percentile for normals, but none was <80% of ideal bodyweight. Arm muscle circumference was <10th percentile for normals in six men and three women. Triceps skin fold thickness was <10th percentile in four men (17%) and five women (55%). No anthropometric measurements were correlated with energy, protein or fat intake. Biochemical measurements were not useful in predicting protein intake. Neither nutritional intake nor anthropometric measurements were correlated with the duration of HHD. There was little evidence of malnutrition and wasting in this group of well rehabilitated HHD patients.  相似文献   
7.
The noise sampling period has been recognized as a cause of apparent sensing malfunction in demand pacemakers. Physiologic signals as well as external electromagnetic interference can cause certain demand pacemakers to remain refractory and escape asynchronously at a specified rate. In this case, noise mode reversion pacing at the programmed lower rate limit of a Cordis 415A DDD pacemaker was observed during exercise when P-waves fell within the noise sampling period.  相似文献   
8.
In order to define nyctohemeral plasma ACTH secretory patterns, frequency plasma ACTH samples were obtained in seven patients with untreated Cushing's disease (i.e. pituitary-dependent Cushing's syndrome), five Cushing's patients treated by bilateral adrenalectomy, four of whom had Nelson's syndrome, and one patient with 21-hydroxylase deficiency (congenital adrenal hyperplasia). A nyctohemeral rhythm of plasma ACTH concentration was apparent in the one patient with the adrenogenital syndrome but not in those with Nelson's syndrome or Cushing's disease. The effect of graded doses of dexamethasone, 2,8 or 32 mg per 24 h period, on plasma ACTH concentrations was studied in patients with untreated or treated Cushing's disease or Nelson's syndrome. In all of these hypercorticotrophic states, the mean plasma ACTH concentraton was not significantly affected by the smallest dose of dexamethasone, was partially suppressed by the intermediate dose, and further suppressed by the largest dose. In contrst, the patient with congenital adrenal hyperplasia and elevated plasma ACTH concentrations showed complete suppression of plasma ACTH levels following the smallest dose of dexamethasone. These findings indicate that there is resistance to ACTH suppression by dexamethasone in all stages of Cushing's disease and suggest that negative feedback of glucocorticoids may be involved in the pathogenesis of this disease.  相似文献   
9.
A bstract Autotransfusion of shed mediastinal blood following cardiac surgery is an important advance in this era of enhanced concern for transfusion transmitted diseases. The requirements necessary for the successful re-infusion of shed mediastinal blood are discussed and a system is described which is easy to use, simple in design and efficient in performance.  相似文献   
10.
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