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   820篇
  免费   102篇
  国内免费   10篇
耳鼻咽喉   5篇
儿科学   19篇
妇产科学   27篇
基础医学   97篇
口腔科学   20篇
临床医学   208篇
内科学   129篇
皮肤病学   2篇
神经病学   88篇
特种医学   100篇
外科学   78篇
综合类   17篇
预防医学   57篇
眼科学   9篇
药学   34篇
中国医学   1篇
肿瘤学   41篇
  2023年   7篇
  2021年   8篇
  2019年   9篇
  2018年   13篇
  2017年   13篇
  2016年   13篇
  2015年   24篇
  2014年   28篇
  2013年   28篇
  2012年   28篇
  2011年   25篇
  2010年   23篇
  2009年   27篇
  2008年   35篇
  2007年   37篇
  2006年   26篇
  2005年   26篇
  2004年   26篇
  2003年   14篇
  2002年   27篇
  2001年   25篇
  2000年   19篇
  1999年   24篇
  1998年   28篇
  1997年   28篇
  1996年   29篇
  1995年   14篇
  1994年   17篇
  1993年   18篇
  1992年   16篇
  1991年   16篇
  1990年   11篇
  1989年   18篇
  1988年   18篇
  1987年   24篇
  1986年   17篇
  1985年   18篇
  1984年   12篇
  1983年   11篇
  1982年   10篇
  1981年   6篇
  1980年   6篇
  1979年   10篇
  1978年   10篇
  1976年   8篇
  1975年   5篇
  1974年   14篇
  1972年   7篇
  1971年   7篇
  1969年   5篇
排序方式: 共有932条查询结果,搜索用时 203 毫秒
31.
32.
The aim of this study was to determine the effectiveness of uterine artery embolization (UAE) as a primary treatment method in treatment of symptomatic fibroids, whether there are any preembolization MRI characteristics of fibroid predictive of reduction in volume and assess reduction in uterine and dominant fibroid volumes using ultrasound (US) and MRI. Study was carried out in total of 32 patients aged 25–49 years (mean 40.9 years). Uterine and dominant fibroid volume were determined using US and MRI before UAE, MRI and US at 3 months and US alone at 6 and 12 months post‐UAE, supplemented by clinical evaluation at interval of 3, 6 and 12 months. Procedure was carried out through unilateral femoral puncture using poly vinyl alcohol (PVA) particles 355–500 μm in size. All 32 patients had successful procedures. Overall, 25 patients responded, giving a clinical success rate of 78.12%. Mean reduction in volume of uterus and fibroid was 33 and 59.7% and 48.9 and 75.5% on US at 3 and 12 months respectively, and 33.3 and 58.6% on MRI at 3 months. Volume reduction on US and MRI at 3 months was highly correlative. There was no statistical difference in size reduction in volume of fibroids, which were hypointense or hyperintense on T2‐weighted image (T2WI) on pre‐UAE MRI. Uterine artery embolization leads to good technical success and fibroid volume reduction. Ultrasound alone may be used for follow up of patients post‐UAE. Preprocedure signal characteristics on T2WI are not predictors of volume reduction after UAE.  相似文献   
33.
The relative contribution of the lymph and blood in the absorption of darbepoetin alfa (DA) from different s.c. injection sites was determined using a central lymph-cannulated sheep model. DA was administered to parallel groups either as a bolus i.v. injection (0.5 mug/kg) into the jugular vein or as a bolus s.c. injection (2 mug/kg) into the interdigital space, the abdomen, or the shoulder. In the lymph-cannulated groups, the thoracic lymph duct was cannulated for continuous collection of central lymph, and blood samples were periodically collected via the jugular vein in all the groups. The concentration of DA in serum and lymph was determined by enzyme-linked immunosorbent assay. The total fraction of the dose reaching the systemic circulation and the fractions absorbed via the lymph and the blood were determined. A pharmacokinetic model was constructed to simultaneously fit the data from all the treatment groups. Absorption was essentially complete for all three injection sites in non-lymph-cannulated s.c. groups, but the rates of absorption differed significantly. Based on the modeling results for the lymph-cannulated groups, the lymphatics represented the predominant absorption route for both the interdigital (90 +/- 1%) and the abdomen (67 +/- 9%) injection sites. Fluorescein isothiocyanate dextran visualization studies revealed that the lymph draining the shoulder injection site entered the thoracic lymph duct distal to the point of cannulation, effectively precluding collection of thoracic lymph from this site. For that reason, the contribution of the lymphatics following injection in the shoulder could not be determined using these cannulation procedures.  相似文献   
34.
Accurate pregnancy dating is vital to obstetric management. However, first trimester fetal charts commonly used in Australia rely on data reported more than three decades ago. This study reports first trimester dating and growth charts for crown‐rump length between 5 and 14 weeks of gestation and biparietal diameter between 9 and 14 weeks of gestation on an Australia population using modern real‐time ultrasound equipment. All consenting eligible women attending a large Sydney clinic for first trimester ultrasound between March 2005 and December 2006 were recruited. Measurements were carried out to Australasian Society for Ultrasound in Medicine standard protocols. Statistical analyses were undertaken using polynomial regression models and thorough diagnostic checks made. Overall 396 eligible women consented to the study, with 268 between 9 and 14 weeks of gestation. The average participant age was 34 years (range 22–45 years), 371 and all yielded valid biometry measurements. Equations, means and 90% reference intervals for crown‐rump length measurements and biparietal diameter measurements were derived using polynomial regression models. Thorough residual and diagnostic checks were made. Once validated by others, we believe they will warrant consideration for use by Australasian Society for Ultrasound in Medicine.  相似文献   
35.
PURPOSE: To examine the effects of laser in situ keratomileusis (LASIK) for hyperopia on the tear film and ocular surface. METHODS: A retrospective 12-month analysis of 88 eyes (88 participants) who had LASIK for hyperopia was performed. Participants were evaluated before and after (2 weeks, 1, 3, 6, and 12 months) surgery for dry eye symptoms (McMonnies Dry Eye Survey primary symptoms), tear film stability (fluorescein break-up time), tear volume (phenol red thread test), ocular surface staining (fluorescein), and conjunctival goblet cell density. RESULTS: Chronic dry eye was experienced by 32% of participants; symptoms were significantly associated with female gender, preoperative dry eye symptoms, lower tear film stability after surgery, greater ocular surface staining after surgery, lower tear volume before and after surgery, and lower goblet cell densities after surgery. Regression rate 12 months after surgery was 32% and significantly associated with female gender, chronic dry eye symptoms, lower tear film stability after surgery, greater ocular surface staining before and after surgery, and lower tear volume before and after surgery. CONCLUSIONS: Dry eye, particularly in females, is problematic after LASIK for hyperopia and is associated with refractive regression. Current methods for managing the tear film and ocular surface may not control LASIK-induced dry eye, particularly in some females during the first 6 months after surgery.  相似文献   
36.
We present the study of colour duplex Doppler ultrasonography on Indian patients with non‐vasculogenic erectile dysfunction. Patients with a history suggestive of psychogenic impotence along with a normal clinical response to intracavernosal papaverine were presumed to have non‐vasculogenic erectile dysfunction. In our patients, the incidence of psychogenic impotence was much higher and the mean age of patients presenting with erectile dysfunction was lower as compared to patients from developed countries reported in research. The Doppler flowmetry showed much higher mean peak systolic velocities (PSVs) with a negative correlation between age and PSV. End diastolic velocity, resistive index and acceleration time values conformed to the literature.  相似文献   
37.
PURPOSE: To determine if the Arrow-Trerotola Percutaneous Thrombolytic Device (PTD) causes damage to normal vein valves. MATERIALS AND METHODS: Ten lateral saphenous veins in five dogs were studied with descending venography with use of a wedge balloon catheter positioned above 48 valves (demonstrating 51 valves) before and after five antegrade passes each with an over-the-wire (0.025-inch), 6.5-F, 9-mm-diameter PTD. Vein diameters were 3.2-11.4 mm (mean, 5.9 mm). Contrast matter was injected at incremental rates from 3 to 15 mL/min during continuous pressure monitoring. Imaging was performed with digital subtraction angiography at a rate of 1 frame/sec. The time to valve reflux was determined by noting the frame at which reflux was first seen through the valve. The time to reflux and pressure required to reflux were compared before and after the PTD passes. All vessels were explanted and evaluated histologically for presence or absence of endothelial loss, thrombus formation, inflammation, or valve degeneration. Four veins in two animals were studied with venography to determine the variability of the venographic method. These veins thrombosed during venography and therefore served as positive pathologic controls. In two animals, one vein was studied with venography and one was not studied to provide pathologic controls. RESULTS: With use of two physiologic tests of valve function, 77% of valves had minimal or no damage as assessed by valve competency and 80% had minimal or no damage as demonstrated by the change in the pressures the valve can withstand before reflux. Twenty-six of 51 valves (51%) had no difference or later reflux after PTD use. Thirteen (26%) refluxed 1 second earlier after PTD use and 12 (23%) refluxed > or =2 seconds earlier (six at 2, four at 3, and two at 4). Four of the six valves with more than a 2-second difference in reflux times were in valves with diameters less than 4.2 mm. All these vessels were smaller than 7 mm in diameter. Twenty-one of 48 valve levels (44%) had no difference or sustained higher pressures before reflux after PTD use. Seventeen (36%) had a pressure drop of <10 mm Hg; five (10%) had drops of 12-24 mm Hg; and five (10%) had drops of more than 40 mm Hg. There was a significant difference in endothelial loss, thrombus formation, and inflammation between experimental veins, the veins with thrombus, the venography controls, and the normal vein controls. There was significant difference only in terms of inflammation when the experimental group was compared to the thrombosis group. CONCLUSION: The antegrade use of the PTD across normal canine vein valves does not cause physiologically significant damage in valves 7 mm or larger in diameter in this animal model.  相似文献   
38.
39.
40.
Clinicians' management of children with psychosocial problems may vary with their attitudes and beliefs. However, we lack sound instruments to assess these factors. This study examined the psychometric properties of the Physician Belief Scale (PBS). A modified version of the PBS was sent to clinicians who participated in two primary care research networks. Using factor analysis, we reduced the PBS to 14 items and 2 subscales. Cronbach's alpha values were high. Female clinicians, those using DSM-IV, and those having completed training earlier rated themselves as more psychosocially oriented. Identification and treatment of psychosocial problems were significantly related to scores on the Belief and Feeling subscale. The PBS provided only a modest amount of information regarding primary care practices. It is not clear if these limitations are attributable to the instrument or the many other barriers to effective psychosocial care.  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