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   14992篇
  免费   900篇
  国内免费   45篇
耳鼻咽喉   141篇
儿科学   533篇
妇产科学   261篇
基础医学   1933篇
口腔科学   403篇
临床医学   1555篇
内科学   3035篇
皮肤病学   136篇
神经病学   1565篇
特种医学   592篇
外科学   1973篇
综合类   76篇
一般理论   6篇
预防医学   1161篇
眼科学   233篇
药学   1236篇
中国医学   28篇
肿瘤学   1070篇
  2023年   63篇
  2022年   96篇
  2021年   191篇
  2020年   190篇
  2019年   246篇
  2018年   304篇
  2017年   273篇
  2016年   294篇
  2015年   290篇
  2014年   370篇
  2013年   712篇
  2012年   859篇
  2011年   842篇
  2010年   521篇
  2009年   482篇
  2008年   869篇
  2007年   856篇
  2006年   847篇
  2005年   817篇
  2004年   768篇
  2003年   761篇
  2002年   689篇
  2001年   312篇
  2000年   238篇
  1999年   287篇
  1998年   201篇
  1997年   171篇
  1996年   173篇
  1995年   166篇
  1994年   139篇
  1993年   153篇
  1992年   208篇
  1991年   215篇
  1990年   181篇
  1989年   215篇
  1988年   172篇
  1987年   166篇
  1986年   158篇
  1985年   139篇
  1984年   154篇
  1983年   107篇
  1982年   121篇
  1981年   108篇
  1980年   67篇
  1979年   83篇
  1978年   71篇
  1977年   82篇
  1976年   56篇
  1975年   56篇
  1971年   54篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Tamoxifen prevents recurrence of breast cancer and is suggested for preventive risk-reducing therapy. Tamoxifen reduces mammographic density, a proxy for therapy response, but little is known about its effects in remodelling normal breast tissue. Our study, a substudy within the double-blinded dose-determination trial KARISMA, investigated tamoxifen-specific changes in breast tissue composition and histological markers in healthy women. We included 83 healthy women randomised to 6 months daily intake of 20, 10, 5, 2.5, 1 mg of tamoxifen or placebo. The groups were combined to “no dose” (0-1 mg), “low-dose” (2.5-5 mg) or “high-dose” (10-20 mg) of tamoxifen. Ultrasound-guided biopsies were collected before and after tamoxifen exposure. In each biopsy, epithelial, stromal and adipose tissues was quantified, and expression of epithelial and stromal Ki67, oestrogen receptor (ER) and progesterone receptor (PR) analysed. Mammographic density using STRATUS was measured at baseline and end-of-tamoxifen-exposure. We found that different doses of tamoxifen reduced mammographic density and glandular-epithelial area in premenopausal women and associated with reduced epithelium and increased adipose tissue. High-dose tamoxifen also decreased epithelial ER and PR expressions in premenopausal women. Premenopausal women with the greatest reduction in proliferation also had the greatest epithelial reduction. In postmenopausal women, high-dose tamoxifen decreased the epithelial area with no measurable density decrease. Tamoxifen at both low and high doses influences breast tissue composition and expression of histological markers in the normal breast. Our findings connect epithelial proliferation with tissue remodelling in premenopausal women and provide novel insights to understanding biological mechanisms of primary prevention with tamoxifen.  相似文献   
2.
3.
4.
OBJECTIVE: Analysis of the effects of a comprehensive focal spasticity program in adult patients. DESIGN: Retrospective study of an out-patient cohort. PATIENTS: One hundred patients were enrolled in the study (54 men and 46 women, mean age 41 years (SD 14). Cerebral palsy and stroke were equally common (80% in total). The remaining patients had miscellaneous diagnoses, including traumatic brain injury. METHODS: On average 230 units (SD 101) of botulinum toxin A Botox was given for 227 principal therapy targets chosen by the patient or the caregiver. One patient could have several targets for therapy. Administration of botulinum toxin was combined with 260 additional therapeutic interventions, most of which were forms of physical therapy. The effects were assessed after 6 weeks and compared with baseline functional abilities 1-2 weeks prior to therapy. RESULTS: Improvement was observed for 211 (93%) therapy targets, no change in 15 (7%), and impairment in 1, corresponding to an overall improvement in 90 patients (90%), 9 unchanged (9%) and worsening in 1. Spasticity assessment (Ashworth scale 0-4; 30 patients) showed a statistically significant improvement (median at baseline was 3 vs 2 after therapy, mean difference 1.2, p<0.001). CONCLUSION: Improvement was observed in >or=90% of patients and in their principal therapeutic targets in a cohort receiving their first focal spasticity treatment with botulinum toxin A and additional therapy. A strict strategy for patient selection and comprehensive management was followed.  相似文献   
5.
Abstract The aim of the present clinical trial was to test tolerability during 2 treatments with EMDOGAIN® in a large number of patients. An open, controlled study design in 10 Swedish specialist clinics was chosen, with a test group of 107 patients treated with EMDOGAIN® in connection with periodontal surgery at 2 surgical test sites per patient. The procedures were performed 2 to 6 weeks apart on one-rooted teeth with at least 4 mm deep intraosseous lesions. A control group of 33 patients underwent flap surgery without EMDOGAIN® at I comparable site. In total 214 test and 33 control surgeries were performed. Serum samples were obtained from test patients for analysis of total and specific antibody levels. 10 of the patients had samples taken before and after the first surgery. 56 other samples were taken after one treatment with EMDOGAIN®, and 63 after 2 treatments. None of the samples, not even from allergy-prone patients after 2 treatments, indicated deviations from established baseline ranges. This indicates that the immunogenic potential of EMDOGAIN® is extremely low when applied in conjunction with periodontal surgery. Comparison between the test and control groups demonstrated the same type and frequency of post-surgical experiences, i.e., reactions caused by the surgical procedure itself. Clinical probing and radiographic evaluation was performed at baseline and 8 months postsurgery. About half of the patients (44 test and 21 control) were also evaluated after 3 years. There was a significant difference between the test and control results at 8 months post surgery. and this difference had increased further at the 3 year follow-up. The 2.5–3 mm increase in attachment and bone level after treatment with EMDOGAIN® was of the same magnitude as seen in the studies with split-mouth design aiming for lest of effectiveness of EMDOGAIN®.  相似文献   
6.
7.
Using the buttock flap in 29 white Yorkshire pigs, blood flow and O2 consumption were measured at dermal temperatures between 35 degrees C and 15 degrees C. Flow was measured with an electromagnetic flowmeter and O2 consumption was calculated as the product of blood flow and the difference in flap A-VO2. Baseline flow was 6.6 +/- .9 (SE) ml/100 g/min at 35 degrees C and 3.1 +/- .02 (SE) ml/10 g/min at 15 degrees C. Blood flow through the flap stopped completely at a dermal temperature of 14 degrees C. Oxygen consumption was 0.16 +/- .02 (SE) ml/100 g/min at 35 degrees C and 0.04 +/- 0.01 (SE) ml/100 g/min at 15 degrees C. At 20 degrees C blood flow was 4.3 ml/100 g/min and metabolism was .04 ml/100 g/min. In other words, blood flow was 65% of baseline, while O2 consumption was only 25% of baseline. The therapeutic effect of local cooling at 20 degrees C deserves further investigation. The cessation of flow at 14 degrees C may be caused by increased plasma viscosity.  相似文献   
8.
9.

Background  

It is well known that physicians' night-call duty may cause impaired performance and adverse effects on subjective health, but there is limited knowledge about effects on sleep duration and recovery time. In recent years occupational stress and impaired well-being among anaesthesiologists have been frequently reported for in the scientific literature. Given their main focus on handling patients with life-threatening conditions, when on call, one might expect sleep and recovery to be negatively affected by work, especially in this specialist group. The aim of the present study was to examine whether a 16-hour night-call schedule allowed for sufficient recovery in anaesthesiologists compared with other physician specialists handling less life-threatening conditions, when on call.  相似文献   
10.
Urticaria is a common condition, seldom of allergic origin. It is however not always possible to find the provoking allergen. The aim of the present study was to analyze if there was a relationship between urticaria and sensitization to common airborne allergens. A representative sample of 402 12 to 13-yr-old children answered a questionnaire on allergic diseases, 397 were interviewed by the study nurse and 371 underwent skin prick tests to cat, dog, horse, birch, timothy-grass, house dust mites and Cladosporium mould. Specific IgE-antibodies were analyzed to birch pollen and cat dander. Urticaria was more common in sensitized children, but the relationship between urticaria and sensitization was only statistically significant for birch pollen sensitization (OR 1.99, 95% CL 1.04-3.83), when tested in a multiple logistic regression model with the specified allergens as independent variables. A similar pattern was seen for birch-specific IgE-antibody levels, which was higher in children reporting urticaria than in those without. IgE-levels to cat dander did not show such a difference. Urticaria was statistically significantly associated with sensitization to birch-pollen, but not to other common inhalant allergens. We propose that intake of birch-pollen cross-reactive food-stuffs may be a neglected cause of urticaria and relapsing urticaria, in birch-pollen sensitized subjects.  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