全文获取类型
收费全文 | 10358篇 |
免费 | 735篇 |
国内免费 | 40篇 |
专业分类
耳鼻咽喉 | 55篇 |
儿科学 | 322篇 |
妇产科学 | 146篇 |
基础医学 | 1482篇 |
口腔科学 | 309篇 |
临床医学 | 979篇 |
内科学 | 2319篇 |
皮肤病学 | 115篇 |
神经病学 | 1123篇 |
特种医学 | 463篇 |
外科学 | 1577篇 |
综合类 | 64篇 |
一般理论 | 3篇 |
预防医学 | 590篇 |
眼科学 | 129篇 |
药学 | 836篇 |
中国医学 | 11篇 |
肿瘤学 | 610篇 |
出版年
2023年 | 56篇 |
2022年 | 91篇 |
2021年 | 199篇 |
2020年 | 144篇 |
2019年 | 204篇 |
2018年 | 246篇 |
2017年 | 224篇 |
2016年 | 222篇 |
2015年 | 211篇 |
2014年 | 322篇 |
2013年 | 437篇 |
2012年 | 662篇 |
2011年 | 640篇 |
2010年 | 369篇 |
2009年 | 334篇 |
2008年 | 631篇 |
2007年 | 585篇 |
2006年 | 525篇 |
2005年 | 529篇 |
2004年 | 457篇 |
2003年 | 467篇 |
2002年 | 400篇 |
2001年 | 248篇 |
2000年 | 203篇 |
1999年 | 226篇 |
1998年 | 147篇 |
1997年 | 97篇 |
1996年 | 111篇 |
1995年 | 90篇 |
1994年 | 77篇 |
1993年 | 85篇 |
1992年 | 159篇 |
1991年 | 160篇 |
1990年 | 145篇 |
1989年 | 174篇 |
1988年 | 134篇 |
1987年 | 135篇 |
1986年 | 136篇 |
1985年 | 111篇 |
1984年 | 93篇 |
1983年 | 72篇 |
1982年 | 56篇 |
1981年 | 48篇 |
1980年 | 47篇 |
1979年 | 67篇 |
1978年 | 44篇 |
1977年 | 35篇 |
1976年 | 32篇 |
1973年 | 37篇 |
1971年 | 31篇 |
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
1.
Madan M. Rehani Emily R. Melick Raza M. Alvi Ruhani Doda Khera Salma Batool-Anwar Tomas G. Neilan Michael Bettmann 《European radiology》2020,30(4):1839-1846
To determine percent of patients without malignancy and ≤ 40 years of age with high cumulative radiation doses through recurrent CT exams and assess imaging appropriateness. From the cohort of patients who received cumulative effective dose (CED) of ≥ 100 mSv over a 5-year period, a sub-set was identified with non-malignant disease. The top 50 clinical indications leading to multiple CTs were determined. Clinical decision support (CDS) system scores were analyzed using a widely adopted standard of 1–3 (red) as “not usually appropriate,” 4–6 (yellow) “may or may not be appropriate,” and 7–9 (green) “usually appropriate.” Clinicians reviewed patient records to assess compliance with appropriate use criteria (AUC). 9.6% of patients in our series were with non-malignant conditions and 1.4% with age ≤ 40 years. CDS scores (rounded) were 2% red, 38% yellow, 27% green, and 33% unscored CTs. Clinical society guidelines for CT exams, wherever available, were followed in 87.5 to 100% of cases. AUCs were not available for several clinical indications as also referral guidelines for serial CT imaging. More than half of CT exams were unrelated to follow-up of a primary chronic disease. We are faced with a situation wherein patients in age ≤ 40 years require or are thought to require many CT exams over the course of a few years but the radiation risk creates concern. There is a fair number of conditions for which AUC are not available. Suggested solutions include development of CT scanners with lesser radiation dose and further development of appropriateness criteria. 相似文献
2.
3.
Sergue? O Fetissov Jarmila Hallman Ida Nilsson Ann-Kari Lefvert Lars Oreland Tomas H?kfelt 《Neuropsychopharmacology》2006,60(8):799-802
BACKGROUND: Altered stress response is characteristic for subjects with abnormal aggressive and antisocial behavior, but the underlying biological mechanisms are unclear. We hypothesized that autoantibodies (autoAbs) directed against several stress-related neurohormones may exist in aggressive subjects. METHODS: Using enzyme-linked immunosorbent assay, we studied whether autoAbs directed against corticotropin (ACTH), alpha-melanocyte-stimulating hormone (alpha-MSH), oxytocin, and vasopressin are present in serum of male subjects with conduct disorder and prisoners with history of violence. Healthy blood donors served as control subjects. RESULTS: Both conduct disorder and prisoners groups displayed strongly increased levels of ACTH-reactive immunoglobulin G (IgG) and immunoglobulin M (IgM) autoAbs compared with control subjects. Levels of oxytocin-reactive IgM autoAbs were slightly increased in both groups of aggressive subjects, whereas levels of vasopressin-reactive IgG and IgM autoAbs were lower only in conduct disorder. No differences in the levels of alpha-MSH-reactive autoAbs were found between aggressive and control subjects. CONCLUSIONS: High levels of ACTH-reactive autoAbs as well as altered levels of oxytocin- and vasopressin-reactive autoAbs found in aggressive subjects may interfere with the neuroendocrine mechanisms of stress and motivated behavior. Our data suggest a new biological mechanism of human aggressive behavior that involves autoAbs directed against several stress-related neurohormones. 相似文献
4.
Olle Zetterström Christer Andersson Leif Eriksson ers Fredriksson Johan Friskopp Gunnar Heden Bernt Jansson Tord Lundgren Rolf Nilveus ers Olsson Stefan Renvert Lars Salonen Lars Sjöström ers Winell ers Östgren Stina Gestrelius 《Journal of clinical periodontology》1997,24(9):697-704
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
5.
The effects of repeated doses of benzodiazepines, diazepam and midazolam in combination with meperidine on arterial blood gases and transcutaneous PO2 were studied in eight healthy volunteers. The study was designed to mimic a clinical situation. Initially two doses of either midazolam 0.05 mg/kg or diazepam in fat emulsion 0.15 mg/kg were given in a randomized crossover fashion with a 20-min interval, followed by meperidine 0.5 mg/kg another 20 min later. The opioid effects were then antagonized by naloxone 0.4 mg. The initial doses of benzodiazepines caused an increase in PaCO2 and a decrease in PaO2. The changes in PaO2 were of short duration and recovered to baseline levels between injections. However, they came sooner and were more pronounced after midazolam. The changes in PtcO2 paralleled those in PaO2. The PtcO2 index as a measure of cardiac output and peripheral blood flow adequacy was increased immediately after the first injection of midazolam but was otherwise not different from control. There were no differences between the drugs concerning PtcO2 index. PaCO2 increased after the first benzodiazepine injection and remained so throughout the study. Addition of meperidine caused only small changes in PaO2 and PaCO2. These changes were reversed by naloxone. In spite of different elimination kinetics there was no difference in the duration of respiratory depression between the two benzodiazepines. 相似文献
6.
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
7.
8.
9.
We would like to thank Professor Erdem Kasikcioglu for his interestin our article. In response to the initial question of why exhaustivephysical activity suppresses diastolic function, 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