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   1444篇
  免费   63篇
  国内免费   4篇
耳鼻咽喉   2篇
儿科学   20篇
妇产科学   36篇
基础医学   205篇
口腔科学   71篇
临床医学   137篇
内科学   288篇
皮肤病学   41篇
神经病学   112篇
特种医学   130篇
外科学   172篇
综合类   16篇
预防医学   49篇
眼科学   72篇
药学   67篇
中国医学   4篇
肿瘤学   89篇
  2023年   4篇
  2022年   21篇
  2021年   25篇
  2020年   15篇
  2019年   18篇
  2018年   35篇
  2017年   17篇
  2016年   30篇
  2015年   52篇
  2014年   45篇
  2013年   63篇
  2012年   113篇
  2011年   108篇
  2010年   60篇
  2009年   74篇
  2008年   103篇
  2007年   96篇
  2006年   87篇
  2005年   101篇
  2004年   85篇
  2003年   89篇
  2002年   79篇
  2001年   17篇
  2000年   12篇
  1999年   23篇
  1998年   19篇
  1997年   22篇
  1996年   14篇
  1995年   13篇
  1994年   9篇
  1993年   8篇
  1992年   4篇
  1991年   2篇
  1990年   5篇
  1989年   2篇
  1988年   5篇
  1986年   2篇
  1983年   2篇
  1982年   6篇
  1981年   5篇
  1978年   3篇
  1976年   3篇
  1974年   2篇
  1972年   1篇
  1969年   1篇
  1968年   1篇
  1964年   1篇
  1962年   1篇
  1954年   1篇
  1937年   1篇
排序方式: 共有1511条查询结果,搜索用时 31 毫秒
991.
992.
BACKGROUND: Two single nucleotide polymorphisms (-13910 C/T and -22018 G/A) upstream of the lactase gene (LCT) have been found to be associated with lactose tolerance in Europeans. METHODS: In one hundred and twenty Austrian outpatients, who visited the physician's office for symptoms of irritable bowel syndrome (IBS), hydrogen breath testing (HBT) and LCT genotyping by polymerase chain reaction and reverse-hybridisation were performed in parallel. RESULTS: The coincidence between a genotype suggesting lactase non-persistence (lactose intolerance) and a positive HBT result was almost perfect (97.4% for LCT-13910 C/T and 100% for LCT-22018 G/A). Between a genotype indicating lactase persistence (lactose tolerance) and a negative HBT result the coincidence was lower (72% and 71.4%, respectively). Among heterozygotes, there was a statistically significant increase in the proportion of positive HBT results with age. Both SNPs were in accordance in 117/120 (97.5%) patients. CONCLUSION: Genetic analysis of LCT-13910 C/T and LCT-22018 G/A is a good indicator for the presence of lactose intolerance. Because age, as well as a number of secondary causes (e.g. celiac disease), can influence HBT results, it is useful to combine HBT and genetic analysis in the diagnostic assessment of IBS.  相似文献   
993.
Modulation of macrophage iron transport by Nramp1 (Slc11a1)   总被引:2,自引:0,他引:2  
  相似文献   
994.
Levels and activity of the enzyme estrogen sulfotransferase (EST) have been reported to play an important role in the regulation of in situ estrogen levels in human breast, prostate, and endometrial cancer. To better understand growth progression in endometrial stromal sarcomas (ESS), estrogen-dependent tumors, we analyzed the expression of EST in a series of 29 ESS. Archival formalin-fixed, paraffin-embedded material was analyzed immunohistochemically with a monoclonal antibody to EST using the peroxidase-antiperoxidase method. A score was calculated based on the percentage of positive tumor cells and staining intensity. EST staining was identified in 5 of 29 (18%) ESS and was scored as weakly positive, while 24 of 29 (82%) ESS were negative for EST. We demonstrate that a subset of ESS express EST, which may allow them to inactivate intratumoral estrogens. ESS without EST expression may have increased levels of biologically active estrogen, which explains the tumor progression of this entity and these patients may be at increased risk for recurrences and metastases.  相似文献   
995.
In order to enable a detailed analysis of radio frequency (RF) absorption in the human pineal gland, the dielectric properties of a sample of 20 freshly removed pineal glands were measured less than 20 h after death. Furthermore, a corresponding high resolution numerical model of the brain region surrounding the pineal gland was developed, based on a real human tissue sample. After inserting this model into a commercially available numerical head model, FDTD-based computations for exposure scenarios with generic models of handheld devices operated close to the head in the frequency range 400-1850 MHz were carried out. For typical output power values of real handheld mobile communication devices, the obtained results showed only very small amounts of absorbed RF power in the pineal gland when compared to SAR limits according to international safety standards. The highest absorption was found for the 400 MHz irradiation. In this case the RF power absorbed inside the pineal gland (organ mass 96 mg) was as low as 11 microW, when considering a device of 500 mW output power operated close to the ear. For typical mobile phone frequencies (900 MHz and 1850 MHz) and output power values (250 mW and 125 mW) the corresponding values of absorbed RF power in the pineal gland were found to be lower by a factor of 4.2 and 36, respectively. These results indicate that temperature-related biologically relevant effects on the pineal gland induced by the RF emissions of typical handheld mobile communication devices are unlikely.  相似文献   
996.
997.
998.
OBJECTIVE: To assess dynamic intraurethral sonography in the diagnostic evaluation of the function of the rhabdosphincter in female patients with urinary stress incontinence in relation to patient age. METHODS: Sixty-two patients with clinically proved urinary stress incontinence were investigated by means of intraurethral sonography with a 12.5-MHz endoluminal 9F catheter. The omega-shaped rhabdosphincter was visualized at rest and during voluntary contractions. Changes of muscle thickness and transducer-sphincter distance were measured and considered as parameters of muscle function. The intraurethral sonographic data were compared with results of standard urodynamic tests. RESULTS: Transducer-sphincter distance and sphincter muscle thickness showed a significant decrease with positive linear dependency on patient age (P < .001). Patients with grade III urinary stress incontinence had complete loss of sphincter contractility. A negative correlation was revealed between urethral closure pressure and patient age. CONCLUSIONS: We found an age-related decrease in rhabdosphincter function. Our results suggest that the rhabdosphincter is a substantial component of the continence mechanism in female urinary stress incontinence. Unlike urethral pressure profiles, which can only reveal zones of higher intraluminal pressure, transurethral sonography is highly specific for measurement of the function of the rhabdosphincter.  相似文献   
999.
PURPOSE: The aim of this study was to describe typical age-related sonographic features of the Achilles tendon and calcaneal apophysis in children, providing a reference for the assessment of heel pathologies during the growth period. METHODS: The calcaneal apophysis and Achilles tendon insertion of 100 children 2 months to 18 years old were examined by high-frequency gray-scale and color Doppler sonography along both the longitudinal and transverse planes. The thicknesses of the apophyseal cartilage at the calcaneal tuberosity and of the Achilles tendon were measured. Also, the sonographic appearance of the bone-cartilage interface was studied. RESULTS: In children 2 months to 3 years old, the cartilage of the calcaneal tuberosity apophysis was anechoic, with small scattered echoes. In 19 of these 25 children (76%), the echogenic areas contained at least 1 small vessel, visualized on color Doppler sonography. In 15 of 25 children (60%) 4-6 years old, a wavy interface was noted at the junction of the calcaneus and the apophyseal cartilage. CONCLUSIONS: High-frequency sonography can yield reliable information about the bone-cartilage interface and the Achilles tendon insertion site at the calcaneal tuberosity in children. The sonographic features of the normal heel described here may contribute to improved assessment of pathologies in this anatomic region.  相似文献   
1000.
We report the first documented case of human granulocytic ehrlichiosis (HGE) in Austria. The infection was acquired near Arzl in the surroundings of Innsbruck in northern Tyrol. Except for a biphasic course of illness, presentation in this 33-year-old female patient was comparable to clinical findings observed in other European adults with high fever, transient thrombocytopenia, elevated levels of CRP and LDH, arthralgias, myalgias, fatigue and subfebrile temperature. Flu-like symptoms started about seven days after a tick bite and lasted for ten days, followed by an asymptomatic interval of three days and an acute onset of fever up to 39.5 degrees C on day 20. On admission, the patient showed high antibody titres against Anaplasma phagocytophilum (IgG 1:1024, IgM 1:640); six weeks later the IgG-titre had risen to 1:2048, and IgM-levels had fallen below 1:40. The demonstration of anti-platelet antibodies in acute-phase serum was noteworthy. We conclude that also in Austria HGE should be considered in patients with febrile thrombocytopenia, especially when the medical history reveals recent tick exposure.  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