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   1211篇
  免费   92篇
  国内免费   8篇
耳鼻咽喉   9篇
儿科学   49篇
妇产科学   35篇
基础医学   173篇
口腔科学   18篇
临床医学   112篇
内科学   331篇
皮肤病学   26篇
神经病学   94篇
特种医学   15篇
外科学   89篇
综合类   10篇
预防医学   132篇
眼科学   22篇
药学   118篇
中国医学   8篇
肿瘤学   70篇
  2024年   1篇
  2023年   21篇
  2022年   54篇
  2021年   159篇
  2020年   54篇
  2019年   66篇
  2018年   71篇
  2017年   44篇
  2016年   52篇
  2015年   61篇
  2014年   47篇
  2013年   72篇
  2012年   103篇
  2011年   117篇
  2010年   43篇
  2009年   30篇
  2008年   51篇
  2007年   62篇
  2006年   38篇
  2005年   40篇
  2004年   39篇
  2003年   29篇
  2002年   30篇
  2001年   1篇
  1999年   2篇
  1998年   3篇
  1997年   4篇
  1996年   1篇
  1993年   2篇
  1992年   1篇
  1989年   1篇
  1988年   1篇
  1985年   1篇
  1984年   2篇
  1981年   2篇
  1980年   1篇
  1978年   2篇
  1977年   1篇
  1975年   2篇
排序方式: 共有1311条查询结果,搜索用时 93 毫秒
91.
Motor vehicle deaths in Hong Kong: opportunities for improvement   总被引:4,自引:0,他引:4  
OBJECTIVE: This study was undertaken to describe the epidemiology of motor vehicle mortality in Hong Kong, and to assess its impact on trauma service delivery. SETTING: Hong Kong has an area of 1,072 km2 and a population of 6,800,000. There were 500,000 registered vehicles in 2001. METHODS: All motor vehicle deaths must be reported to the coroner in Hong Kong. A manual retrospective review of all coroner case notes involving motor vehicles for 2001 was performed. RESULTS: The review identified 165 cases involving 111 male and 54 female patients. Elderly cases were predominant, with 37% of the cases involving individuals older than 60 years. Most of the cases involved pedestrians (59%), and half of these pedestrians had experienced collisions with public light buses and trucks. Alcohol was not commonly involved, and when it was, it was isolated to the group 20 to 40 years of age. Most individuals died of major head injury alone or multiple injuries. There were very few major vessel injuries, and these included 13 aortic transections. DISCUSSION: Hong Kong has a very low motor vehicle death rate relative to its population (2.4 per 100,000), but the rate is less impressive when it is related to motor vehicle registrations (33 per 100,000 vehicles). The low incidence of motor vehicle trauma has implications for trauma service delivery in terms of trauma expertise and specialization. Despite the low incidence of trauma, there still are opportunities for prevention, especially in relation to elderly pedestrians and public light buses.  相似文献   
92.
BACKGROUND: The mucopolysaccharidosis (MPS) are a group of inherited metabolic disorders resulting from the deficiency of the enzyme responsible for intralysosomal catabolism of glycosaminoglycans (GAGs). GAGs are progressively accumulated in multiple tissues and released into the corporal fluids. The first laboratory approximation to MPS diagnosis is the identification of an increased urinary GAG excretion. For this, several semiquantitative and quantitative methods have been developed. The aim of this retrospective statistical study was to evaluate the reliability of MPS urine screening for the semiquantitative Berry spot test (BST) and the quantitative dimethylmethylene blue test (DMB). METHODS: The 24-h-urine samples (n = 246) were tested through BST, DMB, and for GAG excretion pattern by one-dimensional electrophoresis or thin layer chromatography. RESULTS: the 204 samples that demonstrated a normal GAG excretion pattern were considered as non-MPS samples. Forty-two samples presented an abnormal GAG excretion pattern. Enzyme analysis was available for 31 out of 42 patients (31/42), confirming that all were affected by MPS. Urinary GAG concentrations of MPS patients by DMB were increased 1.04- to 7.1-folds, compared to age-related normal levels. The sensitivity was 100% for DMB and 93.6% for BST. DMB demonstrated a specificity of 74.5%, while BST a specificity of 53.9%. The specificity of MPS screening increased to 84.3%, considering conjunctly DMB and BST. CONCLUSION: The DMB is a sensitive method, however, inclusion of BST could increase the specificity of MPS urine screening.  相似文献   
93.
Air pollution standards and control strategies are based on ambient measurements. For many outdoor air pollutants, individuals are closer to their sources (especially traffic) and there are important indoor sources influencing the relationship between ambient and personal exposures. This paper examines the relationship between volatile organic compounds (VOCs) measured at central site monitoring stations and personal exposures in the Mexico City Metropolitan Area. Over a 1-year period, personal exposures to 34 VOCs were measured for 90 volunteers from 30 families living close to one of five central monitoring stations. Simultaneous 24-h indoor, outdoor and central site measurements were also taken. Dual packed thermal desorption tubes and C(18) DNPH-coated cartridges were used for sampling VOCs and these were analyzed by GC/MS and HPLC, respectively. A factor analysis of the personal exposure data aided in grouping compounds by the most likely source type: vehicular (BTEX, styrene and 1,3-butadiene), secondary formed or photochemical (most aldehydes), building materials and consumer products (formaldehyde and benzaldehyde), cleaning solvents (tetrachloroethene and 1,1,1-trichloroethane), volatilization from water (chloroform and trichloroethene) and deodorizers (1,4-dichlorobenzene). Mean ambient, indoor and personal concentrations were 7/7/14 microg/m(3) for benzene, 1/3/3 for 1,3-butadiene, 6/20/20 for formaldehyde and 3/9/50 for 1,4-dichlorobenzene. Geometric mean (GM) ambient concentrations of trichloroethene and carbon tetrachloride were similar to GM personal exposures. While outdoor and indoor home GM concentrations for most vehicular related compounds (benzene, MTBE, xylenes and styrene) were comparable, the GM personal exposures were twice as high. Indoor concentrations of 1,3-butadiene, 1,1,1-trichloroethane, tetrachloroethane, chloroform, formaldehyde, valeraldehyde, propionaldehyde and n-butyraldehyde were comparable to personal exposures. For certain compounds, such as chloroform, aldehydes, toluene, 1,3-butadiene and 1,4-dichlorobenzene, GM personal exposures were more than two times greater than GM ambient measurements.  相似文献   
94.
95.
In this paper we show that 4-aryl-CH2-imidazole-substituted benzopyran compounds with 3S,4R-stereochemistry are cardioprotective by inhibiting the F1F0 mitochondrial ATP hydrolase. Compounds (e.g., 13) with 3R,4S-stereochemistry act as mitochondrial KATP openers. This resulted from an inversion of stereochemistry for the F1F0 mitochondrial ATP hydrolase vs mitochondrial KATP. Structure-activity relationships for the inhibition of mitochondrial ATP hydrolase are also delineated. It is not clear how 13 (3R,4S) can selectively inhibit the hydrolytic activity of the F1F0 mitochondrial enzyme without interfering with the synthase activity.  相似文献   
96.
In the present study, we investigated the [(3)H]citalopram binding using a quantitative autoradiography following intracerebroventricular injection of 5,7-dihydroxytryptamine (5,7-DHT) in neonatal and adult male Wistar rats. One group of animals was injected with 5,7-DHT at 3 days after birth while the second group received the neurotoxin at 3 months after birth. Control group was injected with saline. Afterwards, all rats were examined at 4(th) months after birth to determine the serotonin (5-HT) and catecholamines concentrations using the liquid chromatography with electrochemical detection HPLC system and distribution and density of [(3)H]citalopram binding sites in the brain using the quantitative autoradiography. A marked depletion of brain 5-HT was observed in rats lesioned either in postnatal or adult period of life. Rats lesioned in their adult period of life showed dramatic reduction of 5-HT transporter in all investigated brain areas (i.e.the frontal cortex, entorhinal cortex, hippocampus, caudate-putamen, nucleus accumbens and ventral tegmental area). On the other hand, administration of 5,7-DHT to newborn rats failed to reduce 5-HT transporter sites in the ventral tegmental area, and produced only slight or moderate reduction in the nucleus accumbens. Thus, it appears that the mesolimbic ventral tegmental area-nucleus accumbens systems are relatively more resistant to 5,7-DHT neurotoxicity in the early postnatal period.  相似文献   
97.
Abstract: Objective: To examine the efficacy and safety of using continuous subcutaneous insulin infusion (CSII) therapy in a large group of patients 18 months to 18 yr from a single pediatric diabetes program. Research design and methods: All patients ≤ 18 yr of age starting on CSII from 1 January 1997 to 31 March 2000 at the Yale Children's Diabetes Program were included. Clinical data were collected prospectively before and during pump treatment. HbA1c was the primary efficacy outcome and rates of diabetes‐related adverse events were the primary safety measures. Results: One hundred and sixty‐one children ranging in age from 18 months to 18 yr received CSII for an average of 32 ± 9 months when data collection was closed on 31 October 2001, including 26 preschoolers (< 7 yr), 76 school‐agers (7–11 yr) and 59 adolescents (12–18 yr). Mean HbA1c levels were 7.1% in the preschoolers, 7.8% in the school‐agers and 8.1% in the adolescents prior to the start of CSII. There was a significant and consistent reduction in mean HbA1c levels after 12 months of CSII (to 6.5% in preschoolers, 7.3% in school‐agers and 7.4% in adolescents, p < 0.02 vs. prepump) that was maintained at the most recent visit. Improved diabetes control was achieved with CSII without increasing daily insulin doses and in association with a decrease in the frequency of severe hypoglycemic events (p < 0.05 vs. prepump, all three age groups combined). Conclusions: CSII is an effective alternative to injection therapy in a large pediatric diabetes clinic setting. Even very young patients can utilize CSII to safely lower HbA1c levels.  相似文献   
98.
The contributions of cytochrome P450 3A (CYP3A) and P-glycoprotein to sirolimus oral bioavailability in rats were evaluated by coadministration of sirolimus (Rapamune) with the CYP3A inhibitor ketoconazole or the P-glycoprotein inhibitor D-alpha-tocopheryl poly(ethylene glycol 1000) succinate (TPGS). Groups of six male Sprague-Dawley rats (250-300 g) were administered Rapamune (1 mg/kg) by oral gavage, alone and with ketoconazole (30 mg/kg) or TPGS (50 mg/kg). Sirolimus levels were measured in whole blood over a 6-h time course. Sirolimus C(max) (6.6 +/- 1.6 versus 26 +/- 7 ng/ml) and area under the concentration versus time curve from 0 to 6 h (AUC(0-6)) (22 +/- 7 versus 105 +/- 27 ng. h/ml) were increased 3- to 5-fold by ketoconazole. Median T(max) (1.5-2 h) was unchanged. TPGS had no effect on sirolimus absorption. The interaction of sirolimus with P-glycoprotein was also evaluated in vitro using HCT-8 and Caco-2 cell monolayers. Consistent with published reports, sirolimus was a good inhibitor of P-glycoprotein, inhibiting polarized basolateral-to-apical flux of rhodamine 123 with an IC(50) of 0.625 to 1.25 microM (cyclosporine caused >80% inhibition at 5 microM). Sirolimus did not demonstrate significant polarized flux in either direction using the same monolayers (basolateral-to-apical flux was <2 times the apical-to-basolateral). Moreover, sirolimus flux was not impacted by cyclosporine, suggesting that it does not undergo P-glycoprotein-mediated transport in this system. The lack of significant sirolimus transport by P-glycoprotein may, in part, explain the lack of a TPGS effect on sirolimus absorption in rats.  相似文献   
99.
Acute lymphocytic leukemia developed within 3 weeks after a fulminant case of varicella complicated by pneumococcal sepsis and severe bone marrow suppression in a child treated with filgrastim (human granulocyte colony-stimulating factor).  相似文献   
100.
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