首页 | 官方网站   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   4567篇
  免费   204篇
  国内免费   38篇
医药卫生   4809篇
  2023年   37篇
  2022年   52篇
  2021年   100篇
  2020年   52篇
  2019年   78篇
  2018年   102篇
  2017年   72篇
  2016年   77篇
  2015年   94篇
  2014年   115篇
  2013年   147篇
  2012年   220篇
  2011年   253篇
  2010年   151篇
  2009年   126篇
  2008年   177篇
  2007年   163篇
  2006年   187篇
  2005年   191篇
  2004年   206篇
  2003年   182篇
  2002年   204篇
  2001年   193篇
  2000年   187篇
  1999年   164篇
  1998年   54篇
  1997年   32篇
  1996年   38篇
  1995年   39篇
  1994年   28篇
  1993年   25篇
  1992年   101篇
  1991年   107篇
  1990年   91篇
  1989年   90篇
  1988年   76篇
  1987年   75篇
  1986年   79篇
  1985年   60篇
  1984年   36篇
  1983年   46篇
  1979年   28篇
  1978年   22篇
  1977年   29篇
  1975年   19篇
  1973年   24篇
  1972年   19篇
  1968年   17篇
  1967年   15篇
  1966年   17篇
排序方式: 共有4809条查询结果,搜索用时 0 毫秒
1.
High blood pressure (BP) is a major determinant of cardiovascular events in obesity. The beta2- and beta3-adrenoceptor polymorphisms are associated with obesity and hypertension. In the present study, we examine the relationships of beta2- and beta3-adrenoceptor polymorphisms with further weight gain-induced BP elevation in obese subjects. Changes in BP, body weight, total body fat-mass, waist-to-hip ratio, plasma norepinephrine (NE) and leptin levels, and beta2(Arg16Gly)- and beta3(Trp64Arg)-adrenoceptor polymorphisms were measured periodically over a 5-year period in 55 entry obese (body mass index [BMI]> or =25.0 kg/m(2)) normotensive (BP<140/90 mmHg) men. BP elevation and weight gain were defined as > or =10% increases from entry levels over 5 years in mean BP or BMI. Obese subjects with weight gain, BP elevation or weight gain-induced BP elevation had higher frequencies of the Gly16 allele of Arg16GIy and Arg64 allele of Trp64Arg. Subjects carrying the Gly16 or Arg64 alleles had significantly greater total fat-mass and waist-to-hip ratio at entry and over a 5-year period compared to the subjects who did not carry these polymorphisms. Subjects carrying the Gly16 allele had similar levels of plasma NE, higher levels of plasma leptin and a lower slope of the regression lines between plasma leptin and NE levels. Those carrying the Arg64 allele had higher plasma NE levels at entry and over a 5-year period compared to the subjects without the Arg64 allele, but plasma leptin levels and slopes were similar. The findings demonstrate that the Arg64 allele of the beta3-adrenoceptor polymorphisms relates to weight gain-induced BP elevation accompanying high plasma NE (heightened sympathetic activity) in obese men. The Gly16 allele of the beta2-adrenoceptor polymorphisms links to weight gain-induced BP elevation associated with leptin resistance. beta2- and beta3-adrenoceptor polymorphisms could predict the future BP elevation and further weight gain-induced BP elevation in originally obese subjects.  相似文献   
2.
3.
Mammalian bones have three distinct origins (paraxial mesoderm, lateral plate mesoderm, and neural crest) and undergo two different modes of formation (intra-membranous and endochondral). Bones derived from the paraxial mesoderm and lateral plate mesoderm mainly form through the endochondral process. During this process, hypertrophic chondrocytes play a vital role in inducing both osteogenesis and angiogenesis. One of the essential osteogenic factors secreted from hypertrophic chondrocytes is Indian hedgehog (Ihh). In contrast, bones derived from the neural crest mainly form through the intramembranous pro-cess and do not require Ihh. Thus, depending on their origin, bones have distinct signaling properties, which need to be considered in the research and application of bone biology.Presented at the 18th Annual Research Meeting of the Japanese Orthopaedic Association, Kitakyushu, Japan, October 17, 2003  相似文献   
4.
5.
A case of Beh?et disease associated with aortic valve regurgitation treated with aortic valve replacement is reported. The patient was treated successfully with special surgical techniques for prevention of post operative paravalvular leakage and occurrence of pseudo aneurysm because the patient was under long-term steroid therapy for Beh?et disease.  相似文献   
6.
Ontogenesis of the cerebellofugal projection was studied in the rat by the tract-tracing method with WGA-HRP. The projection, forming a uniform front of compact fibre bundle tipped by growth cones, began entering the brainstem on embryonic day 17 (E17), grew rapidly and orderly with no random extension of fibers, and arrived at the most rostral part of the thalamus already by E18, distributing dense terminals to various brainstem and thalamic nuclei. The course and termination of this projection in prenatal animals was largely similar to normal adult projection although differences were found. Some projections increased postnatally, whereas some projections which were existent in embryos regressed with age and finally disappeared completely. The adult pattern of the projection was attained by 3 weeks of age. It is worth noting that the projections which appeared transiently are similar to those reported as aberrantly regenerated projections in kittens which are born in more mature state than rats and have no such projections at birth.  相似文献   
7.
Ester prodrugs of zidovudine   总被引:1,自引:0,他引:1  
Ten novel ester prodrugs of zidovudine (azidothymidine; AZT) were synthesized with aliphatic acids (acetic-stearic), and the enzymatic regeneration of AZT from the prodrugs was investigated both in vitro and in vivo. The enzymatic hydrolysis rates of the AZT esters in the presence of mouse enzyme systems (plasma, liver, and intestine, and kidney) were highly dependent on the lengths of the acyl chains of the prodrugs. The caprate or caprylate of AZT showed the highest reactivity to three of the four enzyme systems; either the decrease or the increase in the acyl chain length resulted in the decrease of the reactivity to the enzymes. Zidovudine (AZT) and three of the prodrugs (acetate, caprate, and stearate) were administered to mice intraperitoneally, and the plasma concentrations of AZT and a corresponding prodrug were measured. The AZT concentrations in plasma following the acetate administration rapidly decreased with a half-life of 14.5 min. This tendency is similar to that shown in direct AZT administration. On the other hand, the concentrations following the caprate or stearate administration decreased slowly and were maintained for as long as 4 h after dosing. The prodrug concentrations in plasma after the prodrug administration were under the detection limit (0.01 micrograms/mL), except for acetate. The absence of the caprate and stearate in plasma may be attributed to the high hydrophobicity or favorable tissue distribution of the ester derivatives.  相似文献   
8.
9.
IL-17 family members belong to a distinct category of cytokines that coordinate local tissue inflammation by inducing the release of pro-inflammatory and neutrophil-mobilizing cytokines. The importance of the IL-17 family in inflammatory and autoimmune disease is becoming increasingly apparent. IL-17F is a recently discovered member of the IL-17 family that has a number of biological activities through induction of various cytokines, chemokines, and mediators. IL-17A, the founding member of the IL-17 family, and IL-17F are produced by several inflammatory cells, including activated T cells, in response to infectious and antigenic stimuli. Overexpression of IL-17A or IL-17F in the lungs results in induction of CXC chemokines and neutrophil recruitment. In a case-control study of 1125 unrelated Japanese subjects, a His161 to Arg161 (H161R) substitution in the third exon of the IL17F gene was shown to be associated with asthma and chronic obstructive pulmonary disease (COPD). Functionally, this variant failed to induce cytokines and chemokines, and interestingly, was able to antagonize the activity of wild-type IL-17F. These results provide an experimental basis for the observed genetic association with chronic inflammatory lung diseases, and also suggest the potential therapeutic utility of this antagonistic variant of IL-17F. Given that asthma and COPD are complex diseases involving a number of genetic and environmental factors, the genetic impact of IL-17F H161R with regard to the development of chronic airway inflammation likely varies among individuals with different genetic backgrounds and environmental exposures.  相似文献   
10.
We assessed the local cerebral blood flow (LCBF) in 40 patients under fentanyl-diazepam anesthesia. The measurement of LCBF was made using 50%–70% stable xenon with 20 min of inhalation interval and a shuttle method for computed tomography imaging. All patients were anesthetized with 5.95±1.76 μg·kg−1 fentanyl and 0.22±0.07 mg·kg−1 diazepam under mechanical ventilation during CBF measurement. The values and distribution of LCBF on non-affected hemisphere appeared to be unaltered by fentanyldiazepam anesthesia. We also assessed the cerebral carbon dioxide reactivity in 6 patients. The cerebral carbon dioxide reactivity, expressed as percentage change in LCBF per unit change in arterial carbon dioxide partial pressure, was 5.39±1.07, and there were no significant differences of reactivity among regions studied. In conclusion, we showed reference values of LCBF and carbon dioxide reactivity, measured by stable xenon-enhanced computed tomography, in patients under fentanyl-diazepam anesthesia. Carbon dioxide reactivity was preserved in all regions including gray matter, white matter, and basal ganglia.  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-23

京公网安备 11010802026262号