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   4311篇
  免费   298篇
  国内免费   32篇
耳鼻咽喉   29篇
儿科学   105篇
妇产科学   96篇
基础医学   496篇
口腔科学   209篇
临床医学   376篇
内科学   1183篇
皮肤病学   44篇
神经病学   572篇
特种医学   97篇
外科学   423篇
综合类   12篇
预防医学   310篇
眼科学   17篇
药学   284篇
中国医学   6篇
肿瘤学   382篇
  2024年   8篇
  2023年   63篇
  2022年   106篇
  2021年   186篇
  2020年   100篇
  2019年   121篇
  2018年   151篇
  2017年   125篇
  2016年   124篇
  2015年   158篇
  2014年   179篇
  2013年   226篇
  2012年   361篇
  2011年   335篇
  2010年   168篇
  2009年   166篇
  2008年   271篇
  2007年   252篇
  2006年   241篇
  2005年   216篇
  2004年   196篇
  2003年   185篇
  2002年   141篇
  2001年   75篇
  2000年   64篇
  1999年   66篇
  1998年   34篇
  1997年   30篇
  1996年   20篇
  1995年   18篇
  1994年   11篇
  1993年   10篇
  1992年   25篇
  1991年   19篇
  1990年   26篇
  1989年   13篇
  1988年   17篇
  1987年   17篇
  1986年   29篇
  1985年   22篇
  1984年   12篇
  1983年   10篇
  1982年   5篇
  1981年   4篇
  1980年   3篇
  1978年   4篇
  1973年   7篇
  1967年   3篇
  1965年   2篇
  1963年   2篇
排序方式: 共有4641条查询结果,搜索用时 15 毫秒
101.
Aortic elasticity and size in bicuspid aortic valve syndrome.   总被引:2,自引:0,他引:2  
AIMS: To investigate the relation between aortic elastic properties and size in bicuspid aortic valves (BAVs). METHODS AND RESULTS: 127 BAV outpatients (121 males; age 23 +/- 10 years) with no or mild valvular impairment, were recruited with 114 control subjects comparable for age, gender, and body size. Aortic distensibility (DIS) and stiffness index (SI) were derived by M-mode evaluation of the aortic root together with blood pressure measured by cuff sphygmomanometer. BAVs vs. controls had increased aortic diameter (P < 0.0001), higher systolic (P = 0.02) and pulse (P = 0.04) pressures. DIS was lower in BAVs than in controls (4.71 +/- 3.67 vs. 7.44 +/- 3.94 10(-6) cm(2)dyne(-1), respectively; P < 0.0001) and SI was greater in BAVs (7.21 +/- 4.93 vs. 3.57 +/- 1.88, respectively; P < 0.0001). Definite impairment in aortic elasticity was present in 53 (42%) BAVs. Both DIS and SI were related (P < 0.0001) to aortic size in BAVs and controls. After adjusting for aortic size and blood pressure, the regression relations between SI and aortic diameter of BAVs were significantly different from controls (P = 0.0052). CONCLUSION: Abnormal aortic elasticity is a common finding in BAVs with no or mild aortic valve impairment. However, impaired aortic stiffness is not due to aortic dilation. Simple assessment of aortic size may thus fail to identify early abnormal load bearing characteristics of the aortic wall in BAVs.  相似文献   
102.
103.
104.
105.
Patients with cardiovascular disease and, namely, heart failure are more susceptible to coronavirus disease 2019 (COVID‐19) and have a more severe clinical course once infected. Heart failure and myocardial damage, shown by increased troponin plasma levels, occur in at least 10% of patients hospitalized for COVID‐19 with higher percentages, 25% to 35% or more, when patients critically ill or with concomitant cardiac disease are considered. Myocardial injury may be elicited by multiple mechanisms, including those occurring with all severe infections, such as fever, tachycardia, adrenergic stimulation, as well as those caused by an exaggerated inflammatory response, endotheliitis and, in some cases, myocarditis that have been shown in patients with COVID‐19. A key role may be that of the renin–angiotensin–aldosterone system. Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infects human cells binding to angiotensin‐converting enzyme 2 (ACE2), an enzyme responsible for the cleavage of angiotensin II into angiotensin 1–7, which has vasodilating and anti‐inflammatory effects. Virus‐mediated down‐regulation of ACE2 may increase angiotensin II stimulation and contribute to the deleterious hyper‐inflammatory reaction of COVID‐19. On the other hand, ACE2 may be up‐regulated in patients with cardiac disease and treated with ACE inhibitors or angiotensin receptor blockers. ACE2 up‐regulation may increase the susceptibility to COVID‐19 but may be also protective vs. angiotensin II‐mediated vasoconstriction and inflammatory activation. Recent data show the lack of untoward effects of ACE inhibitors or angiotensin receptor blockers for COVID‐19 infection and severity. Prospective trials are needed to ascertain whether these drugs may have protective effects.  相似文献   
106.
This study examined the time‐course of reading single words in children and adults using masked repetition priming and the recording of event‐related potentials. The N250 and N400 repetition priming effects were used to characterize form‐ and meaning‐level processing, respectively. Children had larger amplitude N250 effects than adults for both shorter and longer duration primes. Children did not differ from adults on the N400 effect. The difference on the N250 suggests that automaticity for form processing is still maturing in children relative to adults, while the lack of differentiation on the N400 effect suggests that meaning processing is relatively mature by late childhood. The overall similarity in the children's repetition priming effects to adults' effects is in line with theories of reading acquisition, according to which children rapidly transition to an orthographic strategy for fast access to semantic information from print.  相似文献   
107.
We explored the molecular mechanisms involved in the establishement of CMA‐03/06, an IL‐6‐independent variant of the multiple myeloma cell line CMA‐03 previously generated in our Institution. CMA‐03/06 cells grow in the absence of IL‐6 with a doubling time comparable with that of CMA‐03 cells; neither the addition of IL6 (IL‐6) to the culture medium nor co‐culture with multipotent mesenchymal stromal cells increases the proliferation rate, although they maintain the responsiveness to IL‐6 stimulation as demonstrated by STAT1, STAT3, and STAT5 induction. IL‐6 independence of CMA‐03/06 cells is not apparently due to the development of an autocrine IL‐6 loop, nor to the observed moderate constitutive activation of STAT5 and STAT3, since STAT3 silencing does not affect cell viability or proliferation. When compared to the parental cell line, CMA‐03/06 cells showed an activated pattern of the NF‐κB pathway. This finding is supported by gene expression profiling (GEP) analysis identifying an appreciable fraction of modulated genes (28/308) in the CMA‐03/06 subclone reported to be involved in this pathway. Furthermore, although more resistant to apoptotic stimuli compared to the parental cell line, CMA‐03/06 cells display a higher sensibility to NF‐κB inhibition induced by bortezomib. Finally, GEP analysis suggests an involvement of a number of cytokines, which might contribute to IL‐6 independence of CMA‐03/06 by stimulating growth and antiapoptotic processes. In conclusion, the parental cell‐line CMA‐03 and its variant CMA‐03/06 represent a suitable model to further investigate molecular mechanisms involved in the IL‐6‐independent growth of myeloma cells. © 2013 Wiley Periodicals, Inc.  相似文献   
108.
109.
110.
ObjectiveThe objective was to evaluate the seasonal lipid variations in type 2 diabetic (DM2) outpatients.Materials/Methods302 (183 women and 119 men) DM2 subjects with or without statins therapy were screened. Body weight, HbA1c, total cholesterol (TC), high density lipoprotein (HDL-C), triglycerides (Trg) and low density lipoprotein cholesterol (LDL-C) were measured and patients’ data of diet and physical activity were recorded during fall/winter (F/W) and spring/summer (S/S) seasons.ResultsHbA1c levels showed seasonal variability without statistical significance. During the colder seasons we observed an increase (P<.05) of weight associated with higher calorie intake and reduced physical activity. We showed a peak of TC, LDL-C and Trg levels during F/W while HDL-C levels were reduced. Median TC levels in F/W with respect to S/S were 197 vs 185 mg/dL (P<.001) without statins therapy and 172 vs 161 mg/dL (P<.001) in patients under statins therapy. Median LDL-C levels, without or with statin therapy, were 122 vs 114 mg/dL (P<.001) and 97.5 vs 88.5 mg/dL (P<.001), respectively. This seasonal lipids changes from F/W to S/S, modulated the percent of patients at LDL-C target < 100 mg/dL, both without or under statins treatment: from 22% to 29.5% (P<.05) with odds ratio 0.73 (95% CI 0.62–0.87) and from 47% to 55% (P<.001) with odds ratio 0.68 (95% CI 0.58–0.76), respectively.ConclusionsDM2 patients showed a peak of TC and LDL-C during colder months associated with changes of diet and lifestyle habits. This seasonal lipid trend modified the percentage of patients at LDL-C therapeutical target.  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