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   11029篇
  免费   535篇
  国内免费   353篇
耳鼻咽喉   20篇
儿科学   293篇
妇产科学   148篇
基础医学   1302篇
口腔科学   110篇
临床医学   756篇
内科学   3094篇
皮肤病学   76篇
神经病学   484篇
特种医学   298篇
外科学   881篇
综合类   1226篇
预防医学   1027篇
眼科学   23篇
药学   1567篇
  4篇
中国医学   328篇
肿瘤学   280篇
  2023年   187篇
  2022年   464篇
  2021年   541篇
  2020年   395篇
  2019年   408篇
  2018年   409篇
  2017年   262篇
  2016年   322篇
  2015年   345篇
  2014年   713篇
  2013年   717篇
  2012年   599篇
  2011年   754篇
  2010年   551篇
  2009年   540篇
  2008年   593篇
  2007年   535篇
  2006年   406篇
  2005年   286篇
  2004年   215篇
  2003年   171篇
  2002年   166篇
  2001年   113篇
  2000年   105篇
  1999年   92篇
  1998年   103篇
  1997年   111篇
  1996年   120篇
  1995年   103篇
  1994年   113篇
  1993年   109篇
  1992年   103篇
  1991年   102篇
  1990年   79篇
  1989年   104篇
  1988年   86篇
  1987年   86篇
  1986年   62篇
  1985年   95篇
  1984年   92篇
  1983年   45篇
  1982年   88篇
  1981年   63篇
  1980年   64篇
  1979年   59篇
  1978年   40篇
  1977年   45篇
  1976年   39篇
  1975年   29篇
  1974年   25篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
BackgroundNew antidiabetic agents (sodium-glucose cotransporter-2 inhibitor [SGLT2i] and glucagon-like peptide-1 receptor agonist [GLP-1RA]) and metabolic surgery have protective effects on metabolic syndromes.ObjectivesTo compare the changes of metabolic parameters and costs among patients with obesity and type 2 diabetes undergoing metabolic surgery and initiating new antidiabetic agents over 12 months.SettingHong Kong Hospital Authority database from 2006–2017.MethodsThis is a population-wide retrospective cohort study consisting of 2616 patients (1810 SGLT2i, 528 GLP-1RA, 278 metabolic surgery). Inverse probability treatment weighting of propensity score was applied to balance baseline covariates of patients with obesity and type 2 diabetes who underwent metabolic surgery, or initiated SGLT2i or GLP-1RA. Metabolic parameters and direct medical costs were measured and compared from baseline to 12 months in metabolic surgery, SGLT2i, and GLP-1RA groups.ResultsPatients in all 3 groups had improved metabolic parameters over a 12-month period. Patients with metabolic surgery achieved significantly better outcomes in BMI (?5.39, ?.56, ?.40 kg/m2, P < .001), % total weight loss (15.16%, 1.34%, 1.63%, P < .001), systolic (?2.21, ?.59, 1.28 mm Hg, P < .001) and diastolic (?1.16, .50, ?.13 mm Hg, P < .001) blood pressure, HbA1c (?1.80%, ?.77%, ?.80%, P < .001), triglycerides (?.64, ?.11, ?.09 mmol/L, P < .001), and estimated glomerular filtration rate (3.08, ?1.37, ?.41 mL/min/1.73m2, P < .001) after 12 months compared with patients with SGLT2i and GLP1-RA. Although the metabolic surgery group incurred the greatest direct medical costs (US$33,551, US$10,945, US$10,627, P < .001), largely due to the surgery itself and related hospitalization, the total monthly direct medical expenditure of metabolic surgery group became lower than that of SGLT2i and GLP-1RA groups at 7 months.ConclusionBeneficial weight loss and metabolic outcomes at 12 months were observed in all 3 groups, among which the metabolic surgery group showed the most remarkable effects but incurred the greatest medical costs. However, studies with a longer follow-up period are warranted to show long-term outcomes.  相似文献   
12.
Objective: To examine (i) the associations between physical activity dimensions, cardiorespiratory fitness and body composition and, (ii) the associations between physical activity dimensions, cardiorespiratory fitness, body composition and biomarkers of cardiometabolic health in persons with spinal cord injury (SCI).

Methods: A cross-sectional prospective cohort study with 7-day follow-up was conducted. Body composition, cardiorespiratory fitness and biomarkers of cardiometabolic health were measured in thirty-three participants with SCI (> 1 year post injury). Physical activity dimensions were objectively assessed over 7-days.

Results: Activity energy expenditure (r =.43), physical activity level (r =.39), and moderate-to-vigorous physical activity (MVPA) (r =.48) were significantly (P < 0.001) associated with absolute (L/min) peak oxygen uptake (?O2 peak). ?O2 peak was significantly higher in persons performing ≥150 MVPA minutes/week compared to <40 minutes/week (P?=?0.003). Individual physical activity dimensions were not significantly associated with biomarkers of cardiometabolic health. However, body composition characteristics (BMI, waist and hip circumference) showed significant (P < 0.04), moderate (r >.30) associations with parameters of metabolic regulation, lipid profiles and inflammatory biomarkers. Relative ?O2 peak (ml/kg/min) was moderately associated with only insulin sensitivity (r?=?0.37, P?=?0.03).

Conclusions: Physical activity dimensions are associated with cardiorespiratory fitness; however, stronger and more consistent associations suggest that poor cardiometabolic health is associated with higher body fat content. Given these findings, the regulation of energy balance should be an important consideration for researchers and clinicians looking to improve cardiometabolic health in persons with SCI.  相似文献   

13.
14.
Two nonlinear pharmacokinetic models were simulated to investigate the relationship between single and multiple dose bioequivalency parameters for drugs such as phenytoin and propranolol which exhibit either saturable elimination kinetics or a capacity limited first pass effect. Mean Tmax, Cmax and area under the plasma-concentration time curve values from 0 to infinity (AUC 0-infinity) were compared after a single and multiple dose(s) of a test or reference drug. The aim was to determine if there were systematic changes in the limits of the single dose confidence interval at steady state that would limit the usefulness of confidence intervals following a single dose in accurately predicting bioavailability following multiple dosing. The 90 per cent confidence interval expressed as a percentage of the reference mean for Tmax, Cmax, and AUC 0-infinity showed model dependent changes from single to multiple dosing in response to the level of data error and changes in absorption. Changes in clearance also seemed to have a marked effect on the observed limits of the single and multiple dose confidence intervals especially for Cmax which showed a characteristic change in the intervals as a function of the clearance ratio. The model used to describe phenytoin had confidence intervals for Cmax and AUC 0-infinity from single to multiple dosing that were similar to that seen for the experimental data. However, the model predictions for Tmax confidence intervals following single and multiple dosing was at variance with the experimental data for formulations A and B.  相似文献   
15.
16.
根据3.7 L瑞士Bioengineer KLF2000型发酵罐分批发酵的实验数据,利用GraphPad Prism软件对假单胞菌BS-03产鼠李糖脂生物表面活性剂的发酵动力学模型进行非线性拟合,说明Logistic模型和L-P模型能较好的描述假单胞菌BS-03发酵过程中的菌体生长、鼠李糖脂合成和限制性基质的消耗动力学。  相似文献   
17.
目的 探讨血管紧张素Ⅱ(AngⅡ)1型受体拮抗剂(ARB)洛沙坦对代谢综合征(MS)肾组织环氧化酶2(COX-2)表达的影响及其机制。 方法 把7周大的MS模型肥胖Zucker大鼠随机分成洛沙坦处理组和未处理组,以瘦Zucker大鼠为对照组,连续给药4个月后观察肾组织内COX-2的表达。另外,用AngⅡ刺激6 h的系膜细胞和用从微型渗透泵灌注AngⅡ 5 d的C57BL/6小鼠肾脏提取的肾皮质,观察COX-2的表达。采用RT-PCR和Western印迹法分别检测COX-2 mRNA和蛋白的表达。 结果 洛沙坦可阻止肥胖Zucker大鼠肾组织内COX-2表达增加。AngⅡ直接刺激可以诱导系膜细胞和肾组织内COX-2表达增加。 结论 AngⅡ可以调控MS肾组织内COX-2表达增加。ARB可以通过抑制COX-2的表达保护MS肾脏,这对应用非COX-2抑制剂来保护MS肾脏具有重要的意义。  相似文献   
18.
In an in vitro study, 10 gallbladders of adult pigs and 6 gallbladders of lambs, all removed immediately after slaughtering, were stimulated in a water bath by electric means to induce active contraction. Gallbladder emptying was followed by ultrasonography employing five measurement procedures: (1) gallbladder width, (2) longitudinal planimetry, (3) transverse planimetry, (4) ellipsoid method, and (5) sum of cylinders method. In an in vivo investigation, gallbladder emptying of 30 volunteers (12 healthy subjects, 18 diabetics) was evaluated in the same way after ingestion of a fatty meal. Gallbladder width was found to be unsuitable to estimate the decrease in gallbladder volume due to a nonlinear relation of the parameters. Longitudinal planimetry tended to be less valid than transverse planimetry in assessing gallbladder volume reduction. The most valid estimation of gallbladder volume decreases was obtained by the two three-dimensional procedures. However, in neither in vitro nor in vivo could a significant difference between the sum of cylinders method and the ellipsoid method in determining relative volume reduction be established. We conclude that a three-dimensional measurement procedure should be used for valid assessments of gallbladder motility. However, according to our data there is no advantage in using the time-consuming sum of cylinders method compared to the simple ellipsoid method.  相似文献   
19.
牟英 《药学教育》2010,26(2):54-55
通过具体的实验数据,讨论在药代动力学实验中如何加入曲线下面积(AUC)的计算,以帮助学生理解并掌握这一概念;在实验室设置不同剂量组,给药后比较剂量与浓度是否呈等比例关系,以此加深学生对于一级动力学消除及其临床意义的理解。  相似文献   
20.
目的 观察脂肪抽吸对中心型肥胖患者代谢指标的影响。方法 筛选中心型肥胖患者30例,采用肿胀麻醉法,脂肪抽吸量在2000~2500ml;分别检测脂肪抽吸前2d和脂肪抽吸后1周、1个月、2个月、3个月的血脂、血清胰岛素、瘦素、脂联素、抵抗素,并换算出胰岛素抵抗指数(HO-MA-IR)、胰岛素敏感指数(ISI)和血糖及胰岛素下面积。结果脂肪抽吸后1个月、2个月血糖下面积及HOMA-IR均有不同程度的降低,ISI则有所升高(术后1周:P〈0.05;术后1月:P〈0.01);脂肪抽吸后血清瘦素较脂肪抽吸前显著降低(P〈0.01),抵抗素和脂联素较脂肪抽吸前亦有所变化,特别是在术后1个月时变化较为明显(P〈0.05),除血清瘦素、血糖下面积外,其余指标脂肪抽吸后3个月基本恢复原有水平。结论 脂肪抽吸对代谢指标在3个月内有一定的影响,特别是对糖代谢改善显著,但3个月后这种变化基本恢复到原有水平。  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