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   3403篇
  免费   211篇
  国内免费   27篇
耳鼻咽喉   29篇
儿科学   130篇
妇产科学   53篇
基础医学   377篇
口腔科学   267篇
临床医学   339篇
内科学   712篇
皮肤病学   28篇
神经病学   185篇
特种医学   94篇
外科学   578篇
综合类   37篇
一般理论   1篇
预防医学   436篇
眼科学   14篇
药学   250篇
中国医学   1篇
肿瘤学   110篇
  2023年   8篇
  2022年   9篇
  2021年   64篇
  2020年   35篇
  2019年   59篇
  2018年   67篇
  2017年   47篇
  2016年   56篇
  2015年   51篇
  2014年   91篇
  2013年   180篇
  2012年   193篇
  2011年   224篇
  2010年   113篇
  2009年   102篇
  2008年   216篇
  2007年   232篇
  2006年   202篇
  2005年   210篇
  2004年   215篇
  2003年   224篇
  2002年   216篇
  2001年   63篇
  2000年   49篇
  1999年   68篇
  1998年   52篇
  1997年   45篇
  1996年   44篇
  1995年   27篇
  1994年   28篇
  1993年   28篇
  1992年   32篇
  1991年   37篇
  1990年   30篇
  1989年   24篇
  1988年   22篇
  1987年   21篇
  1986年   13篇
  1985年   23篇
  1984年   18篇
  1983年   17篇
  1982年   22篇
  1981年   23篇
  1980年   16篇
  1979年   14篇
  1978年   15篇
  1977年   7篇
  1976年   10篇
  1975年   12篇
  1966年   7篇
排序方式: 共有3641条查询结果,搜索用时 15 毫秒
81.
OBJECTIVE: High IgA-class (but not IgG-class) Anti-Heat-shock-protein 60 antibody level is a predictor of coronary risk in dyslipidemic middle-aged men. In this paper we studied the joint effects of high Anti-Hsp60-antibody level and the classical coronary risk factors. METHODS: We used nested case-control design and logistic regression analyses. The cases consisted of 233 middle-aged men with myocardial infarction or coronary death during 8.5-year follow-up in Helsinki Heart Study, a coronary primary prevention study with gemfibrozil. The controls were subjects without coronary events, matched for drug treatment and the geographical area. RESULTS: The relative coronary risks (Odds Ratios (ORs); 95% confidence interval) were 1.41 (0.96-2.05) for high IgA-class Anti-Hsp60 antibody level and 1.98 (1.35-2.90) for hypertension, defined as mean arterial pressure >114 mmHg. With simultaneous occurrence of high Anti-Hsp60 antibody level and hypertension, the ORs were 2.32 (1.26-4.27) for systolic and 2.99 (1.63-5.48) for diastolic hypertension. Similar patterns of joint effects were found between high Anti-Hsp60 antibody and lipoprotein cholesterol levels as well as antibodies against oxidized low-density lipoprotein. CONCLUSIONS: Our results suggest that, while high IgA-class Anti-Hsp60 antibody level predicts coronary risk, the effect is modest without simultaneous occurrence of other classical risk factors.  相似文献   
82.
83.
Both insulin resistance and inflammation may contribute to the onset of preeclampsia. They also could be interrelated. We studied the relationship between inflammatory cytokines and markers of insulin resistance. During their third trimester, 22 proteinuric preeclamptic women and 16 normotensive controls underwent intravenous glucose tolerance test (minimal model). Preeclamptic women were more insulin-resistant (P = .009), and they had higher levels of serum soluble tumor necrosis alpha receptor II (TNFalpha RII) (P = .002), triglycerides (P = .006), uric acid (P = .001), and leptin (P = .002) than did the controls. However, the study groups did not differ in serum TNFalpha, C-reactive protein (CRP), interleukin-6 (IL-6), sex hormone-binding globulin (SHBG), and high-density lipoprotein-2 (HDL(2))-cholesterol. In multiple regression analysis only SHBG (P = .01) and triglycerides (P = .0036) were associated with insulin sensitivity independently of body mass index (BMI), weight gain, HDL(2)-cholesterol, CRP, TNFalpha, and TNFalpha RII, IL-6, and leptin. We conclude that insulin resistance and the inflammatory markers studied were not associated in established preeclampsia.  相似文献   
84.
Background: Previous studies suggest only minor changes in bile acid metabolism after panproctocolectomy with ileal pouch construction.Aims/Methods: To investigate these changes further, we studied cholesterol absorption and serum, biliary and fecal non-cholesterol sterols and lipids in 12 ileal pouch patients and 10 controls.Results: In patients, cholesterol absorption was markedly reduced and was associated with low serum total and LDL cholesterol and LDL triglyceride levels, but surprisingly, cholesterol synthesis, as indicated by sterol-balance data or serum cholesterol precursor levels, was within low normal limits. The high proportions of serum plant sterol to cholesterol, particularly that of campesterol, were not related to cholesterol absorption, but were attributable to a markedly reduced biliary cholesterol secretion. Interestingly, in these patients the fractional absorption of campesterol was normal, whereas that of sitosterol, like cholesterol, was reduced and was positively related to the intestinal influx of cholesterol. The patients' serum cholestanol proportion was normal, but the proportion of the cholestanol formed during intestinal passage was significantly reduced (17.9% vs 65.2% in controls).Conclusions: Thus ileal pouch patients are characterized by sterol malabsorption, lowered serum total and LDL-cholesterol levels, but unexpectedly without any increase in cholesterol synthesis. The lack of high serum cholestanol, shown earlier frequently in unoperated patients with ulcerative colitis, may indicate reversible cholestasis, a finding deserving further exploration.  相似文献   
85.
OBJECTIVEThe use of remote real-time continuous glucose monitoring (CGM) in the hospital has rapidly emerged to preserve personal protective equipment and reduce potential exposures during coronavirus disease 2019 (COVID-19).RESEARCH DESIGN AND METHODSWe linked a hybrid CGM and point-of-care (POC) glucose testing protocol to a computerized decision support system for continuous insulin infusion and integrated a validation system for sensor glucose values into the electronic health record. We report our proof-of-concept experience in a COVID-19 intensive care unit.RESULTSAll nine patients required mechanical ventilation and corticosteroids. During the protocol, 75.7% of sensor values were within 20% of the reference POC glucose with an associated average reduction in POC of 63%. Mean time in range (70–180 mg/dL) was 71.4 ± 13.9%. Sensor accuracy was impacted by mechanical interferences in four patients.CONCLUSIONSA hybrid protocol integrating real-time CGM and POC is helpful for managing critically ill patients with COVID-19 requiring insulin infusion.  相似文献   
86.
87.
Sleep apnea–hypopnea syndrome (SAHS) causes impairment of daytime functions and increases risk of cardiovascular diseases. Apnea–hypopnea index (AHI), currently used for the estimation of the severity of SAHS, does not contain information on the morphology or duration aspects of the breathing cessations and related oxygen desaturations. Longer breathing cessations and deeper desaturations may have more severe consequences than shorter and shallower ones. To address these issues, novel parameters containing information on the duration and morphology of breathing cessations and oxygen desaturations were calculated and evaluated on 160 male patients (40 patients in normal, mild, moderate and severe AHI severity categories). Obstruction and desaturation duration parameters consist of sum of event durations normalized with the total analysed time. Desaturation severity is a sum of desaturation event areas normalized with total analysed time and obstruction severity parameter is a sum of the products of apnea and hypopnea durations and related desaturation areas normalized with total analysed time. The median follow-up time of the patients was 183 months (range 154–215 months). The 40 patients in each category were further divided into subgroups A and B with lowest and highest novel parameter values, respectively. AHI showed no differences between the subgroups. Mortality was increased in subgroups B compared to subgroups A. The correlation of the novel parameters with AHI was only moderate and the parameter values were partially overlapping between the AHI severity categories. This suggests that patients with similar AHI may in fact suffer from SAHS of very different severity. Thus, the present results suggest that the novel parameters could bring new insight to the individual estimation of the severity of SAHS.  相似文献   
88.
89.
In this study, a dimethacrylate monomer, 1,4-Bis[2-(4-(2′-hydroxy-3′-methacryloyloxy-propoxy)phenyl)-2propyl]benzene (BMPPB) was synthesized to replace 2,2-bis[4-(2′-hydroxyl-3′-methacryloyloxy-propoxy)phenyl]propane (Bis-GMA) as one component of dental restorative materials. The structure of BMPPB and its intermediate product 1,4-bis[2-(4-(oxiranylmethoxy)phenyl)-2propyl]benzene (BOPPB) were confirmed by Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance spectroscopy (1H-NMR), and elemental analysis. In order to evaluate the possibility of replacing Bis-GMA with BMPPB in dental resin, double bond conversion (DC), polymerization shrinkage, contact angle, water sorption (WS) and solubility (SL), and flexural strength (FS) and modulus of BMPPB/tri(ethylene glycol)dimethacrylate (TEGDMA) (50/50?wt) resin system and Bis-GMA/BMPPB/TEGDMA (25/25/50?wt) resin system were studied. Commercially used Bis-GMA/TEGDMA (50/50?wt) dental resin system was used as reference. The results showed that BMPPB-contained copolymer had higher DC, higher WS and SL than the copolymer that only contained Bis-GMA (p?<?0.05). All of the copolymers had nearly the same contact angle (p?>?0.05). BMPPB/TEGDMA resin system had lower polymerization shrinkage, higher FS and modulus (p?<?0.05) than Bis-GMA/TEGDMA resin system. There was no significant difference on polymerization shrinkage, FS and modulus (p?>?0.05) between Bis-GMA/BMPPB/TEGDMA resin system and Bis-GMA/TEGDMA resin system. Before and after water immersion, both FS and modulus of every copolymer did not change significantly (p?>?0.05). Therefore, BMPPB had potential to be used to replace Bis-GMA as base resin in dental restorative materials, but many studies should be undertaken further.  相似文献   
90.
Primary open angle glaucoma (POAG) is a genetically and phenotypically complex disease that is a leading cause of blindness worldwide. Previously we completed a genome‐wide scan for early‐onset POAG that identified a locus on 9q22 (GLC1J). To identify potential causative variants underlying GLC1J, we used targeted DNA capture followed by high throughput sequencing of individuals from four GLC1J pedigrees, followed by Sanger sequencing to screen candidate variants in additional pedigrees. A mutation likely to cause early‐onset glaucoma was not identified, however COL15A1 variants were found in the youngest affected members of 7 of 15 pedigrees with variable disease onset. In addition, the most common COL15A1 variant, R163H, influenced the age of onset in adult POAG cases. RNA in situ hybridization of mouse eyes shows that Col15a1 is expressed in the multiple ocular structures including ciliary body, astrocytes of the optic nerve and cells in the ganglion cell layer. Sanger sequencing of COL18A1, a related multiplexin collagen, identified a rare variant, A1381T, in members of three additional pedigrees with early‐onset disease. These results suggest genetic variation in COL15A1 and COL18A1 can modify the age of onset of both early and late onset POAG.  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