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   2500篇
  免费   189篇
  国内免费   59篇
耳鼻咽喉   25篇
儿科学   110篇
妇产科学   45篇
基础医学   342篇
口腔科学   273篇
临床医学   261篇
内科学   515篇
皮肤病学   49篇
神经病学   151篇
特种医学   186篇
外科学   181篇
综合类   26篇
预防医学   243篇
眼科学   27篇
药学   182篇
  1篇
中国医学   34篇
肿瘤学   97篇
  2023年   19篇
  2022年   40篇
  2021年   64篇
  2020年   49篇
  2019年   66篇
  2018年   73篇
  2017年   61篇
  2016年   75篇
  2015年   86篇
  2014年   113篇
  2013年   118篇
  2012年   143篇
  2011年   163篇
  2010年   106篇
  2009年   125篇
  2008年   107篇
  2007年   127篇
  2006年   101篇
  2005年   79篇
  2004年   68篇
  2003年   72篇
  2002年   55篇
  2001年   48篇
  2000年   34篇
  1999年   46篇
  1998年   84篇
  1997年   93篇
  1996年   61篇
  1995年   59篇
  1994年   41篇
  1993年   48篇
  1992年   20篇
  1991年   22篇
  1990年   21篇
  1989年   34篇
  1988年   29篇
  1987年   34篇
  1986年   18篇
  1985年   20篇
  1984年   14篇
  1983年   16篇
  1982年   11篇
  1981年   8篇
  1980年   10篇
  1979年   7篇
  1978年   6篇
  1977年   14篇
  1976年   8篇
  1975年   6篇
  1968年   3篇
排序方式: 共有2748条查询结果,搜索用时 11 毫秒
991.
Background:  Detection of oral volatile sulfur compounds (VSC) by gas chromatography (GC) is a widely used method for evaluating breath odor. Air aspirated from the mouth is injected into the GC column for analysis. To eliminate discrepancies caused by variations in operator sampling or injection techniques, a new GC system designed to aspirate breath samples directly into the GC was developed.
Objective:  A clinical study was performed to compare this new automated breath-sampling GC system to organoleptic evaluation by two trained odor judges.
Methods:  A randomized, two-cell, double-blind, parallel design was used in which subjects were tested before and 3 h after using either a mouthrinse containing zinc or a matching placebo rinse. Thirteen subjects used the zinc mouthrinse, and 12 used the placebo. Subjects with a wide range of VSC levels were studied. The average organoleptic ratings for each subject at each time-point were compared with the average VSC measurements made with the GC, and Pearson product–moment correlation coefficients between the corresponding GC and organoleptic measurements were determined.
Results:  The correlation between the GC and organoleptic assessment methods were highly significant ( P  ≤ 0.001) for: total VSC, 0.65; H2S, 0.63; CH3SH, 0.61; and (CH3)2S, 0.46. The correlation between the two judges was also highly significant (0.823, P  < 0.001).
Conclusion:  These results demonstrate the utility of the automated GC method for evaluating breath odor.  相似文献   
992.
993.
994.
Summary— Experiments were performed to determine the subtypes of alpha-adrenoceptors involved in the contraction induced by rilmenidine in isolated canine cutaneous veins. Rings of saphenous vein (without endothelium) were suspended for the recording of isometric force in physiological salt solution. All experiments were performed in the presence of propranolol (to antagonize betaadrenoceptors), cocaine (to inhibit neuronal uptake) and hydrocortisone (to inhibit extraneuronal uptake). In the presence of rauwolscine (an alpha2-adrenergic blocker), rilmenidine caused concentration-dependent contractions which were inhibited by prazosin (nonselective alpha1-antagonist) and by (+)niguldipine (selective alpha1A-adrenergic antagonist), but not by (-)niguldipine. After treatment with phenoxybenzamine (to alkylate alpha1-adrenoceptors), rilmenidine evoked contractions of the canine saphenous vein which were antagonized competitively by rauwolscine. The combination of rauwolscine and prazosin did not abolish contractions evoked by the highest concentrations of rilmenidine. Although binding experiments using 3H-idazoxan suggested the existence of a nonadrenergic binding site (around 20% of the total binding), contractile studies failed to demonstrate their involvement in the increases in tension evoked by rilmenidine. These experiments suggest that the contractions evoked by rilmenidine in isolated canine veins are mediated by both alpha1A- and alpha2-adrenoceptors.  相似文献   
995.
This study set out to identify the educational and research priorities of registered nurses practising in rural and remote areas of Australia. It included two groups of participants, one which identified as rural and another which identified as remote. The findings for the rural cohort in the study are presented in this article. Research participants represented a national sample. The Delphi method was used to obtain the most reliable consensus of the nurse participants. In the final phase of the study, 13 high priorities were identified. Study findings highlight perceived needs for clinical nursing research and continuing education for nurses practising in rural Australia.  相似文献   
996.
The authors propose a treatment to improve skin texture and to decrease thin wrinkles and creases. The treatment is based on the use of 0.1% all-trans retinoic acid intradermic injections (with biopresence of 0.02%) combined with topic cream, immediately followed by 340 Nm blue light skin exposure. These procedures determine the retinoic binding protein stabilization that provides the acid intracellular penetration with its subsequent effects. An average of 10 sessions, once a week was required.  相似文献   
997.
Objectives To understand the factors associated with a post‐menopausal woman deciding to take hormone replacement therapy (HRT) after reviewing a decision aid (DA) and having a counselling visit with her physician as well as the factors associated with the act of taking HRT 2 months after the counselling interview. Design A secondary analysis of data collected for a randomized controlled trial evaluating two DAs. Main outcome results Although 28% of women were uncertain regarding their decision after the counselling interview, only 2.4% of women, at the assessment at 2 months, had not made a decision. The most significant factor associated with the decision to take HRT, after the physician visit, was the physician preference (OR: 62, 95% CI: 13.3, 289.7). Physician preference (OR: 78, 95% CI: 6.2, 975) remained the most significant factor for taking HRT 2 months after the counselling interview followed by low uncertainty about the decision (OR: 0.4, 95% CI: 0.2, 0.7). Conclusion Physician preference was the factor that was most associated with the woman's decision following counselling and 2 months later. Qualitative evaluation of the interview process involving the patient and physician would determine whether the patient and physician are reaching a shared decision or is the physician preference influencing the patient.  相似文献   
998.
The present study investigated the potential of Concanavalin A lectin (Con A) conjugated to liposomes (Con A‐liposomes) for targeting doxorubicin (DOX) to cells. The physicochemical properties and the cytotoxicity of DOX‐loaded Con A‐liposomes were evaluated. DOX‐loaded Con A‐liposomes were prepared by incubation of DOX‐loaded liposomes with a Con A‐SATA derivative. Lectin biological activity was monitored before and after conjugation by a hemagglutinating assay. The cytotoxicity of DOX‐loaded Con A‐liposomes was evaluated in terms of the inhibition of NCI‐H299 and HEp‐2 cell proliferation using the MTT method. The affinity of lectinized liposomes with these cells was thus assessed by evaluating the cytotoxic effect of the DOX released into cells. Stable DOX‐loaded Con A‐liposomes were obtained and their high affinity for cells was corroborated. The encapsulation of DOX into Con A‐liposomes produced an inhibition of roughly 70% of Hep‐2 cell proliferation and 50% of cell inhibition was verified on HCI‐H292. DOX in solution was able to inhibit only 20% of cell proliferation for both cell lines. Unloaded Con A‐liposomes were not cytotoxic. The encapsulation of DOX into Con A‐liposomes improves drug penetration into cells, thereby enhancing its cytotoxicity, especially in Hep‐2 cells. Drug Dev. Res. 67:430–437, 2006. © 2006 Wiley‐Liss, Inc.  相似文献   
999.
1000.
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