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   10584篇
  免费   958篇
  国内免费   15篇
耳鼻咽喉   79篇
儿科学   249篇
妇产科学   285篇
基础医学   1537篇
口腔科学   268篇
临床医学   1215篇
内科学   2437篇
皮肤病学   76篇
神经病学   815篇
特种医学   434篇
外科学   1270篇
综合类   181篇
一般理论   6篇
预防医学   1295篇
眼科学   108篇
药学   744篇
中国医学   4篇
肿瘤学   554篇
  2021年   142篇
  2020年   91篇
  2019年   142篇
  2018年   160篇
  2017年   101篇
  2016年   150篇
  2015年   149篇
  2014年   259篇
  2013年   329篇
  2012年   453篇
  2011年   525篇
  2010年   295篇
  2009年   243篇
  2008年   505篇
  2007年   459篇
  2006年   458篇
  2005年   434篇
  2004年   372篇
  2003年   356篇
  2002年   342篇
  2001年   322篇
  2000年   322篇
  1999年   297篇
  1998年   130篇
  1997年   106篇
  1996年   124篇
  1995年   98篇
  1993年   79篇
  1992年   271篇
  1991年   250篇
  1990年   246篇
  1989年   231篇
  1988年   228篇
  1987年   193篇
  1986年   223篇
  1985年   194篇
  1984年   187篇
  1983年   177篇
  1982年   121篇
  1981年   105篇
  1980年   84篇
  1979年   158篇
  1978年   121篇
  1977年   107篇
  1976年   90篇
  1975年   80篇
  1974年   110篇
  1973年   105篇
  1972年   87篇
  1968年   88篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Erectile impotence is a common and distressing problem in diabetic men. In order to examine the impact of a penile prosthesis on the quality of life of the recipients, we mailed a questionnaire to all patients (N = 49) who received a semi-rigid (Small-Carrion) prosthesis at the Seattle VAMC from 1976 to 1981. Fourteen patients with diabetes and 23 without diabetes returned the questionnaire. Direct comparisons showed no statistically significant differences between the responses of the two groups. Based on a scale of 1-7 (1 = worst, 4 = no change, 7 = best), the general effect of the operation on the quality of life of the recipients was 5.7 +/- 0.3 (Mean +/- SEM); the quality of intercourse was 5.1 +/- 0.3; the patient's perception of his partner's response to the prosthesis was 5.2 +/- 0.3; and the patient's perception of postoperative changes in his relationship with his partner was 5.6 +/- 0.3. Eighty-three percent of the patients were satisfied with the performance of the prosthesis. Most of the patients (86%) felt that their preoperative expectations had been fulfilled and would elect to have the procedure if they had it to do over again. However, five patients (14%) stated that they would not elect the operation again because their partners did not appreciate the operation (N = 2); the operation produced severe, prolonged pain (N = 1); or the patient's expectations had not been fulfilled (N = 2). Preoperative counseling should be used to foster realistic patient and partner expectations. This operation, which appears to improve the quality of life for most diabetic patients with erectile impotence, should be considered a part of standard care and not as a cosmetic procedure or extraordinary care.  相似文献   
942.
Hyperthyroidism caused by nodular goiters is a common disease of aging cats. Growth and iodine metabolism were studied by autoradiography in normal and hyperfunctioning thyroid tissue obtained from cats injected with 125I before surgery, and in xenografts, grown in nude mice, after double-labeling with 131I and [3H]thymidine. Hyperthyroid cat goiters contain single or multiple hyperplastic nodules, consisting of highly cellular tissue with an iodine metabolism exceeding that of the surrounding normal tissue. Xenografts of hyperplastic hot tissue in thyroxine-treated nude mice retain their original histologic pattern and continue to accumulate radioiodine intensely. Autoradiographs assessed for [3H]thymidine incorporation reveal autonomously proliferating follicular cells within the hyperplastic foci but not within the normal tissue. Administration of sera from donor cats into host mice fails to stimulate the xenografts. Neither hyperfunction nor growth of toxic cat goiters depends on extrathyroidal stimulators. The basic lesion appears to be an excessive intrinsic growth capacity of some thyroid cells.  相似文献   
943.
Samples from prospectively followed recipients, their respective donors, and a cohort of random donors were used to evaluate the specificity and efficacy of a recombinant immunoblot assay (RIBA) as an adjunct to anti-hepatitis C virus (HCV) testing by enzyme immunoassay (EIA). RIBA reacted (RIBA+) in 100 percent of patients who developed hepatitis associated with anti-HCV seroconversion documented by EIA and in 100 percent of the EIA-positive (EIA+) donors implicated in these cases. In contrast, RIBA reacted in none of 10 recipients who were EIA+ but did not develop hepatitis, in none of 7 EIA+ patients with hepatitis B or cytomegalovirus infection, in 33 percent of EIA+ donors who were not implicated in hepatitis transmission, and in 37 percent of EIA+ random donors. Hence, the vast majority of EIA+ individuals who have ancillary evidence of HCV infection react on RIBA, whereas the majority of EIA+ individuals in low-risk settings do not react (RIBA-negative, or RIBA-). There was a strong association between RIBA reactivity and the presence of a surrogate marker (elevated alanine aminotransferase [ALT] and/or antibody to hepatitis B core antigen); 43 percent of RIBA+ implicated donors had a surrogate marker as compared to none of 14 EIA+, RIBA- donors. Among EIA+ random donors, 77 percent of those with a surrogate marker were RIBA+, as compared with 29 percent of those without a surrogate marker. In addition, in EIA+ donors, RIBA reactivity correlated with the extent of ALT elevation; 86 percent of those with an ALT greater than 135 IU per L were RIBA+ compared with 18 percent of those with an ALT less than 30 IU per L.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
944.
945.
946.
OBJECTIVE. Mycoplasma arthritidis mitogen (MAM) is mitogenic for mouse, rat, and human T cells, and behaves as a superantigen in mice through its capacity to bind to the alpha chain of I-E molecules and engage entire sets of T cells expressing specific V beta. Here, we have attempted to fully characterize the V beta-engaging activities of MAM in mice, and define similar activities in rats and humans. METHODS. Multiprobe RNase-protection assays and mice transgenic for human DR alpha, DR beta, and DR alpha beta were utilized for this purpose. RESULTS. MAM-reactive V beta in the mouse included not only the previously reported V beta 6, V beta 8.1, V beta 8.2, and V beta 8.3, but also V beta 5.1. In the rat, engagement of V beta 5.1, V beta 6, V beta 8.1, and V beta 8.2, but not V beta 8.3, was documented, whereas in humans, the engaged V beta included primarily V beta 19.1 (alternatively termed V beta 17.1) and, to a lesser extent, V beta 3.1, V beta 11.1, V beta 12.1, and V beta 13.1. In DR transgenic E alpha- E beta- mice, presentation of MAM and engagement of specific V beta was effected by DR alpha. CONCLUSIONS. Homologous V beta are engaged by MAM in mice, rats, and humans, presumably through a binding site similar to that proposed previously for other superantigens. MAM presentation primarily via the nonpolymorphic DR alpha makes it unlikely that there is involvement of such a superantigen in the pathogenesis of autoimmune diseases known to be associated with certain DR haplotypes. The possibility cannot be excluded, however, that superantigen-activated T cells may lead to disease by cross-reactions with self-antigens presented by particular DR haplotypes.  相似文献   
947.
Background Current guidelines recommending cardiac rehabilitation (CR) after coronary revascularization are largely based on early studies that evaluated only a subset of the population and failed to assess the impact of CR on a patient's perception of their functional status. The main objective of this study was to evaluate the impact of CR in a diverse contemporary population on patient functional outcomes. Methods We studied the effect of CR on 6-month SF-36 Physical Functioning (PF) in 700 patients (mean age 67 ± 11 years, 37% women) who underwent coronary bypass grafting or percutaneous intervention from August 1998 to July 2000. Results Overall CR participation was 24%. At baseline, CR participants had higher PF (mean 62.5 vs 52.5, P < .001). After adjusting for baseline clinical variables and PF score, CR was associated with significant improvement in 6-month PF (+5.0, 95% CI 1.0-9.0). This improvement was observed in all patient subgroups, but tended to be greater in magnitude in men versus women, patients aged <70 years versus ≥70 years, and patients with coronary bypass grafting versus patients with percutaneous intervention. CR participants also tended to be more likely to engage in regular exercise (63% vs 55%, P = .06) and modify their diet (82% vs 73%, P = .07). Rates of rehospitalization and repeat revascularization were similar among CR participants and nonparticipants. Conclusions CR after coronary revascularization is associated with improved functional outcomes and adoption of secondary preventive measures. Innovative strategies to facilitate CR enrollment and tailoring programs to better address the needs of all patient subgroups would extend these benefits to more eligible patients. (Am Heart J 2003;145:445-51.)  相似文献   
948.
The ultrashort-acting beta blocker flestolol was studied during atrial pacing and atrial fibrillation (AF) in 10 patients with Wolff-Parkinson-White syndrome. Flestolol was given as a 100-micrograms/kg bolus followed by a 10-micrograms/kg/min infusion for 15 minutes. The drug did not alter the antegrade effective refractory period of the accessory pathway or the atrial paced cycle length at which block occurred in the accessory pathway. After flestolol, the percent of preexcited QRS complexes during AF increased (60 +/- 10 vs 87 +/- 5%, p = 0.01). Despite this, the ventricular rate slowed, with increases in mean RR interval (382 +/- 20 vs 416 +/- 22 ms, p = 0.02) and in the shortest interval between preexcited QRS complexes (251 +/- 18 vs 270 +/- 17 ms, p less than 0.01). The effect of isoproterenol 3 to 5 micrograms/min was studied in 5 patients. During atrial pacing, isoproterenol decreased the antegrade refractory period and the atrial paced cycle length of block in the accessory pathway (p less than or equal to 0.05). During AF, it decreased the percent of preexcited QRS complexes, mean RR interval and shortest interval between preexcited QRS complexes (p less than 0.05). Flestolol reversed the effects of isoproterenol both during atrial pacing and AF. Thus, flestolol does not alter conduction over the accessory pathway during atrial pacing, but during AF it slows conduction over the accessory pathway and prevents isoproterenol-mediated increases in ventricular rate. This suggests that in patients with Wolff-Parkinson-White syndrome sympathetic stimulation after the onset of AF enhances conduction over the accessory pathway and is an important determinant of ventricular rate.  相似文献   
949.
Objectives: The Stoma-QOL questionnaire is a patient-reported outcome (PRO) used to measure quality of life in patients with ileostomy or colostomy. This study assesses the Stoma-QOL’s overall and item-level psychometric characteristics in patients with temporary stomas, and whether stoma-related quality of life differs by demographic characteristics.

Materials and methods: Analysis of cross-sectional observational PRO data from hospitals in Vancouver, Canada. Patients registered for elective ileostomy or colostomy closure, over the age of 18, and able to read English were eligible for participation. Emergent and cancer-related cases were excluded. One-way analysis of variance was used to test for demographic differences in Stoma-QOL scores. Cronbach’s alpha was used for reliability, and Rasch item-response theory was used to assess overall and item characteristics.

Results: 120 patients were included. No statistically significant difference in Stoma-QOL scores was found by age, sex, or socioeconomic status. Reliability was 0.93. Mean item responses ranged from 1.77 to 3.55 and item-total correlation ranged from 0.51 to 0.77. The Rasch item-response theory model demonstrated significant misfit, likely due to the misfit of item 9, which asks about sexuality, and high residual correlations between item pairs 6 and 8 about fatigue, and items 16 and 17 about social relationships.

Conclusions: The Stoma-QOL questionnaire is a well-designed PRO for measuring stoma-related quality of life. Demographic variables do not appear to have a strong influence on Stoma-QOL scores. Item 9 demonstrated misfit but removal likely does not improve the instrument. Future research should focus on revising items 6, 8, 16, and 17.  相似文献   

950.
Peterson LF  Peterson LR 《Angiology》2004,55(5):499-506
The benefits of mobile cardiac catheterization laboratories include keeping patients closer to their families, communities, local hospitals, and primary care physicians while receiving services comparable to those available at tertiary centers. However, there are very few studies regarding the safety of performing cardiac catheterization in mobile laboratories at remote locations. Thus, the authors performed an observational study of 1,775 consecutive patients undergoing a diagnostic cardiac catheterization in a mobile catheterization laboratory at primary care hospitals served by the Appleton Heart Institute (AHI) from August 1, 1991, to December 31, 1998. Twenty-three percent (1,775/7,637) of all AHI diagnostic cases in this time period were performed in the mobile catheterization laboratory. Urgent transfer to the tertiary care facility via ambulance or helicopter was used for 2.3% of patients (n = 41). The overall complication rate was 1.2% (n = 21). Of the patients who underwent cardiac catheterization in the mobile laboratory, 32.6% (n = 579) were subsequently referred for interventional or surgical revascularization. There were no deaths. Cardiac catheterizations can be performed safely in a mobile laboratory at primary care hospitals, provided that immediate transfer is available for those in need of urgent intervention or revascularization and that unstable patients are not studied in the mobile laboratory.  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