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   6023篇
  免费   447篇
  国内免费   3篇
耳鼻咽喉   59篇
儿科学   126篇
妇产科学   110篇
基础医学   773篇
口腔科学   81篇
临床医学   608篇
内科学   1136篇
皮肤病学   61篇
神经病学   548篇
特种医学   220篇
外科学   833篇
综合类   88篇
一般理论   5篇
预防医学   905篇
眼科学   84篇
药学   449篇
  1篇
中国医学   3篇
肿瘤学   383篇
  2022年   50篇
  2021年   73篇
  2020年   59篇
  2019年   96篇
  2018年   124篇
  2017年   89篇
  2016年   102篇
  2015年   117篇
  2014年   183篇
  2013年   215篇
  2012年   274篇
  2011年   287篇
  2010年   215篇
  2009年   137篇
  2008年   277篇
  2007年   297篇
  2006年   263篇
  2005年   312篇
  2004年   283篇
  2003年   278篇
  2002年   254篇
  2001年   120篇
  2000年   115篇
  1999年   134篇
  1998年   67篇
  1997年   52篇
  1996年   72篇
  1995年   64篇
  1994年   48篇
  1993年   42篇
  1992年   89篇
  1991年   103篇
  1990年   99篇
  1989年   94篇
  1988年   74篇
  1987年   86篇
  1986年   83篇
  1985年   73篇
  1984年   58篇
  1983年   67篇
  1982年   35篇
  1981年   39篇
  1979年   70篇
  1978年   41篇
  1977年   39篇
  1976年   43篇
  1975年   37篇
  1973年   42篇
  1971年   36篇
  1968年   36篇
排序方式: 共有6473条查询结果,搜索用时 15 毫秒
91.
Aim: We performed a semiprospective and retrospective review of all admissions to a single institution of systemic lupus erythematosus (SLE) patients, admitted due to active disease. The aim was to describe differences in disease activity as a cause of hospital admissions between patients originating from South‐East Asia/China (SAC) and Caucasians. Method: There were 210 patients admitted for active disease, with a total of 567 admissions for active SLE over a 16‐year period. Allowing for patients who had left our database, there was a total of 3415 patient years of observation. Results: Patients from SAC with a flare requiring admission presented earlier in their disease course and with more active disease than did Caucasians (median SLE Disease Activity Index 13 vs. 8, P= 0.002). They had longer inpatient stays (7 vs. 5 days P = 0.03). There was a trend to higher rates of re‐presentation to hospital for flare (59% in SAC patients vs. 41% in Caucasians, P = 0.09) with more subsequent admissions (3 vs. 2 P = 0.06) despite a shorter period of observation. Conclusions: South‐East Asian/Chinese were more likely to be diagnosed with class III/IV glomerulonephritis and require cyclophosphamide both at presentation and subsequent admissions. More patients from SAC were readmitted to hospital for severe central nervous system disease after their first hospital admission. In this population, lupus patients had more severe flares and more frequently required admission for these than Caucasians.  相似文献   
92.
Regular multilaboratory surveys of laboratories derived primarily from Australia, New Zealand, and Southeast Asia have been conducted during the last 8 years to evaluate testing proficiency in the diagnosis of von Willebrand disease (vWD). We summarize and update the findings of these surveys with a particular emphasis on diagnostic errors and error rates associated with particular tests or test panel limitations. A total of 43 plasma samples have been dispatched to survey participants. These have included 13 normal samples, five type 1 vWD samples, eight type 2 vWD samples (three 2A, three 2B, one 2M, and one 2N), and four type 3 vWD samples. In addition to numerical test results, participant laboratories (currently, n = 49) were asked to provide diagnostic interpretations regarding results, and whether or not vWD was suggested, and if so, a probable subtype. Although laboratories usually provided correct interpretative responses, diagnostic errors occurred in a substantial number of cases. On average, type 1 vWD plasma was misidentified as type 2 vWD in 13.3% of cases, and laboratories performing von Willebrand factor (vWF):ristocetin cofactor activity (RCo) without vWF:collagen-binding activity (CB) were seven times more likely to make such an error compared with those performing vWF:CB. Similarly, type 2 vWD plasma was misidentified as type 1 or type 3 vWD in an average of 20.1% of cases, and laboratories performing vWF:RCo without vWF:CB were three times more likely to make such an error compared with those performing vWF:CB. Finally, normal plasma was misidentified as vWD in an average of 6.7% of cases, and laboratories performing vWF:RCo without vWF:CB were four times more likely to make such an error compared with those performing vWF:CB. We conclude that although laboratories are generally proficient in tests for vWD, diagnostic errors do occur and error rates are substantially reduced when test panels are more comprehensive and include the vWF:CB.  相似文献   
93.

Objective

To examine associations between antidepressant use and health care utilization in young adults beginning maintenance hemodialysis (HD) therapy.

Patients and Methods

Antidepressant use, hospitalizations, and emergency department (ED) visits were examined in young adults (N=130; age, 18-44 years) initiating HD (from January 1, 2001, through December 31, 2013) at a midwestern US institution. Primary outcomes included hospitalizations and ED visits during the first year.

Results

Depression diagnosis was common (47; 36.2%) at HD initiation, yet only 28 patients (21.5%) in the cohort were receiving antidepressant therapy. The antidepressant use group was more likely to have diabetes mellitus (18 [64.3%] vs 33 [32.4%]), coronary artery disease (8 [28.6%] vs 12 [11.8%]), and heart failure (9 [32.1%] vs 15 [14.7%]) (P<.05 for all) than the untreated group. Overall, 68 (52.3%) had 1 or more hospitalizations and 33 (25.4%) had 1 or more ED visits in the first year. The risk of hospitalization during the first year was higher in the antidepressant use group (hazard ratio, 2.35; 95% CI, 1.39-3.96; P=.001), which persisted after adjustment for diabetes, coronary artery disease, and heart failure (hazard ratio, 1.94; 95% CI, 1.22-3.10; P=.006). Emergency department visit rates were similar between the groups.

Conclusion

Depression and antidepressant use for mood indication are common in young adult incident patients initiating HD and and are associated with higher hospitalization rates during the first year. Further research should determine whether antidepressants are a marker for other comorbidities or whether treated depression affects the increased health care use in these individuals.  相似文献   
94.
95.
96.
An unusual case of aortic annular abscess is presented, in which the patient presented with features of gross tricuspid regurgitation. There was no direct involvement of the tricuspid valve. Tricuspid regurgitation disappeared following surgical repair of the annular abscess. The present case also illustrates the utility of trans-oesophageal echocardiography in establishing the diagnosis and planning surgical intervention.  相似文献   
97.
Asmus MJ  Vaughan LM  Hill MR  Chesrown SE  Hendeles L 《Chest》2002,121(5):1634-1637
OBJECTIVE: Methacholine solutions < 0.25 mg/mL must be prepared fresh daily, while concentrations > or = 0.25 mg/mL must be prepared at 2-week intervals according to US Food and Drug Administration-required labeling. The purpose of this report was to determine whether freezing methacholine solutions in unit-dose syringes would allow less frequent preparation. DESIGN: Diluent containing 0.5% sodium chloride, 0.275% sodium bicarbonate, and 0.4% phenol was used to prepare 11 concentrations of methacholine ranging from 0.031 to 32.0 mg/mL. Three milliliters of each dilution was placed into 5-mL polypropylene syringes and immediately frozen. Methacholine concentrations were determined using a validated high-performance liquid chromatography assay after preparation (time zero) and at 0.5, 1, 1.5, 2, 3, 4, 5, and 6 months. On the day of analysis, the samples were allowed to thaw to room temperature. An additional set of each dilution was stored at room temperature for 24 h after thawing and then analyzed for methacholine. RESULTS: Samples > or = 0.062 mg/mL analyzed immediately after thawing retained > or = 90% of labeled potency for at least 6 months, while the 0.031-mg/mL sample retained 90% potency for 4 months. Most samples analyzed 24 h after thawing lost potency. CONCLUSION: If prepared and stored in unit-dose syringes frozen, methacholine solutions containing 0.062 to 32.0 mg/mL can be prepared at 6-month intervals, and solutions containing 0.031 mg/mL can be prepared at 4-month intervals. Once thawed, unused methacholine solutions should be discarded.  相似文献   
98.
99.
Blood pressure and physical fitness in children   总被引:3,自引:0,他引:3  
The association between physical fitness and blood pressure was studied in 2061 children selected from all fourth graders in 44 elementary schools in the New York City area. Their blood pressure and physical fitness were measured on two consecutive examinations 1 year apart. Systolic and diastolic blood pressure were highest in children with poor physical fitness. The change in physical fitness between the 2 examination years was related to the change in systolic and diastolic blood pressure (i.e., children with a decline in physical fitness showed the largest rise in blood pressure). These observations suggest that the level of systolic and diastolic blood pressure in children is associated with the level of physical fitness. They also indicate that change in blood pressure in childhood may be related to change in physical fitness.  相似文献   
100.
The pharmacokinetics of human recombinant plasminogen activator inhibitor-1 (rPAI-1) was studied in rabbits. Latent rPAI-1 (0-2 units of tissue-type plasminogen activator neutralizing activity per microgram protein); reactivated rPAI-1 (approximately 150 units/micrograms); and chloramine T-oxidized, nonreactivatable rPAI-1 (approximately 0.7 units/microgram) were studied. The pharmacokinetic parameters for the disposition of rPAI-1 antigen after an intravenous bolus injection of 1.0 or 2.5 mg/kg rPAI-1 were very similar for all three forms: the initial volume of distribution was approximately 60 ml/kg, the initial half-life in plasma was 6 minutes, and the plasma clearance was approximately 4 ml/kg/min. The disposition of PAI activity after injection of reactivated rPAI-1 was similar to that of rPAI-1 antigen. Injection of latent rPAI-1 was associated with a nearly threefold increase in the specific activity of circulating PAI-1 from 2 units/micrograms to 5.0 +/- 1.1 units/micrograms (p less than 0.01) within 1 minute, followed by a cumulative 25-fold increase in specific activity over 1 hour (p = 0.01). In contrast, the specific activity of oxidized or reactivated preparations of rPAI-1 did not increase in the first several minutes after injection. These findings support the existence of a fast-acting but low-capacity mechanism for the reactivation of rPAI-1 in vivo.  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