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   1526篇
  免费   107篇
  国内免费   5篇
耳鼻咽喉   43篇
儿科学   35篇
妇产科学   34篇
基础医学   165篇
口腔科学   32篇
临床医学   146篇
内科学   289篇
皮肤病学   8篇
神经病学   127篇
特种医学   95篇
外科学   197篇
综合类   5篇
一般理论   1篇
预防医学   175篇
眼科学   5篇
药学   179篇
中国医学   3篇
肿瘤学   99篇
  2023年   22篇
  2022年   27篇
  2021年   48篇
  2020年   48篇
  2019年   44篇
  2018年   42篇
  2017年   46篇
  2016年   59篇
  2015年   62篇
  2014年   60篇
  2013年   78篇
  2012年   112篇
  2011年   103篇
  2010年   73篇
  2009年   54篇
  2008年   81篇
  2007年   60篇
  2006年   89篇
  2005年   61篇
  2004年   79篇
  2003年   82篇
  2002年   83篇
  2001年   34篇
  2000年   15篇
  1999年   22篇
  1998年   14篇
  1997年   8篇
  1996年   3篇
  1995年   9篇
  1994年   7篇
  1993年   5篇
  1992年   14篇
  1991年   12篇
  1990年   14篇
  1989年   7篇
  1988年   5篇
  1987年   9篇
  1986年   10篇
  1985年   11篇
  1984年   7篇
  1983年   2篇
  1982年   2篇
  1979年   1篇
  1978年   1篇
  1977年   3篇
  1976年   1篇
  1975年   2篇
  1974年   2篇
  1970年   1篇
  1968年   1篇
排序方式: 共有1638条查询结果,搜索用时 46 毫秒
11.
Artificial sweeteners (ASs) are calorie-free chemical substances used instead of sugar to sweeten foods and drinks. Pregnant women with obesity or diabetes are often recommended to substitute sugary products with ASs to prevent an increase in body weight. However, some recent controversy surrounding ASs relates to concerns about the risk of obesity caused by a variety of metabolic changes, both in the mother and the offspring. This study addressed these concerns and investigated the biodistribution of ASs in plasma and breast milk of lactating women to clarify whether ASs can transfer from mother to offspring through breast milk. We recruited 49 lactating women who were provided with a beverage containing four different ASs (acesulfame-potassium, saccharin, cyclamate, and sucralose). Blood and breast milk samples were collected before and up to six hours after consumption. The women were categorized: BMI < 25 (n = 20), BMI > 27 (n = 21) and type 1 diabetes (n = 8). We found that all four ASs were present in maternal plasma and breast milk. The time-to-peak was 30–120 min in plasma and 240–300 min in breast milk. Area under the curve (AUC) ratios in breast milk were 88.9% for acesulfame-potassium, 38.9% for saccharin, and 1.9% for cyclamate. We observed no differences in ASs distributions between the groups.  相似文献   
12.
Primary central nervous system lymphoma (PCNSL) is an aggressive brain disease where lymphocytes invade along perivascular spaces of arteries and veins. The invasion markedly changes (peri)vascular structures but its effect on physiological brain pulsations has not been previously studied. Using physiological magnetic resonance encephalography (MREGBOLD) scanning, this study aims to quantify the extent to which (peri)vascular PCNSL involvement alters the stability of physiological brain pulsations mediated by cerebral vasculature. Clinical implications and relevance were explored. In this study, 21 PCNSL patients (median 67y; 38% females) and 30 healthy age‐matched controls (median 63y; 73% females) were scanned for MREGBOLD signal during 2018–2021. Motion effects were removed. Voxel‐by‐voxel Coefficient of Variation (CV) maps of MREGBOLD signal was calculated to examine the stability of physiological brain pulsations. Group‐level differences in CV were examined using nonparametric covariate‐adjusted tests. Subject‐level CV alterations were examined against control population Z‐score maps wherein clusters of increased CV values were detected. Spatial distributions of clusters and findings from routine clinical neuroimaging were compared [contrast‐enhanced, diffusion‐weighted, fluid‐attenuated inversion recovery (FLAIR) data]. Whole‐brain mean CV was linked to short‐term mortality with 100% sensitivity and 100% specificity, as all deceased patients revealed higher values (n = 5, median 0.055) than surviving patients (n = 16, median 0.028) (p < .0001). After adjusting for medication, head motion, and age, patients revealed higher CV values (group median 0.035) than healthy controls (group median 0.024) around arterial territories (p ≤ .001). Abnormal clusters (median 1.10 × 105mm3) extended spatially beyond FLAIR lesions (median 0.62 × 105mm3) with differences in volumes (p = .0055).  相似文献   
13.
Acute idiopathic tubulointerstitial nephritis (TIN) is considered a condition with a good long-term prognosis. However, there is evidence that some patients develop permanent renal impairment. The aim of this study was to evaluate the clinical characteristics of TIN at the time of diagnosis in children and determine whether the findings upon presentation predict renal outcome. The clinical data and biopsy findings from 26 children with idiopathic TIN admitted to four Finnish university hospitals were analyzed retrospectively. Twenty-five patients (96%) manifested renal insufficiency. After the mean follow-up time of 2.75 years (SD 2.5; 0.9–13.5), 4 patients (15%) had permanent renal insufficiency and 8 patients (31%) had persistent low-molecular weight proteinuria. Uveitis was found in 12 patients (46%). Four of these patients (33%) developed chronic uveitis. Our analysis showed that none of the laboratory or biopsy findings upon presentation prognosticated renal outcome. No correlation between renal disease and uveitis could be found either. The occurrence of uveitis among TIN patients was higher than previously reported. Uveitis may develop late and without recurrence of renal dysfunction. Therefore, follow-up by a pediatrician and by an ophthalmologist is warranted in children with acute TIN for at least 12 months from diagnosis.  相似文献   
14.
BACKGROUND: We have employed a rat model for human acute myeloid leukemia, a promyelocytic leukemia in the BN rat strain (BNML), to develop new protocols for immunotherapy in combination with allogeneic bone marrow transplantation (alloBMT). The status of mixed chimerism in allotransplanted rats provided an opportunity for immunotherapy using alloreactive donor cells. In addition to T or natural killer (NK) cells, we introduced a second infusion of bone marrow cells as prophylactic donor lymphocyte infusions (DLI) to test whether an effective graft-versus-leukemia (GVL) response could be obtained without clinical graft-versus-host disease (GVHD). METHODS: BN rats were sublethally irradiated and transplanted with T-cell depleted bone marrow cells from either fully major histocompatibility complex (MHC)-mismatched (PVG) donor rats or MHC-matched (PVG.1N) as controls. Seven days after transplantation, rats were given 500 leukemic cells to mimic minimal residual disease. Additional cellular therapy was given at day +7. The efficiency of DLI was monitored by chimerism analysis in peripheral blood. RESULTS: Rats receiving infusions of NK cells succumbed to leukemia. T-DLI induced complete donor T-cell chimerism and lethal GVHD. A second alloBMT protected against leukemia. This effect was dependent on an MHC incompatibility between the donor and host and also on the presence of alloreactive T cells in the second bone marrow inoculum, resulting in an increased, mixed donor T-cell chimerism. CONCLUSION: A second prophylactic transplantation influenced the degree of T-cell chimerism to balance favorably between GVL and GVHD. If applicable to humans, repeated alloBMT may provide a novel approach to leukemia therapy.  相似文献   
15.
Hamstring injuries are common, especially among athletes. A complete rupture of the proximal hamstring muscles requires surgical intervention. In this report we describe a reconstruction method for a complete proximal hamstring rupture using fascia lata autograft augmentation in addition to suture anchors. This method can be advocated in cases in which the primary repair has failed or in chronic injuries where a large defect between the distally retracted tendons and the ischial tuberosity prevents anatomic reinsertion. In our technique, a muscle-tendon flap is first created from the retracted tendon stump, turned proximally, and fixed to the ischial tuberosity by suture anchors. The fascia lata graft is then fixed from the midpart to the ischial tuberosity via the same sutures. The other sleeve of the graft is folded on the ventral side of the ruptured tendon stump and fixed by use of absorbable sutures. Then the other sleeve is folded on the dorsal side and fixed in the same manner. Finally, the fixation can still be reinforced with additional absorbable sutures passing through both sleeves of the graft, as well as the muscle-tendon bridge and the tendon stump.  相似文献   
16.
17.
Objectives: The aim of this retrospective study was to compare subcuticular sutures and Steri-Strip? S in closing median sternotomy incisions in children with regard to wound healing and scar formation.

Methods: Fifty-three children and adolescents were enrolled in this study who all underwent a median sternotomy at age 0–18?years and had their presternal cutaneous wounds closed with either a running subcuticular suture (Group 1) or Steri-Strip? S (Group 2). Their scars were assessed using the Patient and Observer Scar Assessment Scale (POSAS). Secondary outcome measures were the scar measurements and the incidence of wound problems post-surgery.

Results: A significant difference was found between both groups in median POSAS observer scale scores for the items thickness (p?=?.027), pliability (p?=?.045), surface area (p?=?.045) and the total score (p?=?.048). All in favor of the subcuticular suture group. There were no significant differences concerning the POSAS patient scale scores. Middle parts of scars of patients in Group 2 were significantly broader (p?=?.001) than scars of patients in Group 1. No significant differences concerning wound problems were found.

Conclusions: There are, according to our results, no significant differences in wound healing of median sternotomy incisions in children closed with either a subcuticular suture or Steri-Strip? S. Significant differences do exist regarding scar formation and final cosmetic results of the scars, in favor of subcuticular closure.  相似文献   
18.
Transplant type for end‐stage pulmonary vascular disease remains debatable. We compared recipient outcome after heart‐lung (HLT) versus double‐lung (DLT) transplantation. Single‐center analysis (38 HLT–30 DLT; 1991–2014) for different causes of precapillary pulmonary hypertension (PH): idiopathic (22); heritable (two); drug‐induced (nine); hepato‐portal (one); connective tissue disease (four); congenital heart disease (CHD) (24); chronic thromboembolic PH (six). HLT decreased from 91.7% [1991–1995] to 21.4% [2010–2014]. Re‐intervention for bleeding was higher after HLT; (P = 0.06) while primary graft dysfunction grades 2 and 3 occurred more after DLT; (P < 0.0001). Graft survival at 90 days, 1, 5, 10, and 15 years was 93%, 83%, 70%, 47%, and 35% for DLT vs. 82%, 74%, 61%, 48%, and 30% for HLT, respectively (log‐rank = 0.89). Graft survival improved over time: 100%, 93%, 87%, 72%, and 72% in [2010–2014] vs. 75%, 58%, 42%, 33%, and 33% in [1991–1995], respectively; P = 0.03. No difference in chronic lung allograft dysfunction (CLAD)‐free survival was observed: 80% & 28% for DLT vs. 75% & 28% for HLT after 5 and 10 years, respectively; = 0.49. Primary graft dysfunction in PH patients was lower after HLT compared to DLT. Nonetheless, overall graft and CLAD‐free survival were comparable and improved over time with growing experience. DLT remains our preferred procedure for all forms of precapillary PH, except in patients with complex CHD.  相似文献   
19.

Introduction

In laparoscopic colorectal cancer surgery, some authors still report increased conversion rates, operative duration and postoperative morbidity with longer hospital stay in obese patients. In our department, we had the impression that laparoscopic surgery in the obese was feasible and safe, leading to this study in which we evaluate laparoscopic surgery for colorectal cancers in the obese and measure the impact on short-term results.

Material and Methods

In the period from November 2004 to May 2010, 425 patients were laparoscopically operated for a colon or rectal cancer in our center. Ninety-three patients had a body mass index (BMI)????30. Demographic data and short-term outcome in patients with a BMI????30 were compared to the same data in patients with a BMI?<?30.

Results

The median operative time was significantly longer (240 vs. 225?min, p?=?0.021) and the mean blood loss was significantly higher (348 vs. 285?ml, p?=?0.034) in the group of patients with BMI????30. No other significant differences, including conversion to open surgery and postoperative morbidity, were found between the two groups.

Conclusion

Laparoscopic colorectal cancer surgery is feasible and safe in obese patients with a BMI above 30, without the patients experiencing an increased risk of postoperative morbidity or mortality.  相似文献   
20.
Twenty-four primary elbow synovectomies were done between 1991 and 1998 at the authors' institution on 19 patients (15 females, four males) with juvenile rheumatoid arthritis. Five bilateral and 14 unilateral procedures were done. The mean age of the patients was 29 years (range, 11-64 years) at the time of surgery and the mean disease duration was 19 years (range, 2-51 years). Preoperatively radiographic destruction of Larsen Grade 1 was detected in 21% of elbows, Grade 2 in 54%, and Grade 3 in 4%. In 21% of elbows no radiographic destruction was present (Grade 0). The cumulative survival rate of elbow synovectomy was 84% (95% confidence interval, 68-98) at 5 years. Four resynovectomies and two elbow replacement arthroplasties were done during the followup period. Complete pain relief was documented in 44% of patients and subjective outcome was excellent or good in 72% of patients. No significant improvement was observed in functional ability or range of motion in extension and flexion or pronation and supination. The results of the current study (mean followup, 5 years; range, 2-9 years) are slightly worse compared with the short-term results of elbow synovectomy in patients with adult-onset rheumatoid arthritis.  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