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   11781篇
  免费   529篇
  国内免费   138篇
耳鼻咽喉   93篇
儿科学   195篇
妇产科学   94篇
基础医学   1347篇
口腔科学   321篇
临床医学   713篇
内科学   3232篇
皮肤病学   181篇
神经病学   855篇
特种医学   457篇
外科学   2461篇
综合类   54篇
预防医学   242篇
眼科学   137篇
药学   667篇
中国医学   17篇
肿瘤学   1382篇
  2023年   97篇
  2022年   176篇
  2021年   314篇
  2020年   186篇
  2019年   214篇
  2018年   277篇
  2017年   209篇
  2016年   275篇
  2015年   285篇
  2014年   403篇
  2013年   482篇
  2012年   737篇
  2011年   833篇
  2010年   460篇
  2009年   394篇
  2008年   696篇
  2007年   720篇
  2006年   718篇
  2005年   784篇
  2004年   759篇
  2003年   711篇
  2002年   686篇
  2001年   200篇
  2000年   167篇
  1999年   214篇
  1998年   184篇
  1997年   130篇
  1996年   132篇
  1995年   87篇
  1994年   83篇
  1993年   77篇
  1992年   90篇
  1991年   71篇
  1990年   64篇
  1989年   79篇
  1988年   56篇
  1987年   47篇
  1986年   51篇
  1985年   38篇
  1984年   30篇
  1983年   29篇
  1982年   12篇
  1981年   16篇
  1980年   13篇
  1979年   19篇
  1978年   19篇
  1977年   14篇
  1971年   12篇
  1968年   11篇
  1966年   11篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
981.

Background

Balloon kyphoplasty or vertebroplasty is widely performed as a surgical intervention for osteoporotic vertebral fracture (OVF) and the effects have been investigated in many previous studies. However, the influence of the timing of the procedure on patient outcomes has not been studied formally. The purpose of this study was to investigate differences in the surgical outcomes of OVFs according to the timing of balloon kyphoplasty.

Methods

This was a multicenter cohort study. Participants comprised 72 consecutive patients who underwent balloon kyphoplasty between January 2012 and January 2016. Patients were analyzed in two groups according to the timing of kyphoplasty after onset (Early group: ≤2 months; Late group: >2 months). Follow-up continued for more than 6 months.

Results

A total of 72 patients were effectively analyzed. Of these, 27 (38%) patients underwent kyphoplasty within 2 months after symptom onset. The Late group showed greater angular motion of fractured vertebrae (p = 0.005) and compression of anterior vertebral height (p = 0.001) before surgery. Final outcomes adjusted for age and preoperative outcome showed lower visual analog scale (VAS) scores for low back pain in the Early group than in the Late group (19.9 vs. 30.4, p = 0.049). Final relative anterior vertebral height and kyphotic angle were more preserved in the Early group than in the Late group (p = 0.002 and p = 0.020, respectively), although absolute differences were not significant.

Conclusions

Vertebral height and kyphotic angle before and after balloon kyphoplasty were greater in patients who underwent kyphoplasty within 2 months after onset, and the VAS score for low back pain at final follow-up was better. Our results support kyphoplasty within 2 months.  相似文献   
982.
983.
Anti-cancer therapy with valine-depleted amino acid imbalance solution   总被引:1,自引:0,他引:1  
For the purpose of developing amino acid imbalance solution applicable to cancer treatment, we prepared seven kinds of amino acid imbalance solutions based on a 10% balanced amino acid solution and investigated the anti-tumor effects of each solution. The administration of valine-depleted amino acid solution for 8 days at a daily dose of 53 ml/rat (79.5 kcal/rat) resulted in the most significant inhibitory effects on the growth of hepatoma (AH109A) and mammary tumors (MRMT-1), the rate being 82.8% and 90.8%, respectively. Side effects observed were inhibition of increases in host body weight, weight loss of the spleen and thymus, loss of hair, and a decrease in the amounts of total plasma protein and albumin. When the daily dosage of valine-depleted amino acid solution was reduced to 40 ml/rat (58.3 kcal/rat), anti-tumor effects were still noticed, while side effects were abated. These findings indicate that side effects accompanying the use of this solution can be alleviated by controlling the ingredients of the solution as well as the amount administered. It is thus suggested that valine-depleted amino acid imbalance solution is a valuable tool in the treatment of cancer.  相似文献   
984.

Background

Long-term pitching activities change the stress distribution across the elbow joint surface in living subjects, however the influence of the different strength of stress on the stress distribution patterns remain unclear. The aims of this study were to evaluate the distribution of subchondral bone density across the elbow joint in different levels of pitchers, and to reveal the influence of the strength of stress on the elbow joint surface under long-term loading conditions of baseball pitching.

Methods

The current analysis was performed using computed tomography (CT) image data obtained from the throwing side elbow of 12 nonthrowing athletes (controls), 15 college baseball pitchers (college group) and 13 professional baseball pitchers (professional group). The distribution patterns of subchondral bone density through the articular surface of the elbow joints were assessed using a CT osteoabsorptiometry method. The quantitative analysis was based on location and percentages of high-density area on the articular surface.

Results

High-density area in the college and professional groups were found in the anterior part of the captellum, posterior part of the trochlea and radial head. In the professional group, the percentages of high-density area in the anterior part of the capitellum, posterior part of the trochlea, radial head and olecranon were significantly greater than in the college group.

Conclusions

Stress distribution on the articular surface of the elbow joint was affected by pitching abilities or competitive levels. Our analysis indicates that high strength of stress in professional baseball players produce potential risk of elbow injuries.  相似文献   
985.

Background

Hypertriglyceridemia accompanied by low levels of high-density lipoprotein cholesterol (HDL-C) is a risk factor for coronary artery disease. High-density lipoprotein 2 (HDL2) and 3 (HDL3) are believed to suppress the progress of atherosclerosis through reverse cholesterol transport. As a result, peripheral tissues can be protected against excessive accumulation of cholesterol. Although bezafibrate is known to accelerate the increase of HDL-C, results are not standardized regarding increases of HDL3 and HDL2 subfractions.

Objective

This study assessed the effects of bezafibrate on serum triglyceride (TG) fractional clearance rate (K2) and HDL2 and HDL3 cholesterol (HDL2-C and HDL3-C, respectively) levels in patients with primary hypertriglyceridemia (serum TG ≥150 mg/dL).

Methods

Outpatients with primary hypertriglyceridemia were enrolled in this 8-week study conducted at the Third Department of Internal Medicine, Nagoya City University Hospital (Nagoya, Japan). Oral bezafibrate was administered at a dose of 400 mg/d (200-mg tablet BID, morning and evening) for 8 weeks. After 8 weeks, serum levels of total cholesterol (TC), TG, HDL-C, HDL2-C, and HDL3-C were measured. A fat emulsion tolerance test to assess K2 and measurements of plasma lipoprotein lipase (LPL) mass, LPL activity, and hepatic triglyceride lipase (HTGL) activity in postheparin plasma were performed before bezafibrate administration and after the course of treatment.

Results

Sixteen patients (10 men, 6 women; mean [SD] age, 54 [12] years [range, 30-69 years]; mean [SD] body mass index, 23 [2] kg/m2) entered the study. The following findings were observed in male and female patients after 8 weeks of treatment. A statistically significant reduction was observed in mean serum TG level (P<0.01). Significant increases were seen in HDL-C, HDL2-C, and HDL3-C (all P<0.01), K2 (P<0.01), and in plasma LPL mass (P<0.01) and LPL activity (P<0.05). TC level and HTGL activity did not change significantly. No adverse effects related to the use of bezafibrate were documented.

Conclusions

In this study, bezafibrate treatment resulted in significant decreases in serum TG level and significant increases in HDL2-C and HDL3-C levels and plasma LPL mass and activity. We hypothesize that bezafibrate may increase HDL3-C by promoting TG-rich lipoprotein catabolism and may increase HDL2-C by promoting the conversion of HDL3 to HDL2.  相似文献   
986.

Background

With the increasing aging population in developed countries, there has been an associated increased prevalence of osteoporotic vertebral fracture (OVF). Many previous reports have attempted to predict the risk of delayed union associated with OVF. However, the role of endplate failure and the degeneration of adjacent intervertebral discs, and their association with delayed union has received little attention. The aim of this study was to evaluate the endplate fracture and disc degeneration rank as risk factors for delayed union.

Materials and methods

Two hundred and eighteen consecutive patients with fresh OVF were enrolled in the study. MRI and X–ray were performed at the time of enrollment and at the 6 months follow-up. The MR images were used to assess the degeneration grade of adjacent intervertebral discs (using the modified Pfirrmann grading system), and endplate failure. Supine and weight-bearing radiographs were used to define angular motion and compression ratio of the anterior vertebral body wall.

Results

A total of 139 patients (112 female, 27 male) completed the 6 month follow-up (a 65.1% follow-up rate). The study revealed 27 cases of delayed union (19.4%). A healthier adjacent caudal disc with low grade degeneration was found to be associated with an increased risk of delayed union (P = 0.008). Bi-endplate injury and significant compression of the anterior vertebral body wall were significantly associated with delayed union (P = 0.019, and P = 0.001 respectively). Rapid progression of the adjacent cranial disc degeneration was observed at the end of the 6 month follow-up period (P = 0.001).

Conclusion

Modified Pfirrmann grading system revealed that a healthier adjacent intervertebral disc at the caudal level and bi-endplate fracture were significantly associated with an increased risk of delayed union. These findings may influence the management strategy for patients with OVF.  相似文献   
987.
988.

Background/Purpose

The proximal jejunal vein which branches from the dorsal side of the superior mesenteric vein (SMV) usually drains the inferior pancreatoduodenal veins (IPDVs) and contacts the uncinate process of the pancreas. We focused on this vein, termed the proximal dorsal jejunal vein (PDJV), and evaluated the anatomical classification of the PDJV and surgical outcomes in patients with pancreatic ductal adenocarcinoma (PDAC) with PDJV involvement (PDJVI).

Methods

The jejunal veins that branch from the dorsal side of the SMV above the inferior border of the duodenum are defined as PDJVs. We investigated 121 patients who underwent upfront pancreaticoduodenectomy for PDAC between 2011 and 2017; PDJVs were resected in all patients. The anatomical classification of PDJV was evaluated using multidetector computed tomography. Surgical and prognostic outcomes of pancreticoduodenectomy for PDAC with PDJVI were evaluated.

Results

The PDJVs were classified into seven types depending on the position of the first and second jejunal veins relative to the superior mesenteric artery. In all patients, the morbidity and mortality rates were 15.7 and 0.8%, respectively. The rates for parameters including SMV resection, presence of pathological T3–4, R0 resection, and 3-year survival were 46.2, 92.3, 92.3, and 61.1%, respectively, when there was PDJVI (n?=?13). When there was no PDJVI (n?=?108), the rates were 60.2, 93.5, 86.1, and 58.3%, respectively. Overall, there were no significant differences.

Conclusions

Pancreaticoduodenectomy with PDJV resection is feasible for PDAC with PDJVI and satisfactory overall survival rates are achievable. It may be necessary to reconsider the resectability of PDAC with PDJVI.
  相似文献   
989.
Thrombomodulin (TM) is an endothelial anticoagulant cofactor that promotes thrombin-mediated formation of activated protein C (APC). We have found that the N-terminal lectin-like domain (D1) of TM has unique antiinflammatory properties. TM, via D1, binds high-mobility group-B1 DNA-binding protein (HMGB1), a factor closely associated with necrotic cell damage following its release from the nucleus, thereby preventing in vitro leukocyte activation, in vivo UV irradiation-induced cutaneous inflammation, and in vivo lipopolysaccharide-induced lethality. Our data also demonstrate antiinflammatory properties of a peptide spanning D1 of TM and suggest its therapeutic potential. These findings highlight a novel mechanism, i.e., sequestration of mediators, through which an endothelial cofactor, TM, suppresses inflammation quite distinctly from its anticoagulant cofactor activity, thereby preventing the interaction of these mediators with cell surface receptors on effector cells in the vasculature.  相似文献   
990.

Purpose

It is still unknown whether switching the bacillus Calmette-Guérin (BCG) strain at the second induction course of BCG therapy has a therapeutic benefit in patients with tumor recurrence after the initial BCG therapy (BCG-relapsing tumor).

Materials and methods

We retrospectively reviewed the clinicopathological features of 97 patients treated with a second induction course of BCG therapy between 1986 and 2014. Among the patients initially treated with BCG Tokyo-172, the second course was either BCG Tokyo-172 in 56 (57.8%) or BCG Connaught in 15 (15.5%). Among those who were initially treated with BCG Connaught, the corresponding numbers were 13 (13.4%) or 13 (13.4%), respectively. Twenty-eight (28.9%) patients were given a different BCG strain at the 2 BCG therapies (switching group), and 69 (71.1%) patients were given the same BCG strain (non-switching group).

Result

The 5-year recurrence-free survival rate of the switching group was 64.7 ± 9.6%, which was not significantly different from that of the non-switching group (54.8 ± 6.9%, P = 0.427). Switching or not switching the BCG strain was not significantly associated with tumor recurrence after the second BCG therapy. The 5-year progression-free survival rate of the switching group was 95.4 ± 2.6%, which was also not significantly different from that of the non-switching group (96.0 ± 3.9%, P = 0.674). Patients treated with BCG Tokyo-172 to Tokyo-172 had significantly higher incidences of side effects during the second BCG therapy.

Conclusions

The results of this study indicate that in patients with a BCG-relapsing tumor after the initial BCG therapy, the same BCG strain as that administered at the initial BCG therapy could be utilized effectively for the second BCG therapy. Patients treated with BCG Tokyo-172 for an initial tumor had a higher incidence of side effects during the second BCG therapy using the same strain.  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