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   7718篇
  免费   680篇
  国内免费   11篇
耳鼻咽喉   364篇
儿科学   468篇
妇产科学   373篇
基础医学   479篇
口腔科学   536篇
临床医学   714篇
内科学   1581篇
皮肤病学   198篇
神经病学   675篇
特种医学   267篇
外科学   1618篇
综合类   62篇
一般理论   1篇
预防医学   245篇
眼科学   257篇
药学   354篇
中国医学   25篇
肿瘤学   192篇
  2024年   21篇
  2023年   207篇
  2022年   138篇
  2021年   313篇
  2020年   227篇
  2019年   270篇
  2018年   584篇
  2017年   461篇
  2016年   583篇
  2015年   426篇
  2014年   681篇
  2013年   845篇
  2012年   734篇
  2011年   760篇
  2010年   593篇
  2009年   293篇
  2008年   247篇
  2007年   206篇
  2006年   198篇
  2005年   147篇
  2004年   75篇
  2003年   76篇
  2002年   70篇
  2001年   83篇
  2000年   57篇
  1999年   41篇
  1998年   32篇
  1997年   14篇
  1996年   7篇
  1995年   3篇
  1994年   5篇
  1993年   3篇
  1990年   3篇
  1989年   2篇
  1987年   2篇
  1981年   1篇
  1928年   1篇
排序方式: 共有8409条查询结果,搜索用时 31 毫秒
31.
Chest wall involvement is an uncommon manifestation of musculoskeletal tuberculosis. We present computed tomography and magnetic resonance imaging findings in a case with multifocal musculoskeletal tuberculosis presenting as a breast mass. These radiological modalities are not diagnostic without histopathological confirmation, but they are valuable guides to surgery in defining the extent of disease involvement. Received: 1 July 1998; Revision received: 8 October 1998; Accepted: 12 October 1998  相似文献   
32.
Free-radical generation and nitric oxide (NO) generation were detected in the rat bladder following acute bladder outlet obstruction (BOO), and the results were compared with those for vascular ischemia and reperfusion (I-R). Forty male Sprague Dawley rats were used. In the acute BOO plus I-R group (group 1), rats were catheterized with a 3-Fr catheter and an inflated balloon was positioned at the bladder neck. The bladder was overdistended after administration of Ringer solution and furosemide (12 mg/kg, each) for 60 min, and was then drained to allow reperfusion for 30 min. In the acute BOO plus nerve stimulation group (group 2), the pelvic nerve was stimulated in the distended bladder for 60 min (5 s every 5 min, 10 V/0.1 ms, 20 Hz). Pelvic nerve stimulation was performed in nonobstructed animals in group 3. In the I-R group (group 4), the distal aorta was occluded for 60 min followed by reperfusion for 30 min. Sham-operated animals served as the control group (group 5). At the end of the protocols, the levels of hydroxyl and superoxide radicals and NO levels were measured in the bladder tissues with luminol- and lucigenin-enhanced chemiluminescence methods. The results were compared by a one-way analysis of variance test. The levels of hydroxyl radicals were not significantly different between the study groups. In contrast, superoxide radicals and NO levels were significantly increased in both group 1 and group 4 compared with those in control animals (P < 0.05 for all comparisons). Superoxide radical generation in group 2 was comparable to the levels in group 1 (P > 0.05), whereas NO levels were substantially lower than in group 1 (P = 0.06). In summary, vascular I-R causes significant oxidative damage to the bladder. Acute BOO with overdistension of the bladder mimics the effects of true vascular I-R injury. The NO pathway has possibly a major role in I-R-induced bladder damage. Prolonged BOO may therefore significantly enhance the oxidative damage to the bladder and further accentuate the effects of generalized atherosclerotic processes in the elderly adult.  相似文献   
33.
34.
Although, one out of every eight women has a risk of developing breast cancer, the reported incidence of breast carcinoma detection in reduction mammaplasty materials is rather low. To our knowledge, specimen radiography, which is used for breast biopsies has not been used for the assessment of breast reduction materials. We investigated the applicability of specimen radiography and its potential benefits in detection of the breast pathologies, especially malignancies in reduction mammaplasty materials. Forty patients scheduled for reduction mammaplasty operation were included. In all cases an inferior pedicle reduction technique was preferred and the radiographs of the resected breast tissues were taken immediately. The radiographs were evaluated for any possible pathologic appearance and all abnormal findings were marked. For the histopathologic evaluation, in addition to the random sampling of the pathologist, any marked areas were also microscopically examined. In two cases fibrocystic changes were found in radiographs and the same results were obtained in the histological examination. No false negative mammogram was seen. Specimen radiography, which is applicable for breast reduction materials is an easy and cheap method and does not cause any patient discomfort. It seems that the radiographs of reduction mammaplasty materials are useful to provide guidance to the pathologist during tissue sampling for microscopic examination especially when large amounts of breast tissue is excised.  相似文献   
35.
Patients with erectile dysfunction, who admitted to 4 different urological centres in Turkey were evaluated in terms of aetiological factors to establish the aetiology of erectile dysfunction in our population and compare it with the data derived from Western communities. After the history, physical examination, psychological evaluation and laboratory testing, a clinical diagnosis was established as primarily psychogenic, organic, or mixed aetiology. Mean patient age was 43.5 years (range 17 to 69), and 9 of the patients were unmarried. Of the patients 53 had vascular risk factors, and 10 reported a history of alcohol abuse. Eleven patients were using drugs that might interfere with the disorder. In this multicentral study of 115 impotent men, an organic cause was found in 43%, psychogenic in 47%, and mixed in 19%. Mean age of the overall patients was 43.48. When the ages of the patients with organic erectile dysfunction and those with psychogenic erectile dysfunction were compared, it was clearly seen that those with organic erectile dysfunction were much older (52.73 versus 33.02). This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   
36.
Management of Esophageal Perforation   总被引:12,自引:0,他引:12  
Despite recent advances in thoracic surgery, the management of esophageal perforation remains problematical and controversial. Thirty-one patients were treated for an esophageal perforation between 1986 and 1998. The esophageal perforation was iatrogenic in 25 cases, spontaneous in 2, traumatic in 2, and caused by a tumor and tuberculous lymphadenitis in 2 patients. There were 10 cervical, 19 thoracic, and 2 abdominal perforations. The interval from perforation to operation was less than 24 h in 12 patients and more than 24 h in 19 patients. The surgical procedures included a primary repair in 12 patients, a resection in 8, and conservative treatment with minor surgical approaches in 11. The mortality rate was 20% (4/20 patients) in the surgical treatment group and 45.5% (5/11 patients) in the conservative treatment with minor surgery group. The overall mortality was 29% (9/31 patients). The prognosis is thus concluded to depend on the cause and location of the perforation, the presence of underlying esophageal diseases, and the surgical procedure chosen. Received: October 12, 1999 / Accepted: May 30, 2000  相似文献   
37.
Renal scarring due to pyelonephritis was shown to improve in rats given vitamin A. We evaluated the effect of vitamin A in a renal ablation nephropathy model. Four groups, each including 7 rats with 5/6 nephrectomy, were formed: group I (no vitamin A), group II (60 kIU vitamin A), group III (120 kIU vitamin A), and group IV (180 kIU vitamin A). Four sham-operated rats comprised the control group. After 6 weeks of 5/6 nephrectomy, the rats were sacrificed and serum creatinine, vitamin A, and β-carotene levels were determined in addition to histopathological evaluation of the remnant kidneys. The tubulointerstitial and glomerular changes were graded as ”0–3” and ”0–5” respectively, in accordance with the severity of the lesions. Tubulointerstitial score (TIS), mean glomerulosclerosis score (MGS, arithmetical mean of the sclerosis scores of 100 glomeruli), and severity of glomerulosclerosis index (SGI, ratio of the number of glomeruli with grade ≥3 sclerosis to the total number of glomeruli examined) were calculated for each rat. Serum creatinine levels were higher in the study groups than the control rats (P<0.05), but there was no significant difference between the study groups (although the levels increased as the dose of vitamin A increased). Serum vitamin A levels were significantly higher in the groups given vitamin A than the control rats and group I (P<0.05). In addition, serum vitamin A levels increased significantly in parallel to increasing doses of vitamin A (P<0.05). Serum β-carotene levels did not differ between the groups, except for group II, which had lower levels than controls (P=0.01). MGS and SGI were significantly higher in the study groups than control rats (P<0.05), but did not differ between the study groups. Study and control rats were not different with respect to TIS, but there was a difference between the control group and group III (P=0.04). Group II had the lowest MGS, SGI, and TIS scores among the study groups. When all the rats were considered together, vitamin A levels did not correlate with the MGS and SGI, but correlated positively with the TIS (r=0.391, P=0.027). β-Carotene levels also did not correlate with the MGS, SGI, and TIS. In conclusion, vitamin A administration did not significantly affect the clinical and pathological course of renal ablation nephropathy in rats. Furthermore, higher doses of vitamin A might even damage renal tissue. Received: 14 June 1999 / Revised: 2 December 1999 / Accepted: 2 December 1999  相似文献   
38.
Background The aim of the present study was to identify the clinicopathological factors affecting locoregional recurrence (LRR) in patients with clinical stage IIIB noninflammatory breast cancer (NIBC). Methods The records of 120 stage IIIB NIBC patients treated with neoadjuvant chemotherapy (NAC) and then modified radical mastectomy followed by radiotherapy were evaluated. In this retrospective cohort, the effects of age, menopausal status, clinical tumor size, clinical response to NAC, pathological axillary status, number of positive axillary lymph nodes, pathological response to NAC, grade, lymphovascular invasion, estrogen receptor status, progesterone receptor status, Her-2-neu status, and p53 status on LRR were evaluated by univariate and multivariate analyses. Results The clinical response rate of 120 patients was 79.2% (17.5% complete and 61.7% partial), with a complete pathological response rate of 12.5%. The median follow-up was 28 months (range: 10–74 months). The LRR rate was 13.3%. Based on the univariate analysis, the clinical tumor size, clinical response rate, pathological axillary status, four or more positive axillary lymph nodes, lymphovascular invasion, and estrogen receptor status were factors that significantly affected LRR. In the multivariate analysis, however, only the clinical response rate and the number of positive axillary lymph nodes were found to be statistically significant independent factors. Conclusions Effective local control of disease can be achieved in patients with stage IIIB NIBC using a combination of NAC, surgery, and radiotherapy. However, a worse clinical response after chemotherapy and four or more positive axillary lymph nodes affect LRR negatively in these patients.  相似文献   
39.

Objectives

To investigate carbohydrate antigen (CA 19-9, CA 15-3, and CA 125) levels in the patients who had hydronephrosis with renal stones and in whom Extracorporeal shock wave lithotripsy (ESWL) was performed.

Materials and Methods

This prospective study included 20 people with no known disease for control group and 30 patients who had hydronephrosis with renal stones and in whom ESWL was performed between January 2005 and January 2006. None of patients had urinary infection and malignancy. The blood for carbohydrate antigens was taken pre-ESWL and 30 min after ESWL in both groups. CA 19-9, CA 15-3, and CA 125 in the serum were tested with the electro-immunoassay method on the Roche® E-170 apparatus with the original Roche® kit.

Results

The CA 19-9 and CA 125 values in the patients group were found to be statistically significant when compared with the control group but the CA 15-3 was not found to be significant. However, CA 19-9, CA 15-3, and CA 125 values of post-ESWL were not statistically significant when compared with pre-ESWL group (P > 0.05).

Conclusions

The average serum values of CA 125 and CA 19-9 in patients were found to be significantly high. However, serum values of CA 19-9, CA 15-3, and CA 125 were not affected by ESWL.
  相似文献   
40.
Objective To evaluate the relationship between the expression of E-cadherin (E-CD) and tumor recurrence and progression in patients with high-grade stage T1 urothelial carcinoma of bladder. Methods Fifty-two patients who had primary high-grade stage T1 urothelial carcinoma were enrolled to the study. The pathologic specimens of patients were evaluated and staged as T1a and T1b according to muscularis mucosae involvement by the tumor. The immunohistochemical demonstration of E-CD was accomplished by using immunoperoxidase method and all the specimens were examined under light microscope for E-CD level. Results The mean age of the patients was 64.0 ± 7.7 (range 36–81) years. The mean follow-up period was 56.4 ± 19.4 (range 14–84) months. Among 52 patients, 27 (52%) of them were stage T1b and 25 (48%) were T1a tumors. The recurrence rates for T1a and T1b groups were 52% (n = 13) and 92.6% (n = 25), respectively (P < 0.05). The expression of E-CD was homogenous in 52% of pT1a and 14.8% of T1b tumors (P < 0.05). In T1a group with recurrence, homogeneous E-CD staining ratio was 30.7% (n = 4/13), but it was 75% (n = 9/12) in T1a patients without recurrence (P < 0.05). In T1b group with recurrence, the homogenous expression of E-CD was 12% (n = 3/25) and the expression of E-CD was heterogenous in 88% (n = 22/25) of them (P < 0.05). In T1a group, progression of the disease was detected in 28% (n = 7/25) of the patients, but disease progression was seen in 55.5% (n = 15/27) of T1b group patients (P < 0.05). In T1a group with progression, heterogeneous E-CD staining ratio was 85.7% (n = 6/7), but it was 80% (n = 12/15) in T1b patients with progression. The effects of tumor number, tumor size and carcinoma in situ presence on recurrence were evaluated within each group. It was determined that parameters such as tumor number and tumor size had no significant effect on recurrence of the groups. The mean survival rates were statistically different between the groups. On multivariate analysis only E-cadherin expression (P = 0.012, odds ratio 6.291, 95% confidence interval for odds ratio 1.303–4.72) and tumor stage (P = 0.003, odds ratio 11.58, 95% confidence interval for odds ratio 2.446–8.542) remained independently significant as predictors of recurrence. Conclusion E-CD expression was decreased in pathologic specimens of bladder tumor patients with muscularis mucosae involvement and this condition correlated well with tumor recurrence.  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