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   12487篇
  免费   598篇
  国内免费   89篇
耳鼻咽喉   181篇
儿科学   242篇
妇产科学   119篇
基础医学   1615篇
口腔科学   251篇
临床医学   739篇
内科学   3416篇
皮肤病学   164篇
神经病学   1067篇
特种医学   534篇
外科学   2265篇
综合类   48篇
一般理论   2篇
预防医学   296篇
眼科学   111篇
药学   708篇
中国医学   20篇
肿瘤学   1396篇
  2024年   14篇
  2023年   90篇
  2022年   185篇
  2021年   309篇
  2020年   152篇
  2019年   250篇
  2018年   298篇
  2017年   246篇
  2016年   294篇
  2015年   319篇
  2014年   390篇
  2013年   487篇
  2012年   819篇
  2011年   832篇
  2010年   520篇
  2009年   436篇
  2008年   822篇
  2007年   895篇
  2006年   856篇
  2005年   834篇
  2004年   846篇
  2003年   789篇
  2002年   778篇
  2001年   126篇
  2000年   106篇
  1999年   125篇
  1998年   216篇
  1997年   137篇
  1996年   141篇
  1995年   88篇
  1994年   93篇
  1993年   95篇
  1992年   62篇
  1991年   50篇
  1990年   47篇
  1989年   37篇
  1988年   44篇
  1987年   39篇
  1986年   27篇
  1985年   31篇
  1984年   30篇
  1983年   33篇
  1982年   20篇
  1981年   25篇
  1980年   28篇
  1978年   18篇
  1977年   14篇
  1976年   11篇
  1975年   11篇
  1974年   10篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
PURPOSE: We describe our experience of sling removal performed after either the Vesica sling procedure (due to vaginal erosion or at the time of reoperation for recurrent stress incontinence) or the tension-free vaginal tape (TVT) procedure (due to persistent urinary retention). MATERIALS AND METHODS: From May 1997 to December 2002, we performed 19 Vesica sling procedures and 66 TVT procedures for the treatment of urodynamic stress incontinence. In the former procedures, four patients (21%) developed vaginal erosion and underwent total or partial removal of sling material (Hemashield made from bovine-collagen-injected woven polyester). In another three patients, stress incontinence recurred 2-4 years after the Vesica sling procedure, and they underwent total sling removal and the TVT procedure. Before using the urethral pull-down process (UPDP) in TVT procedures, 2 out of 23 patients (8.7%) developed persistent urinary retention and underwent either sling release alone or partial sling removal concomitant with a second TVT procedure. After the introduction of the UPDP, no patient developed urinary retention. RESULTS: Three patients in whom total sling removal was performed due to vaginal erosion after a Vesica sling procedure developed recurrent stress incontinence. One patient who underwent partial sling removal remained continent, but vaginal erosion recurred 2 years later. Patients who had total sling removal and TVT procedures due to recurrent stress incontinence after Vesica sling procedure became continent with an uneventful postoperative course. One patient who underwent transvaginal release of TVT tape (polypropylene mesh) due to urinary retention after the TVT procedure developed recurrent stress incontinence, and the other who underwent partial removal of TVT tape and a second TVT procedure had resolution of urinary retention without recurrence of stress incontinence. CONCLUSION: Prompt and total sling removal should be recommended for vaginal erosion after the Vesica sling procedure. In patients with urinary retention after the TVT procedure, partial removal of TVT tape and a second TVT procedure using the UPDP to prevent overtightness may be a preferable choice to attain both continence and resolution of urinary retention.  相似文献   
82.
BACKGROUND: Infection is a constant threat for the living-donor liver transplantation (LDLT) recipients, although little information is available on the occurrence of infection in such patients. METHODS: One hundred and thirteen consecutive LDLT recipients were prospectively followed for the presence of surgical site infections (SSIs) defined by CDC from April 2001 to March 2002. Risk factors for SSIs were evaluated by univariate and multivariate analysis. RESULTS: Of the 113 LDLT recipients, 42 (37%) developed 57 episodes of SSIs (21 intraabdominal abscess, 20 peritonitis, 8 cholangitis, and 9 wound). Of the 57 episodes, 29 (51%) had secondary bacteremia in 19 patients. Causative pathogens, including 17 episodes of polymicrobial infections, were 37 gram-positive cocci (17 Staphylococcus aureus, 16 Enterococcus spp., and 4 others), 40 gram-negative rods (25 Enterobacteriaceae, 13 Pseudomonas aeruginosa, and 4 others), and 2 Candida albicans. Univariate analysis revealed that ABO incompatibility and repeat surgery were associated with the development of SSIs. Also, univariate analysis revealed that adult recipients, ABO incompatibility, total operation duration, repeat surgery, and NNIS risk index were associated with secondary bacteremia. Multivariate analysis revealed that ABO incompatibility (OR: 14.0; 95% CI, 2.52-77.2) and repeat surgery (OR: 9.29; 95% CI, 2.00-43.1) were independently associated with secondary bacteremia. Eleven of the 42 cases (26%) who developed SSIs died. Of these 11 cases, 5 (45%) developed secondary bacteremia within 30 days before death. CONCLUSION: SSIs occurred in 37% of LDLT recipients. ABO incompatibility and repeat surgery increased the risk of developing SSIs with secondary bacteremia, which correlated with poor prognosis.  相似文献   
83.
A 57-year-old male presented with right amaurosis fugax and left transient ischemic attack caused by stenosis of the intracranial segment of the right internal carotid artery (ICA). Percutaneous transluminal angioplasty with stenting was successfully performed to dilate the stenosis. However, serial angiography revealed the development of a large pseudoaneurysm in the cervical ICA, probably as a result of carotid wall injury caused by the guiding catheter during the procedures. The patient underwent a second endovascular angioplasty. A Palmaz stent was placed across the aneurysm neck to stabilize the carotid wall. Guglielmi detachable coils were then inserted into the aneurysm cavity through the stent struts to successfully obliterate the aneurysm. Both the angiographical results and the patient's outcome were favorable. Stent-supported coil embolization is an effective and safe technique for medically refractory pseudoaneurysms, and may be a useful alternative to direct surgery.  相似文献   
84.

Background

Pancreatic cancer is an aggressive malignancy with one of the worst mortality rates of all cancers. Recently, collapsin response mediator proteins (CRMPs) were reported to be associated with proliferation, apoptosis, differentiation, and invasion in several cancers. However, CRMP expression and their role in pancreatic cancer have not been investigated. This study aimed to clarify the clinical significance of CRMPs in pancreatic cancer.

Methods

Expression of crmp genes in 11 pairs of pancreatic cancer and corresponding noncancerous pancreas tissues were examined by real-time RT-PCR. Knockdown of CRMP4 expression using siRNA was examined in pancreatic cancer cell lines to determine whether CRMP4 regulates cell proliferation and invasion in vitro. Furthermore, CRMP4 protein levels in primary tumors of pancreatic cancer (n = 53) were examined by immunohistochemistry and compared with the clinicopathological features of the tumors.

Results

Of all the CRMPs, only CRMP4 was differentially expressed in pancreatic cancer tissues (p = 0.008). CRMP4 knockdown using siRNA reduced cellular invasion, but did not affect proliferation. The expression of CRMP4 was detected immunohistochemically in 34 (64.2 %) of the 53 pancreatic cancer samples, and CRMP4 expression was correlated with severe venous invasion (p = 0.044), stage (p = 0.019), and liver metastasis (p = 0.021). Multivariate analyses suggested that venous invasion and CRMP4 overexpression were prognostic factors for survival.

Conclusions

Our results suggested that CRMP4 is significantly associated with poor prognosis by promoting liver metastasis and can serve as a novel therapeutic target for pancreatic cancer.
  相似文献   
85.

Background

Glomerular hypertension aggravates glomerular sclerosis by inducing growth factors, e.g., transforming growth factor-β (TGF-β) to mesangial matrix expansion. Smads are intracellular proteins that transmit signals from TGF-β to nucleus, and Smads are also negatively regulated by inhibitory Smads (I-Smads), Smad6 and Smad7. However, little is known about the role of I-Smads in glomerular hypertension. We studied I-Smad expression in cultured mesangial cells subjected to mechanical stretch as an in vitro model of glomerular hypertension.

Methods

Rat mesangial cells were cultured under cyclic mechanical stretch conditions using the Flexercell Strain Unit. Phosphorylated Smad1 and Smad2 were determined by Western blots. The expression of Smad6 and Smad7 mRNAs was determined by Northern blots. Stretch-mediated I-Smad mRNAs of cells pre-treated with MAPK-ERK kinase inhibitor, U0126, were also determined. Localization of phospho-Smad1, Smad6 and Smad7 proteins in the glomerulus of Dahl salt-sensitive rats was determined by immunohistochemistry.

Results

Stretch stress increased phospho-Smad1 levels, and significantly decreased Smad6 mRNA to 32?% of control, and increased Smad7 mRNA to 136?% of control. U0126 significantly attenuated stretch-mediated decreases in Smad6 mRNA, but had no effect on stretch-mediated increases in Smad7 mRNA. Phospho-Smad1, Smad6 and Smad7 proteins were localized in podocytes and mesangial cells of Dahl rats.

Conclusion

Mechanical stretch increases phospho-Smad1 levels and down-regulates Smad6 mRNA expression in mesangial cells. Stretch-mediated down-regulation of Smad6 is partially involved in ERK1/2 activation. These results indicate that glomerular hypertension might augment Smad1 signaling with concomitant attenuation of Smad6-mediated negative feedback.  相似文献   
86.
87.
OBJECTIVES Neutrophil elastase has been reported to play an important role in acute lung injury, which is a major cause of postoperative mortality after pulmonary resection. Neutrophil elastase released in the lungs reaches the peripheral circulation via the pulmonary veins. This study was performed to compare neutrophil elastase activity in pulmonary venous blood (collected during lobectomy) with that in the peripheral blood, and to determine the perioperative changes of neutrophil elastase activity. METHODS In 34 patients undergoing lobectomy with mediastinal lymph node dissection, the leucocyte count, neutrophil count, neutrophil elastase activity and levels of tumour necrosis factor-α, interleukin-6 and interleukin-8 were measured in the pulmonary venous blood and peripheral arterial blood before and after surgery. Then, these parameters were compared between before and after surgery with peripheral and pulmonary blood. RESULTS Neutrophil elastase activity was found to be significantly higher in pulmonary venous blood at the completion of surgery than at the start (during thoracotomy), while the neutrophil elastase activity of peripheral arterial blood showed no significant change between the start and completion of surgery. CONCLUSIONS In conclusion, measurement of neutrophil elastase activity in pulmonary venous blood revealed changes associated with lobectomy.  相似文献   
88.
89.
Objectives: To assess the impact of baseline lower urinary tract symptoms on postoperative urinary morbidity in patients being treated for prostate cancer with 125‐I permanent prostate brachytherapy. Methods: A total of 104 prostate cancer patients were enrolled in this study. Their urinary morbidity was followed up using the International Prostate Symptom Score and Expanded Prostate Cancer Index Composite for 12 months or more after permanent prostate brachytherapy. Patients were classified into two groups based on their baseline International Prostate Symptom Score: the low International Prostate Symptom Score group (score ≤ 7) and the high International Prostate Symptom Score group (score ≥ 8). Urinary morbidity was estimated in each group based on the results of the International Prostate Symptom Score and Expanded Prostate Cancer Index Composite measured before permanent prostate brachytherapy, and at 1, 3, 6, 9 and 12 months after the end of all radiation therapy. Results: The overall mean total International Prostate Symptom Score, International Prostate Symptom Score quality of life score, and urinary‐related scores for Expanded Prostate Cancer Index Composite were significantly worse at 1 month after the end of treatment, but they improved gradually after the treatment and recovered to the baseline level within 12 months. Even in the high‐International Prostate Symptom Score group, the International Prostate Symptom Score and International Prostate Symptom Score Quality of Life score were significantly worse at 1–3 months after permanent prostate brachytherapy, and then recovered to the baseline level without prolongation. Although the urination‐related Expanded Prostate Cancer Index Composite score in the high‐International Prostate Symptom Score group was significantly worse at 1 month after permanent prostate brachytherapy in comparison with that in the low‐International Prostate Symptom Score group, it recovered to the baseline level without prolongation. Conclusions: The present findings suggest that the presence of lower urinary tract symptoms before implantation does not prolong urinary morbidity after permanent prostate brachytherapy.  相似文献   
90.
Purpose Vascular endothelial growth factor C (VEGF-C), a novel member of the vascular endothelial growth factor family, is a relatively specific lymphangiogenic growth factor. It has been suggested that increased expression of VEGF-C in primary tumors is correlated with lymph node metastasis. We conducted this study to determine whether VEGF-C directly affects lymphangiogenesis and lymph node metastasis in colorectal cancer.Methods For an accurate analysis and clear visualization of metastases, the rectal cancer cell line, DLD1, was engineered to stably express green fluorescent protein (GFP) (DLD1/GFP). We implanted DLD1/GFP cells overexpressing VEGF-C orthotopically into the rectal walls of nude mice.Results Lymph node metastasis was confirmed in all (100%) of the mice bearing DLD1/GFP-VEGF-C tumors, but in only 25% of the mice bearing control tumors. There were more lymph node metastases per mouse in the mice bearing DLD1/GFP-VEGF-C tumors than in the mice bearing control tumors. There were no differences in cell growth and motility in vitro or in the resulting tumor volume from the implanted cells between the two groups. Immunohistochemical staining revealed that VEGF-C induced the growth of lymphatic vessels, which were enlarged in the tumor periphery and contained tumor cell emboli.Conclusion These results suggest that VEGF-C-induced lymphangiogenesis mediates tumor spread and the formation of lymph node metastasis.  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