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   12499篇
  免费   527篇
  国内免费   60篇
耳鼻咽喉   57篇
儿科学   181篇
妇产科学   116篇
基础医学   1329篇
口腔科学   259篇
临床医学   767篇
内科学   3486篇
皮肤病学   106篇
神经病学   1018篇
特种医学   521篇
外科学   2226篇
综合类   52篇
预防医学   243篇
眼科学   461篇
药学   666篇
中国医学   18篇
肿瘤学   1580篇
  2023年   72篇
  2022年   143篇
  2021年   283篇
  2020年   132篇
  2019年   202篇
  2018年   235篇
  2017年   200篇
  2016年   295篇
  2015年   279篇
  2014年   350篇
  2013年   401篇
  2012年   655篇
  2011年   686篇
  2010年   409篇
  2009年   325篇
  2008年   592篇
  2007年   601篇
  2006年   652篇
  2005年   632篇
  2004年   652篇
  2003年   635篇
  2002年   631篇
  2001年   354篇
  2000年   369篇
  1999年   331篇
  1998年   161篇
  1997年   147篇
  1996年   128篇
  1995年   123篇
  1994年   92篇
  1993年   94篇
  1992年   222篇
  1991年   186篇
  1990年   165篇
  1989年   194篇
  1988年   165篇
  1987年   109篇
  1986年   146篇
  1985年   131篇
  1984年   89篇
  1983年   86篇
  1979年   75篇
  1978年   45篇
  1977年   47篇
  1974年   47篇
  1973年   49篇
  1972年   47篇
  1971年   59篇
  1969年   41篇
  1968年   44篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
The incidence and characteristics of microbleeds in hemodialysis (HD) patients were investigated to elucidate the clinical significance with T(2)(*)-weighted gradient-echo magnetic resonance (MR) imaging. The 57 patients with chronic renal failure maintained by HD had no previous history of stroke. The control group consisted of 53 patients without previous history of stroke or chronic renal failure. The incidence and the number of microbleeds were assessed in the HD and control groups. The findings of microbleeds with T(2)(*)-weighted gradient-echo MR imaging were compared with those of T(1)- and T(2)-weighted MR imaging in HD patients. The incidence of microbleeds was significantly greater in the HD patients compared with the control patients. T(2)(*)-weighted gradient-echo imaging revealed a total of 44 microbleeds in 11 HD patients. T(2)-weighted imaging demonstrated 13 of 44 microbleeds as hyperintensity, whereas T(1)-weighted imaging demonstrated 12 lesions as hypointensity. T(2)- and T(1)-weighted imagings did not demonstrate any findings in 31 and 32 lesions, respectively. T(2)(*)-weighted gradient-echo MR imaging is effective to detect microbleeds which may be a predictor of intracerebral hemorrhage in HD patients and should be included in the protocol for the study of cerebrovascular disease, because T(2)- and T(1)-weighted MR imaging recognizes microbleeds as lacunar infarction.  相似文献   
162.
BACKGROUND CONTEXT: Although posterior lumbar interbody fusion (PLIF) for degenerative lumbar diseases is routine, there are few reports on double-level PLIF. PURPOSE: To evaluate the clinical outcomes of double-level PLIF. STUDY DESIGN/SETTING: A retrospective study of operated cases in Gifu, Japan. PATIENT SAMPLE: Nineteen patients (8 men and 11 women, 59.5+/-10.2 years) who underwent double-level PLIF between 1996 and 2001. OUTCOME MEASURES: Operation time, blood loss, complications, the Japanese Orthopaedic Association (JOA) score for back pain and lumbar sagittal alignment were evaluated. METHODS: Patients were examined retrospectively at follow-ups of 3.6+/-1.7 years. Primary diseases were spondylolisthesis, spinal canal stenosis, degenerative scoliosis and herniated intervertebral disc. Fusion areas were L3 to L5 in 15 cases and L4 to S1 in 4 cases. RESULTS: The mean JOA score increased from an initial score of 12.9+/-3.5 to 21.3+/-4.9 at the final follow-up. There was a positive correlation (R=0.718, p<.001) between the increase in lordotic angle and the increase in the JOA score. Several parameters suggested that the surgical invasiveness was not minimal. CONCLUSION: Double-level PLIF provided satisfactory results and preserved lumbar spine lordosis.  相似文献   
163.

OBJECTIVE

To investigate the effect of a free‐radical scavenger, edaravone, on the changes occurring with acute urinary retention (AUR) and subsequent catheterization in the rat bladder.

MATERIALS AND METHODS

Eight‐week‐old male Sprague Dawley rats were allocated to one of four groups; an AUR group that had urinary retention induced, with subsequent catheterization; two edaravone groups, given edaravone at 1 or 10 mg/kg body weight for 60 min and then the same urinary retention and subsequent catheterization; and a sham‐operated control group given edaravone 10 mg/kg. Urinary retention was induced by the clamping the rat penile urethra with a small clip, making a cystostomy, and then infusing 3 mL (0.6 mL/min) of saline with an infusion pump. The obstruction was sustained for 30 min and then the bladder was allowed to drain with a catheter in place for 60 min as the studies continued. After killing the rats the function of the bladder was assessed, with carbachol and 100 mm KCl, and the levels of malondialdehyde (MDA, a marker of lipid peroxidation), 8‐hydroxydeoxyguanosine (8‐OHdG; a marker of oxidative DNA damage), heat‐shock protein 70 (HSP 70) and its mRNA were measured.

RESULTS

AUR increased the intravesical pressure and decreased blood flow, and subsequent catheterization decreased the intravesical pressure and increased blood flow. Edaravone induced a decrease in blood flow in the bladder during the urinary retention and subsequent catheterization compared to the blood flow in the AUR group. Edaravone resulted in protection of the contractile responses to both carbachol and KCl in a dose‐dependent manner. The MDA concentration, 8‐OHdG content and expressions of HSP‐70 and its mRNA in the AUR group were significantly larger than those of the control group. Edaravone markedly suppressed the accumulations of MDA and 8‐OHdG in the bladder, and reduced the expressions of HSP 70 and its mRNA.

CONCLUSION

These results indicate that edaravone reduces the oxidative stress and prevents the bladder dysfunction caused by AUR and subsequent catheterization.  相似文献   
164.
Islet cell transplantation (ICTx) is one of the most effective treatments for type 1 diabetes and is less invasive compared to whole organ transplantation. The US has been the leader in the research and clinical applications of ICTx for the last 40 years. ICTx requires complex procedures, including pancreas procurement and preservation; pancreas digestion; islet purification; and transplantation. Even with the dramatic progresses in each of the procedures listed above, there are still challenges to make ICTx the standard therapy. These challenges are: (1) obtaining enough islets from a single donor and (2) preventing graft loss due to allogenic rejection and recurrence of autoimmune islet destruction. A new preservation strategy for pancreata and pancreatic ducts using ET-Kyoto solution as well as a new islet purification method using iodixanol has substantially improved islet yields. Continuous research to improve the efficacy of islet isolation will solve the issue of obtaining enough islets from a single donor. Immunological tolerance is an ideal solution for the issue of rejection and autoimmune recurrence and a regulatory T cell strategy seems promising. Moreover, the SUITO index is a simple and powerful tool to assess engrafted islet mass and is, therefore, useful for evaluating the efficacy of new immunosuppressant strategies. Once ICTx becomes a standard treatment, the donor shortage will become the next challenge. Marginal or living donor islet transplantations could help alleviate this issue; however, bio-artificial islet transplantation with animal islets could be the ultimate solution.  相似文献   
165.
This study was conducted to examine the efficacy of duct-to-mucosal pancreaticojejunostomy compared with external stented pancreaticojejunostomy in prevention of several complications, retrospectively. Seventy-six patients with pancreatic head resection (59 male; median age, 60.1 years) underwent pancreaticoduodenectomy at the Second Department of Surgery, Wakayama Medical University, School of Medicine, Wakayama, Japan, between January 1, 1994, and March 31, 2002. In early postoperative status, the incidence of pancreatic fistula by duct-to-mucosal anastomosis (n = 45) was similar to that by external stent (n = 31); soft pancreas is a risk factor of pancreatic fistula compared with hard pancreas (p < 0.05). During the late postoperative period, however, no patients with duct-to-mucosal anastomosis showed pancreatic duct dilatation by computed tomography (CT). At the same time, 58.8% of patients with external stent followed by CT showed pancreatic duct dilatation (p < 0.01). The duct-to-mucosal anastomosis was more effective pancreaticojejunostomy than the external stent in terms of prevention of pancreatic duct dilatation, and it should be the surgical procedure of choice in pancreaticoduodenectomy.  相似文献   
166.
Purpose  Patient-controlled epidural analgesia (PCEA) was developed for use after surgery for thoracic esophageal cancer to relieve wound pain, introduce early rehabilitation, and provide an uneventful postoperative recovery. Methods  This retrospective study investigated 22 patients who underwent esophageal surgery to determine the efficacy of postoperative management with PCEA. In the PCEA group (n = 12), patients had two epidural catheters inserted to cover both the thoracic and abdominal incision with a patient-controlled bolus capability. Results  Postoperative mechanical ventilation was administered in all cases in the control group (n = 10). On the other hand, this was only necessary in two patients in the PCEA group. The amount of time the patients stayed in the intensive care unit and the hospital was significantly shorter in the PCEA group than in the control group (P < 0.001 and P < 0.01, respectively). Respiratory complications occurred in four patients in the control group, and none in the PCEA group. The mean number of supplemental analgesics administered for breakthrough pain until the 7th postoperative day was 5.5 in the control group, and 1.3 in the PCEA group (P < 0.001). Conclusions  Early rehabilitation is facilitated with intensive PCEA, while it also improves postoperative management and reduces hospitalization after esophageal surgery.  相似文献   
167.

Purpose

Several video-assisted and robotic surgery techniques have been reported for resection of the thyroid and parathyroid glands. Our institute has started performing endoscopic thyroidectomy using the Lap-protector and E·Z-access system, referred to as E·Z-access using video-assisted neck surgery (EZ-VANS). In this report, we evaluate the safety and efficacy of this technique.

Methods

From January 2007 to September 2014, 110 patients underwent resection of a primary thyroid tumor, 73 who underwent a cervical collar incision (the Open group) and 37 underwent EZ-VANS (the EZ-VANS group).

Results

The average operating time was 159 and 172 min in the Open group and EZ-VANS group, respectively; the amount of blood loss was 46.5 and 54.7 ml, respectively; and the length of hospital stay after surgery was 4.3 and 5.2 days, respectively, with no significant differences observed between the two groups. The learning curve for the EZ-VANS technique was shorter than for open surgery.

Conclusions

We confirmed that the EZ-VANS technique is a safe and useful method for resection of benign and early malignant thyroid tumors.
  相似文献   
168.
Background  Sentinel nodes (SNs) are the lymph nodes that directly receive lymphatic flow from a primary cancer lesion. The SN concept implies that lymphatic metastasis initially occurs at SNs. SN navigation surgery can be introduced for cancers in which the SN concept is established. In SN navigation surgery, lymph node dissection beyond SNs can be omitted if SNs are metastasis free. Although the SN concept has been investigated frequently for oral and oropharyngeal cancer, it has so far been investigated less for laryngeal and hypopharyngeal cancer. In this study, we investigated whether the SN concept is applicable for laryngeal and hypopharyngeal cancer. Methods  Twenty patients with T2–T4 and clinically N0 laryngeal and hypopharyngeal cancer were recruited. 99mTc-phytate was injected into several sites surrounding the tumor on the day before surgery. Lymphoscintigrams were acquired from at least two different viewpoints. SNs were surveyed intraoperatively, and neck dissections including at least levels II, III, and IV were performed. Results  SNs had occult metastases in five cases. In the remaining 15 cases, neither SNs nor other lymph nodes contained metastases, consistent with the SN concept. There was one false-negative case showing delayed nodal metastasis 2 years after initial surgery. The overall accuracy of the SN concept was 95%. Conclusion  Our study shows that SN biopsy is a reliable strategy to determine correct lymph node status in N0 laryngeal and hypopharyngeal cancer. SN detection was valuable in evaluating the need for neck dissection, whether ipsilaterally or bilaterally. Presented at the 2004 Annual Meeting of the American Academy of Otolaryngology, New York.  相似文献   
169.
Purpose We compared the clinicopathologic features affecting outcome after surgery for hepatocellular carcinoma (HCC) between patients with concurrent and previous chronic hepatitis B.Methods Group A consisted of 58 patients with concurrent chronic hepatitis B, defined by seropositivity for the hepatitis B surface antigen (HBsAg), and group B consisted of 18 patients whose HCC was detected after disappearance of the HBsAg. We assessed the influence of various characteristics on outcome.Results The mean age and percentage of patients suffering from alcohol abuse or diabetes mellitus were significantly greater in group B than in group A, whereas histologic hepatitis activity, hepatic fibrosis, and alanine aminotransferase activity were significantly lower in group B than in group A. The tumor-free survival rates were similar between the two groups, but the risk factors of recurrence differed. In group A, relative youth, high aspartate aminotransferase activity, low platelet count, multiple tumors, large tumor size, portal invasion, cirrhosis, nonanatomic resection, and positive surgical margin were risk factors. In group B, large tumor size and poor differentiation were risk factors.Conclusion Hepatitis B status, tumor factors, and the type of operation affected cancer recurrence after surgery for HCC in patients with concurrent chronic HBV, as opposed to only tumor factors in patients with previous chronic hepatitis B.  相似文献   
170.
PURPOSE: Interleukin (IL)-1alpha and IL-6 levels in the cornea are greatly elevated during the early stages after an alkali burn in mice. The authors investigated the effect of synthetic inhibitor of matrix metalloproteinase (SIMP) on the expression of inflammatory cytokines in alkali-burned murine corneas and evaluated the clinical appearance of the eyes. METHODS: After 0.5N NaOH-alkali burns to 400 corneas of ICR mice, 200 received 400 microg/ml of SIMP topically 4 times a day while 200 corneas were similarly treated with vehicle only. At days 4, 7 and 14 after injury, each cornea was assigned a clinical score for corneal opacity, corneal epithelial defect, hyphema and cataract. Extracts of injured corneas in each group were then assayed for cytokine production using ELISA systems for IL-1alpha, IL-1beta, IL-6 and tumor necrosis factor-alpha (TNF-alpha). RESULTS: The levels of IL-1alpha, IL-1beta and IL-6 were significantly lower in the SIMP-treated group than in the vehicle-treated group 7 days after the burn. However, levels of these cytokines were similar in the SIMP and non-SIMP groups at days 4 and 14. Levels of TNF-alpha did not differ between both groups at any postinjury time. In the SIMP-treated corneas, there was less opacification and hyphema formation and epithelial regeneration was faster. CONCLUSIONS: Topical application of SIMP in alkali-burned murine corneas reduced the expression of IL-1alpha, IL-1beta, and IL-6 and lessened the severity of the injury.  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