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   4434篇
  免费   175篇
  国内免费   38篇
耳鼻咽喉   128篇
儿科学   215篇
妇产科学   121篇
基础医学   304篇
口腔科学   157篇
临床医学   335篇
内科学   1093篇
皮肤病学   76篇
神经病学   303篇
特种医学   185篇
外科学   973篇
综合类   90篇
一般理论   1篇
预防医学   205篇
眼科学   100篇
药学   166篇
中国医学   9篇
肿瘤学   186篇
  2023年   42篇
  2022年   59篇
  2021年   125篇
  2020年   69篇
  2019年   98篇
  2018年   124篇
  2017年   74篇
  2016年   141篇
  2015年   132篇
  2014年   155篇
  2013年   252篇
  2012年   340篇
  2011年   329篇
  2010年   178篇
  2009年   158篇
  2008年   330篇
  2007年   346篇
  2006年   357篇
  2005年   315篇
  2004年   286篇
  2003年   216篇
  2002年   185篇
  2001年   21篇
  2000年   25篇
  1999年   18篇
  1998年   6篇
  1997年   6篇
  1996年   10篇
  1995年   6篇
  1992年   17篇
  1991年   8篇
  1990年   13篇
  1989年   7篇
  1988年   15篇
  1987年   14篇
  1986年   16篇
  1985年   25篇
  1984年   13篇
  1983年   8篇
  1982年   9篇
  1981年   6篇
  1980年   7篇
  1979年   13篇
  1978年   8篇
  1976年   5篇
  1974年   9篇
  1972年   8篇
  1970年   4篇
  1969年   6篇
  1968年   6篇
排序方式: 共有4647条查询结果,搜索用时 15 毫秒
31.
BACKGROUND: The encouraging results of valve repair in the atrioventricular valves have influenced a decision about aortic valve (AV) reconstruction. We report our experience with pericardial cusp extension to repair rheumatic AV disease. METHODS: From 1993 to 1998, 46 patients (25 women, 21 men) with a mean age of 31.5 +/- 12.2 years (range, 15 to 58 years) underwent AV repair. Twenty-two (47.8%) patients had moderate and 24 (52.2%) had severe aortic insufficiency (AI). Severe cusp retraction was repaired with glutaraldehyde-treated autologous pericardium. Twenty-one patients had more than one maneuver (mean, 1.8) to attain competence besides augmentation, which consisted of the release of stenotic commissures (in 11 cases), thinning of the AV cusps (in 10 cases), and resuspension of the cusps (in 17 cases). Simultaneous mitral valve repair was performed on 17 patients. Eight patients received triple valve reconstruction. RESULTS: There was no early mortality. Thirty patients no longer had AI with any significant transvalvular gradients. Five patients were followed with mild residual AI, and 2 patients with moderate AI not requiring reoperation. Nine patients developing severe AI required AV replacement with a reoperation rate 19.6% (4.26%/patient-year). The mean interval between repair and reoperation was 28.2 +/- 18.3 months (range, 3 to 58 months). The mean observation time was 4.6 +/- 3 years (211.6 patient-years). Late mortality rate was 2.2% with 1 patient. The significant negative predictors of aortic reoperation determined by univariate analysis were preoperative New York Heart Association class (p = 0.002) and postoperative severe AI (p < 0.001). Cox hazard studies identified that all risk factors were insignificant for aortic reoperation. The actuarial rate of freedom from aortic reoperation was 76.1% +/- 7% at 7.5 years. CONCLUSIONS: Although AV repair by extension with pericardium is worth considering with an acceptable solution to achieve a good geometry from unequal cusps, especially in young rheumatic patients for preservation of the native AV, the patients should be followed periodically for reoperation risk.  相似文献   
32.
Differential expression of hZnT-4 in human prostate tissues   总被引:2,自引:0,他引:2  
BACKGROUND: Altered zinc levels in prostate benign prostatic hyperplasia (BPH) and carcinoma is well documented. It is not known whether loss of zinc, necessary to restrain aggressive growth, results from loss of a single specific or multiple zinc transporters. METHODS: Human prostate tissues from patients who underwent radical prostatectomy were screened by RT-PCR analysis for five zinc transporters. Relative cDNA expression was determined in normal, BPH, and tumor specimens and four prostate epithelial cell lines. RESULTS: Surgical specimens were obtained from patients with assigned Gleason scores ranging from 5 to 9. Relative expression of hZIP-1 and hZnT-1 were prominent in most samples with relatively lesser degree of expression of hZIP-2 and no detectable expression of hZnT-3. Expression of hZnT-4 was decreased in BPH and tumor samples compared to normal tissue. CONCLUSIONS: These data suggest that zinc homeostasis in normal prostate tissues results from an interplay of multiple transporters and decreased hZnT-4 expression is associated with prostate tissue abnormalities independent of total cellular zinc content.  相似文献   
33.
A 39-year-old woman with three children presented with primary severe urinary incontinence. Epispadias without exstrophy was determined in physical examination. The single-stage procedure including vulvoplasty and modified Young-Dees-Leadbetter bladder neck repair was performed to obtain sufficient cosmetic outcome and continence. Excellent functional and cosmetic results were obtained.  相似文献   
34.
BACKGROUND: Reperfusion of the liver after ischemia induces the expression of the heat shock genes and the synthesis of the heat shock proteins (HSP). We studied the effects of the natural antioxidant ergothioneine (EGT) treatment on the expression of HSP70 in ischemic-reperfused (IR) liver. METHODS: Adult male Wistar rats were randomly divided into three groups: Sham group given standard laboratory chow and water for 3 weeks followed by sham operation; Control group given standard laboratory chow and water for 3 weeks followed by liver IR injury; EGT group given standard laboratory chow supplementation l-ergothioneine (1.2 mg/kg/d body weight) administered by gavage and water for 3 weeks followed by liver IR injury. Ten rats from each group were killed to determine serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactic dehydrogenase (LDH), tissue malondialdehyde (MDA), HSP70 levels, and histologic changes at 30, 60, and 120 min of reperfusion, respectively. Survival was followed for 1 week. RESULTS: IR caused significant increase in serum AST, ALT, LDH, and tissue MDA levels. As compared with the control group, animals treated with EGT experienced a significant decrease in serum AST, ALT, and LDH levels in all reperfusion periods. Tissue MDA levels in animals receiving EGT were significantly reduced as compared with control group at 30 min and 60 min after reperfusion. After ischemia, reperfusion caused a remarkable production of HSP70 in the control group. When the rats were pretreated with EGT, the levels of HSP70 increased significantly in their livers after reperfusion compared with the control group. Liver injury in the EGT-treated animals was lower to that in the control group. The 7-day survival rate was significantly improved (from 50% to 80%) by EGT pretreatment. CONCLUSION: HSP70 has been shown to induce tolerance against warm IR injury in rat livers. EGT pretreatment protects the liver from IR injury by over-expression of HSP and the subsequent suppression of lipid peroxidation.  相似文献   
35.
The aim of this study was to assess the capacity of simple alginate capsules to protect adult pig islets in a model of xenotransplantation. Adult pig islets were microencapsulated in alginate, with either single alginate coats (SAC) or double alginate coats (DAC), and transplanted into the streptozotocin-induced diabetic B6AF1 mice. Normalization of glucose levels was associated with an improvement of the glucose clearance during intravenous glucose tolerance tests. After explantation, all mice became hyperglycemic, demonstrating the efficacy of the encapsulated pig islets. Explanted capsules were mainly free of fibrotic reaction and encapsulated islets were still functional, responding to glucose stimulation with a 10-fold increase in insulin secretion. However, a significant decrease in the insulin content and insulin responses to glucose was observed for encapsulated islets explanted from hyperglycemic mice. An immune response of both IgG and IgM subtypes was detectable after transplantation. Interestingly, there were more newly formed antibodies in the serum of mice transplanted with SAC capsules than in the serum of mice transplanted with DAC capsules. In conclusion, alginate capsules can prolong the survival of adult pig islets transplanted into diabetic mice for up to 190 days, even in the presence of an antibody response.  相似文献   
36.
Priapism is defined as a prolonged and persistent erection of the penis without sexual stimulation. This is a poorly understood disease process with little information on the pathophysiology of this erectile disorder. Complications from this disorder are devastating due to the irreversible erectile damage and resultant erectile dysfunction (ED). Stuttering priapism, though relatively rare, affects a high prevalence of men with sickle-cell disease (SCD) and presents a challenging problem with guidelines for treatment lacking or resulting in permanent ED. The mechanisms involved in the development of priapism in this cohort are poorly characterized; therefore, medical management of priapism represents a therapeutic challenge to urologists. Additional research is warranted, so we can effectively target treatments for these patients with prevention as the goal. This review gives an introduction to stuttering priapism and its clinical significance, specifically with regards to the patient with SCD. Additionally, the proposed mechanisms behind its pathophysiology and a summary of the current and future targets for medical management are discussed.  相似文献   
37.

Aim

We analyzed the outcomes and effectiveness of surgical treatments and clinical manifestations of splenic hydatid cysts.

Patients and Methods

Between 2000 and 2011, we retrospectively reviewed the cases of 11 patients who were operated on for a splenic hydatid cyst. The demographic features, medical history, physical examinations, biochemical and serological tests, imaging modalities, and surgical treatment of the patients were noted.

Results

The mean patient age was 36.45?years (range, 20?C66?years). While isolated splenic hydatid disease was present in five patients, other abdominal hydatid cysts were accompanied by a splenic hydatid cyst in six patients. Left upper abdominal pain was present in seven (64%) patients, whereas four (36%) patients were asymptomatic. Eight patients (72.72%) had undergone a total splenectomy and three (27.28%) had undergone spleen-preserving surgery. Postoperative complications developed in four (36%) patients at 5?C15?days postoperatively.

Conclusion

Management of a splenic hydatid cyst is not consensual. Total splenectomy is optimal because it provides definitive treatment. However, spleen-preserving surgery is the preferred treatment in selected patients. The choice of technique depends on the localization, number, and size of hydatid cysts, and the absence or presence of other hydatic organ cysts.  相似文献   
38.
Isolated scaphoid dislocations are very rare. Options for the treatment of dislocation of the scaphoid include closed reduction and casting, closed reduction and percutaneous pinning, and open reduction and ligament repair. We report a case of this rare injury which was treated with open reduction, pinning and ligament repair.  相似文献   
39.
INTRODUCTIONIntraabdominal bands of the vitelline vessel remnant are the rarest form of congenital mesodiverticluar bands which may or may not be associated with Meckel's diverticulum. In the majority of cases they cause an acute abdominal disease such as intestinal obstruction, especially in children.PRESENTATION OF CASEWe report a case of a 64 year old gentleman who experienced recurrent episodes of abdominal distension and bloating over two years. Computed tomography of his abdomen, colonoscopy, and barium follow through were all normal. Diagnostic laparoscopy revealed a single band adhesion stretching between the distal ileal mesentery and the anterior abdominal wall near the umbilicus.DISCUSSIONCongenital vascular bands are established causes of acute intestinal obstruction especially in children but are relatively uncommon. Their role in chronic abdominal pain is rare and diagnosis is difficult preoperatively. Pain in the patient was most likely due to recurrent partial twisting and untwisting of the bowel around the band.CONCLUSIONThis case not only highlights an unusual cause of chronic abdominal pain, but also the effectiveness of laparoscopy as a diagnostic tool in such patients.  相似文献   
40.
Does sodium nitroprusside reduce lung injury under cardiopulmonary bypass?   总被引:4,自引:0,他引:4  
Objective: We hypothesized that direct pulmonary arterial infusion of sodium nitroprusside (SNP) would ameliorate lung injury under cardiopulmonary bypass. Methods: Experiments were performed on 12 adult mongrel dogs of both sexes weighing 20–28 kg. The animals were randomly divided into two groups of six animals each. All animals were subjected to total cardiopulmonary bypass (CPB) and moderate hypothermia (28°C core temperature). During total CPB, the aorta was clamped together with the pulmonary artery to prevent any antegrade flow to the lungs. After cardioplegic arrest for 120 min, the animals were rewarmed, weaned from CPB, and their condition stabilized for another 90 min. After the release of the aortic cross-clamp, the dogs received either a 5% glucose solution as a placebo (group I) or SNP (0.5 μg/kg per min) (group II), both infused into the pulmonary arterial line. The infusion was stopped after 60 min. To measure lung tissue malondialdehyde (MDA), water content and polymorphonuclear leukocytes count, lung tissue samples were taken before CPB and after weaning from CPB. In addition, alveolar-arterial oxygen difference (AaDO2) for tissue oxygenation was calculated by obtaining arterial blood gas samples. Results: Values of MDA before CPB of 42.0±5.3 nmol/g of tissue rose to 67.6±5.7 nmol/g of tissue after weaning from CPB in group I (P=0.028). In group II MDA values also increased from 43.1±4.3 to 52.4±5.7 nmol MDA/g of tissue after weaning from CPB (P=0.046). The MDA increase in group II after CPB was found to be significantly lower than that for group I (P=0.004). The wet-to-dry lung weight ratio in the sodium nitroprusside group was 5.1±0.2, significantly lower than in the control group (6.8±0.4), (P=0.01). AaDO2 increased significantly in group I (P=0.028). There was no statistically significant difference (P=0.065) between groups I and II. During histopathological examination it was observed that neutrophil counts in the lung parenchyma rose significantly after CPB in both groups. The increase in group I was significantly larger than that in group II (P<0.001). Conclusions: The results represented in our study indicate that pulmonary arterial infusion of sodium nitroprusside during reperfusion can reduce lung injury under cardiopulmonary bypass.  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