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   2321篇
  免费   89篇
  国内免费   12篇
耳鼻咽喉   107篇
儿科学   115篇
妇产科学   71篇
基础医学   143篇
口腔科学   137篇
临床医学   228篇
内科学   431篇
皮肤病学   13篇
神经病学   87篇
特种医学   162篇
外科学   516篇
综合类   48篇
预防医学   83篇
眼科学   44篇
药学   82篇
中国医学   6篇
肿瘤学   149篇
  2023年   21篇
  2022年   32篇
  2021年   70篇
  2020年   43篇
  2019年   41篇
  2018年   86篇
  2017年   53篇
  2016年   79篇
  2015年   81篇
  2014年   125篇
  2013年   117篇
  2012年   158篇
  2011年   136篇
  2010年   72篇
  2009年   68篇
  2008年   136篇
  2007年   174篇
  2006年   149篇
  2005年   137篇
  2004年   140篇
  2003年   105篇
  2002年   97篇
  2001年   67篇
  2000年   51篇
  1999年   52篇
  1998年   18篇
  1997年   9篇
  1996年   8篇
  1995年   6篇
  1994年   3篇
  1992年   10篇
  1991年   7篇
  1990年   3篇
  1989年   3篇
  1988年   7篇
  1987年   5篇
  1985年   4篇
  1984年   2篇
  1983年   2篇
  1982年   2篇
  1981年   3篇
  1979年   4篇
  1978年   2篇
  1972年   4篇
  1970年   2篇
  1969年   4篇
  1968年   2篇
  1967年   2篇
  1966年   4篇
  1955年   2篇
排序方式: 共有2422条查询结果,搜索用时 15 毫秒
101.
The free radical copolymerization of 2-thienylmethyl 4-vinylbenzyl ether (TMVBE) with 2-oxo-2-(2-thienylmethoxy)ethyl-2-methylacrylate (TMOEM) has been carried out in 1,4-dioxane at 65?°C?±?1 and were analyzed by Fourier transform infrared, 1H NMR, and 13C NMR spectroscopy. 1H NMR analysis was used to determine the molar fractions of TMVBE and TMOEM in the copolymers. The monomer reactivity ratios were calculated according to the general copolymerization equation using Kelen–Tüdõs and Finemann–Ross linearization methods. The reactivity ratios indicated a tendency toward alternation copolymerization. The thermal behaviors of copolymers with various compositions were investigated by differential scanning calorimetry and thermogravimetric analysis. Also, the apparent thermal decomposition activation energies were calculated by the Ozawa and Kissinger methods with a Shimadzu TGA 60 thermogravimetric analysis thermobalance. All the products showed moderate activity against different strains of bacteria and fungi.  相似文献   
102.
BACKGROUND: Division of the sternum is primarily a blind procedure in reoperation and carries an increased risk of injury for major cardiac structures in the presence of adhesions between the posterior table and the heart. METHODS: Two hundred patients were randomly divided into two groups. Cardiopulmonary bypass was established through the femoral artery and vein in group 1 (n = 100) patients before sternal reentry. Carpentier dual-stage femoral venous return cannula was used in all group 1 patients. Cardiopulmonary bypass was performed after sternal reentry in group 2 (n = 100) patients. RESULTS: Six severe cardiac injuries developed in group 2. Cardiopulmonary bypass time was 93 +/- 9 minutes in group 1 and 71 +/- 11 minutes in group 2 (p = 0.011), and the operation time was 155 +/- 23 minutes in group 1 and 185 +/- 32 minutes in group 2 (p = 0.024). Inotropic therapy was required in 52 patients in group 1 and 76 patients in group 2 (p = 0.032). Average chest drainage was 450 +/- 135 mL in group 1 and 850 +/- 250 mL in group 2 (p < 0.001). Average fresh whole blood transfusion was 3.3 +/- 1.2 U in group 1 and 5.8 +/- 0.9 U in group 2 (p = 0.033). Average intensive care unit stay was 2.2 +/- 1.3 days in group 1 and 4.5 +/- 2.3 days in group 2 (p = 0.025). Average hospital stay was 7.3 +/- 2.4 days in group 1 and 9.1 +/- 3.1 days for group 2 (p = 0.011). CONCLUSIONS: Cardiopulmonary bypass by bicaval Carpentier femoral venous cannula before resternotomy not only allows adequate cardiopulmonary bypass flow but also significantly reduces the risk of cardiac injury and catastrophic hemorrhage and allows safe reopening. Although this procedure increases cardiopulmonary bypass time, the operation time, bleeding, and blood transfusion requirement are significantly reduced.  相似文献   
103.
OBJECTIVE: We wanted to compare the efficacies of 95% ethanol and 20% hypertonic saline (HS) sclerotherapies that were performed in a single session under CT guidance for the management of simple renal cysts. MATERIALS AND METHODS: A prospective series of 74 consecutive patients (average age: 57.6 +/- 8.1 years) with simple renal cysts were enrolled in this study. They were randomized into two groups and 95% ethanol or 20% HS, respectively, corresponding to 25% of the aspiration volume, was injected. Treatment success was determined six months later with follow-up clinical evaluation and performing ultrasonography. RESULTS: The sclerotherapy was accepted as technically successful without major complications in all except two patients who were excluded because of a communication between the simple renal cyst and the pelvicalyceal collecting system. Thirty-six patients in the ethanol group received sclerotherapy with 95% ethanol and 36 patients in the HS group underwent sclerotherapy with 20% HS. The complete regression ratio of the ethanol group was significantly higher (94% versus 72%, respectively) than that of the HS group. There was one patient with partial regression in each group. The failure ratio of the ethanol group was significantly lower (3% versus 25%, respectively) than that of the HS group. CONCLUSION: Ethanol sclerotherapy under CT guidance is a successful and safe procedure and it can be used for the treatment of simple renal cysts. Sclerotherapy with 95% ethanol is more effective than 20% HS sclerotherapy. Sclerotherapy with HS may be an option for patients preferring to undergo a less painful treatment procedure.  相似文献   
104.
Anovaginal fistulae (AVF) are frequently seen in patients with inflammatory bowel disease, especially in Crohn disease with active colonic inflammation. Herein, we report a 21-year-old woman with Crohn disease suffering from vaginal discharge and anal pain. Although clinical presentation was very suggestive of AVF, physical examination and colonoscopy were inconclusive. We used an alternative technique and performed magnetic resonance fistulography by applying rectal contrast for the demonstration of AVF.  相似文献   
105.
OBJECTIVE: To assess impact of scanning direction on heart rates at certain levels of heart in electrocardiogram-gated 16-multidetector computed tomography (MDCT) detection of coronary artery bypass grafts and native coronary arteries. METHODS: Ninety patients with 219 grafts were studied by 16-MDCT. Forty-five patients were scanned craniocaudally. The remaining 45 patients were scanned caudocranially. Heart rates at each level were noted and compared between the 2 groups. RESULTS: The difference between mean heart rates of craniocaudal and caudocranial groups was found to be statistically significant at midcardiac, internal mammary artery origin, and cardiac base levels (P < 0.05). For the remaining levels, there was no statistically significant difference in mean heart rates. CONCLUSIONS: Performing electrocardiogram-gated 16-MDCT angiography for the evaluation of coronary arteries and bypass grafts in caudocranial direction provides lower heart rate at midcardiac and cardiac base levels of the heart, which are more prone to motion artifacts.  相似文献   
106.
Objectives: To ascertain the beneficial effects of infliximab an inhibitor of tumor necrosis factor alpha (TNF-α) on the development of NEC in an experimental NEC rat model. Material and Methods: Thirty newborn Sprague-Dawley rats were randomly divided into three groups as NEC, NEC+ infliximab, and control. NEC was induced by enteral formula feeding, exposure to hypoxia-hyperoxia and cold stress. Pups in the NEC+ infliximab group were administered infliximab at a dose of 10 mg/kg daily by intraperitoneal route from the first day until the end of the study. All pups were sacrificed on the 5th day. Proximal colon and ileum were excised for histopathologic, immunohistochemical (TUNEL and caspase-3), and biochemical evaluation, including, total antioxidant status (TAS), total oxidant status (TOS), malonaldehyde (MDA), and myeloperoxdase (MPO) and TNF-α activities. Results: We observed better clinical sickness scores, weight gain, and survival rate in the NEC+ infliximab group compared to the NEC group (p < .05). Histopathological and apoptosis examination (TUNEL and immunohistochemical evaluation for caspase-3) revealed lower damage in the NEC+ infliximab group compared to the damage in the NEC group (p < .01). Tissue MDA, MPO, TNF-α levels, and TOS were significantly decreased in the NEC+infliximab group, whereas TAS was significantly increased in the NEC + infliximab group (p < .01). Conclusion: TNF-α blockade with infliximab efficiently reduced the intestinal injury and preserve the intestinal tissues from severe intestinal damage by its complex mechanisms on NEC. Therefore, it may be an alternative option for the treatment of NEC.  相似文献   
107.
Arsenic causes lipid peroxidation leading to alterations in antioxidant status in organisms. In this study, the reproductive effects of chronic exposure to arsenic and the protective effects of polydatin (PD) were evaluated in 35 Wistar male rats, which were divided equally into five groups. The control group received a normal diet and tap water, arsenic (100 mg l?1, approximately 1/50 of oral LD50) was given via drinking water to experimental groups except control group, and PD was orally given to the other groups at dose of 50, 100 and 200 mg kg?1 for 60 days. Arsenic administration decreased sperm motility, glutathione level, superoxide dismutase and catalase activities in testicular tissue of rats. In contrast, malondialdehyde level and DNA damage were found to be high levels in arsenic‐treated group. Histopathologically, it was observed that decreased sperm concentration and degeneration of Sertoli cells in testicular tissue. PD administration, partially 200 mg kg?1, reversed arsenic‐induced lipid peroxidation, DNA damage, antioxidant enzyme activity and cell integrity in testis of rats. These results demonstrate that PD decreases arsenic‐induced lipid peroxidation, enhances the antioxidant defence mechanism and regenerates tissue damage in testis of rats.  相似文献   
108.
Brown tumors are the end stage of primary or secondary hyperparathyroidism. Such lesions are rare because hyperparathyroidism is now usually diagnosed and treated before they develop. Skeletal bone is most frequently involved, whereas sellar-parasellar involvement is extremely rare. We report a patient with a brown tumor involving the sellar-parasellar region associated with primary hyperparathyroidism. The patient's clinical history and biochemical and radiological tests were used for the diagnosis. Excision of the sellar-parasellar mass enabled histopathological confirmation and surgical decompression of neural structures. After the transsphenoidal surgery, excision of a parathyroid adenoma normalized the patient's metabolic status. Brown tumors are rarely associated with complications but occasionally may compress neural structures such as the optic nerve as they enlarge.  相似文献   
109.
Various general and regional anesthesia methods are used successfully in living-donor kidney transplantation. This study compared kidney graft function after general versus combined spinal-epidural anesthesia for donor nephrectomy. The study groups included recipients who received grafts from donors who had undergone nephrectomy under general anesthesia (GA group; n=10), and recipients who received grafts from donors who had combined spinal-epidural anesthesia (CSE group, n=10). Standard continuous epidural anesthesia was administered during all transplantations. Graft function was assessed using scintigraphy and Doppler ultrasonography on days 3 and 7. Urine levels of microalbumin, creatinine, and creatinine clearance rate were measured/calculated in 24-hour urine samples collected on postoperative days 3 and 7. There were no differences on either day 3 or day 7 with respect to glomerular filtration rate, microalbuminuria, or creatinine clearance rate (P >.05 for all). There were also no differences between the groups with respect to other scintigraphic findings on day 3 or day 7 (P >.05 for all). Ultrasonography on day 7 showed significantly higher mean peak systolic flow in the main renal artery in the CSE group than in the GA group (P=.035). The results suggest that GA and CSE for donor nephrectomy have similar effects on kidney graft function in recipients.  相似文献   
110.
Summary.  Objective: To present a 42-year-old female patient with multifocal cavernous hemangioma of the skull associated with nasal osteoma.  Design: A case report.  Intervention methods: X-rays, computerized tomography, magnetic resonance imaging, and histopathology were used to achieve the diagnosis of this rare entity. The multiple cavernous hemangiomas were resected en-bloc and a curettage biopsy was obtained from the nasal osteoma.  Results: The patient healed well after the operation. No recurrences of the cavernous hemangiomas were observed after one-year follow-up.  Conclusion: Multifocal cavernous hemangiomas are rare benign lesions of the calvarium, arising from the intrinsic vasculature of the bone. Although they are benign, radiological findings are not always characteristic and their multiple presentation may easily make surgeons consider the other malignancies of the skull in the differential diagnosis. Histopathologic confirmation of the tumor is the definitive method for diagnosis. The treatment of choice is early en bloc resection of the tumour where it is possible. Published online April 28, 2003  Correspondence: Kayhan Kuzeylı˙, M.D., Karadeniz Teknik U¨niversitesi, Farabi Hastanesi N?roşirurji AbD, 61080 Trabzon, Türkiye.  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