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   4746篇
  免费   215篇
  国内免费   60篇
耳鼻咽喉   25篇
儿科学   52篇
妇产科学   34篇
基础医学   565篇
口腔科学   66篇
临床医学   251篇
内科学   1232篇
皮肤病学   39篇
神经病学   413篇
特种医学   335篇
外科学   924篇
综合类   34篇
预防医学   165篇
眼科学   30篇
药学   286篇
中国医学   6篇
肿瘤学   564篇
  2023年   39篇
  2022年   66篇
  2021年   96篇
  2020年   50篇
  2019年   83篇
  2018年   90篇
  2017年   96篇
  2016年   99篇
  2015年   101篇
  2014年   145篇
  2013年   142篇
  2012年   271篇
  2011年   289篇
  2010年   194篇
  2009年   152篇
  2008年   279篇
  2007年   316篇
  2006年   322篇
  2005年   321篇
  2004年   305篇
  2003年   300篇
  2002年   327篇
  2001年   71篇
  2000年   64篇
  1999年   69篇
  1998年   57篇
  1997年   59篇
  1996年   59篇
  1995年   57篇
  1994年   51篇
  1993年   66篇
  1992年   35篇
  1991年   46篇
  1990年   29篇
  1989年   25篇
  1988年   21篇
  1987年   21篇
  1986年   13篇
  1985年   16篇
  1984年   33篇
  1983年   18篇
  1982年   14篇
  1981年   25篇
  1980年   16篇
  1979年   11篇
  1978年   8篇
  1977年   9篇
  1974年   8篇
  1973年   5篇
  1968年   5篇
排序方式: 共有5021条查询结果,搜索用时 15 毫秒
51.
Our purpose is to evaluate the diagnostic accuracy of apparent diffusion coefficient (ADC) measurement in differentiating malignant from benign uterine endometrial cavity lesions. We retrospectively evaluated 25 uterine endometrial cavity lesions in 25 female patients: endometrial carcinoma (n = 11), carcinosarcoma (n = 2), submucosal leiomyoma (n = 8), and endometrial polyp (n = 4). Diffusion-weighted images were performed at 1.5 T with b factors of 0–1,000/mm2. The region of interest was defined within the tumor on T2-weighted EPI image and then manually copied to an ADC map. Thereby, the ADC value was obtained. We compared ADC values between malignant and benign lesions using Student’s t-test. The mean and standard deviation of ADC values (×10−3 mm2/s) were as follows: endometrial carcinoma, 0.98±0.21; carcinosarcoma, 0.97±0.02; submucosal leiomyoma, 1.37±0.28; and endometrial polyp, 1.58±0.45. The ADC values differed significantly between malignant (0.98±0.19) and benign lesions (1.44±0.34) (P < 0.01). We defined malignant tumors as cases with an ADC value less than 1.15 × 10−3 mm2/s for obtaining the highest accuracy. Sensitivity, specificity, and accuracy were 84.6%, 100%, and 92%, respectively. ADC measurement can provide useful information in differentiating malignant from benign uterine endometrial cavity lesions.  相似文献   
52.
We describe a patient who survived for a prolonged period after repeated resections of pulmonary metastases from gastric cancer. A 59-year-old man underwent a distal gastrectomy for gastric cancer. A right middle lobectomy and a left lower lobectomy were performed for metastases from gastric cancer at 34 months and 82 months after the initial gastric resection, respectively. The patient died of cerebral infarction 65 months after the first lung resection, with no further relapse. To our knowledge, long-term survival after resection of pulmonary metastases from gastric cancer has only been reported in 3 patients previously. We herein review the literature and discuss the role of surgery in such patients.  相似文献   
53.
We experienced the anesthetic management using high-dose dexmedetomidine for microlaryngeal surgery maintaining spontaneous breathing. The anesthesia was maintained with dexmedetomidine infusion (initial dose 6 microg x kg(-1) x hr(-1) over 10 min followed by continuous infusion of 0.5 microg x kg(-1) x hr(-1)), intermittent small doses of fentanyl and topical application of lidocaine on the tongue, pharynx and larynx. The infusion of dexmedetomidine was increased over 30 min to 3 microg x kg(-1) x hr(-1) to reach the adequate sedation level and maintained at this rate for a further 15 min during the operation. During the whole perioperative period, there was no respiratory depression as measured by arterial blood gas analysis that recorded normal PaCO2 in the patient breathing supplemental oxygen. Hypotension (systemic arterial blood pressure less than 100 mmHg) occurred twice during dexmedetomidine administration, but was normolized by ephedrine administration. The preservation of respiratory drive offers the possibility that this anesthetic technique may be another method for providing anesthesia for the patient with a difficult airway. Moreover, there is one consensus on the importance of the basic principle that adequate topical or intravenous anesthesia is also essential during high-dose dexmedetomidine infusion.  相似文献   
54.
Adipose tissue-derived stem cells (ASCs) are expected to have clinical applications as well as other stem cells, because ASCs can be obtained safely from adult donors and used in autologous therapies without concern about rejection and the need for immunosuppression. However, the use of gene transfer with Sendai virus (SeV) vectors, which can efficiently introduce foreign genes without toxicity into several cells, with ASCs has not yet been investigated. This study documents on the use of SeV vectors for gene transfer to ASCs. The dose-dependent GFP expression of ASCs transfected with SeV vectors after 48 h of culture at 37 degrees C was first evaluated. Next, the cellular toxicity of ASCs transfected with SeV vectors was verified. In addition, SeV vectors were compared with adenovirus (AdV) vectors. Finally, the time-dependent GFP expression of ASCs transfected with SeV vectors was evaluated. The results showed that transfection of ASCs with SeV vectors results in more efficient expression of transgene (GFP expression) in the ASCs than with AdV vectors after 48 h of culture at 37 degrees C. Moreover, while the transfection of ASCs with AdV vectors at high MOIs was cytotoxic (a lot of transfected cells died) that of ASCs with SeV vectors at high MOIs was not necessarily cytotoxic. In addition, the preservation of multilineage ASCs transfected with SeV was observed. In conclusion, this is the first report describing the successful use of SeV-mediated gene transfer in ASCs, and the results indicate that SeV may thus provide advantages with respect to safety issues in gene therapy.  相似文献   
55.
Nagase K  Iida H  Dohi S 《Anesthesia and analgesia》2002,94(4):954-8, table of contents
Although it has been reported that ketamine attenuates hypercapnia-induced cerebral vasodilation, the mechanism remains unknown. Because nitric oxide is involved in cerebral CO2 reactivity, we studied the effects of L-arginine and nitroglycerin on ketamine-mediated attenuation of vascular responses to hypercapnia. Under pentobarbital anesthesia, 16 rabbits underwent closed cranial window preparation. Hypercapnic challenges were repeated after IV saline, ketamine (10 mg/kg, followed by 20 mg x kg(-1) x h(-1)), or ketamine plus either L-arginine (150 mg/kg, followed by 100 mg x kg(-1) x h(-1); n = 8) or nitroglycerin (5 microg x kg(-1) x min(-1) infusion; n = 8). Ketamine reduced hypercapnia-induced cerebral vasodilation (1.27%/mm Hg +/- 0.45%/mm Hg [saline] versus 0.82%/mm Hg +/- 0.53%/mm Hg [ketamine]: P < 0.05), but L-arginine restored reactivity (1.28%/mm Hg +/- 0.73%/mm Hg: P < 0.05 versus ketamine), as did nitroglycerin (1.14%/mm Hg +/- 0.73%/mm Hg [saline] versus 0.56%/mm Hg +/- 0.63%/mm Hg [ketamine]: P < 0.05, and 1.15%/mm Hg +/- 0.74%/mm Hg [ketamine plus nitroglycerin]: P < 0.05 versus ketamine). This indicates that ketamine attenuates cerebral CO2 reactivity, at least in part, via suppression of nitric oxide-cyclic guanosine monophosphate mechanisms in the cerebral vasculature. IMPLICATIONS: The attenuation of cerebral vasodilation to hypercapnia seen under ketamine anesthesia is reversed by L-arginine or nitroglycerin infusion.  相似文献   
56.
AIM:To analyze the relationship between sperm mitochondrial membrane potential and sperm motility parameters by means of a computer-assisted sperm analyzer (CASA) and in-vitro fertilization rate(%FR). METHODS: Semen samples were obtained from 26 men undergoing in vitro fertilization-embryo transfer (IVF-ET). Informed consent was obtained from all men prior to the study. Samples were prepared using wash and swim-up method in HEPES-HTF medium. The sperm motility (%MOT), progressive motility (%PMOT), average path velocity (VAP) microm/s), straight line velocity (VSL) (micro m/s), curvilinear velocity (VCL) (microm/s) and %hyperactivated sperm (%HA), and the %FR were assessed. The samples were incubated in the presence of 2.0 mciromol/L of 5,5',6,6'-tetra-chloro-1,1',3,3'-tetraethylbenzimidazolyl-carbocyanine iodide (JC-1) for 30 min at 37 degrees C in air and washed in PBS before flow cytometry (FACSCalibur: Becton Dickinson) analysis. The mitochondrial probe JC-1 was used to identify the mitochondrial membrane potential. The sperm was divided into three populations according to the fluorescence pattern as follows: the high mitochondrial membrane potential group (n=8), the moderate group (n=5), and the low group (n=13). Statistical analysis was performed using unpaired t-test. RESULTS:Significant differences were found between the high and the low groups in %MOT (91.1+/-8.5 vs 63.0+/-32.7, mean+/-SD), VAP (73.0+/-14.2 vs 52.1+/-12.5), VCL (127.0+/-28.1 vs 87.0+/-22.6), %HA (27.3+/-23.6 vs 7.2+/-9.0) and %FR [73.2 (48/56) vs 59.0 (69/117)]. No significant differences were found in other CASA parameters. CONCLUSION: When the sperm mitochondrial membrane potential increases, sperm motility parameters and fertility potential will also increase. The JC-1 dye method is useful to predict sperm fertility potential.  相似文献   
57.
BACKGROUND: The efficacy of transarterial embolization (TAE) for severe blunt hepatic injury has been reported. We performed a prospective study evaluating the efficacy and the limitation of TAE from January 1996 to December 2000. METHODS: All patients with blunt abdominal injury who could be stabilized by fluid resuscitation underwent computed tomographic (CT) scan examinations. Patients with CT scan evidence of hepatic injury were classified into five grades according to CT scan findings on the basis of the injury scale of the American Association for the Surgery of Trauma (Mirvis classification). All patients with CT scan grade 3 to 5 injury underwent angiography. When angiography showed extravasation of contrast medium extending from hepatic arterial branches, TAE was performed. RESULTS: Of 612 patients with blunt abdominal trauma, 51 had CT scan grade 3 to 5 injury. Thirty-seven of these patients had a CT scan grade 3 injury and 18 underwent TAE. One of 19 patients who did not undergo TAE developed a delayed hemorrhage on day 6 and required a laparotomy. All 13 patients with a CT scan grade 4 injury had angiographic findings of the extravasation. TAE was successful in 11 patients and unsuccessful in 2. Five patients with a CT scan grade 4 injury required laparotomy. One developed a delayed hemorrhage on day 4. The remaining four patients had a major venous injury (a right lobectomy was performed in two with inferior vena cava injury, and a gauze packing in two with hepatic venous injury). One patient with a CT scan grade 5 injury underwent immediate laparotomy after TAE. Laparotomy revealed inferior vena cava injury and a right lobectomy was performed. Only two patients who underwent a lobectomy died of an uncontrollable hemorrhage. All CT scans of patients with hepatic venous or inferior vena cava injury showed a large low-density area (> or = 10 cm) with involvement of these vessels. The volumes of fluid resuscitation needed from admission until TAE ranged from 2,109 to 2,638 mL/h. CONCLUSION: It was considered that the combination of the presence of a CT scan grade 4 or 5 lesion and the fluid requirements of more than 2,000 mL/h to maintain normotension indicated the absolute necessity of surgery. We felt that these patients were not candidates for TAE, and should undergo immediate laparotomy.  相似文献   
58.
PURPOSE: We retrospectively assessed the surgical outcomes of nephron-sparing surgery (NSS) for patients with renal tumors. PATIENTS AND METHODS: From 1985 to March 2001, a total of 99 NSSs were performed on 94 patients with renal tumors. The patients were divided into three groups. Group I comprised of 22 patients who underwent imperative surgeries for renal cell carcinoma (RCC). The tumors were found in 18 patients bilaterally (including 8 patients with von Hippel-Lindau disease), in 3 with solitary kidney, and in 1 with chronic renal failure. The mean +/- standard deviation of patient age and tumor diameter was 46 +/- 23 years and 36 +/- 23 mm, respectively. Twenty-three in situ NSSs were performed on 18 patients in Group I, and the remaining 4 patients were treated with 3 simultaneous operations for bilateral renal tumors with or without 2 ex vivo surgeries. Group II consisted of 49 patients who had small RCCs with the normal contralateral kidney and underwent NSSs (elective indication). The mean age and tumor diameter was 54 +/- 10 years and 28 +/- 11 mm, respectively. Group III consisted of 23 patients with non-RCC tumor (10 angiomyolipomas, 8 cystic tumors, 2 adenomas, 2 metastatic tumors, and 1 degenerative lesion), all of whom were treated with NSS. The mean age and tumor diameter was 47 +/- 14 years and 41 +/- 29 mm, respectively. RESULTS: In Group I, 3 patients died of cancer including 2 patients who had had multiple lung metastases preoperatively. The five-year tumor specific survival rate was 87.3% with a postoperative follow-up of 49 +/- 36 months. In Group II, there were few peri-operative complications or no local recurrence at follow-up of 52 +/- 38 months. A patient developed lung metastasis, which was removed surgically with no evidence of recurrence at 159 months after NSS. Postoperative renal scintigraphy on 35 patients showed well-preserved renal function of the operated kidney. Improvement in surgical techniques resulted in less-invasive surgery in 22 operations during the last 4 years. The patients of Group III were also operated uneventfully, although 1 experienced postoperative bleeding. In 12 patients with solitary kidney (11 in Group I and 1 in Group III) serum creatinine level increased transiently, decreased to 1.3 times of preoperative values within 3 months, and almost recovered at 1-year follow-up. CONCLUSION: Excellent outcomes in cancer control and preservation of renal function support the validity of nephron-sparing surgery to treat renal tumors. The candidate patients may include those with bilateral kidney tumors, tumor occuring in the solitary kidney or small renal cell carcinomas with the normal contralateral kidney. Earlier detection of small lesions and less invasive surgical techniques will facilitate a wider indication of NSS.  相似文献   
59.
OBJECTIVE: To evaluate the initial results of brachytherapy for prostate cancer with permanent iodine-125 implant in Japan. METHODS: The results obtained with brachytherapy in the initial 100 Japanese patients treated at Nagano Municipal Hospital were reviewed. Patients with a prostate-specific antigen (PSA) level of less than 10 ng/mL and a Gleason's scores of 5, 6, 3 + 4 were classified as having a low risk of recurrence. Patients with a PSA level of 10-20 ng/mL and/or a Gleason's score of 4 + 3 were classified as having an intermediate risk for recurrence. Seventy-eight of the low-risk patients and 19 of the intermediate-risk patients were treated by seed implants alone, or seed implants combined with preceding external radiation, respectively. A total of 53 patients received neoadjuvant hormone therapy. The efficacy and morbidity of brachytherapy were investigated using the serum PSA, International Prostate Symptom Score, quality of life score and uroflowmetry data. RESULTS: The average V100 and D90 obtained by post-implant dosimetry was 94.3 and 113.7%, respectively. Serum PSA decreased gradually after treatment, although it had still not reached a nadir after 1 year. There was little difference of the PSA level between the patients with and without neoadjuvant hormone therapy even at 1 year after seed implantation. There were no PSA biochemical failure or clinical recurrence during the follow-up period. Voiding symptoms worsened until 3 months after treatment, and then gradually improved. Acute urinary retention occurred transiently in one patient (1%). Rectal bleeding and severe diarrhea did not occur. CONCLUSION: Brachytherapy is a feasible and effective option for the treatment of prostate cancer in Japanese men. Brachytherapy may have a different effect in Japanese patients with respect to voiding symptoms. Urinary retention was rare, but voiding symptoms were persistent in Japanese patients. Neoadjuvant hormone therapy deserves investigation to determine whether it can achieve better results, especially in patients with an intermediate risk.  相似文献   
60.
We report a 68-year-old woman who had bilateral renal cell carcinoma (RCC) associated with von Hippel-Lindau (VHL) disease. Surgical resection of a central nervous system hemangioblastoma had been done previously. This time, synchronous bilateral RCCs were found in her kidneys, with metastases to lungs and liver. Right radical nephrectomy was performed to remove the primary tumor in the right kidney. Histopathological examination of the tumor revealed clear cell RCC with a sarcomatoid component. After surgery, transcatheter arterial embolization was performed for the tumor in the left kidney and interferon therapy was commenced. The left renal tumor decreased in size and interferon therapy was effective against the metastatic lung tumors. However, 4 years after resection of the right RCC, the tumor in the left kidney increased progressively in size and partial left nephrectomy was performed. Histopathological examination of the resected tumor also showed clear cell type RCC with a sarcomatoid component. The patient eventually died of her disease at 5 years after resection of the right RCC. RCC associated with VHL is usually of the clear cell type has a relatively good prognosis. Sarcomatoid RCC is rare in VHL patients and, to our knowledge, the present report is the first case of sarcomatoid RCC associated with VHL in the Japanese literature.  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