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   5346篇
  免费   280篇
  国内免费   64篇
耳鼻咽喉   52篇
儿科学   44篇
妇产科学   30篇
基础医学   531篇
口腔科学   59篇
临床医学   324篇
内科学   1620篇
皮肤病学   73篇
神经病学   377篇
特种医学   216篇
外科学   952篇
综合类   9篇
预防医学   110篇
眼科学   92篇
药学   314篇
中国医学   19篇
肿瘤学   868篇
  2023年   40篇
  2022年   65篇
  2021年   138篇
  2020年   74篇
  2019年   128篇
  2018年   137篇
  2017年   134篇
  2016年   143篇
  2015年   148篇
  2014年   197篇
  2013年   198篇
  2012年   384篇
  2011年   408篇
  2010年   277篇
  2009年   194篇
  2008年   347篇
  2007年   331篇
  2006年   353篇
  2005年   364篇
  2004年   315篇
  2003年   329篇
  2002年   353篇
  2001年   60篇
  2000年   59篇
  1999年   50篇
  1998年   76篇
  1997年   52篇
  1996年   49篇
  1995年   54篇
  1994年   39篇
  1993年   34篇
  1992年   23篇
  1991年   14篇
  1990年   15篇
  1989年   16篇
  1988年   17篇
  1987年   6篇
  1986年   5篇
  1985年   7篇
  1984年   6篇
  1983年   5篇
  1982年   6篇
  1981年   9篇
  1980年   10篇
  1979年   4篇
  1978年   3篇
  1977年   3篇
  1966年   2篇
  1962年   1篇
  1957年   1篇
排序方式: 共有5690条查询结果,搜索用时 15 毫秒
31.
32.
A 14-year-old girl with rapidly progressive glomerulonephritis was transferred to our hospital because of acute renal failure. A diagnosis of Wegener granulomatosis was made according to the symptom triad of a renal biopsy demonstrating crescentic glomerulonephritis, severe sinusitis, and serological findings of raised proteinase 3 anti-neutrophil cytoplasmic antibody level. In spite of combination therapy with methylprednisolone, cyclophosphamide, and plasma exchange, her renal function gradually deteriorated. Thereafter, she suffered a severe headache and generalized seizures. Brain computed tomography (CT) scan revealed bilateral low-density areas in the parieto-occipital lobes. Magnetic resonance imaging (MRI) disclosed a high-intensity area on T2-weighted images and a low-signal intensity area on T1-weighted images in the same lesion. Follow-up brain CT scan 3 weeks and MRI 2 months after the first studies showed complete resolution of the abnormal lesions, which indicated reversible posterior leukoencephalopathy syndrome. In addition to renal failure, hypertension, and cyclophoshamide, the primary disease may have played a role in the development of this uncommon syndrome in our patient.  相似文献   
33.
We investigated whether mesenchymal stem cells (MSCs) in synovial fluid (SF) increased in the knee with degenerated cartilage and osteoarthritis. SF was obtained from the knee joints of 22 patients with anterior cruciate ligament (ACL) injury during ACL reconstruction, and cartilage degeneration was evaluated arthroscopically. SF was also obtained from the knee joints of 6 healthy volunteers, 20 patients with mild osteoarthritis, and 26 patients with severe osteoarthritis, in which the grading was evaluated radiographically. The cell component in the SF was cultured for analyses. Synovium (SYN) and bone marrow (BM) were also harvested during total knee arthroplasties. The MSC number in SF was correlated with the cartilage degeneration score evaluated by arthroscopy. The MSC number in the SF was hardly noticed in normal volunteers, but it increased in accordance with the grading of osteoarthritis. Though no significant differences were observed regarding surface epitopes, or differentiation potentials, the morphology and gene profiles in SF MSCs were more similar to those in SYN MSCs than in BM MSCs. We listed 20 genes which were expressed higher in both SYN MSCs and SF MSCs than in BM MSCs, and 3 genes were confirmed by quantitative RT-PCR. MSCs in SF increased along with degenerated cartilage and osteoarthritis.  相似文献   
34.

Purpose

The purpose of this study was to investigate the relationship between the blood levels of interleukin (IL)-18 measured in the early stage of acute respiratory failure and the prognosis for patient survival.

Methods

The study subjects were 38 patients with acute respiratory failure treated at our institution during the 4-year period from April 2004 to March 2008. The underlying clinical condition was defined as acute respiratory distress syndrome (ARDS; n?=?12) or acute lung injury (ALI; n?=?26). The serum levels of interleukin (IL)-18, IL-12, and tumor necrosis factor (TNF)-α were measured by enzyme-linked immunosorbent assays.

Results

The ARDS group showed significantly higher serum levels of IL-18, IL-12, and TNF-α even at an early stage after disease onset compared with the ALI group. A negative correlation was noted between the PaO2/FIO2 ratio (P/F ratio) and serum IL-18 level. Analysis of all 38 patients with ALI/ARDS revealed a 30-day mortality rate of 7.9?%, 60-day mortality rate of 15.8?%, and 90-day mortality rate of 18.4?%. The early-stage serum levels of IL-18, IL-12, and TNF-α were significantly higher in the non-survivors at 60 and 90?days, but not at 30?days, than in the corresponding survivors.

Conclusion

The present data demonstrate an inverse correlation between serum IL-18 level and the P/F ratio, suggesting the possible involvement of IL-18 in the pathogenesis of respiratory failure in patients with ALI/ARDS. Early-stage serum IL-18, IL-12, and TNF-α levels appear to reflect the >60-day prognosis in patients with ALI/ARDS.  相似文献   
35.
BACKGROUND: Afferent limb syndrome is a relatively rare cause of small bowel obstruction after restorative total proctocolectomy with ileal pouch-anal anastomosis for patients with ulcerative colitis or familial adenomatous polyposis. DISCUSSION: This report describes three patients who developed recurrent small bowel obstruction after ileal pouch-anal anastomosis. The bowel obstruction was caused by torsion of the ileum at the inlet of the ileal J-pouch, which was thought to be a variant of afferent limb syndrome. This variant of afferent limb syndrome is characterized by a flexible afferent limb of the pelvic pouch due to the lack adhesion of the ileum in the abdominal cavity. Preoperative diagnosis required multiple series of contrast small bowel enemas. Strictureplasty and ileopexy effectively resolved the recurrent bowel obstruction caused by this variant of afferent limb syndrome.  相似文献   
36.
Objective: Paraplegia remains a serious complication of aortic operations. The production of free radicals during reperfusion after transient ischemia is believed to induce secondary spinal neuronal injury, resulting in paraplegia. The aim of the present study was to clarify the protective effect and method of administration of antioxidants on the neurological and histological outcome in the animal model for reperfusion injury after transient spinal cord ischemia. Methods: New Zealand white rabbits underwent surgical exposure of the abdominal aorta that was clamped for 15 minutes to achieve spinal cord ischemia. Group A animals received two 10 mg/kg doses of 3-methyl-l-phenyl-2-pyrazolin-5-one (MCI-186) at the time of release of the aortic clamp and 30 minutes later. In group B, MCI-186, 5 mg/kg, was given three times, at the time of aorta clamp release, 30 minutes and 12 hours later. In group C (control group), one dose of vehicle was administered. Neurological status was assessed using modified Tarlov’s score until 168 hours after operation. Spinal cord sections were examined microscopically to determine the extent of ischemic neuronal damage. Results: Groups A and B animals had better neurological function than group C (p(0.001). In contrast, group C animals exhibited paraplegia or paraparesis with marked neuronal necrosis. The number of surviving neurons within examined sections of the spinal cord was significantly greater in group B than in group C (p(0.001). Conclusion: In a 15-minute ischemia-reperfusion model using rabbits, systemic repetitious administration of MCI-186, a free radical scavenger, was found to have a protective effect on the spinal cord neurons both neurologically and histologically. We postulate that the drug minimizes the delayed neuronal cell death for reperfusion injury after transient ischemia by reducing the free radical molecules. Moreover, it was thought that we could protect delayed neuronal cell death more effectively by administering MCI-18612 hours later.  相似文献   
37.
Background: Low-flow sevoflurane anesthesia is associated with increasing circuit concentrations of compound A, which is nephrotoxic in rats, but the effect of compound A and low-flow sevoflurane anesthesia on renal function in humans is unclear. The authors compared the effects of high- and low-flow sevoflurane and isoflurane anesthesia on renal function and on several possible markers of nephrotoxicity in humans.

Methods: Forty-two patients without preexisting renal disease underwent either low-flow isoflurane (1 l/min, n = 14), low-flow sevoflurane (1 l/min, n = 14), or high-flow sevoflurane (6 l/min, n = 14) anesthesia for body-surface-area surgery scheduled to last at least 4 h. Twenty-four-hour urinary excretion of N-acetyl-[small beta, Greek]-glucosaminidase (NAG), [small beta, Greek]2-microglobulin, protein, glucose, blood urea nitrogen (BUN), and serum creatinine concentrations were measured before and after anesthesia.

Results: There were no differences in blood urea nitrogen, creatinine, and creatinine clearance among the three groups after anesthesia. Increased urinary N-acetyl-[small beta, Greek]-glucosaminidase excretions were seen in the low-flow and high-flow sevoflurane groups, but not in the low-flow isoflurane group (P < 0.01). Ten patients in the low-flow sevoflurane group had 24-h urinary excretion of protein that exceeded the normal ranges after anesthesia, but only one patient in the isoflurane and none in the high-flow sevoflurane groups had this.  相似文献   

38.
Gelatin sponge (GS) is one of the most widely used embolic agents in interventional procedures. There are four commercially available GS products in Japan; however, the endovascular use of Gelfoam and Spongel is off-label, and Gelpart can only be used for hepatic artery embolization and Serescue can only be used for hemostasis of arterial bleeding. GS has been used for a variety of clinical indications, mainly tumor embolization and stopping massive arterial bleeding. The optimal size and preparation procedure of GS particles differs slightly for each clinical indication. In addition, there is a risk of ischemic and/or infectious complications associated with GS embolization in various situations. Therefore, radiologists should be familiar with not only the preparation and handling of GS particles, but also the disadvantages and potential risks, in order to perform GS embolization safely and effectively.  相似文献   
39.
Between November 1994 and January 1997, 42 cases of cyanotic congenital cardiac defects underwent definitive surgery at Matsudo Municipal Hospital. We evaluated 30 cases, each weighing from 7 to 20 kg. The procedures were performed at the age of 9 months to 6 years (mean age—2.4 years). The body weights were 7.7 to 20 kg (mean weight—11.4 kg). The preoperative diagnoses were Tetralogy of Fallot (TOF) in 19 cases, Fontan candidates in 6 and the others in 5. We classified them into 3 groups; Group Abstract—15 cases were completed with non-blood transfusion, Group B—8 cases used only plasma protein fraction and Group C—7 cases used blood transfusion. Cardiopulmonary bypass (CPB) system is a semi-closed circuit and priming volume is 400 to 600 ml. There is no difference among the 3 groups in operative age, body weight, opeartion time, CPB time, aortic cross clamp time, bleeding and postoperative state. The same results were obtained in minimum base excess and urine output during CPB and the changes of hematocrit and total protein. In Groups A and B, CPB blood was retruned to the patient as soon as possible after CPB was weaned, but in Group C, blood transfusion was performed without the return of CPB blood. In all groups, hemodynamics were stable. Retrospectively, it is thought that blood transfusion was not necessary in Group C and the use of the plamsa protein fraction was not needed in Group B. In conclusion, the open heart surgery can be performed safely without blood transfusion for cyanotic congenital cardiac defects.  相似文献   
40.
Nakao K  Kubota S  Doi H  Eguchi T  Oka M  Fujisawa T  Nishida T  Takigawa M 《BONE》2005,36(5):884-892
It is known that expression of the macrophage colony-stimulating factor (M-CSF) gene is induced in articular chondrocytes upon inflammation. However, the functional role of M-CSF in cartilage has been unclear. In this study, we describe possible roles of M-CSF in the protection and maintenance of the articular cartilage based on the results of experiments using human chondrocytic cells and rat primary chondrocytes. Connective tissue growth factor (CTGF/CCN2) is known to be a potent molecule to regenerate damaged cartilage by promoting the growth and differentiation of articular chondrocytes. Here, we uncovered the fact that M-CSF induced the mRNA expression of the ctgf/ccn2 gene in those cells. Enhanced production of CTGF/CCN2 protein by M-CSF was also confirmed. Furthermore, M-CSF could autoactivate the m-csf gene, forming a positive feed-back network to amplify and prolong the observed effects. Finally, promotion of proteoglycan synthesis was observed by the addition of M-CSF. These findings taken together indicate novel roles of M-CSF in articular cartilage metabolism in collaboration with CTGF/CCN2, particularly during an inflammatory response. Such roles of M-CSF were further supported by the distribution of M-CSF producing chondrocytes in experimentally induced rat osteoarthritis cartilage in vivo.  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