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   9566篇
  免费   514篇
  国内免费   73篇
耳鼻咽喉   182篇
儿科学   261篇
妇产科学   151篇
基础医学   1277篇
口腔科学   157篇
临床医学   638篇
内科学   2915篇
皮肤病学   239篇
神经病学   596篇
特种医学   207篇
外科学   1349篇
综合类   30篇
一般理论   1篇
预防医学   312篇
眼科学   64篇
药学   682篇
中国医学   43篇
肿瘤学   1049篇
  2023年   64篇
  2022年   111篇
  2021年   195篇
  2020年   131篇
  2019年   189篇
  2018年   170篇
  2017年   151篇
  2016年   201篇
  2015年   215篇
  2014年   274篇
  2013年   310篇
  2012年   568篇
  2011年   604篇
  2010年   339篇
  2009年   318篇
  2008年   470篇
  2007年   531篇
  2006年   494篇
  2005年   562篇
  2004年   557篇
  2003年   505篇
  2002年   508篇
  2001年   197篇
  2000年   228篇
  1999年   243篇
  1998年   105篇
  1997年   97篇
  1996年   100篇
  1995年   82篇
  1994年   67篇
  1993年   72篇
  1992年   132篇
  1991年   132篇
  1990年   127篇
  1989年   145篇
  1988年   124篇
  1987年   99篇
  1986年   102篇
  1985年   106篇
  1984年   60篇
  1983年   49篇
  1982年   27篇
  1979年   46篇
  1978年   27篇
  1975年   27篇
  1974年   27篇
  1973年   27篇
  1970年   27篇
  1969年   24篇
  1968年   24篇
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
21.
A rare case of a dissecting aneurysm of the P3 segment of the right posterior cerebral artery is presented that seems to have occurred in association with mild head injury. The patient was treated surgically because of repeated intramural hemorrhage and enlargement of the aneurysm. Proximal ligation produced thrombosis of the aneurysm without resulting in infarction in the region of the posterior cerebral artery. The mechanisms of the dissection, diagnosis, and treatment are briefly discussed.  相似文献   
22.
Minocycline is an antibiotic now recognized to have antiapoptotic and antiinflammatory properties. Because of these properties, minocycline may be of benefit in reducing neuronal apoptosis from ischemia and subsequent postischemic inflammation if administered soon after a stroke. We now explore the feasibility of using (99m)Tc-annexin V, an in vivo marker of apoptosis, with SPECT to monitor the antiapoptotic effects of minocycline therapy. METHODS: CB6/F1 adult male mice underwent unilateral distal middle cerebral artery occlusion (dMCA) occlusion and were imaged and sacrificed at 1, 3, 7, or 30 d after injury. Animals were given minocycline (or vehicle) 30 min and 12 h after dMCA occlusion and then given 22.5 mg/kg twice daily for up to 7 d. Before imaging, behavioral tests were performed to evaluate the neurologic function. After imaging, brains were collected for histology and assessed for the degree of apoptosis and microglial activation. RESULTS: (99m)Tc-Annexin V uptake in injured hemispheres was significantly decreased 2- to 3-fold by minocycline at all time points. Minocyline reduced infarct size as seen histologically and improved behavioral indices as late as 30 d. Infarct volume as seen histologically correlated with radiolabeled annexin V uptake seen by SPECT. In situ fluorescent microscopy demonstrated that annexin V bound primarily to neurons at 1 and 3 d, with a shift toward microglia by 7 and 30 d. CONCLUSION: We found that minocycline significantly reduces neuronal apoptosis and infarct size and improves neurologic outcome in mice after acute focal cortical ischemia.  相似文献   
23.
OBJECTIVE: Our treatment strategy for pulmonary atresia with ventricular septal defect (VSD) and major aortopulmonary collateral arteries is a staged repair that comprises the first complete unifocalization (UF) with 'unification' of intrapulmonary arteries and then the definitive repair. The purpose of this study is to evaluate the outcome of our staged repair strategy with complete UF and to determine the results of our current management strategy. METHODS: From 1982 to 2004, 113 consecutive patients were treated with staged repair at our institute. We evaluated the risk of definitive repair failure or death in the 3 years after definitive repair using logistic regression. Furthermore, we compared the early group (patients who underwent UF before December 1995) and the late group (patients who underwent UF after January 1996). RESULTS: The mean follow-up interval was 8.8 years (0.8 months to 23.3 years), and Kaplan-Meier-estimated overall survival rates after first UF were 80.9, 73.8, and 69.9% at 5, 10, and 15 years, respectively. Survival in patients with an absent central pulmonary artery (PA) was significantly lower than in those with a central PA (p<0.05), and the factor that was significantly associated with definitive repair failure or death in the 3 years after definitive repair was central PA morphology (p<0.05). Higher mean PA pressure after UF was detected in patients with hypoplastic central PA, compared with those without hypoplastic PA (30.9 mmHg vs 23.3 mmHg, p<0.05). In the late group, age (in years) at first UF (3.9 vs 8.4, p<0.01), second UF (4.3 vs 9.2, p<0.01), and definitive repair (5.8 vs 9.1, p<0.01) was significantly younger than in early group, and the survival rate after first UF in the late group was 96.2 and 91.3% at 3 and 7 years, respectively. Systolic right ventricular pressure and the pressure ratio between the right and the left ventricles after definitive repair in the late group were significantly lower than in the early group (53.6 mmHg vs 75.0 mmHg, p<0.01; 61.7% vs 75.9%, p<0.05). CONCLUSIONS: Hypoplastic central PA was a significant risk factor in this disease. The overall survival was improved by our current management strategy. Improved RV pressure after definitive repair appears to affect the long-term outcome.  相似文献   
24.
Aneurysm of the innominate artery is uncommon compared with other peripheral aneurysms, and holds the potential for rupture, embolization, or thrombosis as well as various complications caused by compression to the adjacent structures. The most effective treatment for this condition is surgical resection, but the earlier reports described high mortality rates. We report the case of an 83-year-old asymptomatic woman with an aneurysm in the innominate artery, which was successfully resected and repaired with the use of modern surgical techniques of hypothermic circulatory arrest and selective cerebral perfusion. Aggressive surgical intervention should be employed despite the fact that a patients is asymptomatic.  相似文献   
25.
We describe a patient with acute lymphoblastic leukemia (ALL) in whom hemopoiesis recovered after an autologous marrow graft purged by in vitro hyperthermia. A 17-year-old woman was diagnosed as having ALL in April 1985. After clinical remission was induced, marrow cells were harvested. The marrow cells were treated with hyperthermia at 42.0 degrees C for 1 h in the presence of alpha-interferon to eliminate residual leukemic cells, and then cryopreserved. In January 1990, during her fourth remission she was treated with busulfan and cyclophosphamide, and then received the thawed autologous marrow. Her hematopoietic recovery was prompt with normal trilineage regeneration without any life-threatening complications. She is in good health without evidence of a leukemic relapse at 6 months after autologous bone marrow transplantation. This case suggests that human multilineage progenitor cells retain self-renewal capacity in vivo even after treatment with heat and alpha-interferon in vitro followed by the freezing and thawing procedures.  相似文献   
26.
The effect of XKJ-001, a crude drug preparation based on Seisho-ekki-to, was investigated on the hematocrit, plasma volume, extracellular and interstitial fluid volumes as well as water excretion in mice. Mice were housed in an animal room maintained at 34 degrees C for 3 d with water and food freely available. While the hematocrit, extracellular and interstitial fluid volumes increased, the plasma volume decreased. These results suggest that the distribution of body water in mice housed at high environmental temperature exhibit the state of water metabolism disorders (Suitai) described in Kampo medicine. After the administration of XKJ-001 (3 g/kg, once a day) for 5 d, mice were housed in an animal room maintained at 34 degrees C for 3 d. The administration of XKJ-001 was allowed to continue on the day 0, day 1 and day 2. XKJ-001 inhibited the increase in hematocrit and the changes in body water distribution of mice induced by high environmental temperature. An effect of XKJ-001 on water excretion in mice was investigated in comparison with hydrochlorothiazide (HTZ). Distilled water (D.W., 100 ml/kg) or bicarbonate saline (B.S., 100 ml/kg) was intraperitoneally injected immediately after the oral administration of XKJ-001 (1.5 g/kg) or HTZ (15 mg/kg). The water excretion was enhanced after 3 h for XKJ-001 and after 6 h for HTZ after the intraperitoneal injection of D.W. As for the intraperitoneal injection of BS, HTZ enhanced the water excretion, however, XKJ-001 exhibited no effect. These results suggest that XKJ-001 has activities on water maldistribution and facilitates the water excretion.  相似文献   
27.
Twelve patients with ureteral tumours with or without ipsilateral renal pelvic neoplasms were retrospectively analysed. Haematuria was the most common symptom. Location of all tumours was preoperatively detected by conventional diagnostic methods, such as intravenous or retrograde pyelography, washing cytology of the upper urinary tract, computed tomography, echogram and abdominal aortography. Cumulative proportion survivals of 1, 3 and 5 years were 81.9%, 68.2% and 45.5%, respectively. Patients with high Karnovsky rating survived longer (p<0.05) than those with low rating. Patients with low-stage tumours (T1, T2) showed longer survival rate (p<0.001) than those with high-stage tumours (T3, T4). Vascular invasion of tumour cells was present in removed specimens in 4 out of 7 patients who died or are alive with cancer, but none in those who survived without disease. Good therapeutic response could not be achieved unless surgery was performed.  相似文献   
28.
Collapsin response mediating protein-2 (CRMP2) has been identified as an intracellular protein mediating Semaphorin3A (Sema3A), a repulsive guidance molecule. In this study, we demonstrate that cyclin-dependent kinase 5 (Cdk5) and glycogen synthase kinase 3beta (GSK3beta) plays a critical role in Sema3A signalling. In In vitro kinase assay, Cdk5 phosphorylated CRMP2 at Ser522, while GSK3beta did not induce any phosphorylation of CRMP2. Phosphorylation by GSK3beta was exclusively observed in Cdk5-phosphorylated CRMP2, but barely in CRMP2T509A. These results indicate that Cdk5 primarily phosphorylates CRMP2 at Ser522 and GSK3beta secondarily phosphorylates at Thr509. The dual-phosphorylated CRMP2, but not non-phosphorylated or single-phosphorylated CRMP2, is recognized with the antibody 3F4, which is highly reactive with the neurofibrillary tangles of Alzheimer's disease. 3F4 recognized the CRMP2 in the wild-type but not cdk5-/- mouse embryonic brain lysates. The phosphorylation of CRMP2 at Ser522 caused reduction of its affinity to tubulin. In dorsal root ganglion neurones, Sema3A stimulation enhanced the levels of the phosphorylated form of CRMP2 detected by 3F4. Over-expression of CRMP2 mutant substituting either Ser522 or Thr509 to Ala attenuates Sema3A-induced growth cone collapse response. These results suggest that the sequential phosphorylation of CRMP is an important process of Sema3A signalling and the same mechanism may have some relevance to the pathological aggregation of the microtubule-associated proteins.  相似文献   
29.
The effects of 1-antitrypsin ( 1,-AT), 1,-acid glycoprotein ( 1AGP), and haptoglobin (Hp), the main constituents of-globulin and which belong to acute phase proteins, on NK activity were examined using K562 cells as the NK target cells. Among the three proteins, 1,-AT and 1AGP had inhibitory effects on NK activity for fast target K562 cells. The,-AT preparations having the same protein concentration and a different trypsin inhibitory capacity (TIC) had an equal effect. Although 1AT and 1,-AGP equally reduced the NK activity, the mechanism involved in the reduction differed, in that the effect of 1,-AT directed toward NK cells reduced their binding capacity with the target cells, 1,-AGP probably interacts with a cytotoxic factor secreted from NK cells following effector-target interaction. These studies suggest that each of the acute-phase proteins, which increase following inflammation, inhibits NK cell function by two distinct mechanisms.  相似文献   
30.
In a retrospective study, antibody to hepatitis C virus (anti-HCV antibody) was measured in 80 patients with acute viral hepatitis (type A, 18; type B, 21; type non-A,non-B, 41). Anti-HCV antibody was found in 12 of 20 patients (60%) with non-A,non-B post-transfusion hepatitis (NANB-PTH) and in 9 of 21 patients (43%) with sporadic NANB hepatitis (NANB-SPO). Patients with acute hepatitis type A or type B did not have anti-HCV antibody. The number of patients who developed chronic hepatitis was greater in the group with anti-HCV antibody than in the anti-HCV negative group in both NANB-PTH and NANB-SPO. The difference was significant in those with NANB-PTH (P less than 0.05). To investigate the relationship between the long-term prognosis of NANB-PTH and the course of anti-HCV, we studied anti-HCV antibody in 12 patients who developed chronic type C hepatitis (C-CH) after PTH and followed them for more than 5 years after the development of PTH. One year after the development of PTH, all 12 had anti-HCV antibody. Five lost anti-HCV antibody (group 1) while 7 remained positive (group 2) at the final examination. Four of the 5 patients in group 1 had normal serum transaminases; however, abnormal transaminase persisted in all 7 patients in group 2 until the end of follow-up (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)  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