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   3212篇
  免费   115篇
  国内免费   24篇
耳鼻咽喉   28篇
儿科学   46篇
妇产科学   27篇
基础医学   363篇
口腔科学   94篇
临床医学   217篇
内科学   953篇
皮肤病学   28篇
神经病学   155篇
特种医学   112篇
外科学   618篇
综合类   5篇
预防医学   43篇
眼科学   25篇
药学   253篇
中国医学   14篇
肿瘤学   370篇
  2023年   24篇
  2022年   23篇
  2021年   54篇
  2020年   19篇
  2019年   37篇
  2018年   34篇
  2017年   31篇
  2016年   44篇
  2015年   31篇
  2014年   55篇
  2013年   71篇
  2012年   106篇
  2011年   118篇
  2010年   43篇
  2009年   59篇
  2008年   109篇
  2007年   109篇
  2006年   159篇
  2005年   168篇
  2004年   195篇
  2003年   169篇
  2002年   169篇
  2001年   168篇
  2000年   168篇
  1999年   163篇
  1998年   54篇
  1997年   49篇
  1996年   35篇
  1995年   43篇
  1994年   31篇
  1993年   31篇
  1992年   91篇
  1991年   74篇
  1990年   69篇
  1989年   66篇
  1988年   67篇
  1987年   81篇
  1986年   59篇
  1985年   63篇
  1984年   24篇
  1983年   34篇
  1982年   11篇
  1980年   8篇
  1979年   18篇
  1978年   15篇
  1977年   23篇
  1976年   9篇
  1975年   8篇
  1974年   12篇
  1973年   10篇
排序方式: 共有3351条查询结果,搜索用时 31 毫秒
91.
Miliary tuberculosis is a potentially lethal type of tuberculosis that results from the hematogenous dissemination of Mycobacterium tuberculosis bacilli. We herein describe the case of a 34-year-old man that presented with a one-month history of cough and fever, while his sputum smear results were negative. Chest computed tomography revealed bilateral centrilobular ground-glass opacification (GGO), suggestive of hypersensitivity pneumonitis; thus, bronchoscopy was performed. Cryobiopsy specimens revealed necrotic granulomas. A re-examination of sputum after bronchoscopy identified Mycobacterium tuberculosis, and miliary tuberculosis was diagnosed. A cryobiopsy might be useful for diagnosing miliary tuberculosis pathologically, particularly when miliary nodules may be masked by GGO.  相似文献   
92.
We clarified the role of fibrinolysis in tissue-factor (TF)-induced rat disseminated intravascular coagulation (DIC) using tranexamic acid (TA). TA suppressed the elevation in D-dimer levels normally observed following TF-induced DIC, and an increase in organ dysfunction was seen. Enhanced fibrinolysis plays an important role in preventing the development of organ failure in TF-induced DIC.  相似文献   
93.
Angiogenic growth factors play important roles in angiogenic responses, such as vasculogenesis and angiogenesis in response to hypoxia. A novel angiogenic growth factor, hepatocyte growth factor (HGF), has been reported to inhibit endothelial cell death. However, its molecular mechanisms are largely unknown. Thus, we studied (1) the effects of HGF on hypoxia-induced endothelial apoptosis and (2) the molecular mechanisms of the antiapoptotic actions of HGF in endothelial cells. Severe hypoxia increased the cell death rate in human aortic endothelial cells, whereas HGF significantly attenuated cell death. In addition, hypoxic treatment resulted in a significant increase in apoptotic cells, whereas HGF could attenuate apoptosis, accompanied by attenuation of the increase in caspase-3-like activity (P<0.01). Of importance, HGF significantly increased Bcl-2, an inhibitor of apoptosis, in a dose-dependent manner under normoxic and hypoxic conditions (P<0.01), whereas hypoxic conditions resulted in a significant decrease in Bcl-2. In contrast, HGF failed to affect Bcl-xL, which is also well known as an inhibitor of apoptosis under both normoxic and hypoxic conditions, whereas Bcl-xL was significantly decreased in endothelial cells exposed to hypoxia (P<0.01). No significant change in Bax, a promoter of apoptosis, was also observed in endothelial cells under hypoxia, whereas HGF did not affect BAX: Overall, this study demonstrated that HGF prevented endothelial cell death induced by hypoxia through its antiapoptotic action. The antiapoptotic mechanisms of HGF in hypoxia-induced endothelial cell death largely depend on Bcl-2, but not Bcl-xL and BAX:  相似文献   
94.
We conducted a randomized crossover study comparing the hemopoietic effect of partially purified human urinary colony-stimulating factor (CSF-HU, an active drug) and human serum albumin (HSA, a control drug) in 24 patients with malignant lymphoma, solid tumors, or multiple myeloma who were receiving two consecutive courses of the same chemotherapeutic regimen. Patients received daily 2-4 X 10(6) units of CSF-HU or an equal amount of protein HSA for five days after the end of the courses of chemotherapy. Assignment to CSF-HU or HSA was determined by the envelope method. The average number of blood granulocytes of 24 cases on day 7 after chemotherapy was 2116 +/- 1649 in CSF-HU-infused courses, which was significantly higher than in HSA-infused courses (1520 +/- 1022) (p less than 0.05). The average time that patients had fewer than 2000 granulocytes/mm3 was 7.6 +/- 4.4 days in CSF-HU-infused courses and 10.3 +/- 5.0 days in HSA-infused courses (p less than 0.02). Fever greater than 38 degrees C was the most frequent side effect, occurring in 32% of the patients receiving CSF-HU infusions. A reduction in the neutropenic interval in CSF-HU-infused courses was observed in patients with fever, as well as in those without fever. Infusions of CSF-HU did not change the number of other hematological parameters, such as erythrocytes, platelets, monocytes, and lymphocytes. These results suggest that CSF-HU infusions may partially protect the patients from granulocytopenia after anticancer chemotherapy.  相似文献   
95.
Retroviral activation of Evi-1 gene expression is one of the most common transforming events in murine myeloid leukemias. To evaluate the role of the EVI1 gene in human acute myelogenous leukemia (AML), leukemic blasts or cell lines from 116 patients were examined. In eight patients the EVI1 gene was expressed and all but one had cytogenetically detectable translocations of chromosome 3q26 where the EVI1 gene has been localized. To identify breakpoints, a restriction map that spans 1700 kilobases (kb) of the EVI1 locus was developed by pulsed-field gel electrophoresis. In one case, t(3;3)(q21;q26), a rearrangement was localized to 170-330 kb 5' of the gene. In a second case, t(3;3)(q21;q26), there was a rearrangement 13 kb 5' of the gene. This rearrangement was cloned and shown to be due to the fusion of sequences from 3q21-22 with the EVI1 locus. In the third case, ins(3)-(q21q25q27), there was a rearrangement that mapped 150 kb downstream from the 5' end of the gene.  相似文献   
96.
Neurofibromas in the small intestine are usually accompanied by von Recklinghausen's disease (neurofibromatosis), and usually originate in the intramuscular plexus of Auerbach. We present here a solitary neurofibroma, which caused an ileocolic intussusception, originating in the submucosal plexus of Meissner in a non-neurofibromatosis patient. To our knowledge, there is no previous report of a neurofibroma originating in the plexus of Meissner. This condition was clearly confirmed by macroscopic and microscopic evaluation.  相似文献   
97.
A 58-year-old woman presented with muscle weakness, whole body myalgia, and dyspnea. On admission, neurological examination showed proximal muscle weakness in the extremities. The weakness gradually extended to the bulbar and respiratory muscles, necessitating an artificial ventilator. Serum CK level was markedly increased (33,774 IU/L; normal <150 IU/L) and myoglobinuria was noted in urinalysis. There was no sign of renal failure. Nerve conduction study was normal, but needle EMG showed myopathic changes in the weak muscles. Serological studies for virus titers showed more than a four-fold increase of cytomegalovirus (CMV) antibody titer during the disease course. The IgM anti-GM2 antibody was also elevated in the acute phase and decreased in the recovery phase. The muscle weakness and respiratory failure gradually improved after intravenous methylprednisolone administration, and the serum CK level was normalized in several days. CMV infection was thought to have played a central role in the rhabdomyolysis, leading to critical but reversible respiratory muscle paralysis.  相似文献   
98.
 Hepatocyte growth factor (HGF) is a unique growth factor with many protective functions. Previously, we demonstrated that HGF stimulated growth of endothelial cells without replication of vascular smooth muscle cells (VSMC) and that angiotensin (Ang) II significantly decreased local HGF production in VSMC. Moreover, we also reported that high glucose significantly decreased local vascular HGF production. Therefore, we examined effects of Ang II blockade on vascular HGF expression and endothelial injury in diabetic hypertensive rats. An angiotensin-converting enzyme inhibitor (quinapril) and an Ang II type 1 receptor antagonist (GA-0113) or vehicle was administrated to diabetic spontaneously hypertensive rats (SHR-DM), in whom diabetes was induced by streptozotocin. Endothelial function was evaluated by the vasodilator response to acetylcholine, and the expression of vascular HGF and its receptor, c-met, was examined by immunohistochemistry. Both quinapril and GA-0113 significantly improved the vasodilator response to acetylcholine (P < 0.01), while vehicle did not as compared to untreated normotensive Wistar-Kyoto rats (WKY). We next examined the effects of Ang II blockade on vascular HGF expression in SHR-DM. Importantly, the vascular HGF level was markedly decreased in SHR-DM as compared to WKY, while Ang II blockade by quinapril or GA-0113 significantly increased positive staining for HGF in SHR-DM. Similarly, staining of its specific receptor, c-met, was less in the blood vessels of SHR-DM as compared to WKY. In contrast, Ang II blockade also significantly increased c-met production in SHR-DM. The present data demonstrated the improvement of endothelial dysfunction by Ang II blockade in SHR-SM, accompanied by an increase in vascular HGF and c-met. Received: June 7, 2002 / Accepted: September 21, 2002 Acknowledgments We wish to thank Rie Kosai and Keiko Yamaguchi for their excellent technical assistance. This work was partially supported by grants from the Japan Health Sciences Foundation, a Grant-in-Aid from The Ministry of Public Health and Welfare, a Grant-in-Aid for the Development of Innovative Technology, a Grant-in-Aid from Japan Promotion of Science, and through Special Coordination Funds of the Ministry of Education, Culture, Sports, Science and Technology, the Japanese Government. Correspondence to N. Tomita  相似文献   
99.
Metastatic liver tumors are considered to have a tendency for expansive growth and rarely invade the bile duct. We recently encountered a resected case of liver metastasis from rectal cancer with intraluminal growth in the extrahepatic bile duct with a successful left trisegmentectomy of the liver. A 54-year-old woman underwent a posterior total pelvic exenteration for advanced rectal cancer. Ultrasonography and computed tomography four months after the first operation demonstrated a solitary occupied lesion in the liver with dilation of the left hepatic duct. Endoscopic retrograde cholangiopancreatography disclosed a filling defect in the intra- to extrahepatic bile duct. Liver metastasis from rectal cancer with intraluminal growth in the bile duct was suspected despite a consideration of primary bile duct cancer. A left trisegmentectomy of the liver and resection of the extrahepatic bile duct with a right hepatojejunostomy were performed. The tumor had invaded the intrahepatic bile duct and had developed intraluminally in the extrahepatic bile duct. Tumor thrombi were microscopically found in the bile duct of the left caudal lobe. Liver metastasis arising from colorectal cancer with intraluminal growth in the bile duct is rare, however we encountered such a case with a successful resection involving a left trisegmentectomy of the liver.  相似文献   
100.
OBJECTIVE: Cardiac allograft arteriosclerosis, which limits long-term survival of recipients, cannot be prevented by conservative therapies. The arteriopathy is characterized by diffuse intimal thickening comprised of proliferative smooth muscle cells (SMCs). Cell death is a prominent feature of atherosclerosis; Bcl-x is one of the anti-apoptotic mediators. METHODS: To test the hypothesis that antisense bcl-x oligodeoxynucleotide (ODN) is effective in preventing intimal hyperplasia through enhancing apoptosis after cardiac transplantation, we performed single intraluminal delivery of antisense bcl-x ODN into murine cardiac allografts (n = 9). DBA/2 (H-2d) hearts were transplanted into B10.D2 (H-2d) mice. Sense bcl-x ODN (n = 8) and no treatment (n = 8) studies were also performed. RESULTS: Allografts were harvested at 4 weeks after transplantation; all allografts kept beating throughout the period. Coronary intimal thickening had developed in nontreated and sense ODN transfected allografts at 4 weeks after transplantation with enhanced expression of Bcl-x and cell adhesion molecules, and suppressed apoptosis. However, antisense bcl-x ODN prevented neointimal formation through enhanced apoptosis. CONCLUSION: These results indicate that apoptosis of vascular SMCs induced by Bcl-x is associated with initial hyperplasia after heart transplantation. Antisense bcl-x ODN inhibits SMC proliferation by inducing apoptosis in graft coronary arteries.  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