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   1300篇
  免费   72篇
  国内免费   1篇
耳鼻咽喉   122篇
儿科学   11篇
妇产科学   26篇
基础医学   159篇
口腔科学   45篇
临床医学   91篇
内科学   275篇
皮肤病学   32篇
神经病学   125篇
特种医学   46篇
外科学   114篇
综合类   6篇
一般理论   1篇
预防医学   54篇
眼科学   87篇
药学   80篇
中国医学   1篇
肿瘤学   98篇
  2023年   7篇
  2022年   16篇
  2021年   39篇
  2020年   19篇
  2019年   31篇
  2018年   39篇
  2017年   24篇
  2016年   29篇
  2015年   39篇
  2014年   42篇
  2013年   46篇
  2012年   78篇
  2011年   81篇
  2010年   58篇
  2009年   27篇
  2008年   51篇
  2007年   55篇
  2006年   50篇
  2005年   52篇
  2004年   45篇
  2003年   48篇
  2002年   47篇
  2001年   36篇
  2000年   48篇
  1999年   39篇
  1998年   11篇
  1997年   6篇
  1996年   17篇
  1995年   5篇
  1994年   6篇
  1992年   21篇
  1991年   28篇
  1990年   26篇
  1989年   23篇
  1988年   16篇
  1987年   16篇
  1986年   12篇
  1985年   16篇
  1984年   9篇
  1983年   7篇
  1982年   15篇
  1981年   8篇
  1980年   7篇
  1979年   13篇
  1978年   6篇
  1974年   6篇
  1973年   5篇
  1969年   5篇
  1965年   4篇
  1957年   5篇
排序方式: 共有1373条查询结果,搜索用时 20 毫秒
41.
42.
The authors present a modification of the preauricular approach that improves the exposure of the condyle whilst reducing diacapitular and condylar neck fractures. The incision is a combination of the hockey-stick and endaural incisions. Its inferior part runs within the ear on the posterior face of the tragus; the tragal cartilage is transected together with the retrotragal skin and included in the anterior skin flap. Between May 2009 and December 2010, 16 patients with diacapitular or condylar neck fractures were treated with this approach. All patients showed good occlusion postoperatively and satisfactory aesthetic results. No infection or cartilage necrosis was observed in this series. This approach improves the exposure of the condylar head during the reduction of diacapitular and condylar neck fractures, ensuring easier internal fixation and good cosmetic results.  相似文献   
43.
The RTS,S/AS02A protein-based vaccine consistently demonstrates significant protection against infection with Plasmodium falciparum malaria and also against clinical malaria and severe disease in children in areas of endemicity. Here we demonstrate with rhesus macaques that priming with a replication-defective human adenovirus serotype 35 (Ad35) vector encoding circumsporozoite protein (CS) (Ad35.CS), followed by boosting with RTS,S in an improved MPL- and QS21-based adjuvant formulation, AS01B, maintains antibody responses and dramatically increases levels of T cells producing gamma interferon and other Th1 cytokines in response to CS peptides. The increased T-cell responses induced by the combination of Ad35.CS and RTS,S/AS01B are sustained for at least 6 months postvaccination and may translate to improved and more durable protection against P. falciparum infection in humans.  相似文献   
44.
Synthetic peptides have frequently replaced the more costly recombinant proteins or viral lysates as the antigens of choice for detection of antibodies to human immunodeficiency viruses. However, development of an assay that is sensitive to all the types and groups of HIV, including the divergent strains of HIV-1 group O, group N, and HIV-2, would require many peptides derived from different types and groups of HIV. Combining multiple peptide antigens may reduce the analytical sensitivity of the individual peptide due to the competition for binding to the solid surface when used in an enzyme immunoassay format. In this study, we developed and evaluated two chimeric multiple antigenic peptides (CMAP) for simultaneous detection of specific antibodies to HIV-1 groups M, N, O, and HIV-2. Both CMAPs correctly identified 304 known HIV positive serum or plasma specimens (260 HIV-1 group M of varying subtypes, 3 group O, and 41 HIV-2) and one chimpanzee serum specimen (group N) and all 66 known HIV negative specimens. CMAP performance was superior to the corresponding individual linear peptides or a linear peptide mixture. The results indicate that CMAPs are useful for the development of highly sensitive and specific assays for the detection of infections caused by HIV-1, including group M, N, and O, and HIV-2.  相似文献   
45.
Glutathione degradable polyurethane-polyurea nanoparticles (PUUa NP) with a disulfide-rich multiwalled structure and a cyclic RGD peptide as a targeting moiety were synthesized, incorporating a very lipophilic chemotherapeutic drug named Plitidepsin. In vitro studies indicated that encapsulated drug maintained and even improved its cytotoxic activity while in vivo toxicity studies revealed that the maximum tolerated dose (MTD) of Plitidepsin could be increased three-fold after encapsulation. We also found that pharmacokinetic parameters such as maximum concentration (Cmax), area under the curve (AUC) and plasma half-life were significantly improved for Plitidepsin loaded in PUUa NP. Moreover, biodistribution assays in mice showed that RGD-decorated PUUa NP accumulate less in spleen and liver than non-targeted conjugates, suggesting that RGD-decorated nanoparticles avoid sequestration by macrophages from the reticuloendothelial system. Overall, our results indicate that polyurethane-polyurea nanoparticles represent a very valuable nanoplatform for the delivery of lipophilic drugs by improving their toxicological, pharmacokinetic and whole-body biodistribution profiles.  相似文献   
46.
The association between tumor size and survival in patients with intrahepatic cholangiocarcinoma (ICC) undergoing surgical resection is controversial. We sought to define the incidence of major and microscopic vascular invasion relative to ICC tumor size, and identify predictors of microscopic vascular invasion in patients with ICC ≥5 cm. A total of 443 patients undergoing surgical resection for ICC between 1973 and 2011 at one of 11 participating institutions were identified. Clinical and pathologic data were evaluated using uni- and multivariate analyses. As tumor sized increased, the incidence of microscopic vascular invasion increased: <3 cm, 3.6 %; 3–5 cm, 24.7 %; 5–7 cm, 38.3 %; 7–15 cm, 32.9 %, ≥15 cm, 55.6 %; (p?<?0.001). Increasing tumor size was also found to be associated with worsening tumor grade. The incidence of poorly differentiated tumors increased with increasing ICC tumor size: <3 cm, 9.7 %; 3–5 cm, 19.8 %; 5–7 cm, 24.2 %; 7–15 cm, 21.1 %; >15 cm, 31.6 % (p?=?0.04). The presence of perineural invasion (odds ratio [OR]?=?2.98) and regional lymph node metastasis (OR?=?4.43) were independently associated with an increased risk of microscopic vascular invasion in tumors ≥5 cm (both p?<?0.05). Risk of microscopic vascular invasion and worse tumor grade increased with tumor size. Large tumors likely harbor worse pathologic features; this information should be considered when determining therapy and prognosis of patients with large ICC.  相似文献   
47.
At present surgery is accepted as the most effective mode of therapy for carcinoma of the lung. Because the lack of respiratory reserve is the major determinant of postoperative function, it is useful to identify the patient, who is at significant risk. Eighteen patients with lung cancer (mean age = 56 +/- 6.5 years) were studied preoperatively (preop) and postoperative (postop) (three to four months after lung resection) by spirometry, measurement of arterial blood gases, and quantitative lung scanning (99mTc). A predicted postoperative value of some variables was calculated by the formula: postop value = preop value x % function of regions of lung not resected. The correlation coefficient between the predicted (pred) and postoperatively observed (observ) values VC = vital capacity, FEV1 = forced expiratory volume in 1 second) is: VC pred/VC observ r = 0.83 p less than 0.001 FEV1 pred/FEV1 observ r = 0.82 p less than 0.001. The authors' results agree with earlier reports and show that the method used can accurately predict the postoperative respiratory function in patients undergoing lung resection (pneumonectomy or lobectomy). A predicted FEV1 of 0.8 L does not permit a surgical program, because, below this level, carbon dioxide retention becomes more frequent and exercise intolerance is increasingly severe (poor quality of life). The method proposed to predict the postoperative respiratory function is simple and routinely useful. The authors choose a perfusion instead of ventilation scan, because the former provides similar predicted postoperative data, and can be done routinely.  相似文献   
48.
Wedged hepatic venous pressure (WHVP) is equivalent to portal venous pressure in patients with alcoholic liver diseases. However, it may underestimate portal pressure in nonalcoholics, which is important because hepatitis C virus (HCV) infection is a frequent cause of chronic liver disease. We investigated the agreement between directly measured portal pressure and WHVP in alcoholic and HCV-related liver diseases. Seventy-one patients with liver disease resulting from HCV infection (n = 32), alcohol (n = 25), or both (n = 14) underwent simultaneous measurements of WHVP (by hepatic vein catheterization) and portal pressure (by direct puncture). In 9 patients, measurements were repeated 20 minutes after acute iv propranolol administration. WHVP showed an excellent agreement with portal pressure in patients with cirrhosis resulting from either HCV, alcohol or both (intraclass correlation coefficient: 0.94, 0.93, and 0.97, respectively; P <.001). A discrepancy of >/=5 mm Hg was observed in 7 cases. WHVP underestimated portal pressure in only 1 case and exceeded portal pressure by >/=5 mm Hg in 6 patients. The WHVP response to propranolol closely and significantly correlated with changes in portal pressure (intraclass correlation coefficient: 0.87; P <.004). The simple and safe measurement of WHVP accurately reflects portal pressure in alcoholic and HCV-related liver disease. This technique also allows us to accurately assess the portal pressure response to propranolol in both alcoholic and HCV-related cirrhosis.  相似文献   
49.
50.
Richter syndrome (RS) is an uncommon evolution of chronic lymphocytic leukaemia (CLL) with a dismal prognosis. Clinical-biological features predicting outcome and best therapeutic approach for these patients remain to be established. In this study, 128 patients with RS, including 112 diffuse large B-cell lymphoma (DLBCL)-type RS, 15 Hodgkin lymphoma (HL)-type RS, and one plasmablastic lymphoma, were identified in 11 centres of the Spanish CLL Study Group (GELLC). The median overall survival (OS) was 5·9 months for DLBCL-type RS and 30·8 months for HL-type RS. Eastern Cooperative Oncology Group Performance Status, haemoglobin level, platelet count, serum lactate dehydrogenase and β2-microglobulin levels, tumour protein p53 (TP53) abnormalities in the CLL clone concomitant to RS, number of prior therapies, and clonal relationship between CLL and RS, were associated with OS in patients with DLBCL-type RS. A platelet count of <100 × 109/l, prior CLL therapy (0 vs. ≥1), and presence of TP53 alterations maintained an independent prognostic impact in the multivariate analysis. Patients without any of these factors had a better clinical outcome, with a median OS of 75·3 months, while patients with one or two or more of these factors presented a median OS of 25·5 and 3 months, respectively. Although OS of patients with RS is generally poor, a proportion of patients achieved prolonged survival. Treatment of RS remains a medical need, and further therapeutic approaches with novel therapies are warranted.  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