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   10227篇
  免费   577篇
  国内免费   86篇
耳鼻咽喉   78篇
儿科学   317篇
妇产科学   215篇
基础医学   1173篇
口腔科学   444篇
临床医学   926篇
内科学   2459篇
皮肤病学   230篇
神经病学   818篇
特种医学   470篇
外科学   1642篇
综合类   18篇
一般理论   1篇
预防医学   540篇
眼科学   93篇
药学   469篇
中国医学   11篇
肿瘤学   986篇
  2024年   17篇
  2023年   129篇
  2022年   224篇
  2021年   441篇
  2020年   208篇
  2019年   334篇
  2018年   408篇
  2017年   267篇
  2016年   276篇
  2015年   306篇
  2014年   399篇
  2013年   467篇
  2012年   677篇
  2011年   739篇
  2010年   434篇
  2009年   399篇
  2008年   625篇
  2007年   610篇
  2006年   579篇
  2005年   579篇
  2004年   524篇
  2003年   472篇
  2002年   388篇
  2001年   177篇
  2000年   148篇
  1999年   141篇
  1998年   79篇
  1997年   70篇
  1996年   58篇
  1995年   45篇
  1994年   38篇
  1993年   40篇
  1992年   70篇
  1991年   48篇
  1990年   51篇
  1989年   44篇
  1988年   40篇
  1987年   35篇
  1986年   38篇
  1985年   26篇
  1984年   22篇
  1983年   25篇
  1982年   19篇
  1980年   11篇
  1979年   15篇
  1977年   16篇
  1975年   14篇
  1974年   13篇
  1973年   13篇
  1968年   16篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
81.
BACKGROUND: There are unresolved issues regarding the security of liver transplantation with non-heart-beating donors (NHBDs). Recently, an increased incidence of biliary complications, mainly intrahepatic ischemic-type biliary strictures, has been described after controlled NHBDs. METHODS: We studied the incidence and risk factors for biliary complications among uncontrolled NHBDs recipients compared with a large population of HBD recipients. RESULTS: Overall, 16.8% of patients in the HBD group and 41.7% of patients in the NHBD group suffered any type of biliary complication (P=0.66). However, the incidence of nonanastomotic biliary strictures was significantly greater in the NHBD group (P<0.001). Multivariate analysis showed that independent risk factors for nonanastomotic strictures were hepatic artery thrombosis (relative risk; 98.7) and receiving a liver from a NHBD (relative risk; 47.1). CONCLUSIONS: If this type of donors is accepted as a source of liver organs, the high incidence of biliary complications should be considered and efforts should be made to decrease ischemic injury.  相似文献   
82.
T Teruel  R Hernandez  M Lorenzo 《Diabetes》2001,50(11):2563-2571
Tumor necrosis factor (TNF)-alpha causes insulin resistance on glucose uptake in fetal brown adipocytes. We explored the hypothesis that some effects of TNF-alpha could be mediated by the generation of ceramide, given that TNF-alpha treatment induced the production of ceramide in these primary cells. A short-chain ceramide analog, C2-ceramide, completely precluded insulin-stimulated glucose uptake and insulin-induced GLUT4 translocation to plasma membrane, as determined by Western blot or immunofluorescent localization of GLUT4. These effects were not produced in the presence of a biologically inactive ceramide analog, C2-dihydroceramide. Analysis of the phosphatidylinositol (PI) 3-kinase signaling pathway indicated that C2-ceramide precluded insulin stimulation of Akt kinase activity, but not of PI-3 kinase or protein kinase C-zeta activity. C2-ceramide completely abolished insulin-stimulated Akt/protein kinase B phosphorylation on regulatory residues Thr 308 and Ser 473, as did TNF-alpha, and inhibited insulin-induced mobility shift in Akt1 and Akt2 separated in PAGE. Moreover, C2-ceramide seemed to activate a protein phosphatase (PP) involved in dephosphorylating Akt because 1) PP2A activity was increased in C2-ceramide- and TNF-alpha-treated cells, 2) treatment with okadaic acid concomitantly with C2-ceramide completely restored Akt phosphorylation by insulin, and 3) transient transfection of a constitutively active form of Akt did not restore Akt activity. Our results indicate that ceramide produced by TNF-alpha induces insulin resistance in brown adipocytes by maintaining Akt in an inactive dephosphorylated state.  相似文献   
83.
The use of nonpenetrating clips (NPC) for vascular anastomosis is quickly becoming accepted. Studies attest to decreased anastomotic time, comparable patency rates, and decreased blood loss. Few human studies on the use of NPC have been done to date. The purpose of this study was to evaluate primary patency rates, operative time, and complications associated with NPC compared to those with standard sutures for arterial venous graft (AVG). We retrospectively reviewed the clinical course of 82 patients with a mean age of 45 years (range, 22 to 87) from February 1996 to July 1999. All patients underwent upper extremity AVG construction. The procedures were performed at a single institution, by a single, well-experienced surgeon who has extensive experience with NPC. Primary patency rates, operative time, and complications were analyzed. Overall thrombotic incidence of AVG when NPC were used (27/48, 56%) was similar to that of sutures (17/34, 50%). Thrombotic incidence within the first year was similar as well (23/48, 48% and 13/34, 38%). The mean time to primary thrombosis was similar in both groups (6.9 and 6.8 months). The operative time required to construct an AVG with NPC (83 min) was significantly less than that with sutures (96 min) (p = 0.015). There was no significant difference in incidence of graft infection or pseudoaneurysm formation. NPC for AVG reduced operative time and resulted in primary patency and complication rates similar to those associated with use of sutures. The mean time to primary thrombosis was similar for both groups. Our findings suggest an intimai hyperplastic response of a similar nature resulting in thrombosis of both NPC and sutured AVGs. Presented at the Twenty-fifth Annual Meeting of the Peripheral Vascular Surgery Society, Toronto, Ontario, Canada, June 10, 2000.  相似文献   
84.
The surgical specialty of critical care has evolved into a field where the surgeon manages complex medical and surgical problems in critically ill patients. As a specialty, surgical critical care began when acutely ill surgical patients were placed in a designated area within a hospital to facilitate the delivery of medical care. As technology evolved to allow for development of increasingly intricate and sophisticated adjuncts to care, there has been recognition of the importance of physician availability and continuity of care as key factors in improving patient outcomes. Guidelines and protocols have been established to ensure quality improvement and are essential to licensing by state and national agencies. The modern ICU team provides continuous daily care to the patient in close communication with the primary operating physician. While the ultimate responsibility befalls the primary physician who performed the preoperative evaluation and operative procedure, the intensivist is expected to establish and enforce protocols, guidelines and patient care pathways for the critical care unit. It is difficult to imagine modern surgical ICU care without the surgical critical care specialist at the helm.  相似文献   
85.
From February 2002 to December 2005, 424 operations for thyroid disease were performed in our institute. Twenty-two patients were suffering from Basedow's disease, 14 female and 8 male, mean age 36 years (range: 23 to 53 years). In each patient the diagnosis of Basedow's disease was made according to common clinical and laboratory criteria, by evaluation of the thyroid hormones, TSH and TRAB. Before operation all patients were rendered euthyroid with antithyroid drug treatment. Fourteen total thyroidectomies (64%) and 8 near-total thyroidectomies (36%) were performed. Postoperative thyroid function status was evaluated before, 3-4 weeks after the operation and then 3, 6,12 and 24 months postoperatively. The patients were classified as euthyroid (FT3-FT4 and TSH normal), hypothyroid (FT3 and/or FT4 reduced and TSH increased), or hyperthyroid (FT3-FT4 increased). In expert hands, surgical treatment appears to be capable of curing the hyperthyroidism of Basedow's disease effectively, with a very low and largely acceptable risk of complications. Among the different types of surgery, total thyroidectomy and near-total thyroidectomy are equally appropriate to ensure there is no risk of recurrence of hyperthyroidism.  相似文献   
86.
Re-resection for gallbladder carcinoma incidentally discovered after cholecystectomy is routinely advocated. However, the incidence of finding additional disease at the time of re-resection remains poorly defined. Between 1984 and 2006, 115 patients underwent re-resection at six major hepatobiliary centers for gallbladder carcinoma incidentally discovered during cholecystectomy. Data on clinicopathologic factors, operative details, TNM tumor stage, and outcome were collected and analyzed. Data on the incidence and location of residual/additional carcinoma discovered at the time of re-resection were also recorded. On pathologic analysis, T stage was T1 7.8%, T2 67.0%, and T3 25.2%. The median time from cholecystectomy to re-resection was 52 days. At the time of re-resection, hepatic surgery most often consisted of formal segmentectomy (64.9%). Patients underwent lymphadenectomy (LND) (50.5%) or LND + common bile duct resection (43.3%). The median number of lymph nodes harvested was 3 and did not differ between LND alone (n = 3) vs LND + common duct resection (n = 3) (P = 0.35). Pathology from the re-resection specimen noted residual/additional disease in 46.4% of patients. Of those patients staged as T1, T2, or T3, 0, 10.4, and 36.4%, respectively, had residual disease within the liver (P = 0.01). T stage was also associated with the risk of metastasis to locoregional lymph nodes (lymph node metastasis: T1 12.5%; T2 31.3%, T3 45.5%; P = 0.04). Cystic duct margin status predicted residual disease in the common bile duct (negative cystic duct, 4.3% vs positive cystic duct, 42.1%) (P = 0.01). Aggressive re-resection for incidental gallbladder carcinoma is warranted as the majority of patients have residual disease. Although common duct resection does not yield a greater lymph node count, it should be performed at the time of re-resection for patients with positive cystic duct margins because over one-third will have residual disease in the common bile duct. Presented at the 48th Annual Meeting of the Society for Surgery of the Alimentary Tract at Digestive Week 2007, Plenary Session, Washington, DC, March 23, 2007.  相似文献   
87.
Protein-tyrosine phosphatase (PTP)1B is a negative regulator of insulin signaling and a therapeutic target for type 2 diabetes. In this study, we have assessed the role of PTP1B in the insulin sensitivity of skeletal muscle under physiological and insulin-resistant conditions. Immortalized myocytes have been generated from PTP1B-deficient and wild-type neonatal mice. PTP1B(-/-) myocytes showed enhanced insulin-dependent activation of insulin receptor autophosphorylation and downstream signaling (tyrosine phosphorylation of insulin receptor substrate [IRS]-1 and IRS-2, activation of phosphatidylinositol 3-kinase, and serine phosphorylation of AKT), compared with wild-type cells. Accordingly, PTP1B(-/-) myocytes displayed higher insulin-dependent stimulation of glucose uptake and GLUT4 translocation to the plasma membrane than wild-type cells. Treatment with tumor necrosis factor-alpha (TNF-alpha) induced insulin resistance on glucose uptake, impaired insulin signaling, and increased PTP1B activity in wild-type cells. Conversely, the lack of PTP1B confers protection against insulin resistance by TNF-alpha in myocyte cell lines and in adult male mice. Wild-type mice treated with TNF-alpha developed a pronounced hyperglycemia along the glucose tolerance test, accompanied by an impaired insulin signaling and increased PTP1B activity in muscle. However, mice lacking PTP1B maintained a rapid clearance of glucose and insulin sensitivity and displayed normal muscle insulin signaling regardless the presence of TNF-alpha.  相似文献   
88.
89.

Context

The European Association of Urology Renal Cell Carcinoma (RCC) Guideline Panel has prepared evidence-based guidelines and recommendations for the management of RCC.

Objective

To provide an updated RCC guideline based on standardised methodology including systematic reviews, which is robust, transparent, reproducible, and reliable.

Evidence acquisition

For the 2019 update, evidence synthesis was undertaken based on a comprehensive and structured literature assessment for new and relevant data. Where necessary, formal systematic reviews adhering to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were undertaken. Relevant databases (Medline, Cochrane Libraries, trial registries, conference proceedings) were searched until June 2018, including randomised controlled trials (RCTs) and retrospective or controlled studies with a comparator arm, systematic reviews, and meta-analyses. Where relevant, risk of bias (RoB) assessment, and qualitative and quantitative syntheses of the evidence were performed. The remaining sections of the document were updated following a structured literature assessment. Clinical practice recommendations were developed and issued based on the modified GRADE framework.

Evidence synthesis

All chapters of the RCC guidelines were updated based on a structured literature assessment, for prioritised topics based on the availability of robust data. For RCTs, RoB was low across studies. For most non-RCTs, clinical and methodological heterogeneity prevented pooling of data. The majority of included studies were retrospective with matched or unmatched cohorts, based on single- or multi-institutional data or national registries. The exception was for the treatment of metastatic RCC, for which there were several large RCTs, resulting in recommendations based on higher levels of evidence.

Conclusions

The 2019 RCC guidelines have been updated by the multidisciplinary panel using the highest methodological standards. These guidelines provide the most reliable contemporary evidence base for the management of RCC in 2019.

Patient summary

The European Association of Urology Renal Cell Carcinoma Guideline Panel has thoroughly evaluated the available research data on kidney cancer to establish international standards for the care of kidney cancer patients.  相似文献   
90.
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