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   128785篇
  免费   11053篇
  国内免费   8077篇
耳鼻咽喉   1055篇
儿科学   1572篇
妇产科学   2327篇
基础医学   15084篇
口腔科学   2092篇
临床医学   16793篇
内科学   21024篇
皮肤病学   1462篇
神经病学   7030篇
特种医学   4341篇
外国民族医学   70篇
外科学   13444篇
综合类   19130篇
现状与发展   24篇
一般理论   5篇
预防医学   7921篇
眼科学   3709篇
药学   12933篇
  157篇
中国医学   6234篇
肿瘤学   11508篇
  2024年   1412篇
  2023年   2425篇
  2022年   4859篇
  2021年   6028篇
  2020年   4513篇
  2019年   4134篇
  2018年   4164篇
  2017年   3755篇
  2016年   3518篇
  2015年   5264篇
  2014年   6582篇
  2013年   6126篇
  2012年   8960篇
  2011年   9784篇
  2010年   5965篇
  2009年   4742篇
  2008年   6522篇
  2007年   6514篇
  2006年   6549篇
  2005年   6486篇
  2004年   4465篇
  2003年   4219篇
  2002年   3561篇
  2001年   3227篇
  2000年   3321篇
  1999年   3444篇
  1998年   2246篇
  1997年   2169篇
  1996年   1565篇
  1995年   1458篇
  1994年   1269篇
  1993年   819篇
  1992年   1228篇
  1991年   1075篇
  1990年   931篇
  1989年   823篇
  1988年   712篇
  1987年   668篇
  1986年   508篇
  1985年   463篇
  1984年   250篇
  1983年   178篇
  1982年   118篇
  1981年   116篇
  1980年   78篇
  1979年   120篇
  1978年   59篇
  1976年   52篇
  1975年   55篇
  1974年   65篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
目的 探讨肾小球疾病免疫球蛋白、补体水平与免疫病理的相关性.方法 112 例肾小球疾病患者,14 例健康人测定血清免疫球蛋白及补体,112 例肾小球疾病患者,112 例患者行肾活组织病理检查.结果 112 例肾小球疾病患者 IgG 升高 11 例(9.82%),降低 29 例(25.89%),IgA 升高 33 例(29.46%),降低 2 例(1.79%).IgM 升高 7 例(6.25%),降低 3 例(2.68%),三种免疫球蛋白的变化有显著差异(x2=70.587,P=O.000);C3 减低 29 例(25.89%),C4减低 32 例(28.57%),两者比较无显著差异(X2=0.203,P=0.653).免疫荧光阳性率依次为C3(50%)>lgA(49.11%)>IgG(40.18%)>lgM(21.43%)>C4(14.29%)(x2=49.303,P=0.000);免疫荧光 IgA 阳性者血清 lgA 水平较阴性者高(P=0.042),C3、CA阳性者血清 C3、c4 水平较阴性者低(P=0,P=0.007),IgG、IgM 阳性者血清 IgG、lgM 水平与阴性者比较无差异(P=0.136,P=0.383).结论 肾小球疾病存在体液免疫紊乱,测定血清免疫球蛋白、补体及行肾组织免疫病检有助于了解体液免疫状况,估计疾病活动度,判断疗效,但两种检查之间无明显的相关性,可相互补充,不能相互替代.  相似文献   
992.
Objective To investigate the clinical pathologic characters of colorectal cancer with simultaneous hepatic metastasis and the prognosis. Methods From Aug. 1994 to Dec. 2006, 2019 cases of colorectal carcinoma were admitted, among them there were 166 patients of colorectal cancer with synchronous liver metastases receiving surgical therapy. Results were analyzed retrospectively using the software of SPSS. Results These 166 patients with synchronous liver metastases from colorectal cancer accounted for 8.1% of all 2019 patients of colorectal cancer admitted. Multivariate analysis demonstrated that CEA level before surgery、depth of invasion、 pathological type and Ducks' stage were the key risk factors predicting simultaneous liver metastasis from colorectal cancer. The survival rates at 1, 3 and 5 years were 69%, 21%, and 9% respectively. There was significant difference among the different liver metastasis group of H1, H2 and H3(X2=23.35, P<0.01). The survival rates of patients undergoing radical resection was higher than those undergoing palliative resection (PR)and by-pass operation or feeding neostomy(BP/ FN)(X2= 21.18,P<0.01). PR improved short-term prognosis but did not improve long-term survival compared with BP/FN group(P=0.13). Conclusion Colorectal cancer with synchronous liver metastases has poor clinic pathological characters. Different degree of liver metastasis result in different prognosis.Radical resection leads to a better prognosis. Palliative resection can improve short-term prognosis and life quality but can't improve long-term survival.  相似文献   
993.
BACKGROUND: Systemically administered insulin has been shown to accelerate wound healing. To minimize the hypoglycemic and hypokalemic effects of insulin, we investigated a new route of insulin administration by local injection into skin wounds. MATERIALS AND METHODS: Partial thickness skin donor site wounds were created on the backs of adult rabbits with a dermatome set at 0.015 inch. The wounds were covered by Aquaphor gauze (Smith and Nephew, Largo, FL), and OpSite membrane (Smith and Nephew, Hull, United Kingdom) and protected by rabbit jackets. Long-acting insulin-zinc suspension was selected for local injection. In study 1, insulin was injected into the wound at different doses, and the concentrations of blood glucose and wound insulin were measured to determine the proper dose and injection frequency. In study 2, wound healing days were compared between two groups (n = 7 each) receiving local injection of either insulin-zinc or zinc alone as control. Based on the results from study 1, a dose of 0.25 units of long-acting insulin-zinc suspension was injected into the wound every other day in the insulin group. RESULTS: After injection, 0.25 units of insulin decreased blood glucose concentration (minimum 60 mg/dL) during the first 3 h, which then returned to the preinjection level (80 mg/dL). One injection maintained wound insulin concentration above 50 muU/mL for more than 24 h. With local injection of 0.25 units insulin-zinc every other day, the wound healing time was 11.2 +/- 2.3 d, which was faster (P = 0.02) than 15.1 +/- 4.1 d in the control group. CONCLUSION: Local injection of long-acting insulin-zinc suspension accelerated skin wound healing without major systemic side effects, demonstrating its potential usefulness in burn treatment.  相似文献   
994.
BACKGROUND: Isoniazid (INH) therapy for tuberculosis carries a known risk for hepatoxicity, and leads to hepatic failure in a small subset of patients. This incidence has been described for adults, but is uncertain in children. Our aim was to estimate the incidence of pediatric referrals for INH-related liver failure, and to describe the characteristics and outcomes of these patients. METHODS: The 84 U.S. centers performing pediatric liver transplants between 1987 and 1997 were surveyed regarding patients with INH-induced liver failure. Additional transplant statistics were obtained from the United Network for Organ Sharing. Estimates of the number of children taking preventive INH were derived from a nationwide public health database. RESULTS: Twenty cases of INH-related liver failure were found during a 10-year period. Four patients (20%) recovered spontaneously; 10 (50%) underwent orthotopic liver transplantation (OLT), while six (30%) died awaiting OLT. Mean age at presentation was 9.8 years (range 1.3-17). Mean length of INH therapy was 3.3 months (range 0.5-9). Notably, five patients seen for symptoms of hepatitis were initially told not to stop treatment. INH-associated liver failure accounted for 0.2% (8 of 4679) of all pediatric OLTs, and 14% (8/56) of transplants for drug hepatoxicity. The estimated incidence of liver failure was up to 3.2/100,000 for children on prophylactic INH. CONCLUSIONS: While INH-associated liver failure in children is rare, discontinuation at the onset of symptoms does not assure recovery. This indicates a need for increased awareness of hepatotoxicity risk, expanded biochemical monitoring for children receiving INH, and prompt withdrawal in symptomatic patients.  相似文献   
995.
Recent studies confirmed that the new cell survival signal pathway of Insulin-PI3K-Akt exerted cyto-protective actions involving anti-apoptosis. This study was undertaken to investigate the potential neuroprotective effects of insulin in the pathogenesis of spinal cord injury (SCI) and evaluate its therapeutic effects in adult rats. SCI was produced by extradural compression using modified Allen's stall with damage energy of 40 g-cm force. One group of rats was subjected to SCI in combination with the administration of recombinant human insulin dissolved in 50% glucose solution at the dose of 1 IU/kg day, for 7 days. At the same time, another group of rats was subjected to SCI in combination with the administration of an equal volume of sterile saline solution. Functional recovery was evaluated using open-field walking, inclined plane tests, and motor evoked potentials (MEPs) during the first 14 days post-trauma. Levels of protein for B-cell lymphoma/leukemia-2 gene (Bcl-2), Caspase-3, inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) were quantified in the injured spinal cord by Western blot analysis. Neuronal apoptosis was detected by TUNEL, and spinal cord blood flow (SCBF) was measured by laser-Doppler flowmetry (LDF). Ultimately, the data established the effectiveness of insulin treatment in improving neurologic recovery, increasing the expression of anti-apoptotic bcl-2 proteins, inhibiting caspase-3 expression decreasing neuronal apoptosis, reducing the expression of proinflammatory cytokines iNOS and COX-2, and ameliorating microcirculation of injured spinal cord after moderate contusive SCI in rats. In sum, this study reported the beneficial effects of insulin in the treatment of SCI, with the suggestion that insulin should be considered as a potential therapeutic agent.  相似文献   
996.
997.
Osteogenesis is synergistically enhanced by the combined effect of complimentary factors. This study showed that Nell-1 and BMP-2 synergistically enhanced osteogenic differentiation of myoblasts and phosphorylated the JNK MAPK pathway. The findings are important because of the osteochondral specificity of Nell-1 signaling and the potential therapeutic effects of coordinated BMP-2 and Nell-1 delivery. INTRODUCTION: BMPs play an important role in the migration and proliferation of mesenchymal cells and have a unique ability to alter the differentiation of mesenchymal cells toward chondrogenic and osteogenic lineages. Signaling upstream of Cbfa1/Runx2, BMPs effects are not limited to cells of the osteoblast lineage. Thus, additional osteoblast-specific factors that could synergize with BMP-2 would be advantageous for bone regeneration procedures. NELL-1 (NEL-like molecule-1; NEL [a protein strongly expressed in neural tissue encoding epidermal growth factor like domain]) is a novel growth factor believed to preferentially target cells committed to the osteochondral lineage. MATERIALS AND METHODS: C2C12 myoblasts were transduced with AdLacZ, AdNell-1, AdBMP-2, or AdNell-1+AdBMP-2 overexpression viruses. Effects were studied by cell morphology, alkaline phosphatase activity, osteopontin production, and MAPK signaling. Additionally, in a nude mouse model, viruses were injected into leg muscles, and new bone formation was examined after 2 and 8 wk. RESULTS: C2C12 myoblasts co-transduced with AdNell-1+AdBMP-2 showed a synergistic effect on osteogenic differentiation as detected by alkaline phosphatase activity and osteopontin production. Nell-1 stimulation on AdNell-1 + AdBMP-2 preconditioned C2C12 cells revealed significant activation of the non-BMP-2 associated c-Jun N-terminal kinase (JNK) MAPK signaling pathway, but not the p38 or extracellular signal-regulated kinase (ERK1/2) MAPK pathways. Importantly Nell-1 alone did not induce osteogenic differentiation of myoblasts. In a nude mouse model, injection of AdNell-1 alone stimulated no bone formation within muscle; however, injection of AdNell-1+AdBMP-2 stimulated a synergistic increase in bone formation compared with AdBMP-2 alone. CONCLUSIONS: These findings are important because of the confirmed osteochondral specificity of Nell-1 signaling and the potential therapeutic effects of enhanced BMP-2 action with coordinated Nell-1 delivery.  相似文献   
998.
999.
重症急性胰腺炎死亡的高危因素分析   总被引:11,自引:0,他引:11  
Sun B  Dong CG  Wang G  Jiang HC  Meng QH  Li J  Liu J  Wu LF 《中华外科杂志》2007,45(23):1619-1622
目的探讨与重症急性胰腺炎(SAP)死亡相关的高危因素。方法回顾性分析2001年1月至2005年10月收治的141例SAP患者的临床资料。将患者分为死亡组和生存组,对可能影响SAP预后的15个因素采用Logistic回归分析。结果141例SAP患者中死亡34例(24.1%)。死亡组患者在年龄、体重指数、住院时间、APACHEⅡ评分和并发多器官功能障碍综合征(MODS)、腹腔室隔综合征(ACS)等方面与生存组相比差异有统计学意义(P〈0.05)。多因素分析显示,MODS(OR=67.358,P〈0.01)、APACHEII评分(OR=9.716,P〈0.01)和ACS(OR=5.775,P〈0.05)是早期影响SAP预后的独立危险因素;胰腺感染(OR=9.652,P〈0.01)、MODS(OR=5.212,P〈0.05)和腹腔出血(OR=4.707,P〈0.05)则是后期影响SAP预后的独立危险因素。结论SAP早期死亡的主要原因是MODS,特别是呼吸功能障碍和肾功能障碍,而后期死亡的主要原因是感染、MODS和腹腔出血。对高危因素进行早期预防和及时处理是降低SAP病死率的关键。  相似文献   
1000.
BACKGROUND: Acute normovolaemic haemodilution (ANH) is an efficacious bloodconservation strategy aiming at avoiding allogeneic blood transfusion.ANH was shown to increase the potency of vecuronium, atracurium,and rocuronium. The aim of our study was to investigate whethercisatracurium potency is altered with ANH. METHODS: Using the Relaxometer mechanomyograph, we compared cisatracuriumdose–response relationship and time course of action in60 patients randomly allocated to the ANH or control groups.Patients in each group were randomly allocated to receive oneof three cisatracurium doses (30, 40, 50 µg kg–1)followed by a second supplemental dose to reach a total of 100 µg kg–1. RESULTS: ANH did not result in a significant shift in cisatracurium logdose–probit dose–response curve. There was no significantdifference in mean (95% confidence intervals) ED50, ED90, andED95 (effective doses required for 50, 90, and 95% first twitchdepression) between the ANH group [29.5 (27–32), 50.4(47.4–53.4), 58.7 (55.3–62) µg kg–1]and the control group [28.2 (25.3–31), 47.6 (44.9–50.3),55.3 (52.5–58.1) µg kg–1], whereasthere was no difference in mean (SD) Dur25 and Dur0.8 (timeuntil 25% first twitch and 0.8 train-of-four ratio recoveries)between the ANH group [40.8 (5.9), 64.7 (8.4) min] and the controlgroup [42.2 (7.6), 66.5 (10.7) min]. CONCLUSIONS: Our results demonstrated that unlike other previously reportedneuromuscular blocking drugs, ANH did not alter cisatracuriumpotency. Thus, cisatracurium would be the neuromuscular blockingdrug of choice in patients who undergo surgery with ANH, asno dose adjustments are required.  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