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   8331篇
  免费   768篇
  国内免费   431篇
耳鼻咽喉   79篇
儿科学   107篇
妇产科学   110篇
基础医学   959篇
口腔科学   207篇
临床医学   1002篇
内科学   1442篇
皮肤病学   270篇
神经病学   533篇
特种医学   298篇
外国民族医学   3篇
外科学   941篇
综合类   1029篇
现状与发展   1篇
一般理论   1篇
预防医学   540篇
眼科学   171篇
药学   838篇
  4篇
中国医学   343篇
肿瘤学   652篇
  2024年   16篇
  2023年   111篇
  2022年   256篇
  2021年   357篇
  2020年   243篇
  2019年   276篇
  2018年   315篇
  2017年   261篇
  2016年   264篇
  2015年   360篇
  2014年   399篇
  2013年   441篇
  2012年   548篇
  2011年   610篇
  2010年   370篇
  2009年   276篇
  2008年   433篇
  2007年   460篇
  2006年   483篇
  2005年   438篇
  2004年   277篇
  2003年   294篇
  2002年   211篇
  2001年   185篇
  2000年   182篇
  1999年   196篇
  1998年   146篇
  1997年   125篇
  1996年   93篇
  1995年   89篇
  1994年   79篇
  1993年   43篇
  1992年   100篇
  1991年   64篇
  1990年   71篇
  1989年   41篇
  1988年   59篇
  1987年   54篇
  1986年   43篇
  1985年   38篇
  1984年   26篇
  1983年   18篇
  1982年   16篇
  1981年   24篇
  1980年   12篇
  1979年   21篇
  1977年   11篇
  1976年   19篇
  1973年   9篇
  1969年   7篇
排序方式: 共有9530条查询结果,搜索用时 11 毫秒
51.
52.
Tuberculosis(TB)isthemostcommoncauseofdeathininfectiousdiseases; itisestimatedthatapproximately2millionpeopleperyeardieofTB ThepresentavailableTBvaccineisaliveattenuatedstrain,MycobacteriumbovisBacillusCalmetteGuérin (BCG) However, ithasbeenshownthatBCGhasvariableprotectiveefficacy, rangingfrom 0 to85% indifferentclinicalexperiments 1 Therefore, anewTBvaccineisurgentlyneeded Manytrialshavebeendonetodevelopthesecond generationTBvaccinesinrecentyears; candidatesincludeavirulent, auxotro…  相似文献   
53.
54.
Knee dislocation: treatment of high-velocity knee dislocation   总被引:9,自引:0,他引:9  
Yeh WL  Tu YK  Su JY  Hsu RW 《The Journal of trauma》1999,46(4):693-701
BACKGROUND: We report the outcomes of patients treated with a new arthroscopic treatment modality for knee dislocation after high-velocity trauma. METHODS: Twenty-three patients (12 men, 11 women; 25 knees) with traumatic knee dislocation were treated with this technique. Under arthroscopy with gravity inflow irrigation, the ruptured posterior cruciate ligament was reconstructed with a patellar bone-tendon-bone graft, and the anterior cruciate ligament was debrided subacutely. The collateral ligament, meniscus, and capsules were repaired through additional incisions. RESULTS: The average interval between injury and surgery was 11.1+/-5 days (range, 5 to 25 days). After a mean follow-up period of 27.2+/-7.86 months, the mean extension was 1+/-2 degrees and the average flexion was 129.6+/-4.91 degrees. The mean Lysholm score was 84. There were no major complications. CONCLUSION: Arthroscopic posterior cruciate ligament reconstruction seems to be an effective treatment for traumatic knee dislocation.  相似文献   
55.
探讨手术创伤后围术期红细胞丙酮酸激酶活性改变与糖代谢障碍 (或称“外科性糖尿病”)的关系。随机选择中等度手术创伤如上腹部胆囊切除或胃大部切除手术病人 17例 ,ASAⅠ~Ⅱ级 ,观察普鲁卡因静脉复合麻醉 (IPBA)下上腹部手术对围麻醉手术期红细胞(RBC)丙酮酸激酶 (PK)活性及其相关重要调理因子 ,如RBC内ATP、ADP、Pi、Mg2 + ,以及血浆葡萄糖、血清胰岛素的影响。结果显示 ,PK在手术结束后 10min较麻醉前明显下降 (P<0 0 1) ,术后 2 4h仍无回升趋势。RBC Pi的变化与PK无相关性 (r=- 0 0 4 1,P >0 0 5 ) ,ATP/ADP比值的变化与PK呈正相关趋势(r=0 6 80 ,P <0 0 1) ,RBC Mg2 + 的变化与PK呈明显负相关 (r=- 0 817,P <0 0 5 ) ,Glu/Ins的变化与PK呈负相关趋势 (r=- 0 6 97,P <0 1)。研究表明 ,IPBA和上腹部手术创伤可直接或(和 )间接引起细胞内PK活性下降和糖酵解通路的障碍 ,导致细胞对葡萄糖、Pi的利用和ATP的合成障碍 ;围术期糖酵解反应的抑制可能是应激性糖代谢障碍的重要机制之一 ,在手术后期和术后表现尤为明显  相似文献   
56.
Effects of Stamm gastrostomy on gastric emptying rate in rats   总被引:1,自引:0,他引:1  
AIM: Although frequency of gastroesophageal reflux (GER) increases after gastrostomy, the role of gastric emptying in GER has not been evaluated. In this study, we examined the effects of Stamm gastrostomy on gastric emptying rate in rats and whether Stamm gastrostomy induces GER or not. METHODS: Sprague-Dawley rats were divided into three groups. Stamm gastrostomy was done in the first group (SG). Sham operation was carried out in group 2 and the 3rd group served as control. Gastric emptying was assessed using both liquid and solid meals in each group at postoperative 14th day. For solid meal emptying, after fasting of 16 h, the rats were fed for 3 h and gastric emptying rate was measured at the fifth hour. Methylcellulose was used for emptying of liquids and it was given after the animals were fasted for 16 h and gastric emptying rate was measured 30 min later. Histological evaluation for GER was performed in all groups. RESULTS: GER was observed pathophysiologically in 5 of the 7 rats in SG group. Gastric emptying rates of liquid and solid meals were found to be similar in control, SG or sham groups. CONCLUSION: Surgical gastrostomy does not affect the gastric emptying of solid and liquid meals in rats. Other mechanisms should be considered in the development of GER observed following gastrostomy.  相似文献   
57.
Sclerostin, the Wnt signaling antagonist encoded by the Sost gene, is secreted by osteocytes and inhibits bone formation by osteoblasts. Mechanical stimulation reduces sclerostin expression, suggesting that osteocytes might coordinate the osteogenic response to mechanical force by locally unleashing Wnt signaling. To investigate whether sclerostin downregulation is a pre-requisite for load-induced bone formation, we conducted experiments in transgenic mice (TG) engineered to maintain high levels of SOST expression during mechanical loading. This was accomplished by introducing a human SOST transgene driven by the 8 kb fragment of the DMP1 promoter that also provided osteocyte specificity of the transgene. Right ulnae were subjected to in vivo cyclic axial loading at equivalent strains for 1 min/day at 2 Hz; left ulnae served as internal controls. Endogenous murine Sost mRNA expression measured 24 h after 1 loading bout was decreased by about 50% in TG and wild type (WT) littermates. In contrast, human SOST, only expressed in TG mice, remained high after loading. Mice were loaded on 3 consecutive days and bone formation was quantified 16 days after initiation of loading. Periosteal bone formation in control ulnae was similar in WT and TG mice. Loading induced the expected strain-dependent increase in bone formation in WT mice, resulting from increases in both mineralizing surface (MS/BS) and mineral apposition rate (MAR). In contrast, load-induced bone formation was reduced by 70-85% in TG mice, due to lower MS/BS and complete inhibition of MAR. Moreover, Wnt target gene expression induced by loading in WT mice was absent in TG mice. Thus, downregulation of Sost/sclerostin in osteocytes is an obligatory step in the mechanotransduction cascade that activates Wnt signaling and directs osteogenesis to where bone is structurally needed.  相似文献   
58.
连续性肾脏替代治疗中滤器后加热法对患者体温的影响   总被引:1,自引:0,他引:1  
目的探讨连续性肾脏替代治疗(CRRT)中滤器后加热法对患者体温的影响。方法将60例行CRRT治疗的患者随机分为对照组和观察组各30例,对照组按常规将加温装置连接到置换液的管路上,观察组将加温装置连接到滤器后静脉端血液回输管路上。两组均于CRRT治疗开始3h、6h、12h时测量患者体温及深静脉置管的动、静脉端的血液温度;比较两组治疗前后溶血反应相关检验结果。结果在CRRT治疗不同时段,两组深静脉置管的动、静脉端的血液温度比较,干预主效应均P<0.05;治疗12h时观察组低体温发生率显著低于对照组(P<0.05)。两组治疗前后溶血反应相关检验结果比较,差异无统计学意义(均P>0.05)。结论滤器后加热血液回输管路的方式可安全有效地补充CRRT治疗中循环热量,降低CRRT治疗中低体温发生率。  相似文献   
59.
Wu JC  Huang WC  Tsai TY  Fay LY  Ko CC  Tu TH  Wu CL  Cheng H 《Spine》2012,37(20):E1251-E1259
STUDY DESIGN.: Retrospective cohort study. OBJECTIVE.: To investigate the differences between single- and multilevel degenerative disc diseases (DDDs) treated with cervical arthroplasty. SUMMARY OF BACKGROUND DATA.: The US Food and Drug Administration clinical trials compared arthroplasty with anterior cervical discectomy and fusion for single-level DDD. However, cervical arthroplasty for multilevel DDD is rarely addressed in the literature. METHODS.: A total of 102 consecutive patients who underwent Bryan arthroplasty were divided into either a single- or multilevel group. Clinical outcomes were measured by the visual analogue scale (VAS) of neck and arm, and by the neck disability index with a minimum follow-up of 25 months. Every patient had radiographical evaluations, and computed tomography. RESULTS.: Eighty-six patients (84.3%) completed the follow-up with a mean time of 38.3 ± 8.7 months. Postoperatively, there were significant improvements in clinical outcomes (i.e., VAS neck, VAS arm, and neck disability index) at each time point of evaluation (i.e., 3-, 6-, 12-, and 24 mo postoperation). The sex composition and clinical outcome improvements between the single- and multilevel groups were not significantly different. The multilevel group was older (51.3 ± 8.6 vs. 46.3 ± 11.2 yr; P = 0.02), had more intraoperative blood loss (218.0 ± 182.4 vs. 102.8 ± 79.2 mL; P = 0.001), and demonstrated a higher rate of heterotopic ossification (HO) than the single-level group (66.0% vs. 25.0%; P < 0.001). The majority (97.7%) of the artificial discs in this series remained mobile despite HO. CONCLUSION.: Clinical outcomes of cervical arthroplasty in multilevel spondylosis are similar to single-level outcomes. However, the significantly higher rate of HO found in multilevel arthroplasty and its long-term effect warrant further investigation.  相似文献   
60.
To realize the therapeutic potential of mesenchymal stem cells (MSCs), we aimed to develop a method for isolating and expanding New Zealand rabbit MSCs in a great scale. Rabbit MSCs expanded under hypoxic and normoxic conditions were compared in terms of replication capacity, differentiation potential, and the capacity for allogeneic transplantation in a calvarial defect model. The cells from all tested rabbits were expanded more rapidly when plated at low‐density under hypoxic conditions compared to under normoxic conditions. Moreover, cells expanded under hypoxic conditions increased in the potential of osteoblastic, adipocytic, and chondrocytic differentiation. More importantly, radiographic analysis and micro‐CT measurement of bone volume revealed the hypoxic cells when transplanted in the calvarial defects of another rabbit increased in the ability to repair bone defect compared to the normoxic cells. Six weeks after allogeneic transplantation of hypoxic MSCs, histological analysis revealed a callus spanned the length of the defect, and several bone tissues spotted in the implant. At 12 weeks, new bone had formed throughout the implant. Using BrdU labeling to track the transplanted cells, the hypoxic cells were more detected in the newly formed bone compared to the normoxic cells. For defects treated with allogeneic MSCs, no adverse host response could be detected at any time‐point. In conclusion, we have developed a robust method for isolation and expansion of rabbit MSCs by combining low‐density with hypoxic culture, which can be applied for the design of clinical trials in allogeneic transplantation of MSCs for bone healing. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1213–1220, 2012  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