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   529998篇
  免费   27637篇
  国内免费   495篇
耳鼻咽喉   6681篇
儿科学   16921篇
妇产科学   12537篇
基础医学   92608篇
口腔科学   12347篇
临床医学   48495篇
内科学   95430篇
皮肤病学   11868篇
神经病学   34007篇
特种医学   19755篇
外国民族医学   53篇
外科学   78064篇
综合类   7610篇
现状与发展   2篇
一般理论   107篇
预防医学   38533篇
眼科学   11939篇
药学   41406篇
  1篇
中国医学   1126篇
肿瘤学   28640篇
  2021年   3892篇
  2018年   5731篇
  2017年   4126篇
  2016年   4869篇
  2015年   5360篇
  2014年   7114篇
  2013年   10498篇
  2012年   15572篇
  2011年   17389篇
  2010年   9956篇
  2009年   8821篇
  2008年   15711篇
  2007年   17443篇
  2006年   16939篇
  2005年   16260篇
  2004年   15880篇
  2003年   15263篇
  2002年   14782篇
  2001年   22428篇
  2000年   22970篇
  1999年   18919篇
  1998年   5232篇
  1997年   4364篇
  1996年   4397篇
  1995年   4124篇
  1992年   14413篇
  1991年   15817篇
  1990年   15949篇
  1989年   15625篇
  1988年   14308篇
  1987年   14198篇
  1986年   13168篇
  1985年   12686篇
  1984年   9394篇
  1983年   8000篇
  1982年   4177篇
  1979年   8937篇
  1978年   6382篇
  1977年   5149篇
  1976年   5504篇
  1975年   6613篇
  1974年   7419篇
  1973年   7158篇
  1972年   6597篇
  1971年   6309篇
  1970年   5887篇
  1969年   5467篇
  1968年   5161篇
  1967年   4621篇
  1966年   3963篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Play therapy     
  相似文献   
993.
994.

Background  

Lag screw cut-out failure following fixation of unstable intertrochanteric fractures in osteoporotic bone remains an unsolved challenge. This study tested if resistance to cut-out failure can be improved by using a dual lag screw implant in place of a single lag screw implant. Migration behavior and cut-out resistance of a single and a dual lag screw implant were comparatively evaluated in surrogate specimens using an established laboratory model of hip screw cut-out failure.  相似文献   
995.
Defects involving the distal leg and foot are frequently encountered following various aetiological factors. Paucity of local tissue causes surgeons to resort to the retrograde peninsular flap, the cross leg flap or the free flap. With specific knowledge of perforators, the fasciocutaneous flap from the calf area can be transferred to the defect in a single stage based on skeletonised distal perforators. The surgical anatomy, flap planning and procedure have been detailed. Nineteen patients were treated during the period 1995 to 2005. The perforators were identified preoperatively by audio Doppler. The flaps were marked and dissected proximal to the defect skeletonising the distal perforators under loupe magnification and transferred to the defect in a single stage. The donor site was skin grafted. Out of 19 cases, 16 flaps healed uneventfully, one flap necrosed completely and in two cases there was marginal necrosis. The cases were followed up for 2-10 years with an average of 6 years. With detailed knowledge of perforators one can safely reconstruct distal moderate-size defects of the lower limb in a single stage, thus having the benefits of free tissue transfer without resorting to microsurgery. This technique has proved to be an advancement in the reconstructive repertoire allowing flaps of non conventional dimensions to be perfused by skeletonised perforators.  相似文献   
996.
Transplant patients are at the risk for posttransplant lymphoproliferative disease (PTLD), a virally-driven malignancy. Induction with the depleting antibody preparations Thymoglobulin and OKT3 is associated with PTLD suggesting that the T-cell depletion increases PTLD risk. We therefore studied 59 560 kidney recipients from the Organ Procurement and Transplantation Network/United Network for Organ Sharing (OPTN/UNOS) database for a relationship between induction agent use and PTLD. Two agents with comparable T-cell depletional effects, alemtuzumab and Thymoglobulin, were compared to nondepletional induction agents or no induction. The overall incidence of PTLD was 0.46% and differed significantly by induction strategy (p < 0.01): without induction (0.43%), basiliximab (0.38%), daclizumab (0.33%), Thymoglobulin (0.67%) and alemtuzumab (0.37%). Thymoglobulin was associated with significantly increased PTLD risk (p = 0.0025), but alemtuzumab (p = 0.74), basiliximab (p = 0.33) and daclizumab, which trended toward a protective effect (p = 0.06), were not. Alemtuzumab and Thymoglobulin treated patients did not differ in any established parameter affecting PTLD risk although alemtuzumab is known to have a more pronounced B-cell depleting effect. Interestingly, maintenance therapy with an mTOR inhibitor was strongly associated with PTLD (0.71%, p < 0.0001). Thus, depletional induction is not an independent risk factor for PTLD. Rather, maintenance drug selection or perhaps the balance between B- and T-cell depletion may be more relevant determinants of PTLD risk.  相似文献   
997.
Diverticula arising from the mitral valve are very rare. They are usually detected by echocardiography as masses arising from the cardiac valves. We present a case of an incidental finding of a diverticulum arising from the mitral valve. This was initially detected by transesophageal echocardiography, and later confirmed by pathologic appearance. The case illustrates the unique findings on echocardiography that would help to differentiate diverticula from other valvular masses.  相似文献   
998.
The changes in spike activity of single neurons of the compact part of the substantia nigra, evoked by nucleus caudatus stimulation under conditions of long-term registration of the single and multiple, isolated and combined actions of GABA, GABA-amide, glutamine, and ethanolamine-O-sulfate (EOS) were studied in albino rats. Inhibition of poststimulus activity under GABA action was recorded and the inhibitory effect of GABA-amide was revealed. Primary excitatory and subsequent inhibitory effects of glutamine in combination with EOS were shown. The subsequent administration of bacterial melanin, synthesized by a mutant culture of Bacillus thuringiensis (BT-M) evoked a clear-cut and prolonged excitatory reaction during all the combined actions of GABA, GABA-amide, glutamine, and EOS. Preliminary administration of BT-M abolished the inhibitory poststimulus effects of GABA, GABA-amide, and EOS, as well as glutamine-induced excitation.  相似文献   
999.
BACKGROUND: Imatinib mesylate (IM), the first-line treatment of chronic myeloid leukaemia (CML), is a tyrosine kinase inhibitor that targets those proteins involved in BCR-ABL signal transduction in CML, c-kit (KIT) and platelet-derived growth-factor (PDGFR) receptor. The use of IM has been associated with cutaneous reactions. In the last 2 years numerous studies have focused the attention on hypopigmentations, depigmentations and photosensitivity developing after the initiation of IM therapy. OBJECTIVE: The aim of this study is to evaluate the effects of IM therapy on the skin pigmentation of five patients affected by CML. METHODS: Skin pigmentation measurements were performed with a Minolta CR-200 Chromameter. results: All the studied patients show the gradual lightening of the skin on unexposed areas over the treatment with IM. In particular, this explorative colorimetric study indicates the association between IM and skin depigmentation with a significant increase of luminance value (L*) (P = 0.001) and a significant decrease of the pigmentation value (b*) (P = 0.028). CONCLUSION: Even if we do not know the clinical significance of the skin depigmentation caused by IM, the regulatory role of KIT and its ligand stem cell factor in melanocyte development and survival seems to suggest an objective mechanism of action for IM in the pathogenesis of this cutaneous depigmentation.  相似文献   
1000.
BACKGROUND: At long-term follow up we cannot easily differentiate between patients who have undergone free transverse rectus abdominis musculocutaneous (TRAM) flap and deep inferior epigastric artery perforator (DIEP) flap breast reconstruction in terms of subjective functional limitations of daily activities. The aim of this study was to evaluate postoperative outcomes and long-term subjective functional deficit in patients following unilateral free TRAM compared with DIEP flap breast reconstruction. METHODS: Sixty consecutive patients who underwent unilateral autologous breast reconstruction were included in the study, 30 of whom had undergone a DIEP flap, and 30 a free TRAM flap. Surgical and postoperative outcome data were collected and a postal questionnaire was sent to each patient at least 6 months postoperatively consisting of a short functional assessment questionnaire and a Short Form 36 (SF-36) survey. RESULTS: We found no significant difference in postoperative outcomes or in the subjective ability to perform activities of daily living, including work, domestic activities, sports and hobbies, between patients who underwent TRAM flap breast reconstruction and those who underwent a DIEP flap, and no significant difference between the groups for scores on the physical functioning, role-physical, or bodily pain scales of the SF-36. CONCLUSION: We conclude that harvesting of the free TRAM flap results in no significant difference in postoperative outcomes or in the subjective ability to perform activities of daily living compared with the DIEP flap.  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