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   1144篇
  免费   56篇
  国内免费   56篇
耳鼻咽喉   1篇
儿科学   68篇
妇产科学   8篇
基础医学   128篇
口腔科学   21篇
临床医学   143篇
内科学   262篇
皮肤病学   51篇
神经病学   48篇
特种医学   298篇
外科学   44篇
综合类   23篇
预防医学   39篇
眼科学   6篇
药学   59篇
中国医学   2篇
肿瘤学   55篇
  2023年   4篇
  2022年   3篇
  2021年   9篇
  2020年   9篇
  2019年   8篇
  2018年   17篇
  2017年   3篇
  2016年   7篇
  2015年   13篇
  2014年   15篇
  2013年   40篇
  2012年   22篇
  2011年   14篇
  2010年   35篇
  2009年   55篇
  2008年   27篇
  2007年   55篇
  2006年   22篇
  2005年   22篇
  2004年   12篇
  2003年   13篇
  2002年   14篇
  2001年   14篇
  2000年   14篇
  1999年   20篇
  1998年   71篇
  1997年   80篇
  1996年   101篇
  1995年   61篇
  1994年   60篇
  1993年   52篇
  1992年   17篇
  1991年   15篇
  1990年   20篇
  1989年   37篇
  1988年   38篇
  1987年   35篇
  1986年   44篇
  1985年   40篇
  1984年   10篇
  1983年   15篇
  1982年   13篇
  1981年   9篇
  1980年   11篇
  1979年   8篇
  1978年   12篇
  1977年   9篇
  1976年   13篇
  1975年   13篇
  1973年   2篇
排序方式: 共有1256条查询结果,搜索用时 15 毫秒
91.
DiSantis  DJ; Cramer  MS; Scatarige  JC 《Radiology》1987,164(2):363-364
To test the feasibility of teleradiology for use with excretory urograms obtained in the emergency department in cases for suspected renal colic, radiographs from 43 patients were digitized, transmitted via standard phone lines, and viewed on a video monitor 2 miles distant. Diagnostic interpretations of the video image and the original radiograph were reviewed for degree of concordance. The video and film images of the 27 examinations showing obstruction were interpreted with 100% correlation. Agreement as to the site of obstruction was present in 93% of cases. Only two-thirds of renal and ureteral calculi seen on the radiographs were discerned on the video images, however. Teleradiology proved as useful for ongoing monitoring and modification of these examinations as for initial interpretation.  相似文献   
92.
93.
94.
95.
Arteriovenous malformations of the extremities: MR imaging   总被引:3,自引:0,他引:3  
Cohen  JM; Weinreb  JC; Redman  HC 《Radiology》1986,158(2):475-479
Eight patients with angiographically proved arteriovenous malformations (AVMs) of the extremities (seven congenital, one posttraumatic) were evaluated with magnetic resonance (MR) imaging using a 0.35-T superconducting system and spin-echo pulse sequences. Congenital AVMs appeared as accumulations of dilated tortuous blood vessels infiltrating the involved muscles. A posttraumatic acquired AVM of the shoulder consisted of a large feeding artery associated with a pseudoaneurysm and a soft-tissue mass. MR imaging allowed precise anatomic localization and provided details concerning the size and extent of the AVMs. The relationship of AVMs to specific muscle groups, bones, and vascular structures could be accurately determined. Although major feeding and draining vessels were identified, the exact arteries and veins supplying and draining the AVM could not be ascertained. Images obtained in the transverse plane consistently yielded the most useful information. MR imaging and angiography may be complementary techniques in the initial evaluation, follow-up, and treatment planning of AVMs of the extremities.  相似文献   
96.
Inhibition of human lymphocyte reactivity by plasma fibronectin in vitro   总被引:1,自引:0,他引:1  
The effect of purified human plasma fibronectin (FN) on the reactivity of human lymphocyte-rich mononuclear cells to mitogens and allogeneic cell interactions was studied. Concentrations of FN from 25 to 100 micrograms per 250 microL of culture consistently depressed phytohemagglutinin (PHA) responses. To exert an inhibitory effect, FN must be present within 20 hours after the addition of PHA to cells, and, therefore, it appears to interfere with early events in the transformation process. Increasing the concentration of PHA failed to reduce the inhibitory effect of FN, which suggests that the depressed response was not the result of FN-PHA complex formation, which would reduce the amount of mitogen available for stimulation. This possibility was supported by the finding that FN also inhibited the mixed lymphocyte response (MLR), in a reaction that was not dependent on the activity of soluble antigen or mitogen. In contrast, the stimulation of lymphocytes to undergo transformation that is induced by the nonlectin mitogen, sodium periodate, was unaffected by FN. Periodate-treated cells are, however, already stimulated to undergo transformation, prior to their exposure to FN. FN did not interfere with the activity of interleukin-2, nor did it indirectly regulate lymphocyte responses by modifying the production and/or effect of humoral regulatory factors released from the adherent accessory cells (macrophages). These studies show that FN is a potent immunosuppressive agent in vitro.  相似文献   
97.
Two fibronectin (FN)-containing blood products, human peripheral blood plasma and cryoprecipitate, were examined for their effect on mitogen-induced lymphocyte transformation in vitro. Responses of human peripheral blood lymphocytes to phytohemagglutinin (PHA) were depressed in the presence of a plasma concentration above that required for maximum DNA synthesis, and this concentration must be present in cultures prior to lymphocyte activation. The removal from the plasma of heparin-induced cryoprecipitate, a complex consisting of FN, heparin, and fibrinogen, resulted in a significant reduction in the inhibitory effect of the plasma on the PHA response. Plasma specifically depleted of FN by affinity chromatography on gelatin-agarose beads was 32 percent less inhibitory to the PHA-induced stimulation of cells than untreated plasma; the remaining inhibitory activity in the FN-depleted plasma samples was attributed to the presence of other normal immunosuppressive factors. The inhibitory capacity of FN in plasma was similar to that obtained with purified FN alone, which indicates that, unlike that of other known plasma inhibitors, the immunosuppressive activity of FN was not altered by the presence of other components of plasma. Cryoprecipitate used in the treatment of hemophilia contains high levels of FN, and, as anticipated, PHA-induced lymphocyte transformation was markedly depressed in the presence of solubilized cryoprecipitate. The contribution of FN to the T-cell abnormalities in patients chronically receiving cryoprecipitate and/or factor VIII concentrates derived from cryoprecipitate warrants further investigation.  相似文献   
98.
个性化颅骨成形术中植入材料类型与颅骨缺损面积的关系   总被引:2,自引:0,他引:2  
目的:分析个性化颅骨成形术中,植入材料类型与颅骨缺损面积的关系。 方法:选择解放军总医院第二附属医院神经外科2002-03/2005-01和河北省三河市医院神经外科2003-09/2005-04收治的资料齐全的计算机辅助设计颅骨成形术患者75例,分为嵌入性材料(骨水泥、硅橡胶)组40例,根据颅骨缺损面积又分为大面积(≥36cm2)组17例和小面积(〈36cm2)组23例;覆盖性材料(钛网)组35例,大面积组14例和小面积组21例。采用头颅CT超薄扫描(层厚1.5mm),三维重建,模拟缺损颅骨补片,应用激光快速成形技术,制作缺损颅骨及颅骨补片模型,患者认可后,根据患者的病情应用硅橡胶、骨水泥、钛网作为植入材料,进行手术植入。术后1周观察并发症:头痛、积液、松动。 结果:75例患者的补片与颅骨完整适配,塑形满意,术中无需修整,平均手术时间45min,83%(63/75)患者感到基本或完全恢复了原有容貌。手术并发症:嵌入性材料组头痛4例,积液10例,松动2例,共16例,其中大面积组13例,小面积组3例;覆盖性材料组头痛1例,积液2例,松动0例,共3例次,其中大面积组2例,小面积组1例。应用精确概率分析,两材料组之间手术并发症差异显著,两材料组颅骨缺损面积之间手术并发症差异显著,嵌入性材料大面积组与覆盖性材料大面积组之间手术并发症差异显著,嵌入性材料小面积组与覆盖性材料小面积组之间手术并发症无显著性差异。 结论:个性化设计的颅骨修补材料,能够最大限度的恢复患者外形,缩短手术时间,大面积的颅骨缺损应用钛网修补,小面积的应用钛网和嵌入性材料修补。根据患者颅骨缺损面积,选择不同植入材料,可以提高手术疗效,减少术后并发症。  相似文献   
99.
IntroductionDaily and event‐driven PrEP are both efficacious in reducing the risk for HIV infection. However, the practice of event‐driven PrEP (edPrEP) is less well studied, in particular when provided as an alternative to daily PrEP. We studied regimen preferences and switches, and sexually transmitted infection (STI) incidence.MethodsWe analysed pooled data from two prospective cohort studies among MSM: Be‐PrEP‐ared, Belgium and AMPrEP, the Netherlands. In both projects, participants could choose between daily and edPrEP at three‐monthly study visits, when they were also screened for sexually transmitted infections including hepatitis C (HCV). We assessed the proportion choosing each regimen, and the determinants of choosing edPrEP at baseline. Additionally, we compared the incidence rates (IRs) of HCV, syphilis and chlamydia or gonorrhoea between regimens using Poisson regression. The study period was from 3 August 2015 until 24 September 2018.Results and discussionWe included 571 MSM, of whom 148 (25.9%) chose edPrEP at baseline. 31.7% of participants switched regimen at least once. After 28 months, 23.5% used edPrEP. Older participants (adjusted odds ratio (aOR) = 1.38 per 10 years, 95% confidence interval (CI) = 1.15 to 1.64) and those unemployed (aOR = 1.68, 95% CI = 1.03 to 1.75) were more likely to initially choose edPrEP. IR of HCV and syphilis did not differ between regimens, but the IR of chlamydia/gonorrhoea was higher among daily users (adjusted incidence rate ratio = 1.61, 95% CI = 1.35 to 1.94).ConclusionsA quarter of participants chose edPrEP at baseline and at 28 months this proportion was similar. Although the IR of HCV and syphilis were similar in the two regimens, the lower incidence of chlamydia and gonorrhoea among edPrEP users may suggest that less frequent STI testing of this group could be considered.  相似文献   
100.
In this issue, BJP is proud to publish an Endothelium Themed Section to celebrate the life of Robert F. Furchgott, who died on May 19th 2009. It is 30 years since he discovered endothelium-derived relaxant factor and a decade since he was awarded the Nobel Prize for this work. His discovery has led to an array of new therapeutic targets. The themed section includes three reviews on the pathophysiology of the endothelium and the drug targets that this presents, four research papers and three commentaries on research.This themed section also forms the nucleus of an online Virtual Issue that collects in one place further reviews and research papers on the topic of the ‘Endothelium’ that BJP and our sister journal BJCP have published in the past year, and that should help researchers and students to find the latest work in this field.To view the entire Endothelium Themed Section and the Endothelium Virtual Issue, please visit: http://www3.interscience.wiley.com/journal/121548564/issueyear?year=2009British Journal of Pharmacology (2009) 157, 491–493; doi:10.1111/j.1476-5381.2009.00366.xThis article is part of a themed section on Endothelium in Pharmacology. For a list of all articles in this section see the end of this paper, or visit: http://www3.interscience.wiley.com/journal/121548564/issueyear?year=2009Thirty years ago Robert F Furchgott found that a substance was released from vascular endothelium that caused relaxation of the smooth muscle in the vascular wall (Furchgott and Zawadzki, 1980), a discovery for which, a decade ago, he was awarded the Nobel Prize (Furchgott, 1999). This remarkable finding was, from my recollection anyway, the most exciting aspect of the second Symposium on Mechanisms of Vasodilatation, held at Wilrijk, Belgium in July 1980 (Vanhoutte and Leusen, 1981) and has been, one suspects, a major part of the reason that this series is now celebrating its 10th occurrence at Matsushima, Miyagi, Japan, in June 2009 (it is planned to publish work arising from this event in Circulation Journal).Thirty years on, the endothelium continues to yield information on pathophysiological mechanisms that provides many therapeutic targets for drug discovery and new explanations for drug action. A special Endothelium Themed Section in this issue of BJP collates three new reviews on the pathophysiology of the endothelium and the drug targets that this presents (Esposito and Cuzzocrea, 2009; Grgic et al., 2009; Versari et al., 2009), four research papers (de Andrade et al., 2009; Andrews et al., 2009; McKenzie et al., 2009; Orie et al., 2009) and three commentaries on research papers that discuss the significance and draw out controversies from their new findings (Martin, 2009, commenting on Andrews et al., 2009; Tammaro, 2009, commenting on Orie et al., 2009; Miller and Wadsworth, 2009, commenting on Wenzl et al., 2009 that was published in an earlier issue).These Endothelium reviews and two others already published (Félétou, 2009; Félétou et al., 2009) follow up symposia held at the Meeting of the Federation of European Pharmacological Societies (EPHAR) in Manchester, UK, in July 2008, and show the continuing importance of this field. To reflect this and provide access to our extensive portfolio of endothelial papers, we have collated this section with other recent reviews, commentaries and original articles from BJP and from our sister journal BJCP, in a Virtual Issue on Endothelium, available at: http://www3.interscience.wiley.com/journal/121548564/issueyear?year=2009 (see http://www3.interscience.wiley.com/journal/121548564/issueyear?year=2009)
Open in a separate windowThemed Section: Endothelium in PharmacologyEndothelium in pharmacology: 30 years on: J. C. McGrathRole of nitroso radicals as drug targets in circulatory shock: E. Esposito & S. CuzzocreaEndothelial Ca2+-activated K+ channels in normal and impaired EDHF–dilator responses – relevance to cardiovascular pathologies and drug discovery: I. Grgic, B. P. Kaistha, J. Hoyer & R. KöhlerEndothelium-dependent contractions and endothelial dysfunction in human hypertension: D. Versari, E. Daghini, A. Virdis, L. Ghiadoni & S. TaddeiNitroxyl anion – the universal signalling partner of endogenously produced nitric oxide?: W. MartinA role for nitroxyl (HNO) as an endothelium-derived relaxing and hyperpolarizing factor in resistance arteries: K. L. Andrews, J. C. Irvine, M. Tare, J. Apostolopoulos, J. L. Favaloro, C. R. Triggle & B. K. Kemp-HarperVascular KATP channels: dephosphorylation and deactivation: P. TammaroCa2+/calcineurin regulation of cloned vascular KATP channels: crosstalk with the protein kinase A pathway: N. N. Orie, A. M. Thomas, B. A. Perrino, A. Tinker & L. H. ClappUnderstanding organic nitrates – a vein hope?: M. R. Miller & R. M. WadsworthIncreased endothelin-1 reactivity and endothelial dysfunction in carotid arteries from rats with hyperhomocysteinemia: C. R. de Andrade, P. F. Leite, A. C. Montezano, D. A. Casolari, A. Yogi, R. C. Tostes, R. Haddad, M. N. Eberlin, F. R. M. Laurindo, H. P. de Souza, F. M. A. Corrêa & A. M. de OliveiraMechanisms of U46619-induced contraction of rat pulmonary arteries in the presence and absence of the endothelium: C. McKenzie, A. MacDonald & A. M. ShawThis issue is available online at http://www3.interscience.wiley.com/journal/121548564/issueyear?year=2009  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