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   26787篇
  免费   1791篇
  国内免费   116篇
耳鼻咽喉   333篇
儿科学   561篇
妇产科学   501篇
基础医学   3914篇
口腔科学   396篇
临床医学   2475篇
内科学   6223篇
皮肤病学   472篇
神经病学   2904篇
特种医学   999篇
外国民族医学   3篇
外科学   4471篇
综合类   147篇
一般理论   6篇
预防医学   1394篇
眼科学   422篇
药学   1910篇
中国医学   95篇
肿瘤学   1468篇
  2023年   100篇
  2022年   194篇
  2021年   428篇
  2020年   260篇
  2019年   479篇
  2018年   564篇
  2017年   435篇
  2016年   486篇
  2015年   625篇
  2014年   809篇
  2013年   1095篇
  2012年   1670篇
  2011年   1763篇
  2010年   1118篇
  2009年   980篇
  2008年   1651篇
  2007年   1739篇
  2006年   1630篇
  2005年   1716篇
  2004年   1633篇
  2003年   1631篇
  2002年   1554篇
  2001年   439篇
  2000年   372篇
  1999年   429篇
  1998年   396篇
  1997年   342篇
  1996年   279篇
  1995年   294篇
  1994年   233篇
  1993年   242篇
  1992年   274篇
  1991年   239篇
  1990年   198篇
  1989年   214篇
  1988年   175篇
  1987年   191篇
  1986年   193篇
  1985年   145篇
  1984年   150篇
  1983年   144篇
  1982年   130篇
  1981年   105篇
  1980年   104篇
  1979年   104篇
  1978年   63篇
  1977年   83篇
  1975年   65篇
  1974年   52篇
  1973年   74篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Infection of the temperature-sensitive E. coli CRT 266 (dna Bts) with T3-phages at the temperature of 30°C and 35°C, respectively, induced T3-specific RNA synthesis with a maximum rate at 7 min (30°C) and 4.5 min (35°C) afte infection. At temperatures above 40°C no T3-induced RNA synthesis could be observed. Infection of E. coli CR 34–45 (dna B+) with T3 phages at 30°C, 35°C and at temperatures above 40°C, however, produced T3-specific RNA synthesis. The maximum of T3-induced RNA synthesis could be observed between 7 min and 3 min depending on the temperature during infection. The inability to form T3-specific RNA after infection of E. coli CRT 266 at nonpermissive temperatures may be a cause for the absence of the formation of T3 phages and lysis of the host cells.  相似文献   
993.
We report on the screening and development of haploidentical hematopoietic stem cell transplantation (HSCT) for adult patients with clinically aggressive sickle cell disease (SCD) at our institution. Of 50 adult SCD patients referred for HSCT between January 2014 and March 2017, 20% were denied by insurance. Of 41 patients initially screened, 10% lacked an available haploidentical donor, 29% had elevated donor-specific antibodies (DSAs), and 34% declined to proceed to HSCT. All 10 patients who were transplanted received peripheral blood stem cells. The initial 2 were conditioned with alemtuzumab/total body irradiation (TBI) 3?Gy followed by post-transplant cyclophosphamide and failed to engraft. The next 8 patients received the regimen developed at Johns Hopkins University with TBI 3?Gy. Granulocyte colony-stimulating factor was administered from day +12 in those with HbS < 30%. All 8 patients engrafted with a median time to neutrophil >.5 × 109/L of 22 days (range, 18 to 23). One patient subsequently lost the graft, and 7 (87.5%) maintained >95% donor cell chimerism at 1-year post-HSCT. Two patients developed acute graft-versus-host disease (GVHD) of at least grade II. One had chronic GVHD and died >1 year after HSCT of unknown causes. With a median follow-up of 16 months (range, 11 to 29), 7 patients (87.5%) are alive. Our findings suggest that limited insurance coverage, high rate of DSAs, and patient declining HSCT may limit the availability of haploidentical HSCT in adult SCD patients. The modified Hopkins regimen used here demonstrates high engraftment and low morbidity rates and should be tested in larger, multicenter, prospective clinical trials.  相似文献   
994.
995.
996.
This paper reports the cosegregation in a three generation pedigree of dominantly inherited cataract with an abnormally high level of serum ferritin. In this family, circulating L ferritin was raised in all subjects affected by cataract independently of iron overload. We suggest that a disorder of ferritin metabolism could be a new genetic disorder leading to lens opacity. Cataract-hyperferritaemia syndrome could also be a new contiguous gene syndrome involving the L ferritin gene and the gene coding for the lens membrane protein (MP19), which both map to the same region of chromosome 19q.  相似文献   
997.
Human keratinocytes (HK) generate nitric oxide (NO) and proinflammatory mediators following activation with either IgE/anti-IgE immune complexes or a combination of lipopolysaccharide (LPS) and interferon-γ (IFN-γ). Recently, interleukin-10 (IL-10) has been shown to down-regulate various inflammatory responses and to be secreted by lymphocytes and dendritic cells during skin inflammatory reactions. We show here that IL-10 down-regulates the production of tumor necrosis factor (TNF)-α and IL-6 by activated HK. Also, induction of inducible nitric oxide synthase (iNOS) expression in HK by IgE/anti-IgE or LPS/IFN-γ is significantly reduced by the addition of IL-10. This effect is dose dependent and correlates with reduction of iNOS mRNA production and enzyme level. Therefore, IL-10 down-regulates NO-mediated HK inflammatory responses and may thus participate in the regulation of the skin immune network.  相似文献   
998.
Follicular oocytes from Xenopus laevis contain K+ channels that are activated by members of the recently recognized class of vasorelaxants that includes the pinacidil derivative P1060. These channels are blocked by antidiabetic sulphonylureas such as glibenclamide. Opening of the glibenclamide-sensitive K+ channels with P1060 promotes follicular oocyte maturation. Whole-cell and single-channel patch-clamp configurations were used to monitor K+ channel activity in isolated follicular cells. In the presence of micromolar concentrations of intracellular Mg2+ ATP, P1060 activated a whole-cell K+ current that was blocked by glibenclamide. The P1060 response was depressed by millimolar concentrations of intracellular ATP and ATP[S]. Single-channel recordings identified two different types of K+ channel. These channels differed in their unitary conductances (19 pS and 150 pS), in their sensitivities to internal Ca2+, to charybdotoxin and to pinacidil and glibenclamide. Only the Ca2+-independent K+ channel (19 pS) was activated by the pinacidil derivative and blocked by glibenclamide. Opening of the 19-pS glibenclamide-sensitive K+ channel by P1060 critically required the presence of a low concentration of Mg2+ATP in the intracellular medium. The 19-pS K+ channel was opened by increasing intracellular cAMP. Similar effects were obtained by intracellular application of the catalytic subunit of protein kinase A in the presence of micromolar concentrations of Mg2+ATP. Both acetylcholine and the phorbol ester phorbol 12-myristate 13-acetate blocked the 19-pS K+ channel after it was activated by P1060.This work was supported by the Centre National de la Recherche Scientifique (CNRS) and the Fondation pour la Recherche Médicale (FRM)  相似文献   
999.
Parasitology Research - The tick Rhipicephalus microplus affects cattle health, with production loss in tropical and subtropical regions. Moreover, the use of commercial acaricides has been reduced...  相似文献   
1000.
OBJECTIVES : We have previously reported that 5-lipoxygenase-derived products, and particularly the cysteinyl leukotrienes (CysLTs), were involved in angiotensin II (Ang II)-induced contractions in isolated aortas from spontaneously hypertensive rats. DESIGN : The aim of this study was to assess the role of CysLTs in the vascular response to Ang II in an Ang II-dependent model of hypertension, the (mRen-2)27 transgenic rats (TGs). METHODS : Intact aortic rings from TG and normotensive Sprague-Dawley rats (SDs) were suspended in organ chambers for isometric tension development in response to Ang II. In addition, the release of CysLTs in response to Ang II (0.3 micromol/l) was measured by enzyme immunoassay. RESULTS : In isolated aortas from TG rats, pretreatment with the 5-lipoxygenase inhibitor (AA861, 10 micromol/l) or the CysLT1 receptor antagonist (MK571, 1 micromol/l) significantly (P < 0.05) reduced Ang II-induced contractions by 52 and 42%, respectively. In addition, Ang II induced a 2.6-fold increase in CysLT release (pg/mg dry weight tissue: 58.3 +/- 17.9 (Ang II, n = 7) versus 22.5 +/- 5.9 (basal, n = 7) P < 0.05), which was inhibited by the AT1 receptor antagonist losartan (1 micromol/l). In contrast, in aortas from SD rats, pretreatment with AA861 or MK571 did not alter Ang II-induced contraction and CysLT production remained unchanged after exposure to Ang II. CONCLUSION : These data suggest that CysLTs are involved in the contractile responses to Ang II in isolated aortas from TG but not from SD rats.  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