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   214185篇
  免费   13508篇
  国内免费   593篇
耳鼻咽喉   2578篇
儿科学   6943篇
妇产科学   4719篇
基础医学   29358篇
口腔科学   8029篇
临床医学   17279篇
内科学   47377篇
皮肤病学   5171篇
神经病学   19480篇
特种医学   6343篇
外国民族医学   26篇
外科学   24948篇
综合类   1760篇
现状与发展   1篇
一般理论   118篇
预防医学   23237篇
眼科学   3717篇
药学   13136篇
中国医学   771篇
肿瘤学   13295篇
  2023年   1497篇
  2022年   2955篇
  2021年   5614篇
  2020年   3629篇
  2019年   5074篇
  2018年   6726篇
  2017年   4908篇
  2016年   4792篇
  2015年   5501篇
  2014年   7306篇
  2013年   9304篇
  2012年   14604篇
  2011年   15077篇
  2010年   7608篇
  2009年   6791篇
  2008年   11407篇
  2007年   11982篇
  2006年   11198篇
  2005年   11292篇
  2004年   10510篇
  2003年   9549篇
  2002年   7324篇
  2001年   5128篇
  2000年   5078篇
  1999年   4542篇
  1998年   1878篇
  1997年   1533篇
  1996年   1475篇
  1995年   1246篇
  1994年   1190篇
  1993年   1088篇
  1992年   2715篇
  1991年   2620篇
  1990年   2387篇
  1989年   2385篇
  1988年   2150篇
  1987年   1989篇
  1986年   1866篇
  1985年   1782篇
  1984年   1298篇
  1983年   1050篇
  1982年   598篇
  1981年   553篇
  1980年   520篇
  1979年   936篇
  1978年   617篇
  1977年   494篇
  1975年   551篇
  1974年   543篇
  1973年   548篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
83.
84.
85.

Objective

Hypertonic saline (HTS) has potent immune and vascular effects. We assessed recipient pretreatment with HTS on allograft function in a porcine model of heart transplantation and hypothesized that HTS infusion would limit endothelial and left ventricular (LV) dysfunction following transplantation.

Methods

Heart transplants were performed after 6 hours of cold ischemic storage. Recipient pigs were randomized to treatment with or without HTS (7.5% NaCl) before cardiopulmonary bypass (CPB). Using a myograft apparatus, coronary artery endothelial-dependent (Edep) and -independent (Eind) relaxation was assessed. LV performance was determined using pressure-volume loop analysis. Pulmonary interleukin (IL)-2, IL-6, and tumor necrosis factor (TNF)-α expression was measured.

Results

Weaning from CPB and LV performance after transplantation were improved in HTS-treated animals. Successful weaning from CPB was greater in the HTS-treated hearts (8 of 8 vs 2 of 8; P < .05). Mean LV functional recovery was improved in the HTS-treated animals, as assessed by preload recruitable stroke work (65 ± 10% vs 27 ± 10%; P < .001) and end-systolic elastance (55 ± 7% vs 37 ± 4%; P < .001). Treatment with HTS resulted in improved Edep (mean maximum elastance [Emax], 56 ± 5% vs 37 ± 7%; P < .001) and Eind (mean Emax%, 77 ± 6% vs 52 ± 4%; P < .001) vasorelaxation compared with control. Pulmonary expression of IL-2, IL-6, and TNF-α increased following transplantation, whereas HTS therapy attenuated IL production (P < .001). Transplantation increased plasma TNF-α levels and LV TNF-α expression, whereas HTS prevented this up-regulation (P < .001).

Conclusions

Recipient HTS pretreatment preserves allograft vasomotor and LV function, and HTS therapy limits CPB-induced injury. HTS may be a novel recipient intervention to prevent graft dysfunction.  相似文献   
86.
87.
  1. The metabolism of the pyrethroids deltamethrin (DLM), cis-permethrin (CPM) and trans-permethrin (TPM) was studied in human expressed cytochrome P450 (CYP) and carboxylesterase (CES) enzymes.

  2. DLM, CPM and TPM were metabolised by human CYP2B6 and CYP2C19, with the highest apparent intrinsic clearance (CLint) values for pyrethroid metabolism being observed with CYP2C19. Other CYP enzymes contributing to the metabolism of one or more of the three pyrethroids were CYP1A2, CYP2C8, CYP2C9*1, CYP2D6*1, CYP3A4 and CYP3A5. None of the pyrethroids were metabolised by CYP2A6, CYP2E1, CYP3A7 or CYP4A11.

  3. DLM, CPM and TPM were metabolised by both human CES1 and CES2 enzymes.

  4. Apparent CLint values for pyrethroid metabolism by CYP and CES enzymes were scaled to per gram of adult human liver using abundance values for microsomal CYP enzymes and for CES enzymes in liver microsomes and cytosol. TPM had the highest and CPM the lowest apparent CLint values for total metabolism (CYP and CES enzymes) per gram of adult human liver.

  5. Due to their higher abundance, all three pyrethroids were extensively metabolised by CES enzymes in adult human liver, with CYP enzymes only accounting for 2%, 10% and 1% of total metabolism for DLM, CPM and TPM, respectively.

  相似文献   
88.
Batrachochytrium dendrobatidis is a fungal pathogen in the phylum Chytridiomycota that causes the skin disease chytridiomycosis. Chytridiomycosis is considered an emerging infectious disease linked to worldwide amphibian declines and extinctions. Although amphibians have well-developed immune defenses, clearance of this pathogen from the skin is often impaired. Previously, we showed that the adaptive immune system is involved in the control of the pathogen, but B. dendrobatidis releases factors that inhibit in vitro and in vivo lymphocyte responses and induce lymphocyte apoptosis. Little is known about the nature of the inhibitory factors released by this fungus. Here, we describe the isolation and characterization of three fungal metabolites produced by B. dendrobatidis but not by the closely related nonpathogenic chytrid Homolaphlyctis polyrhiza. These metabolites are methylthioadenosine (MTA), tryptophan, and an oxidized product of tryptophan, kynurenine (Kyn). Independently, both MTA and Kyn inhibit the survival and proliferation of amphibian lymphocytes and the Jurkat human T cell leukemia cell line. However, working together, they become effective at much lower concentrations. We hypothesize that B. dendrobatidis can adapt its metabolism to release products that alter the local environment in the skin to inhibit immunity and enhance the survival of the pathogen.  相似文献   
89.
90.
Annals of Hematology - This study assessed treatment patterns and healthcare resource utilization (HRU) of patients with severe aplastic anemia (SAA) with insufficient response to immunosuppressive...  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