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   787篇
  免费   47篇
  国内免费   4篇
耳鼻咽喉   2篇
儿科学   43篇
妇产科学   13篇
基础医学   123篇
口腔科学   28篇
临床医学   63篇
内科学   138篇
皮肤病学   16篇
神经病学   21篇
特种医学   144篇
外国民族医学   1篇
外科学   39篇
综合类   50篇
预防医学   53篇
眼科学   26篇
药学   36篇
中国医学   4篇
肿瘤学   38篇
  2021年   8篇
  2020年   7篇
  2019年   5篇
  2018年   13篇
  2017年   11篇
  2016年   14篇
  2015年   13篇
  2014年   21篇
  2013年   33篇
  2012年   29篇
  2011年   26篇
  2010年   45篇
  2009年   46篇
  2008年   30篇
  2007年   25篇
  2006年   17篇
  2005年   12篇
  2004年   11篇
  2003年   6篇
  2001年   9篇
  2000年   12篇
  1999年   11篇
  1998年   34篇
  1997年   33篇
  1996年   34篇
  1995年   37篇
  1994年   23篇
  1993年   20篇
  1992年   5篇
  1991年   6篇
  1990年   11篇
  1989年   15篇
  1988年   16篇
  1987年   15篇
  1986年   18篇
  1985年   10篇
  1984年   14篇
  1983年   18篇
  1982年   13篇
  1981年   15篇
  1980年   16篇
  1978年   9篇
  1977年   6篇
  1976年   8篇
  1975年   6篇
  1973年   5篇
  1970年   4篇
  1969年   5篇
  1968年   4篇
  1967年   7篇
排序方式: 共有838条查询结果,搜索用时 15 毫秒
91.
Light chain deposition disease (LCDD) results from a propensity of some human monoclonal L chains to form tissue deposits. We designed an experimental model for in vivo expression of human kappa L chain sequences in mice and compared a somatically mutated LCDD chain with a closely related control kappa chain, both encoded by the unique V kappa IV gene. Mice secreting the LCDD chain but not those producing the control chain showed deposits with a distribution similar to that observed in patients. These data show that discrete changes in V region sequences can play a major role in tissue deposition of human L chains.  相似文献   
92.
Ralph  QM; Brisco  MJ; Joshua  DE; Brown  R; Gibson  J; Morley  AA 《Blood》1993,82(1):202-206
The Ig heavy chain (IgH) gene was used as a marker to investigate clonal succession and the origin of the neoplastic cell in multiple myeloma. The polymerase chain reaction (PCR) was used to amplify a section of the rearranged IgH gene at diagnosis and at progression in 21 patients who had exhibited a plateau phase. A monoclonal PCR product was seen for 16 of the patients and the product present at progression was of the same molecular weight as that at diagnosis. This finding suggests that the IgH rearrangement present at diagnosis and progression was the same. This was confirmed by sequencing the IgH gene in 10 patients. The IgH genes were found to be hypermutated at diagnosis, but no further hypermutation occurred during the course of the disease. The results provide evidence that the neoplastic cell in myeloma may originate as a memory B cell, plasmablast, or plasma cell, and suggest that progression beyond the plateau phase is not caused by clonal succession.  相似文献   
93.
94.
Lipid peroxidation parameters malonic dialdehyde (MDA) and dienic conjugates (DC) and antioxidant defense (AOD) values superoxide dismutase (SOD), catalase, alpha-tocopherol were measured in the blood neutrophils and lacrimal fluid of 66 patients on days 1-2, 7-8, 14-15, and 21-22 after perforating wound of first, second, third, and fourth degree of severity according to P, 1. Lebekhov and in repeated injury, and the time course of these parameters during local treatment with therapeutic films with emoxipin and emoxipin + piridoxine was evaluated. A stable increase of MDA and DC levels in blood neutrophils, decrease of catalase, SOD, and alpha-tocopherol levels in blood neutrophils, and decrease of catalase enzymes and SOD activities in the lacrimal fluid of injured eye starting from days 7-8 are prognostically unfavorable signs. These data prompt the use of local and systemic treatment with antioxidants (emoxipin, tocopherol, etc.) in perforating wounds starting from the first days after the injury. Good clinical and antioxidant effect was observed after treatment with ocular therapeutic films with emoxipin and piridoxine.  相似文献   
95.
Clinical and immunological studies in 170 patients with senile cataracts carried out before and during the first 7 days after cataract extraction with implantation of intraocular lenses helped define the risk factors for development of an early exudative reaction: patients' age under 60 years, clinical signs of secondary immune deficiency presenting as infection syndrome, increased levels of nonspecific immunity factors with deterioration of the phagocytic component, T-lymphopenia, CD4/CD8 imbalance, and increased levels of interleukin-1 beta and tumor necrosis factor in the serum and lacrimal fluid.  相似文献   
96.
The Film Digital Radiography System (FilmDRS) is a device with a laser optical film digitizer, 2,000 X 2,000 X 12-bit memory, and a 1,000-line video display. To evaluate the adequacy of this device for general radiography of the chest, four readers independently analyzed both radiographs and the corresponding video display of the digitized chest images of 150 patients, consisting of 100 images of abnormalities and 50 normal images. The overall results indicate equal sensitivity for the two systems. The FilmDRS, with interactive windowing, proved superior in the detection of hilar and mediastinal disease. X-ray film was superior in allowing detection of hyperlucent states. There was equivalent sensitivity for other disease categories. Superior specificity was achieved with conventional radiographs.  相似文献   
97.
98.
99.
The systemic administration of IFN-alpha/beta was previously found to suppress inflammation in rats with experimental autoimmune uveoretinitis (EAU); however, an effect on the systemic immune response was not identified. In order to investigate an immunological basis for suppression at the intraocular level, rats immunized with interphotoreceptor retinoid-binding protein (IRBP) were administered daily intramuscular injections of 10(5) IU IFN-alpha/beta and cytokines were measured by ELISA in intraocular extracts prepared by ultrasonification at various timepoints throughout the course of EAU. In control EAU, intraocular concentrations of IFN-gamma were found to be non-detectable on day 8 before the onset of inflammation, significantly elevated on day 12 at peak inflammation (182+/-106 pg/ml), then non-detectable again on day 16 after inflammation had begun to subside. In contrast, intraocular IFN-gamma in IFN-alpha/beta- treated rats remained non-detectable or low at all timepoints. Measurement of intraocular IL-2 revealed no difference between the two groups of rats. Intraocular IL-4 concentrations were elevated in rats treated with IFN-alpha/beta, although this cytokine was also detected in the same range in controls as well as normal rats. Finally, intraocular IL-10 was non-detectable on day 8, significantly elevated at peak inflammation on day 12 (588+/-139 pg/ml), then decreased to low levels on day 16 in control EAU rats, while remaining non-detectable or low in IFN-alpha/beta-treated rats. These results suggest that acute inflammation in IRBP-induced EAU in rats involves both IFN-gamma and IL- 10 at the local intraocular level, and that systemic administration of IFN-alpha/beta inhibits EAU via a mechanism that involves suppression of both cytokines.   相似文献   
100.
Summary— In order to test whether the β-adrenoceptor activity in rheumatic heart valvular disease depends on the ventricular load conditions, we determined their density and binding affinity to [125I]-iodocyanopindolol in lymphocytes, as well as plasma catecholamine and cAMP levels in 69 patients with regurgitant and stenotic lesions of the aortic and mitral valves. The patients were classified as having left ventricular pressure overload (LVP), left ventricular volume overload (LVV), mixed lesions (MOL) or right ventricular pressure overload (RVP). The β-adrenoceptor activity was determined by radioligand binding methods, catecholamines by high performance liquid chromatography using an electrochemical detector and cAMP by radioimmunoassay. The mean β-adrenoceptor density (Bmax) of the control group was 60.1 ± 9.5 /mol ( n = 29) per 106 lymphocytes. In the study population, the density was decreased by 83% in LVP, 78% in LVV, 87% in MOL and 86% in RVP. Plasma norepinephrine was elevated by 89% in LVP and 60% in MOL, epinephrine by 43% in LVP, 50% in VOL, 115% in MOL and 20% in RVP, while dopamine was not significantly changed, and cAMP was slightly elevated in all four groups. Screening for activating mutational changes in the G-protein gave negative results, possibly dissociating the elevation in plasma cAMP from stimulatory effects of such abnormalities in the Gs-protein signaling. These results show a significant attenuation in lymphocyte β-adrenoceptor density of patients with rheumatic heart valvular disease, irrespective of the type of the prevailing ventricular load conditions. The reduction in receptor density is accompanied by a significant increase in plasma norepinephrine levels in patients with a left ventricular pressure overload and epinephrine in those with volume overload.  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