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   1496篇
  免费   115篇
  国内免费   4篇
耳鼻咽喉   23篇
儿科学   78篇
妇产科学   8篇
基础医学   273篇
口腔科学   23篇
临床医学   165篇
内科学   405篇
皮肤病学   33篇
神经病学   145篇
特种医学   156篇
外科学   117篇
综合类   11篇
预防医学   90篇
眼科学   5篇
药学   44篇
肿瘤学   39篇
  2023年   6篇
  2022年   17篇
  2021年   24篇
  2020年   19篇
  2019年   14篇
  2018年   32篇
  2017年   23篇
  2016年   19篇
  2015年   39篇
  2014年   40篇
  2013年   43篇
  2012年   63篇
  2011年   80篇
  2010年   56篇
  2009年   52篇
  2008年   56篇
  2007年   54篇
  2006年   51篇
  2005年   51篇
  2004年   44篇
  2003年   45篇
  2002年   37篇
  2001年   31篇
  2000年   39篇
  1999年   36篇
  1998年   48篇
  1997年   56篇
  1996年   53篇
  1995年   44篇
  1994年   34篇
  1993年   30篇
  1992年   24篇
  1991年   31篇
  1990年   23篇
  1989年   40篇
  1988年   43篇
  1987年   33篇
  1986年   39篇
  1985年   22篇
  1984年   12篇
  1983年   10篇
  1982年   9篇
  1981年   19篇
  1980年   9篇
  1979年   10篇
  1978年   13篇
  1977年   11篇
  1976年   5篇
  1975年   14篇
  1974年   10篇
排序方式: 共有1615条查询结果,搜索用时 0 毫秒
91.
Ring chromosome 20 epilepsy syndrome in children: electroclinical features   总被引:1,自引:0,他引:1  
Ring chromosome 20 mosaicism is associated with dysmorphic features, mental retardation, and intractable seizures, including recurrent episodes of nonconvulsive status epilepticus. The authors' findings in four children, all without dysmorphic features, indicate that mental deterioration and frequent subtle nocturnal frontal lobe seizures, associated with a characteristic EEG pattern, represent prominent additional clinical features not previously described in this syndrome. This emphasizes the importance of full-night video-EEG in children with frontal lobe seizures and cognitive deterioration.  相似文献   
92.
In order to test the hypothesis that integrin and uteroglobin (UG) expression in cultured endometrial cells are affected by hormone treatment, Ishikawa-CH endometrial cancer cells were cultured and exposed to oestradiol or oestradiol and progesterone regimens and assayed using immunohistochemistry. We evaluated the intensity of immunohistochemical staining for the integrin monomers alpha(v) and beta1, the dimers alpha(v)beta3 and alpha(v)beta6, and for the secretory protein uteroglobin under various experimental conditions. Cells grown in control media stained positively for the integrin monomers alpha(v) and beta1, the dimer alpha(v)beta3, and for UG. Oestradiol and sequential oestradiol/progesterone reversibly suppressed staining for the dimer alpha(v)beta3. Hormone treatment had no effect on the staining of the beta1 and alpha(v) monomers or UG. The alpha(v)beta6 dimer antibody did not stain under any experimental treatment conditions. These data indicate that expression of the integrin complex alpha(v)beta3 is reversibly suppressed by oestradiol in Ishikawa cells and that these cells may be a good model for studying hormone-driven molecular changes in endometrium.   相似文献   
93.
94.
A simple test to predict the outcome of intracavernous papaverine treatment would be helpful in the management of erectile dysfunction. Doppler studies of the flaccid penis were compared with the results of intracavernous injection of papaverine. There was no correlation between these two. Therefore Doppler studies of the flaccid penis are not appropriate to predict the effect of intracavernous injection.  相似文献   
95.
Background and objective: Patients with OSA manifest different patterns of disease. However, this heterogeneity is more evident in patients with mild‐moderate OSA than in those with severe disease and a high total AHI. We hypothesized that mild‐moderate OSA can be categorized into discreet disease phenotypes, and the aim of this study was to comprehensively describe the pattern of OSA phenotypes through the use of cluster analysis techniques. Methods: The data for 1184 consecutive patients, collected over 24 months, was analysed. Patients with a total AHI of 5–30/h were categorized according to the sleep stage and position in which they were predominantly affected. This categorization was compared with one in which patients were grouped using a K‐means clustering technique with log linear modelling and cross‐tabulation. Results: Patients with mild‐moderate OSA can be categorized according to polysomnographic parameters. This clinical categorization was validated by comparison with a categorization in which patients were grouped by unsupervised K‐means cluster analysis. The clinical groups identified were: (i) rapid eye movement (REM) predominant OSA, 44.6%; (ii) non‐REM predominant OSA, 18.9%; (iii) supine predominant OSA, 61.9%; and (iv) intermittent OSA, 12.4%. Patients categorized as having both REM and supine predominant OSA showed characteristics of both the REM predominant and supine predominant OSA groups. Conclusions: Patients with mild‐moderate OSA show different polysomnographic phenotypes. This approach to categorization more appropriately reflects disease heterogeneity and the likely multiple pathophysiological processes involved in OSA.  相似文献   
96.
To understand better the relationships between blood-group antigens and bacterial constituents, examples of 23 gram-negative bacteria (representing the 10 genera Citrobacter, Edwardsiella, Enterobacter, Escherichia, Klebsiella, Proteus, Pseudomonas, Salmonella, Serratia, and Shigella) were tested for the presence of Kl-like antigens by hemagglutination-inhibition (HAI) assays against both IgG and IgM anti-Kl. Saline-suspended whole organisms, cell-free culture media, and disrupted organisms were used to test for such antigens in, on, and secreted by the microorganisms examined. Disrupted organisms of an isolate of Shigella sonnei nonspecifically inhibited IgG anti-Kl as well as IgG antibodies of the specificities Kpb, Fya, S, and c. However, only Escherichia coli 0125:B15, subtype 12808, had specific K1-like activity (no activity with other IgG [(k, Kpb, Jka, Fya, S, c] and IgM [A, B, M, P1] antibodies). Disrupted organisms inhibited IgM but not IgG anti-K1 in the HAI assay. A second subtype, E. coli 0125:B15, subtype 12809, exhibited no K1-like activity. These findings support the report of K1 activity in cell-free broth cultures of E. coli 0125:B15 (subtype unspecified). Thus, although not all E. coli 0125:B15 possesses K1-like activity, the finding of such activity in at least one E. coli subtype confirms the idea that bacterial components may play a role in the production of naturally occurring antibodies directed against non-ABO red cell antigens.  相似文献   
97.
Daclizumab, a humanized antibody directed against the alpha-chain of the interleukin-2 receptor (CD25), has shown efficacy in the prevention of acute rejection following organ transplantation. However, anti-CD25 therapy can be expected to affect not only alloreactive effector T cells, but also CD4(+)CD25(+) regulatory T (Treg) cells that are shown to play an important role in the induction of transplantation tolerance. Therefore, the size and function of the Treg pool in human renal allograft recipients after single-dose daclizumab administration was investigated in this study. Approximately 8 weeks after administration, daclizumab was cleared from the circulation and the Treg population then present appeared not different from that observed before transplantation. Functional analysis revealed that the Treg possessed a normal capacity to suppress mixed lymphocyte reactions in vitro. These data indicate that after daclizumab therapy a Treg population, normal in number and function, is present in the peripheral blood of renal transplant recipients.  相似文献   
98.
T-cell hybridomas are highly metastatic, and their in vitro invasiveness correlates with metastatic capacity. Invasion is blocked by pertussis toxin (PT), which adenosine diphosphate (ADP)-ribosylates G1-proteins, and we have provided evidence that the PT-sensitive signal stimulates leukocyte function-associated antigen-1 (LFA-1)-mediated adhesion required for invasion. PT pretreatment of TAM2D2 T-cell hybridoma cells reduced metastasis, but only to a limited extent. In the present study, we have transfected the cDNA of the PT ADP- ribosyltransferase S1 subunit into TAM2D2 cells to abrogate G1-protein function permanently. We report here a substantial reduction in the metastatic capacity of two transfectants, S05 and S09, in which 88% and 95% of the G1-proteins was ADP-ribosylated. Two-thirds of the mice injected with S09 cells were tumor-free. Metastasis to the liver was almost completely prevented and less metastases were formed in the spleen and kidneys. Metastasis formation by S05 cells in liver and spleen was much reduced, but in lymph nodes and peritoneal tissues, metastases occurred with a frequency similar to that of controls. We conclude that G1-proteins play an important role in T-cell hybridoma metastasis. We propose that the reduction in metastasis is due to diminished entry of tumor cells from the blood into tissues.  相似文献   
99.
A multicenter clinical study was conducted using iohexol, a second-generation nonionic contrast medium, for excretory urography performed in 130 children. Doses of iohexol (300 mg iodine/ml) ranged between 150 and 660 mgI/kg (0.5 and 2.2 ml/kg). Iohexol was tolerated well, and no significant adverse reactions occurred. Sixty-five iohexol urograms were evaluated to determine the minimum dose for adequate visualization of the kidneys and collecting systems. A dose greater than 300 mgI/kg (1.0 ml/kg) always resulted in a urogram of diagnostic quality, while visualization was insufficient for diagnosis in 10% of studies done with doses of 150-300 mgI/kg (0.5-1.0 ml/kg). Another 65 iohexol urograms were compared in a blinded manner with a similar number of studies performed using iothalamate meglumine at comparable iodine concentration and dose. Visualization of calyces and pelvoinfundibular structures achieved with iohexol was rated better with statistical significance, but there was no difference in visualization of the renal parenchyma or ureters. Use of iohexol in excretory urography may be advantageous in children who are at greatest risk for an adverse reaction to contrast media or in those most likely to benefit from use of a low osmolality contrast agent.  相似文献   
100.
Volumetric rendering is a new approach to three-dimensional (3D) imaging that overcomes many of the drawbacks of currently available surface-rendering systems. Its application on the Pixar Imaging System in two cases of acetabular fracture was assessed to illustrate the features of the technique. The fast-computing architecture and large memory of this system allow rapid generation of a series of high-quality 3D images in each plane of rotation (x or spinal axis, z or somersaulting axis) that can be viewed as independent static images or as an animated real-time video loop. Editing to remove the normal contralateral hemipelvis enhances appreciation of acetabular abnormalities. Every pixel of computed tomographic data is preserved, allowing representation of both soft tissue and bone as translucent overlap. The presentation of data also allows detection of subtle abnormalities and features and minimizes the artifact generation common in surface-rendered images.  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