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   1322篇
  免费   139篇
  国内免费   17篇
耳鼻咽喉   7篇
儿科学   12篇
妇产科学   40篇
基础医学   108篇
口腔科学   700篇
临床医学   103篇
内科学   102篇
皮肤病学   7篇
神经病学   35篇
特种医学   6篇
外科学   58篇
综合类   59篇
预防医学   38篇
眼科学   3篇
药学   80篇
中国医学   44篇
肿瘤学   76篇
  2024年   1篇
  2023年   34篇
  2022年   58篇
  2021年   87篇
  2020年   76篇
  2019年   131篇
  2018年   91篇
  2017年   57篇
  2016年   63篇
  2015年   48篇
  2014年   111篇
  2013年   92篇
  2012年   67篇
  2011年   75篇
  2010年   59篇
  2009年   61篇
  2008年   63篇
  2007年   59篇
  2006年   55篇
  2005年   48篇
  2004年   40篇
  2003年   25篇
  2002年   17篇
  2001年   11篇
  2000年   9篇
  1999年   2篇
  1998年   5篇
  1997年   8篇
  1996年   4篇
  1995年   2篇
  1994年   3篇
  1993年   3篇
  1991年   2篇
  1989年   2篇
  1988年   1篇
  1986年   1篇
  1985年   3篇
  1984年   1篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
排序方式: 共有1478条查询结果,搜索用时 46 毫秒
1.
2.
In an outpatient rehabilitation setting, both patients’ use and therapists’ knowledge of complementary and alternative medicine (CAM) varies widely. Based on this observation and a recognition of CAM as an emerging practice area for rehabilitation professionals, it was felt that a thorough and consistent approach to the education and orientation of physical therapists to the world of CAM and integrative care was needed. This special interest paper will describe one center’s approach, development, and use of a unique and comprehensive training manual designed to provide both a structured and standardized approach for educating physical therapists about CAM and related therapeutic modalities. This innovative teaching tool allows for multiple methods of content delivery within a multidisciplinary format and can be used for those who practice currently or desire to practice in an integrative care environment.  相似文献   
3.
CAM 4515 and CAM 4750 are new nonpeptide tachykinin NK1 receptor antagonists with different lipophilicities. Two separate, simple, and sensitive HPLC methods for the quantitation of these two compounds in plasma and the evaluation of their oral bioavailability in rats were developed and validated. Extraction of CAM 4515 from plasma involved protein precipitation with acetonitrile, while that for CAM 4750 involved a one-step liquid-liquid extraction with methylene chloride. The analytes in extracts were chromatographed on a C18 column using two different separation buffers, 47% 0.02 M sodium citrate (pH 3.5)-53% acetonitrile for CAM 4515 and 59% 0.02 M potassium phosphate dibasic (pH 7.0)-41% acetonitrile for CAM 4750, and both compounds were detected by fluorescence (excitation 278 nm; emission 342 nm). Stability profiles of both drugs at −20°C or room temperature in plasma and in reconstituted buffers were good. The limit of quantitation for both drugs was 5 ng ml−1 with good linearity from 5 to 1000 ng ml−1 using 100–200 μl of plasma. Excellent precision (relative standard deviation < 8.3%) and accuracy (relative error ± 9.2%) were observed for both CAM 4515 and CAM 4750. Oral bioavailability studies were conducted for each compound in rats receiving a p.o. dose of 20 mg kg−1 and an i.v. dose of 5 mg kg−1. The absolute oral bioavailability of CAM 4750 (80%) was estimated to be 40-fold greater than that of CAM 4515 (2%). The experimental results suggest that incorporation of a pyridine group into the structural backbone may greatly improve bioavailability.  相似文献   
4.
KL-6, a circulating mucin-like glycoprotein, is a pulmonary adenocarcinoma-associated antigen and is also regarded as an indicator of disease activity of interstitial pneumonitis. KL-6 has extensive heterogeneous antigenic determinants and consists of multiple heterogeneous antigen molecules. We have searched for circulating KL-6-associated glycoproteins with superior diagnostic value to KL-6 as a tumor marker for pulmonary adenocarcinoma. A new murine monoclonal antibody EH-123 reacting with an asialosugar chain on KL-6 was established. A new KL-6-associated molecule detected by a bimonoclonal bideterminant sandwich assay using the EH-123 antibody as a catcher and horseradish peroxidase-labeled KL-6 as a tracer was designated as CAM 123-6. In 59% (22 of 37) of patients with pulmonary adenocarcinoma, serum levels of CAM 123-6 were abnormally elevated and the positive rate increased with the progression of clinical stage. Elevated levels were not detected in normal individuals or in patients with benign lung diseases, other histologic types of lung cancer, gastric cancer, colon cancer or breast cancer. CAM 123-6 was more specific to pulmonary adenocarcinoma than carcinoembryonic antigen (CEA), but the sensitivity of CAM 123-6 for pulmonary adenocarcinoma was similar to that of CEA. CAM 123-6 is a promising candidate as a serum tumor marker for pulmonary adenocarcinoma.  相似文献   
5.
Congenital hydrocephalus associated with aqueductal stenosis and/or agenesis of the corpus callosum has been described in newborn males with mutations in L1CAM, a gene that encodes a neural cell adhesion molecule. These males usually have severe mental retardation and may have spastic paraplegia and adducted thumbs. In contrast, Hirschsprung disease, or absence of ganglion cells in the distal gut, has rarely been described in such individuals. We report a male infant who had severe hydrocephalus identified in the prenatal period with evidence of aqueductal stenosis and adducted thumbs at birth. He developed chronic constipation, and rectal biopsy confirmed the diagnosis of Hirschsprung disease. Molecular testing of the L1CAM gene revealed a G2254A mutation, resulting in a V752M amino acid substitution. A common polymorphism in RET, but no mutation, was identified. Our patient represents the third example of coincident hydrocephalus and Hirschsprung disease in an individual with an identified L1CAM mutation. We hypothesize that L1CAM‐mediated cell adhesion may be important for the ability of ganglion cell precursors to populate the gut, and that L1CAM may modify the effects of a Hirschsprung disease–associated gene to cause intestinal aganglionosis. © 2002 Wiley‐Liss, Inc.  相似文献   
6.
The MASA syndrome is an X-linked disorder with mental retardation, spastic paraparesis, and adducted thumbs as the most characteristic features. We performed linkage analysis, using Xq28 markers, on a large MASA syndrome family. The maximum lodscore was 6.37 at 0 recombination for DXS52 and 5.99 at 0 recombination for DXS305. Crossovers were demonstrated between the disorder and DXS455. Clinical and linkage data from this family further support the hypothesis that the MASA syndrome and X-linked hydrocephalus are allelic disorders.  相似文献   
7.
Summary The application of Thermanox tissue culture coverslips to the day 9 CAM of the chick causes constant effects beneath the carrier after 3 days, and these are associated with a change in the blood vessel pattern. Histological sections show enormous thickening of the CAM in the reactive areas. The stroma of the CAM shows fibrocyte proliferation, leucocyte infiltration, and clusters of dispersed ectodermal epithelial cells exhibiting signs of necrosis. The latter obviously cause a strong vascular response. The same effects are seen when the Thermanox discs are applied at day 11. Following application on day 12 a positive or negative response to the carrier is observed, whereas on day 13 no such carrier effects are seen. The only remaining effect is compression of the intra-ectodermal capillary plexus of the CAM. This can macroscopically be seen after peroxidase staining of the blood vessels. The effect of 5 l PBS dried on the Thermanox disc and applied to the day 13 CAM is to cause, after 3 days, hyperosmotic damage to the ectodermal epithelium, which becomes overgrown by fibrocytes. We found dose-dependent effects of salt-free human bFGF applied to the day 13 CAM. The first and main effect is fibrocyte proliferation (0.5 g). New capillaries appear with higher doses, but are not as frequent as would be expected for an angiogenic substance (1.25–2.5 g). Also with higher doses additional hyperplasia of the endodermal (3.75 g) and ectodermal (5 g) epithelium can be seen. The latter might be a non-specific hyperosmotic effect. Leucocytes are regularly present within the reactive areas. When salt-free angiogenin is applied to the day 13 CAM, some effects appear with doses of 4.6 g and more. The ectodermal epithelium of the reactive areas is discontinuous, exhibiting signs of necrosis. It is overgrown by parallel fibrocytes. Whether this is a non-specific hyperosmotic effect, or indicates enhancement of invasive growth, calls for further investigation.  相似文献   
8.
Interleukin-2 (IL-2), an immunoregulatory cytokine possessing antitumour activity, is an inducer of nitric oxide (NO) synthesis in mice and man. In this study, the possibility that IL-2 possesses antiangiogenic properties that account for its antitumour effects in vivo was examined. IL-2 caused a dose-dependent inhibition of angiogenesis in the chick embryo chorioallantoic membrane (CAM). This inhibition was completely reversed by the NO synthase inhibitor NG-nitro-L-arginine methylester (L-NAME). Furthermore, IL-2 was capable of stimulating NO synthase activity in the CAM in vitro and this effect was suppressed by L-NAME. Addition of IL-2 to human umbilical vein endothelial cells (HUVECs) in culture, had no effect on their growth characteristics. These results suggest that IL-2 may be an important antiangiogenic molecule causing its effect via nitric oxide synthesis. The antiangiogenic activity of IL-2 may be, at least in part, responsible for its antitumour properties.  相似文献   
9.
 目的 探讨血清可溶性细胞间粘着分子 1(sICAM 1)在上皮性卵巢癌中的临床意义。方法 利用ELISA法检测血清sICAM 1浓度。结果 卵巢上皮癌患者血清sICAM 1平均浓度和阳性率与良性卵巢瘤组和正常对照组相比有显著性差异 (P <0 .0 0 1) ;II~Ⅳ期显著高于临床Ⅰ期的患者 ;淋巴结转移阳性显著高于淋巴结转移阴性的患者 ;组织分化程度Ⅲ级者高于Ⅰ、Ⅱ级 (P <0 .0 1)。结论 血清sICAM 1检测可能有助于监测上皮性卵巢癌患者的病情和判断预后  相似文献   
10.
槲皮素抑制血管生成作用的实验研究   总被引:21,自引:1,他引:21  
目的 研究槲皮素 (Quercetin)对血管生成和培养的人脐静脉内皮细胞 (HUVEC)的影响。方法 采用生长因子 (血管内皮细胞生长因子VEGF、碱性成纤维细胞生长因子bFGF)诱导的鸡胚绒毛尿囊膜 (CAM)血管增生模型观察槲皮素对血管生成的影响 ;利用培养的HUVEC ,用MTT法观察槲皮素抑制内皮细胞增殖的作用 ;流式细胞仪观察槲皮素对HUVEC细胞周期的影响。结果 槲皮素 (0 1、0 0 5和 0 0 2 5mmol·L-1)能明显抑制VEGF诱导的CAM小血管生成 ;槲皮素 (0 1和 0 0 5mmol·L-1)能明显抑制bFGF诱导的CAM小血管生成 ;槲皮素 (2 4 0、12 0 μmol·L-1和 6 0 μmol·L-1)对内皮细胞增殖有抑制作用 ,抑制率分别为 6 7 0 %、5 8 1%和39 7% ;槲皮素 (2 4 0、12 0 μmol·L-1)能显著导致HUVEC的S、G2 期阻滞。结论 槲皮素能抑制VEGF和bFGF诱导的血管生成 ,且对内皮细胞增殖具有抑制作用。  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