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   32923篇
  免费   2436篇
  国内免费   1020篇
耳鼻咽喉   360篇
儿科学   423篇
妇产科学   372篇
基础医学   5090篇
口腔科学   516篇
临床医学   3398篇
内科学   5215篇
皮肤病学   803篇
神经病学   2366篇
特种医学   1606篇
外国民族医学   5篇
外科学   3791篇
综合类   2527篇
现状与发展   7篇
一般理论   9篇
预防医学   1800篇
眼科学   838篇
药学   3477篇
  15篇
中国医学   1086篇
肿瘤学   2675篇
  2024年   38篇
  2023年   346篇
  2022年   472篇
  2021年   1500篇
  2020年   866篇
  2019年   947篇
  2018年   1085篇
  2017年   863篇
  2016年   1095篇
  2015年   1534篇
  2014年   1859篇
  2013年   2024篇
  2012年   2859篇
  2011年   2963篇
  2010年   1741篇
  2009年   1441篇
  2008年   2015篇
  2007年   1899篇
  2006年   1702篇
  2005年   1597篇
  2004年   1254篇
  2003年   1071篇
  2002年   887篇
  2001年   709篇
  2000年   736篇
  1999年   584篇
  1998年   276篇
  1997年   226篇
  1996年   176篇
  1995年   171篇
  1994年   142篇
  1993年   104篇
  1992年   161篇
  1991年   173篇
  1990年   141篇
  1989年   107篇
  1988年   90篇
  1987年   82篇
  1986年   72篇
  1985年   53篇
  1984年   35篇
  1983年   34篇
  1982年   30篇
  1981年   22篇
  1980年   21篇
  1979年   30篇
  1978年   21篇
  1977年   17篇
  1976年   14篇
  1974年   17篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
13例肝结核临床分析   总被引:3,自引:0,他引:3  
我院于1998年1月-2005年5月共收治13例肝结核病患者,现分析如下。  相似文献   
73.
烧伤后早期应用中/长链甘油三酯对患者免疫功能的影响   总被引:5,自引:1,他引:4  
目的 探讨烧伤后早期肠内喂养中链甘油三酯 (MCT) /长链甘油三酯 (LCT)对机体免疫功能的影响及其可能机制。 方法 选取 30例烧伤面积 >30 %TBSA的患者 ,随机分为两组 (每组 15例 )。F组 ,饲以含MCT/LCT的肠内营养制剂Fresubin 75 0MCT ;N组 ,饲以只含LCT的肠内营养制剂Nutrison。于伤后 2 4h内进行完全肠内营养支持 ,共持续 10d。于伤后 1、4、7、10d检测两组患者血浆白细胞介素 (IL) 2、IL 4、前列腺素 (PG)E2 及外周血T淋巴细胞转化率的改变。 结果 伤后各时相点F组患者血浆IL 2水平与N组相比 ,无明显差异 (P >0 .0 5 ) ;伤后 4dF组PGE2 水平较N组明显降低 (P <0 .0 1) ;伤后 4、7、10dF组IL 4水平及外周血T淋巴细胞转化率均明显高于N组 (P <0 .0 5~ 0 .0 1)。 结论 在改善烧伤后机体的免疫功能方面 ,含MCT/LCT的肠内营养制剂较单纯LCT制剂更具优势。  相似文献   
74.
喉癌染色体6q25区域的杂合性丢失和微卫星不稳定性分析   总被引:1,自引:0,他引:1  
目的:在6q25区域内筛查喉癌相关的基因,探计胰岛素样生长因子受体Ⅱ(IGF2R)基因及脆性住点FRA6E在喉癌发生中的作用。方法:在6q25区域选择3个微卫星多态标记,其中D6S980位于IGF2R的5′端且与FRA6E紧密连锁。应用聚合酶链式反应-聚丙烯酰胺尿素凝胶电泳-DNA银染方法对70例喉癌进行杂合性丢失(LOH)和微卫星不稳定性(MI)分析。结果:在这3个座位上,喉癌LOH频率以D6s980处最高,达41.4%,MI频率为26.8%。总的异常频率为68.2%。LOH和MI与喉癌临床分期无关。结论:提示IGF2R可能是喉癌相关的抑癌基因。脆性位点FRA6E所在的染色体区段可能存在与喉癌相关的肿瘤抑制基因。  相似文献   
75.
复方胰岛素凝胶剂促进大鼠皮肤溃疡愈合的初步研究   总被引:2,自引:0,他引:2  
周冼苡  周雪雪  曾抗 《中国美容医学》2006,15(2):124-126,i0001
目的:研究复方胰岛素凝胶剂对大鼠皮肤溃疡的促愈合作用,并探讨其可能的作用机制。方法:18只Wistar大鼠背部各制备4个皮肤溃疡模型,共复制溃疡72个,随机将溃疡分为复方胰岛素凝胶治疗组(A组)、凝胶基质对照组(B组)、空白对照组(C组)。以治疗后不同时间点各组溃疡面积、溃疡愈合速度及组织病理学检查评价修复效果。结果:在伤后头10天内,A组溃疡缩小最明显,愈合速度明显快于B组、C组。伤后14天,A组溃疡基本愈合,皮肤结构完整、上皮化较厚;而B、C组溃疡仍未完全愈合,皮肤结构不完整、上皮化较薄。结论:局部应用复方胰岛素凝胶剂对大鼠皮肤溃疡有促愈合作用。  相似文献   
76.
用多粘菌素B琼脂糖亲和层析法清除内毒素,结果表明:5ml多粘菌素B层析柱的总吸附内毒素能力为450 μg,用此法可完全清除体液或各种液体中的内毒素,对血清及腹水中的内毒素也有明显的吸附作用,而其他各种主要成分(除内毒素外)经过处理后无明显改变。去氧胆酸是一种强有力的去污剂,可使已饱和的柱子复活,复活率达85%左右。该方法有简便,可靠,吸附能力大,柱子的复活率高等优点。本方法的建立为内毒素血症的治疗展示了新的前景。  相似文献   
77.
1. The in vivo whole bladder preparation was used to correlate bladder volume with the ability of urinary bladders from control, sucrose-drinking, and diabetic rats to develop pressure in response to bethanechol or nerve stimulation. 2. Both streptozotocin-induced diabetes mellitus and sucrose-diuresis caused an increase in rat urinary bladder capacity and mass. 3. There were significant decreases in the ability of bladders from control rats to develop pressure in response to bethanechol at 1.0 ml intravesical volume, but no change in responsiveness of bladders from sucrose-drinking or diabetic rats at different intravesical volumes. Bladders from sucrose-drinking and diabetic rats developed significantly less pressure in response to bethanechol stimulation at low intravesical volumes than did bladders from control rats. 4. Bladders from diabetic rats developed significantly less pressure in response to 32 Hz stimulation at 0.2 ml intravesical volume compared to larger volumes, however, there were no differences in the responses of bladders from sucrose-drinking or control rats at any intravesical volume. 5. Bladders from control and sucrose-drinking rats had a reduced ability to empty in response to bethanechol and field stimulation at large intravesical volumes. 6. Bladders from 8-week streptozotocin-diabetic rats are able to contract and empty efficiently in response to nerve stimulation and bethanechol over a wide range of intravesical volumes.  相似文献   
78.
5-(2-Acylethynyl)-2,4-dimethoxypyrimidines (3-6) were synthesized in excellent yields from 2,4-dimethoxy-5-[2-(trimethylsilyl)ethynyl]pyrimidine (2) by treatment with acid chlorides in the presence of anhydrous aluminum chloride. Compounds 3-6 were deblocked with chlorotrimethylsilane and sodium iodide in acetonitrile to the corresponding 5-[(2-acyl-1-iodo)vinyl]uracils (7-10), which on treatment with potassium hydroxide in dioxane yielded the corresponding 5-(2-acylethynyl)uracils (11-14). The 5-(2-acylethynyl)uracils were found to be active against Ehrlich ascites carcinoma (EAC) cells in vivo, the most active compounds being 5-(2-benzoylethynyl)uracil (11) and 5-(2-p-toluoylethynyl)uracil (12). The T/C values of 281 and 300 were obtained for compounds 11 and 12, respectively, in the case of mice bearing EAC cells. The 5-(2-acylethynyl)uracils have also shown in vitro activity against CCRF-CEM and L1210/0 tumor cell lines. The lead compound 5-(2-p-toluoylethynyl)uracil effectively inhibited thymidylate synthetase.  相似文献   
79.
Ten (E)-and (Z)-isomers of 2-phenylcyclopropylamine (PCA), 1-Me-PCA, 2-Me-PCA, N-Me-PCA, and N, N-diMe-PCA and fifteeno , m, p isomers of (E)-PCA with substituents of Me, Cl, F, OMe, OH were synthesized in this laboratory and tested for the inhibition of rat brain mitochondrial MAO-A and MAO-B. The effects of substituents, their positions, and stereochemistry on the inhibition were assessed for the compounds with substituents at cyclopropyl and amino groups and QSAR analyses were performed using the potency data of ring-substituted compounds. The best correlated QSAR equations are as follows: pI50=0.804 Π2 Blo−1.069 Blm+0.334 Lp−1.709 HDp+7.897 (r=0.945, s=0.211, F=16.691, p=0.000) for the inhibition of MAO-A; pI50=1.815 π-0.825 Π2 R+0.900 Es2+0.869 Es3+0.796 Es4−0.992 HDp+0.562 HAo+3.893 (r=0.982, s=0.178, F=23.351, p=0.000) for the inhibition of MAO-B. Based on the potency difference between stereoisomers of cyclopropylamine-modified compounds and on QSAR results, it is proposed that the active sites of MAO-A are composed of one deep hydrophobic cavity near para position, two hydrophobic cavities interacting with Me group, a hydrophobic area accomodating phenyl and cyclopropyl backbone, steric boundaries, a hydrogen-acceptor site near para position, and an amino group binding site and that in addition to the same two hydrophobic cavities, hydrophobic area, steric boundaries, hydrogen-acceptor site, and amino group binding site, another steric boundary near para position and a hydrogen donating site near ortho position constitute active sites of MAO-B.  相似文献   
80.
M He  A S Kang  M Hamon  A S Humphreys  M Gani    M J Taussig 《Immunology》1995,84(4):662-668
The heavy chain variable region (VH) and the kappa light chain of the anti-progesterone monoclonal antibody (mAb) DB3, have been expressed as a single-chain three-domain polypeptide, designated VH/K, and secreted into the periplasmic space of Escherichia coli (E. coli). The linker sequence was derived from the VH-CH1 elbow region. The C kappa domain provides a sensitive detection tail for Western blotting and enzyme-linked immunosorbent assay (ELISA). Periplasmic extracts of transformed E. coli contained material that bound progesterone and related steroids with similar specificity and affinity to DB3, and displayed the DB3 idiotype and kappa chain epitopes. Reference to the crystal structure of DB3 suggests that all the characteristics of the combining site interaction with steroids are retained in the bacterially expressed material. Western blotting demonstrated material with a molecular weight equivalent to three domains after reduction, but six domains in the unreduced state, suggesting that the VH/K polypeptide is assembled in the periplasm as a disulphide-bridged dimer. The VH/K construct provides a novel route to expression of antibody combining sites in E. coli for antibody engineering.  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