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   10537篇
  免费   1007篇
  国内免费   423篇
耳鼻咽喉   117篇
儿科学   212篇
妇产科学   183篇
基础医学   1482篇
口腔科学   135篇
临床医学   1295篇
内科学   1617篇
皮肤病学   443篇
神经病学   565篇
特种医学   490篇
外国民族医学   7篇
外科学   925篇
综合类   905篇
现状与发展   2篇
一般理论   4篇
预防医学   627篇
眼科学   309篇
药学   1384篇
  5篇
中国医学   489篇
肿瘤学   771篇
  2024年   14篇
  2023年   121篇
  2022年   249篇
  2021年   474篇
  2020年   324篇
  2019年   378篇
  2018年   395篇
  2017年   343篇
  2016年   439篇
  2015年   598篇
  2014年   718篇
  2013年   676篇
  2012年   1052篇
  2011年   997篇
  2010年   563篇
  2009年   491篇
  2008年   629篇
  2007年   574篇
  2006年   457篇
  2005年   466篇
  2004年   337篇
  2003年   312篇
  2002年   258篇
  2001年   132篇
  2000年   139篇
  1999年   148篇
  1998年   91篇
  1997年   89篇
  1996年   59篇
  1995年   65篇
  1994年   41篇
  1993年   33篇
  1992年   53篇
  1991年   36篇
  1990年   31篇
  1989年   26篇
  1988年   22篇
  1987年   25篇
  1986年   11篇
  1985年   16篇
  1984年   6篇
  1983年   10篇
  1982年   6篇
  1981年   4篇
  1979年   8篇
  1970年   7篇
  1968年   3篇
  1966年   6篇
  1965年   3篇
  1935年   4篇
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
21.
22.
Hypoxiaisadirectfactorcausinghypoxicpul monaryhypertension (HPH) .hypoxiainduciblefac tor 1α (HIF 1α)isfoundtobethemostcrucialfactorsofarwhichmediatesthecellularresponsetohypoxi a[1] .OurpreviousstudyrevealedthatoverexpressionofHIF 1andendothelin 1(ET 1…  相似文献   
23.
Certain cytokines such as tumor necrosis factor (TNF) and interleukin-1 (IL-1) act centrally to affect eating behavior and thermoregulation and may be involved in the physiological mechanisms leading to anorexia, adipsia and loss in body weight. The newly discovered macrophage inflammatory protein-1 (MIP-1) infused into the anterior hypothalamic, preoptic area (AH/POA) evokes an intense hyperthermia. The present experiments were designed to determine whether MIP-1 affects the feeding mechanism in the ventromedial hypothalamus (VMH) independently of the thermoregulatory mechanism in the AH/POA. For the microinjection of MIP-1, guide cannulae were implanted stereotaxically in the rat just above the VMH or AH/POA. Following postoperative recovery, each unrestrained rat was adapted to procedures whereby body temperature and intakes of food and water available ad lib were monitored at predetermined intervals. When an efficacious dose of 5.6 picograms (pg) MIP-1 was microinjected in a volume of 0.5 microliters into the VMH, the intake of food in the rat was reduced significantly in the short term and throughout the following 22 h. Within intervals of 30 min and 4.0 h following MIP-1, the amount of food consumed was 4.0 and 10 g, respectively, below that eaten by control rats given the saline solvent vehicle injected at the same site in the VMH. Over the entire test period, the intake of water was similarly significantly below that of the control rats. Whereas MIP-1 injected into the AH/POA evoked fever accompanied by a transient decline in feeding, the body temperature of the rats was unaffected by the cytokine injected in the VMH.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
24.
We have constructed a new capsid-modified adenovirus (Ad) vector that specifically replicates in tumor cells and expresses TNF-related apoptosis-inducing ligand (TRAIL). The Ad capsid contains short-shafted fibers derived from Ad serotype 35, which allow for efficient infection of malignant tumor cells, and largely avoids innate toxicity after intravenous application. Replication-dependent homologous recombination in Ad genomes was used to achieve tumor-specific expression of Ad E1a (to mediate viral replication) and TRAIL (to mediate apoptosis and enhance release of progeny virus from infected cells). We demonstrated that our oncolytic vector (Ad5/35.IR-E1A/TRAIL) induced apoptosis in human tumor cell lines derived from colorectal, lung, prostate, and liver cancer. Both in vitro and in vivo tumor models showed efficient intratumoral spread of this vector. In a model for metastatic colon cancer, tail vein infusion of Ad5/35.IR-E1A/TRAIL resulted in elimination of preestablished liver metastases. Intravenous injection of this vector caused a transient elevation of serum glutamic pyruvic transaminase in tumor-bearing mice, which we attributed to factors released from apoptotic tumor cells. Liver histology analyzed at day 14 after virus injection did not show signs of hepatocellular damage. This new oncolytic vector represents a potentially efficient means for gene therapy of metastatic cancer.  相似文献   
25.
We describe the enhancement patterns of myoepithelioma in two patients with a soft palate mass. In the first case, helical CT revealed a faintly enhancing mass. Histologically, the tumor was composed of plasmacytoid cells in a background of rich myxoid stroma. Immunostaining for CD34 showed scanty blood vessels. In the second case, helical CT revealed an intensely enhancing mass. Histologically, the mass was a cellular tumor with fibrous stroma. Immunostaining for CD34 also showed frequent blood vessels.  相似文献   
26.
王茜  王文亮 《医学争鸣》1996,17(2):94-96
观察双特异性单克隆抗体介导的人单核-巨噬细胞在裸鼠体内对肝癌生长的抑制作用。用化学交联法制备双特异性单克隆抗体HAb18-MAb7及HAb18F(ab)2-MAb7F(ab'_2,并将其与单核-巨噬细胞-同注入荷人肝癌裸鼠体内,观察肿瘤体积的变化。  相似文献   
27.
Obesity in youth and middle age and risk of colorectal cancer in men   总被引:5,自引:0,他引:5  
To investigate an association between colon cancer and obesity during early adulthood—a potentially important period in the etiology of this disease—the authors assembled, by computer linkage, a population-based historical cohort of 52,539 men born between 1913 and 1927 residing in Hawaii (USA), for whom weight and height had been recorded in 1942–43 and 1972. Linkage of this cohort to the Hawaii Tumor Registry resulted in the identification of 737 incident cases of colorectal cancer for 1972–86. An average of 3.8 cancer-free controls were matched to each case on month and year of birth and ethnicity of the parents. A case-control analysis in each anatomic subsite of the large bowel revealed that both early and middle-age body mass increased the risk of sigmoid cancer in men in a dose-dependent fashion. The odds ratios (OR) for sigmoid cancer for the highest compared with the lowest tertiles of Quetelet index were: 2.1 (95 percent confidence interval [CI]=1.4–3.2) and 1.7 (CI=1.1–2.5), at ages 15–29 and in prediagnostic years, respectively. These associations were additive and idependent of socioeconomic status. Men who were above the median Quetelet index in 1942 and 1972 had an OR of 2.7 (CI=1.8–4.0), compared with those who were below the median in both periods. This study provides further evidence for an association of obesity with colon cancer in men and suggests that this association is limited to the sigmoid colon and may be related to both early and late events of colon carcinogenesis.The authors are with the Epidemiology Program, Cancer Research Center of Hawaii, University of Hawaii. Address correspondence to Dr Le Marchand, Epidemiology Program, Cancer Research Center of Hawaii, 1236 Lauhala Street, Suite 407, Honolulu, HI 96813, USA. This work was supported in part by Public Health Service grant 5-R29-CA44503 and contract NO1-CN-55424 from the National Cancer Institute, National Institutes of Health, Department of Health and Human Services.  相似文献   
28.
实验性室间隔缺损心肌血管紧张素Ⅱ受体表达的变化   总被引:1,自引:1,他引:0  
目的 探讨实验性室间隔缺损 ( VSD)动物左右心室心肌血管紧张素 受体的改变。方法 建立猪实验性室间隔缺损动物模型 ,术后 1月取左右心室组织 ,通过放射性配体受体结合分析法测定每 10 6个细胞上血管紧张素 受体 ( AT1 R、AT2 R)的最大结合量 ( Bmax)和平衡解离常数 ( KD)。结果 假手术组与正常组动物受体的 Bmax和KD改变无统计学意义 ,手术组动物左室 AT1 R、右室 AT1 R和 AT2 R的 Bmax值 (分别为 188.42± 13 3 .97、2 72 .14±2 3 2 .74、40 .42± 3 4.76fmol/ 10 6 ,对照组 AT1 R和 AT2 R的 Bmax值左室为 2 9.2 0± 19.5 0和 2 .90± 0 .64 ,右室为76.72± 5 1.2 1和 9.63± 1.2 7fm ol/ L )增高明显 ( P<0 .0 5 )。结论 心内左向右所引起的心室容量负荷过重 ,导致AT1 R的表达增高 ,是 VSD心室肥厚及重构的重要机制 ;AT2 R在右心室表达增高 ,可能是中等程度容量负荷的VSD容易出现左室肥厚而非右室肥厚的原因  相似文献   
29.

Objectives  

To investigate clinical effects and manual operational point of Bryan cervical disc prosthesis in Chinese, to observe the stability and range of movement (ROM) post-operatively.  相似文献   
30.
本文用反复静脉注射小剂量牛血清白蛋白复制家兔慢性肾炎,用羊踯躅根治疗。同时,用该药对慢性肾炎病人进行疗效观察。阳性组兔肾小球呈现中至重度颗粒形免疫荧光,肾组织呈明显慢性硬化性肾小球肾炎改变。尿蛋白±~++。治疗组兔及病人治疗后病变及症状均明显减轻或消失。结果提示循环免疫复合物反复沉着可引起兔类似人类的慢性硬化性肾小球肾炎,羊踯躅根对病变有一定的控制和治疗作用,这可能与其抑制免疫发病机制有关。  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