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   649篇
  免费   45篇
  国内免费   10篇
耳鼻咽喉   10篇
儿科学   6篇
妇产科学   17篇
基础医学   92篇
口腔科学   5篇
临床医学   80篇
内科学   117篇
皮肤病学   6篇
神经病学   68篇
特种医学   16篇
外国民族医学   1篇
外科学   47篇
综合类   37篇
预防医学   55篇
眼科学   11篇
药学   53篇
  3篇
中国医学   16篇
肿瘤学   64篇
  2023年   11篇
  2022年   11篇
  2021年   33篇
  2020年   29篇
  2019年   38篇
  2018年   22篇
  2017年   18篇
  2016年   18篇
  2015年   34篇
  2014年   25篇
  2013年   35篇
  2012年   46篇
  2011年   49篇
  2010年   37篇
  2009年   32篇
  2008年   43篇
  2007年   35篇
  2006年   33篇
  2005年   24篇
  2004年   21篇
  2003年   35篇
  2002年   14篇
  2001年   6篇
  2000年   3篇
  1999年   7篇
  1998年   4篇
  1997年   4篇
  1996年   5篇
  1995年   6篇
  1994年   1篇
  1993年   1篇
  1992年   6篇
  1990年   3篇
  1989年   4篇
  1988年   4篇
  1987年   2篇
  1985年   1篇
  1979年   1篇
  1978年   1篇
  1967年   1篇
  1966年   1篇
排序方式: 共有704条查询结果,搜索用时 312 毫秒
1.
Three hypotheses for cognitive deficits among psychopaths were tested: executive dysfunction, left hemisphere activation, and an interaction between the two. Twenty-one psychopathic and 23 nonpsychopathic criminal offenders identified with the Hare Psychopathy Checklist-Revised participated in verbal and visual-spatial tasks during which the level of executive processing demands was manipulated. Consistent with prior research, psychopathic offenders made more errors than controls, but only during the verbal task and only on trials with high executive demand. Within those trials, most errors occurred when set-maintenance demands were the highest. No response latency differences between groups were found.  相似文献   
2.
Three patients with lymphoid interstitial pneumonia (two HIV 1+ patients with chronic lymphadenopathic syndromes and one with a not-characterized autoimmune disease) have been studied with high-resolution computed tomography (HR-CT). This technique reveals septal lines, small reticulonodular opacities, polyhedral micronodular opacities, "ground-glass" opacities and a dense, subpleural, curved broken line in one patient. The lesions dominate in the bases of the lungs. They are not characteristic for lymphoid interstitial pneumonia. If a patient present with a chronic lymphadenopathic syndrome, the diagnosis of an opportunistic infection should not be automatically made, since the syndrome can be caused by lymphoid interstitial pneumonia.  相似文献   
3.
将昆明小鼠随机分为低(0.025)、中(0.05)、高(0.1)剂量组及生理盐水对照组,以2号海洛因经腹腔注射染毒,20天后,取睾丸组织制成石蜡切片.HE染色,光镜下观察生精小管上皮细胞的形态变化,并应用图像分析系统对初级精母细胞的形态参数进行了分析;结果表明,(1)光镜观察 对照组及低剂量组小鼠睾丸组织未见明显的变化;中剂量组小鼠睾丸曲细精管上皮有不同程度的组织改变;高剂量组小鼠生精管壁细胞明显地出现上皮层次减少,精子细胞和精子减少,并发现曲细精管内有脱落的生精细胞;(2)形态定量分析显示 低剂量组及中剂量组各形态参数(中剂量组圆形度除外)较对照组无显著差异;高剂量组初级精母细胞核面积、核灰度与对照组相比无显著差异,细胞面积、细胞周长及浆面积较对照组明显增大(P<0.05).而核浆比例、圆形度较对照组有减小(P<0.05).结果提示 海洛因可明显改变小鼠生殖细胞的形态结构.  相似文献   
4.
Summary Eight cosmid clones were regionally assigned to small subregions of chromosome 22 by hybridization with a total of 22 somatic cell hybrids. One cosmid was localized to the proximal part of 22q which contained the region commonly deleted in the DiGeorge syndrome. Seven cosmids showing restriction fragment length polymorphisms were localized to the telomeric region distal to the MB locus, which was reported to be frequently deleted in sporadic meningioma. These cosmids, when finely mapped and ordered, are considered useful for the identification of genetic alterations on this chromosome arm.  相似文献   
5.
The ultrastructure of the mature spermatozoon and the spermiogenesis of a cestode belonging to the family Metadilepididae is described for the first time. The mature spermatozoon of Skrjabinoporus merops is characterized by twisted peripheral microtubules, the presence of a single crested body, periaxonemal sheath and electron-dense rods, and the absence of intracytoplasmic walls and inclusions (glycogen or proteinaceous granules); no peripheral microtubules where nucleus contacts the external plasma membrane. Four morphologically distinct regions of the mature spermatozoon are differentiated. The proximal part (Region I) contains a single crested body, periaxonemal sheath is absent in some (proximal) sections and is present in others situated closer to the nucleus. The central Region II is nucleated, and is followed by Region III that contains a periaxonemal sheath. The distal pole, Region IV, is characterized by disintegration of the axoneme. Spermiogenesis follows the type III pattern (Ba and Marchand 1995) although in S. merops a slight flagellar rotation is observed. The differentiation zone is characterized by the absence of striated roots and intercentriolar body; two centrioles are present, one of which gives rise to a free flagellum. The latter rotates and undergoes proximodistal fusion with the cytoplasmic protrusion of the differentiation zone. Spermiological characters of S. merops are similar to those of the families Taeniidae and Catenotaeniidae. The mature spermatozoon differs from those of the Dilepididae (where the metadilepidid species have previously been classified) by the lack of glycogen.  相似文献   
6.
This study elucidates the role of cell volume in contractions of endothelium-denuded vascular smooth muscle rings (VSMR) from the rat aorta. We observed that hyposmotic swelling as well as hyper- and isosmotic shrinkage led to VSMR contractions. Swelling-induced contractions were accompanied by activation of Ca2+ influx and were abolished by nifedipine and verapamil. In contrast, contractions of shrunken cells were insensitive to the presence of L-type channel inhibitors and occurred in the absence of Ca2+o. Thirty minutes preincubation with bumetanide, a potent Na+,K+,Cl cotransport (NKCC) inhibitor, decreased Cli content, nifedipine-sensitive 45Ca uptake and contractions triggered by modest depolarization ([K+]o=36 mM). Elevation of [K+]o to 66 mM completely abolished the effect of bumetanide on these parameters. Bumetanide almost completely abrogated phenylephrine-induced contraction, partially suppressed contractions triggered by hyperosmotic shrinkage, but potentiated contractions of isosmotically shrunken VSMR. Our results suggest that bumetanide suppresses contraction of modestly depolarized cells via NKCC inhibition and Cli-mediated membrane hyperpolarization, whereas augmented contraction of isosmotically shrunken VSMR by bumetanide is a consequence of suppression of NKCC-mediated regulatory volume increase. The mechanism of bumetanide inhibition of contraction of phenylephrine-treated and hyperosmotically shrunken VSMR should be examined further.  相似文献   
7.
目的探讨TG、FPG及TG葡萄糖乘积指数(TyG)与高血压发病间的关系,为人群高血压的防治提供基础数据。方法以金昌队列中符合研究标准的23581人作为研究对象,运用Cox比例风险模型研究TG、FPG及TyG与高血压发病风险间的关系,并按性别进行分层分析。结果在调整混杂因素后,与正常TG组相比,总人群中TG边缘升高组和升高组的HR值(95%CI)分别为1.16(1.01~1.34)和1.49(1.30~1.70),男性中分别为1.13(1.01~1.27)和1.17(1.06~1.30),女性中分别为1.05(0.88~1.26)和1.06(0.88~1.28);与正常FPG组相比,总人群中空腹血糖受损组的HR值(95%CI)为1.29(1.13~1.48),男性中为1.26(1.08~1.48),女性中为1.59(1.14~2.21);以最低四分位数组为参照,总人群中TyG的最高四分位数组的HR值(95%CI)为1.73(1.45~2.07),男性中为1.32(1.14~1.53),女性中为1.87(1.37~2.54)。TG、FPG与高血压发病风险间呈非线性的剂量反应关系,TyG与高血压发病风险线性相关。结论较高的TG、FPG、TyG是高血压发病的独立危险因素,TG、FPG及TyG较高的人群为高血压的高危人群,在高血压防治中应予以重视。  相似文献   
8.
(E)-2-deoxy-2-(fluoromethylene)cytidine (FMdC), one of the most potent inhibitors of ribonucleoside diphosphate reductase, was selected for clinical development because of its novel mechanisms of action, and strong antitumor activity against experimental tumor models. This study was designed to determine the toxicities, maximum-tolerated dose (MTD), and pharmacokinetic profile of FMdC. FMdC was given orally for 5 consecutive days every 3 or 4 weeks in patients with advanced solid tumors. The starting dose was 8 mg/m2/day. Pharmacokinetic studies were carried out on days 1 through 5 of the first cycle. Ten patients with non-small cell lung cancer received 15 courses of FMdC at doses which were de-escalated from 8 mg/m2/day to 2 mg/m2/day because of unexpected severe toxicities at the starting dose level. Neutropenia was the dose-limiting toxicity. Thrombocytopenia and anemia were mild. Flu-like symptoms and fever were the common non-hematologic toxicities. The MTD was 4 mg/m2/day, since four of six patients developed grade 3–4 neutropenia. At the 4 mg/m2/day dose level, the mean terminal half-life, maximum plasma concentration (Cmax), plasma clearance, and mean residence time on day 1 were 3.20 h, 15.8 ng/ml, 2.91 l/h/kg, and 4.03 h, respectively. The recommended dose for phase II studies with this schedule is also 4 mg/m2/day for 5 days. Further investigations are necessary to establish optimal dosing schedules and routes for the administration of FMdC.  相似文献   
9.
10.
The present study examined the relationship between memory and orientation to time, place, and personal and general information, as moderated by age, education, and simple attentional ability. A heterogeneous sample of 312 clinical referrals was divided into four groups, according to delayed memory functioning. Patients with globally good, globally poor, poor visual, and poor auditory memory were at differential risk of being disoriented, with the globally poor memory patients having the greatest risk. Overall, poorly oriented patients were older and less educated, with worse recall of digits backward. Discriminant Function Analysis selected visual and auditory memory and age as predictors of orientation. Normative tables stratified by age and memory performance are presented.  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