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   1018篇
  免费   65篇
  国内免费   3篇
耳鼻咽喉   14篇
儿科学   17篇
妇产科学   89篇
基础医学   153篇
口腔科学   29篇
临床医学   87篇
内科学   190篇
皮肤病学   43篇
神经病学   151篇
特种医学   30篇
外科学   114篇
综合类   9篇
一般理论   1篇
预防医学   38篇
眼科学   33篇
药学   24篇
肿瘤学   64篇
  2023年   10篇
  2022年   16篇
  2021年   35篇
  2020年   25篇
  2019年   28篇
  2018年   33篇
  2017年   22篇
  2016年   38篇
  2015年   39篇
  2014年   50篇
  2013年   43篇
  2012年   77篇
  2011年   83篇
  2010年   44篇
  2009年   44篇
  2008年   65篇
  2007年   74篇
  2006年   46篇
  2005年   58篇
  2004年   64篇
  2003年   45篇
  2002年   42篇
  2001年   6篇
  2000年   4篇
  1999年   5篇
  1998年   15篇
  1997年   7篇
  1996年   4篇
  1995年   6篇
  1994年   4篇
  1993年   3篇
  1991年   4篇
  1990年   3篇
  1989年   6篇
  1988年   2篇
  1987年   3篇
  1986年   4篇
  1984年   3篇
  1983年   4篇
  1981年   2篇
  1978年   1篇
  1976年   1篇
  1975年   2篇
  1974年   3篇
  1970年   1篇
  1968年   1篇
  1932年   1篇
  1931年   1篇
  1930年   1篇
  1928年   3篇
排序方式: 共有1086条查询结果,搜索用时 0 毫秒
51.
AIMS: This study asks if repeated Pavlovian pairings of a sipper tube (conditioned stimulus, CS) with food (unconditioned stimulus, US) will induce Pavlovian autoshaping conditioned responses (CRs), consisting of drinking of either 6% ethanol or water from the sipper CS. This study also tests predictions derived from the autoshaping model by asking if sipper CS-directed drinking will be retained, despite the absence of training for several weeks, and, in addition, if drinking rate is a negative function of sipper CS duration. METHODS: Autoshaping procedures, conducted in two daily sessions, consisted of the brief insertion of the sipper tube CS followed by the response-independent presentation of food US. For the Ethanol group (n = 8), the sipper CS contained 6% ethanol, whereas for the Water group (n = 8), the sipper CS contained tap water. Saccharin fading procedures were employed, whereas for both groups, during days 1-19, the sipper CS contained 0.1% saccharin, and thereafter across training days the concentration of saccharin was gradually reduced (0.07, 0.035, 0.0%). Following elimination of saccharin, both groups were maintained in their home cages during a 27-day retention interval, and then re-evaluated for autoshaping of drinking of unsweetened ethanol and water. Thereafter, across days, the duration of access to the sipper CS (5.0, 7.5, 10.0, 15.0 s) during each autoshaping trial was increased. RESULTS: Both groups increased drinking across the first 19 days of training with sipper CS-food US pairings, and, at 0.0% saccharin, the Ethanol group consumed 14.76 ml of 6% ethanol per day, resulting in a daily ethanol consumption of 2.77 g/kg. For both groups, daily levels of drinking before and after the 27-day retention interval were comparable, attesting to the durability of the acquired drinking effects. At each CS duration, the Ethanol group consumed more millilitres of fluid per day than did the Water group, and for the Ethanol group, peak drinking of 24.0 ml of 6% ethanol per day was observed at the 10 s CS duration. For both groups, drinking rate (millilitres of fluid consumed per second of CS duration), was a declining monotonic function of CS duration, resulting in a daily ethanol consumption of approximately 4.2 g/kg for the Ethanol group. CONCLUSIONS: These data reveal that these sipper CS-food US autoshaping procedures induce drinking in rats that is durable and negatively related to increasing CS duration. The effects of both variables are consistent with the hypothesis that drinking from the sipper CS is a Pavlovian autoshaping CR. Autoshaping of drinking in the Water group is observed despite the absence of water deprivation, and even more fluid is consumed by the Ethanol group than by the Water group. The high volumes of ethanol consumed during brief daily sessions suggest that Pavlovian autoshaping procedures may provide an animal learning model of binge drinking.  相似文献   
52.
Although laparoscopic surgery is known to cause less postoperative pain when compared to laparotomy, some patients still suffer from excessive pain, especially during the first stages of recovery. The purpose of our study was to assess the effect of intraperitoneal nebulization of lidocaine during gynecological laparoscopic procedures on perioperative pain. The study was a prospective, randomized, double-blinded, placebo-controlled trial (Canadian task force classification I) that included 23 patients who underwent outpatient gynecological laparoscopic procedures. Patients were randomly assigned either to a study group that received 5 mg/kg of lidocaine intraperitonealy during surgery (n=15) or to a control group that received sterile water in the same manner (n=8). The fluid was infuslated along with the CO2 through a Insuflow® device. All patients received the same anesthetic technique. Intraoperative pain as assessed by changes in the vital signs was treated with fentanyl. Postoperative pain was evaluated according to postoperative opioid requirements and by the Visual Analogue Scale (VAS) at 15 min, 1 h and 24 h postoperatively. The VAS score was found to be lower for the study group 1 h after surgery (p=0.023). There was no difference in the VAS scores at 15 min (p=0.9) and 24 h (p=0.11) after surgery. A correlation analysis showed no association between the amount of lidocaine insufflated and the severity of the postoperative pain. There was no difference in terms of fentanyl administration during surgery or opiod consumption following surgery between the groups. We concluded that continuous intraperitoneal insuflation of lidocaine using an Insuflow® device may significantly reduce pain in the initial stage of postoperative recovery.  相似文献   
53.
Introduction: Our objective was to evaluate the incidence of chromosomal aberration (both microscopic and submicroscopic) and the clinical outcome of fetuses with isolated muscular ventricular septal defect (VSD).

Material and methods: The study included 40 pregnant women whose fetuses were diagnosed with isolated muscular ventricular septal defect (mVSD). Of these, 30 patients underwent amniocentesis and 10 declined. All samples were tested by chromosomal microarray analysis (CMA). Of the 40 women in the study, 32 gave birth and the clinical outcome of the children was retrieved from the patients’ medical records.

Results: Of the 30 patients who underwent amniocentesis, one was detected with mosaic Klinefelter syndrome and one was detected with a pathogenic copy number variant unrelated to the VSD. Clinical follow-up was performed on 26 children after birth. The first postnatal echocardiography did not detect a VSD in 13 (50%) of the followed-up children. Spontaneous closure occurred in another eight (30.8%) children during the postnatal follow-up period. In only five children (19.2%) VSD was still detected by echocardiography after the first year of life.

Discussion: Isolated muscular VSD diagnosed prenatally does not appear to be a significant risk factor for chromosomal abnormalities and has a favorable clinical outcome.  相似文献   

54.
Congenital sacrococcygeal dysplasia is an uncommon though important cause of neuropathic bladder disease leading to progressive renal damage. In 2 cases described herein and featuring long-standing incontinence and recurrent infections, the concomittant musculoskeletal abnormalities had been treated for years, while the urinary tract condition had been largely neglected until urinary diversion or unilateral nephrectomy were required.  相似文献   
55.
To determine the role of the phosphatidylinositol 3-kinase (PI3-K) pathway in pancreas development, we generated a pancreas-specific knockout of Pten, a negative regulator of PI3-K signaling. Knockout mice display progressive replacement of the acinar pancreas with highly proliferative ductal structures that contain abundant mucins and express Pdx1 and Hes1, two markers of pancreatic progenitor cells. Moreover, a fraction of these mice develop ductal malignancy. We provide evidence that ductal metaplasia results from the expansion of centroacinar cells rather than transdifferentiation of acinar cells. These results indicate that Pten actively maintains the balance between different cell types in the adult pancreas and that misregulation of the PI3-K pathway in centroacinar cells may contribute to the initiation of pancreatic carcinoma in vivo.  相似文献   
56.
57.
58.
59.
Learned irrelevance (LIrr) is a pre-exposure effect in which uncorrelated presentations of a conditioned stimulus (CS) and an unconditioned stimulus (US) retard subsequent CS-US association. LIrr is closely related to the phenomenon of latent inhibition (LI). LI refers to the retarding effects of inconsequential stimulus pre-exposure on subsequent conditioning to that stimulus, and is considered to reflect the organism's capacity to ignore irrelevant stimuli. LI is disrupted in schizophrenia patients, due to faster learning of the association between the preexposed CS and the US. A new within-subject target-recognition LIrr procedure was applied. The target was either cued by a priming signal or appeared at random, and priming signals were novel or preexposed cues. Schizophrenia patients were compared to age- and sex-matched control subjects. Normal subjects (n = 24) have shown robust LIrr, namely, faster cue-target associations of novel compared to preexposed cues. Schizophrenia patients at the early stages of their first episode (n = 7) showed LIrr disruption, namely, cue-target associations to preexposed cues were as fast as for novel cues. Chronic patients during an acute phase (n = 18) did not show LIrr as they failed to learn the cue-target association. In addition to the LIrr paradigm the same subjects were tested in a covert-orientation task. No differences were observed between the groups on this task. The possible advantages of the new LIrr paradigm are discussed.  相似文献   
60.
A 70.9% majority of the U.S. male veterans in a nationwide sample appraised the impact of their service in Vietnam on their present lives as mainly positive. A substantial minority, 41.7%, judged the effects to be highly salient. With controls on level of exposure to war-zone stressors measured with data from military records, the valence and salience of these appraisals are investigated in relation to posttraumatic stress disorder (PTSD) and other indicators of wartime and postwar functioning. The results are consistent with the hypothesis that mainly positive tertiary appraisals are affirmations of successful wartime and postwar adaptation rather than defensive denials related to maladaptive outcomes. The possibility that mainly positive tertiary appraisals also contribute to successful postwar adaptation is discussed.  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