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   529篇
  免费   26篇
  国内免费   12篇
耳鼻咽喉   4篇
儿科学   13篇
妇产科学   5篇
基础医学   55篇
口腔科学   43篇
临床医学   59篇
内科学   128篇
皮肤病学   9篇
神经病学   27篇
特种医学   98篇
外科学   41篇
综合类   19篇
预防医学   21篇
眼科学   2篇
药学   22篇
中国医学   1篇
肿瘤学   20篇
  2023年   8篇
  2022年   9篇
  2021年   9篇
  2020年   7篇
  2019年   7篇
  2018年   7篇
  2017年   6篇
  2016年   11篇
  2015年   6篇
  2014年   8篇
  2013年   19篇
  2012年   8篇
  2011年   12篇
  2010年   18篇
  2009年   28篇
  2008年   7篇
  2007年   21篇
  2006年   4篇
  2005年   3篇
  2004年   9篇
  2003年   5篇
  2002年   9篇
  2001年   8篇
  1999年   7篇
  1998年   30篇
  1997年   30篇
  1996年   30篇
  1995年   26篇
  1994年   19篇
  1993年   19篇
  1992年   10篇
  1991年   8篇
  1990年   14篇
  1989年   17篇
  1988年   17篇
  1987年   22篇
  1986年   9篇
  1985年   5篇
  1984年   8篇
  1980年   3篇
  1977年   6篇
  1976年   4篇
  1975年   9篇
  1972年   2篇
  1970年   2篇
  1966年   2篇
  1933年   4篇
  1932年   3篇
  1931年   9篇
  1930年   6篇
排序方式: 共有567条查询结果,搜索用时 15 毫秒
1.
2.
3.
Usher syndrome is recognized as the most frequent cause of hereditary deaf-blindness. Usher syndrome type I (USH1), the most severe form of the disease, is characterized by profound congenital sensorineural deafness, constant vestibular dysfunction, and retinitis pigmentosa of prepubertal onset. This form is genetically heterogeneous and five loci (USH1A-E) have been mapped thusfar. However, only the gene responsible for USH1 B (which accounts for approximately 75% of USH1 cases) has been characterized. It encodes a long-tailed unconventional myosin, myosin VIIA, with a predicted 2215 amino acid sequence. Primers covering the complete myosin VIIA coding sequence as well as the 3' non coding sequence were designed, allowing direct sequence analysis of each of the 48 coding exons and flanking splice sites in seven patients affected by USH1. Four novel mutations were thereby identified. The possibility should now be considered of a sequence-based prenatal diagnosis in some of the families affected by this very severe form of Usher syndrome.   相似文献   
4.
5.
Evolutionary silencing of the human elastase I gene (ELA1)   总被引:6,自引:0,他引:6  
  相似文献   
6.
PurposeWe aimed to assess the prognostic value of Neutrophil to Lymphocyte Ratio (NLR) on long-term outcomes and graft dysfunction after lung transplantation.MethodsWe retrospectively reviewed all patients receiving a lung transplant at our institution from 2011 to 2014. The primary exposure was elevated NLR at the time of transplant, defined by NLR>4. The primary outcomes were graft failure and three-year all-cause mortality. Multivariate logistic regression and Kaplan-Meier survival analysis were used to analyze outcomes.Results95 patients were included. 40 patients (42%) had an elevated NLR. Elevated NLR was associated with graft failure (OR: 4.7 [1.2–18.8], p = 0.02), and three-year mortality (OR: 5.4 [1.3–23.2], p = 0.03) on multivariate logistic regression. Patients with elevated NLR demonstrated significantly lower survival on Kaplan-Meier analysis (50% versus 74%, p = 0.02). The c-statistic for our multivariate model was 0.91.ConclusionElevated neutrophil to lymphocyte ratio is associated with poor long-term survival and graft failure after lung transplantation.  相似文献   
7.
Eighty-three male alcoholics were administered a structured interview when they appeared at a large general hospital for treatment of a variety of disorders. These represent 83 consecutive cases. None received treatment aside from brief "drying-out" but all were accepted as participants in a research program. Seventy-three (88 per cent of the sample) were located for a 3-year follow-up; five of these were not seen at the 1-year follow-up, and 10 were known to be dead. This paper focuses on 58 of the alcoholics who were seen at all three evaluations, and the 10 who were known dead. The data are presented as indicating the long term results of, at best, a mild or minimal intervention with male alcoholics. A small, but significant improvement was noted on several life-adjustment scales between the initial and 1-year evaluation (OYE), but no further improvement was seen between OYE and the 3-year evaluation (TYE); 19 percent were abstinent for 1 year and 10 per cent for the full 3-year period. The best predictor of TYE abstinence was OYE abstinence, but only for the extremes, i.e., no abstinence or total abstinence. Abstinence success was also related to a tendency to use community resources, lower number of mental hospitalizations, higher occupational status, higher global rating and, curiously, lower interpersonal adjustment rating. The group using Alcoholics Anonymous showed no better outcome than the group using no community resources at all. The mortality rate was 12 per cent over the 3 years or slightly more than 4 per cent a year. The suicide rate was about 4 per cent over the 3 years. The ratings for those dying showed a pattern of more admitted drunken arrests and heavy recent drinking superimposed on lighter overall drinking for the past year. The study demonstrates that even untreated alcoholics can be traced and effective follow-up studies completed. Results also indicate that over long time periods and left to their own devices, many alcoholics do seek out some form of help. But such assistance tends not to be sustained or intensive and a good portion of it is nonprofessional and nonmedical. Moreover, a surprisingly substantial number (31 per cent) of hospital-identified alcoholics apparently neither seek out nor receive any help at all after their initial identification; yet their self-reported life-adjustment ratings do not differ significantly from those who do seek help. The no-help receivers may be the most critical group of all to follow, as they are trule untreated. It would be important to determine how consistent in fact they are in their avoidance of help, what accounts for that behavior, and whether their ultimate fate is different from those who regularly seek assistance.  相似文献   
8.
OBJECTIVE: To compare the effectiveness of three new topical anesthetics that do not contain cocaine (prilocaine-phenylephrine, tetracaine-phenylephrine [tetraphen], and tetracaine-lidocaine-phenylephrine) to that of tetracaine-adrenaline-cocaine (TAC) during laceration repair in children. DESIGN: Prospective, randomized, double-blind clinical trial. SETTING: The emergency department of an urban children's hospital. PARTICIPANTS: Children 1 year of age or older with a laceration /= 5 years of age using a visual analogue scale (VAS). Suture technicians, research assistants, and parents also scored pain using a seven-point Likert scale. In addition, suture technicians completed an anesthetic effectiveness scale. RESULTS: There was consistently no difference demonstrated between the effectiveness of tetraphen and that of TAC for each outcome measure of each observer group. A statistically significant difference was seen among anesthetics when comparing VAS and Likert scale scores of suture technicians and Likert scale scores of research assistants. Based on post hoc analyses, these statistically significant differences were between TAC and prilocaine-phenylephrine (suture technician VAS and Likert scale) and between TAC and tetracaine-lidocaine-phenyl-ephrine (suture technician Likert scale), but not between TAC and tetraphen. When power analyses were performed using alpha = 0.05 and beta = 0.20, it was possible to detect a difference of 1.2 VAS units for each of the observer groups. Based on anesthetic effectiveness scale scores, the three new topical preparations collectively performed significantly better on the face and scalp than on the extremities (relative risk = 1.83; 95% confidence interval 1.20 < relative risk < 2.79). CONCLUSION: This study demonstrated the effectiveness and safety of three new non-cocaine-containing topical anesthetics. Consistently, there was no statistical difference demonstrated between the effectiveness of tetraphen and that of TAC for each outcome measure of each observer group. Tetraphen offers an effective alternative to TAC during laceration repair in children.  相似文献   
9.
Non-typhoid Salmonella gastroenteritis   总被引:2,自引:0,他引:2  
  相似文献   
10.
Lytton  SD; Mester  B; Libman  J; Shanzer  A; Cabantchik  ZI 《Blood》1994,84(3):910-915
Iron chelation treatment of red blood cells infected with Plasmodium falciparum selectively intervenes with iron-dependent metabolism of malaria parasites and inhibits their development. Highly permeant hydroxamate iron chelator RSFileum2 affects all parasite stages when cultures are continuously exposed to drug, but affects primarily ring stages when assessed for irreversible effects, ie, sustained inhibition remaining after drug removal. On the other hand, the hydrophilic and poorly permeant desferrioxamine (DFO) affects primarily trophozoite/schizont stages when tested either in the continuous mode or irreversible mode. Unlike parasites, mammalian cells subjected to similar drug treatment show complete growth recovery once drugs are removed. Our studies indicate that parasites display a limited capacity to recover from intracellular iron depletion evoked by iron chelators. Based on these findings we provide a working model in which the irreversible effects of RSFs on rings are explained by the absence of pathways for iron acquisition/utilization by early forms of parasites. Trophozoite/schizonts can partially recover from RSFileum2 treatments, but show no DNA synthesis following DFO treatment even after drug removal and iron replenishment by permeant iron carriers. At trophozoite stage, the parasite uses a limited pathway for refurnishing its iron-containing enzymes, thus overcoming iron deprivation caused by permeant RSFileum2, but not by DFO because this latter drug is not easily removable from parasites. Their DNA synthesis is blocked by the hydroxamate iron chelators probably by affecting synthesis of ribonucleotide reductase (RNRase). Presumably in parasites, prolonged repression of the enzyme leads also to irreversible loss of activity. The action profiles of RSFileum2 and DFO presented in this study have implications for improved chemotherapeutic performance by combined drug treatment and future drug design based on specific intervention at parasite DNA synthesis.  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