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   17399篇
  免费   1318篇
  国内免费   39篇
耳鼻咽喉   160篇
儿科学   639篇
妇产科学   500篇
基础医学   2354篇
口腔科学   208篇
临床医学   2578篇
内科学   2991篇
皮肤病学   188篇
神经病学   1946篇
特种医学   401篇
外科学   1315篇
综合类   235篇
一般理论   37篇
预防医学   2565篇
眼科学   348篇
药学   976篇
中国医学   7篇
肿瘤学   1308篇
  2023年   128篇
  2022年   181篇
  2021年   379篇
  2020年   227篇
  2019年   355篇
  2018年   419篇
  2017年   315篇
  2016年   338篇
  2015年   415篇
  2014年   558篇
  2013年   869篇
  2012年   1175篇
  2011年   1260篇
  2010年   689篇
  2009年   576篇
  2008年   1107篇
  2007年   1173篇
  2006年   1205篇
  2005年   1149篇
  2004年   1022篇
  2003年   973篇
  2002年   988篇
  2001年   150篇
  2000年   129篇
  1999年   150篇
  1998年   211篇
  1997年   158篇
  1996年   136篇
  1995年   118篇
  1994年   130篇
  1993年   127篇
  1992年   92篇
  1991年   71篇
  1990年   82篇
  1989年   74篇
  1988年   68篇
  1987年   58篇
  1986年   74篇
  1985年   74篇
  1984年   82篇
  1983年   69篇
  1982年   97篇
  1981年   71篇
  1980年   88篇
  1978年   64篇
  1977年   57篇
  1976年   46篇
  1975年   53篇
  1974年   48篇
  1973年   54篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Surgeons are privileged to offer treatments that often cure disease. Optimizing comfort for those who cannot be cured is also a core part of every clinician's duty: surveys repeatedly tell us that when death is approaching, people value quality of life above length of survival. Recognizing when someone is dying can be difficult. Tools exist to help; it is worth noting that emergency presentation with life-threatening symptoms can be a marker of poor prognosis. Clear, effective communication is crucial: understanding the patient's perspective and expectations is vital before attempting to offer information that allows future care planning. Judicious use of surgery combined with careful prescribing will optimize comfort, allowing the patient to live as well as possible for as long as possible. Anticipatory prescribing includes opioid, anti-emetic, anti-secretory and sedative medication. Attention should also be given to care of the bereaved. Generalists should understand when to refer to specialist palliative care and remember that reflecting on care when someone has died can be beneficial for professional wellbeing.  相似文献   
82.
83.
84.
85.
This paper explores the potential contribution of timebanking, an innovative volunteering scheme, to the co-production of preventive social care with adults in England. Interest in volunteering in social care has increased as one proposed solution to the international crisis of a rising demand for services in juxtaposition with decreased resources. Volunteering has been particularly promoted in preventive services that prevent or delay care needs arising. Despite sustained interest in volunteering and co-production in social care, little is known about how theory translates into practice. Reporting implementation data from a Realistic Evaluation of six case studies in England, this paper explores one volunteering scheme, timebanking. The research explores how timebanks were working, what contribution they can make to adult social care, and whether they are an example of co-production. Data collected included interviews, focus groups or open question responses on surveys from 84 timebank members, and semi-structured interviews with 13 timebank staff. Each timebank was visited at least twice, and all timebank activity was analysed for a period of 12 months. Data were triangulated to improve reliability. The research found that in practice, timebanks were not working as described in theory, there were small numbers of person-to-person exchanges and some timebanks had abandoned this exchange model. Timebanks faced significant implementation challenges including managing risk and safeguarding and the associated bureaucracy, a paternalistic professional culture and the complexity of the timebank mechanism which required adequate resources. Lessons for timebanks are identified, as well as transferable lessons about co-production and volunteering in social care if such schemes are to be successful in the future.  相似文献   
86.
Are androgens reinforcing? Androgenic-anabolic steroids (AAS) are drugs of abuse. They are taken in large quantities by athletes and others to increase performance, often with negative long-term health consequences. As a result, in 1991, testosterone was declared a controlled substance. Recently, Brower [K.J. Brower, Anabolic steroid abuse and dependence. Curr. Psychiatry Rep. 4 (2002) 377-387.] proposed a two-stage model of AAS dependence. Users initiate steroid use for their anabolic effects on muscle growth. With continued exposure, dependence on the psychoactive effects of AAS develops. However, it is difficult in humans to separate direct psychoactive effects of AAS from the user's psychological dependence on the anabolic effects of AAS. Thus, studies in laboratory animals are useful to explore androgen reinforcement. Testosterone induces a conditioned place preference in rats and mice, and is voluntarily consumed through oral, intravenous, and intracerebroventricular self-administration in hamsters. Active, gonad-intact male and female hamsters will deliver 1 microg/microl testosterone into the lateral ventricles. Indeed, some individuals self-administer testosterone intracerebroventricularly to the point of death. Male rats develop a conditioned place preference to testosterone injections into the nucleus accumbens, an effect blocked by dopamine receptor antagonists. These data suggest that androgen reinforcement is mediated by the brain. Moreover, testosterone appears to act through the mesolimbic dopamine system, a common substrate for drugs of abuse. Nonetheless, androgen reinforcement is not comparable to that of cocaine or heroin. Instead, testosterone resembles other mild reinforcers, such as caffeine, nicotine, or benzodiazepines. The potential for androgen addiction remains to be determined.  相似文献   
87.
The involvement of the immediate-early (IE) genes c-fos, c-jun,and c-myc in regenerative liver hyperplasia is accepted, buttheir involvement in direct hyperplasia is uncertain. We haveexamined the hypothesis that the ability to induce IE genesmay reflect the hepatocarcinogenic potential of a chemical.The ability of 1,4-dichlorobenzene (DCB) (300 mg/kg) (a noncarcinogemcrat liver mitogen), diethylhexyl phthalate (DEHP) (950 mg/kg),and chlorendic acid (120 mg/kg) (both nongenotoxic hepatocarcinogens)to induce c-fos, c-jun. and c-myc expression in rat liver wasdetermined by Northern blot analysis and by in situ hybridization.Results were correlated to hepatic labeling index (LI) as determinedby incorporation of BrdU in each of three lobes for each ofthree male F344 rats per group. Carbon tetrachioride (CCl4 (2ml/kg) was used as a positive control. Increased LI was precededby elevated expression of all three IE genes after CCl4., butalso after DCB and DEHP, although induction by these was lessmarked. In all cases, there was considerable interanimal variationwithin groups, but little interlobe variation. Interestingly,there was a good correlation (r2 0.85) between c-myc expressionand LI, but not between LI and c-fos or c-jun. Despite the disparatecarcinogenic potential of DEHP and DCB, both chemicals inducedsimilar patterns of IE gene expression, suggesting that thiscannot distinguish hepatocarcinogenic liver mitogens from noncarcinogenicliver mitogens. These data assist in the evaluation of IE geneexpression both as a marker of direct versus regenerative hyperplasiaand as an indicator of the hepatocarcinogenic potential of livermitogens.  相似文献   
88.
89.
90.
Tailoring Antireflux Surgery: A Randomized Clinical Trial   总被引:6,自引:0,他引:6  
A hypothesis has been formulated that mandates the adjustment of antireflux surgery to either a total or a partial wrap depending on the motor function of the esophagus to avoid dysphagia and other obstructive complaints. This hypothesis has been tested in a randomized, clinical trial where 106 chronic gastroesophageal reflux patients were allocated to either a total Nissen-Rossetti (n= 53) or a Toupet partial posterior (n= 53) fundoplication, irrespective of their preoperative esophageal motor function. All patients were followed at least 3 years, during which time none had a relapse of moderate to severe reflux symptoms. Motor dysfunctions defined as peristaltic amplitude ≤ 30 mmHg in the distal third and failed primary peristalsis with or without > 20% simultaneous contractions were noted in 67 patients preoperatively, but these patients did not have a specific symptom profile (e.g., dominated by obstructive symptoms) nor did seven patients with “aperistaltic esophagus.” The incidence of dysphagia decreased from 20% preoperatively to 8% (mild) at 3 years after the operation with no difference between the surgical procedures. We were unable to demonstrate a relation between preoperative manometric findings and postoperative symptoms when assessed in the total group or when subdivided by the type of fundoplication (r < 0.3). Flatulence occurred more frequently among those with a total fundic wrap (p < 0.01). When patients representing motor dysfunction (see above) were specifically analyzed, we again observed no difference in outcome between those having a total or a partial fundic wrap. In conclusion, the concept of tailoring antireflux surgery based on the preoperative motor function of the esophagus in patients with chronic gastroesophageal reflux disease was not supported by the results of this clinical trial.  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