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   2909篇
  免费   165篇
  国内免费   8篇
耳鼻咽喉   32篇
儿科学   90篇
妇产科学   73篇
基础医学   456篇
口腔科学   60篇
临床医学   386篇
内科学   474篇
皮肤病学   56篇
神经病学   297篇
特种医学   264篇
外科学   275篇
综合类   19篇
预防医学   162篇
眼科学   37篇
药学   240篇
中国医学   1篇
肿瘤学   160篇
  2021年   29篇
  2020年   29篇
  2019年   34篇
  2018年   52篇
  2017年   38篇
  2016年   64篇
  2015年   82篇
  2014年   78篇
  2013年   74篇
  2012年   120篇
  2011年   127篇
  2010年   94篇
  2009年   100篇
  2008年   129篇
  2007年   117篇
  2006年   111篇
  2005年   101篇
  2004年   95篇
  2003年   109篇
  2002年   84篇
  2001年   83篇
  2000年   96篇
  1999年   59篇
  1998年   65篇
  1997年   34篇
  1996年   36篇
  1995年   30篇
  1994年   30篇
  1993年   28篇
  1992年   66篇
  1991年   49篇
  1990年   63篇
  1989年   70篇
  1988年   56篇
  1987年   54篇
  1986年   65篇
  1985年   53篇
  1984年   27篇
  1983年   31篇
  1982年   19篇
  1981年   19篇
  1979年   29篇
  1978年   25篇
  1977年   30篇
  1976年   24篇
  1975年   18篇
  1973年   18篇
  1972年   18篇
  1971年   21篇
  1970年   18篇
排序方式: 共有3082条查询结果,搜索用时 15 毫秒
1.
2.
In 41 patients with recurrent sustained ventricular tachycardia and/or ventricular fibrillation an integrated pacemaker-defibrillator-system (PCD, Medtronic, model 7216 A or 7217 B) was implanted. In 21 out of 24 (88%) patients a new transvenous implantation technique in combination with a subcutaneous patch electrode was used. The implanted devices comprise antibradycardiac pacemaker functions, two different forms of antitachycardiac pacemaker functions (ramp and burst pacing), and internal cardioversion or defibrillation capabilities. During a mean follow-up of 8 months 147 episodes of ventricular tachycardia were detected, 131 of them were terminated successfully by antitachycardiac pacing; in 13 episodes internal cardioversion was applied to revert ventricular tachycardia. Twenty-seven episodes of ventricular fibrillation or rapid ventricular tachycardia (greater than 200/min) were detected and successfully terminated by internal defibrillation. In six patients with intermittent rapid atrial fibrillation, change of antiarrhythmic therapy was required to avoid activation of the device. The new integrated pacemaker-defibrillator systems improve therapy in patients with life-threatening tachyarrhythmias by reducing the number of internal cardioversions/defibrillations; the non-thoracotomy approach reduces the post operative risk.  相似文献   
3.
Patient history and clinical examination are important for the diagnosis of degenerative joint disease. Here the typical statements of a patient suffering from early osteoarthritis are described and, as far as possible, explained. The joint in question must be systematically examined. Furthermore, the neighboring joints and soft-tissue structures, i.e., muscles, tendons etc., should be examined and evaluated with respect to their importance in hindering the functional chain. The neuroreflectory mechanisms involved herein are described.  相似文献   
4.
The dose of nicotine and the frequency of its administration appear to be essential determinants of its action on multiple systems including the neuroendocrine regulation of the adrenocorticotropin (ACTH)-corticosterone and prolactin (PRL) axes in the rat. Because desensitization to the acute depressive effects of nicotine has been observed after both acute and chronic administration, these investigations assessed whether desensitization to the stimulative effects of nicotine on ACTH and PRL secretion occurs with repetitive dosing. Extensive dose and time course experiments showed that nicotine rapidly elevates rat plasma ACTH and PRL levels with a threshold dose between 0.1 to 0.25 mg/kg b.wt. i.p. After the stimulation of PRL, levels became significantly depressed. Desensitization to the acute stimulatory effects of nicotine on both hormones was induced by a single dose of nicotine (0.5 mg/kg). One hour later nicotine (1.0 mg/kg) failed to significantly stimulate PRL levels and resulted in a modest increase of ACTH. Desensitization was maximal by 1 hr after the first dose and persisted for at least 6 hr. Adrenalectomy, performed to eliminate corticosterone-induced negative feedback, did not enhance PRL responsiveness to a second dose of nicotine but it partially restored the ACTH response. Pretreatment with corticosterone also failed to modify the PRL response to a single dose of nicotine whereas it partially suppressed the ACTH response. Rapid desensitization to the acute stimulatory effects of nicotine on plasma PRL is independent of glucocorticoid negative-feedback whereas desensitization of the ACTH response is modestly dependent.  相似文献   
5.
6.
Background/aim  Theoretical considerations support the combination of cryosurgery and topical imiquimod to treat basal cell carcinomas (BCC). The aim of the present study was to test the feasibility and efficacy of 'cryosurgery during continued imiquimod application' ('immunocryosurgery') to treat 'high-risk-for-recurrence' BCCs.
Methods  Thirteen patients with 21 biopsy-proven tumours (4 of 21 relapses after prior surgery) were included. After 2–5 weeks (median, 3) of daily 5% imiquimod cream application, the tumours were treated by liquid N2 cryosurgery (spray, two cycles, 10–20 s) and imiquimod was continued for additional 2–12 weeks (median, 4). The outcome after at least 18 months of follow-up (18–24 months) is currently reported.
Results  Nineteen of 21 tumours responded promptly to immunocryosurgery; two tumours required additional treatment cycles to clear. Thus, the clinical clearance rate was 100%. Only 1 of 21(5%) tumour relapsed after at least 18 months of follow-up (cumulative efficacy: 95%).
Conclusions  'Immunocryosurgery' is a promising non-surgical combination modality to treat 'high-risk-for-recurrence BCCs'. Initial evidence is suggestive of an at least additive effect of the two combined modalities. Further studies comparing immunocryosurgery directly with cryosurgery and imiquimod monotherapies will confirm the reported results.  相似文献   
7.
In tube-fed patients, dietary fiber is often used to manage constipation/diarrhea. Dietary fiber consists of water-soluble and insoluble plant compounds that are resistant to digestion by small-bowel enzymes but are fermented to varying degrees by colonic bacteria. Many physiologic effects of fiber may be related to the degree of fermentation. Few controlled studies of fiber-containing tube feedings have been performed. These studies have limitations and are nondefinitive as to whether fiber prevents or controls constipation/diarrhea. Constipation in tube-fed patients has not been shown to respond to mixed soluble/insoluble fiber in the few studies performed to date. Likewise, fiber may be of only limited benefit in controlling diarrhea in acute illness because of such factors as stress or medication. Fiber does play a role in maintaining gut integrity in all patients, whether they have diarrhea or not. Fiber may be recommended as part of a standard tube-feeding regimen to help assure gut mucosal integrity but not specifically to treat constipation/diarrhea. Further studies are necessary before the role of fiber in the management of constipation/diarrhea in tube-fed patients is determined.  相似文献   
8.
9.
Teeth with white spot lesions (WSL) might be more prone to enamel loss during bracket debonding. This in vitro study compared enamel loss from teeth with (n = 14) and without (n = 14) WSL after polishing with low-speed finishing burs or disks (Sof-Lex, 3M ESPE, St Paul, Minn). Debonded surfaces were analyzed with a contact stylus profilometer, and digitized data were compared with baseline readings by using AnSur NT software (Regents, University of Minnesota, Minneapolis, Minn). Specimen surfaces were also examined with a scanning electron microscope. Two-way analysis of variance was performed to analyze the data. In teeth without WSL, the volume losses were 0.16 mm(3) for the bur group and 0.10 mm(3) for the disk group; the mean maximum depths were 47.7 microm for the bur group and 54.3 microm for the disk group. In teeth with WSL, the volume losses were 0.06 and 0.17 mm(3), and the mean maximum depths were 35.1 and 48.7 microm for the bur and disk groups, respectively. There were no significant differences in enamel loss between the 2 groups of teeth without WSL (P =.12). However, in teeth with WSL, the burs removed less enamel than the disks (P = 0.006). Scanning electron microscope examination showed that any damage on the enamel surface was usually located in the cervical third of the teeth. On most specimens, even though tooth surfaces appeared resin-free to the naked eye, there were remnants of it. The differences between groups were so small that they might be clinically insignificant.  相似文献   
10.
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