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   3342篇
  免费   248篇
  国内免费   13篇
耳鼻咽喉   41篇
儿科学   106篇
妇产科学   90篇
基础医学   432篇
口腔科学   64篇
临床医学   290篇
内科学   795篇
皮肤病学   49篇
神经病学   221篇
特种医学   92篇
外科学   576篇
综合类   53篇
预防医学   261篇
眼科学   65篇
药学   230篇
中国医学   20篇
肿瘤学   218篇
  2023年   29篇
  2022年   74篇
  2021年   107篇
  2020年   74篇
  2019年   115篇
  2018年   124篇
  2017年   68篇
  2016年   74篇
  2015年   100篇
  2014年   132篇
  2013年   166篇
  2012年   234篇
  2011年   236篇
  2010年   147篇
  2009年   115篇
  2008年   177篇
  2007年   168篇
  2006年   155篇
  2005年   148篇
  2004年   152篇
  2003年   123篇
  2002年   111篇
  2001年   40篇
  2000年   52篇
  1999年   53篇
  1998年   26篇
  1997年   19篇
  1996年   27篇
  1995年   21篇
  1994年   20篇
  1993年   21篇
  1992年   38篇
  1991年   35篇
  1990年   33篇
  1989年   48篇
  1988年   44篇
  1987年   34篇
  1986年   32篇
  1985年   29篇
  1984年   23篇
  1983年   20篇
  1982年   8篇
  1981年   7篇
  1980年   15篇
  1979年   25篇
  1978年   22篇
  1977年   12篇
  1976年   7篇
  1974年   11篇
  1973年   11篇
排序方式: 共有3603条查询结果,搜索用时 15 毫秒
11.
Besides distal symmetrical sensory polyneuropathy (DSSP), middle-aged diabetic patients may present with focal or multifocal neuropathies, including proximal neuropathy of the lower limbs, the pathophysiological features of which are uncertain. We studied 10 non–insulin-dependent diabetic patients, 45 to 72 years of age, who developed a painful proximal neuropathy of the lower limbs for which other causes of neuropathy were carefully excluded. The proximal neuropathy was asymmetrical in all patients, sensory in 4, motor and sensory in the others. Signs of DSSP were present in all. A sample of the intermediate cutaneous nerve of the thigh, a sensory branch of the femoral nerve, was taken by biopsy and examined by light and electron microscopy. Examination of the nerve specimens revealed ischemic nerve lesions in 3 patients. Nerve ischemia was associated with vasculitis and inflammatory infiltration in 2 of them. In the other patients the lesions of the cutaneous nerve of the thigh included a varying incidence of axonal and demyelinative lesions similar to those observed in DSSP, with mild inflammatory infiltration in 4 of them. The density of myelinated and of unmyelinated was variably decreased. This study shows that axonal and demyelinative lesions similar to those found in diabetic DSSP are present in proximal nerves in mild forms of proximal diabetic neuropathy; while nerve ischemia, inflammatory infiltration, and vasculitis are encountered in the most severe forms of proximal diabetic neuropathy.  相似文献   
12.
13.
14.
OBJECTIVE: To compare the efficacy, safety, and duration of effect of four doses of botulinum toxin type A in the treatment of glabellar rhytids in females. DESIGN: Double-blind, randomized, parallel-group, dose-ranging trial followed by an open-label extension. SETTING: Private dermatologic clinic. SUBJECTS: Eighty female subjects with moderate to severe wrinkles at maximum frown entered the study. The first 40 subjects completing the double-blind phase entered the open-label extension. INTERVENTION: Random administration of 10, 20, 30, or 40 U botulinum toxin type A in divided doses. Open-label trial: 30 U botulinum toxin type A at the same sites in divided doses. MAIN OUTCOME MEASUREMENTS: Trained observer and subject assessments of wrinkle severity at maximum frown and repose using the Facial Wrinkle Scale (0 = none to 3 = severe), subject satisfaction, and adverse events. Follow-up monthly for up to 1 year postinjection. RESULTS: Relapse rates and responder rates revealed benefits lasting 3 to 6 months or longer. Objectively, 10 U of botulinum toxin type A was significantly less effective than 20, 30, or 40 U. The relapse rate at 4 months was significantly higher in the 10 U group (83%) versus 40, 30, or 20 U (28%, 30%, and 33%, respectively). Subject satisfaction was high in all groups. Duration of effect and response rates were sustained during the open-label extension. Adverse effects were mild and infrequent. CONCLUSION: Twenty to 40 U botulinum toxin type A doses were significantly more effective at reducing glabellar lines than 10 U. Most subjects experienced benefits for 3 to 4 months; some subjects demonstrated effect for up to 12 months.  相似文献   
15.
The overlooked, retained double J stent   总被引:2,自引:0,他引:2  
A series of 4 patients with long overlooked, retained ureteral stents is presented to illustrate the variable, unpredictable, and at times, hazardous course of such patients. These cases are cited to re-emphasize the need for careful documentation, observation, and follow-up of patients in whom stents are placed.  相似文献   
16.
Tyrosine phosphorylation status was investigated during mousemammary tumor development using non-tumorigenic and tumorigenichyperplastic outgrowth lines. These outgrowth lines were comparedwith normal mammary glands from pregnant mice and with theircorresponding tumors. The levels of total tyrosine phosphorylationin proteins of hyperplastic and neoplastic tissues were 4.7-and3.4-fold higher than in the normal gland respectively. Theseresults indicate that increases in tyrosine phosphorylationoccur in the earliest stages of neoplastic development and arenot restricted to neoplastic cells per se. These results ledto the identification of the specific proteins showing highlevels of tyrosine phosphorylation. Of the eight molecular weightbands of proteins exhibiting detectable levels of tyrosine phosphorylation,the only proteins exhibiting consistently different degreesof phosphorylation between hyperplasias and tumors were of  相似文献   
17.
Immunohistochemistry is a valuable adjunct to the identification of Hodgkin's disease (HD) Reed-Sternberg (RS) cells, and in the differential diagnosis between HD, non-Hodgkin's lymphomas, and nonlymphoid neoplasms containing RS-like cells. The characteristic phenotype of RS cells in different subtypes of HD is described, with an emphasis on routine immunohistochemical stains. Some of the conflicting literature on this subject is reviewed to highlight pitfalls and controversies in the field.  相似文献   
18.
19.
20.
Reaction of 6-(acetoxymethyl)-2,4-dichloropyrido[3,2-d]pyrimidine (I) with some nucleophiles was investigated. When I reacted with sodium azide afforded 2,4-diazido derivative (II). Treatment of II with sodium hydroxide underwent cyclization of the 2-azido group to tetrazolo, replacement of 4-azido group by hydroxide ion, and hydrolysis of 6-acetoxy moiety to hydroxy methyl derivative (III). While, reaction of I with hydrazine hydrate resulted in the formation of 2,4-dihydrozino-6-hydroxymethyl derivative (IV).  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