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   931969篇
  免费   66170篇
  国内免费   1342篇
耳鼻咽喉   12957篇
儿科学   24359篇
妇产科学   23234篇
基础医学   132895篇
口腔科学   28246篇
临床医学   80535篇
内科学   183252篇
皮肤病学   19226篇
神经病学   72170篇
特种医学   36798篇
外国民族医学   79篇
外科学   152070篇
综合类   18043篇
现状与发展   1篇
一般理论   234篇
预防医学   61747篇
眼科学   21307篇
药学   72530篇
  3篇
中国医学   2162篇
肿瘤学   57633篇
  2018年   8962篇
  2017年   7026篇
  2016年   7758篇
  2015年   8858篇
  2014年   11981篇
  2013年   17491篇
  2012年   24078篇
  2011年   25032篇
  2010年   14799篇
  2009年   14266篇
  2008年   24593篇
  2007年   25686篇
  2006年   26475篇
  2005年   25426篇
  2004年   24559篇
  2003年   23598篇
  2002年   23144篇
  2001年   54726篇
  2000年   56546篇
  1999年   46949篇
  1998年   10731篇
  1997年   9467篇
  1996年   9594篇
  1995年   8927篇
  1994年   8279篇
  1993年   7594篇
  1992年   35487篇
  1991年   33913篇
  1990年   32736篇
  1989年   31869篇
  1988年   28992篇
  1987年   28252篇
  1986年   26289篇
  1985年   25146篇
  1984年   17832篇
  1983年   15142篇
  1982年   7796篇
  1981年   6771篇
  1979年   15783篇
  1978年   10598篇
  1977年   9052篇
  1976年   7872篇
  1975年   8631篇
  1974年   10470篇
  1973年   9858篇
  1972年   9357篇
  1971年   8853篇
  1970年   8426篇
  1969年   7923篇
  1968年   7200篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Background: The authors compared the efficacy of the different approaches to saphenous nerve block.

Methods: The following approaches to saphenous nerve block were compared in 10 volunteers: perifemoral, transsartorial, block at the medial femoral condyle, below-the-knee field block, and blockade at the level of the medial malleolus. Each volunteer underwent all five blocks, and the interval between blocks was 3-7 days. The sequence of injection was randomized by Latin square design. Sensory blockade at the medial aspects of the leg and foot and the strength of the anterior thigh muscles were noted.

Results: The transsartorial, perifemoral, and below-the-knee field block approaches were more effective than block at the medial femoral condyle in providing sensory anesthesia to the medial aspect of the leg. The transsartorial approach was more effective than block at the medial femoral condyle and below-the-knee field block in providing sensory anesthesia to the medial aspect of the foot. Compared with the perifemoral approach, the transsartorial approach did not cause weakness of the hip flexors and the knee extensors. In volunteers with partial numbness in the medial aspect of the foot, supplemental block of the medial dorsal cutaneous branch of the superficial peroneal nerve resulted in complete sensory blockade.  相似文献   

992.
The loss of available iodine from povidone-iodine solution stored in contact with two different polyetherpolyurethane foams was monitored as a function of time and temperature. Statistical evaluation of the results for the four temperatures studied [ambient (25 degrees), 30, 45 and 55 degrees C] indicated the chemical equivalence of the two foams as storage and delivery systems for povidone-iodine solution in terms of solution stability. In addition, application of a first-order kinetic model to the data produced an acceptable fit. An Arrhenius-type evaluation of the resulting rate constants yielded a linear relationship which was shown to be useful for predicting loss of available iodine under ambient temperature conditions of storage.  相似文献   
993.
Heated sugar/amino acid reaction mixtures, known to contain products that are clastogenic and/or mutagenic to cells in vitro, were evaluated for clastogenic activity in mouse bone marrow using the erythrocyte micronucleus assay. Heated (i.e. browned) fructose/lysine reaction mixtures were also evaluated in the Salmonella his-reversion assay and the Chinese hamster ovary (CHO) cell chromosomal aberration assay to confirm and extend previous in vitro observations. Significant mutagenicity of fructose/lysine mixtures was observed in Salmonella typhimurium strains TA100, TA2637, TA98 and TA102, with greater activity in mixtures heated at pH 10 than at pH 7. S-9 decreased the activity in strains TA100, TA2637 and TA98, but increased the activity in strain TA102. Both pH 7 and pH 10 reaction mixtures of the fructose/lysine browning reaction were highly clastogenic in CHO cells. Heated mixtures of fructose and lysine, and of glucose or ribose with lysine, histidine, tryptophan or cysteine, did not increase the frequency of micronucleated erythrocytes in mice when administered by the oral route. This indicates the absence of chromosomal aberrations in erythrocyte precursor cells, and indicates that the genotoxic components of the browned mixtures are not absorbed and distributed to bone marrow cells in amounts sufficient to induce micronuclei when given orally. Because sugar/amino acid browning reactions occur commonly in heated foods, it is important to evaluate further the in vivo genotoxicity of browning products in cell populations other than bone marrow.  相似文献   
994.
Thiopentone, propofol and etomidate inhibit the contractions of the rat isolated atria and portal vein. The actions of thiopentone and propofol summate with those of verapamil and nifedipine. Verapamil potentiates the action of etomidate on both preparations. The depressant actions of thiopentone and propofol on the portal vein are associated with a reduced response to calcium. Etomidate does not reduce the response to calcium in this preparation.  相似文献   
995.
996.
997.
Five years after treatment in a controlled trial, in which all had received self-exposure homework, a group of 40 agoraphobic outpatients retained marked improvement in agoraphobia, mood, and free-floating anxiety. Frequency of spontaneous panics decreased as much in those who had placebo and self-exposure as in those who received imipramine and self-exposure. Few patients, however, were completely well at 5 years and over half had received further treatment for agoraphobia during the follow-up. Patients who were still highly phobic at the end of the clinical trial were more often prescribed psychotropic medication during follow-up and remained phobic at 5 years. Phobic improvement had generalized more in those patients with very low than in those with moderate pretreatment Hamilton depression scores. Frequency of initial spontaneous panics did not predict outcome. Improvement in agoraphobia was associated with improved marital adjustment. Those who began with the best marital, work, and social adjustment were more improved in their phobias 5 years later.  相似文献   
998.
999.
1000.
Psychiatric morbidity in Hobart's dependent aged   总被引:1,自引:0,他引:1  
Psychiatric morbidity in the dependent aged was studied in the elderly population of Hobart's nursing homes and long-stay hospitals. Only patients with home addresses in Hobart and who were admitted for the first time aged 70 years or over were included. Three hundred and twelve persons were interviewed with a standard interview, and an informant was interviewed when appropriate. The medical records were searched for diagnoses and drug treatments. Physical disability was rated on an ad hoc scale. Comparisons were made of the prevalence of dementia, depression and anxiety in different types of unit, and between these and two domiciliary samples, one of which received domiciliary nursing services (n = 100) and the other not (n = 100). The differential use of institutions by men and women, and a possible sex difference in the prevalence of dementia 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