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   3148668篇
  免费   222505篇
  国内免费   8485篇
耳鼻咽喉   43122篇
儿科学   100115篇
妇产科学   85927篇
基础医学   442636篇
口腔科学   88449篇
临床医学   285932篇
内科学   618134篇
皮肤病学   74027篇
神经病学   256536篇
特种医学   121435篇
外国民族医学   800篇
外科学   477128篇
综合类   63125篇
现状与发展   6篇
一般理论   1148篇
预防医学   236024篇
眼科学   71229篇
药学   232396篇
  10篇
中国医学   6677篇
肿瘤学   174802篇
  2019年   24245篇
  2018年   34531篇
  2017年   26575篇
  2016年   30754篇
  2015年   34679篇
  2014年   47657篇
  2013年   71034篇
  2012年   94560篇
  2011年   99847篇
  2010年   60089篇
  2009年   57627篇
  2008年   93879篇
  2007年   99433篇
  2006年   101316篇
  2005年   97244篇
  2004年   93648篇
  2003年   90125篇
  2002年   87340篇
  2001年   155796篇
  2000年   159755篇
  1999年   134793篇
  1998年   37618篇
  1997年   33213篇
  1996年   33455篇
  1995年   32319篇
  1994年   29658篇
  1993年   27750篇
  1992年   104503篇
  1991年   100401篇
  1990年   97391篇
  1989年   94066篇
  1988年   86155篇
  1987年   84454篇
  1986年   79147篇
  1985年   75581篇
  1984年   55922篇
  1983年   47358篇
  1982年   27360篇
  1981年   24347篇
  1979年   49483篇
  1978年   34453篇
  1977年   29483篇
  1976年   26963篇
  1975年   28868篇
  1974年   34309篇
  1973年   32498篇
  1972年   30514篇
  1971年   28415篇
  1970年   26471篇
  1969年   25338篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
982.
In a four month period 228 patients were admitted to the Wakari assessment and rehabilitation unit in Dunedin, New Zealand. One hundred and seventy subjects came from the community, 35 were transferred from the local public hospital, and 23 were readmitted. Median lengths of stay were 13, 26 and 10 days respectively. Assessment of activities of daily living (ADL) dependency on admission and discharge showed a significant improvement in ability by discharge, which correlated closely with place to which subjects were discharged, and with survival. There was 5% inpatients death rate which cumulated to 18%, 23%, 34%, 39% and 46% by six weeks, three months, six months, nine months and one year respectively. High discharge dependency was closely related to poor survival after discharge. Use of domiciliary services did not change because the savings from those who moved into institutions were cancelled out by those who were discharged back to the community being in need of increased social support.  相似文献   
983.
The resolution of three 2-substituted derivatives of idazoxan is described. The enantiomers show large separations in activity in a variety of in vitro and in vivo tests, and the active isomers are all potent and selective antagonists at the alpha 2-adrenoreceptor. The significance of these results in relation to those published on the enantiomers of idazoxan and to those on optically active alpha 2-adrenoreceptor agonists is discussed.  相似文献   
984.
Synthesis of Estradiol Haptens Two estradiol haptens, 4-(3β,17β-dihydroxyestran-7α-yl)butanoic acid ( 9 ) and 7α-(4-aminobutyl)-3β,17β-estradiols ( 13 ), were prepared from 19-nortestosterone by partial synthesis. The binding activity for the cytosol estrogen receptor was determined by competition against [3H]-estradiol; at a concentration of 2×10?7mol/l, compound 9 displaces 50% of [3H]-estradiol. Attached to AH-Sepharose 4B compound 9 allows the cytosol estrogen receptor from calf uterus to be concentrated 1800-fold by affinity chromatography.  相似文献   
985.
986.
987.
988.
The possible reversal by calcium of the inhibitory action of verapamil on the atrioventricular (AV) node was investigated in anesthetized, atropinized dogs, with cardiac pacing. The His bundle potentials were recorded by endocavitory electrode and the AV node effective refractory period measured by the extrastimulus method. Calcium infusion was effective against the impairment of AV nodal conduction induced by verapamil, provided it remained moderate: the gradual rise in the plasma calcium concentration counteracted the effects of an infusion of verapamil on conduction time and effective refractory period in the AV node, as long as it did not exceed 5 mmol/L. However, beyond this level, calcium appeared less and less capable of reversing the effects of verapamil. Thus, the protective action of calcium had a bell-shaped dose-response curve, with the optimum at 5 mmol/L. This biphasic influence is consistent with the opposite opinions previously given concerning the antagonism between calcium and calcium blockers, depending on whether hypercalcemia brought into play was mild or major. In any case, the prominent role played by calcium in the slow inward current in the AV node accounts for the antagonism, observed in vivo, between calcium and verapamil. The pacemaker activity of the sinoatrial (SA) node was less influenced by both calcium blocker and calcium.  相似文献   
989.
Haemophilus influenzae vaccine containing polyribosyl ribitol phosphate (PRP) or PRP covalently linked to diphtheria toxoid (PRP-D) was given to 94 healthy infants 17 to 22 months of age at the same time, but not at the same site, as a diphtheria-tetanus-pertussis booster. Systemic reactions were similar in the two vaccine groups and resembled those expected with the diphtheria-tetanus-pertussis injection alone. Six (13%) and seven (14%) of the PRP and PRP-D recipients, respectively, had minor local reactions to the Haemophilus vaccine. Among the 77 children who were not already naturally immune (ie, anti-PRP antibody concentration of less than or equal to 0.15 micrograms of protein per milliliter) before vaccination, PRP-D was significantly more effective than PRP in inducing protective levels of antibody. Only 15 (43%) of the 35 nonimmune PRP recipients achieved a concentration of greater than or equal to 0.15 microgram/mL and only seven (20%) reached a concentration greater than or equal to 1.0 micrograms/mL following vaccination. In contrast, 34 (81%) of the 42 nonimmune recipients of PRP-D had a concentration of greater than or equal to 0.15 microgram/mL following vaccine and 32 (62%) had a concentration of greater than or equal to 1.0 micrograms/mL (P less than or equal to .001). These results suggest that more than one-half of nonimmune 18-month-old infants will not respond to PRP with protective levels of antibody. In light of the current data, recommendation for revaccination at 24 months of age for those immunized at any younger age is appropriate.  相似文献   
990.
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