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   1052461篇
  免费   69630篇
  国内免费   2629篇
耳鼻咽喉   15318篇
儿科学   34373篇
妇产科学   30071篇
基础医学   148575篇
口腔科学   29193篇
临床医学   86360篇
内科学   210397篇
皮肤病学   23171篇
神经病学   85752篇
特种医学   44375篇
外国民族医学   358篇
外科学   167205篇
综合类   20031篇
一般理论   286篇
预防医学   71877篇
眼科学   24430篇
药学   74614篇
中国医学   2131篇
肿瘤学   56203篇
  2018年   11770篇
  2017年   9357篇
  2016年   10704篇
  2015年   12107篇
  2014年   15950篇
  2013年   24227篇
  2012年   33435篇
  2011年   34587篇
  2010年   20831篇
  2009年   19220篇
  2008年   33355篇
  2007年   35672篇
  2006年   35853篇
  2005年   35817篇
  2004年   34162篇
  2003年   33264篇
  2002年   32751篇
  2001年   46428篇
  2000年   47756篇
  1999年   40757篇
  1998年   11337篇
  1997年   10289篇
  1996年   9943篇
  1995年   9135篇
  1994年   8746篇
  1993年   8199篇
  1992年   30244篇
  1991年   28957篇
  1990年   28354篇
  1989年   27157篇
  1988年   25141篇
  1987年   24787篇
  1986年   23685篇
  1985年   22575篇
  1984年   16873篇
  1983年   14362篇
  1982年   8710篇
  1979年   15823篇
  1978年   11096篇
  1977年   9387篇
  1976年   8780篇
  1975年   9895篇
  1974年   11656篇
  1973年   11067篇
  1972年   10569篇
  1971年   9795篇
  1970年   9396篇
  1969年   8766篇
  1968年   8387篇
  1967年   7747篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
OBJECTIVE: Hypertension is an important problem of the public health. Insufficient education of the people along with insufficient physical examination also plays a role in the poor success of the diagnosis and treatment of the hypertension. We investigated whether the skinfold thickness has an importance in the prediction of blood pressure or not. METHODS: In Aydin City area 110 women and 100 men selected by randomized sampling method were included into our study. Body mass index, blood pressure and skinfold thickness were measured according to the international guidelines. RESULTS: There was a moderate correlation between the skinfold and body mass index (r= 0.494, p=0.000) and there was a mild correlation between the body mass index and systolic and diastolic blood pressures (r=0.225, p=0.000 and r=0.300, p=0.000, respectively). There was no correlation between the skinfold thickness and systolic and diastolic blood pressures (r=0.058, p=0.400 and r=0.090, p=0.194, respectively). CONCLUSION: It is concluded that body mass index, not skinfold thickness, can be used for the prediction of the blood pressure. Some other factors independent from the body mass index might be the determinants of the skinfold thickness.  相似文献   
992.
993.
Intracellular recordings were made from cells in the hypothalamic supraoptic nucleus in the urethane-anaesthetized male rat using the ventral surgical approach. Impalements lasted from 5 min to 1 h and recorded cells had an input resistance of 55 to 170 megohms. Spikes of over 50 mV were recorded from 14 cells which could be antidromically activated by stimulation of the neural stalk. The spikes showed a hyperpolarizing afterpotential and the broadening characteristic of rapidly firing magnocellular neurons, which recovered rapidly (<200 ms). When depolarized, the cells showed evidence of a transient potassium current. Recurrent synaptic coupling between the recorded cell and adjacent cells would be expected to alter the hyperpolarizing afterpotential of an antidromic spike as compared with a spontaneous spike; no perceptible difference in the waveforms of the different types of spike could be detected in 11 spontaneously active cells. Application of just subthreshold stimuli to the neural stalk did not evoke depolarizing or hyperpolarizing potentials. Suprathreshold shocks to the neural stalk, when the antidromic spike was prevented by collision, also had no discernible effect on membrane potential. Thus intracellular recordings from magnocellular neurons in vivo revealed electrophysiological properties similar to those seen in vitro. No evidence for synaptic interconnection between magnocellular neurons was found in male rats.  相似文献   
994.
International Journal of Clinical Pharmacy - In order to calculate the minimum sterilization process conditions to obtain the generally accepted sterility level (less than 1·10?6...  相似文献   
995.
The concentration of human serum superoxide dismutase-1 (hSOD-1) containing copper and zinc ions were measured by radioimmunoassay healthy nonpregnant women, 15 normal pregnant women, 15 patients with mild to moderate hypertension (MMHSP) and 15 with severe hypertensive syndrome of pregnancy (SHSP). The mean serum hSOD-1 concentration in nonpregnant women was 148.84 +/- 60.53 (x +/- s) micrograms/L; while in the other 3 groups it was 394.19 +/- 122.21 micrograms/L, 377.12 +/- 173.45 micrograms/L and 581.15 +/- 118.50 micrograms/L. The results suggest that harmful free radicals increase gradually and a strong body defence system against oxidation damage of tissue cells is produced in the course of normal pregnancy and MMHSP. With cardionatrin treatment serum hSOD-1 concentrations of patients ameliorated returned to the level of normal pregnancy. The results indicate that there is a positive correlation between cardionatrin and hSOD-1 levels (r = 0.569, P less than 0.05), and a physiological regulation of the defence system exists, which may be related to the white blood cells. Hence, hSOD-1 probably plays a significant role in defence during normal pregnancy and hypertensive syndrome of pregnancy (HSP).
  相似文献   
996.
Programmed atrial stimulation at five atrial sites was performed to evaluate electrophysiologic atrial properties in 17 control patients (14 M, 3F, mean age 61 +/- 9 years) (Group A) and in 18 patients with paroxysmal atrial fibrillation (13 M, 5 F, mean age 61 +/- 5 years) (Group B) with normal sinus node function. The mean value of the P wave duration was similar in both groups. Programmed atrial stimulation was performed at five atrial sites: high, medium and low lateral wall, and high and low medial wall. We evaluated the following parameters: A) local conduction delay measured at the functional refractory period as the difference between A1-A2 and S1-S2 intervals; B) widening of local electrogram measured at the functional refractory period as the difference between A1-A2 interval measured at the end of each local electrogram and A1-A2 interval measured at the beginning of each local electrogram. We evaluated the mean and the maximum value of the two above-mentioned parameters; C) dispersion of effective refractory period and functional refractory period, determined as the longest minus the shortest refractory period from the range of refractory periods measured in each patient; D) the mean of effective refractory periods and functional refractory periods observed at five atrial sites. Mean and maximum local conduction delay, mean effective and functional refractory periods did not present significant differences in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
997.
N-Hydroxythalidomide (1d), a potential metabolite of thalidomide (1a), was synthesized from N-phthalyglutaminic acid anhydride (1b) and O-tetrahydropyraline hydroxylamine, followed by deprotection. The teratogenicity of 1d was studied using the Hen's-Egg-Test model which had been found applicable for 1a. 1d was more teratogenic to chicken embryos compared to 1a. The percentage of teratogenic malformations in the 1d groups was 28-46%, whereas the percentage in the 1a groups was 20-23%. The oxygen protected precursor N-hydroxythalidomide (1c) was less teratogenic (11-15%).  相似文献   
998.
999.
1000.
The development of the artificial pancreas represents an important step forward in modern diabetology. The practical and theoretical findings obtained by its application to Type 1 (insulin-dependent) diabetic patients has given new insights into modes of insulin secretion, pathophysiology of diabetes mellitus, and new forms of treatment, i.e. the development of portable insulin pumps and intensified conventional insulin therapy. All of these therapies provided better results than conventional insulin administration. However, there is no doubt that the restoration of normoglycaemia in a real sense is obtainable only by an implantable artificial pancreas or pancreas transplantation. The development of the implantable artificial pancreas, on the other hand, is dependent upon the development of a reliably working permanently implantable glucose sensor. The first attempts in that direction have opened new vistas as to the differences between blood and interstitial tissue glucose measurements, displaying different modes of regulation under normal and pathologic conditions. A number of barriers have to be overcome until the final goal has been attained: to obtain, by automated blood glucose control, narrow glycaemic fluctuations of the normal subject, and to prevent, hopefully, relentless diabetic complications.  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