全文获取类型
收费全文 | 2141174篇 |
免费 | 165598篇 |
国内免费 | 7371篇 |
专业分类
耳鼻咽喉 | 28185篇 |
儿科学 | 63997篇 |
妇产科学 | 56446篇 |
基础医学 | 296378篇 |
口腔科学 | 61386篇 |
临床医学 | 191609篇 |
内科学 | 430934篇 |
皮肤病学 | 48481篇 |
神经病学 | 172734篇 |
特种医学 | 86523篇 |
外国民族医学 | 346篇 |
外科学 | 340927篇 |
综合类 | 46814篇 |
现状与发展 | 3篇 |
一般理论 | 678篇 |
预防医学 | 161835篇 |
眼科学 | 46803篇 |
药学 | 157006篇 |
9篇 | |
中国医学 | 4089篇 |
肿瘤学 | 118960篇 |
出版年
2018年 | 21326篇 |
2017年 | 16803篇 |
2016年 | 19565篇 |
2015年 | 22057篇 |
2014年 | 30629篇 |
2013年 | 45554篇 |
2012年 | 58206篇 |
2011年 | 61878篇 |
2010年 | 37831篇 |
2009年 | 36622篇 |
2008年 | 58604篇 |
2007年 | 62316篇 |
2006年 | 63856篇 |
2005年 | 61758篇 |
2004年 | 59048篇 |
2003年 | 57343篇 |
2002年 | 55056篇 |
2001年 | 109579篇 |
2000年 | 113088篇 |
1999年 | 94560篇 |
1998年 | 26043篇 |
1997年 | 22962篇 |
1996年 | 23940篇 |
1995年 | 23524篇 |
1994年 | 21874篇 |
1993年 | 20363篇 |
1992年 | 75804篇 |
1991年 | 73295篇 |
1990年 | 70755篇 |
1989年 | 68082篇 |
1988年 | 62795篇 |
1987年 | 61363篇 |
1986年 | 57718篇 |
1985年 | 55642篇 |
1984年 | 41279篇 |
1983年 | 34911篇 |
1982年 | 20376篇 |
1981年 | 18068篇 |
1980年 | 16930篇 |
1979年 | 36917篇 |
1978年 | 26010篇 |
1977年 | 22093篇 |
1976年 | 19888篇 |
1975年 | 21157篇 |
1974年 | 25138篇 |
1973年 | 23930篇 |
1972年 | 22417篇 |
1971年 | 20860篇 |
1970年 | 19345篇 |
1969年 | 18139篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
971.
972.
Apart from cannabis abuse in northern and southern Africa and khat chewing in north-eastern Africa, the history of drug abuse in Africa is relatively short. The abuse of drugs in Africa is nevertheless escalating rapidly from cannabis abuse to the more dangerous drugs and from limited groups of drug users to a wider range of people abusing drugs. The most common and available drug of abuse is still cannabis, which is known to be a contributing factor to the occurrence of a schizophrenic-like psychosis. The trafficking in and abuse of cocaine and heroin are the most recent developments in some African countries that had had no previous experience with these drugs. Efforts should be made to design and implement drug abuse assessment programmes to determine the real magnitude and characteristics of the problem and to monitor its trends. A lack of funds and a shortage of adequately trained personnel have made it difficult to implement drug abuse control programmes. In addition to formal drug control involving the implementation of legislation, there is an informal system of drug abuse control operating through the family, church, school, neighbourhood and work environment, as well as healthy recreational activities. It is suggested that efforts in African countries should be directed towards strengthening not only the formal drug control system but also informal control in order to compensate for the insufficient funds and the shortage of personnel trained in implementing formal drug control measures. It is very likely that the drug problems in African countries will worsen in future unless more effective measures are implemented to arrest the current situation. 相似文献
973.
974.
975.
976.
A López Bernal D J Hansell S Alexander A C Turnbull 《British journal of obstetrics and gynaecology》1987,94(11):1052-1058
The production of progesterone from pregnenolone, of cortisol from cortisone and of prostaglandin E (PGE) under basal and arachidonic acid-stimulated conditions was measured in cells dispersed from chorion and decidua. The cells were obtained after delivery from four groups of women: following spontaneous labour at term (38-42 weeks gestation), at elective caesarean section at term before the onset of labour, after induced labour at term, and after uncomplicated preterm (27-36 weeks) labour. Chorionic cells had a high progesterone output with relatively low cortisol and PGE production, whereas decidual cells had a high cortisol and PGE production rate. Free arachidonic acid stimulated PGE production in both decidual and chorionic cells. There were no significant differences in either steroid or PGE production among the four groups studied. These data suggest that steroid dehydrogenase activity in choriodecidual cells is not related to the mode of onset of labour and that the increased prostaglandin production in intrauterine tissues associated with parturition is due to enhanced availability of arachidonic acid. 相似文献
977.
A brief historical review of the role of female medical students and female physicians in American medicine is presented. The 1985-1986 Council on Resident Education in Obstetrics and Gynecology Residency Data Bank was analyzed for gender distribution. Questionnaire studies were undertaken to study the possible effect of the increasing number of female residents in an obstetrics and gynecology residency program. Queries were sent to current and former residents, the attending staff, and the nursing and anesthesiology staffs. In order to evaluate the national scene, letters were mailed to directors of programs with 20 or more residents. The overall results indicated female residents have a positive effect on residency training. 相似文献
978.
Y. O. Karatasso I. V. Logunova M. G. Sergeeva E. N. Nikolaev S. D. Varfolomeev V. V. Chistyakov 《Pharmaceutical Chemistry Journal》2007,41(3):166-169
A highly sensitive method for the quantitative determination of a potential antiarrhythmic drug (OF-7976) in the blood plasma
has been developed. The method is based on the electron spray ionization/mass spectrometry (ESI-MS) technique without preliminary
chromatographic separation and makes use of nibentan as the internal standard. A linear relationship between drug concentration
and the peak intensity of ions of the analyzed substance (m/z = 398) and the internal standard (m/z = 382) is established. The detection limit is 3 ng/(0.5 ml plasma). The method is linear from 3 to 25 ng/(0.5 ml plasma)
with a correlation coefficient of 0.98. The coefficient of variation was less than 7 %.
__________
Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 41, No. 3, pp. 45–48, March, 2007. 相似文献
979.
Birgit T Priest Kenneth M Blumenthal Jaime J Smith Vivien A Warren McHardy M Smith 《Toxicon》2007,49(2):194-201
The tarantula venom peptides ProTx-I and ProTx-II inhibit voltage-gated sodium channels by shifting their voltage dependence of activation to a more positive potential, thus acting by a mechanism similar to that of potassium channel gating modifiers such as hanatoxin and VSTX1. ProTx-I and ProTx-II inhibit all sodium channel (Nav1) subtypes tested with similar potency and represent the first potent peptidyl inhibitors of TTX-resistant sodium channels. Like gating modifiers of potassium channels, ProTx-I and ProTx-II conform to the inhibitory cystine knot motif, and ProTx-II was demonstrated to bind to sodium channels in the closed state. Both toxins have been synthesized chemically, and ProTx-II, produced by recombinant means, has been used to map the interaction surface of the peptide with the Nav1.5 channel. In comparison, beta-scorpion toxins activate sodium channels by shifting the voltage dependence of activation to more negative potentials, and together these peptides represent valuable tools for exploring the gating mechanism of sodium channels. 相似文献
980.