全文获取类型
收费全文 | 6554篇 |
免费 | 364篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 131篇 |
儿科学 | 391篇 |
妇产科学 | 163篇 |
基础医学 | 682篇 |
口腔科学 | 112篇 |
临床医学 | 376篇 |
内科学 | 1281篇 |
皮肤病学 | 127篇 |
神经病学 | 432篇 |
特种医学 | 188篇 |
外科学 | 973篇 |
综合类 | 288篇 |
一般理论 | 1篇 |
预防医学 | 383篇 |
眼科学 | 296篇 |
药学 | 496篇 |
中国医学 | 19篇 |
肿瘤学 | 586篇 |
出版年
2022年 | 88篇 |
2021年 | 154篇 |
2020年 | 90篇 |
2019年 | 131篇 |
2018年 | 151篇 |
2017年 | 107篇 |
2016年 | 158篇 |
2015年 | 142篇 |
2014年 | 223篇 |
2013年 | 299篇 |
2012年 | 402篇 |
2011年 | 475篇 |
2010年 | 265篇 |
2009年 | 244篇 |
2008年 | 344篇 |
2007年 | 389篇 |
2006年 | 381篇 |
2005年 | 315篇 |
2004年 | 317篇 |
2003年 | 270篇 |
2002年 | 213篇 |
2001年 | 140篇 |
2000年 | 157篇 |
1999年 | 146篇 |
1998年 | 51篇 |
1997年 | 49篇 |
1996年 | 51篇 |
1995年 | 36篇 |
1993年 | 28篇 |
1992年 | 62篇 |
1991年 | 52篇 |
1990年 | 49篇 |
1989年 | 54篇 |
1988年 | 45篇 |
1987年 | 61篇 |
1986年 | 52篇 |
1985年 | 58篇 |
1984年 | 55篇 |
1983年 | 38篇 |
1979年 | 27篇 |
1978年 | 30篇 |
1977年 | 30篇 |
1974年 | 37篇 |
1973年 | 49篇 |
1972年 | 42篇 |
1971年 | 37篇 |
1970年 | 30篇 |
1969年 | 35篇 |
1968年 | 36篇 |
1967年 | 25篇 |
排序方式: 共有6925条查询结果,搜索用时 15 毫秒
41.
42.
Cell-based bioassays have been suggested for screening of hormones and drug bioactivities. They are a plausible alternative
to animal based methods. The technique used is called receptor/reporter system. Receptor/reporter system was initially developed
as a research technique to understand gene function. Often reporter constructs containing viral promoters were used because
they could be expressed with very 'high' magnitude in a variety of cell types in the laboratory. On the other hand mammalian
genes are expressed in a cell/tissue specific manner, which makes them (i.e. cells/tissues) specialized for specific function in vivo. Therefore, if the receptor/reporter system is to be used as a cell-based screen for testing of hormones and drugs for human
therapy then the choice of cell line as well as the promoter in the reporter module is of prime importance so as to get a
realistic measure of the bioactivities of 'test' compounds. We evaluated two conventionally used viral promoters and a natural
mammalian promoter, regulated by steroid hormone progesterone, in a cell-based receptor/reporter system. The promoters were
spliced into vectors expressing enzyme CAT (chloramphenicol acetyl transferase), which served as a reporter of their magnitudes
and consistencies in controlling gene expressions. They were introduced into breast cell lines T47D and MCF-7, which served
as a cell-based source of progesterone receptors. The yardstick of their reliability was highest magnitude as well as consistency
in CAT expression on induction by sequential doses of progesterone. All the promoters responded to induction by progesterone
doses ranging from 10-12 to 10-6 molar by expressing CAT enzyme, albeit with varying magnitudes and consistencies. The natural mammalian promoter showed the
most coherence in magnitude as well as dose dependent expression profile in both the cell lines. Our study casts doubts on
use of viral promoters in a cell-based bioassay for measuring bioactivities of drugs and hormones for human therapy and suggests
caution regardingtranslation in toto, of a research technique as a cell-based bioassay for drug screening. 相似文献
43.
44.
Bhattacharya SK Singh NK Prasad RC Sinha PR 《The Journal of the Association of Physicians of India》1998,46(8):675-677
Thirty four patients aged 14 to 65 years (18 males and 16 females) admitted to the University Hospital with various unusual and severe forms of adverse drug reactions were studied. It comprised of toxic epidermal necrolysis in 8 patients, systemic vasculitis in 7 of which 3 patients had gangrene of fingers and/or toes, severe erosive gastritis in 9 patients, Stevens-Johnson syndrome in 7 patients, thrombocytopenic purpura in 2 patients and generalised convulsions in 1 patient. Various drugs responsible for causing these adverse drug reactions included antibacterials, antimalarials, anticonvulsants, antituberculars and nonsteroidal anti-inflammatory drugs. Most of the patients recovered. However, 5 of the 8 patients having toxic epidermal necrolysis died of which 2 patients had developed tetanus as a preterminal event. In view of ongoing addition of newer drugs to the therapeutic armamentarium and an increasing incidence of various unusual and severe forms of adverse drug reactions, it is our contention that a separate adverse drug reaction monitoring cell should be established in every hospital setting. 相似文献
45.
J. N. Sinha S. Gurtu D. K. Sharma K. P. Bhargava 《Naunyn-Schmiedeberg's archives of pharmacology》1985,330(3):163-168
Summary Microinjection of noradrenaline and clonidine into lateral medullary pressor area (LMPA) of chloralose anaesthetized cats produced dose dependent decrease in blood pressure without affecting heart rate, while phenylephrine did not elicit any cardiovascular response. Selective
2-adrenoceptor, antagonists idazoxan and piperoxan, microinjected locally, blocked the effects of the agonists but prazosin and phenoxybenzamine, which are relatively selective for
1-adrenoceptors, failed to do so. Clonidine did not elicit any response in guanethidine pretreated cats but noradrenaline microinjected into LMPA of these animals induced a pressor response which was blocked by prazosin pretreatment. It is concluded that catecholaminergic fibres impinging upon this are inhibit the activity of the inhibitory second order baroreceptor neurone by activating
1-adrenoceptors while
2-adrenoceptors situated presynaptically on these inhibitory catecholaminergic nerve terminals are responsible for the manifestation of the hypotensive effect of clonidine and exogenously administered noradrenaline. 相似文献
46.
J. N. Sinha D. K. Sharma S. Gurtu K. K. Pant K. P. Bhargava 《Naunyn-Schmiedeberg's archives of pharmacology》1984,326(3):193-197
Summary The Bezold-Jarisch reflex characterized by hypotension and bradycardia was elicited in anaesthetized artificially respired dogs (pretreated with a beta-adrenoceptor antagonist) using capsaicin 10 g/kg (i.v.). Intracisternal administration of the highly selective clonidine-like alpha2 adrenoceptor agonists B-HT 920 (10 g/kg) or B-HT 933 (30 g/kg) significantly facilitated this reflex bradycardia. The involvement of central alpha2-adrenoceptors is suggested as intracisternal administration of the alpha2 adrenoceptor blocking drugs yohimbine (50 g/kg) and piperoxan (50 g/kg) antagonized this facilitation. B-HT 920 also facilitated the vagally mediated baroreceptor reflex to the hypertensive effect of intravenous noradrenaline (3 g/kg). Although the Bezold-Jarisch reflex and the baroreceptor reflex have different afferent pathways, both reflexes may either converge into a common pathway or have separate neuronal chains within the medulla; however, this study indicates that both have a similar central modulatory system stimulated by alpha2 adrenoceptors. 相似文献
47.
48.
49.
Louise B. Russell Sun-Young Kim Cristiana Toscano Ben Cosgriff Ruth Minamisava Ana Lucia Andrade Colin Sanderson Anushua Sinha 《Vaccine》2021,39(1):158-166
BackgroundThis paper compares cost-effectiveness results from two models of maternal immunization to prevent pertussis in infants in Brazil, one static, one dynamic, to explore when static models are adequate for public health decisions and when the extra effort required by dynamic models is worthwhile.MethodsWe defined two scenarios to explore key differences between static and dynamic models, herd immunity and time horizon. Scenario 1 evaluates the incremental cost/DALY of maternal acellular pertussis (aP) immunization as routine infant vaccination coverage ranges from low/moderate up to, and above, the threshold at which herd immunity begins to eliminate pertussis. Scenario 2 compares cost-effectiveness estimates over the models’ different time horizons. Maternal vaccine prices of $9.55/dose (base case) and $1/dose were evaluated.ResultsThe dynamic model shows that maternal immunization could be cost-saving as well as life-saving at low levels of infant vaccination coverage. When infant coverage reaches the threshold range (90–95%), it is expensive: the dynamic model estimates that maternal immunization costs $2 million/DALY at infant coverage > 95% and maternal vaccine price of $9.55/dose; at $1/dose, cost/DALY is $200,000. By contrast, the static model estimates costs/DALY only modestly higher at high than at low infant coverage. When the models’ estimates over their different time horizons are compared at infant coverage < 90–95%, their projections fall in the same range.ConclusionsStatic models may serve to explore an intervention’s cost-effectiveness against infectious disease: the direction and principal drivers of change were the same in both models. When, however, an intervention too small to have significant herd immunity effects itself, such as maternal aP immunization, takes place against a background of vaccination in the rest of the population, a dynamic model is crucial to accurate estimates of cost-effectiveness. This finding is particularly important in the context of widely varying routine infant vaccination rates globally.Clinical Trial registryClinical Trial registry name and registration number: Not applicable. 相似文献