全文获取类型
收费全文 | 2026283篇 |
免费 | 154471篇 |
国内免费 | 3001篇 |
专业分类
耳鼻咽喉 | 27254篇 |
儿科学 | 66617篇 |
妇产科学 | 55996篇 |
基础医学 | 303826篇 |
口腔科学 | 57393篇 |
临床医学 | 181769篇 |
内科学 | 388016篇 |
皮肤病学 | 43536篇 |
神经病学 | 156705篇 |
特种医学 | 80393篇 |
外国民族医学 | 523篇 |
外科学 | 306613篇 |
综合类 | 45791篇 |
现状与发展 | 4篇 |
一般理论 | 645篇 |
预防医学 | 155406篇 |
眼科学 | 46302篇 |
药学 | 154626篇 |
4篇 | |
中国医学 | 3756篇 |
肿瘤学 | 108580篇 |
出版年
2018年 | 19341篇 |
2016年 | 16800篇 |
2015年 | 19205篇 |
2014年 | 26386篇 |
2013年 | 39852篇 |
2012年 | 55047篇 |
2011年 | 58934篇 |
2010年 | 34518篇 |
2009年 | 32380篇 |
2008年 | 55702篇 |
2007年 | 59498篇 |
2006年 | 59871篇 |
2005年 | 57970篇 |
2004年 | 57069篇 |
2003年 | 54811篇 |
2002年 | 53529篇 |
2001年 | 91914篇 |
2000年 | 94810篇 |
1999年 | 80128篇 |
1998年 | 21939篇 |
1997年 | 19736篇 |
1996年 | 19713篇 |
1995年 | 19155篇 |
1994年 | 17955篇 |
1993年 | 17038篇 |
1992年 | 66157篇 |
1991年 | 65983篇 |
1990年 | 64966篇 |
1989年 | 63021篇 |
1988年 | 58541篇 |
1987年 | 57803篇 |
1986年 | 54663篇 |
1985年 | 52901篇 |
1984年 | 39493篇 |
1983年 | 33993篇 |
1982年 | 19538篇 |
1981年 | 17578篇 |
1979年 | 37692篇 |
1978年 | 26344篇 |
1977年 | 21996篇 |
1976年 | 21311篇 |
1975年 | 23174篇 |
1974年 | 27799篇 |
1973年 | 26735篇 |
1972年 | 24548篇 |
1971年 | 23186篇 |
1970年 | 21385篇 |
1969年 | 19994篇 |
1968年 | 18454篇 |
1967年 | 16652篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
931.
Maternal factors influencing development of embryos from mice superovulated with gonadotropins 总被引:5,自引:0,他引:5
In NMRI mice superovulation with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) increased mating rate, number of implantation sites, rate of advanced and delayed resorptions, as well as retarded sternebral ossification and cleft palate. On day 3 of gestation in preimplantation embryos, cell number and mitotic index were lower after superovulation than after spontaneous ovulation. However, when preimplantation embryos from superovulated and control females were transferred on day 3 of pregnancy to pseudopregnant recipients (10 embryos per female) no differences could be detected between the two groups of fetuses at term. The results of the embryo transfer experiments indicate that abnormal embryonic development after superovulation with gonadotropins is predominantly induced by effects of the hormone treatment on the maternal uterine environment. 相似文献
932.
J R Keane 《Archives of neurology》1989,46(7):761-762
A review of 96 consecutive patients who suffered neuro-ophthalmologic injuries in motorcycle accidents revealed a wide range of findings. These findings were similar to signs associated with other forms of closed-head trauma, aside from a higher incidence of trochlear nerve palsies. 相似文献
933.
B A Sommerville C G Scanes R Swaminathan A D Care S Harvey A Chadwick 《General and comparative endocrinology》1989,76(2):261-266
An experiment was carried out to investigate the effect of a range of estradiol (E2) doses (0.1-6.5 micrograms/g body wt/day) on vitamin D metabolism and the plasma levels of growth hormone (GH) and prolactin (PRL) in the growing chick. Doses of 0.5-0.7 microgram/g E2, which are insufficient to raise the plasma calcium level, did induce an increase in growth rate, an increase in 25-hydroxyvitamin D 1 alpha-hydroxylase (1-hydroxylase) and 24-hydroxylase activities, and an increase in plasma GH level. These parameters leveled off or fell over the dose range 1-2 micrograms/g E2 but there was evidence of a second peak in 1-hydroxylase activity at 6 micrograms/g E2. At this high dose rate, the plasma Ca level rose to 8 mM, as it does in the laying hen; 24-hydroxylase activity, growth rate, and plasma GH and plasma PRL levels all decreased. It was concluded that the dose response to estrogen in the growing chick is not linear and, in the case of 1-hydroxylase activity, may even be biphasic. 相似文献
934.
R J Smith 《The British journal of ophthalmology》1989,73(7):481-482
935.
936.
Addison's disease is rarely caused by metastatic cancer. We report a unique case of hypoadrenalism owing to metastatic transitional cell carcinoma of the bladder. The relevant literature is reviewed. 相似文献
937.
938.
In a previous study, we described a new method [3] to measure Na reabsorption by each segment of the human nephron independently. Reabsorption was expressed as equivalent volumes of solute-free water (CH2O) generated by the loop of Henle (CH2O-HL) and by the distal tubule (CH2O-DT), and dissipated by back diffusion (BD) across collecting ducts (CH2O-BD). These data were obtained during maximal water diuresis (MWD). The present study was undertaken to calculate CH2O-HL by experiments performed during maximal antidiuresis (MA). For this purpose, a new theoretical approach was devised, described by algebraic equations which allowed calculations of segmental transport during MA alone, where only CH2O-HL could be calculated independently. The study was performed on 14 normal volunteers who were studied twice by clearance measurements, firstly during MWD and again during MA. In each experiment, clearance periods were performed during baseline conditions and during the administration of furosemide (0.7 mg/kg bolus injection followed by 0.06 mg/kg/min maintenance infusion). From the values measured during either condition, segmental reabsorption was calculated. During MWD, CH2O-HL averaged 19.4 + 10.4, during MA 20.4 + 8.0 ml/min/GFR X 100; p greater than 0.05. The paired measurements were significantly correlated (r = 0.80; p less than 0.01). These data demonstrate that CH2O-HL obtained with the original theory is a reproducible result that can be confirmed with independent measurements obtained during different experimental conditions. Thus, measurements of segmental Na transport in the human nephron are feasible and can contribute important informations on disease states. 相似文献
939.
Endogenous opioids are present in neurons of the vagus and the intrinsic nervous system and they are colocalized with gastrin in antral G-cells. This raises the possibility that endogenous opioids modulate gastrin release. Stimulation of both cervical vagi (10V, 5Hz, 5ms) elicited an increase of arterial plasma gastrin levels at intragastric pH7 or pH2. The response at pH2 was 30% of that at luminal pH7. Atropine reduced vagally stimulated gastrin levels substantially. At luminal pH2 the small residual noncholinergic response was mediated neither by adrenergic mechanisms nor by endogenous opioids. At luminal pH 7 adrenergic blockade with phentolamine and propranolol reduced vagally stimulated gastrin by 60%. In the presence of atropine adrenergic blockade elicited only a small inhibitory effect suggesting that vagal activation of adrenergic mechanisms depends on atropine-sensitive cholinergic pathways. Blockade of opiate receptors by naloxone had no effect on vagal gastrin release, however, the noncholinergic gastrin response was reduced significantly by naloxone, suggesting that cholinergic mechanisms normally restrain activation of endogenous opioids during vagal stimulation. Naloxone had no effect on the noncholinergic, nonadrenergic stimulation of gastrin levels. These data suggest that endogenous opioids can contribute to vagal gastrin release provided the cholinergic restraint is blocked and adrenergic mechanisms stimulate endogenous opioids. In conclusion a major role of endogenous opioids in the regulation of vagal gastrin release can not be detected. 相似文献
940.
Neuroblastoma: the role of MR imaging 总被引:1,自引:0,他引:1
R B Dietrich H Kangarloo C Lenarsky S A Feig 《AJR. American journal of roentgenology》1987,148(5):937-942
Thirty-five MR examinations were performed in 17 children with neuroblastoma during the course of their diagnostic evaluation and treatment. Findings were confirmed by correlation with the results of other imaging techniques, biopsies, and surgical and autopsy findings. MR accurately detected the lesions and their extent in all patients. It correctly evaluated the possibility of resectability and showed metastases, response to treatment and development of complications. MR appears to be a reliable technique for the diagnosis, staging, and follow-up of children with neuroblastoma. 相似文献