全文获取类型
收费全文 | 2995篇 |
免费 | 194篇 |
国内免费 | 50篇 |
专业分类
耳鼻咽喉 | 20篇 |
儿科学 | 110篇 |
妇产科学 | 64篇 |
基础医学 | 468篇 |
口腔科学 | 70篇 |
临床医学 | 224篇 |
内科学 | 654篇 |
皮肤病学 | 40篇 |
神经病学 | 176篇 |
特种医学 | 236篇 |
外科学 | 393篇 |
综合类 | 132篇 |
一般理论 | 1篇 |
预防医学 | 156篇 |
眼科学 | 50篇 |
药学 | 223篇 |
中国医学 | 13篇 |
肿瘤学 | 209篇 |
出版年
2024年 | 5篇 |
2023年 | 20篇 |
2022年 | 49篇 |
2021年 | 72篇 |
2020年 | 35篇 |
2019年 | 71篇 |
2018年 | 66篇 |
2017年 | 49篇 |
2016年 | 74篇 |
2015年 | 104篇 |
2014年 | 173篇 |
2013年 | 166篇 |
2012年 | 198篇 |
2011年 | 227篇 |
2010年 | 167篇 |
2009年 | 143篇 |
2008年 | 146篇 |
2007年 | 161篇 |
2006年 | 142篇 |
2005年 | 109篇 |
2004年 | 94篇 |
2003年 | 97篇 |
2002年 | 74篇 |
2001年 | 64篇 |
2000年 | 41篇 |
1999年 | 46篇 |
1998年 | 66篇 |
1997年 | 59篇 |
1996年 | 60篇 |
1995年 | 51篇 |
1994年 | 52篇 |
1993年 | 29篇 |
1992年 | 21篇 |
1991年 | 30篇 |
1990年 | 21篇 |
1989年 | 38篇 |
1988年 | 36篇 |
1987年 | 22篇 |
1986年 | 23篇 |
1985年 | 20篇 |
1984年 | 17篇 |
1983年 | 9篇 |
1982年 | 15篇 |
1981年 | 12篇 |
1980年 | 13篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1977年 | 11篇 |
1976年 | 6篇 |
1975年 | 5篇 |
排序方式: 共有3239条查询结果,搜索用时 31 毫秒
1.
2.
Paul Wan Sia Heng Tin Wui Wong Wai See Cheong 《European journal of pharmaceutical sciences》2003,19(5):381-393
The melt agglomeration process of lactose powder with hydrogenated cottonseed oil (HCO) as the hydrophobic meltable binder was investigated by studying the physicochemical properties of molten HCO modified by sucrose stearates S170, S770 and S1570. The size, size distribution, micromeritic and adhesion properties of agglomerates as well as surface tension, contact angle, viscosity and specific volume of molten HCO, with and without sucrose stearates, were examined. The viscosity, specific volume and surface tension of molten HCO were found to be modified to varying extents by sucrose stearates which are available in different HLB values and melt properties. The growth of melt agglomerates was promoted predominantly by an increase in viscosity, an increase in specific volume or a decrease in surface tension of the molten binding liquid. The agglomerate growth propensity was higher with an increase in inter-particulate binding strength, agglomerate surface wetness and extent of agglomerate consolidation which enhanced the liquid migration from agglomerate core to periphery leading to an increased surface plasticity for coalescence. The inclusion of high concentrations of completely meltable sucrose stearate S170 greatly induced the growth of agglomerates through increased specific volume and viscosity of the molten binding liquid. On the other hand, the inclusion of incompletely meltable sucrose stearates S770 and S1570 promoted the agglomeration mainly via the reduction in surface tension of the molten binding liquid with declining agglomerate growth propensity at high sucrose stearate concentrations. In addition to being an agglomeration modifier, sucrose stearate demonstrated anti-adherent property in melt agglomeration process. The properties of molten HCO and melt agglomerates were dependent on the type and concentration of sucrose stearate added. 相似文献
3.
4.
5.
6.
7.
INVOLVEMENT OF NON-NMDA AND NMDA RECEPTORS IN GLUTAMATE-INDUCED PRESSOR OR DEPRESSOR RESPONSES OF THE PONS AND MEDULLA 总被引:1,自引:0,他引:1
SY Chen WC Wu CJ Tseng JS Kuo CY Chai 《Clinical and experimental pharmacology & physiology》1997,24(1):46-56
1. Fifty-five intact and six baroreceptor denervated and vagotomized cats of either sex were anaesthetized intraperito-neally with urethane (400 mg/kg) and a-chloralose (40 mg/kg). Responses of the systemic arterial pressure (SAP), mean SAP (MSAP) and sympathetic vertebral nerve (VNA) and renal nerve activities (RNA) were recorded. 2. In intact animals, monosodium L-glutamate (Glu, 0.1 mol/L, 50 nL) was microinjected into pressor areas of the locus coeruleus (LC), gigantocellular tegmental field (GTF), rostral ventrolateral medulla (RVLM) and dorsomedial medulla (DM), and the depressor areas of caudal ventrolateral medulla (CVLM). The induced actions were compared before and after microinjection of either glutamate antagonists, glutamate diethylester (GDEE, 0.5 mol/L, 50–100nL), a competitive AMPA receptor blocker, or 2-amino-5-phosphonovaleric acid (D-AP5, 0.025 mol/L, 50–100 nL), a competitive N-methyl-D-aspartate (NMDA) receptor blocker. GDEE completely blocked the increases of SAP and VNA elicited from all pressor areas. D-AP5 only partially blocked the pressor but slightly blocked VNA and RNA responses from LC, GTF and DM, particularly those from RVLM. Neither GDEE nor D-AP5 blocked the depressor responses of SAP and two nerve activities elicited from CVLM. 3. In baroreceptor denervated animals, NMDA (2 mmol/L, 50–100 nL) and AMPA (0.2 mmol/L, 50–100 nL) were micro-injected into the same pressor areas of GTF, RVLM and DM and the depressor area of CVLM responsive to Glu activation (0.1 mol/L, 30 nL). In RVLM, DM and CVLM, the results of either NMDA or AMPA were similar to those induced by Glu. However, in GTF, microinjection of either NMDA or AMPA did not induce similar responses to Glu. This suggests that the nature of GTF may differ from RVLM and DM. 4. The above results suggest that the Glu-induced pressor responses from LC, GTF, DM and especially RVLM, are primarily mediated through AMPA receptors. The Glu-induced depressor responses from CVLM may not be predominantly mediated by either AMPA or NMDA receptors. 5. In both baroreceptor-intact and -denervated cats stimulation of the pressor areas often produced an increase of VNA and a decrease of RNA, while in the depressor CVLM decreased both VNA and RNA. The VNA, but not RNA were positively correlated with the pressor responses, while both VNA and RNA were positively correlated with the depressor responses. This may suggest that neurons of the sympathetic vertebral and renal nerves are topographically organized in the brain. 相似文献
8.
9.
10.
Digital radiography of subtle pulmonary abnormalities: an ROC study of the effect of pixel size on observer performance 总被引:3,自引:0,他引:3
Forty conventional radiographs with examples of mild interstitial infiltrates and subtle pneumothoraces and 40 normal studies of the chest were selected and digitized, with pixel sizes of 1.0, 0.5, 0.2, and 0.1 mm. Observer performance tests were carried out using receiver operating characteristic analysis. Conventional radiographs and digitized images were compared. The results indicate that, in such cases, diagnostic accuracy increases significantly as the pixel size is reduced, at least to the 0.1-mm level. We conclude that, for digital systems using screen-film or similar image receptors, use of a pixel size substantially larger than 0.1 mm may result in some loss of diagnostic accuracy. 相似文献