全文获取类型
收费全文 | 13216篇 |
免费 | 1338篇 |
国内免费 | 310篇 |
专业分类
耳鼻咽喉 | 99篇 |
儿科学 | 234篇 |
妇产科学 | 115篇 |
基础医学 | 1274篇 |
口腔科学 | 128篇 |
临床医学 | 2400篇 |
内科学 | 1394篇 |
皮肤病学 | 85篇 |
神经病学 | 1360篇 |
特种医学 | 186篇 |
外国民族医学 | 1篇 |
外科学 | 540篇 |
综合类 | 2201篇 |
一般理论 | 5篇 |
预防医学 | 1639篇 |
眼科学 | 112篇 |
药学 | 735篇 |
34篇 | |
中国医学 | 2087篇 |
肿瘤学 | 235篇 |
出版年
2024年 | 81篇 |
2023年 | 277篇 |
2022年 | 623篇 |
2021年 | 722篇 |
2020年 | 625篇 |
2019年 | 539篇 |
2018年 | 441篇 |
2017年 | 602篇 |
2016年 | 562篇 |
2015年 | 540篇 |
2014年 | 1048篇 |
2013年 | 1187篇 |
2012年 | 867篇 |
2011年 | 961篇 |
2010年 | 726篇 |
2009年 | 643篇 |
2008年 | 646篇 |
2007年 | 562篇 |
2006年 | 485篇 |
2005年 | 382篇 |
2004年 | 328篇 |
2003年 | 282篇 |
2002年 | 198篇 |
2001年 | 193篇 |
2000年 | 189篇 |
1999年 | 150篇 |
1998年 | 114篇 |
1997年 | 118篇 |
1996年 | 96篇 |
1995年 | 77篇 |
1994年 | 60篇 |
1993年 | 60篇 |
1992年 | 67篇 |
1991年 | 35篇 |
1990年 | 44篇 |
1989年 | 31篇 |
1988年 | 37篇 |
1987年 | 28篇 |
1986年 | 33篇 |
1985年 | 29篇 |
1984年 | 26篇 |
1983年 | 22篇 |
1982年 | 18篇 |
1981年 | 18篇 |
1980年 | 17篇 |
1978年 | 15篇 |
1977年 | 11篇 |
1976年 | 9篇 |
1975年 | 6篇 |
1974年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
P. Greminger W. Vetter H. Groth T. Lüscher W. Tenschert W. Siegenthaler Prof. H. H. Vetter 《Journal of molecular medicine (Berlin, Germany)》1984,62(18):855-858
Summary To analyse the role of the renin angiotensin system in the pathogenesis of hypertension in Cushing's syndrome ten patients with hypercorticism (five with pituitary hypothalamic dysfunction, three with adrenal adenomas and two with adrenal carcinomas) received a single oral dose of 25 mg captopril. Mean arterial pressure was then determined at short intervals over periods of up to 240 min. Plasma renin activity (PRA) was measured immediately before the administration of captopril. Eleven patients with severe essential hypertension, who showed a comparable distribution of basal PRA values, served as a control. Patients with elevated basal PRA values (>3 ng/ml·3 h) showed, both in the subgroup of cases with essential hypertension and in that with Cushing's syndrome, a statistically significant fall (P<0.05–P<0.001) in mean arterial pressure, the decrease being slightly more pronounced in essential hypertensives. On the other hand patients with normal PRA values (3 ng/ml·3 h) exhibited only a minor fall in mean arterial pressure reaching statistical significance (P<0.05) only after 60 min (essential hypertension) and 180 min (Cushing's syndrome), respectively. Our results document that in patients with Cushing's syndrome the effect of captopril seems to be determined by the activity of the renin angiotensin system. Thus, in a substantial number of patients with hypercorticism, the renin angiotensin system may be an important factor in the pathogenesis of hypertension, whereas in patients with low PRA values other factors like oversecretion of mineralocorticoids may be responsible for the observed blood pressure increases. 相似文献
82.
磷脂双层膜稳定性的理论分析 总被引:2,自引:0,他引:2
目的:越来越多磷脂双层膜的原子力显微镜扫描力谱显示溶液离子浓度对磷脂双层膜稳定性有很大影响,本文从理论角度研究溶液离子浓度对磷脂双层膜稳定性的影响,同时解释两个基于不同模型模拟结果差别的原因。方法:主要根据磷脂分子极性端带电特性,将极性端看作偶极子,然后基于偶极-偶极相互作用理论以及泊松-玻尔兹曼理论解决以上问题。结论:随着离子浓度的增加,磷脂双层膜趋于更加稳定;基于两个不同模型模拟结果差别的原因是高浓度溶液的强静电屏蔽作用。 相似文献
83.
The relationship between cardiac activity and sensory acuity suggested by Lacey and Lacey was tested by recording heart rates of Ss attempting to detect a threshold-level visual stimulus. Heart rate decelerations during a warning tone preceding the threshold stimulus were found in be greater on hit trials than on miss trials, supporting the suggested relationship. 相似文献
84.
病毒性心肌炎小鼠心肌组织中趋化因子表达谱的改变及其意义 总被引:7,自引:0,他引:7
目的:研究病毒性心肌炎(VMC)小鼠心肌组织趋化因子(ChKs)表达谱变化,探讨ChKs在VMC发病中的可能作用及意义。方法:B3型柯萨奇病毒(CVB3)腹腔注射雄性BALB/c小鼠;RTPCR定性和定时定量分析心肌组织MCP-1、IP-10、Ltn和FKN等12种ChKs表达。病理切片和血清CKMB分析判定病变和病程程度。结果:(1)在所检测的12种ChKs中,VMC组呈阳性表达的有9种,显著多于正常组心肌组织的6种,有3种ChKs(BLC、Eot和LARC)两组均未检出;(2)VMC组9种阳性表达的ChKs中CVB3诱导性表达的为MIP-2、MIG和IP-10,6种组成性表达的ChKs在VMC时上调表达的有MIP-1β、MCP-1、MCP-2、Ltn等4种,下调表达的有RANTES,与正常对照组比未呈现明显差异的为FKN。(3)ChKs的表达消长存在一定的差异,感染4d后MIP-2等达高峰,随后下降;9d后出现MCP-1和RANTES表达上升峰;FKN在感染9d内表达较稳定。(4)亚急性早期、中期、中后期和晚期心肌组织ChKs表达谱有明显区别,各期ChKs表达谱中优势表达的ChKs分别为IP-10、IP-10、MCP-1、MCP-1。结论:VMC心肌组织ChKs呈成簇性方式改变,表达谱改变的复杂性可能与发病机制的复杂性有关,优势表达的ChKs可能在病毒性心肌炎发病中扮演着更重要的角色。 相似文献
85.
86.
多参数信息融合实现非脑电的睡眠结构分期 总被引:7,自引:3,他引:7
目前临床睡眠分析的主要手段是多导睡眠图(Polysomnograph,PSG),用仪器记录被测者整晚的脑电、眼动电和颏肌电等生理参数,计算机进行自动睡眠分期,再由技术人员依据国际标准进行校正.几十年来PSG保持着睡眠分期金标准的地位.提出在不使用脑电的条件下,利用较易获得的心动周期、呼吸、体动等基本生理参数,提取其中与睡眠过程及其变化有关的规律和信息,建立知识规则库,采用不确定推理的证据理论进行多参数睡眠信息融合计算,实现睡眠结构分期.50余例与PSG对照试验结果表明:醒睡的平均符合率达90%以上,基本睡眠结构的平均符合率达75%以上,证明该技术达到了应用的要求. 相似文献
87.
The main purpose of the study was to compare the efficiency of the Fishbein and Ajzen and the Triandis models to predict (1) the intention to participate regularly in some physical activities during free time within a 3-week period and (2) the exercise behavior within these 3 weeks among a group of 166 subjects, aged 22 to 65 years. Our results show that the Triandis model was as efficient as the Fishbein and Ajzen model in predicting the exercise behavior. However, the results obtained from the Triandis model demonstrate the importance of the habit of exercising in predicting the exercise behavior. Moreover, the Triandis model was superior to the Fishbein and Ajzen model in explaining behavioral intention. Of particular interest was the salience of the affective, social, and personal belief components of the Triandis model. In addition, from a practical perspective, this comparative study showed that (1) to exercise regularly is perceived as hard work, and (2) individuals believe that it is their own responsibility to exercise or not to exercise. 相似文献
88.
任务的呈现方式对孤独症儿童误念理解的影响 总被引:6,自引:0,他引:6
目的:探讨一种更适于测试孤独症儿童误念理解能力的方法.方法:2(呈现方式)×2(被试类型)设计,采用经典误念任务,使用计算机多媒体动画呈现方式与传统图片-实物呈现方式,分别测试20名孤独症儿童和言语能力(PPVT-R)匹配的正常儿童.结果:呈现方式的主效应非常显著(P<0.001),动画呈现方式使正常儿童和孤独症儿童的误念理解成绩都有提高,孤独症儿童的提高更大.结论:孤独症儿童的误念理解能力在误念任务的传统呈现方式之下可能被低估了.充分考虑孤独症认知缺陷的多样性,使用恰当的任务方式,可能会更真实地反映他们的心理理论发展水平. 相似文献
89.
Robert L. Rubinstein 《Journal of cross-cultural gerontology》1987,2(1):1-14
Almost nothing is concretely known about childless elderly in cross-cultural perspective. Few published papers have appeared on this social category in the West, although childless elders make up (at least) 20% of the population of elderly in many Western nations. Little is known about childless elderly in the Third World. This paper provides some theoretical background to the study of childless elderly and articulates some social policy concerns about them. It suggests that there are five important questions to examine concerning the lives of childless elderly. These include, how childless aged are or are not provided for in societies in which a great deal of the care of the aged is undertaken by children; how kinship functions as a matrix for care; how the increasingly common phenomenon of voluntary childless may give meaning to childlessness in late life; how childlessness fits with such social science models such as the developmental cycle; and, the relationship of this phenomenon to changing opportunities for women. The paper further examines how factors such as fertility, systems of caregiving, the social meaning of childlessness, alternatives to childlessness such as adoption, and educational and economic opportunities may affect the lives of childless elders. 相似文献
90.
Radiographic quantification of alveolar bone level changes 总被引:3,自引:0,他引:3
Jasim M. Albandar Jostein Rise Per Gjermo Jan R. Johansen 《Journal of clinical periodontology》1986,13(3):195-200
The "random burst" theory has recently been proposed as an explanation of the pattern of periodontal disease progression. The theory predicts that the progression of bone loss at individual sites is not dependent upon previous bone loss and age. A longitudinal radiographic study was designed to test this hypothesis, and to describe the changes in bone level over 2 years in a group of 180 subjects (18-68 years of age) who were not under systematic periodontal treatment. The results indicated that 94% of the sites did not show significant changes in the alveolar bone level during the observation period. The mean annual bone loss for the total population was 0.11 mm. By regressing longitudinal bone loss upon age, it was shown that the rate of bone loss increased rapidly between 33 and 56 years of age while a different pattern was shown for the age intervals 18-32 and 57-68 years. Also, the rate of bone loss increased with increasing initial bone loss. This was less evident in the oldest age group. It was concluded that the progression of bone loss in the present material is consistent with a "burst" theory. However, the progression did not occur randomly with regard to previous loss of alveolar bone and time. 相似文献