全文获取类型
收费全文 | 18146篇 |
免费 | 943篇 |
国内免费 | 111篇 |
专业分类
耳鼻咽喉 | 319篇 |
儿科学 | 289篇 |
妇产科学 | 156篇 |
基础医学 | 2031篇 |
口腔科学 | 603篇 |
临床医学 | 1179篇 |
内科学 | 4256篇 |
皮肤病学 | 330篇 |
神经病学 | 1363篇 |
特种医学 | 1023篇 |
外科学 | 3184篇 |
综合类 | 84篇 |
预防医学 | 452篇 |
眼科学 | 481篇 |
药学 | 1377篇 |
中国医学 | 27篇 |
肿瘤学 | 2046篇 |
出版年
2023年 | 86篇 |
2022年 | 237篇 |
2021年 | 394篇 |
2020年 | 239篇 |
2019年 | 345篇 |
2018年 | 428篇 |
2017年 | 316篇 |
2016年 | 392篇 |
2015年 | 363篇 |
2014年 | 490篇 |
2013年 | 588篇 |
2012年 | 1013篇 |
2011年 | 1035篇 |
2010年 | 609篇 |
2009年 | 497篇 |
2008年 | 948篇 |
2007年 | 948篇 |
2006年 | 1027篇 |
2005年 | 916篇 |
2004年 | 855篇 |
2003年 | 772篇 |
2002年 | 847篇 |
2001年 | 503篇 |
2000年 | 516篇 |
1999年 | 516篇 |
1998年 | 255篇 |
1997年 | 197篇 |
1996年 | 170篇 |
1995年 | 154篇 |
1994年 | 130篇 |
1993年 | 113篇 |
1992年 | 324篇 |
1991年 | 286篇 |
1990年 | 301篇 |
1989年 | 320篇 |
1988年 | 257篇 |
1987年 | 262篇 |
1986年 | 230篇 |
1985年 | 221篇 |
1984年 | 150篇 |
1983年 | 98篇 |
1982年 | 53篇 |
1981年 | 67篇 |
1979年 | 86篇 |
1978年 | 58篇 |
1977年 | 50篇 |
1972年 | 46篇 |
1971年 | 48篇 |
1970年 | 48篇 |
1969年 | 55篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Vasundhara Sridharan Yuichi Shoda Jaimee L. Heffner Jonathan Bricker 《Substance use & misuse》2019,54(7):1086-1095
Background: Lay belief systems about the malleability of human attributes have been shown to impact behavior change in multiple domains. Addiction mindset—i.e., beliefs about the permanence (vs. malleability) of addiction — may affect cigarette smokers’ ability to quit, but this has never been examined. Objectives: The aims of the present research were to develop a measure of addiction mindset (study 1) and examine its associations with various psychological aspects of quitting smoking (study 2). Methods: In Study 1, using factor analysis of current smokers’ and nonsmokers’ (n?=?600) responses to 22 items designed to measure addiction mindset, we developed a reliable six-item Addiction Mindset Scale (AMS). In Study 2, adult smokers (n?=?200) completed the AMS, and measures of a number of psychological processes related to smoking. Results: Higher scores on the AMS, indicative of the belief that addiction is malleable (referred to as a growth mindset), were positively and significantly associated with greater motivation to quit, greater commitment to quitting, greater self-efficacy to abstain, less attribution of failure to lack of ability to change addiction, and fewer self-reported barriers to cessation (all p’s < .05). Conclusions: The results of this study show a relationship between the beliefs about the permanence of addiction and psychological processes relevant to quitting smoking. The findings underscore the potential of future research exploring how addiction mindsets relate to successful smoking cessation as well as other types of addictive behavior and how they can be applied to change people’s behavior. 相似文献
2.
3.
Taisuke Inada Satoshi Fukushima Masayuki Murai Masatoshi Jinnin Azusa Miyashita Satoshi Nakahara Junji Yamashita Jun Aoi Shinichi Masuguchi Hironobu Ihn 《The Journal of dermatology》2015,42(2):198-201
miRNA‐221 (miR‐221) is known to be abnormally expressed in many human cancers. The serum levels of miR‐221 have been reported as a tumor marker for malignant melanoma (MM). We hypothesized that the hair shaft miR‐221 levels may be increased in patients with MM. We therefore assessed the possibility that hair shaft miR‐221 levels could be a marker for MM. The hair shaft miR‐221 levels were significantly higher in patients with MM than controls. The rates of increased hair shaft miR‐221 levels above the cut‐off value were comparable to those of serum 5‐S‐CD, which is a tumor marker commonly used for MM. Measurements of the hair shaft miR‐221 levels could have potential clinical value in the detection of MM. This is the first report investigating the hair shaft levels of an miRNA in patients with MM. Our investigations offer new insight into the relationship between miR‐221 and MM, and may provide a new, non‐invasive way to screen for melanoma. 相似文献
4.
We examined stochastic resonance with a differential coding scheme using a multilayer feedforward neural network which is composed of intra-layer connections. We show that the network, with random synaptic connections in each layer, encodes an input signal into a spike coherence that represents temporal differences among the inputs. We also demonstrate that both internal and external noise enhance the detection of weak signals. Finally, we discuss how the feedforward network with intra-layer random connections is similar to a membrane in its sensitivity to and amplification of a change in stimulus and suggest that the intensity of internal noise may be tuned in a real brain. 相似文献
5.
Nobuaki Yanagisawa Shinichi Abe Hiroko Agematsu Koji Sakiyama Akinobu Usami Yuichi Tamatsu Yoshinobu Ide 《Annals of anatomy》2006,188(4):329-336
To elucidate the effects of teeth on muscle fibers in the tongue during the developmental process, we examined the expression of muscle contractile proteins and the genes for those proteins in normal mice and microphthalmic (mi/mi) mice with impaired tooth eruption. The mice were observed during the growth period, including weaning, which is when feeding movements undergo major changes. Expression of the myosin heavy chain (MyHC)-2a protein, whose contraction speed is relatively slow, disappeared after weaning in normal mice, while it remained in high concentrations even after weaning in mi/mi mice. The presence of MyHC-2a after weaning in mice with no tooth eruption was attributed to a compensation for lack of proper masticatory function and sucking-like movements, as MyHC-2a is necessary for these movements. 相似文献
6.
Y Nishizawa T Shoji S Tanaka M Yamashita A Morita M Emoto T Tabata T Inoue H Morii 《American journal of kidney diseases》1998,31(4):655-661
Leptin is a newly found hormone secreted by adipocytes that regulates food intake, thermogenesis, and body fat. We measured plasma leptin levels in 103 patients with chronic renal failure treated by hemodialysis and 167 age- and gender-matched healthy control subjects to examine the impact of renal failure on plasma leptin levels and the influence of leptin on body composition measured by dual-energy X-ray absorptiometry. Hemodialysis patients showed a significant decrease in both body fat mass and lean body mass compared with those of the control subjects. Plasma leptin was significantly elevated in the hemodialysis group over the controls. In both groups, leptin was higher in female than male subjects, and it correlated positively with percent body fat. The subjects were divided into six categories according to percent body fat, and plasma leptin levels were compared between the two groups in the same category. Leptin of hemodialysis patients was significantly higher than that of the control subjects in the percent body fat categories of 30 or greater, whereas there was no statistically significant difference in leptin concentrations in the lower percent body fat categories. This was also true in the comparison in each gender, and leptin levels in female subjects showed a more remarkable difference between the hemodialysis and control groups in obese categories. Multiple regression analysis in all subjects indicated that plasma leptin levels were independently affected by percent body fat, plasma insulin concentration, gender, and renal failure. The positive impact of renal failure on leptin remained significant in the subjects with percent body fat of 30 or greater in the multiple regression model, whereas it was no longer significant in the remaining lean subjects. In multiple regression analysis of factors affecting fat mass index and lean mass index, leptin level was selectively associated with fat mass index, but not with lean mass index, regardless of percent body fat ranges. These results indicate that renal failure is an important factor affecting plasma leptin levels, especially in obese female subjects, and that hyperleptinemia was closely related to fat mass but not to lean body mass in hemodialysis patients. 相似文献
7.
M Yoshino Y Sakaguchi N Kuriya Y Ohtani F Yamashita T Hashimoto K Oyanagi K Tada K Narisawa T Kitagawa 《Neuropediatrics》1991,22(4):198-202
A nationwide survey of transient hyperammonemia in newborns was carried out in Japan. A total of 18 patients, consisting of 12 male and 6 female infants, were reported from 11 facilities. These neonates exhibited hyperammonemia with plasma ammonia levels in the range from 124 to 6256 micrograms/dl. Four newborn infants of the 18 died in the neonatal period, and an additional one died in the early infancy. Among the 13 infants who were alive at the time of this survey, 6 had neurological sequelae, including mental retardation, spastic quadriplegia and epilepsy. The multivariate analysis revealed that the Apgar score at 1 minute, peak plasma ammonia concentration, birth weight and sex were significant factors affecting the prognosis of life. 相似文献
8.
9.
Intraventricular hemorrhage (IVH) in preterm infants is well known to be associated with the high morbidity and mortality of this group. Previous studies have suggested altered cerebral blood flow (CBF) as an important pathologic factor. We measured the CBF in nearterm rabbit fetuses using the hydrogen clearance technique. The local CBF of the rabbit fetuses was significantly low compared with that of the maternal rabbits. The response of CBF to changes in PaCO2 was observed in rabbit fetuses. The CO2 reactivity index of the fetal rabbit was lower than that of the maternal rabbit. This low CO2 reactivity might reflect the immaturity of the fetal brain and its low CBF. We were unable to monitor the fetal blood pressure, but the fetal CBF remained stable when the maternal blood pressure was altered. It is well known that IVH in preterm infants originates from the subependymal germinal matrix and that this has many fragile vessels. Our observation suggests that even a small increase of CBF during hypercapnia might have a large effect towards producing hemorrhage. 相似文献
10.
Prognostic factors in the treatment of hepatocellular carcinoma with transcatheter arterial embolization and arterial infusion. 总被引:8,自引:0,他引:8
Y Yamashita M Takahashi Y Koga R Saito S Nanakawa Y Hatanaka N Sato K Nakashima J Urata K Yoshizumi 《Cancer》1991,67(2):385-391
From January 1986 to December 1988, a prospective trial of transcatheter arterial treatment was carried out for hepatocellular carcinoma (HCC). Two hundred seventy-five patients were included. Okuda's staging system was employed. Patients with Stage I and II HCC were treated by transcatheter arterial embolization (TAE) with a gelatin sponge containing an anti-cancer agent (protocol 1a); a gelatin sponge and iodized oil mixed with an anti-cancer agent (protocol 1b); or iodized oil mixed with an anti-cancer agent (protocol 2). Patients with Stage III HCC were treated with iodized oil with anti-cancer agent (protocol 2). As an exception, patients with an unsuccessful superselective catheterization into the proper hepatic artery by Seldinger technique or obstruction of the main trunk of the portal vein were treated with percutaneous transcatheter arterial infusion into the common hepatic artery regardless of stage (protocol 3). Tumor type and extension, area of tumor involvement, portal vein involvement, method of treatment, and presence of ascites and icterus were found to be the significant factors for an initial response to therapy. Treatment method was the most important factor. Respective survival rates at 1 and 2 years were 70.9% and 55.3% for protocol 1a; 62.3% and 43.8% for protocol 1b; 37.8% and 18.3% for protocol 2; and 16.5% and 0% for protocol 3. Many factors proved to significantly influenced prognosis; however, tumor type had the most important prognostic significance followed by AFP value, ascites, treatment protocol, and area of tumor involvement. 相似文献