全文获取类型
收费全文 | 14431篇 |
免费 | 825篇 |
国内免费 | 212篇 |
专业分类
耳鼻咽喉 | 62篇 |
儿科学 | 125篇 |
妇产科学 | 61篇 |
基础医学 | 1601篇 |
口腔科学 | 267篇 |
临床医学 | 1173篇 |
内科学 | 2078篇 |
皮肤病学 | 250篇 |
神经病学 | 3012篇 |
特种医学 | 465篇 |
外国民族医学 | 1篇 |
外科学 | 1208篇 |
综合类 | 1282篇 |
预防医学 | 1801篇 |
眼科学 | 271篇 |
药学 | 1130篇 |
5篇 | |
中国医学 | 449篇 |
肿瘤学 | 227篇 |
出版年
2024年 | 43篇 |
2023年 | 332篇 |
2022年 | 492篇 |
2021年 | 705篇 |
2020年 | 634篇 |
2019年 | 701篇 |
2018年 | 594篇 |
2017年 | 386篇 |
2016年 | 381篇 |
2015年 | 369篇 |
2014年 | 872篇 |
2013年 | 745篇 |
2012年 | 711篇 |
2011年 | 800篇 |
2010年 | 662篇 |
2009年 | 633篇 |
2008年 | 621篇 |
2007年 | 623篇 |
2006年 | 505篇 |
2005年 | 402篇 |
2004年 | 354篇 |
2003年 | 330篇 |
2002年 | 279篇 |
2001年 | 233篇 |
2000年 | 216篇 |
1999年 | 190篇 |
1998年 | 190篇 |
1997年 | 167篇 |
1996年 | 166篇 |
1995年 | 144篇 |
1994年 | 138篇 |
1993年 | 141篇 |
1992年 | 135篇 |
1991年 | 132篇 |
1990年 | 133篇 |
1989年 | 105篇 |
1988年 | 105篇 |
1987年 | 110篇 |
1986年 | 124篇 |
1985年 | 193篇 |
1984年 | 142篇 |
1983年 | 106篇 |
1982年 | 89篇 |
1981年 | 84篇 |
1980年 | 68篇 |
1979年 | 55篇 |
1978年 | 24篇 |
1977年 | 41篇 |
1976年 | 21篇 |
1973年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
71.
Corrado Corti Luca Crepaldi Silvia Mion Adelheid L Roth John H Xuereb Francesco Ferraguti 《Neuropsychopharmacology》2007,62(7):747-755
BACKGROUND: Metabotropic glutamate receptors (mGlus) may be involved in the pathophysiology of schizophrenia. Group II mGlus (mGlu2 and mGlu3) have attracted considerable interest since the development of potent specific agonists that exhibit atypical antipsychotic-like activity and reports of a genetic association between the mGlu3 gene and schizophrenia. METHODS: In this postmortem study, mGlu3 protein levels in Brodmann area 10 of prefrontal cortex from schizophrenic (n = 20) and control (n = 35) subjects were analyzed by western immunoblotting using a novel specific mGlu3 antibody and an antibody for the vesicular glutamate transporter 1 (VGluT1). RESULTS: We report a significant decrease in the dimeric/oligomeric forms of mGlu3 in schizophrenic patients compared with control subjects, whereas total mGlu3 and VGluT1 levels were not altered significantly. CONCLUSIONS: This is the first experimental evidence that mGlu3 receptor levels are altered in schizophrenia and supports the hypothesis that neurotransmission involving this particular excitatory amino acid receptor is impaired in schizophrenia. 相似文献
72.
Lester M. Arguelles Xiaobin Wang Binyan Wang Hakan Demirtas Jianhua Yang Zhiping Li Liuliu Wang Xue Liu Genfu Tang Houxun Xing Xiping Xu 《Archives of osteoporosis》2007,2(1-2):7-20
Introduction This report examines the relationship of body mass index (BMI), percent body fat (%BF), and bone mass in a cohort of male
and female twins recruited from Anhui province, China, ages 6–18 years—577 male pairs (mean age = 11.4) and 478 female pairs
(mean age = 11.6).
Methods Whole body bone mineral content (WBMC) in (g), whole body bone area (WBA) in (cm2), and %BF were measured using DEXA (Lunar Prodigy, USA). Regression analysis of within-pair differences was used to assess
the strength of the association, and the analysis was stratified by gender and age group, where age cut-offs were based on
ages at spermarche or menarche estimated from large population based studies in China. Males were stratified at ages before
14 and age 14–18, and females at ages prior to 12 and age 12–18.
Results Univariately, BMI and %BF were associated with WBMC and WBA in the younger males and females, and in older males; %BF was
significant only in older females. Multivariate models included both BMI and %BF. Among the younger males, age < 14, BMI and
%BF were significantly associated with WBMC and WBA. In the younger females, age < 12, %BF was only significant to WBA. In
the older age group, only BMI was significant to WBMC and WBA in females, but in males, BMI was positively associated, and
%BF was negatively associated with both bone measures.
Discussion These findings show that association between BMI and %BF and bone mass differ across gender and developmental stages, and
%BF appears to be beneficial at younger ages, but detrimental or non-beneficial at older ages of development. 相似文献
73.
T Fikrle K Pizinger 《Journal of the European Academy of Dermatology and Venereology》2007,21(1):48-55
BACKGROUND: Digital computer analysis of dermatoscopical images has been reported to facilitate the differential diagnosis of pigmented skin lesions in recent years. OBJECTIVE: The aim of our study was to perform digital computer analysis of a set of different melanocytic lesions and compare the objective results. METHODS: The set of 260 melanocytic lesions (150 excised difficult cases (46 melanomas, 47 atypical nevi, 57 common nevi and 110 unexcised common nevi) was automatically analysed by the digital dermatoscopical system microDERM. We searched for differences in asymmetry, size, compactness and colour distribution. Perimeter/area ratio was calculated. RESULTS: The perimeter/area ratio was detected as the most important criterion for differentiation between malignant and benign melanocytic lesions (sensitivity 91.3% and specificity 90.7% for malignant melanomas vs. all benign nevi; sensitivity 91.3% and specificity 80.8% for melanomas vs. clinically atypical nevi). Differences in size of the lesion, shape and asymmetry of colour were found and statistically verified. Using step-wise logistic regression the formula for calculation of probability of malignant nature of every analysed lesion was constructed. CONCLUSION: The perimeter/area ratio is a simple parameter for the differential diagnosis of melanocytic skin lesions. 相似文献
74.
75.
76.
We have investigated the distribution of vasopressin binding sites in the brain of male and female adult mice using a radio-iodinated ligand and film autoradiography. Vasopressin receptors were uncovered in various regions of the brain including the basal nucleus of Meynert, the substantia innominata, the hypothalamic paraventricular nucleus, the substantia nigra pars compacta and the hypoglossal nucleus. A sex-related difference in the expression of vasopressin receptors was seen in the medial preoptic area/anterior hypothalamus corresponding to the rat sexually dimorphic nucleus in the rat and in the hypothalamic mammillary nuclei. In both structures the autoradiographic labeling is more intense in females than in males. These observations confirm that vasopressin binding sites are present in the hypothalamic preoptic area of most species examined so far and that sex-related expression of neuropeptide receptors could trigger sex-related behavioral differences. 相似文献
77.
K. ROELEVELD D. F. STEGEMAN H. M. VINGERHOETS A. VAN OOSTEROM 《Acta physiologica (Oxford, England)》1997,160(2):175-183
The background of the bioelectric activity of muscle recorded from the surface of the skin (surface electromyography) in terms of the representation of single motor units of the underlying muscle(s) is not very well documented or understood. An insight into the composition of an electromyogram is essential for the proper interpretation of one of the most widely applied electrophysiological techniques. In the present paper, a study of the contribution of single motor unit potentials to the surface electromyogram is presented. To this end, the decline of different components of the motor unit potential with depth of the motor unit is quantified. Experimentally, the action potentials from motor units at several positions in the muscle were recorded by 30 skin surface electrodes. Simultaneous use of scanning electromyography provided information about the actual position and size of the motor unit. Observed linear log–log relationships between motor unit potential magnitudes and distance indicated the usefulness of a power function to describe the motor unit potential's dependence on recording distance. It is shown that different specific surface motor unit potential characteristics fall off differently with depth. The magnitude–distance relationship is shown to be dependent on the recording configuration (unipolar vs. bipolar recording, including the inter-electrode distance) and the chosen motor unit potential parameter (negative peak amplitude, positive peak amplitude and area). 相似文献
78.
Anne-Marie Francois-Bellan Micheline Hery Maxime Faudon Francis Hery 《Journal of neuroendocrinology》1989,1(6):415-422
The purpose of this study was to test the capacity of oestradiol to modulate the stimulating effect of a-aminobutyric acid (GABA) on serotonin (5-HT) metabolism, previously described in the Suprachiasmatic area of the male rat. After an in vivo stimulation of GABA transmission by systemic administration of a GABA-transaminase inhibitor (amino-oxyacetic acid) or a GABAB agonist (RS-baclofen), the 5-HT metabolism was studied in the Suprachiasmatic area of ovariectomized, and ovariectomized oestradiol-treated rats. Amino-oxyacetic acid or RS-baclofen treatment increased the endogenous content of 5-HT in the Suprachiasmatic area of males and ovariectomized rats. These two treatments were without effect in ovariectomized oestradiol-treated rats. GABA transmission stimulation induced by amino-oxyacetic acid treatment failed to affect the release and synthesis of 5-HT in ovariectomized oestradiol-treated rats while it increased these two parameters of 5-HT metabolism in the Suprachiasmatic area of male and ovariectomized rats. To investigate the main target of oestradiol effect, comparative studies of the serotoninergic and GABAergic metabolism in the Suprachiasmatic area were performed in the three experimental groups. Under our experimental conditions the endogenous 5-HT metabolism was similar between ovariectomized and ovariectomized oestradiol-treated rats. Nevertheless, 5-HT metabolism was higher in the two female groups than in the male group. Neither GABA metabolism nor GABAergic response to GABA-related drug treatment differed between ovariectomized, and ovariectomized oestradiol-treated rats. However, the turnover of GABA was higher when compared to the two female groups. It is concluded that the lack of 5-HT responsiveness to GABA transmission stimulation in ovariectomized oestradiol-treated rats was not related to an effect of oestradiol on 5-HT metabolism or to an effect of the steroid on GABA turnover. Furthermore, our results suggest a sex difference in the activity of serotoninergic and GABAergic systems in the Suprachiasmatic area. 相似文献
79.
John M. Meredith Catherine J. Auger Jeffrey D. Blaustein 《Journal of neuroendocrinology》1994,6(6):639-648
Low amplitude pulses of estradiol-17β (E2-17β) are more effective than large single bolus injections or constant exposure to E2-17β in inducing progesterone-facilitated sex behavior in female rats and guinea pigs. The present study examined whether the increased responsiveness to E2-17β is due to an increase in the number of estrogen receptors in the estrogen receptor rich areas of the hypothalamus and amygdala. Initial studies examined the rapid effects (20 min) of a high dose of E2-17β (50 μg) on estrogen receptor immunostaining using either the H222 antibody or the ER 21 antiserum. ER 21 immunostaining was not affected by the E2-17β treatment suggesting that it binds to both occupied and unoccupied estrogen receptors. Therefore the ER 21 antiserum was used to characterize the regulation of estrogen receptor immunoreactivity (ER-IR) by E2-17β. ER-IR was examined for 48 h and serum E2-17β for 24 h following a 2 μg s.c. injection of E2-17β (a dose similar to that used in multiple pulse paradigms). Serum E2-17β peaked 15 to 30 min following the injection and returned to baseline values by 1 h. In all but one area maximal suppression of ER-IR occurred at 12 h. In summary, 1) decreases in estrogen receptor immunoreactivity following E2-17β are consistent with studies in which estrogen receptors were assayed by binding assays and estrogen receptor mRNA was determined by in situ hybridization; 2) the ER 21 antiserum is able to detect both occupied and unoccupied estrogen receptors and 3) H222 immunoreactivity is influenced by the presence of E2-17β, so that the level of H222-IR is a reflection of ligand/receptor binding dynamics. The data suggest that up-regulation of estrogen receptors does not account for the increase in behavioral sensitivity which is observed following multiple pulses of E2-17β. 相似文献
80.
鞍区肿瘤术后中枢性低钠血症的诊断和治疗 总被引:2,自引:1,他引:1
目的:探讨鞍区肿瘤术后中枢性低钠血症的诊断及处理方法。方法:对我科近四年鞍区肿瘤术后并发中枢性低钠血症的58例患者进行回顾性分析,术前、手术当日及术后每日定时检测血钠,观察尿量变化,测定中心静脉压,确定低钠血症的类型并给予相应的处理。结果:56例恢复正常,1例死于严重肺部感染,1例自动出院。结论:鞍区肿瘤易出现抗利尿激素分泌不当综合症和脑性耗盐综合症两种类型。前者需限水治疗,后者应予以充分补钠、补水,根据水、钠检测水平治疗。 相似文献