全文获取类型
收费全文 | 20919篇 |
免费 | 1146篇 |
国内免费 | 81篇 |
专业分类
耳鼻咽喉 | 303篇 |
儿科学 | 573篇 |
妇产科学 | 450篇 |
基础医学 | 3014篇 |
口腔科学 | 1458篇 |
临床医学 | 2232篇 |
内科学 | 3984篇 |
皮肤病学 | 438篇 |
神经病学 | 1835篇 |
特种医学 | 413篇 |
外科学 | 1779篇 |
综合类 | 136篇 |
一般理论 | 13篇 |
预防医学 | 2469篇 |
眼科学 | 390篇 |
药学 | 1391篇 |
中国医学 | 115篇 |
肿瘤学 | 1153篇 |
出版年
2024年 | 23篇 |
2023年 | 208篇 |
2022年 | 441篇 |
2021年 | 830篇 |
2020年 | 498篇 |
2019年 | 726篇 |
2018年 | 787篇 |
2017年 | 575篇 |
2016年 | 560篇 |
2015年 | 688篇 |
2014年 | 882篇 |
2013年 | 1123篇 |
2012年 | 1742篇 |
2011年 | 1885篇 |
2010年 | 952篇 |
2009年 | 812篇 |
2008年 | 1372篇 |
2007年 | 1356篇 |
2006年 | 1231篇 |
2005年 | 1098篇 |
2004年 | 916篇 |
2003年 | 854篇 |
2002年 | 812篇 |
2001年 | 181篇 |
2000年 | 140篇 |
1999年 | 125篇 |
1998年 | 155篇 |
1997年 | 101篇 |
1996年 | 82篇 |
1995年 | 74篇 |
1994年 | 72篇 |
1993年 | 60篇 |
1992年 | 63篇 |
1991年 | 80篇 |
1990年 | 68篇 |
1989年 | 43篇 |
1988年 | 36篇 |
1987年 | 37篇 |
1986年 | 44篇 |
1985年 | 42篇 |
1984年 | 36篇 |
1983年 | 35篇 |
1982年 | 36篇 |
1981年 | 31篇 |
1980年 | 30篇 |
1979年 | 36篇 |
1978年 | 17篇 |
1977年 | 17篇 |
1976年 | 16篇 |
1975年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
The aim of the study was to investigate if the stretch reflex of the soleus muscle was useful in quantifying upper motor neuron lesions. The soleus stretch reflex was recorded in 10 healthy subjects and 20 patients with active relapsing-remitting multiple sclerosis and correlated to the number of MRI lesions in cerebrum and clinical scores (expanded disability status scale and regional functional scoring system). The short latency stretch reflex was elicited by rotating the left ankle joint 4 degrees with a rise time in the interval of 40-640 ms. The amplitude of the stretch was larger in multiple sclerosis patients being 88.5 microV in patients and 12.8 microV in controls, P = 0.007. The sensitivity of the stretch reflex expressed as the slope of the best linear fit was increased in MS patients to 2.6 microVs/degree compared with 0.6 microVs/degree (0.1-2.2) in controls, P = 0.009. There was no correlation between amplitude of the stretch reflex and number of MRI lesions (r = -0.03). In conclusion, the soleus stretch reflex might be useful to quantify spasticity but is not useful in detecting dysfunction of upper motor neurons in MS. 相似文献
52.
For eating-disordered patients with a history of post-traumatic stress, childhood abuse and neglect, and dissociative disorder, eating behavior symptoms may function as a rational response to unmetabolized traumatic experiences. This paper will review trauma-based theory, dissociation, abreactive, and ego-states therapy as they apply to eating disorder patients. 相似文献
53.
Paula J. Durlach 《Psychopharmacology》1998,140(1):116-119
There is little evidence concerning the effects of caffeine in doses typical of one cup of tea. The present study investigated
the effect of 60 mg caffeine, consumed in either tea or hot water, on performance on a subset of the CANTAB test battery.
Eight males participated in a practice session and four test sessions. In each test session, the participant consumed a different
hot beverage and then, over approximately 90 min, completed nine tests from the CANTAB battery. The four beverages were created
by crossing beverage identity (tea or hot water) and caffeine dose (0 or 60 mg). Significant speeding of reaction time by
caffeine consumption was found in pattern recognition, delayed match to sample, and match to sample visual search. The effect
on reaction time of 60 mg caffeine can be detected, and may be evident within minutes of consumption.
Received: 16 March 1998/Final version: 27 July 1998 相似文献
54.
Activins are members of the transforming growth factor-beta (TGFbeta) superfamily, which regulate cell differentiation processes. Here we report the first quantitative analysis of the expression of Activin/Inhibin ligands, type I and II receptors, as well as Smad proteins in fetal (E14-E16) and adult thymic subpopulations. Our data showed that Alk4, ActRIIA, ActRIIB, and Smads 2, 3, and 4, are expressed in fetal thymus (E14 > E15 > E16) and in thymocytes from adult mice (mostly in the double negative [DN] subpopulation). Ligand expression analysis showed that betaA, betaB, and alpha subunits were mainly detected in thymic stromal cells. Interestingly, alpha subunits were expressed at much higher levels compared to betaA and betaB subunits, demonstrating for the first time the potential role of Inhibins as important mediators during early T cell development. Our data indicate that Activin/Inhibin signaling could regulate the process of thymus organogenesis and early thymocyte differentiation, as it has been demonstrated for other members of the TGF-beta superfamily. 相似文献
55.
Delaugerre C Teglas JP Treluyer JM Vaz P Jullien V Veber F Rouzioux C Chaix ML Blanche S 《Journal of acquired immune deficiency syndromes (1999)》2004,37(2):1269-1275
Predictive factors of the virologic success of the use of lopinavir/ritonavir (LPV/r) in HIV-infected children are unknown, especially in children who have been pretreated with protease inhibitors (PIs). This longitudinal, single-center, observational study included 69 children (21 PI-naive and 48 PI-experienced) who had received LPV/r for at least 3 months. The mean (+/- SD) age was 10.3 +/- 4.8 years, and the mean baseline of CD4 percentage and HIV-1 RNA was 14.9% +/- 9.8% and 4.8 +/- 1.05 log10 copies/mL, respectively. The mean duration of follow-up was 16.5 +/- 8.3 months. At 6, 12, and 18 months, 52%, 57%, and 49% of all children, respectively, had a viral load less than 50 copies/mL. The risk of virologic failure, defined as 2 consecutive viral loads greater than 1000 copies/mL, was significantly higher when the children were previously treated with PIs and when the baseline LPV mutation score exceeded 3 mutations. In the pretreated children, the ratio of the plasma LPV maximal concentration to the baseline LPV score mutation was also associated with failure, independently of resistance score. Finally, in children failing an LPV-containing regimen, accumulation of additional PI-associated resistance mutations was evidenced in viral isolates from children with prior PI treatment, even with viral replication levels less than 10,000 copies/mL. In pretreated children, LPV plasma levels should be optimized in an attempt to achieve sufficient drug concentrations to overcome the resistance level. 相似文献
56.
57.
58.
Neoplastic cells generally present profound changes in glucose metabolism. The mechanisms underlying such process are numerous and all may involve altered cellular hormonal responses. Here we report the first evidence that cellular location of phosphofructokinase activity in human breast cancer tissues is different from the one observed in control tissues and that this phenomenon may be involved in the increased glycolytic flux observed in those cells. Through co-sedimentation techniques, we observed that 60% of phosphofructokinase activity in neoplastic tissues is located in an actin-enriched fraction, against 36% in control tissues. Additionally, metastatic tumor tissues presented a two fold increase in this particulate activity when compared to non-metastatic tumor samples. We propose that the alteration in cellular distribution of phosphofructokinase activity in human breast cancer tissues is a mechanism associated to the process of cell transformation and may be a consequence of the altered hormonal milieu observed in several types of cancer. 相似文献
59.
Alen Hajnal Sergio Fonseca Jeffrey M. Kinsella-Shaw Paula Silva Claudia Carello M.T. Turvey 《Neuroscience letters》2007
Nonvisual perceptions of a wielded object's spatial properties are based on the quantities expressing the object's mass distribution, quantities that are invariant during the wielding. The mechanoreceptors underlying the kind of haptic perception involved in wielding – referred to as effortful, kinesthetic, or dynamic touch – are those embedded in the muscles, tendons, and ligaments. The present experiment's focus was the selectivity of this muscle-based form of haptic perception. For an occluded rod grasped by the hand at some intermediate position along its length, participants can attend to and report selectively the rod's full length, its partial lengths (fore or aft of the hand), and the position of the grip. The present experiment evaluated whether participants could similarly attend selectively when wielding by foot. For a given rod attached to and wielded by foot or attached to (i.e. grasped) and wielded by hand, participants reported (by magnitude production) the rod's whole length or fractional length leftward of the point of attachment. On measures of mean perceived length, accuracy, and reliability, the degree of differentiation of partial from full extent achieved by means of the foot matched that achieved by means of the hand. Despite their neural, anatomical, and experiential differences, the lower and upper limbs seem to abide by the same principles of selective muscle-based perception and seem to express this perceptual function with equal facility. 相似文献
60.
Dr. Peter J. Felsburg Richard L. Somberg Brian J. Hartnett Paula S. Henthorn Simon R. Carding 《Immunologic research》1998,17(1-2):63-73
Our laboratory has identified and characterized an X-linked severe combined immunodeficiency (XSCID) in dogs that is due to mutations in the common gamma (γc) subunit of the interleukin-2 (IL2), IL4, IL7, IL9, and IL 15 receptors. Canine XSCID, unlike genetically engineered γc-deficient mice, has a clinical and immunologic phenotype virtually identical to human XSCID. It appears that speciesspecific differences exist in the role of the γc and its associated cytokines in mice compared to their role in humans and dogs, suggesting γc-deficient dogs may be a more relevant model for studing the role of the γc in humans. We are utilizing this model for a variety of studies to address:
- Fundamental questions concerning the role of the γc in cytokine regulation and lymphocyte development.
- The pathogenesis of XSCID.
- Strategies for improving bone marrow transplantation outcome.
- Development and evaluation of strateies for gene therapy.
- Human hematopoietic stem cell development.