全文获取类型
收费全文 | 2759篇 |
免费 | 178篇 |
国内免费 | 33篇 |
专业分类
耳鼻咽喉 | 28篇 |
儿科学 | 66篇 |
妇产科学 | 65篇 |
基础医学 | 403篇 |
口腔科学 | 20篇 |
临床医学 | 195篇 |
内科学 | 735篇 |
皮肤病学 | 73篇 |
神经病学 | 344篇 |
特种医学 | 93篇 |
外科学 | 266篇 |
综合类 | 6篇 |
预防医学 | 127篇 |
眼科学 | 14篇 |
药学 | 234篇 |
中国医学 | 4篇 |
肿瘤学 | 297篇 |
出版年
2024年 | 7篇 |
2023年 | 33篇 |
2022年 | 80篇 |
2021年 | 131篇 |
2020年 | 92篇 |
2019年 | 87篇 |
2018年 | 119篇 |
2017年 | 74篇 |
2016年 | 111篇 |
2015年 | 107篇 |
2014年 | 155篇 |
2013年 | 170篇 |
2012年 | 219篇 |
2011年 | 228篇 |
2010年 | 132篇 |
2009年 | 132篇 |
2008年 | 179篇 |
2007年 | 196篇 |
2006年 | 180篇 |
2005年 | 118篇 |
2004年 | 120篇 |
2003年 | 89篇 |
2002年 | 80篇 |
2001年 | 20篇 |
2000年 | 15篇 |
1999年 | 15篇 |
1998年 | 7篇 |
1997年 | 9篇 |
1995年 | 4篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有2970条查询结果,搜索用时 0 毫秒
1.
2.
Alessia Pascale Marialaura Amadio Stefano Govoni Fiorenzo Battaini 《Pharmacological research》2007,55(6):560-569
The brain represents the primary centre for the regulation and control of all our body activities, receiving and interpreting sensory impulses and transmitting information to the periphery. Most importantly, it is also the seat of consciousness, thought, emotion and especially memory, being in fact able to encode, store and recall any information. Memory is really what makes possible so many of our complex cognitive functions, including communication and learning, and surely without memory, life would lose all of its glamour and purpose. Age-associated mental impairment can range in severity from forgetfulness at the border with pathology to dementia, such as in Alzheimer's disease. In recent years, one of the most relevant observations of research on brain aging relates to data indicating that age-related cognitive decline is not only due to neuronal loss, as previously thought; instead, scientists now believe that age-associated functional changes have more to do with the dysfunctions occurring over time. Within this context a prominent role is certainly played by signal transduction cascades which guarantee neuronal cell to elaborate coordinated responses to the multiple signals coming from the outside and to adapt itself to the environmental changes and requests. This review will focus the attention on protein kinase C pathway, with a particular interest on its activation process, and on the role of protein-lipid and protein-protein interactions to selectively localize the cellular responses. Furthermore, information is emerging and will be discussed on the possibility of mRNA stabilization through PKC activation. This review will also approach the issue on how alterations of these molecular cascades may have implications in physiological and pathological brain aging, such as Alzheimer's disease. 相似文献
3.
Rebecca Voltan Arianna Castaldello Egidio Brocca-Cofano Rita De Michele Chiara Triulzi Giuseppe Altavilla Luisa Tondelli Michele Laus Katia Sparnacci Eva Reali Riccardo Gavioli Barbara Ensoli Antonella Caputo 《Vaccine》2009
Cationic block copolymers spontaneously assemble via electrostatic interactions with DNA molecules in aqueous solution giving rise to micellar structures that protect the DNA from enzymatic degradation both in vitro and in vivo. In addition, we have previously shown that they are safe, not immunogenic and greatly increased antigen-specific CTL responses following six intramuscular inoculations of a very low dose (1 μg) of the vaccine DNA as compared to naked DNA. Nevertheless, they failed to elicit detectable humoral responses against the antigen. To gain further insight in the potential application of this technology, here we show that a shorter immunization protocol based on two DNA intramuscular inoculations of 1 μg of DNA delivered by these copolymers and a protein boost elicits in mice broad (both humoral and cellular) and long-lasting responses and increases the antigen-specific Th1-type T cell responses and CTLs as compared to priming with naked DNA. These results indicate that cationic block copolymers represent a promising adjuvant and delivery technology for DNA vaccination strategies aimed at combating intracellular pathogens. 相似文献
4.
Eugenia Cordelli Anna Maria Fresegna Alessia D'Alessio Patrizia Eleuteri Marcello Spanò Francesca Pacchierotti Paola Villani 《Toxicological sciences》2007,99(2):545-552
The increasing request of chemical safety assessment demands for the validation of alternative methods to reduce the resort to animal experimentation. Methods that evaluate reproductive toxicity are among those requiring the largest use of animals. Presently, no validated in vitro alternative exists for the assessment of reproductive toxicity. Mammalian sperm are sensitive targets of DNA-reactive chemicals, which form premutagenic adducts. Here, we propose a new method based on comet assay to detect DNA damage induced by potential germ cell mutagens in bull sperm available from assisted reproduction practices. In somatic cells, chemical-induced adducts can be revealed by comet assay that detects DNA breaks produced during adduct repair. Mature sperm, however, are devoid of repair enzymes, and adducts are processed only after fertilization. For this reason, comet assay is not sensitive to detect DNA lesions induced in sperm by most chemicals. To overcome such limitation, we developed a modified comet assay based on the addition of a protein extract from HeLa cells to agarose-embedded sperm on microscopic slides. To test the method, sperm were treated in vitro with methyl methanesulfonate (MMS) or melphalan (MLP) and comet assay was conducted both with and without protein supplementation. No effect of MMS or MLP was detected without protein supplementation; on the contrary, a clear-cut dose-dependent effect was measured after addition of the cell extract. These results represent a proof of concept of a novel in vitro mutagenicity test on sperm that could offer a promising approach to complement previously validated in vivo germ cell genotoxicity assays. 相似文献
5.
Giuseppe Derosa Arrigo F G Cicero Angela D'Angelo Pietro D Ragonesi Leonardina Ciccarelli Mario N Piccinni Fabio Pricolo Sibilla A T Salvadeo Ilaria Ferrari Alessia Gravina Roberto Fogari 《Hypertension research》2006,29(11):849-856
The aim of our study was to investigate the metabolic effect of telmisartan and irbesartan in subjects treated with rosiglitazone, a well-known insulin-sensitizing drug, in order to clarify the direct metabolic effects of the two former drugs. Patients were enrolled, evaluated, and followed at 3 Italian centers. We evaluated 188 type 2 diabetic patients with metabolic syndrome (94 males and 94 females in total; 49 males and 46 females, aged 56+/-5, treated with telmisartan; and 45 males and 48 females, aged 55+/-4, treated with irbesartan). All had been diabetic for at least 6 months, and glycemic control by the maximum tolerated dietary changes and maximum tolerated dose of oral hypoglycemic agents had been attempted and failed in all cases. All patients took a fixed dose of rosiglitazone, 4 mg/day. We administered telmisartan (40 mg/day) or irbesartan (150 mg/day) in a randomized, controlled, double-blind clinical manner. We evaluated body mass index (BMI), glycemic control (HbA1c fasting plasma glucose and insulin levels [FPG, and FPI, respectively], and homeostasis model assessment [HOMA] index), lipid profile (total cholesterol [TC], low density lipoprotein-cholesterol [LDL-C], high density lipoprotein-cholesterol [HDL-C], and triglycerides [TG]), systolic and diastolic blood pressure (SBP and DBP), tumor necrosis factor-alpha (TNF-alpha), and leptin during the 12 months of this treatment. No BMI change was observed after 6 or 12 months in either group. Significant decreases in HbAlc and FPG were observed after 6 months in the telmisartan group, and after 12 months in both groups. The decrease in HbA1c and FPG at 12 months was statistically significant only in the telmisartan group. A significant decrease in FPI was observed at 12 months in both groups, and this decrease was significantly greater in the telmisartan group. Significant decreases in the HOMA index were observed at 6 and 12 months in both groups, and the decrease in the HOMA index after 12 months was significantly greater in the telmisartan group than in the irbesartan group. Significant changes in SBP, DBP, TC, and LDL-C were observed after 6 and 12 months in both groups. Significant decreases in TNF-alpha and leptin levels were observed after 6 months in the telmisartan group, and after 12 months in both groups. In conclusion, in this study of patients with type 2 diabetes mellitus and metabolic syndrome, telmisartan seemed to result in a greater improvement in glycemic and lipid control and metabolic parameters related to metabolic syndrome compared to irbesartan. These observed metabolic effects of different angiotensin type 1 receptor blockers could be relevant when choosing a therapy to correct metabolic derangement of patients affected by metabolic syndrome and diabetes. 相似文献
6.
7.
8.
Alessia Bacchi Mauro Carcelli Giancarlo Pelizzi Paola Vicini 《Archiv der Pharmazie》1995,328(3):217-221
The amino/imino equilibrium is studied in free bases and hydrochloride salts of amidinobenzisothiazole derivatives by IR and 1H-NMR spectroscopy. The X-ray crystallographic analysis of two of these compounds shows that the free base exists as amino form whereas the hydrochloride as imino form. 相似文献
9.
Vasculogenic mimicry has no prognostic significance in pT3 and pT4 cutaneous melanoma 总被引:4,自引:0,他引:4
Massi D Franchi A Paglierani M Ketabchi S Borgognoni L Reali UM Santucci M 《Human pathology》2004,35(4):496-502
The concept of vasculogenic mimicry has been introduced to define periodic acid-Schiff (PAS)-positive channels and loops lined by tumor cells, instead of endothelium, able to contribute to microcirculation in uveal melanomas. Previous studies have shown that the PAS-positive patterns are associated with a poor prognosis in uveal melanoma. The aim of the current study was to investigate whether vasculogenic mimicry has a prognostic impact in pT3 and pT4 cutaneous melanoma. Fifteen patients with pT3 and pT4 cutaneous melanoma who did not experience progression after 10 years of follow-up and 30 matched controls who underwent progression were selected. Tumor sections were stained with PAS reaction, omitting the nuclear counterstaining. For immunohistochemistry, sections were stained with CD31, CD105 (endoglin), and laminin. Differences in the distribution of the PAS-positive patterns and a series of clinicopathological variables were evaluated by the Pearson chi(2) and Mann-Whitney U tests. We observed PAS-positive linear sheets, arcs, elliptical loops, and networks encircling roundish to oval aggregates of melanoma cells. The overall distribution of the PAS-positive patterns did not match with the blood microvessels' architecture as detected by immunohistochemical analysis. No statistically significant differences in the distribution of PAS-positive patterns were found between cases and controls. The presence of a parallel pattern correlated significantly with thickness (P = 0.04), whereas an inverse correlation was found with vessel area (P = 0.05). In conclusion, our results suggest that there is a mismatch between vasculogenic mimicry and tumor angiogenesis and do not support any prognostic role of vasculogenic mimicry in thick cutaneous melanoma. 相似文献
10.