全文获取类型
收费全文 | 2906篇 |
免费 | 154篇 |
国内免费 | 21篇 |
专业分类
耳鼻咽喉 | 11篇 |
儿科学 | 47篇 |
妇产科学 | 109篇 |
基础医学 | 366篇 |
口腔科学 | 17篇 |
临床医学 | 336篇 |
内科学 | 718篇 |
皮肤病学 | 74篇 |
神经病学 | 274篇 |
特种医学 | 100篇 |
外科学 | 320篇 |
综合类 | 10篇 |
一般理论 | 2篇 |
预防医学 | 210篇 |
眼科学 | 27篇 |
药学 | 198篇 |
中国医学 | 5篇 |
肿瘤学 | 257篇 |
出版年
2023年 | 22篇 |
2022年 | 65篇 |
2021年 | 71篇 |
2020年 | 32篇 |
2019年 | 50篇 |
2018年 | 82篇 |
2017年 | 59篇 |
2016年 | 63篇 |
2015年 | 83篇 |
2014年 | 98篇 |
2013年 | 143篇 |
2012年 | 207篇 |
2011年 | 210篇 |
2010年 | 113篇 |
2009年 | 109篇 |
2008年 | 190篇 |
2007年 | 193篇 |
2006年 | 180篇 |
2005年 | 149篇 |
2004年 | 154篇 |
2003年 | 133篇 |
2002年 | 121篇 |
2001年 | 48篇 |
2000年 | 35篇 |
1999年 | 53篇 |
1998年 | 19篇 |
1997年 | 18篇 |
1996年 | 21篇 |
1995年 | 19篇 |
1994年 | 17篇 |
1993年 | 15篇 |
1992年 | 36篇 |
1991年 | 26篇 |
1990年 | 29篇 |
1989年 | 27篇 |
1988年 | 23篇 |
1987年 | 25篇 |
1986年 | 27篇 |
1985年 | 21篇 |
1984年 | 12篇 |
1983年 | 5篇 |
1982年 | 12篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1974年 | 6篇 |
1945年 | 9篇 |
1943年 | 4篇 |
排序方式: 共有3081条查询结果,搜索用时 421 毫秒
991.
992.
Íngara Keisle São Paulo Barretto Miranda Anderson Fontes Suzart Miranda Fernanda Vidigal Duarte Souza Marcos André Vannier-Santos Carlos Priminho Pirovani Iuri Muniz Pepe 《International journal of food sciences and nutrition》2017,68(4):442-454
The current study aims to extract bromelain from different parts (stem, crown, peels, pulp and leaves) of Ananas comosus var. comosus AGB 772; to determine of optimum pH and temperature; to test bromelain stability in disodium EDTA and sodium benzoate, and to investigate its pharmacological activity on B16F10 murine melanoma cells in vitro. The highest enzymatic activity was found in bromelain extracted from the pulp and peel. The optimum bromelain pH among all studied pineapple parts was 6.0. The optimum temperature was above 50?°C in all bromelain extracts. The fluorescence analysis confirmed the stability of bromelain in the presence of EDTA and sodium benzoate. Bromelain was pharmacologically active against B16F10 melanoma cells and it was possible verifying approximately 100% inhibition of tumor cell proliferation in vitro. Since bromelain activity was found in different parts of pineapple plants, pineapple residues from the food industry may be used for bromelain extraction. 相似文献
993.
994.
Patrizia Mondello Cristian Di Mirto Salvatore Cuzzocrea Carmela Arrigo Michael Mian Vincenzo Pitini 《Clinical Lymphoma, Myeloma & Leukemia》2019,19(8):e489-e495
BackgroundDespite the important progress in the research of myeloproliferative neoplasms (MPN), treatment options are still limited. Currently, a cytoreductive approach is the backbone treatment, with hydroxyurea (HU) being the most important agent. However, this drug is not always well-tolerated and has been questionably linked to a potential leukemogenic effect. A valid alternative is interferon alfa (IFN-α), but it is reserved for selected patients owing to the more frequent side effects and the lack of final results from the studies directly comparing IFN-α with HU, which is why we provided the results of the so far largest real-life analysis.Patients and MethodsFrom 2000 to 2016, 63 patients with Philadelphia-negative MPN prospectively received either HU or IFN-α.ResultsDuring a median follow-up period of 121 months (range, 88-168 months), 97% of the patients treated with IFN-α achieved a hematologic response (60% complete, 37% partial) compared with 78% in the HU group (56% complete, 20% partial; P < .01). Molecular responses were limited to patients treated with IFN-α. IFN-α was well-tolerated with no secondary malignancy, whereas HU was associated with more toxic events and cases of leukemic transformation. A significantly longer progression-free survival (5.0 vs. 3.1 years; P < .001) and overall survival (7.8 vs. 5.8 years; P = .006) were observed in the IFN-α group compared with the HU cohort.ConclusionOur data support IFN-α as a more valid therapeutic option owing to its more profound hematologic responses, durable molecular remissions, long-term disease control, and reduced risk of leukemic transformation with a favorable toxicity profile. 相似文献
995.
996.
Daniela Melchiorre Elisa Pratelli Elena Torricelli Francesco Sofi Rosanna Abbate Marco Matucci-Cerinic GianFranco Gensini Guglielmina Pepe 《Internal and emergency medicine》2016,11(5):703-711
The involvement of the musculoskeletal system with other mild pleiotropic manifestations represents a clinical criterion, called “systemic features,” to diagnose Marfan’s syndrome. We aimed to investigate the features of the hands and feet redressable contractures present in a group of Marfan patients. In 13 patients with previously diagnosed Marfan’s syndrome, an accurate clinical examination was performed. In particular the characterization of the musculoskeletal system by visual analogic scale to measure muscle pain (VAS) and muscle strength (MRC system) was carried out; the Beighton scale score was used to evaluate the articular hypermobility. Ultrasound examination (US) was performed to detect deep-superficial flexor tendons and extensor tendons of both hands, and the short and long flexor and extensor tendons of the fingers and toes in static and dynamic positions. The ImageJ program was adopted to measure a profile of tendon echo-intensity. A reduction of the thickness of all tendons was detected by US in our patients; the VAS and Beighton scale scores were in normal ranges. The profile of tendon echo-intensity showed different textural details in all Marfan patients. This study provides evidence for other contractures’ localization, and for altered findings of the tendons in patients with Marfan syndrome and finger/toe contractures. These changes may be associated with structural modifications in connective tissue. 相似文献
997.
We determined whether the reduction in placental progesterone (P4) production observed after administration of the antiestrogen ethamoxytriphetol (MER-25) to pregnant baboons was associated with a decline in activity and/or content of the placental mitochondrial cholesterol side-chain cleavage system (P-450scc). Pregnant baboons (Papio anubis) were untreated (n = 9) or administered MER-25 (25 mg/kg BW, orally; n = 6) daily on days 140-170 of gestation (term = 184 days). Placentas were obtained by cesarean section on day 170 of gestation, and P-450scc activity and cytochrome P-450 content were determined on mitochondria-rich fractions. Administration of MER-25 to pregnant baboons resulted in a 40% reduction (P less than 0.01, by Student's t test) in the mean (+/- SE) peripheral serum P4 concentration (6.3 +/- 0.3 ng/ml) compared to that in untreated (10.4 +/- 0.3 ng/ml) baboons. P-450scc activity, as determined by formation of pregnenolone (P5) and P4 during a 30-min incubation (picomoles per mg protein), was 37% lower (P less than 0.01) in placental mitochondria obtained from MER-25-treated baboons (179.8 +/- 25.0) than in that from untreated (285.4 +/- 13.4) baboons. Mitochondrial cytochrome P-450 content, assessed by spectral analysis, was 28% lower (P less than 0.02) in antiestrogen-treated (46.7 +/- 2.1 pmol/mg protein) than in untreated (64.8 +/- 5.2 pmol/mg protein) baboons. The initial (time zero) free cholesterol content (nanomoles per mg protein) of mitochondrial-rich preparations was not significantly different in antiestrogen-treated (189.3 +/- 13.0) and untreated (225.0 +/- 15.1) animals. Collectively, these results suggest that the decline in placental P4 production observed in baboons in response to MER-25 occurs at least in part as a result of a decrease in cytochrome P-450scc activity. The loss in P-450scc activity appears to be an intramitochondrial event and not a result of depletion of the total mitochondrial cholesterol pool. We propose, therefore, that one mechanism by which estrogen may regulate the production of P4 by the placenta during primate pregnancy is via the maintenance of placental mitochondrial cytochrome P-450, the terminal oxidase of cytochrome P-450scc. 相似文献
998.
Brunetti ND Pepe M Munno I Tiecco F Quagliara D De Gennaro L Gaglione A Di Biase M Favale S 《Coronary artery disease》2008,19(3):133-137
AIM: The aim of this study is to investigate the T helper (Th)2-dependent release of interleukin(IL)-4 and IL-13 in patients with unstable angina treated with coronary angioplasty (PCI). METHODS: This study involved 48 consecutive patients with unstable angina who underwent PCI. Blood samples were taken before and 48 h after PCI to evaluate serum IL-4 and IL-13 levels. Coronary atherosclerosis was assessed in terms of the severity of the treated lesions and the presence of multivessel disease, and compared with IL release. RESULTS: Before and after PCI, serum IL-4 levels were, respectively, 53.1+/-110.7 and 35.1+/-16.9 pg/ml (P not significant), and serum IL-13 levels 6.7+/-3.7 and 6.0+/-2.9 pg/ml (P<0.05). A correlation was present between the severity of the treated coronary lesions and serum IL-13 levels (r 0.36; P<0.05). The patients with multivessel coronary artery disease had a higher periprocedure ratio of IL-4 than those with single-vessel coronary artery disease (1.46+/-0.76 vs. 0.89+/-0.34, P<0.001). CONCLUSION: A significant decrease was observed in Th2-dependent IL concentrations after PCI; increased Th2-dependent IL levels before PCI seem to correlate with the severity of coronary atherosclerosis. 相似文献
999.
Regulation of placental vascular endothelial growth/permeability factor expression and angiogenesis by estrogen during early baboon pregnancy 总被引:3,自引:0,他引:3
Albrecht ED Robb VA Pepe GJ 《The Journal of clinical endocrinology and metabolism》2004,89(11):5803-5809
We have recently shown that there was a developmental increase in placental trophoblast vascular endothelial growth/permeability factor (VEG/PF) expression and vascularization that closely paralleled maternal serum estrogen levels during advancing baboon gestation. The present study determined whether estrogen regulates these important aspects of primate development. VEG/PF mRNA levels were determined by competitive RT-PCR in isolated villous placental cells, and placental vascularization was assessed by image analysis. Placentas were obtained on d 60 of gestation (length of gestation is 184 d) from baboons in which estrogen levels on d 25-59 were increased by daily administration of aromatizable androstenedione or decreased by aromatase inhibitor CGS 20267. Androstenedione treatment increased maternal serum estradiol levels 3-fold (P < 0.01) and placental villous cytotrophoblast VEG/PF mRNA level to a value (mean +/- se, 26,836 +/- 5,625 attomoles/microg total RNA) 2.5-fold greater (P < 0.05) than that in untreated animals (11,645 +/- 1,746 attomoles/microg RNA). In contrast, administration of CGS 20267 decreased serum estradiol (P < 0.01) and placental cytotrophoblast mRNA (2,912 +/- 693 attomoles/microg RNA; P < 0.05) levels by 75%, effects prevented by concomitant administration of CGS 20267 and estradiol. VEG/PF mRNA levels in inner villous cells were unaltered. Coinciding with the increase in placental VEG/PF expression, the percent vascularized area (3.46 +/- 0.23) and vessel density (493 +/- 34 vessels/mm(2)) of the villous placenta in untreated baboons on d 60 were increased (P < 0.01) in baboons in which estrogen levels were elevated by androstenedione treatment (6.54 +/- 0.56 and 743 +/- 27 vessels/mm(2), respectively). It is concluded that estrogen has an important role in stimulating trophoblast VEG/PF expression and consequently villous placental angiogenesis to promote fetal growth and development in early primate pregnancy. 相似文献
1000.