全文获取类型
收费全文 | 1800篇 |
免费 | 102篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 151篇 |
妇产科学 | 17篇 |
基础医学 | 194篇 |
口腔科学 | 47篇 |
临床医学 | 171篇 |
内科学 | 387篇 |
皮肤病学 | 23篇 |
神经病学 | 96篇 |
特种医学 | 471篇 |
外科学 | 132篇 |
综合类 | 28篇 |
预防医学 | 43篇 |
眼科学 | 14篇 |
药学 | 74篇 |
中国医学 | 3篇 |
肿瘤学 | 72篇 |
出版年
2022年 | 4篇 |
2021年 | 11篇 |
2020年 | 12篇 |
2019年 | 7篇 |
2018年 | 17篇 |
2017年 | 10篇 |
2016年 | 27篇 |
2015年 | 31篇 |
2014年 | 30篇 |
2013年 | 60篇 |
2012年 | 35篇 |
2011年 | 32篇 |
2010年 | 78篇 |
2009年 | 64篇 |
2008年 | 38篇 |
2007年 | 38篇 |
2006年 | 39篇 |
2005年 | 25篇 |
2004年 | 22篇 |
2003年 | 22篇 |
2002年 | 32篇 |
2001年 | 21篇 |
2000年 | 30篇 |
1999年 | 37篇 |
1998年 | 134篇 |
1997年 | 121篇 |
1996年 | 124篇 |
1995年 | 92篇 |
1994年 | 74篇 |
1993年 | 82篇 |
1992年 | 24篇 |
1991年 | 24篇 |
1990年 | 18篇 |
1989年 | 63篇 |
1988年 | 47篇 |
1987年 | 51篇 |
1986年 | 45篇 |
1985年 | 52篇 |
1984年 | 28篇 |
1983年 | 33篇 |
1982年 | 35篇 |
1981年 | 20篇 |
1980年 | 36篇 |
1979年 | 14篇 |
1978年 | 15篇 |
1977年 | 17篇 |
1976年 | 23篇 |
1975年 | 24篇 |
1971年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有1924条查询结果,搜索用时 15 毫秒
1.
2.
3.
G P Tuszynski M Smith V L Rothman D M Capuzzi R R Joseph J Katz E C Besa J Treat H I Switalska 《Thrombosis and haemostasis》1992,67(6):607-611
Thrombospondin (TSP), a large glycoprotein present in platelets, and various normal and tumor tissues, has recently been shown to promote cell adhesion and platelet aggregation. Most importantly because TSP has been shown to promote metastasis of melanoma tumor cells to the lung in a murine model (1) and since thromboembolic events commonly occur in patients afflicted with metastatic tumors, we explored the role of TSP in human cancer by measuring TSP blood levels in patients with various malignant neoplasms. Blood TSP levels were measured by indirect enzyme-linked immunoadsorbent assay (ELISA) from 20 control subjects, 22 patients with gastrointestinal (GI) cancer, 18 patients with breast cancer, and 17 patients with lung cancer. Control subjects consisted both of healthy subjects and acutely ill patients with no malignancies. TSP levels of both healthy and acutely ill controls were found to range between 245-440 ng/ml with a mean of 365 ng/ml. In contrast, elevated levels of TSP greater than the mean value of 400 ng/ml for controls ranging between 590-3,650 ng/ml were found in 20/22 (91%) patients with GI malignancies, 13/18 (72%) patients with breast cancer, and 15/17 (88%) with lung cancer. Mean TSP levels of GI, breast, and lung cancer patients were 3, 2, and 3 fold greater than controls, respectively. Increased blood TSP levels in patients were not due to increased levels of platelets since both control and patient groups had platelet counts within the normal range. These results suggest that TSP may play a role in tumor cell metastasis in man and could serve as a blood marker for metastasis. 相似文献
4.
E D Cottrell J R Kappa N Stenach C A Fisher G P Tuszynski H I Switalska V P Addonizio 《The Journal of thoracic and cardiovascular surgery》1988,96(4):535-541
Contact between blood and artificial surfaces results in extensive quantitative and qualitative alterations in platelet function. We evaluated the efficacy of a brief infusion of iloprost (ZK36374), a stable analog of prostacyclin, in preventing these platelet changes during extracorporeal membrane oxygenation. Twelve nonsplenectomized male mongrel dogs (23 to 30 kg) were randomized to treatment (n = 6) and control (n = 6) groups. The treatment animals received an infusion of iloprost at a rate of 150 ng/kg/min with the infusion being terminated 30 minutes after the initiation of extracorporeal membrane oxygenation, despite the fact that all animals were maintained on extracorporeal membrane oxygenation for 3 hours. In the control group, platelet counts dropped to 54% +/- 8.9% (mean +/- standard error of the mean) of initial levels at 30 minutes of extracorporeal membrane oxygenation and gradually rose to 87.2% +/- 6.7% at 3 hours. In contrast, the platelet counts of the iloprost-treated dogs remained stable throughout extracorporeal membrane oxygenation at 98.3% +/- 4.2% of initial counts. Platelet reactivity toward adenosine diphosphate revealed a significant and permanent loss of platelet function in the control group (37.0% +/- 2.1% inhibition). In contrast, the iloprost group demonstrated significant inhibition of platelet reactivity (79.2% +/- 8.3%) during the iloprost infusion but a return to normal function (4.2% +/- 6.7% inhibition) after cessation of drug infusion which persisted throughout extracorporeal membrane oxygenation. Plasma levels of the platelet-specific protein thrombospondin rose progressively from 918 +/- 89 ng/ml to 1465 +/- 239 ng/ml (delta 548 +/- 179 ng/ml) at 30 minutes of extracorporeal membrane oxygenation, which indicates extensive release of platelet granule contents (p less than 0.05). In contrast, plasma thrombospondin levels in the iloprost group demonstrated no additional rise after cessation of the iloprost infusion. In conclusion, iloprost effectively preserves platelet number and function during extracorporeal circulation. The fact that its salutary effects outlast its presence in plasma suggests that prevention of initial platelet-synthetic surface interactions permits the appearance of reduced surface affinity for platelets and, thus, reduced synthetic surface thrombogenicity. 相似文献
5.
6.
Christopher D Herzog Biplob Dass James E Holden James Stansell Mehdi Gasmi Mark H Tuszynski Raymond T Bartus Jeffrey H Kordower 《Movement disorders》2007,22(8):1124-1132
Neurturin (NTN) is a potent survival factor for midbrain dopaminergic neurons. CERE-120, an adeno-associated virus type 2 (AAV2) vector encoding human NTN (AAV2-NTN), is currently being developed as a potential therapy for Parkinson's disease. This study examined the bioactivity and safety/tolerability of AAV2-NTN in the aged monkey model of nigrostriatal dopamine insufficiency. Aged rhesus monkeys received unilateral injections of AAV2-NTN into the caudate and putamen, with each animal therefore serving as its own control. Robust expression of NTN within the nigrostriatal system was observed 8 months postadministration. (18)F-fluorodopa imaging using positron emission tomography revealed statistically significant increases in (18)F-fluorodopa uptake in the injected striatum compared with the uninjected side at 4 and 8 months. In addition, at 8 months postadministration, a significant enhancement in tyrosine hydroxylase immunoreactive fibers and an increase in the number of tyrosine hydroxylase immunoreactive cells was observed in the AAV2-NTN injected striatum compared with the uninjected side. Robust activation of phosphorylated extracellular signal-regulated kinase immunoreactivity in the substantia nigra was also observed. Histopathological analyses revealed no adverse effects of AAV2-NTN in the brain. Collectively, these results are consistent with the neurotrophic effects of NTN on the dopaminergic nigrostriatal system and extend the growing body of evidence supporting the concept that AAV2-NTN may have therapeutic benefit for Parkinson's disease. 相似文献
7.
We report an adult female with a rare giant choledochal cyst. The patient presented following a normal pregnancy with the classical triad of an abdominal mass associated with jaundice and right upper quadrant abdominal pain. The cyst was excised using an intramural technique and biliary reconstruction achieved with a Roux-en-Y hepaticojejunostomy. Our patient has remained well with no evidence of malignancy over a 12 year review period. The aetiology and current management of this condition are discussed. 相似文献
8.
9.
Na+ dependence of in vitro pancreatic amylase release 总被引:1,自引:0,他引:1
10.
Determination of optimal cryoprotectants and procedures for their addition and removal from human spermatozoa 总被引:9,自引:7,他引:9
The objective was to test the hypothesis that the optimal cryoprotective
agent for cryopreservation of human spermatozoa would be a solute for which
cells have the highest plasma membrane permeability, resulting in the least
amount of volume excursion during its addition and removal. To test this
hypothesis, theoretical simulations were performed using membrane
permeability coefficients to predict optimal procedures for the addition
and removal of a cryoprotectant. Simulations were performed using data from
four different cryoprotectants: (i) glycerol, (ii) dimethyl sulphoxide,
(iii) propylene glycol and (iv) ethylene glycol. Thermodynamic formulations
were applied to determine approaches for the addition and removal of 1 M
and 2 M final concentrations of cryoprotectant, allowing the spermatozoa to
maintain a cell volume within their osmotic tolerance limits. Based on
these data, ethylene glycol was predicted to be optimal for minimizing
volume excursions among the solutes evaluated. These predictions were then
experimentally tested using glycerol as the control cryoprotectant and
ethylene glycol as the experimental cryoprotectant. The results indicate
that there was a higher (P < 0.05) recovery of motile spermatozoa after
cryopreservation when using 1 M ethylene glycol than with 1 M glycerol,
supporting the hypothesis that use of the cryoprotectant for which the cell
has the highest permeability will result in higher cell survival.
相似文献