全文获取类型
收费全文 | 10028篇 |
免费 | 1069篇 |
国内免费 | 83篇 |
专业分类
耳鼻咽喉 | 59篇 |
儿科学 | 301篇 |
妇产科学 | 137篇 |
基础医学 | 1187篇 |
口腔科学 | 571篇 |
临床医学 | 1146篇 |
内科学 | 1828篇 |
皮肤病学 | 148篇 |
神经病学 | 688篇 |
特种医学 | 426篇 |
外科学 | 1064篇 |
综合类 | 409篇 |
一般理论 | 1篇 |
预防医学 | 1365篇 |
眼科学 | 278篇 |
药学 | 896篇 |
1篇 | |
中国医学 | 44篇 |
肿瘤学 | 631篇 |
出版年
2021年 | 125篇 |
2020年 | 82篇 |
2019年 | 133篇 |
2018年 | 150篇 |
2017年 | 133篇 |
2016年 | 156篇 |
2015年 | 187篇 |
2014年 | 233篇 |
2013年 | 343篇 |
2012年 | 379篇 |
2011年 | 469篇 |
2010年 | 321篇 |
2009年 | 267篇 |
2008年 | 344篇 |
2007年 | 398篇 |
2006年 | 389篇 |
2005年 | 426篇 |
2004年 | 465篇 |
2003年 | 425篇 |
2002年 | 476篇 |
2001年 | 448篇 |
2000年 | 377篇 |
1999年 | 335篇 |
1998年 | 241篇 |
1997年 | 257篇 |
1996年 | 166篇 |
1995年 | 139篇 |
1994年 | 132篇 |
1993年 | 151篇 |
1992年 | 195篇 |
1991年 | 196篇 |
1990年 | 236篇 |
1989年 | 219篇 |
1988年 | 177篇 |
1987年 | 191篇 |
1986年 | 173篇 |
1985年 | 147篇 |
1984年 | 126篇 |
1983年 | 116篇 |
1982年 | 80篇 |
1981年 | 64篇 |
1980年 | 53篇 |
1979年 | 88篇 |
1978年 | 73篇 |
1977年 | 64篇 |
1976年 | 68篇 |
1975年 | 55篇 |
1974年 | 61篇 |
1973年 | 67篇 |
1970年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
A comparison has been made of the in vitro light-activated drug cytotoxicities of two different porphyrin compounds, Photofrin II and TPPS4. An early passage human colon adenocarcinoma cell line, WiDr, has been exposed to either drug for 24 h, the excess drug washed from the cells and the cells irradiated with light using quartz-tungsten-halogen lamps. Neither light nor drug alone under the experimental conditions employed was toxic to WiDr cells. Together, considerable cytotoxicity could be seen and the shapes of the cell survival curves following exposure to either drug then irradiation with light, were similar. For equal amounts of drug in the medium, Photofrin II was a more efficient photosensitizer of WiDr cells than TPPS4, and differences in cellular uptake could only partly explain this. When the experimental procedure was changed by reducing the temperature of irradiation, a reduction in photosensitizing efficiency could be demonstrated. This was more pronounced for Photofrin II, and was seen as a change in the slope of the final portion of the survival curve; and as a change in the shoulder for TPPS4. Two different batches of the two drugs were compared and shown to give slightly different results for Photofrin II (change in shoulder) but not to differ for TPPS4. 相似文献
42.
Richard West 《Journal of medical ethics》1994,20(4):265-266
43.
pHo is an important determinant of vascular tone in cerebral blood vessels. We investigated the effects of changes in pHo on isolated smooth muscle cells from the basilar artery of the guinea pig. Single cells contracted rapidly in response to an elevation in pHo (constant CO2), and contraction was blocked by nifedipine, suggesting a role for dihydropyridine-sensitive Ca2+ channels. In whole-cell patch-clamp experiments, changes in pHo (pHo 5.7-8.1, pHi 7.2 with 10 mM HEPES) strongly affected the amplitude of the peak Ca2+ channel current (10 mM Ba2+, +15 mV, holding potential of -55 mV), with an apparent pK of 6.9. The current-voltage curves were minimally shifted, indicating no important effect of surface charge. To separate the slowly inactivating L-type Ca2+ channel current from the more rapidly inactivating B-type current, the decaying portions of inward currents from cells studied with repetitive 1-second pulses (+15 mV, holding potential of -55 mV) were fit to a two-component model. Titration curves for the L-type and B-type currents indicated maximum increases by factors of 3.65 and 1.28 at alkaline pHo and gave apparent pK values of 7.71 and 6.47 (Hill coefficient unity). The time constant of inactivation for the B-type current at +15 mV was little affected by pHo, whereas that for the L-type current increased somewhat with increasing pHo. Additional experiments showed no significant effect of pHo on holding current or on voltage-activated outward currents (pCai 7 with 11 mM EGTA). Our results provide additional evidence for participation of Ca2+ channels in regulating basal tone in cerebral smooth muscle and indicate that pHo regulates current through slowly inactivating, dihydropyridine-sensitive L-type Ca2+ channels. 相似文献
44.
Stacey M Pollock-Barziv Anne I Dipchand Brian W McCrindle Nadya Nalli Lori J West 《The Journal of heart and lung transplantation》2005,24(2):190-194
BACKGROUND: While Tacrolimus (Tac) and Cyclosporine (Cya) immunosuppression are used after cardiac transplantation (tx), few studies have evaluated their use in pediatric patients. METHODS: We randomized 26 heart transplant recipients (pts) in a prospective, open-label trial to Tac (n = 14) or Cya (n = 12) to compare their efficacy and side-effects. Mean age at tx was 4.2 years for Tac and 5.8 years for Cya. Mean follow-up was 26 months (range: 11-39 months) for Tac and 24 months for Cya (range: 33-13 months). RESULTS: Our data suggest that both regimens are efficacious in the pediatric population. Conversion from Cya to Tac was useful for dealing with persistent rejection, although this sample did not suggest lower incidence of acute cellular rejection in the Tac group. CONCLUSIONS: Further studies are required to establish pharmacokinetic parameters to enhance therapeutic monitoring of these patients to minimize side effects and enhance outcomes. 相似文献
45.
The characterization and pathological significance of gastric Campylobacter-like organisms in the ferret: a model for chronic gastritis? 总被引:6,自引:0,他引:6
Gastric campylobacter-like organisms (CLO) were isolated from gastric tissues removed at sacrifice from 17 mature ferrets; all animals were colonized, but no macroscopic mucosal lesions or histological features of chronic gastritis were seen. The isolates resembled Campylobacter pylori in many cultural and biochemical characteristics, and produced substantial urease activity, but there were sufficient differences from C. pylori to suggest that ferret gastric CLO represents a separate species. Comparison of human C. pylori and ferret gastric CLO may help to elucidate the pathogenicity of the former in patients with gastritis, and the ferret may serve as a useful animal model for the study of C. pylori infection. 相似文献
46.
Intestinal schistosomiasis japonica: CT-pathologic correlation 总被引:1,自引:0,他引:1
Lee RC; Chiang JH; Chou YH; Rubesin SE; Wu HP; Jeng WC; Hsu CC; Tiu CM; Chang T 《Radiology》1994,193(2):539
47.
48.
The effects of amphetamine on the extinction of intracranial self-stimulation (ICSS) and on postextinction ICSS performance were examined in rats implanted with electrodes either in medial prefrontal cortex (mPFC) or in the posterior hypothalamus-ventral tegmental area (PH-VTA). Lever-pressing for ICSS was allowed to stabilize in daily 15-minute sessions before each animal was exposed to 5 minutes of extinction (responding without reward). Animals were administered either 0.25 mg/kg d-amphetamine or saline before baseline, extinction and postextinction sessions. After amphetamine treatment, the number of lever presses during extinction was higher in mPFC animals and lower in PH-VTA animals compared with saline-treated controls. Rates did not change immediately after extinction but, one day later, rates had increased in all saline-treated animals (both PH-VTA and mPFC animals) and had decreased in all amphetamine-treated animals. These findings demonstrated that the effects of amphetamine on the extinction of ICSS were different in cortical and hypothalamic sites, possibly because of regional differences in stimulus-evoked reinforcement and inhibitory processes. 相似文献
49.
D. Bakish C. L. Hooper D. L. West C. Miller A. Blanchard F. Bashir 《Human psychopharmacology》1995,10(2):105-109
This retrospective study was undertaken with the objective of determining how effective and safe moclobemide, a specific and reversible inhibitor of monoamine oxidase-A (RIMA), is when used in combination with specific serotonin re-uptake inhibitors (SSRIs), in a clinical setting. A thorough chart review was done of all patients with affective and anxiety disorders seen at our centre who received combination treatment with moclobemide and an SSRI. Combination moclobemide-SSRI treatment demonstrated good efficacy in treating treatment-resistant patients. The combination treatment was well tolerated with very few drug interactions. Dosages should be started low, titrated slowly and carefully, and patients should be monitored closely. 相似文献
50.
The role of intestinal flora on the interactions between nonparenchymal cells and hepatocytes in coculture 总被引:2,自引:0,他引:2
T R Billiar M A Maddaus M A West D L Dunn R L Simmons 《The Journal of surgical research》1988,44(4):397-403
Kupffer cells are exposed directly to a number of factors in the portal circulation that can modify or regulate their responses to septic stimuli. The gut represents a potential source of a number of these factors including endotoxin, lymphokines, and prostaglandins. We examined Kupffer cells from germfree rats and germfree rats exposed to endotoxin or bacteria via their GI tracts to determine the importance of the intestinal flora in maintaining or modulating Kupffer cell responses. Kupffer cells from germfree animals were reduced in numbers and failed to respond to LPS in Kupffer cell: hepatocyte coculture. When germfree rats were exposed to bacterial endotoxin or bacteria via the gastrointestinal tract their Kupffer cells increased in numbers to normal and the cells responded to LPS in culture. Intestinal overgrowth with Escherichia coli for 2 days activated the Kupffer cells and significantly increased Kupffer cell sensitivity to LPS. These data suggest that the environment of the gastrointestinal tract is important for normal Kupffer cell responses and that intestinal bacterial overgrowth can modify Kupffer cell responses to septic stimuli. 相似文献