全文获取类型
收费全文 | 11878篇 |
免费 | 1201篇 |
国内免费 | 19篇 |
学科分类
医药卫生 | 13098篇 |
出版年
2023年 | 93篇 |
2022年 | 123篇 |
2021年 | 290篇 |
2020年 | 168篇 |
2019年 | 249篇 |
2018年 | 295篇 |
2017年 | 233篇 |
2016年 | 196篇 |
2015年 | 262篇 |
2014年 | 342篇 |
2013年 | 494篇 |
2012年 | 657篇 |
2011年 | 669篇 |
2010年 | 399篇 |
2009年 | 323篇 |
2008年 | 554篇 |
2007年 | 592篇 |
2006年 | 582篇 |
2005年 | 527篇 |
2004年 | 508篇 |
2003年 | 478篇 |
2002年 | 445篇 |
2001年 | 305篇 |
2000年 | 282篇 |
1999年 | 245篇 |
1998年 | 142篇 |
1997年 | 125篇 |
1996年 | 91篇 |
1995年 | 111篇 |
1994年 | 96篇 |
1993年 | 65篇 |
1992年 | 235篇 |
1991年 | 210篇 |
1990年 | 205篇 |
1989年 | 164篇 |
1988年 | 180篇 |
1987年 | 140篇 |
1986年 | 165篇 |
1985年 | 159篇 |
1984年 | 124篇 |
1983年 | 111篇 |
1982年 | 68篇 |
1979年 | 103篇 |
1978年 | 92篇 |
1976年 | 65篇 |
1974年 | 71篇 |
1973年 | 83篇 |
1972年 | 88篇 |
1971年 | 66篇 |
1968年 | 64篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
David C Hatcher Cameron L Aboudara 《American journal of orthodontics and dentofacial orthopedics》2004,125(4):512-515
Accurate images of the craniofacial region are critical for the development of an orthodontic diagnosis and treatment plan. The NewTom QR 9000 Volume Scanner (QR s.r.l., Verona, Italy) represents a significant advance in imaging capabilities for dentistry and orthodontics. This new-generation scanner uses computed tomography technology to provide a complete 3D view of the maxilla and mandible with relatively high resolution and low radiation exposure to patients. This article discusses some technical aspects of this new scanner and its possible orthodontic uses. 相似文献
3.
T R Stolwijk J A van Best J P Boor H H Lemkes J A Oosterhuis 《Investigative ophthalmology & visual science》1990,31(3):436-439
Corneal epithelial permeability for fluorescein was determined after provocation by a local anesthetic in 18 non-insulin-dependent diabetes mellitus (NIDDM) patients, 23 insulin-dependent diabetes mellitus (IDDM) patients, and 22 healthy controls to evaluate the corneal epithelial barrier function in diabetes. All volunteers had Oxybuprocaine instilled into one eye and saline into the other eye. The epithelial permeability values were determined by fluorophotometry, and the ratio between both eyes was calculated for each individual. The mean permeability values of the saline-instilled eyes in the diabetic patients did not differ significantly from those in the healthy controls (P greater than 0.2). The individual ratios between Oxybuprocaine- and saline-instilled eyes in the NIDDM and IDDM patients differed significantly from those in the healthy controls (mean ratios: 2.6, 1.9, and 1.0, respectively; P less than 0.002). The permeability ratios and the percentage glycosylated hemoglobin (HbAlc) were linearly correlated in the NIDDM patients but not in the IDDM patients (r = 0.73, P less than 0.001, and r = 0.09, P greater than 0.68, respectively). The results showed that the corneal epithelial barrier function in the diabetic patients was not impaired compared with that in the healthy controls. After provocation by a local anesthetic, the barrier function was impaired in the diabetic patients only. 相似文献
4.
Chronic vitamin E treatment prevents defective endothelium-dependent relaxation in diabetic rat aorta 总被引:2,自引:2,他引:0
Summary We examined the effect in rats of 2 months of streptozotocin-induced diabetes mellitus on relaxation and contraction of aortas in vitro. A further diabetic group was treated from time of diabetes induction with a 1% dietary supplement of vitamin E. Diabetes caused a 26.5% deficit (p<0.001) in maximum endothelium-dependent relaxation to acetylcholine in phenylephrine-precontracted aortas. This was 64.3% attenuated (p<0.01) by vitamin E treatment; maximum relaxation was not significantly altered compared to non-diabetic rats. Vitamin E treatment of non-diabetic rats did not significantly affect acetylcholine-induced relaxation. Diabetes or treatment did not significantly alter acetylcholine sensitivity. Endothelium-independent relaxation response to glyceryl trinitrate was not affected by diabetes or vitamin E treatment, indicating that vascular smooth muscle responses to nitric oxide remained unaltered. There was a 35.4% reduction in the maximum contractile response to phenylephrine with diabetes (p<0.05) which was unaffected by vitamin E treatment. The data suggest that the chronic deficit in nitric oxide-mediated endothelium-dependent relaxation in diabetes depends largely upon excess activity of reactive oxygen species. Treatment with vitamin E to increase free radical scavenging specifically protected vascular endothelium although it had no effect on deficits in vascular smooth muscle contractile responses.Abbreviations NO
Nitric oxide
- ARI
aldose reductase inhibitor
- ACH
acetylcholine
- GTN
glyceryl trinitrate
- GSH
reduced form of glutathione
- EC50
effective concentration for 50% of the maximal response 相似文献
5.
The transport of L- and D-lactate into rat pancreatic islets and HIT-T15 insulinoma cells was studied by measuring uptake of 14C-labelled substrate at room temperature and by following changes in intracellular pH (pHi) in islets and HIT-T15 cells loaded with 2',7'-bis(carboxyethyl)-5'(6')-carboxyfluorescein (BCECF). Uptake of L-lactate into HIT-T15 cells was rapid, reaching equilibrium after 5 min with an apparent Km value of 4.8 mM. Transport was markedly inhibited by alpha-cyano-4-hydroxycinnamate, alpha-fluorocinnamate, quercetin and p-chloromercuribenzenesulphonate (pCMBS), and was enhanced in citrate medium. Uptake of D-lactate was less rapid, apparent equilibrium not being reached within 10 min. In contrast to HIT-T15 cells, rat pancreatic islets showed greatly reduced rates of transport of L- and D-lactate together with a correspondingly lower degree of inhibition by alpha-cyano-4-hydroxycinnamate. The addition of L- or D-lactate to HIT-T15 cells, but not dispersed islet cells, resulted in a marked and rapid intracellular acidification followed by a gradual recovery. In both HIT-T15 cells and isolated islets, the rates of transport of both L- and D-lactate in the presence of alpha-cyano-4-hydroxycinnamate were significantly greater in a depolarising K+ medium compared to the normal Na+ medium. These observations suggest that native rat islet cells have considerably reduced activity of the lactate-/H+ transport system compared to HIT-T15 insulinoma cells. There is evidence in both cell types of an additional electrogenic pathway for lactate which might play a role in coupling lactate efflux to beta-cell depolarisation. 相似文献
6.
7.
J Best 《The Medical journal of Australia》1986,144(8):438-439
8.
Carcinoma of the body and tail of the pancreas. 总被引:13,自引:0,他引:13
I H Nordback R H Hruban J K Boitnott H A Pitt J L Cameron 《American journal of surgery》1992,164(1):26-31
Recently, several institutions have reported improved results in the treatment of patients with carcinoma of the head of the pancreas. In an attempt to determine whether similar trends could be demonstrated for patients with carcinoma of the body and tail of the pancreas, the records of all 113 patients with an adenocarcinoma of the body or tail of the pancreas treated at The Johns Hopkins Hospital between 1972 and 1989 were reviewed. The patients were divided into two groups: those diagnosed between 1972 and 1982 (41 patients) and those between 1983 and 1989 (72 patients). No significant differences in tumor stage were observed between the two groups. The proportion of patients who underwent surgery decreased from 68% to 47% (p = 0.02). The number of patients who had bypass operations (15% versus 17%) or pancreatic resection (5% versus 10%) was similar in the two groups, but the proportion of patients who underwent exploratory laparotomy with biopsy only decreased from 49% to 21% (p = 0.002). The postoperative 30-day mortality (7% versus 3%), postoperative morbidity (18% versus 21%), median survival (4 months versus 3 months), and the 1-year survival (8% versus 9%) did not differ significantly between the two groups. One patient survived for 6 years after resection, and another patient is still alive 3 years after resection. Thus, unlike adenocarcinoma of the head of the pancreas, it appears that treatment results for patients with adenocarcinoma of the body or tail of the pancreas have not improved in recent years, the only change being a decreased need for exploratory laparotomy with biopsy only. 相似文献
9.
Adherence of Staphylococcus aureus to cultures of human peritoneal mesothelial cells 总被引:1,自引:0,他引:1
Glancey G.; Cameron J. S.; Ogg C.; Poston S. 《Nephrology, dialysis, transplantation》1993,8(2):157-162
Strains of Staphylococcus aureus, isolated from the effluentof patients with peritonitis on CAPD (continuous ambulatoryperitoneal dialysis), adhered well to both cultured human mesothelialcells and to fibronectin, but not to laminin or gelatin. Mesothelialcells grown in medium M199 exhibited more surface fibronectincompared to cells grown in MEM-Dval and demonstrated higherlevels of S. aureus adherence. Soluble fibronectin concentrations up to lOµg/ml increasedthe adherence of S. aureusto cultured mesothelial cells. Thedose-response curve was consistent with the binding of fibronectinto a saturable receptor of apparent dissociation constant (KD)= 1.7xlO10 M. This corresponds closely to the KD (2xlO10M) of the staphylococcal fibronectin-binding protein. S. aureus adherence was increased following the preincubationof mesothelial cell monolayers with interleukin-1 and was maximalafter 6 h preincubation. Treating mesothelial cells with interferon-gammafor 4872 h reduced the adherence of S. aureus. 相似文献
10.