全文获取类型
收费全文 | 920篇 |
免费 | 37篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 5篇 |
妇产科学 | 15篇 |
基础医学 | 95篇 |
口腔科学 | 14篇 |
临床医学 | 114篇 |
内科学 | 317篇 |
神经病学 | 122篇 |
特种医学 | 24篇 |
外科学 | 99篇 |
综合类 | 3篇 |
预防医学 | 52篇 |
眼科学 | 1篇 |
药学 | 59篇 |
中国医学 | 4篇 |
肿瘤学 | 25篇 |
出版年
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 8篇 |
2018年 | 10篇 |
2017年 | 11篇 |
2016年 | 7篇 |
2015年 | 18篇 |
2014年 | 16篇 |
2013年 | 23篇 |
2012年 | 48篇 |
2011年 | 47篇 |
2010年 | 22篇 |
2009年 | 25篇 |
2008年 | 41篇 |
2007年 | 39篇 |
2006年 | 50篇 |
2005年 | 51篇 |
2004年 | 44篇 |
2003年 | 55篇 |
2002年 | 43篇 |
2001年 | 36篇 |
2000年 | 48篇 |
1999年 | 32篇 |
1998年 | 12篇 |
1997年 | 9篇 |
1996年 | 14篇 |
1995年 | 11篇 |
1994年 | 10篇 |
1993年 | 4篇 |
1992年 | 17篇 |
1991年 | 16篇 |
1990年 | 20篇 |
1989年 | 19篇 |
1988年 | 22篇 |
1987年 | 21篇 |
1986年 | 10篇 |
1985年 | 15篇 |
1984年 | 11篇 |
1983年 | 11篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1970年 | 2篇 |
1969年 | 4篇 |
1968年 | 2篇 |
1967年 | 3篇 |
1965年 | 2篇 |
排序方式: 共有958条查询结果,搜索用时 15 毫秒
1.
The kinetics of insulin-mediated glucose uptake (IMGU) and non-insulin-mediated glucose uptake (NIMGU) in humans have not been well defined. We used the glucose-clamp technique to measure rates of whole-body and leg muscle glucose uptake in six healthy lean men during hyperinsulinemia (approximately 460 pM) to study IMGU and during somatostatin-induced insulinopenia to study NIMGU at four glucose levels (4.5, 9, 12, and 21 mM). To measure leg glucose uptake, the femoral artery and vein were catheterized, and blood flow was measured by thermodilution (leg glucose uptake = arteriovenous glucose difference [A-VG] x blood flow). With this approach, we found that, during hyperinsulinemia, both whole-body and leg glucose uptake increased in a curvilinear fashion at every glucose level, the highest glucose uptake values obtained being 139 +/- 17 mumol.kg-1.min-1 and 3656 +/- 931 mumol.min-1.leg-1, respectively. Leg blood flow increased twofold from 6.0 +/- 1.7 to 11.7 +/- 3.1 dl/min (P less than 0.01) over the range of glucose and was correlated with whole-body glucose uptake (r = 0.55, P less than 0.005). Leg muscle glucose extraction, independent of changes in blood flow, which is reflected by the A-VG, saturated over the range of glucose (1.28 +/- 0.12, 2.22 +/- 0.30, 2.92 +/- 0.42, 3.02 +/- 0.41 mM, NS between last 2 values) with a half-maximal effective glucose concentration (EG50) of 5.3 +/- 0.4 mM.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
2.
Knee-chest vs horizontal side position during induction of spinal anaesthesia in patients undergoing lumbar disc surgery 总被引:1,自引:1,他引:0
Laakso E.; Pitkanen M.; Kytta J.; Rosenberg P. H. 《British journal of anaesthesia》1997,79(5):609-611
In the prone knee-chest position the spread of plain 0.5% bupivacaine in
the cerebrospinal fluid and associated haemodynamic changes may be
different compared with the horizontal position. A randomized comparison
was performed in 40 ASA I-II patients, aged 24-61 yr, undergoing lumbar
disc surgery. Subarachnoid injection (27-gauge needle) at the L2-3
interspace with 3 ml of 0.5% bupivacaine was performed with the patient in
the operative knee-chest position (prone knee-chest group, n = 20) or in
the horizontal side position (supine side horizontal group, n = 20).
Patients in the supine side horizontal group were turned into the
horizontal supine position for 20 min, and subsequently they were placed in
the operative knee-chest position. In three patients in the prone
knee-chest group, the spinal needle was replaced by a larger needle
(25-gauge). The final cephalad extension of sensory analgesia on skin
tested by pinprick was T5 (median) in the prone knee-chest group and T6 in
the supine side horizontal group. Recovery was also similar, on average 210
min from injection in both groups. The mean decrease in systolic arterial
pressure was somewhat greater in the prone knee-chest group (30 mm Hg) than
in the supine side horizontal group (13 mm Hg). The need for ephedrine
occurred earlier in the supine side horizontal group (three patients, all
within 10 min from local anaesthetic injection) than in the prone
knee-chest group (six patients, all after 15 min). Four of the latter
patients also required administration of an anticholinergic for bradycardia
compared with two patients in the supine side horizontal group. Light
sedation was given to five patients in the prone knee-chest group and to
four in the supine side horizontal group because of numbness and aching in
the shoulders. We conclude that spinal block was similar in the two groups
but there was a tendency to more frequent episodes of haemodynamic
deterioration in the knee-chest position.
相似文献
3.
Chromium supplementation in impaired glucose tolerance of elderly: effects on blood glucose, plasma insulin, C-peptide and lipid levels. 总被引:1,自引:0,他引:1
M I Uusitupa L Mykk?nen O Siitonen M Laakso H Sarlund P Kolehmainen T R?s?nen J Kumpulainen K Py?r?l? 《The British journal of nutrition》1992,68(1):209-216
Altogether twenty-six elderly subjects (aged 65-74 years) with persistent impaired glucose tolerance (World Health Organization (1985) criteria) identified in a population-based study, were randomly treated either with chromium-rich yeast (160 micrograms Cr/d) or with placebo for 6 months. The 24 h urinary Cr increased from 0.13 (SE 0.03) to 0.40 (SE 0.06) micrograms/d in the Cr group (n 13) but no change was found in the placebo group (n 11) (0.13 (SE 0.02) v. 0.11 (SE 0.02) micrograms/d). No significant change was observed in the oral glucose tolerance test (glucose dose 75 g; 0, 1 and 2 h blood glucose respectively): 5.3 (SE 0.1), 9.3 (SE 0.3), 8.2 (SE 0.3) mmol/l v. 5.0 (SE 0.1), 8.5 (SE 0.4), 7.3(SE 0.5) mmol/l in the Cr group; 4.9 (SE 0.2), 9.2 (SE 0.6), 8.1 (SE 0.3) mmol/l v. 4.8 (SE 0.2), 8.5 (SE 0.5), 7.0 (SE 0.6) mmol/l in the placebo group (baseline v. 6 months). Glycosylated haemoglobin, plasma insulin, C-peptide and apolipoprotein A1 and B levels remained unchanged, and no improvement was seen in serum total cholesterol (6.2 (SE 0.3) v. 6.4 (SE 0.3) mmol/l for the Cr group, 6.2 (SE 0.4) v. 6.5 (SE 0.3) mmol/l for the placebo group), high-density-lipoprotein-cholesterol (1.1 (SE 0.1) v. 1.2 (SE 0.1) mmol/l for the Cr group, 1.0 (SE 0.1) v. 1.1 (SE 0.1) mmol/l for the placebo group) or triacylglycerols (2.5 (SE 0.4) v. 2.0 (SE 0.4) mmol/l for the Cr group, 2.4 (SE 0.2) v. 2.5 (SE 0.2) mmol/l for the placebo group). The present results indicate that Cr supplementation does not improve glucose tolerance or serum lipid levels in elderly subjects with stable impaired glucose tolerance. 相似文献
4.
Natural lighting differs from usual artificial lighting mainly as follows: it has larger spectral composition, fluctuations of intensity during the day, higher intensity levels during the night (moonlight, starlight), and gradual changes of illuminance at dawn and dusk. The present experiment was performed in order to study whether these features of lighting affect the 24-hour patterns of melatonin and prolactin in male rats. The rats were kept 7 days in 'natural' lighting (sunlight through windows) or in artificial lighting (cool white fluorescent lamps) of similar periodicities (13/11 h light/dark). The samples were collected at 3-hour intervals during a 24-hour period. Pineal melatonin contents, pituitary prolactin contents, and plasma prolactin concentrations were measured radioimmunologically. The nocturnal pineal melatonin contents were higher and the daytime contents lower in natural than in artificial lighting conditions. A corresponding 'strengthening of rhythm' of prolactin was found in natural lighting. A reason for the higher amplitude variation of melatonin in the natural lighting conditions may be the gradual changes of illuminance at dawn and dusk. The different pituitary and plasma prolactin patterns of the rats kept in the two lighting conditions might partly be explained by a stimulatory effect of melatonin on the production and secretion of prolactin, but other regulatory factors had to be involved, too. 相似文献
5.
Response to a diet low in total fat in women with postmenopausal breast cancer: a pilot study 总被引:1,自引:0,他引:1
A P Boyar D P Rose J R Loughridge A Engle A Palgi K Laakso D Kinne E L Wynder 《Nutrition and cancer》1988,11(2):93-99
A feasibility study was instituted to determine if women with postmenopausal breast cancer would follow a low-fat diet (20% of kcal) for at least four months. Nineteen women, whose baseline food intake was 1,504 +/- 420 kcal with 56 +/- 16 g of fat, reported a decrease in fat intake to 21 +/- 6 g after two months of dietary intervention. Serum concentrations of cholesterol, HDL cholesterol, and estradiol were significantly reduced by the fifth month on the diet. We conclude that self-selected patients can adhere to a low-fat diet, and that serum cholesterol may serve as an indicator of dietary compliance. 相似文献
6.
7.
A high-molecular-weight fraction of smooth lipopolysaccharide in Klebsiella serotype O1:K20 contains a unique O-antigen epitope and determines resistance to nonspecific serum killing 总被引:11,自引:2,他引:11 下载免费PDF全文
K L McCallum G Schoenhals D Laakso B Clarke C Whitfield 《Infection and immunity》1989,57(12):3816-3822
The lipopolysaccharide (LPS) O-antigen side chains of Klebsiella serotype O1 have been studied by using mutants selected by resistance to a Klebsiella bacteriophage designated O1-A. Two classes of LPS mutants were identified. The major group (90%) synthesized rough LPS. The remaining 10% of the mutants produced a novel LPS profile that lacked the highest-molecular-weight O-substituted molecules (HMW-LPS) but still produced lower-molecular-weight O-substituted species (LMW-LPS). By using antisera raised against mutant Klebsiella strains and antiserum specific for Pasteurella haemolytica serotype 4, it was demonstrated that HMW-LPS and LMW-LPS contain shared epitopes. HMW-LPS also contained an epitope absent in LMW-LPS. This unique epitope was recognized by a monoclonal antibody (O1-52.6) and appears to be responsible for the serological cross-reaction between the O antigens of Klebsiella O1 and Escherichia coli O19. This HMW-LPS epitope was present in eight other Klebsiella O1 isolates which were examined. Electron microscopy demonstrated that HMW-LPS excluded overlying capsular polysaccharide for a distance of 25 to 40 nm. The distance was reduced to 10 to 18 nm in strains which synthesized only LMW-LPS and to zero in rough LPS strains. The HMW-LPS of Klebsiella O1 was shown to be an important virulence determinant, since this molecule was responsible for the resistance of the bacterium to nonspecific, complement-mediated serum killing. 相似文献
8.
9.
Plasma levels of TSH and thyroid hormones in 22 male and 27 female medical students were determined by radioimmunoassay before and after an academic examination. The plasma values of TSH were slightly higher in both sexes on the examination day than on the control days. The values were lower after the examination than before it in females but not in males. Plasma levels of T3 were higher in males than in females on the examination day. In contrast, the plasma rT3 values were higher for females on the examination day than on control days. The plasma levels of T4 were similar in both sexes. The results suggest that during psychic stress, the pituitary-thyroid endocrine system of the female reacts differently from that of the male. 相似文献
10.