全文获取类型
收费全文 | 24820篇 |
免费 | 1972篇 |
国内免费 | 42篇 |
专业分类
耳鼻咽喉 | 294篇 |
儿科学 | 875篇 |
妇产科学 | 575篇 |
基础医学 | 3372篇 |
口腔科学 | 704篇 |
临床医学 | 2953篇 |
内科学 | 4294篇 |
皮肤病学 | 361篇 |
神经病学 | 2262篇 |
特种医学 | 796篇 |
外国民族医学 | 1篇 |
外科学 | 3989篇 |
综合类 | 494篇 |
一般理论 | 13篇 |
预防医学 | 2416篇 |
眼科学 | 634篇 |
药学 | 1353篇 |
中国医学 | 6篇 |
肿瘤学 | 1442篇 |
出版年
2022年 | 169篇 |
2021年 | 373篇 |
2020年 | 230篇 |
2019年 | 377篇 |
2018年 | 500篇 |
2017年 | 349篇 |
2016年 | 329篇 |
2015年 | 402篇 |
2014年 | 664篇 |
2013年 | 920篇 |
2012年 | 1297篇 |
2011年 | 1357篇 |
2010年 | 795篇 |
2009年 | 675篇 |
2008年 | 1150篇 |
2007年 | 1262篇 |
2006年 | 1223篇 |
2005年 | 1285篇 |
2004年 | 1195篇 |
2003年 | 1107篇 |
2002年 | 1006篇 |
2001年 | 575篇 |
2000年 | 579篇 |
1999年 | 528篇 |
1998年 | 298篇 |
1997年 | 219篇 |
1996年 | 224篇 |
1995年 | 197篇 |
1994年 | 212篇 |
1993年 | 195篇 |
1992年 | 481篇 |
1991年 | 403篇 |
1990年 | 383篇 |
1989年 | 367篇 |
1988年 | 362篇 |
1987年 | 321篇 |
1986年 | 336篇 |
1985年 | 334篇 |
1984年 | 256篇 |
1983年 | 267篇 |
1982年 | 195篇 |
1981年 | 213篇 |
1980年 | 183篇 |
1979年 | 284篇 |
1978年 | 214篇 |
1977年 | 175篇 |
1975年 | 165篇 |
1974年 | 208篇 |
1973年 | 215篇 |
1972年 | 169篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
V Allen PhD DW Ryan MB FRCA A Murray PhD FIPSM 《International journal of clinical practice》1994,48(3):125-129
SUMMARY Four specialised air mattresses had interface pressure measured under six body sites prone to pressure sores in 10 subjects, supine and sitting. The mattresses were the Clinirest (SSI) and FirstStep (KCI) continuous airflow mattress overlays, and Airwave (Pegasus) and Nimbus (Huntleigh) alternating pressure air mattresses. On the mattress overlays, average supine interface pressures were 2.33 kPa (scapula), 4.15 kPa (elbow), 1.94 kPa (sacrum) and 2.79 kPa (buttock), although they were higher at the occiput (7.97 kPa) and heel (11.7 kPa). The alternating pressure air mattresses had an average minimum interface pressure close to zero for three sites, rising to 4.28 kPa under the heel. Average maximum interface pressures were 8.61 kPa (occiput), 5.21 kPa (scapula), 4.90 (elbow), 4.85 kPa (sacrum), 4.61 kPa (buttock) and 13.2 kPa (heel). No accepted scientific method exists for comparing the two types of mattress. Our data suggest a clinical benefit at the occiput and heel (supine) in using an alternating pressure air mattress and a benefit in using a continuous airflow mattress overlay at other sites. 相似文献
62.
Martin E. Weinand Bruce Hermann Allen R. Wyler L. Philip Carter K. J. Oommen David Labiner Geoff Ahern Anne Herring 《Epilepsia》1994,35(5):1054-1059
Summary: We report a series of 8 patients with ictal déjà vu. Subdural strip electrocorticographic (ECoG) monitoring localized the ictal epileptogenic focus as follows: right (n = 6) and left (n = 2) mesiotemporal lobe. In all 8 patients, the left hemisphere was dominant for language function based on intracarotid amytal testing. In 6 right-handed patients, ictal déjà vu was associated with a right temporal lobe focus. However, in the 2 left-handed patients, the ictal focus was left temporal lobe. Although ictal déjà vu localizes the epileptic focus to temporal lobe, this experiential phenomenon appears to lateralize to the hemisphere nondominant for handedness. 相似文献
63.
C Allen C F Stevens 《Proceedings of the National Academy of Sciences of the United States of America》1994,91(22):10380-10383
Transmission at individual synaptic contacts on CA1 hippocampal pyramidal neurons has been found to be very unreliable, with greater than half of the arriving presynaptic nerve impulses failing to evoke a postsynaptic response. This conclusion has been reached using the method of minimal stimulation of Schaffer collaterals and whole cell recording in hippocampal slices; with minimal stimulation only one or a few synapses are activated on the target neuron and the behavior of individual synapses can be examined. Four sources for the unreliability of synaptic transmission have been investigated: (i) the fluctuation of axon thresholds at the site of stimulation causing the failure to generate a nerve impulse in the appropriate Schaffer collaterals, (ii) the failure of nerve impulses generated at the site of stimulation to arrive at the synapse because of conduction failures at axon branch points, (iii) an artifactual synaptic unreliability due to performing experiments in vitro at temperatures well below the normal mammalian body temperature, and (iv) transmission failures due to probabilistic release mechanisms at synapses with a very low capacity to release transmitter. We eliminate the first three causes as significant contributions and conclude that probabilistic release mechanisms at low capacity synapses are the main cause of unreliability of synaptic transmission. 相似文献
64.
以双蒂腹壁下动脉穿支皮瓣再造乳房 总被引:6,自引:1,他引:5
目的 报道对有纵形剖腹产瘢痕的乳腺癌根治术后所造成的胸壁畸形,应用双蒂腹壁下动脉穿支皮瓣再造乳房的临床效果,从而说明胸廓内动脉远心端供血的可靠性。方法 应用游离的双侧腹壁下动静脉为蒂的腹壁下动脉穿支皮瓣与胸廓内动、静脉远近心断端分别进行端端吻合再造乳房4例。结果 临床应用4例,皮瓣全部成活,再造乳房的形态较满意。术后随访l0~26个月,无腹部薄弱或腹壁疝等并发症发生。结论 胸廓内动、静脉可提供远近心端两组可靠的受区血管。以双侧腹壁下动、静脉为蒂的横行腹壁下动脉穿支皮瓣,适用于乳腺癌根治术后的乳房再造,特别适用于有纵形剖腹产瘢痕及腹壁较薄者的整形修复。 相似文献
65.
Joseph R. Ghilardi Clark J. Allen Steven R. Vigna Douglas C. McVey Patrick W. Mantyh 《Brain research》1994,633(1-2)
A [125I]cholecystokinin (CCK) analog and [125I]peptide YY (PYY) were used to localize and characterize CCK and neuropeptide Y (NPY) receptor binding sites in the rabbit vagal afferent (nodose) ganglion. High concentrations of CCK and NPY binding sites were observed in 10.6% and 9.2% of the nodose ganglion neurons, respectively. Pharmacological experiments using CCK or NPY analogs suggest that both subtypes of CCK (CCK-A and CCK-B) and NPY (Y1 and Y2) receptor binding sites are expressed by discrete populations of neurons in the nodose ganglion. These results suggest sites at which CCK or NPY, released in either the nucleus of the solitary tract or a peripheral tissue, may modulate the release of neurotransmitters from a select population of visceral primary afferent neurons. Possible functions mediated by these receptors include modulation of satiety, opiate analgesia, and the development of morphine tolerance. 相似文献
66.
A case of an ovarian serous epithelial neoplasm of borderline type admixed with sarcomatous elements is reported. This combination seems to be extremely rare with only four cases previously reported. It may represent a type of collision tumour or the development of a sarcoma in a growth with borderline differentiation. 相似文献
67.
Douglas M. Howarth Martin T. Epstein Paul A. Thomas Leonard W. Allen Rachel Akerman Linda Lan 《European journal of nuclear medicine and molecular imaging》1997,24(12):1465-1469
The efficacy of fractionated out-patient radioiodine therapy in 38 patients with compressive symptoms due to long-standing
large multinodular goitres was assessed. The diagnosis was established by clinical assessment in addition to technetium-99m
pertechnetate thyroid scan or computed tomography scan of the thyroid and mediastinum. Oral iodine-131 therapy was administered
as a 2.22 GBq (60 mCi) cumulative dose over 4 months (555 MBq per month). All patients were monitored with serum thyroid-stimulating
hormone and free thyroxine (± free tri-iodothyronine) assays before the treatment and after each dose fraction. Clinical and
biochemical follow-up was performed on all patients and ranged from 6 to 45 months after therapy. The patients consisted of
35 female and three male patients with a median age of 59 years (range 37–87 years). Prior to treatment 20 patients were biochemically
hyperthyroid and 18 were euthyroid. Overall, 71% of patients reported a subjective improvement in compressive symptoms and
29% reported no change. Clinically assessed reduction in goitre size occurred in 92% of patients while there was no change
in 8%. At 3 months of follow-up, 31% of patients had become hypothyroid and at 18 months 66% were hypothyroid. Seven hyperthyroid
patients (35%) became euthyroid and 13 hyperthyroid patients (65%) became hypothyroid. Three patients who became hypothyroid
experienced neck soreness (transient in one patient, persistent in two patients). There were no differences in outcome between
patients who were hyperthyroid and those who were euthyroid prior to treatment. Fractionated out-patient radioiodine therapy
showed excellent short- and medium-term safety, was very well tolerated and offered a satisfactory alternative treatment to
surgery.
Received 23 May and in revised form 11 August 1997 相似文献
68.
The relationship of perceived control over daily uplifts and hassles to depression and restraint was examined in a sample of 140 middle-class sixth graders. Results indicated that greater control over uplifts was associated with better functioning and lower control over hassles with poorer functioning, even after partialing out the respective number of uplifts and hassles reported. Moreover, when directly compared, control over uplifts showed more powerful associations with adaptational outcomes than did control over hassles. In a separate analysis, the number of uplifts over which children reported high control showed opposite relationships to adaptational outcomes than did the number of uplifts over which children reported low control. A different pattern appeared for hassles. Although the number of hassles with low control was associated with poorer functioning, the number of hassles over which children had high control was unrelated to adaptational outcomes. The possibility that control operates somewhat differently for positive and negative events is discussed.This research was supported by a grant to the second author from the Stanford Center for the Study of Families, Children and Youth. The authors are grateful to Rachelle Hacket for data analysis, Tom Gehring for data collection, and Susan Nolen-Hoeksema for critical comments. 相似文献
69.
Effect of dietary zinc deficiency on the endogenous phosphorylation and dephosphorylation of rat erythrocyte membrane 总被引:1,自引:0,他引:1
The effect of dietary zinc deficiency on patterns of phosphorylation and dephosphorylation of rat erythrocyte membrane proteins and erythrocyte filterability was examined. Weanling male Wistar rats were fed an egg white-based diet containing less than 1.1 mg zinc/kg diet ad libitum for 3 wk. Control rats were either pair-fed or ad libitum-fed the basal diet supplemented with 100 mg zinc/kg diet. Net phosphorylation and dephosphorylation of erythrocyte membrane proteins were carried out by an in vitro assay utilizing [gamma-32P]ATP. The membrane proteins were subsequently separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the 32P content of gel slices was counted by Cerenkov counting. Erythrocyte filterability was measured as the filtration time of suspensions of erythrocytes, both untreated and preincubated with diamide, under constant pressure. Erythrocyte ghosts from zinc-deficient rats demonstrated greater dephosphorylation of protein bands R1 plus R2 and R7 than pair-fed rats and greater net phosphorylation of band R2.2 than pair-fed or ad libitum-fed control rats (P less than 0.05). Erythrocytes from ad libitum-fed control rats showed significantly longer filtration times than those from zinc-deficient or pair-fed control rats. In conclusion, dietary zinc deficiency alters in vitro patterns of erythrocyte membrane protein phosphorylation and dephosphorylation, whereas the depression in food intake associated with the zinc deficiency increases erythrocyte filterability. 相似文献
70.
Isobel Allen 《British medical journal》2005,331(7516):569-572