首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   24538篇
  免费   1977篇
  国内免费   44篇
耳鼻咽喉   276篇
儿科学   875篇
妇产科学   574篇
基础医学   3334篇
口腔科学   692篇
临床医学   2927篇
内科学   4271篇
皮肤病学   361篇
神经病学   2252篇
特种医学   800篇
外国民族医学   1篇
外科学   3932篇
综合类   506篇
一般理论   13篇
预防医学   2374篇
眼科学   606篇
药学   1347篇
中国医学   6篇
肿瘤学   1412篇
  2021年   369篇
  2020年   225篇
  2019年   369篇
  2018年   495篇
  2017年   344篇
  2016年   326篇
  2015年   404篇
  2014年   660篇
  2013年   920篇
  2012年   1286篇
  2011年   1348篇
  2010年   792篇
  2009年   686篇
  2008年   1155篇
  2007年   1252篇
  2006年   1215篇
  2005年   1274篇
  2004年   1171篇
  2003年   1090篇
  2002年   1001篇
  2001年   564篇
  2000年   570篇
  1999年   520篇
  1998年   303篇
  1997年   224篇
  1996年   232篇
  1995年   196篇
  1994年   216篇
  1993年   205篇
  1992年   478篇
  1991年   402篇
  1990年   372篇
  1989年   364篇
  1988年   358篇
  1987年   316篇
  1986年   334篇
  1985年   329篇
  1984年   255篇
  1983年   262篇
  1982年   195篇
  1981年   212篇
  1980年   184篇
  1979年   278篇
  1978年   213篇
  1977年   174篇
  1975年   163篇
  1974年   199篇
  1973年   211篇
  1972年   163篇
  1971年   160篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
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   
82.
An evaluation of causes for unreliability of synaptic transmission.   总被引:21,自引:2,他引:19       下载免费PDF全文
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   
83.
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   
84.
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   
85.
Combined high grade sarcoma and serous ovarian neoplasm.   总被引:1,自引:0,他引:1       下载免费PDF全文
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   
86.
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   
87.
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   
88.
A phase II trial of fludarabine phosphate using a bolus and continuous infusion regimen in previously treated multiple myeloma was performed. No responses were observed in eleven patients. There was no significant non-hematologic toxicity noted. Fludarabine phosphate is inactive in multiple myeloma using this schedule.  相似文献   
89.
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   
90.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号