全文获取类型
收费全文 | 20635篇 |
免费 | 1593篇 |
国内免费 | 45篇 |
学科分类
医药卫生 | 22273篇 |
出版年
2021年 | 308篇 |
2020年 | 202篇 |
2019年 | 318篇 |
2018年 | 373篇 |
2017年 | 277篇 |
2016年 | 303篇 |
2015年 | 327篇 |
2014年 | 499篇 |
2013年 | 793篇 |
2012年 | 1108篇 |
2011年 | 1231篇 |
2010年 | 633篇 |
2009年 | 609篇 |
2008年 | 1106篇 |
2007年 | 1113篇 |
2006年 | 1208篇 |
2005年 | 1129篇 |
2004年 | 1195篇 |
2003年 | 1128篇 |
2002年 | 1039篇 |
2001年 | 442篇 |
2000年 | 412篇 |
1999年 | 419篇 |
1998年 | 246篇 |
1997年 | 213篇 |
1996年 | 155篇 |
1995年 | 188篇 |
1994年 | 143篇 |
1993年 | 138篇 |
1992年 | 336篇 |
1991年 | 316篇 |
1990年 | 299篇 |
1989年 | 292篇 |
1988年 | 260篇 |
1987年 | 307篇 |
1986年 | 282篇 |
1985年 | 243篇 |
1984年 | 207篇 |
1983年 | 190篇 |
1982年 | 124篇 |
1981年 | 138篇 |
1980年 | 127篇 |
1979年 | 170篇 |
1978年 | 136篇 |
1977年 | 117篇 |
1976年 | 102篇 |
1974年 | 104篇 |
1973年 | 119篇 |
1972年 | 107篇 |
1971年 | 101篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
51.
52.
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
53.
Persistent asthma after accidental exposure to ethylene oxide. 总被引:2,自引:0,他引:2
54.
Hypothesis: Pathogenesis of postmenopausal hot flush 总被引:1,自引:0,他引:1
The pathogenesis of postmenopausal hot flush is still poorly understood. A hypothesis is presented where the perimenopausal decline in circulating estrogen levels may increase central norepinephrine and LH-RH secretion and produce a downward setting of the central thermostat resulting in a hot flush. 相似文献
55.
Lynn R. Sorbara Zhichun Tang Alessandro Cama Jinru Xia Esther Schenker Ronald A. Kohanski Leonid Poretsky Elizabeth Koller Simeon I. Taylor Andrea Dunaif 《Metabolism: clinical and experimental》1994,43(12)
Women with polycystic ovary syndrome (PCOS) are markedly insulin-resistant, but the molecular mechanisms of these changes and their relationship to the hyperandrogenic state remain to be clarified. Mutations have recently been identified in the insulin receptor gene of patients with extreme forms of insulin resistance associated with hyperandrogenism (eg, type A insulin resistance), and these mutations account for the insulin resistance in such patients. We performed this study to determine whether mutations in the coding portion of the insulin receptor gene were responsible for insulin resistance in PCOS. Insulin binding studies using cultured skin fibroblasts of three obese (body mass index > 27 kg/m2) women with PCOS (ie, mild hyperandrogenemia and chronic anovulation of unknown etiology) and documented insulin resistance showed no apprarent abnormalities in either the number or affinity of insulin binding sites. Direct sequencing of all 22 exons of the insulin receptor gene from two of the women with PCOS did not reveal any mutations. Furthermore, both alleles of the gene were expressed at equal levels. In a third insulin-resistant PCOS woman, there was no evidence for a mutation in the coding portion of the insulin receptor gene as determined by denaturing gradient gel electrophoresis (DGGE). We conclude that the insulin resistance in these PCOS women was caused by a defect extrinsic to the insulin receptor. 相似文献
56.
The effect of thoracic (T7-8) epidural etidocaine 1.5%, 9 ml, and continuous per- and postoperative epidural infusion of etidocaine 1.5%, 4 ml/h, on early (less than 500 ms) somatosensory evoked potentials (SEPs), and cortisol and glucose in plasma during cholecystectomy, was examined in ten patients. Spread of analgesia (pin-prick) was T3 (T1-T3) to L2 (T11-L3) 35 min after injection of etidocaine, and T3 (T2-T4) to T12 (T8-L4) 3 h after surgical incision (median (range)). Before operation, epidural etidocaine had no significant effects on peak-to-peak amplitude of SEPs to electrical stimulation at the L1, T10 or T6 dermatomal level (P greater than 0.09). SEPs were abolished in only two patients at T6, and no patient had SEPs abolished at T10 or L1. The plasma concentrations of cortisol and glucose were significantly increased 20 min after surgical incision and remained increased throughout the study. No correlation was found between the block-induced decrease in the peak-to-peak amplitude at T6 or T10 and increase in plasma cortisol, except for a negative correlation at T10 and the initial increase in cortisol (Rs = 0.72, P = 0.03). In conclusion, thoracic epidural administration of 9 ml of etidocaine 1.5% does not provide total afferent somatic blockade assessed by SEP and the stress response to cholecystectomy. 相似文献
57.
Lynn Ware M.D. Dr. David Muram M.D. Christine L. Gale M.D. 《Sexuality and disability》1992,10(3):189-192
In some patients with mental retardation, a Q-tip pap smear obtained blindly from the upper vagina may be the only cytologic smear obtainable without subjecting the patient to heavy sedation or to examination under anesthesia. The efficacy of blind Q-tip smears has not been previously determined. Of 31 Q-tip smears obtained from patients with CIN, the Q-tip smear identified the abnormality in 10 (32%) patients. For those patients who will not submit to examination without anesthesia or sedation, routine screening with multiple smears, obtained on an annual basis has the potential to identify many cases of CIN which otherwise would not be identified at all, and in certain patients, this method outweighs the risks of heavy sedation or general anesthesia. Because of the greatly reduced sensitivity of the Q-tip pap, every effort should be made to help the patient and/or her family or guardian to understand the implications and risks of this method. However, if an examination under anesthesia is performed for other indications, a complete gynecologic examination and a direct smear should be obtained at that time. 相似文献
58.
59.
Role of antithrombin III as a regulator of in vivo coagulation 总被引:5,自引:0,他引:5
60.