全文获取类型
收费全文 | 1788篇 |
免费 | 116篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 64篇 |
妇产科学 | 52篇 |
基础医学 | 165篇 |
口腔科学 | 77篇 |
临床医学 | 135篇 |
内科学 | 386篇 |
皮肤病学 | 18篇 |
神经病学 | 94篇 |
特种医学 | 214篇 |
外科学 | 296篇 |
综合类 | 84篇 |
预防医学 | 107篇 |
眼科学 | 10篇 |
药学 | 97篇 |
中国医学 | 35篇 |
肿瘤学 | 71篇 |
出版年
2022年 | 23篇 |
2021年 | 32篇 |
2020年 | 16篇 |
2019年 | 27篇 |
2018年 | 42篇 |
2017年 | 30篇 |
2016年 | 26篇 |
2015年 | 40篇 |
2014年 | 69篇 |
2013年 | 106篇 |
2012年 | 119篇 |
2011年 | 112篇 |
2010年 | 82篇 |
2009年 | 62篇 |
2008年 | 82篇 |
2007年 | 92篇 |
2006年 | 64篇 |
2005年 | 55篇 |
2004年 | 58篇 |
2003年 | 38篇 |
2002年 | 53篇 |
2001年 | 34篇 |
2000年 | 37篇 |
1999年 | 34篇 |
1998年 | 67篇 |
1997年 | 51篇 |
1996年 | 41篇 |
1995年 | 29篇 |
1994年 | 29篇 |
1993年 | 27篇 |
1992年 | 24篇 |
1991年 | 24篇 |
1990年 | 16篇 |
1989年 | 31篇 |
1988年 | 32篇 |
1987年 | 26篇 |
1986年 | 16篇 |
1985年 | 27篇 |
1984年 | 13篇 |
1983年 | 17篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 15篇 |
1978年 | 8篇 |
1977年 | 8篇 |
1976年 | 11篇 |
1975年 | 8篇 |
1972年 | 5篇 |
1971年 | 5篇 |
1947年 | 5篇 |
排序方式: 共有1914条查询结果,搜索用时 15 毫秒
1.
Intracranial circulation: pulse-sequence considerations in three- dimensional (volume) MR angiography 总被引:2,自引:0,他引:2
The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study. 相似文献
2.
B M Cohen G Stramentinoli A L Sosa S M Babb V Olgiati 《European journal of pharmacology》1989,170(3):201-207
alpha 1- and beta-adrenoceptors were studied ex vivo in the brains of rats receiving repeated daily treatment with the standard antidepressant imipramine or the atypical antidepressant S-adenosyl-L-methionine (SAM), which has minimal effects on monoamine reuptake or turnover. Consistent with past studies, a decrease in the density of beta receptors at three weeks and an increase in the affinity of alpha 1 receptors for the agonist phenylephrine at one week of treatment was observed with imipramine. By comparison, an increase in the density of beta receptors and a decrease in the affinity of alpha 1 receptors for phenylephrine was observed at one week of treatment with SAM. These changes were no longer apparent at three weeks of treatment. The results suggest that treatment with SAM does lead to changes in adrenergic neurotransmission, but that down regulation of beta receptors or increased agonist affinity of alpha 1 receptors may not be necessary for the production of antidepressant effects. 相似文献
3.
Manuel Sosa P. Saavedra J. del Pino-Montes J. Alegre R. Pérez-Cano G. Martínez Díaz Guerra M. Díaz-Curiel C. Valero M. Muñoz-Torres A. Torrijos J. Mosquera C. Gómez-Alonso GIUMO Study Group 《Journal of clinical densitometry》2005,8(4):430-435
Measurement of ultrasonographic parameters provides information concerning not only bone density but also bone architecture. We investigated the usefulness of ultrasonographic parameters and bone mineral density (BMD) to evaluate the probability of Colles' fracture. Two-hundred eighty-nine postmenopausal women (62.3 +/- 8.7 yr) with (n = 76) and without (n = 213) Colles' fracture were studied. BMD of lumbar spine and proximal femur was evaluated in all women by dual-energy X-ray absorptiometry (DXA) and speed of sound (SOS), broadband ultrasound attenuation (BUA), and stiffness in the calcaneus were measured by a Sahara ultrasonometer (Hologic). Patients suffering from Colles' fracture had lower values of BMD adjusted by height at the lumbar spine, L2-L4 (0.797 g/cm2 vs 0.860 g/cm2), femoral neck (0.685 g/cm2 vs 0.712 g/cm2 ), SOS (1518 m/sg vs 1525 m/sg), and stiffness (74.6 vs 77.7) (p < 0.05). Nevertheless, BUA values were similar in both groups. After stepwise logistic regression analysis, the area found under receiver operating characteristic (ROC) curves was 0.60 for L2L4 and 0.63 for a formula combining L2L4 and height. Our data suggest that patients suffering from Colles' fracture have lower values of BMD by DXA, SOS, and stiffness. However, the ability of these techniques to discriminate is low because the values for the area under ROC curve are 0.60 for L2-L4 and 0.63 for a formula derived of the combination of L2-L4 and height. 相似文献
4.
Maxillary sinusitis in adults: an evaluation of placebo-controlled double-blind trials 总被引:1,自引:0,他引:1
BACKGROUND: In general practice, acute sinusitis is frequently diagnosed
and treated with antibiotics. OBJECTIVE: This study aimed to determine the
evidence for the effectiveness of antibiotic treatment in acute maxillary
sinusitis in adults by assessing the methodological quality of
placebo-controlled double-blind randomized trials. METHOD: An evaluation by
four raters through a 35-item scoring-scale for internal and external
validity of all placebo-controlled double-blind randomized trials on acute
sinusitis found between January 1966 and July 1996. RESULTS: Eighty-five
trials were excluded because they were not placebo-controlled,
double-blind, randomized, or were carried out in patients with chronic
sinusitis or in children. The three remaining trials were performed in
different populations (one in general practice) between 1973 and 1978. Only
one study claimed superiority of antibiotic treatment. Different inclusion
criteria and major outcome measures were used by the authors. The
reliability of major outcome events was reported poorly or not at all and
in two studies outcome measures were clinically inappropriate. The studies
scored 30-62% of the maximum attainable score for internal validity and
10-20% for external validity. CONCLUSION: The effectiveness of antibiotic
treatment in acute maxillary sinusitis in a general practice population is
not based sufficiently on evidence.
相似文献
5.
Hand-assisted laparoscopic nephroureterectomy for upper urinary tract transitional cell carcinoma. 总被引:1,自引:0,他引:1
Jay D Raman Michael A Palese Casey K Ng Stephen A Boorjian Douglas S Scherr Joseph J Del Pizzo R Ernest Sosa 《JSLS, Journal of the Society of Laparoendoscopic Surgeons》2006,10(4):432-438
OBJECTIVE: We report our experience with hand-assisted laparoscopic nephroureterectomy (HALN) for upper urinary tract transitional cell carcinoma and compare our results with a contemporary series of open nephroureterectomy (ON) performed at our institution. METHODS: Between August 1996 and May 2003, 90 patients underwent nephroureterectomy for upper-tract transitional cell carcinoma (TCC). Thirty-eight patients underwent HALN, while 52 had an ON. End-points of comparison included operative time, estimated blood loss (EBL), intraoperative and postoperative complications, length of hospital stay, pathologic grade and stage of tumor, and tumor recurrence. RESULTS: The mean patient age was 72.3 and 70.6 years in the ON and HALN groups, respectively. Mean operative duration was 243 minutes (ON) and 244 minutes (HALN), with an EBL of 478mL in the open group versus 191 mL in the hand-assisted group (P<0.001). No intraoperative complications occurred, but postoperative complications occurred in 4% and 11% of the ON and HALN groups, respectively (P=0.21). The mean hospital duration was 7.1 days (ON) versus 4.6 days (HALN) (P<0.01). No difference existed in the pathologic grade or stage distribution of urothelial tumors between the 2 groups. The mean follow-up was 51.0 months in the ON group and 31.7 months in the HALN group. Recurrence of urothelial carcinoma occurred in 50% of patients who underwent ON and 40% treated by HALN (P=0.38) at a median interval of 9.1 and 7.7 months, respectively, after surgery. CONCLUSION: Hand-assisted laparoscopic nephroureterectomy is an effective modality for the treatment of upper urinary tract urothelial carcinoma. Patients benefited from less intraoperative blood loss and a shorter hospitalization with an equivalent intermediate-term oncologic outcome compared with that of the open approach. 相似文献
6.
7.
H Angus-Leppan GA Lambert J Michalicek 《Cephalalgia : an international journal of headache》1997,17(6):625-630
Co-existence of facial and occipital pain may occur in occipital neuralgia, migraine and cluster headache; suggesting convergence of trigeminal and cervical afferents. Such convergence has been shown in humans and other animals, but the site and extent of this are uncertain. In anaesthetized adult cats, the superior sagittal sinus and occipital nerve were stimulated electrically, and extracellular recordings made in the dorsolateral area of the upper cervical cord using glass-coated tungsten electrodes. Of 49 units in 10 cats, 33 (67%) had input from the superior sagittal sinus and the occipital nerve. Thirteen (27%) had superior sagittal sinus input and 3 (6%) had occipital nerve input. Convergent receptive fields were identified mechanically in 7 units. These experiments in cats show convergent input from occipital nerve and superior sagittal sinus on dorsolateral area units in two-thirds of cases studied. This experimental site of trigeminocervical convergence may relate to referral of pain in occipital neuralgia and other headaches. 相似文献
8.
In patients with PG-dependent renal function, NSAID administration
constantly reduces GFR and RBF in a dose-dependent fashion. In this
situation, the risk of overt acute renal failure is high and should be
taken into proper account. In contrast, the incidence of NSAID-related
renal structural alterations appears to be very low, yet the absolute
number of patients may be significant considering the wide use of such
drugs. Concerning the antiproteinuric effect of NSAIDs, the unfavourable
ratio risk/benefit does not seem to support their indication in proteinuric
nephropathies. The development of PGHS-2 selective inhibitors is promising,
and may open new therapeutical strategies in the treatment of the
progression of renal disease.
相似文献
9.
10.
Laparoscopic evaluation of tangential abdominal gunshot wounds. 总被引:3,自引:0,他引:3
The use of laparoscopy in abdominal trauma has been proposed for several decades; however, it has not been widely used. With the advent of laparoscopic cholecystectomy, general surgeons are realizing the potential of this technique. This should result in an expanded role for laparoscopy, including the evaluation of abdominal trauma. We present a series in which laparoscopy was used in the evaluation of tangential gunshot wounds to the abdomen. Laparoscopy enabled us to demonstrate whether the missile had violated the peritoneal cavity and to avoid laparotomy in cases without peritoneal penetration. 相似文献