全文获取类型
收费全文 | 1337篇 |
免费 | 105篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 45篇 |
妇产科学 | 14篇 |
基础医学 | 139篇 |
口腔科学 | 142篇 |
临床医学 | 132篇 |
内科学 | 241篇 |
皮肤病学 | 13篇 |
神经病学 | 31篇 |
特种医学 | 220篇 |
外科学 | 110篇 |
综合类 | 81篇 |
预防医学 | 83篇 |
眼科学 | 7篇 |
药学 | 79篇 |
中国医学 | 25篇 |
肿瘤学 | 72篇 |
出版年
2022年 | 13篇 |
2021年 | 10篇 |
2020年 | 8篇 |
2019年 | 10篇 |
2018年 | 29篇 |
2017年 | 21篇 |
2016年 | 21篇 |
2015年 | 24篇 |
2014年 | 47篇 |
2013年 | 77篇 |
2012年 | 67篇 |
2011年 | 60篇 |
2010年 | 61篇 |
2009年 | 47篇 |
2008年 | 49篇 |
2007年 | 73篇 |
2006年 | 26篇 |
2005年 | 31篇 |
2004年 | 24篇 |
2003年 | 13篇 |
2002年 | 20篇 |
2001年 | 22篇 |
2000年 | 26篇 |
1999年 | 31篇 |
1998年 | 62篇 |
1997年 | 53篇 |
1996年 | 43篇 |
1995年 | 31篇 |
1994年 | 32篇 |
1993年 | 29篇 |
1992年 | 29篇 |
1991年 | 32篇 |
1990年 | 30篇 |
1989年 | 33篇 |
1988年 | 41篇 |
1987年 | 32篇 |
1986年 | 23篇 |
1985年 | 35篇 |
1984年 | 12篇 |
1983年 | 19篇 |
1982年 | 12篇 |
1981年 | 10篇 |
1980年 | 10篇 |
1979年 | 12篇 |
1978年 | 11篇 |
1977年 | 9篇 |
1976年 | 11篇 |
1975年 | 8篇 |
1973年 | 3篇 |
1964年 | 2篇 |
排序方式: 共有1449条查询结果,搜索用时 31 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.
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
3.
Maria P. Panozzo Carlo Fabris Daniela Basso Giuseppe Del Favero Aldo Infantino Attilio Cecchetto Mario Plebani Remo Naccarato 《Clinical and experimental pharmacology & physiology》1993,20(3):185-191
1. The authors investigated the effect of two extrahepatic cholestasis models (one by bile duct ligation and the other by choledocho-jugular fistula) on the hepatic clearance of horseradish peroxidase in male Sprague-Dawley rats divided into four groups. 2. In groups A (n = 5 rats) and B (n = 5), bile duct ligation was performed, while a choledocho-jugular fistula was created in groups C (n = 5) and D (n= 7). A 10 mg intravenous bolus of horseradish peroxidase was injected after 24 h (groups A and C), 48 h (groups B and D) or 1 h (Group E; five sham-operated rats). Serum and bile samples were then serially collected for 2 h. 3. In all groups, serum horseradish peroxidase levels increased soon after injection and then rapidly decreased, the curves being similar. Biliary excretion increased for 30 min and then slowly decreased. The highest horseradish peroxidase biliary concentrations and outputs were found in Group B followed by Group A; both groups had significantly higher levels than Group E. No difference was found between horseradish peroxidase biliary excretion of groups C and D and that of sham-operated rats. 4. When each group was considered separately, sampling times correlated with the corresponding ratios of bile/ plasma HRP. Significant differences were found between the relative slopes of groups A, B and E, but not between those of groups C, D and E. 5. In conclusion, bile duct obstruction greatly affects the plasma-bile transfer of fluid phase markers, such as horseradish peroxidase, while single retention, caused by choledocho-jugular fistula, has no influence. The increased biliary hyperpressure related to the duration of cholestasis may account for the degree of horseradish peroxidase transfer which, in turn, probably depends on an enhanced paracellular passage. 相似文献
4.
Luigi La Vecchia Paolo Vincenzi Luca Favero Manuela Martini Andrea Rubboli Filippo Ottani Leonardo Varotto Alessandro Fontanelli 《Italian heart journal》2004,5(10):749-754
BACKGROUND: Recent studies evaluated the technique of direct coronary stenting as compared to stenting-after-predilation in selected anatomic and clinical settings. However, the impact of direct stenting in routine interventional practice remains poorly elucidated. METHODS: From April 1999 to March 2001, all percutaneous coronary interventions performed at our Center were prospectively analyzed to determine the frequency of direct stenting, the success rate and the variables associated with its utilization. RESULTS: 1151 lesions were treated in 835 procedures. Stenting was attempted in 835/1151 lesions (72.5%), 309 (37%) with direct stenting and 526 (63%) with stenting-after-predilation. Direct stenting was successful in 300/309 (97%) and stenting-after-predilation in 515/526 (98%). The success rate of direct stenting was significantly lower in small vessels (< or = 2.75 mm) (89.2 vs 98.5%, p = 0.005). Patients treated with direct stenting were younger (63 +/- 11 vs 65 +/- 11 years, p = 0.024). Direct stenting was preferentially used in saphenous vein grafts and at the ostium of the left anterior descending coronary artery, while it was avoided in bifurcation lesions and with increasing calcium burden. Operators with a caseload > 140 interventions per year were significantly more likely to perform direct stenting than less experienced operators (p = 0.017). In direct stenting, the total contrast medium and the fluoroscopy and procedural times were all significantly (p < 0.0001) lower than those observed in case of stenting-after-predilation. CONCLUSIONS: Direct coronary stenting is currently performed in about one third of the overall caseload. Variables pertaining to the operator's experience, lesion morphology and length, vessel size, and the clinical presentation are all important factors determining the selection of candidates suitable for direct stenting. 相似文献
5.
D A Pegues C M Beck-Sague S W Woollen B Greenspan S M Burns L A Bland M J Arduino M S Favero R C Mackow W R Jarvis 《Kidney international》1992,42(5):1232-1237
From July 18 through November 27, 1989, 12 anaphylactoid reactions (ARs) occurred in 10 patients at a hemodialysis center in Virginia. One patient required hospitalization; no patients died. ARs occurred within minutes of initiating dialysis and were characterized by peripheral numbness and tingling, laryngeal edema or angioedema, facial or generalized sensation of warmth, and/or nausea or vomiting. All 12 ARs occurred with dialyzers that had been reprocessed with an automated reprocessing system. A cohort study, including all patients undergoing dialysis sessions on the six days when an AR occurred, showed that the patients who experienced ARs were significantly more likely than patients who did not to be treated with angiotensin-converting enzyme (ACE) inhibitors (7/10 vs. 3/33; relative risk = 7.9; 95% confidence interval = 2.5 to 25.2) and to have been exposed to reused dialyzers rather than to new dialyzers (12/70 sessions vs. 0/31; P = 0.016). In those sessions using a reused dialyzer, the mean number of dialyzer uses in case-sessions was significantly higher than for noncase-sessions (10.3 vs. 6.2; P = 0.016). After reuse of dialyzers was discontinued at the center, no further ARs occurred, despite the continued administration of ACE inhibitors. This is the first report of an outbreak of ARs associated exclusively with reused dialyzers. We hypothesize that interactions between a dialyzer that has been repeatedly reprocessed and reused, blood, and additional factors, such as ACE inhibitors, increased the risk of developing ARs. 相似文献
6.
L S Belli L De Carlis E Del Favero G Civati B Brando F Romani P Aseni G F Rondinara B Palmieri A Meroni 《Transplantation proceedings》1988,20(5):861-864
ATN is a deleterious problem in the outcome of kidney transplantation. This complication is usually related to multiple factors including donor parameters, surgical technique, ischemic time, and recipient variables. In order to develop prophylactic measures, out of 430 kidney transplants performed in our Department, a series of 90 consecutive cadaveric renal allografts has been considered in this study. The overall incidence of IGNF was 23/90 (25.5%). Kidneys from MOD revealed a lower rate of IGNF (7/35 = 20%) when compared with organs from SOD (16/55 = 29%, P = NS). No difference was noted when kidneys were removed together with heart and/or liver and/or pancreas. Out of the donor factors, only CID was significant (17 +/- 9 hours in IGNF v 11 +/- 10 hours in patients with IGF, P = less than .05). Analysis of data concerning the fate of paired kidneys revealed two cases of IGNF in both kidneys from the same donor v 14 cases of IGNF in only one of the two paired grafts (P = NS). We conclude that: 1. Donor factors are clearly associated with a minority of IGNF. 2. The introduction of multiorgan procurement programs does not complicate early function. 3. Recipient factors (immunological events and intraoperative fluid management) provides important additive effects on initial graft nonfunction. 相似文献
7.
8.
Serum DU-PAN-2 in the differential diagnosis of pancreatic cancer: influence of jaundice and liver dysfunction 总被引:1,自引:0,他引:1
C Fabris A Malesci D Basso C Bonato G Del Favero M Tacconi T Meggiato P Fogar M P Panozzo C Ferrara 《British journal of cancer》1991,63(3):451-453
The usefulness of serum DU-PAN-2 in diagnosing pancreatic cancer and in distinguishing between this cancer and other benign and malignant diseases, and to assess the role of liver dysfunction in altering the serum levels of this marker were investigated. DU-PAN-2 was measured in the sera of 31 patients with pancreatic cancer, 32 with chronic pancreatitis, 20 with benign and 21 with malignant extra-pancreatic diseases. DU-PAN-2 was found to be above 300 U ml-1 in 21/31 patients with pancreatic cancer (sensitivity 68%). Only 3/32 patients with chronic pancreatitis had abnormal values. A substantial number of patients with both benign and malignant extra-pancreatic diseases had an elevated serum DU-PAN-2 (9/20 and 15/21, respectively). Correlations were found between DU-PAN-2 and (1) total bilirubin, (2) alanine-amino-transferase and (3) alkaline phosphatase. Of the patients with high DU-PAN-2 values, jaundice was found in: 2/3 with chronic pancreatitis, 9/10 with benign and 12/14 with malignant extra-pancreatic diseases. In conclusion, the serum DU-PAN-2 test for pancreatic malignancy is not completely satisfactory, because it is not sensitive enough. While the test for chronic pancreatitis has an acceptable specificity, the assay cannot distinguish between pancreatic cancer and other extra-pancreatic diseases, mainly of the liver and biliary tract. Liver dysfunction as well as jaundice seem to considerable affect the levels of this marker, as reported elsewhere for CA 19-9. 相似文献
9.
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
10.
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