全文获取类型
收费全文 | 1480564篇 |
免费 | 109975篇 |
国内免费 | 2112篇 |
专业分类
耳鼻咽喉 | 19087篇 |
儿科学 | 47690篇 |
妇产科学 | 39611篇 |
基础医学 | 220039篇 |
口腔科学 | 43955篇 |
临床医学 | 134989篇 |
内科学 | 293303篇 |
皮肤病学 | 31819篇 |
神经病学 | 121507篇 |
特种医学 | 54338篇 |
外国民族医学 | 296篇 |
外科学 | 205983篇 |
综合类 | 27368篇 |
现状与发展 | 4篇 |
一般理论 | 699篇 |
预防医学 | 129238篇 |
眼科学 | 32013篇 |
药学 | 105951篇 |
6篇 | |
中国医学 | 2790篇 |
肿瘤学 | 81965篇 |
出版年
2021年 | 13828篇 |
2019年 | 14163篇 |
2018年 | 19154篇 |
2017年 | 14709篇 |
2016年 | 15605篇 |
2015年 | 18073篇 |
2014年 | 24851篇 |
2013年 | 36223篇 |
2012年 | 51111篇 |
2011年 | 54201篇 |
2010年 | 30343篇 |
2009年 | 29045篇 |
2008年 | 49163篇 |
2007年 | 52414篇 |
2006年 | 51265篇 |
2005年 | 50414篇 |
2004年 | 47880篇 |
2003年 | 45497篇 |
2002年 | 42397篇 |
2001年 | 62018篇 |
2000年 | 63029篇 |
1999年 | 53488篇 |
1998年 | 15635篇 |
1997年 | 14061篇 |
1996年 | 14476篇 |
1995年 | 13471篇 |
1994年 | 12605篇 |
1992年 | 41798篇 |
1991年 | 40949篇 |
1990年 | 39565篇 |
1989年 | 38274篇 |
1988年 | 35424篇 |
1987年 | 34553篇 |
1986年 | 32905篇 |
1985年 | 31113篇 |
1984年 | 23649篇 |
1983年 | 20567篇 |
1982年 | 12181篇 |
1979年 | 22244篇 |
1978年 | 16222篇 |
1977年 | 13468篇 |
1976年 | 12421篇 |
1975年 | 13510篇 |
1974年 | 16315篇 |
1973年 | 16080篇 |
1972年 | 15148篇 |
1971年 | 14157篇 |
1970年 | 13375篇 |
1969年 | 12640篇 |
1968年 | 11823篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Multivitamin and alcohol intake and folate receptor alpha expression in ovarian cancer. 总被引:2,自引:0,他引:2
Linda E Kelemen Thomas A Sellers Gary L Keeney Wilma L Lingle 《Cancer epidemiology, biomarkers & prevention》2005,14(9):2168-2172
Folate receptor alpha (FRalpha) expression in epithelial ovarian cancer may be related to folate intake. We examined this association using multivitamin intake, a proxy for folic acid, and assessed whether the relation was modified by alcohol intake, a folate agonist. Cases (n = 148) with suspected epithelial ovarian cancer, of ages > or = 20 years, were seen at Mayo Clinic, Minnesota, between 2000 and 2004; those with tumor specimens (n = 108) were included in analyses. Outpatient controls (n = 148) without cancer and with at least one ovary intact were matched to cases by age (within 5 years) and state of residence. Multivitamin (> or = 4 pills/wk) and weekly alcohol (> or = 5 drinks) intakes were assessed. Tumor specimens were analyzed immunohistochemically for FRalpha. Multivariable rate ratios (RR) and 95% confidence intervals (CI) were estimated using unconditional logistic regression. In case-control analysis, the RRs of multivitamin intake with absent/weak/moderate and strong-expressing FRalpha tumors were 0.30 (95% CI, 0.12-0.70) and 0.47 (95% CI, 0.24-0.91), respectively. For alcohol, the associations were 0.84 (95% CI, 0.24-2.86) and 1.65 (95% CI, 0.69-3.93), respectively. In case-case analysis, the RR associated with developing strong-expressing versus other FRalpha tumors was 3.13 (95% CI, 1.14-8.65) for multivitamins and 1.58 (95% CI, 0.45-5.60) for alcohol. The data did not support evidence for an interaction between multivitamin and alcohol intake with risk of developing a strong-expressing FRalpha tumor. The association of multivitamin intake with ovarian cancer may depend on FRalpha expression level. 相似文献
992.
993.
Raymond E B Anakwe 《European journal of emergency medicine》2005,12(3):133-135
Traumatic aortic transection is an uncommon but often fatal injury. It is typically a high energy injury and may occur in the multiply injured patient. This injury is often missed. There is evidence that airbags and seat belts protect against these injuries. We present the case of a patient who survived. 相似文献
994.
995.
996.
997.
998.
P Codine E Barbotte F Denis-Laroque H Lansac T Dupetit F Pradies B Ricart C Herisson 《Annales de Réadaptation et de Médecine Physique》2005,48(8):598-602
OBJECTIVES: To determine the modification in postoperative D-dimer level as a function of the surgical act and to assess the relevance of this measure for diagnosing thromboembolism. METHOD: A cohort of 179 patients was followed: group 1 comprised 128 patients undergoing lower limb arthroplasty, group 2 comprised 29 patients undergoing lower limb surgery without implant, and group 3 comprised 22 patients undergoing spinal or upper limb surgery. D-dimer level was systematically measured on admission and then once a week for 4 weeks. Doppler ultrasonography was performed on clinical suspicion of deep vein thrombosis. D-dimer levels were compared between patients with and without deep vein thrombosis. RESULTS: D-dimer levels were constantly elevated postsurgery (2- to 6-fold above normal) and returned to normal by week 4 in groups 2 and 3 but remained elevated in group 1 (3-fold above normal). Deep vein thrombosis was suspected in 45 cases and confirmed by Doppler ultrasonography in 10 cases. D-dimer level was not significantly different between patients with deep vein thrombosis and those without. DISCUSSION AND CONCLUSIONS: In the postoperative period, measurement of D-dimer level does not aid in diagnosing thromboembolism since its constant high level obviates any negative predictive value. 相似文献
999.
LI-FERN HSU PIERRE JAÏS MÉLÈZE HOCINI PRASHANTHAN SANDERS MARTIN ROTTER YOSHIHIDE TAKAHASHI CHRISTOPHE SCAVÉE FREDERIC SACHER JACQUES CLÉMENTY MICHEL HAÏSSAGUERRE 《Pacing and clinical electrophysiology : PACE》2005,28(S1):S94-S98
The differentiation of pulmonary vein (PV) electrograms from atrial far-field signals during PV isolation (PVI) for atrial fibrillation (AF) may be difficult. In addition, owing to highly variable PV ostial sizes, current fixed-diameter circular PV mapping catheters may not yield optimal electrograms. We evaluated an expandable, circular 15–25 mm diameter, 20-pole mapping catheter for PV mapping during sustained AF in 25 patients. After selective PV angiography to define the ostial position and size, the catheter was introduced into each PV and withdrawn to the most stable proximal position, with optimal wall contact ensured by progressive loop expansion. At each PV ostium, electrograms recorded at high resolution (HR) were compared with those recorded at a resolution similar to that of a standard 10-pole Lasso catheter. After PVI performed during ongoing AF, the presence of residual far-field potentials (FFP) under both set-ups was compared. We mapped 97 PV, including 4 pairs with common ostia. In the HR recordings, the PV potentials had greater amplitude (0.5 ± 0.1 vs 0.3 ± 0.1 mV, P = 0.001) and fragmentation, whereas left atrial FFP were minimized. After successful isolation of all PV, FFP were observed in 33% of left superior and 28% of left inferior PV on the HR recordings, compared to 66% and 61%, respectively under normal resolution. Catheter stability and optimal wall contact, in combination with HR electrograms can optimize circumferential PV mapping during AF and improve the discrimination of FFP postablation. 相似文献
1000.
The influence of protein solubilisation, conformation and size on the burst release from poly(lactide-co-glycolide) microspheres. 总被引:5,自引:0,他引:5
Gayle Duncan Thomas J Jess Farahidah Mohamed Nicholas C Price Sharon M Kelly Christopher F van der Walle 《Journal of controlled release》2005,110(1):34-48
Encapsulation of proteins in poly(lactide-co-glycolide) microspheres via emulsion is known to cause insoluble protein aggregates. Following protein emulsification and encapsulation in PLGA microspheres, we used circular dichroism to show that the recoverable soluble protein fraction also suffers subtle conformational changes. For a panel of proteins selected on the basis of molecular size and structural class, conformational stability measured by chemical denaturation was not indicative of stability during emulsion-encapsulation. Partial loss of structure was observed for alpha-helical proteins released from freeze-dried microspheres in aqueous buffer, with dramatic loss of structure for a beta-sandwich protein. The addition of sucrose (a lyoprotectant) did not prevent the loss of protein conformation upon encapsulation. Therefore, the conformational changes seen for the released soluble protein fraction originates during emulsification rather than microsphere freeze-drying. Analysis of the burst release for all proteins in buffer containing denaturant or surfactant showed that the degree of protein solubilisation was the dominant factor in determining the initial rate and extent of release. Our data for protein release into increasing concentrations of denaturing buffer suggest that the emulsion-denatured protein fraction remains insoluble; this fraction may represent the protein loss encountered upon comparison of protein encapsulated versus protein released. 相似文献