全文获取类型
收费全文 | 24922篇 |
免费 | 1987篇 |
国内免费 | 49篇 |
专业分类
耳鼻咽喉 | 233篇 |
儿科学 | 750篇 |
妇产科学 | 629篇 |
基础医学 | 3291篇 |
口腔科学 | 630篇 |
临床医学 | 3391篇 |
内科学 | 4658篇 |
皮肤病学 | 376篇 |
神经病学 | 2350篇 |
特种医学 | 756篇 |
外科学 | 2937篇 |
综合类 | 375篇 |
一般理论 | 22篇 |
预防医学 | 3008篇 |
眼科学 | 458篇 |
药学 | 1622篇 |
1篇 | |
中国医学 | 35篇 |
肿瘤学 | 1436篇 |
出版年
2023年 | 122篇 |
2022年 | 208篇 |
2021年 | 465篇 |
2020年 | 304篇 |
2019年 | 460篇 |
2018年 | 577篇 |
2017年 | 417篇 |
2016年 | 504篇 |
2015年 | 516篇 |
2014年 | 730篇 |
2013年 | 1067篇 |
2012年 | 1534篇 |
2011年 | 1579篇 |
2010年 | 878篇 |
2009年 | 867篇 |
2008年 | 1410篇 |
2007年 | 1468篇 |
2006年 | 1473篇 |
2005年 | 1334篇 |
2004年 | 1263篇 |
2003年 | 1073篇 |
2002年 | 1054篇 |
2001年 | 566篇 |
2000年 | 524篇 |
1999年 | 481篇 |
1998年 | 247篇 |
1997年 | 220篇 |
1996年 | 176篇 |
1995年 | 186篇 |
1994年 | 160篇 |
1993年 | 150篇 |
1992年 | 313篇 |
1991年 | 307篇 |
1990年 | 348篇 |
1989年 | 301篇 |
1988年 | 260篇 |
1987年 | 247篇 |
1986年 | 254篇 |
1985年 | 241篇 |
1984年 | 214篇 |
1983年 | 182篇 |
1982年 | 138篇 |
1981年 | 119篇 |
1980年 | 123篇 |
1979年 | 172篇 |
1978年 | 138篇 |
1977年 | 129篇 |
1976年 | 137篇 |
1974年 | 130篇 |
1972年 | 124篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
The flow cytometric crossmatch and early renal transplant loss 总被引:3,自引:0,他引:3
R J Mahoney K A Ault S R Given R J Adams A C Breggia P A Paris G E Palomaki S A Hitchcox B W White J Himmelfarb 《Transplantation》1990,49(3):527-535
Data from this retrospective study indicate that a positive two-color T and/or B cell flow cytometric crossmatch (FCXM) is predictive of early renal allograft loss (less than 2 months) in cadaveric kidney donor recipients who had a negative crossmatch by the antihuman globulin complement-dependent cytotoxicity technique. Among 90 cadaveric kidney donor recipients (67 primary, 23 regrafts), 14 (8 primary, 6 regrafts) lost their renal allografts within 2 months, and 10 of the 14 were FCXM positive and HLA sensitized. The remaining 76 allografts survived beyond 2 months, 12 of which were FCXM-positive. Thus, the FCXM sensitivity rate for detecting early graft loss was 71%, and the specificity rate was 84%. Cadaveric graft-loss rates at 2 months were 33% for primary and 60% for FCXM-positive regrafts in contrast to 7% for primary and 0% for FCXM-negative regrafts. The difference in early graft loss between FCXM-positive and FCXM-negative recipients was statistically significant (P less than 0.0001). Subset analyses of FCXM-positive graft recipients indicate: (1) previous early graft loss contraindicates transplantation of an FXCM-positive regraft (P = 0.03); and (2) panel reactive antibody (PRA) less than or equal to 10% at crossmatch is not associated with early graft loss (P = 0.04). There was no significant difference in 1-year graft survival between primary and regrafts in either FCXM-negative recipients (85% vs. 77%, respectively) or FCXM-positive recipients (67% vs. 40%). All 12 of the FCXM-positive primary and regrafts that survived 2 months continued to function at 2 years. Stepwise logistic regression analysis of 5 independent predictor variables (FCXM status, gender, primary vs. regraft status, PRA level, and HLA mismatched antigens) indicated that the FCXM test was the best predictor of early graft loss. When FCXM results of the 90 cadaveric graft recipients were ranked in three groups, an FCXM channel shift of 29 or greater (third tertile) on a 1024 channel log scale was associated with a 7.0-fold (95% confidence interval 1.9-25.5) increased risk of early graft failure when compared to the first two tertiles. These data indicate that the FCXM offers an additional approach for identifying sensitized patients at risk of early renal allograft loss. 相似文献
22.
Denise Haderski Sergey Nazarenko Chih-Min Cheng Anne Hiltner Eric Baer 《Macromolecular chemistry and physics.》1995,196(8):2545-2561
The crystallization behavior of coextruded microlayered sheets comprised of 657 alternating layers of polycarbonate (PC) and a miscible copolyester of mainly 1,4-cyclohexanedimethanol and terephthalic acid (KODAR) was investigated as a function of annealing time when the KODAR was crystallized isothermally from the glass at 195°C. Comparisons were made with crystallization of KODAR alone, and with crystallization of KODAR from melt blends with PC. The kinetics of crystallization and the morphology of the crystallized KODAR were characterized with differential scanning calorimetry, and by examination of thin sections microtomed from annealed specimens in the polarized light microscope and the transmission electron microscope. The growth rate of small, birefringent KODAR spherulites was non-linear, and was strongly affected by diffusion of PC into the KODAR layers. Diffusion of amorphous PC into the KODAR layers retarded nucleation and spherulite growth and decreased spherulite density. The effect became more pronounced as the KODAR layer thickness was reduced. Spherulities nucleated randomly throughout the KODAR layers in the PC/KODAR 20/80 (w/w) microlayer and grew rapidly to form a continuous layer of impinged spherulites. In contrast, spherulites in the PC/KODAR 40/60 and 60/40 microlayers nucleated and grew along the center of the KODAR layers where the KODAR concentration was highest. 相似文献
23.
24.
25.
Previous work has reported that the 5-hydroxytryptamine (5-HT)1A agonist, 8-hydroxy 2-(di-n-propylamino)tetralin (8-OH DPAT), reduces ethanol intake by rats. However, as 8-OH DPAT reduces 5-HT neurotransmission, these findings are inconsistent with the proposed inhibitory role of central 5-HT neurons on ethanol intake. We examined the effect of 8-OH DPAT on ethanol, water and food intake in rats maintained on a limited access schedule using a lower dose range (6–250 µg/kg) and by assessing concomitant changes in behaviour. Low doses of 8-OH DPAT enhanced ethanol intake even when food and water were offered as alternatives. Suppression in ethanol intake was observed at higher doses where elements of the 5-HT syndrome were apparent. Similar observations were made in both fluid and non-fluid deprived water drinking rats, suggesting the latter effect is non-selective. Therefore 8-OH DPAT may both increase or decrease ethanol consumption in the rat depending on the dose used. 相似文献
26.
27.
Cyclosporine A inhibition of microcystin toxins 总被引:2,自引:0,他引:2
Cyclosporine A (CyA) given i.v. at a dose of 1.25 mg/mouse blocks a subsequent i.v. lethal dose (1.7-1.8 x LD50) of microcystin-LR for 24 hr, and is about 50% protective at 48 hr. Conversely, the fraction of mice that can be rescued by CyA (0.2 mg/mouse) after a lethal dose of microcystin-LR decreases rapidly with a pharmacodynamic half-time of only about 100 sec. The prophylactic action of CyA was tested against lethal doses of four microcystins. The acute lethality of 1.7-1.8 x LD50 dose of microcystin-LR, -RR, -LY, or -LA given 1 hr after administration of 0.2 mg of CyA is 0%, 0%, 58%, or 100%, respectively. Even a 0.6 mg/mouse dose of CyA is ineffective prophylaxis against a lethal dose of microcystin-LA. The inhibitory potency of CyA on microcystin toxicity can be completely reversed by the single L-amino acid substitution of alanine for arginine in the microcystin. 相似文献
28.
We describe a prospective, long-term evaluation of the Schultz metacarpophalangeal joint implant. The prosthesis is a semiconstrained, cemented implant with a ball-in-socket articulation. Thirty-six implants were followed for an average of 10.9 years. There was a progressive decrease in range of motion and strength and a recurrence of ulnar deviation. The neck of the proximal phalangeal component fractured in 39% of the joints. Periarticular heterotopic bone formed in all joints, but was extensive in only 22%. Although some lucency of the bone-cement interface was seen in 80% of the joints, no prosthetic loosening occurred in this series. Our results indicate that long-term, intramedullary cement fixation of relatively long-stemmed components can be satisfactory. However, the articulated portion of this implant does not consistently withstand the stresses transmitted across the joint and does not provide long-term joint stability. 相似文献
29.
Denise M Connor Shawn Binkley Neil O Fishman Leanne B Gasink Darren Linkin Ebbing Lautenbach 《Infection control and hospital epidemiology》2007,28(12):1408-1410
We examined the possible unintended consequences of a 72-hour automatic order to discontinue vancomycin therapy in an antimicrobial stewardship program (ASP). Of 120 patients, 11 had vancomycin therapy discontinued at 72 hours without a call to the ASP, and 7 experienced a treatment interruption of 6-36 hours. All discontinuation of therapy was considered appropriate, and the 7 treatment interruptions did not have clear clinical consequences. Only one-third of patients had ASP stickers that warned of impending discontinuation of vancomycin therapy placed appropriately in the medical record. 相似文献
30.
In a single-blind, controlled, prospective trial of 242 sutured wounds of the hand in the A&E department there was increased late purulent infection in those treated without gloves. This difference is statistically significant. We recommend wearing of sterile gloves to suture all wounds in A&E departments. 相似文献