首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   831篇
  免费   62篇
耳鼻咽喉   5篇
儿科学   19篇
妇产科学   13篇
基础医学   103篇
口腔科学   29篇
临床医学   72篇
内科学   176篇
皮肤病学   5篇
神经病学   70篇
特种医学   22篇
外科学   117篇
综合类   8篇
预防医学   89篇
眼科学   14篇
药学   106篇
肿瘤学   45篇
  2023年   10篇
  2021年   24篇
  2020年   16篇
  2019年   20篇
  2018年   19篇
  2017年   11篇
  2016年   16篇
  2015年   12篇
  2014年   14篇
  2013年   22篇
  2012年   36篇
  2011年   31篇
  2010年   15篇
  2009年   15篇
  2008年   53篇
  2007年   55篇
  2006年   38篇
  2005年   36篇
  2004年   37篇
  2003年   42篇
  2002年   37篇
  2001年   32篇
  2000年   27篇
  1999年   21篇
  1998年   10篇
  1997年   5篇
  1996年   16篇
  1995年   5篇
  1994年   10篇
  1993年   8篇
  1992年   14篇
  1991年   12篇
  1990年   8篇
  1989年   12篇
  1988年   17篇
  1987年   12篇
  1986年   10篇
  1985年   15篇
  1984年   11篇
  1983年   8篇
  1982年   5篇
  1979年   11篇
  1978年   8篇
  1977年   3篇
  1976年   4篇
  1975年   5篇
  1973年   8篇
  1972年   10篇
  1968年   3篇
  1967年   3篇
排序方式: 共有893条查询结果,搜索用时 156 毫秒
61.
Smit EE  Sra SK  Grabowski LR  Ward SL  Trocme SD 《Cornea》2003,22(4):332-337
PURPOSE: Recent research indicates that epithelial cells of the ocular surface can contribute to the allergic reaction by the release of inflammatory and/or chemotactic mediators. In this study, the role of two inflammatory mediators, previously identified in the tear film of ocular allergy subjects, TNF-alpha and IFN-gamma, were evaluated for their effect on the release of two chemotactic mediators, IL-8 and RANTES, from cultured human conjunctival epithelial cells. METHODS: Human conjunctival epithelial cells (primary cells or HC0597 cell line) were grown to confluence and stimulated with various concentrations of TNF-alpha, IFN-gamma, or a combination of both. Supernatants were collected at 6, 24, and 48 hours and stored frozen for subsequent ELISA analyses of RANTES and IL-8. RESULTS: RANTES and IL-8 release from HC0597 cells was stimulated in a dose- and time-dependent manner following treatment with TNF-alpha. However, only RANTES release was modulated by IFN-gamma treatment. Treatment of HC0597 cells with both TNF-alpha and IFN-gamma resulted in a synergistic increase in the release of RANTES. This synergistic effect was confirmed using primary cultures of human conjunctival epithelial cells. CONCLUSIONS: Stimulation of conjunctival epithelium with proinflammatory mediators, TNF-alpha and/or IFN-gamma, generated the release of the chemotactic factors IL-8 and RANTES, which could act to prolong inflammation. These two chemokines may prolong inflammation by recruiting eosinophils to the ocular surface. This is the first study to compare chemokine release in a cell line and primary cells; similar chemokine release after mediator stimulation was demonstrated, indicating that the two cell types are phenotypically similar.  相似文献   
62.
63.
The effect of diazepam on methadone self-administration was examined. Five methadone-maintained patients with a history of benzodiazepine abuse were recruited. Patients were stabilized on 80 mg of methadone per day. After stabilization patients participated in methadone self-administration sessions. During each session, 128 presses (fixed ratio 128) of 1 button delivered 10 ml of 0.054 mg/ml methadone solution. The same number of button presses on a 2nd button delivered 10 ml of vehicle. Forty-five min prior to the self-administration session, 0 (placebo), 5, 10, or 20 mg per 70 kg body weight diazepam was administered. Ratings of drug liking, goodness, strength, and high were collected 5, 30, 60, 90, and 150 min after the end of the self-administration session. Diazepam pretreatment significantly decreased the amount of methadone consumed. The 10- and 20-mg diazepam doses significantly increased reports of good, like, strong, and high.  相似文献   
64.
RATIONALE: Polydrug abuse is a problem that has been infrequently examined. In the present study, drug self-administration procedures were used to investigate the reinforcing effects of drug combinations. OBJECTIVES: To determine the absolute and relative response rates maintained by orally delivered methadone, cocaine, and their combinations under sequential and concurrent access. Choice between drug combinations containing different concentrations of cocaine was also determined. METHODS: Oral intake of methadone, cocaine, and their combinations was studied with rhesus monkeys during daily 3-h sessions. Lip contact (the operant response) was reinforced by delivery of liquid contingent upon completion of a fixed-ratio schedule. In one series, the drugs and drug combinations were studied sequentially with the water vehicle concurrently available. In the next series, the drugs and drug combinations were concurrently available. In the third series, pairs of drug combinations containing different concentrations of cocaine were also concurrently available. RESULTS: Methadone, cocaine and their combinations functioned as reinforcers. Under sequential access, response rates for the drug combinations and the component drugs were often similar. However, under concurrent access, response rates for the drug combinations were greater than response rates for the component drugs at the highest FR size for each condition. Also, drug combinations containing higher cocaine concentrations were preferred to combinations containing lower cocaine concentrations. CONCLUSIONS: Combinations of methadone and cocaine have relatively greater reinforcing effects than the component drugs, and these greater reinforcing effects are better detected with concurrent measures than with sequential measures.  相似文献   
65.
Acid beta-glucosidase (GCase) is the enzyme deficient in Gaucher disease, an inherited metabolic prototype for enzyme and gene therapy. An 80-kDa mammalian cytoplasmic protein (TCP80/NF90) was discovered to interact with the GCase mRNA coding region and inhibit its translation in vitro and ex vivo. Human TCP80/NF90 is identical to NF90, an IL-2 enhancer protein, and MPP4, an M-phase phosphoprotein. The interaction of recombinant TCP80/NF90 with GCase mRNA was evaluated using the baculovirus/Sf9 insect cell system since these cells lack this protein. Purified recombinant and isolated mammalian cytoplasmic TCP80/NF90 had identical functions including binding of coding regions of selected RNAs and inhibition of their in vitro translation. Individual baculoviruses containing the human TCP80/NF90 cDNA (vSf9/TCP80) and GCase cDNA (vSf9/GCase) were used to co-infect Sf9 cells. The presence of preformed TCP80/NF90 significantly (>87%) inhibited wild-type GCase mRNA translation in these cells, but baculovirus containing a mutant GCase did not. Sf9 cells co-infected with vSf9/TCP80 showed a major reduction of GCase RNA polysome association. These results show that the multifunctional protein, TCP80/NF90, can function in vivo as a translation inhibitory protein and include alterations of mRNA binding to polysomes as a component of its mechanism of action.  相似文献   
66.
Seven eyes containing a copper foreign body for a period from 8 months to 2.5 years were studied histopathologically. Foreign bodies, containing 99% copper, were in all eyes, encapsulated and located in the anterior vitreous. Characteristic features were: formation of foreign body granuloma, especially in later stages, marked fibroblastic proliferation in the vitreous with traction retinal detachment, choroidal effusion with fibrosis and foci of chronic nongranulomatous inflammation in cyclitic membranes, iris, ciliary body and sclera. Copper could be identified by rubeanic acid and rhodanine stainings in the fibrous capsule around foreign body in all eyes, in the lens capsule in one eye and in macrophages in the vitreous and retina in 2 eyes. In eyes with intravitreal haemorrhage macrophages contained also haemosiderin.  相似文献   
67.
Long-term patency of coronary artery bypass grafts (CABG) with internal mammary artery (IMA) is better than with saphenous vein (SV) grafts. To determine if vascular prostacyclin (PGI2) produced by IMA might contribute to the improved outcome, we compared PGI2 generated by IMA and SV fragments from 26 patients undergoing CABG and tested the effect of preoperative, long-term ingestion of of aspirin. Fresh tissues were incubated in buffer +/- 25 mumol/L of sodium arachidonate at 37 degrees C for 5 minutes to stimulate PGI2 production, measured by radioimmunoassay of its major hydrolytic product, 6-keto-PGF1 alpha. Results were expressed in picograms of 6-keto-PGF1 alpha per milligram tissue wet weight for total PGI2 production by vascular segments and picograms per cm2 surface area for endothelial PGI2 production. Endothelial PGI2 production was compared for IMA and SV in template-stirring chambers that exposed only the luminal surface of the vessel, excluding underlying smooth muscle. Endothelial PGI2 production by IMA was significantly higher than production by SV under both basal (mechanical stimulation only 1436 +/- 224 versus 842 +/- 227 pg/cm2, mean +/- SEM, p greater than 0.05) and stimulated (25 mumol/L sodium arachidonate: 3343 +/- 347 versus 2032 +/- 465 pg/cm2, p less than 0.025) conditions in patients not receiving aspirin. For patients receiving aspirin, endothelial PGI2 production by IMA was significantly higher than production by SV in stimulated conditions (1382 +/- 526 versus 683 +/- 124 pg/cm2, p less than 0.05). Histologic examination of the tissue segments revealed intact endothelium after incubation in both IMA and SV. Thus a high capacity for PGI2 synthesis and diminished inhibition of PGI2 after aspirin were demonstrated for IMA compared with SV tissue and may be a factor in the improved patency of IMA grafts.  相似文献   
68.
Survival and cell mediated immunity after burn injury in aged mice   总被引:1,自引:0,他引:1  
The elderly are less able to survive burn injury than young healthy individuals. Regardless of age, burn victims often succumb to secondary infections rather than the primary injury. Since immune responses diminish with age, it is likely that aged individuals are predisposed to a poor outcome by virtue of their weak immune system. Elevated production of macrophage-derived mediators, including interleukin-6 (IL-6), may lead to post-injury immunosuppression in young adults. Healthy aged individuals produce high circulating levels of these mediators; therefore, the combination of the age and burn trauma could further suppress immune responses and contribute to the rapid demise of aged burn patients. Herein, the effects of age and burn trauma using a murine scald injury model were examined. After injury, aged mice are less likely to survive, are unable to mount immune responses, and produce more IL-6 when compared to young adult mice given the same size injuries. Enhancing our understanding of the mechanisms responsible for regulating cell-mediated immune responses after injury could lead to the development of therapies designed to treat aged burn patients.  相似文献   
69.
Adriamycin (ADR)-resistant sublines of B16-BL6 mouse melanoma selected by exposure to increasing concentrations of ADR were characterized in vitro for growth properties and in vivo for tumorigenicity and pulmonary metastases. The progressively resistant sublines adapted to grow in the presence of 0.025, 0.05, 0.1, and 0.25 microgram/ml ADR in monolayer culture were found to be 5-, 10-, 20-, and 40-fold ADR-resistant, respectively, compared to the parental sensitive cells, using a soft-agar colony assay and continuous ADR treatment for 7 days. The doubling time in monolayer culture of the parent sensitive and progressively ADR-resistant sublines of B16-BL6 melanoma cells was approximately 16-18 h. Although the colony-forming efficiency in soft agar of parental sensitive cells was only 0.5-4%, the 5-, 10-, 20-, and 40-fold ADR-resistant sublines had colony-forming efficiencies of 15, 20, 30, and 77%, respectively. Tumorigenicity in C57BL/6 mice of progressively ADR-resistant sublines was similar to parental sensitive cells following s.c. and i.p. implantation of 10(5)-10(6) tumor cells. Experimental pulmonary metastases were significantly lower in ADR-resistant sublines with progressive resistance. Additionally, unlike the parental sensitive and 5-fold ADR-resistant B16-BL6 cells, the 10-, 20-, and 40-fold ADR-resistant sublines were spontaneously nonmetastatic. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunochemical detection of P-glycoprotein revealed the presence of a Mr 170,000 plasma membrane glycoprotein in the 40-fold ADR-resistant subline and its counterpart maintained for 1 year in ADR-free medium. Results from this study suggest that progressively ADR-resistant B16-BL6 mouse melanoma cells selected in vitro demonstrate a marked increase in colony formation in soft agar and a decrease in the ability to produce pulmonary metastases, without alterations in tumorigenicity.  相似文献   
70.
By means of examination for caries-morbidity and the degree of treatment by patients with cleft lip and palate will be referred to the inadequate care of this patients. Longitudinal studies show the sequences of caries and extractions for the development of dentition. As a result of this will be decuced demands for the dentistry for children of patients with cleft lip and palate.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号