全文获取类型
收费全文 | 162092篇 |
免费 | 10709篇 |
国内免费 | 804篇 |
专业分类
耳鼻咽喉 | 1601篇 |
儿科学 | 4192篇 |
妇产科学 | 2948篇 |
基础医学 | 21823篇 |
口腔科学 | 3666篇 |
临床医学 | 15564篇 |
内科学 | 35005篇 |
皮肤病学 | 3052篇 |
神经病学 | 15629篇 |
特种医学 | 6519篇 |
外国民族医学 | 7篇 |
外科学 | 24332篇 |
综合类 | 1997篇 |
现状与发展 | 2篇 |
一般理论 | 142篇 |
预防医学 | 11678篇 |
眼科学 | 3353篇 |
药学 | 11087篇 |
3篇 | |
中国医学 | 250篇 |
肿瘤学 | 10755篇 |
出版年
2023年 | 837篇 |
2022年 | 1273篇 |
2021年 | 2901篇 |
2020年 | 2021篇 |
2019年 | 2906篇 |
2018年 | 3522篇 |
2017年 | 2752篇 |
2016年 | 3145篇 |
2015年 | 3634篇 |
2014年 | 5189篇 |
2013年 | 7057篇 |
2012年 | 10874篇 |
2011年 | 11470篇 |
2010年 | 6548篇 |
2009年 | 6237篇 |
2008年 | 10515篇 |
2007年 | 11244篇 |
2006年 | 10729篇 |
2005年 | 10956篇 |
2004年 | 10380篇 |
2003年 | 9811篇 |
2002年 | 9194篇 |
2001年 | 1831篇 |
2000年 | 1443篇 |
1999年 | 1889篇 |
1998年 | 2200篇 |
1997年 | 1733篇 |
1996年 | 1488篇 |
1995年 | 1363篇 |
1994年 | 1198篇 |
1993年 | 1182篇 |
1992年 | 991篇 |
1991年 | 992篇 |
1990年 | 804篇 |
1989年 | 840篇 |
1988年 | 746篇 |
1987年 | 755篇 |
1986年 | 697篇 |
1985年 | 726篇 |
1984年 | 764篇 |
1983年 | 712篇 |
1982年 | 844篇 |
1981年 | 781篇 |
1980年 | 680篇 |
1979年 | 515篇 |
1978年 | 469篇 |
1977年 | 478篇 |
1976年 | 418篇 |
1975年 | 369篇 |
1974年 | 337篇 |
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
981.
Nicholas Thatcher Wendi Qian Peter I Clark Penelope Hopwood Robert J Sambrook Robert Owens Richard J Stephens David J Girling 《Journal of clinical oncology》2005,23(33):8371-8379
PURPOSE: Ifosfamide, carboplatin, etoposide, and vincristine, alone and in combination, are highly active against small-cell lung cancer (SCLC). This trial was designed to investigate whether survival could be improved by a regimen of all four drugs (ICE-V) compared with standard chemotherapy in patients with SCLC and good performance status, and to assess the patients' quality of life (QL). PATIENTS AND METHODS: Patients were randomly assigned to receive six cycles of either ICE-V at 4-week intervals without dose reduction or standard chemotherapy administered according to local practice. The recommended standard control regimens were cyclophosphamide, doxorubicin, and etoposide; and cisplatin and etoposide. RESULTS: A total of 402 patients were randomly assigned, and 350 (87%) patients have died. Overall survival was longer in the ICE-V group (hazard ratio, 0.74; 95% CI, 0.60 to 0.91; P = .0049), median survival was 15.6 months in the ICE-V group and 11.6 months in the control group, and 2-year survival rates were 20% and 11%, respectively. There was no evidence that the relative survival benefit for ICE-V was less in extensive-stage than in limited-stage patients. An increased rate of septicemia was reported in the ICE-V group (15% v 7% in the control group), but this did not result in an increase in reported treatment-related deaths (four patients [2%] in both groups). The findings on QL were broadly similar in both groups, with some benefit in favor of ICE-V. CONCLUSION: Compared with standard chemotherapy, the ICE-V regimen improves overall survival without QL penalties, despite an increased but manageable level of toxicity. 相似文献
982.
Morgan C. Willson Emily C. Bell Sanjay Dave Sheila J. Asghar Brent M. McGrath Peter H. Silverstone 《European neuropsychopharmacology》2005,15(6):633-639
Dextroamphetamine administration in healthy controls produces a range of subjective and physiological effects, which have been likened to those occurring during mania. However, it is uncertain if these can be attenuated by lithium since conflicting results have been reported. To date there have been no previous studies examining the effects of valproate on dextroamphetamine-induced mood and physiological changes. The current study was a double-blind, placebo-controlled, study in which volunteers received either 1000 mg sodium valproate (n = 12), 900 mg lithium (n = 9), or placebo (n = 12) pre-treatment for 14 days. Subjective and physiological measures were then obtained prior to administration of a 25 mg dose of dextroamphetamine, and at two time points after administration. Differences in the response to dextroamphetamine were assessed between the three treatment groups. The results of this study show that pre-treatment with lithium only significantly attenuated dextroamphetamine-induced change in happiness, while valproate pre-treatment significantly attenuated the effects of dextroamphetamine on happiness, energy, alertness and on the diastolic blood pressure. These results suggest that lithium and valproate do not have the same mechanism of action on dextroamphetamine-induced changes, and this finding may relate to differences in their mechanism of action in mood disorders. 相似文献
983.
Wilbert H M Heijne Angela L Slitt Peter J van Bladeren John P Groten Curtis D Klaassen Rob H Stierum Ben van Ommen 《Toxicological sciences》2004,79(2):411-422
Rats were exposed to three levels of bromobenzene, sampled at 6, 24, and 48 h, and liver gene expression profiles were determined to identify dose and time-related changes. Expression of many genes changed transiently, and dependent on the dose. Few changes were identified after 6 h, but many genes were differentially expressed after 24 h, while after 48 h, only the high dose elicited large effects. Differentially expressed genes were involved in drug metabolism (upregulated GSTs, mEH, NQO1, Mrps, downregulated CYPs, sulfotransferases), oxidative stress (induced HO-1, peroxiredoxin, ferritin), GSH depletion (induced GCS-l, GSTA, GSTM) the acute phase response, and in processes like cholesterol, fatty acid and protein metabolism, and intracellular signaling. Trancriptional regulation via the electrophile and sterol response elements seemed to mediate part of the response to bromobenzene. Recovery of the liver was suggested in response to BB by the altered expression of genes involved in protein synthesis and cytoskeleton rearrangement. Furthermore, after 48 h, rats in the mid dose group showed no toxicity, and gene expression patterns resembled the normal situation. For certain genes (e.g., CYP4A, metallothioneins), intraday variation in expression levels was found, regardless of the treatment. Selected cDNA microarray measurements were confirmed using the specific and sensitive branched DNA signal amplification assay. 相似文献
984.
The role of positron emission tomography in the discovery and development of new drugs; as studied in laboratory animals. 总被引:3,自引:0,他引:3
Peter Roselt Steven Meikle Michael Kassiou 《European journal of drug metabolism and pharmacokinetics》2004,29(1):1-6
Drug discovery and development is time consuming and a costly procedure. The challenges for the pharmaceutical industry range from the evaluation of potential new drug candidates, the determination of drug pharmacokinetics/pharmacodynamics, the measurement of receptor occupancy as a determinant of drug efficacy, and the pharmacological characterisation of mechanisms of action. Positron emission tomography (PET) is a powerful quantitative imaging technique for looking at biochemical pathways, molecular interactions, drug pharmacokinetics and pharmacodynamics. Recent advances in emission tomography, particularly the development of small animal PET scanners, image reconstruction and animal models of disease have led to the development of extremely sensitive and specific tools for imaging biochemical processes in vivo, therefore representing a new means of providing information for drug development and evaluation. Many human genes have a related mouse gene, allowing mice to be used as a platform for mimicking human disease, using knock-out and knock-in gene technology. Consequently PET imaging of rodents is emerging as a cost effective means of screening new pharmaceuticals and decreasing the time required for new drug development. 相似文献
985.
Kurt B Stevenson Matthew Samore James Barbera Elizabeth Hannah James W Moore Julie L Gerberding Peter Houck 《American journal of health-system pharmacy》2004,61(8):787-792
PURPOSE: Pharmacist involvement in antimicrobial use at small rural hospitals in four Western states was studied. METHODS: Surveys were mailed in July 2000 to hospitals with a daily patient census of <150 in Idaho, Nevada, Utah, and eastern Washington. RESULTS: Seventy-seven (77%) of 100 hospitals returned completed surveys. Only 5% of the hospitals had onsite pharmacists 24 hours per day. An onsite pharmacist was present for a median of 26 hours per week in hospitals without 24-hour pharmacist coverage (range, 0-116 hr/wk). Many hospitals (71%) had policies for monitoring or controlling antimicrobial use, but only 28% had a system capable of monitoring compliance with such policies. Few hospitals had systems for recommending changes in antimicrobial selection on the basis of susceptibility test results (27%) or for monitoring physician compliance with dosage recommendations by pharmacists (21%). Onsite pharmacist hours were significantly associated with pharmacists being involved in the initial ordering of antibiotics and providing active oversight of antimicrobial use. There was a negative correlation between onsite pharmacist hours and use of third-generation cephalosporins and carbapenems. CONCLUSION: A survey showed that rural hospital pharmacists in four Western states spent relatively little time monitoring and influencing antimicrobial prescribing. 相似文献
986.
Alison E M Vickers Muriel Saulnier Elba Cruz Marjolijn T Merema Kristine Rose Philip Bentley Peter Olinga 《Toxicological sciences》2004,82(2):534-544
Liver slice viability is extended to 96 h for rat, expanding the use of this in vitro model for studying mechanisms of injury and repair, including pathways of fibrosis. The contributing factors to increased organ slice survival consist of the use of a preservation solution for liver perfusion and slice preparation, obtaining rats that are within the weight range of 250-325 g, placing a cellulose filter atop the titanium mesh roller-insert to support the slice, and maintaining the slices in an optimized culture medium which is replaced daily. The liver slices remain metabolically active, synthesizing adenosine triphosphate (ATP), glutathione, and glycogen, and exhibit preserved organelle integrity and slice morphology. Slice preparation results in 2-cut surfaces which likely triggers a repair and regenerative response. The fibrogenic pathways are evident by the activation of stellate cells, the proliferation of myofibroblast-like cells, and an increased collagen deposition by 48 h. Markers indicative of activated stellate cells, alpha-smooth muscle actin, collagen 1a1, desmin, and HSP47 are substantiated by real time-PCR. Increased staining of alpha-smooth muscle actin initially around the vessels and by 72-96 h in the tissue is accompanied by increased collagen staining. Microarray gene expression revealed extracellular matrix changes with the up-regulation of cytoskeleton, filaments, collagens, and actin genes; and the down-regulation of genes linked with lipid metabolism. The improvements in extending liver slice survival, in conjunction with its three-dimensional multi-cellular complexity, increases the application of this in vitro model for investigating pathways of injury and repair, and fibrosis. 相似文献
987.
988.
989.
990.