全文获取类型
收费全文 | 13519篇 |
免费 | 1547篇 |
国内免费 | 34篇 |
专业分类
耳鼻咽喉 | 243篇 |
儿科学 | 414篇 |
妇产科学 | 303篇 |
基础医学 | 2109篇 |
口腔科学 | 222篇 |
临床医学 | 1796篇 |
内科学 | 2830篇 |
皮肤病学 | 168篇 |
神经病学 | 885篇 |
特种医学 | 412篇 |
外科学 | 1735篇 |
综合类 | 297篇 |
一般理论 | 12篇 |
预防医学 | 1529篇 |
眼科学 | 157篇 |
药学 | 1088篇 |
中国医学 | 4篇 |
肿瘤学 | 896篇 |
出版年
2022年 | 101篇 |
2021年 | 194篇 |
2020年 | 125篇 |
2019年 | 197篇 |
2018年 | 224篇 |
2017年 | 193篇 |
2016年 | 186篇 |
2015年 | 211篇 |
2014年 | 284篇 |
2013年 | 435篇 |
2012年 | 628篇 |
2011年 | 648篇 |
2010年 | 320篇 |
2009年 | 298篇 |
2008年 | 532篇 |
2007年 | 637篇 |
2006年 | 577篇 |
2005年 | 589篇 |
2004年 | 570篇 |
2003年 | 588篇 |
2002年 | 519篇 |
2001年 | 471篇 |
2000年 | 521篇 |
1999年 | 450篇 |
1998年 | 174篇 |
1997年 | 172篇 |
1996年 | 142篇 |
1995年 | 152篇 |
1994年 | 135篇 |
1993年 | 119篇 |
1992年 | 354篇 |
1991年 | 337篇 |
1990年 | 329篇 |
1989年 | 328篇 |
1988年 | 275篇 |
1987年 | 276篇 |
1986年 | 252篇 |
1985年 | 260篇 |
1984年 | 175篇 |
1983年 | 150篇 |
1982年 | 122篇 |
1981年 | 97篇 |
1980年 | 97篇 |
1979年 | 205篇 |
1978年 | 136篇 |
1977年 | 104篇 |
1976年 | 100篇 |
1974年 | 111篇 |
1973年 | 100篇 |
1972年 | 101篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
P J Hayden C J Welsh Y Yang W H Schaefer A J Ward J L Stevens 《Chemical research in toxicology》1992,5(2):232-237
Nephrotoxic cysteine conjugates derived from a variety of halogenated alkenes are enzymatically activated via the beta-lyase pathway to yield reactive sulfur-containing metabolites which bind covalently to cellular macromolecules. Mitochondria contain beta-lyase enzymes and are primary targets for binding and toxicity. Previously, mitochondrial protein and/or DNA have been considered as molecular targets for cysteine conjugate metabolite binding. We now report that metabolites of nephrotoxic cysteine conjugates form covalent adducts with rat kidney mitochondrial phospholipids. Rat kidney mitochondria were incubated with the 35S-labeled conjugates S-(1,1,2,2-tetrafluoroethyl)-L-cysteine (TFEC), S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine (CTFC), S-(1,2-dichlorovinyl)-L-cysteine, and S-(1,2,3,4,4-pentachlorobutadienyl)-L-cysteine. Quantitation of metabolite binding to whole mitochondria and to mitochondrial protein and lipid fractions revealed that as much as 42% of the 35S-label associated with the mitochondria was found in the lipid fraction. Total lipids were also extracted from 35S-treated mitochondria and separated by thin-layer chromatography. 35S-Containing metabolites were found in the lipid fractions from mitochondria treated with each of the conjugates. Lipids from both [35S]CTFC- and [35S]-TFEC-treated mitochondria contained major 35S-labeled lipid adducts which had similar mobility by thin-layer chromatography. Fatty acid analysis, 19F and 31P NMR spectroscopy, and mass spectrometric analyses confirmed that the major TFEC and CTFC adducts are thioamides of phosphatidylethanolamine. 相似文献
4.
Rats were killed after 6 weeks of continuous ingestion of the pneumotoxic alkaloid monocrotaline (2.2 mg/kg/day), the neutrophil elastase inhibitor SC39026 (60 mg/kg/day), or both. Pulmonary reactions were evaluated by light and electron microscopy. Lung endothelial function was monitored by angiotensin converting enzyme (ACE) activity, plasminogen activator (PLA) activity, and prostacyclin (PGI2) and thromboxane (TXA2) production. Lung hydroxyproline content was measured as an index of interstitial fibrosis. Cardiac right ventricular hypertrophy was determined by the right ventricle to the left ventricle plus septum weight ratio (RV/LV + S). Rats receiving SC39026 alone did not differ significantly from untreated control animals with respect to any of the quantitative endpoints, although rarefaction of Type I pneumocytes was observed in the electron micrographs of these animals. Monocrotaline-treated rats, in contrast, developed a significant increase in RV/LV + S, and exhibited pulmonary edema, inflammation, fibrosis, and muscularization and occlusive mural thickening of the pulmonary small arteries and arterioles. These monocrotaline-induced structural changes were accompanied by decreased lung ACE and PLA activities, and increased PGI2 and TXA2 production, and by an increase in lung hydroxyproline content. Cotreatment with SC39026 ameliorated the monocrotaline-induced pulmonary vascular wall thickening and the cardiac right ventricular hypertrophy. These data suggest that inappropriate neutrophil elastase activity contributes to monocrotaline pulmonary vasculopathy and hypertension. On the other hand, cotreatment with SC39026 had no significant effect on the severity of the monocrotaline-induced lung inflammatory reaction, the pulmonary endothelial dysfunction, or the increase in lung hydroxyproline content. 相似文献
5.
Kevin Gruffydd-Jones Sandra Hollinghurst Sabbi Ward Gordon Taylor 《The British journal of general practice》2005,55(521):918-923
BACKGROUND: There is a high non-attendance rate for traditional clinic-based routine asthma care in general practice. Alternative methods of providing routine asthma care need to be examined. AIM: To examine the cost and effectiveness of targeted routine asthma care in general practice using telephone triage, compared to usual clinic care. DESIGN OF STUDY: An open randomised controlled trial. SETTING: A single semi-rural practice in the southwest of England. METHOD: Adult patients with asthma were randomised to receive either their routine asthma care in the surgery or care by telephone triage. Asthma control parameters, health status and NHS resource utilisation were measured over the 12-month study period. RESULTS: One hundred and ninety-four patients were randomised and 35% per cent more patients (n = 84 versus n = 62) received more than one consultation in the telephone group. Asthma control as measured by the asthma control questionnaire (ACQ) was similar in the clinic and telephone groups: mean change in ACQ = -0.11 (95% CI = -0.32 to 0.11) versus -0.18 (95% CI = -0.38 to 0.02). Mean NHS costs were 210 pounds sterling per patient per year in the telephone group compared to 334 pounds sterling in the clinic group (P-value of bootstrapped difference = 0.071). CONCLUSION: Targeted routine asthma care by telephone triage of adult asthmatics can lead to more asthma patients being reviewed, at less cost per patient and without loss of asthma control compared to usual routine care in the surgery. 相似文献
6.
Hand preferences and whole (Galago senegalensis) 总被引:1,自引:0,他引:1
The hand preferences in prey capture and whole-body turning biases after prey capture were assessed in 10 lesser bushbabies (Galago senegalensis) in 8 conditions designed to manipulate posture, visibility of prey and angle of reaching. Each subject received 60 trials in each test condition for a total of 480 trials. Seven subjects had a left-hand preference in food reaching, three right and none were ambipreferent. Eight subjects had a left whole-body turning bias, one right and one had no bias. No correlation was found between reach preference and turning bias. Bipedal posture facilitated the use of the dominant hand, whereas other manipulated conditions did not have a significant effect on hand use. A neuraxial arousal system is postulated as mediator of the bipedal effect on hand use. 相似文献
7.
8.
9.
Priti Bandi M.S. Vilma E. Cokkinides Ph.D. J. Lee Westmaas Ph.D. Elizabeth Ward Ph.D. 《The Journal of adolescent health》2008,43(6):612-615
There is limited information on the relationship between parental practices that specifically discourage current cigarette smoking and adolescent cessation, and how this relationship varies by age. Among 1629 adolescent smokers, self-reported receipt of parental communication not to smoke was significantly and positively associated with readiness to quit. The strength and significance of this association decreased from early to middle adolescence and was not significant in late adolescence. 相似文献
10.
Peripheral quantitative computed tomography in children and adolescents: the 2007 ISCD Pediatric Official Positions 总被引:2,自引:0,他引:2
Babette Zemel Shona Bass Teresa Binkley Gaele Ducher Heather Macdonald Heather McKay Laurie Moyer-Mileur John Shepherd Bonny Specker Kate Ward Didier Hans 《Journal of clinical densitometry》2008,11(1):59-74
Peripheral quantitative computed tomography (pQCT) has mainly been used as a research tool in children. To evaluate the clinical utility of pQCT and formulate recommendations for its use in children, the International Society of Clinical Densitometry (ISCD) convened a task force to review the literature and propose areas of consensus and future research. The types of pQCT technology available, the clinical application of pQCT for bone health assessment in children, the important elements to be included in a pQCT report, and quality control monitoring techniques were evaluated. The review revealed a lack of standardization of pQCT techniques, and a paucity of data regarding differences between pQCT manufacturers, models and software versions and their impact in pediatric assessment. Measurement sites varied across studies. Adequate reference data, a critical element for interpretation of pQCT results, were entirely lacking, although some comparative data on healthy children were available. The elements of the pQCT clinical report and quality control procedures are similar to those recommended for dual-energy X-ray absorptiometry. Future research is needed to establish evidence-based criteria for the selection of the measurement site, scan acquisition and analysis parameters, and outcome measures. Reference data that sufficiently characterize the normal range of variability in the population also need to be established. 相似文献