全文获取类型
收费全文 | 614篇 |
免费 | 98篇 |
出版年
2018年 | 6篇 |
2016年 | 11篇 |
2015年 | 11篇 |
2014年 | 12篇 |
2013年 | 32篇 |
2012年 | 17篇 |
2011年 | 14篇 |
2010年 | 11篇 |
2009年 | 25篇 |
2008年 | 25篇 |
2007年 | 23篇 |
2006年 | 20篇 |
2005年 | 27篇 |
2004年 | 17篇 |
2003年 | 14篇 |
2002年 | 27篇 |
2001年 | 20篇 |
2000年 | 24篇 |
1999年 | 27篇 |
1998年 | 13篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1994年 | 9篇 |
1993年 | 12篇 |
1992年 | 8篇 |
1991年 | 14篇 |
1990年 | 15篇 |
1989年 | 20篇 |
1988年 | 20篇 |
1987年 | 10篇 |
1986年 | 16篇 |
1985年 | 18篇 |
1984年 | 15篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1980年 | 5篇 |
1979年 | 12篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 8篇 |
1973年 | 7篇 |
1972年 | 7篇 |
1971年 | 5篇 |
1969年 | 6篇 |
1968年 | 5篇 |
1967年 | 6篇 |
1966年 | 6篇 |
1961年 | 5篇 |
1960年 | 5篇 |
1954年 | 6篇 |
排序方式: 共有712条查询结果,搜索用时 15 毫秒
11.
The human apolipoprotein A-II gene is located on chromosome 1 总被引:7,自引:0,他引:7
K J Lackner S W Law H B Brewer A Y Sakaguchi S L Naylor 《Biochemical and biophysical research communications》1984,122(3):877-883
Apolipoprotein (apo) A-II is a major constituent of high density lipoproteins (HDL). The gene for apoA-II has been localized to the p21----qter region of chromosome 1 in man by Southern blot hybridization analysis of DNA from human-mouse cell hybrids using a cloned human apoA-II cDNA probe. The regional assignment was established using two hybrids carrying a reciprocal translocation involving chromosomes 1 and 2. Comparison with previously established gene loci on chromosomes 1 suggests that apoA-II may reside in a conserved linkage group with renin and peptidase C. On the other hand, apoA-II is not linked to the apoA-I gene, which has been localized previously to chromosome 11. 相似文献
12.
13.
14.
15.
16.
OBJECTIVE: To assess sex-related differences in coronary revascularization practices in a Canadian setting. DESIGN: Prospective analytic cohort study. SETTING: Regional referral office in Toronto. PATIENTS: A selected but consecutive group of 131 women and 440 men referred by cardiologists for revascularization procedures between Jan. 3, 1989, and June 30, 1991. INTERVENTIONS: Coronary artery bypass grafting (CABG) or percutaneous transluminal coronary angioplasty (PTCA). Nurse-coordinators placed the referral with a surgeon or interventional cardiologist at one of three hospitals, who then communicated directly with the referring cardiologist. MAIN OUTCOME MEASURES: Symptom status at referral, procedures requested and performed, and time from referral to procedure. RESULTS: Although the women were more likely than the men to have unstable angina at the time of referral (odds ratio [OR] 2.28, 95% confidence interval [CI] 1.38 to 3.79, p = 0.0006), more women than men (16.8% v. 12.1%) were turned down for a procedure. Significant sex-related differences in practice patterns (p < 0.001) persisted after controlling for age or for the referring cardiologists'' perception of expected procedural risk. A stepwise multivariate model showed that anatomy was the main determinant of case management; sex was the only other significant variable (p = 0.016). The referring physicians requested CABG more often for men than for women (p = 0.009), and the men accepted for a procedure were much more likely to undergo CABG than the women (OR 2.40, CI 1.47 to 3.93, p = 0.0002). Although the women undergoing CABG waited shorter periods than the men (p = 0.0035), this difference was attributable to their more severe symptoms. CONCLUSIONS: In this selected group women had more serious symptoms before referral but were turned down for revascularization more often than men. Reduced use of CABG rather than PTCA largely accounted for the sex-related differences in revascularization. Once accepted for a procedure women had shorter waiting times, which was appropriate given their more severe symptoms. 相似文献
17.
Glucocorticoids or the glucocorticoid analog dexamethasone (DEX) enhances the differentiation of preadipocytes in the presence of insulin and influences preadipocyte proliferation. The purpose of the present study was to determine if DEX can induce the recruitment of preadipocytes. Using monoclonal antibodies for complement-mediated cytotoxicity, preadipocytes were removed from porcine stromal vascular (S-V) cell cultures. Our experiments demonstrated for the first time that after removal of preadipocytes by cytotoxicity, preadipocytes or fat cells could be induced by DEX or DEX plus insulin but not by insulin alone. However, many more fat cells were induced (258 ± 15/unit area) when DEX was added with fetal bovine serum (FBS) followed with insulin treatment, compared to DEX with insulin (21.3 ± 5.1/ unit area) after removal of preadipocytes. Immunocyto-chemistry with AD-3, a preadipocyte marker, showed that DEX with FBS for 3 days after seeding (i.e., the proliferation phase) produced many more preadipocytes (AD-3 positive, 223 ± 45/unit area) than FBS alone (10.5 ± 1.4/unit area). Bromodeoxyuridine (BrdU) incorporation assays demonstrated that the efficiency of DEX with FBS (i.e., during proliferation) was mitosis dependent. Accordingly, we conclude that: porcine S-V cultures contain preadipocytes at different stages of differentiation and that DEX induced early preadipocyte differentiation depends on mitosis. 相似文献
18.
Beset by unprecedented fiscal pressures, Canadian medicare has reached a crossroads. The authors review the impact of recent cuts in federal transfer payments on provincial health care programs and offer seven suggestions to policymakers trying to accommodate these reductions. (1) Go slowly: public health care spending is no longer rising and few provinces have the necessary systems in place to manage major reductions. (2) Target reductions, rewarding quality and efficiency instead of making across-the-board cuts. (3) Replace blame with praise:give health care professionals and institutions credit for their contributions. (4) Learn from the successful programs and policies already in place across the country. (5) Foster horizontal and vertical integration of services. (6) Promote physician leadership by rewarding efforts to promote the efficient use of resources. (7) Monitor the effects of cutbacks: physician groups should cooperate with government in maintaining a national "report card" on services, costs and the health status of Canadians. 相似文献
19.
Z He R Yamamoto E E Furth L J Schantz S L Naylor H George J T Billheimer J F Strauss 《DNA and cell biology》1991,10(8):559-569
Sterol carrier protein 2 (SCP2) is believed to play a key role in intracellular lipid movement. Here we report the cloning and nucleotide sequences of cDNAs encoding SCP2-related proteins of 58.85 kD and 30.8 kD and the assignment of the SCP2 gene to human chromosome 1 p21-pter. The SCP2-related proteins share common deduced carboxyl amino acid sequences with SCP2 and the cDNAs have a common 3' untranslated nucleotide sequence. The mRNAs encoding these proteins increased in a coordinate fashion as human placental cytotrophoblasts differentiated into syncytiotrophoblasts in culture. Our observations document the existence of a family of related proteins encoded by the human SCP2 gene. 相似文献
20.
James E. Evans Howard Tieckelmann Edwin W. Naylor Robert Guthrie 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1979,163(1):29-36
A rapid procedure for the isolation, separation, identification and measurement of urinary pyrimidine bases and nucleosides by high-performance liquid chromatography (HPLC) is presented. The initial isolation of these compounds from urine was accomplished with small disposable ion-exchange columns. HPLC was performed on a silica gel column with a mobile phase composed of methylene chloride, methanol and 1 M aqueous ammonium formate buffer. Peaks were recorded at both 254 nm and 280 nm and the response ratio was used in conjunction with the elution volume for compound identification. The minimum detectable amount (signal-to-noise ratio = 2) ranged from 0.2 ng for uracil to 2.2 ng for cytidine. Linearity and recovery for thymine, uracil, uridine, pseudouridine, orotic acid and orotidine added to urine was demonstrated over almost a 103 concentration range. The potential application of this method for the study of inborn errors in the urea cycle is discussed. 相似文献