全文获取类型
收费全文 | 2010篇 |
免费 | 180篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 76篇 |
妇产科学 | 20篇 |
基础医学 | 305篇 |
口腔科学 | 29篇 |
临床医学 | 234篇 |
内科学 | 474篇 |
皮肤病学 | 13篇 |
神经病学 | 179篇 |
特种医学 | 188篇 |
外国民族医学 | 1篇 |
外科学 | 196篇 |
综合类 | 56篇 |
一般理论 | 2篇 |
预防医学 | 193篇 |
眼科学 | 42篇 |
药学 | 125篇 |
中国医学 | 3篇 |
肿瘤学 | 62篇 |
出版年
2020年 | 18篇 |
2019年 | 27篇 |
2018年 | 22篇 |
2017年 | 16篇 |
2016年 | 28篇 |
2015年 | 25篇 |
2014年 | 47篇 |
2013年 | 56篇 |
2012年 | 79篇 |
2011年 | 66篇 |
2010年 | 42篇 |
2009年 | 53篇 |
2008年 | 72篇 |
2007年 | 96篇 |
2006年 | 71篇 |
2005年 | 83篇 |
2004年 | 90篇 |
2003年 | 77篇 |
2002年 | 75篇 |
2001年 | 59篇 |
2000年 | 57篇 |
1999年 | 53篇 |
1998年 | 52篇 |
1997年 | 39篇 |
1996年 | 31篇 |
1995年 | 23篇 |
1994年 | 19篇 |
1993年 | 24篇 |
1992年 | 53篇 |
1991年 | 46篇 |
1990年 | 54篇 |
1989年 | 43篇 |
1988年 | 53篇 |
1987年 | 48篇 |
1986年 | 55篇 |
1985年 | 34篇 |
1984年 | 19篇 |
1983年 | 27篇 |
1982年 | 23篇 |
1981年 | 18篇 |
1980年 | 20篇 |
1979年 | 21篇 |
1978年 | 21篇 |
1977年 | 24篇 |
1976年 | 21篇 |
1975年 | 20篇 |
1974年 | 21篇 |
1972年 | 21篇 |
1971年 | 23篇 |
1970年 | 16篇 |
排序方式: 共有2201条查询结果,搜索用时 18 毫秒
61.
Teerenhovi L; Knuutila S; Ekblom M; Rossi L; Borgstrom GH; Tallman JK; Andersson L; de la Chapelle A 《Blood》1984,64(5):1116-1122
A major problem in the cytogenetic analysis of hematologic neoplasms has been an inability to identify the cell from which the chromosomes were obtained. We describe a procedure that allows simultaneous analysis of karyotype and cell cytology in mitotic cells. The method differs from conventional cytogenetic analysis in that after mild hypotonic treatment, the cells are cytocentrifuged onto glass slides. In mitotic cells, this procedure often results in adequate spread of the chromosomes within the intact cell membrane. The cytoplasmic structure also remains intact, so that cytologic preparations are of good quality. Morphologic and immunologic identification of mitotic cells can be done using routine hematologic stains, such as Giemsa or Sudan black B, and various antisera using immunofluorescence techniques. The chromosomes can be simultaneously analyzed either without banding on slides stained with Giemsa or with Q-banding on slides stained with immunofluorescence techniques. Identification of numerical and structural karyotype aberrations thus is possible in morphologically identified cells. 相似文献
62.
Health status deterioration in patients with chronic obstructive pulmonary disease 总被引:13,自引:0,他引:13
Spencer S Calverley PM Sherwood Burge P Jones PW;ISOLDE Study Group. Inhaled Steroids in Obstructive Lung Disease 《American journal of respiratory and critical care medicine》2001,163(1):122-128
This study examined health status decline in patients with chronic obstructive pulmonary disease (COPD). Data are from the Inhaled Steroids in Obstructive Lung Disease (ISOLDE) trial. After an 8-wk run-in, 751 patients (566 male), mean age 64 yr, were randomized to receive fluticasone propionate (FP) 500 microg twice daily (376 patients) or placebo (375 patients). Mean baseline postbronchodilator FEV1 was 50 +/- 15% predicted. Patients completed the St George's Respiratory Questionnaire (SGRQ) and the Short-Form 36 (SF-36) at baseline and every 6 mo for 3 yr. FEV1 and smoking status were assessed at baseline and at 3-mo intervals. A total of 387 (212 FP) patients completed the trial. All SGRQ components (p = 0.03 to 0.004) and Physical Function, Mental Health, Energy/ Vitality, and Physical Role Limitation scales of the SF-36 (p = 0.05 to 0.005) deteriorated faster in the placebo group. FEV1 and SGRQ scores correlated at baseline values (r = -0.25, p < 0.0001), as did change in FEV1 and change in SGRQ (Delta r = -0.24, p < 0.0001). At baseline values smokers had worse SGRQ Total, Symptoms, and Impacts scores than ex-smokers. This difference was maintained throughout the study. Smoking status did not influence the rate of decline in health status. The SGRQ Total scores of FP-treated patients took 59% longer than placebo to deteriorate by a clinically significant amount. We conclude that health status decline in moderate to severe COPD can be reduced by high-dose fluticasone. 相似文献
63.
1,25-Dihydroxyvitamin D3 suppresses parathyroid hormone secretion from bovine parathyroid cells in tissue culture 总被引:7,自引:0,他引:7
To determine whether 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] regulates PTH secretion, we have tested its effects in both short term incubations (30-120 min) and long term primary cell cultures (24-96 h) of bovine parathyroid cells. In short term incubations, 10(-11)-10(-7) M 1,25-(OH)2D3 had no consistent effect on PTH secretion. In primary cultures of bovine parathyroid cells, significant suppression of PTH secretion occurred, as measured by both N-terminal and C-terminal PTH assays. Suppression of PTH secretion was dose dependent when 10(-11), 10(-9), and 10(-7) M 1,25-(OH)2D3 were tested for 48 h in culture, and the effects of 10(-7) M, 1,25-(OH)2D3 were noted as early as 24 h. Reversal of suppression of PTH secretion was observed after an additional 48 h in the absence of 1,25-(OH)2D3. Other studies from our laboratory have demonstrated that 1,25-(OH)2D3 suppresses levels of pre-pro-PTH mRNA in cultured bovine parathyroid cells, and we found a strong correlation at 48 h between the decrease in PTH release and that in mRNA. We conclude that 1) 1,25-(OH)2D3 suppresses PTH secretion rates in a dose-dependent manner in cells grown for 24-48 h in culture, but does not have a significant effect on short term PTH release (30-120 min); 2) cultured cells exhibiting suppression by 1,25-(OH)2D3 demonstrate nearly full recovery of PTH secretion after an additional 48 h in the absence of added 1,25-(OH)2D3; and 3) PTH secretion closely parallels levels of pre-pro-PTH mRNA in cultured cells, suggesting that the observed effects of PTH secretion reflect, at least in part, suppression of synthesis of PTH by 1,25-(OH)2D3. 相似文献
64.
Soriano JB Sin DD Zhang X Camp PG Anderson JA Anthonisen NR Buist AS Burge PS Calverley PM Connett JE Petersson S Postma DS Szafranski W Vestbo J 《Chest》2007,131(3):682-689
BACKGROUND: There is controversy about whether therapy with inhaled corticosteroids (ICSs) modifies the natural history of COPD, characterized by an accelerated decline in FEV(1). METHODS: The Inhaled Steroids Effect Evaluation in COPD (ISEEC) study is a pooled study of patient-level data from seven long-term randomized controlled trials of ICS vs placebo lasting >/= 12 months in patients with moderate-to-severe COPD. We have previously reported a survival benefit for ICS therapy in COPD patients using ISEEC data. We aimed to determine whether the regular use of ICSs vs placebo improves FEV(1) decline in COPD patients, and whether this relationship is modified by gender and smoking. RESULTS: There were 3,911 randomized participants (29.2% female) in this analysis. In the first 6 months after randomization, ICS use was associated with a significant mean (+/- SE) relative increase in FEV(1) of 2.42 +/- 0.19% compared with placebo (p < 0.01), which is quantifiable in absolute terms as 42 mL in men and 29 mL in women over 6 months. From 6 to 36 months, there was no significant difference between placebo and ICS therapy in terms of FEV(1) decline (-0.01 +/- 0.09%; p = 0.86). The initial treatment effect was dependent on smoking status and gender. Smokers who continued to smoke had a smaller increase in FEV(1) during the first 6 months than did ex-smokers. Female ex-smokers had a larger increase in FEV(1) with ICS therapy than did male ex-smokers. CONCLUSIONS: We conclude that in COPD in the first 6 months of treatment, ICS therapy is more effective in ex-smokers than in current smokers with COPD in improving lung function, and women may have a bigger response to ICSs than men. However, it seems that after 6 months, ICS therapy does not modify the decline in FEV(1) among those who completed these randomized clinical trials. 相似文献
65.
66.
Ken Takeuchi Simon Smale Purushothaman Premchand Laurence Maiden Roy Sherwood Bjarni Thjodleifsson Einar Bjornsson Ingvar Bjarnason 《Clinical gastroenterology and hepatology》2006,4(2):196-202
BACKGROUND & AIMS: It has been variably suggested that nonselective NSAIDs and cyclooxygenase (COX)-2 selective inhibitors aggravate or ameliorate clinical disease activity in patients with inflammatory bowel disease. We assessed the effect of these drugs in patients with inflammatory bowel disease (n = 209) and the possible mechanisms. METHODS: First, patients with quiescent Crohn's disease and ulcerative colitis received the non-NSAID analgesic acetaminophen (n = 26) and the conventional NSAIDs naproxen (n = 32), diclofenac (n = 29), and indomethacin (n = 22) for 4 weeks. The Harvey-Bradshaw index was used to define relapse. Second, to assess the mechanism of relapse, intestinal inflammation was quantitated (fecal calprotectin) before and during treatment (20 patients/group) with acetaminophen, naproxen (topical effect, COX-1 and -2 inhibitor), nabumetone (COX-1 and -2 inhibitor), nimesulide (selective COX-2 inhibitor), and low-dose aspirin (selective COX-1 inhibition). RESULTS: Nonselective NSAIDs were associated with a 17%-28% relapse rate within 9 days of ingestion. No patient had an early relapse on acetaminophen, nimesulide, or aspirin, whereas those on naproxen and nabumetone (20%) experienced relapse. These clinical relapses were associated with escalating intestinal inflammatory activity. CONCLUSIONS: NSAID ingestion is associated with frequent and early clinical relapse of quiescent inflammatory bowel disease, and the mechanism appears to be due to dual inhibition of the COX enzymes. Selective COX-2 inhibition with nimesulide and COX-1 inhibition with low-dose aspirin appear to be well-tolerated in the short-term. 相似文献
67.
Mukamal KJ Maclure M Muller JE Sherwood JB Mittleman MA 《American heart journal》2004,147(6):999-1004
Background
Previous studies have generally suggested no effect of coffee consumption on the risk of acute myocardial infarction. The effect of coffee consumption on prognosis after acute myocardial infarction is uncertain.Methods
In an inception cohort study, we observed 1935 patients who were hospitalized with a confirmed acute myocardial infarction between 1989 and 1994 at 45 community hospitals and tertiary care centers in the United States, as part of the Determinants of Myocardial Infarction Onset Study. Trained interviewers assessed self-reported caffeinated coffee consumption before infarction with a standardized questionnaire. We analyzed survival censored at December 31, 1995, using Cox proportional hazards regression.Results
Of the 1902 patients for whom we had information on coffee intake, 315 (17%) died during a median follow-up period of 3.8 years. Coffee drinkers tended to be men, younger, and free of comorbidity, and they were more likely to be current smokers. Coffee consumption was not associated with an overall change in long-term post-infarction mortality rate. However, we did observe an unexpected and unexplained variation in the association between coffee consumption and mortality with time, with an apparent inverse association in the first 90 days after infarction.Conclusions
Self-reported coffee consumption has no overall association with post-infarction mortality. The unexpected time variation in the effect of coffee intake requires evaluation in other studies. 相似文献68.
Montaner AD Mongiat L Lux-Lantos VA Warby C Chewpoy B Bianchi MS Libertun C Rivier JE Sherwood NM Somoza GM 《Neuroendocrinology》2002,75(5):326-338
Gonadotropin-releasing hormone (GnRH) is a decapeptide widely known for its role in regulating vertebrate reproduction by serving as a signal from the hypothalamus to pituitary gonadotropes. The first form of GnRH to be identified was isolated from mammals (mGnRH) and the same form has been reported for all mammals studied, which includes marsupials and placental mammals. Later, another variant, chicken GnRH-II (cGnRH-II) was shown to be expressed together with mGnRH in the brains of all jawed vertebrates, including mammals such as rats, monkeys and humans. Our objective was to characterize a third form of GnRH that was isolated previously as mRNA from guinea pigs (gpGnRH), but has not been reported for any other mammal to date. Furthermore, the gonadotropic activity of gpGnRH has not been fully characterized. Our results, using chromatographical and immunological methods, show for the first time that gpGnRH is expressed together with mGnRH in some rodents (wild guinea pig and capybara), but not in others (mouse and hamster). Also, the gonadotropic activity of gpGnRH and mGnRH was tested in two different rat cell culture systems. Although there have been reports that the salmon(s) form of GnRH is present in mammals, we did not detect sGnRH in capybara, wild guinea pigs, hamsters, rats or mice. Taken together with previous reports, the present results support the idea that the expression of multiple GnRH variants in a single species is a common pattern in most vertebrate groups. 相似文献
69.
Buerger A Rozhitskaya O Sherwood MC Dorfman AL Bisping E Abel ED Pu WT Izumo S Jay PY 《Journal of cardiac failure》2006,12(5):392-398
BackgroundConditional gene inactivation in mice using the bacteriophage P1 Cre-loxP recombination system requires transgenic expression of Cre-recombinase driven by a tissue-specific or inducible promoter.Methods and ResultsUsing the cardiac α-myosin-heavy-chain promoter, the most commonly used myocardial-specific transgenic promoter, we created transgenic mice expressing Cre-recombinase in the heart. Seven transgenic lines developed dilated cardiomyopathy and premature death from congestive heart failure. One founder line that survived long enough to propagate had extremely high-level Cre recombinase expression. Transgenic lines that expressed low levels remained healthy. The high-expressing strain developed heart failure over a very predictable and reproducible time course. Detailed examination of the high-expressing strain revealed important molecular, cellular, and pharmacologic hallmarks of cardiomyopathy. First, “fetal genes” such as atrial natriuretic factor and brain natriuretic protein were expressed, a marker of pathologic cardiac hypertrophy and heart failure. Second, an increased incidence of cardiac myocyte apoptosis was present. Third, treatment of mice with captopril or metoprolol, drugs that delay the progression of heart failure, improved survival.ConclusionCre-recombinase when expressed at high levels may cause organ dysfunction, which could be mistaken for an effect of conditional gene inactivation. In addition, the stereotypic cardiomyopathy and disease progression in the characterized, high-expressing transgenic strain suggests its utility as a model to study the effects of pharmacologic or genetic manipulations in heart failure. 相似文献
70.
Thrombospondin mediates the cytoadherence of Plasmodium falciparum- infected red cells to vascular endothelium in shear flow conditions 总被引:3,自引:0,他引:3
Rock EP; Roth EF Jr; Rojas-Corona RR; Sherwood JA; Nagel RL; Howard RJ; Kaul DK 《Blood》1988,71(1):71-75
Cerebral malaria is thought to involve specific attachment of Plasmodium falciparum-infected knobby red cells to venular endothelium. The nature of surface ligands on host endothelial cells that may mediate cytoadherence is poorly understood. We have investigated the effects of soluble thrombospondin, rabbit antiserum raised against thrombospondin, and human immune serum on cytoadherence of parasitized erythrocytes in ex vivo mesocecum vasculature. Preincubation of infected red cells with soluble thrombospondin or human immune serum inhibits binding of infected red cells to rat venular endothelium. Infusion of the microcirculatory preparation with rabbit antithrombospondin antibodies before perfusion of parasitized erythrocytes also resulted in decreased cytoadherence. In addition, incubation of infected cells with human immune sera obtained from malaria patients significantly inhibited the observed cytoadherence. Our results indicate that thrombospondin mediates binding of infected red cells to venular endothelium and may thus be involved in the pathogenesis of cerebral malaria. 相似文献