全文获取类型
收费全文 | 22784篇 |
免费 | 1105篇 |
国内免费 | 58篇 |
专业分类
耳鼻咽喉 | 455篇 |
儿科学 | 876篇 |
妇产科学 | 476篇 |
基础医学 | 2742篇 |
口腔科学 | 536篇 |
临床医学 | 1338篇 |
内科学 | 5837篇 |
皮肤病学 | 787篇 |
神经病学 | 1585篇 |
特种医学 | 520篇 |
外科学 | 3701篇 |
综合类 | 153篇 |
一般理论 | 7篇 |
预防医学 | 1965篇 |
眼科学 | 469篇 |
药学 | 1224篇 |
1篇 | |
中国医学 | 111篇 |
肿瘤学 | 1164篇 |
出版年
2023年 | 116篇 |
2022年 | 92篇 |
2021年 | 474篇 |
2020年 | 254篇 |
2019年 | 542篇 |
2018年 | 820篇 |
2017年 | 513篇 |
2016年 | 458篇 |
2015年 | 482篇 |
2014年 | 556篇 |
2013年 | 839篇 |
2012年 | 1414篇 |
2011年 | 1607篇 |
2010年 | 843篇 |
2009年 | 646篇 |
2008年 | 1309篇 |
2007年 | 1433篇 |
2006年 | 1325篇 |
2005年 | 1347篇 |
2004年 | 1238篇 |
2003年 | 1079篇 |
2002年 | 1107篇 |
2001年 | 852篇 |
2000年 | 1056篇 |
1999年 | 690篇 |
1998年 | 117篇 |
1997年 | 89篇 |
1996年 | 91篇 |
1995年 | 72篇 |
1994年 | 74篇 |
1993年 | 48篇 |
1992年 | 285篇 |
1991年 | 271篇 |
1990年 | 230篇 |
1989年 | 189篇 |
1988年 | 147篇 |
1987年 | 166篇 |
1986年 | 140篇 |
1985年 | 135篇 |
1984年 | 77篇 |
1983年 | 75篇 |
1982年 | 43篇 |
1981年 | 36篇 |
1979年 | 54篇 |
1978年 | 33篇 |
1974年 | 43篇 |
1973年 | 46篇 |
1972年 | 46篇 |
1971年 | 43篇 |
1970年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
G N Coston R B Sayetta H I Friedman M C Weinrich C A Macera K Meeks S K McAndrews K S Morales 《The Cleft palate-craniofacial journal》1992,29(1):87-91
The correct identification of syndromes and other congenital malformations at an early age is critical for the child, family and care providers. Most specialists who conduct large screenings of young children are not adequately trained to recognize signs and symptoms that should lead to appropriate referral to the clinical geneticist and/or diagnostic team. A systematic approach for recognizing important signs is presented here; a Craniofacial Screening Profile. Following a brief training program, the Profile was validated by 39 speech-language pathologists in screening 3,539 kindergarten and first grade children. The results were excellent (specificity was 99.6%), demonstrating that with limited training, specialists can effectively screen for important signs and symptoms of a major group of syndromes and other congenital malformations. 相似文献
42.
Intraperitoneal chemotherapy was administered to 13 patients with peritoneal carcinomatosis, using acute peritoneal dialysis catheters immediately before the administration of the chemotherapy. A total of 59 cycles were administered, with insertion of the corresponding catheter. There were no inflow or outflow problems and no insertion-related complications. With the removal of the catheter after its use, there is no risk of abdominal infections. 相似文献
43.
M Girbau P R González-Guerrero L Bassas F de Pablo 《Molecular and cellular endocrinology》1992,90(1):69-75
The demonstration of growth factor receptors in very young embryos is limited by the difficulty in obtaining sufficient tissue to yield adequate membrane preparations. We have developed an in situ binding technique that allowed quantitation of [125I]insulin and [125I]insulin-like growth factor-I (IGF-I) binding to individual chick embryos. Specific binding per embryo increased from the youngest stage studied (Hamburger and Hamilton (HH) stages 3-4, gastrulating embryo of approximately 18-20 h) until the third day of development. At all ages, the binding of [125I]IGF-I was several fold higher than the binding of [125I]insulin. Autophosphorylation of the beta-subunit of the receptors was stimulated by insulin and IGF-I in a stage- and dose-dependent manner. The two peptides did not have an additive effect. The present studies further support our previous data showing the early developmental appearance of insulin and IGF-I receptors, which very likely are essential for normal embryo development. In addition, this in situ method for demonstration of receptors can be applied to other types of receptors present in isolated organs and young embryos. 相似文献
44.
A Morales M C Torres J L Megias A Candido A Maldonado 《Pharmacology, biochemistry, and behavior》1992,43(1):153-157
The effect of administration of diazepam on successive negative contrast in one-way avoidance learning was examined in rats. Contrast was induced by shifting rats from a large reward, 30 s spent in the safe compartment, to a small reward, 1 s spent in the safe compartment. IP administration of 2 mg/kg diazepam eliminated this negative contrast. Moreover, this effect is dose dependent, with doses of 2 and 2.5 mg/kg, but not 0.5 mg/kg, effective in reliably reducing contrast. These results suggest the existence of similar or common underlying mechanisms in both aversive and appetitive contrast effects; they are discussed in light of the current theories of frustrative nonreward and as a mean of studying the behavioral and biological mechanisms of anxiety. 相似文献
45.
The modifications in rat brain muscarinic acetylcholine receptors induced by acute immobilization stress lasting 10 min or 2 h were analyzed by quantitative in vitro autoradiography. [3H]N-Methylscopolamine ([3H]NMS) was used as a ligand. Immobilization stress for 10 min did not produce any significant change in the properties of [3H]NMS binding sites throughout the brain. In contrast, 2 h immobilization caused a significant increase in receptor affinity (Kd) without modification in the maximal number of receptors (Bmax) in several brain areas such as the caudate-putamen, cortical layers and CA1 field of the hippocampus, among others. These results, found even in animals killed immediately after the end of the immobilization sessions, suggest that immobilization stress induces supersensitivity of muscarinic receptors in certain cholinergic pathways in rat brain. 相似文献
46.
Ana María Fortuna Marco Balleza Núria Calaf Mercedes González Teresa Feixas Pere Casan 《Archivos de bronconeumologia》2009,45(3):143-147
Nitric oxide (NO) production has been described using a 2-compartment model for the synthesis and movement of NO in both the alveoli and the airways. The alveolar concentration of NO (CaNO), an indirect marker of the inflammatory state of the distal portions of the lung, can be deduced through exhalation at multiple flow rates. Our objective was to determine reference values for CaNO. The fraction of exhaled NO (FeNO) was measured in 33 healthy individuals at a rate of 50 mL/s; the subjects then exhaled at 10, 30, 100, and 200 mL/s to calculate CaNO. A chemiluminescence analyzer (NIOX Aerocrine) was used to perform the measurements. The mean (SD) FeNO was 15 (6) ppb. The mean CaNO was 3.04 (1.30) ppb. These values of CaNO measured in healthy individuals will allow us to analyze alveolar inflammatory behavior in respiratory and systemic processes. 相似文献
47.
Bacterial DNA in patients with cirrhosis and sterile ascites. Its role as a marker of bacterial translocation and prognostic tool] 总被引:1,自引:0,他引:1
J M González-Navajas R Francés J Such 《Revista española de enfermedades digestivas》2007,99(10):599-603
During the last decade, we have witnessed an increase in the amount of data related with the presence of bacterial translocation in experimental models of cirrhosis. However, clinical studies have been limited by the lack of non-invasive methods to study this phenomenon. Over the past years, the research developed in our laboratory has been focused on the detection of bacterial DNA in serum and ascitic fluid of patients with cirrhosis and sterile ascites, the clinical and immunological implications of such finding. Initially, by means of a polymerase chain reaction (PCR)-based method and automated nucleotide sequencing, we were able to detect and identify the presence of fragments of bacterial DNA in the mentioned patients with culture-negative, non-neutrocytic ascites. Since then, we have accumulated a core of data suggesting that the presence of bacterial DNA may have an important role not only as a marker of bacterial translocation, but also as a short-term prognostic factor. Here, we discuss the past, present and future of this line of investigation. 相似文献
48.
Mònica Gratacòs Juan R González Josep M Mercader Rafael de Cid Mikel Urretavizcaya Xavier Estivill 《Neuropsychopharmacology》2007,61(7):911-922
BACKGROUND: There is an increasing recognition that the pathophysiology of mental disorders could be the result of deregulation of synaptic plasticity with alterations of neurotrophins. The valine (Val)66-to-methionine (Met) variant, located in the pro brain-derived neurotrophic factor (BDNF) sequence, has been extensively studied through linkage and association approaches in several psychiatric disorders. METHODS: We performed a meta-analysis restricted to individual case-control studies in different categories of mental disorders and BDNF Val66Met polymorphism. We included data from 39 case-control studies encompassing psychiatric phenotypes: eating disorders, substance-related disorders, mood disorders, and schizophrenia, among others. RESULTS: The association of Val66Met was confined to three diagnoses: substance-related disorders, eating disorders, and schizophrenia. The Val/Met and the Met/Met genotypes increase the risk for eating disorders up to 33%, while these same genotypes confer a 21% protective effect in substance-related disorders. The homozygous carriers Met/Met showed a 19% increased risk of schizophrenia with respect to the heterozygous state. CONCLUSIONS: The study confirms the association of Val66Met to substance-related disorders, eating disorders, and schizophrenia. It remains to be determined if other variants in tight linkage disequilibrium with Val66Met could configure an extended functional haplotype that would explain observed discrepancies in risk estimations across studies. 相似文献
49.
50.
E Garza González E Giasi González M A Martínez Vázquez G I Pérez Pérez G M González H J Maldonado Garza F J Bosques Padilla 《Revista española de enfermedades digestivas》2007,99(2):71-75
OBJECTIVE: to assess the efficacy of rabeprazole (RPZ), amoxicillin (Am), and clarithromycin (Cla) (7 vs. 14 days) in the eradication of H. pylori, and to determine the effect of strain-specific antibiotic resistance and host CYP2C19 status. MATERIAL AND METHODS: first, we determined the CYP2C19 status of 100 healthy subjects to establish a sample size for the clinical trial. Then, 59 H. pylori-infected patients were randomized to receive RPZ (20 mg daily) plus Cla (500 mg b.d.) and Am (1,000 mg b.d.) for 7 vs. 14 days. The MIC for Am and Cla were determined using the agar dilution method. The CYP2C19 genotype was determined by the PCR-RFLP method. RESULTS: In the per-protocol analysis (PP) eradication rates were 89.7 and 72% for the 7- and 14-day groups (p = 0.159). In the intention to-treat analysis (ITT) eradication rates were 86.7 and 62.1% in the 7- and 14-day groups, respectively (p = 0.06).None of the strains was resistant to Am, and 4 strains were resistant to Cla: 3 (11.1%) in the 14-day group and 1 (4%) in the 7-day group. Neither strain-specific antibiotic resistance nor host CYP2C19 status influenced eradication rates. CONCLUSIONS: both 7- and 14-day therapies were effective for H. pylori eradication. Strain resistance and CYP2C19 status do not seem to influence eradication rates in the studied population. 相似文献