全文获取类型
收费全文 | 52310篇 |
免费 | 4352篇 |
国内免费 | 122篇 |
专业分类
耳鼻咽喉 | 566篇 |
儿科学 | 1640篇 |
妇产科学 | 1081篇 |
基础医学 | 6936篇 |
口腔科学 | 1168篇 |
临床医学 | 6302篇 |
内科学 | 9601篇 |
皮肤病学 | 707篇 |
神经病学 | 5427篇 |
特种医学 | 1713篇 |
外国民族医学 | 3篇 |
外科学 | 6931篇 |
综合类 | 964篇 |
一般理论 | 47篇 |
预防医学 | 5355篇 |
眼科学 | 910篇 |
药学 | 4073篇 |
中国医学 | 64篇 |
肿瘤学 | 3296篇 |
出版年
2023年 | 329篇 |
2022年 | 483篇 |
2021年 | 1155篇 |
2020年 | 674篇 |
2019年 | 1077篇 |
2018年 | 1250篇 |
2017年 | 960篇 |
2016年 | 995篇 |
2015年 | 1171篇 |
2014年 | 1622篇 |
2013年 | 2360篇 |
2012年 | 3472篇 |
2011年 | 3667篇 |
2010年 | 2078篇 |
2009年 | 1813篇 |
2008年 | 3165篇 |
2007年 | 3113篇 |
2006年 | 3049篇 |
2005年 | 3123篇 |
2004年 | 2833篇 |
2003年 | 2748篇 |
2002年 | 2595篇 |
2001年 | 941篇 |
2000年 | 798篇 |
1999年 | 794篇 |
1998年 | 606篇 |
1997年 | 474篇 |
1996年 | 494篇 |
1995年 | 423篇 |
1994年 | 378篇 |
1993年 | 329篇 |
1992年 | 526篇 |
1991年 | 502篇 |
1990年 | 506篇 |
1989年 | 467篇 |
1988年 | 403篇 |
1987年 | 413篇 |
1986年 | 354篇 |
1985年 | 389篇 |
1984年 | 362篇 |
1983年 | 314篇 |
1982年 | 334篇 |
1981年 | 269篇 |
1980年 | 301篇 |
1979年 | 267篇 |
1978年 | 261篇 |
1977年 | 217篇 |
1976年 | 183篇 |
1975年 | 176篇 |
1974年 | 199篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
Michael Rosenzweig Martha Skinner Tatiana Prokaeva Roger Théberge Catherine Costello Brian M Drachman Lawreen H Connors 《Amyloid》2007,14(1):65-71
We report the identification of a new transthyretin (TTR) gene mutation and variant protein, Glu61Gly, in a 55-year-old man with progressive cardiomyopathy, mild peripheral neuropathy and bilateral carpal tunnel syndrome. A diagnosis of TTR-associated familial amyloidosis (ATTR) was considered after an endomyocardial biopsy revealed amyloid deposits in the heart of a patient who had no family history of amyloidosis and no evidence of a plasma cell dyscrasia. Serum screening for a TTR variant by isoelectric focusing (IEF) was positive and prompted further studies to identify the genetic abnormality and to characterize the amyloidogenic protein. Direct DNA sequence analysis of all four coding regions in the TTR gene demonstrated heterozygosity in exon 3. Near equal amounts of guanine (G) and adenine (A) were observed at the second base position of codon 61. The wild-type (GAG) and mutated (GGG) sequences found in codon 61 correspond to glutamic acid (Glu) and glycine (Gly) residues, amino acids which differ in mass by -72 Da. Mass spectrometric analyses of TTR immunoprecipitated from serum showed the presence of both wild-type and variant proteins. The observed mass results for the wild-type and variant proteins were consistent with the predicted values calculated from the genetic analysis data. 相似文献
42.
The influence of protein solubilisation, conformation and size on the burst release from poly(lactide-co-glycolide) microspheres. 总被引:5,自引:0,他引:5
Gayle Duncan Thomas J Jess Farahidah Mohamed Nicholas C Price Sharon M Kelly Christopher F van der Walle 《Journal of controlled release》2005,110(1):34-48
Encapsulation of proteins in poly(lactide-co-glycolide) microspheres via emulsion is known to cause insoluble protein aggregates. Following protein emulsification and encapsulation in PLGA microspheres, we used circular dichroism to show that the recoverable soluble protein fraction also suffers subtle conformational changes. For a panel of proteins selected on the basis of molecular size and structural class, conformational stability measured by chemical denaturation was not indicative of stability during emulsion-encapsulation. Partial loss of structure was observed for alpha-helical proteins released from freeze-dried microspheres in aqueous buffer, with dramatic loss of structure for a beta-sandwich protein. The addition of sucrose (a lyoprotectant) did not prevent the loss of protein conformation upon encapsulation. Therefore, the conformational changes seen for the released soluble protein fraction originates during emulsification rather than microsphere freeze-drying. Analysis of the burst release for all proteins in buffer containing denaturant or surfactant showed that the degree of protein solubilisation was the dominant factor in determining the initial rate and extent of release. Our data for protein release into increasing concentrations of denaturing buffer suggest that the emulsion-denatured protein fraction remains insoluble; this fraction may represent the protein loss encountered upon comparison of protein encapsulated versus protein released. 相似文献
43.
44.
Timothy M. Pawlik Kelly Olino Ana Luiza Gleisner Michael Torbenson Richard Schulick Michael A. Choti 《Journal of gastrointestinal surgery》2007,11(7):860-868
Some investigators have suggested that preoperative chemotherapy for hepatic colorectal metastases may cause hepatic injury
and increase perioperative morbidity and mortality. The objective of the current study was to examine whether treatment with
preoperative chemotherapy was associated with hepatic injury of the nontumorous liver and whether such injury, if present,
was associated with increased morbidity or mortality after hepatic resection. Two-hundred and twelve eligible patients who
underwent hepatic resection for colorectal liver metastases between January 1999 and December 2005 were identified. Data on
demographics, clinicopathologic characteristics, and preoperative chemotherapy details were collected and analyzed. The majority
of patients received preoperative chemotherapy (n = 153; 72.2%). Chemotherapy consisted of fluoropyrimidine-based regimens: 5-FU monotherapy, 31.6%; irinotecan, 25.9%; and
oxaliplatin, 14.6%. Among those patients who received chemotherapy, the type of chemotherapy regimen predicted distinct patterns
of liver injury. Oxaliplatin was associated with increased likelihood of grade 3 sinusoidal dilatation (p = 0.017). Steatosis >30% was associated with irinotecan (27.3%) compared with no chemotherapy, 5-FU monotherapy, and oxaliplatin
(all p < 0.05). Irinotecan also was associated with steatohepatitis, as two of the three patients with steatohepatitis had received
irinotecan preoperatively. Overall, the perioperative complication rate was similar between the no-chemotherapy group (30.5%)
and the chemotherapy group (35.3%) (p = 0.79). Preoperative chemotherapy was also not associated with 60-day mortality. In patients with hepatic colorectal metastases,
preoperative chemotherapy is associated with hepatic injury in about 20 to 30% of patients. Furthermore, the type of hepatic
injury after preoperative chemotherapy was regimen-specific.
Presented at the American Hepato-Pancreato-Biliary Association 2006 Annual Meeting, March 11, Miami, Florida. 相似文献
45.
46.
HEAD CIRCUMFERENCE AND INTELLECTUAL PERFORMANCE OF PATIENTS WITH DUCHENNE MUSCULAR DYSTROPHY 总被引:3,自引:1,他引:2
R. E. Appleton K. Bushby D. Gardner-Medwin J. Welch P. J. Kelly 《Developmental medicine and child neurology》1991,33(10):884-890
The head circumferences of 64 patients with Duchenne muscular dystrophy were measured and found to be greater than those of a normal population. The patients had relative, and in 12 cases, absolute macrocephaly. 47 of the 64 patients underwent intelligence testing and were found to be significantly intellectually impaired, particularly in verbal and language skills. There was no correlation between head circumference or absolute macrocephaly and intellectual performance. The cause of macrocephaly in these patients is unknown and its relevance to the aetiology of intellectual impairment in Duchenne muscular dystrophy is not yet clear. 相似文献
47.
Kelly Garrett Allison Butler Wayne R Cohen 《The journal of maternal-fetal & neonatal medicine》2005,17(1):49-53
OBJECTIVE: To characterize dysfunctional labors that lead to cesarean delivery in the second stage and to assess the accuracy of diagnoses of abnormal fetal descent. METHODS: Thirty-one patients delivered by cesarean during the second stage because of abnormal labor or presumed cephalopelvic disproportion were studied and compared to 62 control cesarean cases delivered for the same indications in the first stage. The clinical diagnosis of dysfunctional labor that led to the cesarean was compared to the diagnosis made by retrospective analysis of the labor curves. RESULTS: Cases did not differ from controls delivered in the first stage in maternal age, race, parity, gestational age, weight gain, or the frequency of associated medical complications. The newborns were not significantly different in birth weight,ponderal index, sex, or the incidence of low Apgar scores. Among study patients, 94% had a second stage labor dysfunction determined by graphic labor analysis, predominantly arrest of descent (69%) and failure of descent (28%). In 79% of cases a dysfunctional first stage preceded the abnormal second stage. Among these first stage labor abnormalities, 68% were not recognized during the labor. CONCLUSION: Characteristics of patients delivered by cesarean during the second stage were similar to those delivered before full cervical dilatation. Second stage labor abnormalities were usually preceded by an abnormal first stage. There was considerable inaccuracy in the diagnosis of second stage labor dysfunction. 相似文献
48.
Stimulation by mitogens and neuronal membranes of lymphocytes from patients with motor neurone disease 总被引:1,自引:0,他引:1
Jaqueline Aspin Roger Harrison Ahmed Jehanli George Lunt Malcolm Campbell 《Journal of neuroimmunology》1986,11(1):31-40
Stimulation of lymphocytes from motor neurone disease patients by either concanavalin A or PHA was shown to be significantly depressed relative to that from normal controls, as assayed by incorporation of [3H]thymidine or [3H]leucine or by glucose uptake. Corresponding significant differences were not shown by assays based upon incorporation of [3H]uridine or of lactate release. Lymphocytes from 4 out of 14 motor neurone disease patients showed a blastogenic response to membranes from rat spinal cord cells, compared with those from 0 out of 9 normal controls. These results not only suggest the possibility of an impaired cellular immune control in MND patients but also indicate the presence of lymphocytes sensitised specifically to neuronal membrane components. 相似文献
49.
50.