全文获取类型
收费全文 | 724篇 |
免费 | 28篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 10篇 |
妇产科学 | 29篇 |
基础医学 | 128篇 |
口腔科学 | 19篇 |
临床医学 | 75篇 |
内科学 | 184篇 |
神经病学 | 58篇 |
特种医学 | 21篇 |
外科学 | 85篇 |
预防医学 | 36篇 |
眼科学 | 6篇 |
药学 | 25篇 |
肿瘤学 | 72篇 |
出版年
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 10篇 |
2015年 | 5篇 |
2014年 | 6篇 |
2013年 | 20篇 |
2012年 | 22篇 |
2011年 | 35篇 |
2010年 | 19篇 |
2009年 | 19篇 |
2008年 | 38篇 |
2007年 | 26篇 |
2006年 | 41篇 |
2005年 | 40篇 |
2004年 | 46篇 |
2003年 | 50篇 |
2002年 | 33篇 |
2001年 | 14篇 |
2000年 | 11篇 |
1999年 | 23篇 |
1998年 | 11篇 |
1997年 | 13篇 |
1996年 | 8篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 12篇 |
1991年 | 9篇 |
1990年 | 17篇 |
1989年 | 11篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 11篇 |
1985年 | 15篇 |
1984年 | 13篇 |
1983年 | 19篇 |
1982年 | 12篇 |
1981年 | 15篇 |
1980年 | 11篇 |
1979年 | 8篇 |
1978年 | 16篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1974年 | 3篇 |
1972年 | 3篇 |
1970年 | 8篇 |
1969年 | 3篇 |
1968年 | 3篇 |
排序方式: 共有756条查询结果,搜索用时 15 毫秒
1.
R Vihko A Alanko V Isomaa A Kauppila 《Medical oncology and tumor pharmacotherapy》1986,3(3-4):197-210
The predictive value of female sex steroid, estrogen and progesterone, receptor (ER and PR, respectively) assays in breast, endometrial and ovarian cancer is reviewed with emphasis on comparative aspects of these malignant tumors in relation to their hormone dependency. The endocrine etiology of these three tumor types seems to be at least partly different, and so is the expression of these receptors in normal and malignant tissues of the breast, endometrium and ovary. There is a tendency for decreased receptor concentrations and disappearance of these receptors in association with advancement of these malignancies. There is also a decrease in the presence and concentrations of ER and PR in relation to loss of differentiation in breast and endometrial cancer. Receptor analyses have an established position in the selection of patients with advanced breast cancer for endocrine treatment, and they give promise of a similar application in endometrial cancer and in endometrioid cancer of the ovary. It is not clear whether the disease-free interval is related to the presence or concentrations of ER or PR as such in the tumor tissue. There is better survival in breast cancer patients with receptor-positive tumors, which might be due to a response to endocrine treatment. The same seems to be true for patients with endometrial cancer. Future progress in the application of female sex steroid receptor analyses in breast, endometrial and ovarian cancer needs additional controlled clinical trials and more highly developed receptor assays. 相似文献
2.
The structure of the title compound was determined by X-ray analysis. Medicinal compounds with Schiff base structure have been widely synthesized and investigated in recent years. The functional group-CH?N- of the Schiffbases has been shown to have considerable biological importance1) . Many compounds with such a structure have important analgesic, anti-inflammatory, antibiotic, antimicrobial and especi ally anticancer activities2-8). Medicinal sulphonamides, having a primary amino group in their molecule, react very easily with salicylaldehyde or its derivatives9). Information about the exact structure of the reac tion products is rather scanty, however, even though the formation reaction of the base has been utilized in many analytical pr ocedures for medicinal sulphonamides9-12) and many such Schiff bases have been found to possess good bac teriostatic properties13-14). 相似文献
3.
Endometrial and colorectal tumors from patients with hereditary nonpolyposis colon cancer display different patterns of microsatellite instability
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Kuismanen SA Moisio AL Schweizer P Truninger K Salovaara R Arola J Butzow R Jiricny J Nyström-Lahti M Peltomäki P 《The American journal of pathology》2002,160(6):1953-1958
The colorectum and uterine endometrium are the two most commonly affected organs in hereditary nonpolyposis colon cancer (HNPCC), but the genetic basis of organ selection is poorly understood. As tumorigenesis in HNPCC is driven by deficient DNA mismatch repair (MMR), we compared its typical consequence, instability at microsatellite sequences, in colorectal and endometrial cancers from patients with identical predisposing mutations in the MMR genes MLH1 or MSH2. Analysis of non-coding (BAT25, BAT26, and BAT40) and coding mononucleotide repeats (MSH6, MSH3, MLH3, BAX, IGF2R, TGF beta RII, and PTEN), as well as MLH1- and MSH2-linked dinucleotide repeats (D3S1611 and CA7) revealed significant differences, both quantitative and qualitative, between the two tumor types. Whereas colorectal cancers displayed a predominant pattern consisting of instability at the BAT loci (in 89% of tumors), TGF beta RII (73%), dinucleotide repeats (70%), MSH3 (43%), and BAX (30%), no such single pattern was discernible in endometrial cancers. Instead, the pattern was more heterogeneous and involved a lower proportion of unstable markers per tumor (mean 0.27 for endometrial cancers versus 0.45 for colorectal cancers, P < 0.001) and shorter allelic shifts for BAT markers (average 5.1 bp for unstable endometrial cancers versus 9.3 bp for colorectal cancers, P < 0.001). Among the individual putative "target" loci, PTEN instability was associated with endometrial cancers and TGF beta RII instability with colon cancers. The different instability profiles in endometrial and colorectal cancers despite identical genetic predisposition underlines organ-specific differences that may be important determinants of the HNPCC tumor spectrum. 相似文献
4.
PTEN mutational spectra,expression levels,and subcellular localization in microsatellite stable and unstable colorectal cancers 总被引:9,自引:0,他引:9
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Zhou XP Loukola A Salovaara R Nystrom-Lahti M Peltomäki P de la Chapelle A Aaltonen LA Eng C 《The American journal of pathology》2002,161(2):439-447
PTEN on 10q23.3 encodes a dual-specificity phosphatase that negatively regulates the phosphoinositol-3-kinase/Akt pathway and mediates cell-cycle arrest and apoptosis. Germline PTEN mutations cause Cowden syndrome and a range of several different hamartoma-tumor syndromes. Hereditary nonpolyposis colon cancer (HNPCC) syndrome is characterized by germline mutations in the mismatch repair (MMR) genes and by microsatellite instability (MSI) in component tumors. Although both colorectal carcinoma and endometrial carcinoma are the most frequent component cancers in HNPCC, only endometrial cancer has been shown to be a minor component of Cowden syndrome. We have demonstrated that somatic inactivation of PTEN is involved in both sporadic endometrial cancers and HNPCC-related endometrial cancers but with different mutational spectra and different relationships to MSI. In the current study, we sought to determine the relationship of PTEN mutation, 10q23 loss of heterozygosity, PTEN expression, and MSI status in colorectal cancers (CRCs). Among 11 HNPCC CRCs, 32 MSI+ sporadic cancers, and 39 MSI- tumors, loss of heterozygosity at 10q23.3 was found in 0%, 8%, and 19%, respectively. Somatic mutations were found in 18% (2 of 11) of the HNPCC CRCs and 13% (4 of 32) of the MSI+ sporadic tumors, but not in MSI- cancers (P = 0.015). All somatic mutations occurred in the two 6(A) coding mononucleotide tracts in PTEN, suggestive of the etiological role of the deficient MMR. Immunohistochemical analysis revealed 31% (14 of 45) of the HNPCC CRCs and 41% (9 of 22) of the MSI+ sporadic tumors with absent or depressed PTEN expression. Approximately 17% (4 of 23) of the MSI- CRCs had decreased PTEN expression, and no MSI- tumor had complete loss of PTEN expression. Among the five HNPCC or MSI+ sporadic CRCs carrying frameshift somatic mutations with immunohistochemistry data, three had lost all PTEN expression, one showed weak PTEN expression levels, and one had mixed tumor cell populations with weak and moderate expression levels. These results suggest that PTEN frameshift mutations in HNPCC and sporadic MSI+ tumors are a consequence of mismatch repair deficiency. Further, hemizygous deletions in MSI- CRCs lead to loss or reduction of PTEN protein levels and contribute to tumor progression. Finally, our data also suggest that epigenetic inactivation of PTEN, including differential subcellular compartmentalization, occurs in CRCs. 相似文献
5.
6.
Three groups of mice were trained for 1, 4 and 5 months according to different running programs on a motor driven treadmill and the fatty acid oxidation capacity (FAO) and the activities of some enzymes of energy metabolism (cytochrome c oxidase, malate dehydrogenase, triosephosphate dehydrogenase, and lactate dehydrogenase) were determined from m. quadriceps femoris (MQF). Endurance training increased the FAO [5-month training 4 days/week, 30 min/day 22% (p less than 0.05); 1-month training, 7 days/week, 150 min/day 37% (p less than 0.001); 4-month training, 5 days/week, 60 min/day 24% (p less than 0.05)]. The activities of cytochrome c oxidase and malate dehydrogenase increased approx. 30% (p less than 0.001) whereas triosephosphate dehydrogenase and lactate dehydrogenase activities were not prominently influenced by training. The predominantly red part of MQF of untrained animals oxidized palmitate four times faster than the predominantly white part. The activities of cytochrome c oxidase and malate dehydrogenase were two times higher showing pronounced FAO in the red part. Endurance training increased the FAO and activities of oxidative enzymes in the red and white parts and in the whole muscle relatively equally resulting in similar differences between the muscle types after training. The absolute increase in the FAO of the red muscle was, however, manyfold when compared in chemical units to the white muscle. 相似文献
7.
The hydrolethalus syndrome: delineation of a "new", lethal malformation syndrome based on 28 patients 总被引:7,自引:0,他引:7
We describe a lethal malformation syndrome in 28 newborn infants from 18 families. The main manifestations were hydrocephalus (often with an unusual structure of the brain and the occipital bone), very small mandible, Polydactyly, congenital heart defect, abnormalities of the respiratory organs, and (different from the Meckel syndrome) normal kidneys. Polyhydramnios and stillbirth or neonatal death were the rule. Autosomal recessive inheritance is evident. This syndrome is another in the group of rare recessive disorders which are found in Finland. Because of the 25 % recurrence risk and possibilities for prenatal diagnosis, this syndrome should be recognized by paediatricians and, because of the frequent stillbirths, also by obstetricians and pathologists. The name hydrolethalus syndrome (hydramnios, hydrocephalus, lethality) may be of help in this. 相似文献
8.
V. Vihko J. SoimajÄrvi E. Karvinen P. Rahkila M. Havu 《European journal of applied physiology》1978,39(3):209-218
Summary On the basis of maximal oxygen uptake (
O2 max) 18 normal, healthy men were divided into two groups of equal size: moderately trained subjects (MTR) each having
O2 max below 65.0 ml·min–1·kg–1 body weight (54.0±8.3) and well trained subjects (WTR), whose
O2 max exceeded 65.0 ml·min–1·kg–1 body weight (69.2±4.1). The WTR group had slightly (non significant, n.s.) higher percentage of slow twitch, oxidative (SO) fibers in M. vastus lateralis and higher (n.s.) activities of cytochrome c oxidase (CytOx), succinate dehydrogenase (SDH), 3-hydroxyacyl-CoA-dehydrogenase (HADH), and citrate synthase (CS), while lactate dehydrogenase (LDH) activity was lower (n.s.). In the MTR group only, the SO-%, and the activities of CytOx, SDH and HADH correlated positively with
O2 max, and LDH negatively with
O2 max. These correlations were not significant in the WTR group possibly because of the adaptations produced by training in this group. Multiple regression analysis was used to elucidate the best combination of variables to explain the variance in
O2 max. The best model consisted of the sum of relative activities of oxidative muscle enzymes (CytOx, SDH, HADH, CS), muscle LDH activity, body fat content (% F) and lean body mass. This model explained 69% of the variance in
O2 max; and of the individual variables % F was of utmost importance. 相似文献
9.
Kunnas TA Lehtimäki T Karhunen PJ Laaksonen R Janatuinen T Vesalainen R Nuutila P Knuuti J Nikkari ST 《Journal of molecular medicine (Berlin, Germany)》2004,82(12):821-825
Most of the effects of estrogens are mediated by estrogen receptors. Vascular endothelial cells and smooth muscle cells express estrogen receptor (ESR1) in both genders. A long genotype group of a common thymine-adenine (TA) dinucleotide repeat polymorphism in the regulatory region of this gene has previously been related to coronary artery disease. The present study examined whether coronary blood flow is affected by this genotype. A total of 49 healthy men were genotyped by PCR and divided into three groups according to median number of the ESR1 promoter TA repeat (=19), i.e., in the short allele genotype group both alleles were of fewer than 19 repeats whereas in the long allele group both alleles were 19 repeats or more. The intermediate group comprised men who had one short and one long allele. Myocardial blood flow was measured by positron emission tomography using [15O]water, performed at rest and during adenosine stimulation. Men with long alleles had lower adenosine-stimulated coronary flow than those with short alleles and those with one short and one long allelle. Our results suggest that adenosine-stimulated myocardial perfusion is lower in subjects with ESR1 long alleles than the other TA repeat genotypes. 相似文献
10.
L. Viinikka O. Ylikorkala R. Vihko H. P. Wijnand M. Booij F. van der Veen 《European journal of clinical pharmacology》1979,15(5):349-355
Summary The pharmacokinetics of a new synthetic progestagen, Org 2969 (13-ethyl-11-methylene-18,19-dinor-17-pregn-4-en-20-yn-17-ol) and its presumed active metabolite, 3-keto-Org 2969, were studied in five healthy female volunteers. During the first part of the study (Phase I), four volunteers ingested as a single dose 50 µg (about 100 µCi) of [16-3H]-Org 2969 together with 50 µg of ethinyl oestradiol. During the second part (Phase II), ten days of pretreatment with non-readioactive Org 2969 and ethinyl oestradiol preceded dosing, which was similar to that in Phase I. The fifth volunteer ingested 2500 µg of Org 2969 as a single dose. The concentrations of Org 2969 and 3-keto-Org 2969 in serum were measured by specific radioimmunoassay, and by as radioactivity. The maximum serum level of Org 2969 of 0.2–0.3% of the dose/litre was obtained 0.8–1.3 h after administration, and it was followed by a mono-exponential decrease, the half-life being 1.3–1.5 hours. No difference in Org 2969 levels was seen between Phase I and Phase II studies. The maximum 3-keto-Org 2969 serum level in Phase I was 0.4–0.8% of the dose/litre, 1–3 h after administration. A two-compartment open body model adequately described the data. The half-life of elimination was 16 hours. There was a considerable change in the single dose kinetics between Phase I and Phase II in the case of 3-keto-Org 2969. In Phase II the maximum serum level was 2.0–3.4% of the dose/litre, and there was no significant change in half-life. The change was considered to be due to a decrease in the apparent volume of distribution as a result of an increased number of binding sites on sex hormone-binding globulin induced by ethinyl oestradiol during the pretreatment period, and/or to an increase in the fraction of Org 2969 metabolized to 3-keto-Org 2969. The two simultaneous processes contributed to the change in kinetics and to the production of a steady state level of 3-keto-Org 2969 which resulted in a steady state within the first 10 days of daily administration of Org 2969 and ethinyl oestradiol.The following codes and trivial names were used Org 2969
13-ethyl-11-methylene-18, 19-dinor-17-pregn-4-en-20-yn-17-ol
- 3-keto-Org 2969
13-ethyl-17-hydroxy-11-methylene-18, 19-dinor-17-pregn-4-en-20-yn-3-one
- ethinyl oestradiol
17-ethinyl-1,3,5(10)-oestratriene-3,17-diol
- lynestrenol
19-nor-17-pregn-4-en-20-yn-17-ol
- norgestrel
13-ethyl-17-hydroxy-18,19-dinor-17-pregn-4-en-20-yn-3-one 相似文献