全文获取类型
收费全文 | 894篇 |
免费 | 62篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 42篇 |
妇产科学 | 37篇 |
基础医学 | 133篇 |
口腔科学 | 64篇 |
临床医学 | 78篇 |
内科学 | 175篇 |
皮肤病学 | 15篇 |
神经病学 | 100篇 |
特种医学 | 65篇 |
外科学 | 81篇 |
综合类 | 32篇 |
预防医学 | 52篇 |
眼科学 | 9篇 |
药学 | 33篇 |
中国医学 | 5篇 |
肿瘤学 | 37篇 |
出版年
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 30篇 |
2020年 | 11篇 |
2019年 | 17篇 |
2018年 | 26篇 |
2017年 | 12篇 |
2016年 | 16篇 |
2015年 | 20篇 |
2014年 | 21篇 |
2013年 | 41篇 |
2012年 | 51篇 |
2011年 | 51篇 |
2010年 | 36篇 |
2009年 | 27篇 |
2008年 | 25篇 |
2007年 | 43篇 |
2006年 | 38篇 |
2005年 | 29篇 |
2004年 | 22篇 |
2003年 | 17篇 |
2002年 | 18篇 |
2001年 | 21篇 |
2000年 | 27篇 |
1999年 | 23篇 |
1998年 | 28篇 |
1997年 | 21篇 |
1996年 | 22篇 |
1995年 | 11篇 |
1994年 | 16篇 |
1993年 | 10篇 |
1992年 | 15篇 |
1991年 | 22篇 |
1990年 | 13篇 |
1989年 | 15篇 |
1988年 | 17篇 |
1987年 | 20篇 |
1986年 | 21篇 |
1985年 | 15篇 |
1984年 | 10篇 |
1983年 | 5篇 |
1982年 | 11篇 |
1980年 | 8篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1974年 | 6篇 |
1971年 | 4篇 |
1967年 | 3篇 |
排序方式: 共有962条查询结果,搜索用时 15 毫秒
1.
J I?igo A Arce E Rodríguez D García de Viedma E Palenque M J Ruiz Serrano L Cabello F Chaves 《The international journal of tuberculosis and lung disease》2006,10(5):550-553
SETTING: Tuberculosis (TB) cases reported from nine districts of Madrid, where the percentage of immigrant population varied from 1.9% in 1996 to 12.2% in 2003. OBJECTIVE: To describe the trends in TB incidence from 1994 to 2003. DESIGN: Observational study. RESULTS: Between 1994-1995 and 2002-2003, the TB rate decreased from 48.5 (95% CI 45.8-51.1) to 23.3 per 100000 population (95% CI 21.5-25.1) (P < 0.001). The percentage of TB cases co-infected with HIV decreased from 55.9% in 1994 to 14.3% in 2003 (P < 0.001), whereas TB cases in foreigners increased from 2.6% in 1994 to 33.7% in 2003 (P < 0.001). CONCLUSION: Although the TB rates showed a marked decrease in the study period, the increasing impact of immigration contributed to slowing down the trend. 相似文献
2.
3.
L. Lima V. Arce M. J. Diaz J. A. F. Tresguerres J. Devesa 《Clinical endocrinology》1991,35(2):129-135
OBJECTIVE: The aim of this study was to investigate the effect of a single dose of clonidine on the pattern of GH release in response to a 10-hour continuous GRF infusion in normal man. DESIGN: Plasma GH was analysed in samples withdrawn at 20-minute intervals, from 0900 to 1900 h, according to the following protocols: in a control study, a placebo was given at 1000 h; in other experiments, clonidine (300 micrograms, orally) was given at 1000 h, alone or together with a continuous intravenous infusion of GRF 1-29 (0.3 micrograms/kg/h) starting at this time. In another experiment, the continuous infusion of GRF 1-29 was preceded by placebo administration at 1000 h. PATIENTS: Eight normal volunteers (four women and four men), aged 19-24 years were studied. MEASUREMENTS: Plasma GH levels were measured by RIA. Analysis of the pattern of GH secretion was performed using cluster analysis. RESULTS: Clonidine induced a slight but significant increase in plasma GH values, peaking 60 to 120 minutes later; however, no significant changes were observed in indices of total and pulsatile GH release for the whole sampling period in this study. Continuous GRF administration led to increased episodic GH secretion, by augmenting GH peak amplitude, although peak frequency was not modified. An increase in interpulse GH values was also observed during GRF infusion. Pretreatment with clonidine clearly changed the pattern of GH release during GRF infusion: the amount of GH secreted was significantly higher, the number of GH peaks significantly increased, and almost all the GH was secreted within them. CONCLUSIONS: These data concord with our previous demonstration that clonidine disrupts the hypothalamic-somatotroph rhythm by inhibiting the hypothalamic release of somatostatin. Given that clonidine pretreatment induced a more physiological episodic pattern of GRF-induced GH release, the possibility of combining clonidine and GRF therapy for short stature in children is envisaged. 相似文献
4.
Two different hepatoma cell lines were incubated for 48h with chemotherapeutic drugs cisplatin, paclitaxel and 5-FU to determine their ability to induce cytotoxicity and DNA fragmentation as well as to modify the expression of some cell death-related genes that could be involved in the resistance to therapy. We observed that cisplatin and paclitaxel induced cytotoxicity, but significant differences between both cell lines, were found only in the case of paclitaxel. At 48h, apoptosis was clearly present in Hep3B cells treated with cisplatin and HepG2 cells treated with paclitaxel. 5-FU induced cytotoxicity in both cell lines but only at higher concentrations than the other two drugs, triggering apoptosis and necrosis in HepG2 cells and only necrosis in Hep3B. When a time course was performed for the first 8h of treatment to elucidate the initial mechanism of cell death responsible for DNA fragmentation, we observed that 5-FU in Hep3B, and cisplatin in both cell lines, induces primary necrosis, whereas at the concentration tested here, paclitaxel clearly triggers apoptosis in both cell lines. HepG2 cells were weakly sensitive to 5-FU in the first 8h of treatment, so the primary mechanism of cell death was not clear, but results seem to indicate that it could be apoptosis. At 48h, Bax was not up-regulated with any of the treatments, whereas cisplatin was able to induce Bcl-xL down-regulation in both cell lines. Treatment with 5-FU also down-regulated Bcl-xL in HepG2 cells. We also measured variations in the expression of survivin, an inhibitor of apoptosis that has also been involved in mitototic catastrophe. Hep3B cells seem to show an increase in protein levels with all treatments. Exposure to paclitaxel resulted in the highest effect. In the case of HepG2 cells, there was a decrease in survivin expression when cells were treated with 5FU and paclitaxel, both treatments showing complete loss of the protein. Using an antibody that recognizes unprocessed caspase-3, we observed that the enzyme was assumingly activated in HepG2 cells treated with 5FU and paclitaxel, but only weakly after treatment with cisplatin. Hep3B cells did not show activation since the levels of the pro-enzyme remained the same as that in the control. In conclusion, the three drugs tested in this study could induce cell death, with paclitaxel being more effective inducing apoptosis. 5FU was only effective at high doses and its mechanism seems to be primarily related to necrosis in Hep3B and probably apoptosis in HepG2. Cisplatin mechanism of cell death is probably mediated by the decrease in anti-apoptotic protein Bcl-xL whereas paclitaxel and 5FU are decreasing the apoptosis inhibitor survivin. According to pro-enzyme levels, caspase-3 was only activated in HepG2 cells, whereas in the case of Hep3B cells the mechanisms of toxicity appear to be caspase-3-independent at the time and concentrations tested in this study. The resistance of Hep3B cells to death induced by chemotherapy could be related to an increase in the expression of IAP survivin, which can decrease cell response to the treatment or even switch the type of death from apoptosis to another kind, making therapy less efficient. 相似文献
5.
Mary ER O'Brien Janet Hardy Sylvia Tan Jackie Walling Brian Peters Sarah Hatty Eve Wiltshaw 《Cancer chemotherapy and pharmacology》1992,30(3):245-248
Summary A total of 16 patients with recurrent epithelial ovarian cancer were treated with sulofenur (LY 186641), a novel oral sulfonylurea. All subjects had received previous chemotherapy. Anaemia occurred in all 16 patients, 14 of whom required a blood transfusion, and 2/16 patients received methylene blue for breathlessness due to methaemaglobinaemia. Treatment was discontinued in 2/16 cases due to rising liver enzyme values, which reverted to normal on cessation of the drug. There was no nausea or alopecia. Only two minor responses were seen. Plasma drug levels were insufficient to result in antitumour activity as extrapolated from animal data. Further studies that attempt to increase the bioavailability and improve the therapeutic index are warranted. 相似文献
6.
Linkage of the MHC to familial multiple sclerosis suggests genetic heterogeneity. The Multiple Sclerosis Genetics Group 总被引:5,自引:0,他引:5
Haines JL; Terwedow HA; Burgess K; Pericak-Vance MA; Rimmler JB; Martin ER; Oksenberg JR; Lincoln R; Zhang DY; Banatao DR; Gatto N; Goodkin DE; Hauser SL 《Human molecular genetics》1998,7(8):1229-1234
Multiple sclerosis (MS) is a demyelinating autoimmune disease of the
central nervous system. While its etiology is not well understood, genetic
factors are clearly involved. Until recently, most genetic studies in MS
have been association studies using the case-control design testing
specific candidate genes and studying only sporadic cases. The only
consistently replicated finding has been an association with the HLA-DR2
allele within the major histocompatibility complex (MHC) on chromosome 6.
Using the genetic linkage design, however, evidence for and against linkage
of the MHC to MS has been found, fostering suggestions that sporadic and
familial MS have different etiologies. Most recently, two of four genomic
screens demonstrated linkage to the MHC, although specific allelic
associations were not tested. Here, a dataset of 98 multiplex families was
studied to test for an association to the HLA-DR2 allele in familial MS and
to determine if genetic linkage to the MHC was due solely to such an
association. Three highly polymorphic markers (HLA-DR, D6S273 and TNFbeta)
in the MHC demonstrated strong genetic linkage (parametric lod scores of
4.60, 2.20 and 1.24, respectively) and a specific association with the
HLA-DR2 allele was confirmed (TDT; P < 0.001). Stratifying the results
by HLA-DR2 status showed that the linkage results were limited to families
segregating HLA-DR2 alleles. These results demonstrate that genetic linkage
to the MHC can be explained by the HLA-DR2 allelic association. They also
indicate that sporadic and familial MS share a common genetic
susceptibility. In addition, preliminary calculations suggest that the MHC
explains between 17 and 62% of the genetic etiology of MS. This
heterogeneity is also supported by the minority of families showing no
linkage or association with loci within the MHC.
相似文献
7.
8.
9.
E A Lozano de Arce C W Bedrossian U K Bedrossian W Reitmeyer P Le Burgeois 《Diagnostic cytopathology》1985,1(1):23-27
Herpes simplex virus (HSV) infection constitutes an immediate threat to the neonate of pregnant women who deliver vaginally, and thus requires a rapid, specific means of diagnosis that is easily applicable to cervicovaginal smears. We applied the peroxidase-antiperoxidase technique to variously fixed, previously stained Papanicolaou smears from 60 women with HSV and 18 negative controls using an HSV-2 antibody and either diaminobenzidine (DAB) or aminoethylcarbazol (AEC) as the chromogen and Mayer's, Gill's, or Lillie-Mayer's hematoxylin as the counterstain. With Papanicolaou stain alone, there was adequate cytologic demonstration of either single cells in aggregates (11%), syncytial giant cells (40%), or both (49%) that displayed a ground-glass appearance (68%), discrete nuclear inclusions (5%), or both (28%). With the peroxidase-antiperoxidase technique, 57 of the 60 HSV specimens (95%) stained moderately or strongly positive for HSV-2, as did sections of herpetic encephalitis and esophagitis. There was no false-positive staining in any of the 18 control smears revealing koilocytosis, Chlamydia, or nonspecific vaginitis. Positivity of the immunostain was more vivid and evenly dispersed through-out the cytoplasm with AEC than with DAB, but tended to wash away with alcohol-based counterstaining. In contrast, DAB was more stable, but was positive predominantly at the cell periphery and cytoplasmic processes. Lillie-Mayer's stain provided the best counterstaining for the cytologic visualization of virocytes and accompanying inflammatory and epithelial cells, which revealed a minimal degree of atypia. The fixative used had no influence on the frequency or degree of immunopositivity of virocytes, but wet fixation with 95% alcohol or Carbowax led to less background staining than Spray-Cyte.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
10.
Mutation spectrum and genotype-phenotype analyses in Cowden disease and Bannayan-Zonana syndrome, two hamartoma syndromes with germline PTEN mutation 总被引:22,自引:1,他引:22
Marsh DJ; Coulon V; Lunetta KL; Rocca-Serra P; Dahia PL; Zheng Z; Liaw D; Caron S; Duboue B; Lin AY; Richardson AL; Bonnetblanc JM; Bressieux JM; Cabarrot-Moreau A; Chompret A; Demange L; Eeles RA; Yahanda AM; Fearon ER; Fricker JP; Gorlin RJ; Hodgson SV; Huson S; Lacombe D; Eng C 《Human molecular genetics》1998,7(3):507-515
The tumour suppressor gene PTEN , which maps to 10q23.3 and encodes a 403
amino acid dual specificity phosphatase (protein tyrosine phosphatase;
PTPase), was shown recently to play a broad role in human malignancy.
Somatic PTEN deletions and mutations were observed in sporadic breast,
brain, prostate and kidney cancer cell lines and in several primary tumours
such as endometrial carcinomas, malignant melanoma and thyroid tumours. In
addition, PTEN was identified as the susceptibility gene for two hamartoma
syndromes: Cowden disease (CD; MIM 158350) and Bannayan-Zonana (BZS) or
Ruvalcaba-Riley-Smith syndrome (MIM 153480). Constitutive DNA from 37 CD
families and seven BZS families was screened for germline PTEN mutations.
PTEN mutations were identified in 30 of 37 (81%) CD families, including
missense and nonsense point mutations, deletions, insertions, a
deletion/insertion and splice site mutations. These mutations were
scattered over the entire length of PTEN , with the exception of the first,
fourth and last exons. A 'hot spot' for PTEN mutation in CD was identified
in exon 5 that contains the PTPase core motif, with 13 of 30 (43%) CD
mutations identified in this exon. Seven of 30 (23%) were within the core
motif, the majority (five of seven) of which were missense mutations,
possibly pointing to the functional significance of this region. Germline
PTEN mutations were identified in four of seven (57%) BZS families studied.
Interestingly, none of these mutations was observed in the PTPase core
motif. It is also worthy of note that a single nonsense point mutation,
R233X, was observed in the germline DNA from two unrelated CD families and
one BZS family. Genotype-phenotype studies were not performed on this small
group of BZS families. However, genotype-phenotype analysis inthe group of
CD families revealed two possible associations worthy of follow-up in
independent analyses. The first was an association noted in the group of CD
families with breast disease. A correlation was observed between the
presence/absence of a PTEN mutation and the type of breast involvement
(unaffected versus benign versus malignant). Specifically and more
directly, an association was also observed between the presence of a PTEN
mutation and malignant breast disease. Secondly, there appeared to be an
interdependent association between mutations upstream and within the PTPase
core motif, the core motif containing the majority of missense mutations,
and the involvement of all major organ systems (central nervous system,
thyroid, breast, skin and gastrointestinal tract). However, these
observations would need to be confirmed by studying a larger number of CD
families.
相似文献