全文获取类型
收费全文 | 8250篇 |
免费 | 559篇 |
国内免费 | 30篇 |
专业分类
耳鼻咽喉 | 159篇 |
儿科学 | 353篇 |
妇产科学 | 195篇 |
基础医学 | 1111篇 |
口腔科学 | 433篇 |
临床医学 | 588篇 |
内科学 | 1845篇 |
皮肤病学 | 220篇 |
神经病学 | 563篇 |
特种医学 | 457篇 |
外科学 | 1101篇 |
综合类 | 68篇 |
预防医学 | 762篇 |
眼科学 | 106篇 |
药学 | 454篇 |
1篇 | |
中国医学 | 43篇 |
肿瘤学 | 380篇 |
出版年
2023年 | 62篇 |
2022年 | 112篇 |
2021年 | 244篇 |
2020年 | 130篇 |
2019年 | 213篇 |
2018年 | 287篇 |
2017年 | 192篇 |
2016年 | 185篇 |
2015年 | 216篇 |
2014年 | 280篇 |
2013年 | 365篇 |
2012年 | 470篇 |
2011年 | 513篇 |
2010年 | 384篇 |
2009年 | 297篇 |
2008年 | 413篇 |
2007年 | 411篇 |
2006年 | 373篇 |
2005年 | 385篇 |
2004年 | 347篇 |
2003年 | 313篇 |
2002年 | 268篇 |
2001年 | 199篇 |
2000年 | 224篇 |
1999年 | 207篇 |
1998年 | 148篇 |
1997年 | 118篇 |
1996年 | 95篇 |
1995年 | 94篇 |
1994年 | 79篇 |
1993年 | 84篇 |
1992年 | 98篇 |
1991年 | 85篇 |
1990年 | 85篇 |
1989年 | 113篇 |
1988年 | 92篇 |
1987年 | 80篇 |
1986年 | 60篇 |
1985年 | 60篇 |
1984年 | 41篇 |
1983年 | 37篇 |
1982年 | 25篇 |
1980年 | 23篇 |
1979年 | 25篇 |
1978年 | 30篇 |
1977年 | 23篇 |
1976年 | 31篇 |
1975年 | 29篇 |
1974年 | 23篇 |
1973年 | 23篇 |
排序方式: 共有8839条查询结果,搜索用时 0 毫秒
61.
The t(X;1)(p11.2;q21.2) translocation in papillary renal cell carcinoma fuses a novel gene PRCC to the TFE3 transcription factor gene 总被引:4,自引:2,他引:4
62.
Somatic mutation processes at a human minisatellite 总被引:6,自引:3,他引:6
Germline instability at human minisatellites frequently involves complex
inter-allelic transfers of repeat units usually restricted to one end of
the repeat array and apparently regulated by flanking DNA. In contrast,
nothing is known about the structural basis of somatic instability at
minisatellites. An electrophoretic size-enrichment strategy was therefore
developed at minisatellite MS32 (D1S8) to enable rare abnormal-length
mutants to be detected, validated and quantitated in blood DNA by single
molecule PCR. Structural analysis of rare mutant alleles in blood revealed
simple deletions/duplications of repeat unit blocks located at random along
the tandem repeat array, a mode of mutation completely different from that
seen in sperm. Furthermore, allele-specific suppression of sperm
instability at MS32 did not affect somatic instability. These data suggest
that conversion-based minisatellite mutation in sperm is completely
germline-specific and most likely meiotic in origin. Somatic instability
appears to occur by a separate pathway involving replication slippage or,
more likely, intra-allelic unequal crossing over.
相似文献
63.
Mutations in the TSC2 gene: analysis of the complete coding sequence using the protein truncation test (PTT) 总被引:4,自引:0,他引:4
Mutations in the TSC2 gene on chromosome 16p13.3 are responsible for
approximately 50% of familial tuberous sclerosis (TSC). The gene has 41
small exons spanning 45 kb of genomic DNA and encoding a 5.5 kb mRNA. Large
germline deletions of TSC2 occur in <5% of cases, and a number of small
intragenic mutations have been described. We analysed mRNA from 18
unrelated cases of TSC for TSC2 mutations using the protein truncation test
(PTT). Three cases were predicted to be TSC2 mutations on the basis of
linkage analysis or because a hamartoma from the patient showed loss of
heterozygosity for 16p13.3 markers. Three overlapping PCR products,
covering the complete coding sequence of mRNA, were generated from
lymphoblastoid cell lines, translated into 35S-methionine labelled protein,
and analysed by SDS-PAGE. PCR products showing PTT shifts were directly
sequenced, and mutations confirmed by restriction enzyme digestion where
possible. Six PTT shifts were identified. Five of these were caused by
mutations predicted to produce a truncated protein: (i) a sporadic case
showed a 32 bp deletion in exon 11, and a mutant mRNA without exon 11 was
produced; the normal exon 10 was also spliced out; (ii) a sporadic case had
a 1 bp deletion in exon 12 (1634delT); (iii) a TSC2-linked mother and
daughter pair had a G-->T transversion in exon 23 (G2715T) introducing a
cryptic splice site causing a 29 bp truncation of mRNA from exon 23; (iv) a
sporadic case showed a 2 bp deletion in exon 36; (v) a sporadic case showed
a 1 bp insertion disrupting the donor splice site of exon 37 (5007+2insA),
resulting in the use of an upstream exonic cryptic splice site to cause a
29 bp truncation of mRNA from exon 37. In one case, the PTT shift was
explained by in-frame splicing out of exon 10, in the presence of a normal
exon 10 genomic sequence. Alternative splicing of exon 10 of the TSC2 gene
may be a normal variant. Three 3rd base substitution polymorphisms were
also detected during direct sequencing of PCR products. Confirmed mutations
were identified in 28% of the families studied and on the assumption that
half of the sporadic cases should have TSC2 mutations, a crude estimate of
the detection rate would be 60%. This compares favourably with other
screening methods used for TSC2, notably SSCP, and since PTT involves much
less work it may be the method of choice.
相似文献
64.
N. Prats V. Briones M. M. Blanco J. Altimira J. A. Ramos L. Domínguez A. Marco 《European journal of clinical microbiology & infectious diseases》1992,11(8):744-747
In a study of central nervous system involvement in experimental listeriosis 27 Swiss CD1 mice were inoculated subcutaneously withListeria monocytogenes. Systemic infection developed, as shown by the isolation ofListeria monocytogenes and histopathological lesions in the spleen and liver. In the central nervous system a mixed inflammatory infiltration in the ventricular system, especially in the choroid plexus, and leptomeningitis were the most relevant lesions. Inflammatory lesions were associated with the presence ofListeria monocytogenes, as demonstrated by a positive anti-Listeria monocytogenes immunoperoxidase reaction within phagocytic cells. It is suggested that choroiditis and meningitis developed as a consequence of hematogenous dissemination ofListeria monocytogenes within mononuclear phagocytes and penetration of these cells into the ventricular system through the choroid plexus. 相似文献
65.
A J Marco N Prats J A Ramos V Briones M Blanco L Dominguez M Domingo 《Journal of comparative pathology》1992,107(1):1-9
The course of murine infection after intragastric inoculation of L. monocytogenes was investigated by immunocytochemical, histopathological and microbiological techniques. L. monocytogenes antigen was observed in epithelial cells of intestinal mucosa overlying Peyer's patches, but not in mucosa devoid of them. This suggests that penetration of L. monocytogenes into the host organism may take place through epithelium overlying Peyer's patches. The efficiency of bacterial penetration appeared to be low, as shown by the small amounts of L. monocytogenes antigen detected and the low counts of bacteria in organs. Gross or histopathological lesions in the intestinal tract were not observed. The presence of L. monocytogenes in spleen, liver and in maxillary and mesenteric lymph nodes, confirmed that the systemic course of infection by this route of inoculation is similar to that of the parenteral routes. The results emphasize the subclinical character of murine listeriosis by the oral route. 相似文献
66.
The present study, in consonance with recent anatomical investigations, demonstrates that activation of the nucleus parvocellularis in the rat evokes a potent hypersecretory effect in the submandibular and sublingual (S-S) salivary glands. Furthermore, electrolytic lesioning of this region in conjunction with peripheral removal of the parotid glands is followed by an increase in the number of drinking responses in the presence of dry food. Such prandial drinking behavior is only observed after total impairment of salivation (i.e., removal of the S-S + parotid glands), thus suggesting that the parvocellularis lesion led to a marked deficit in S-S salivary secretion. On the other hand, the activation of the nucleus parvocellularis was seen to have only a slight effect on parotid salivary secretion. Electrolytic lesions to this zone, when associated with peripheral removal of the S-S glands, failed to induce prandiality, suggesting that the parvocellularis nucleus exerted a low level of control over parotid salivary secretion. These results are interpreted as functional proof of the relationship between the parvocellularis reticular formation and the superior salivatory nucleus in the secretion of S-S saliva. 相似文献
67.
Detecting pre-ovulatory luteinizing hormone surges in urine 总被引:2,自引:1,他引:2
Kesner JS; Knecht EA; Krieg EF Jr; Wilcox AJ; O'Connor JF 《Human reproduction (Oxford, England)》1998,13(1):15-21
The study objectives were to determine (i) if pre-ovulatory luteinizing
hormone (LH) surges, undetected in urine by two immunoradiometric assays
(IRMA), were detectable by an ultrasensitive immunofluorometric assay
(IFMA) and (ii) the influence of creatinine adjustment on the detection and
timing of the urinary LH surges. Daily urine specimens were contributed by
healthy 25-36 year old volunteers during 14 ovulatory menstrual cycles for
an epidemiological study conducted in 1983-1985. Specimens were selected as
having been previously assayed by two IRMA without consistently detecting
LH surges. These urine specimens were remeasured using an IFMA and adjusted
for creatinine concentration. IFMA measurements revealed unambiguous LH
surges in all cycles. Adjusting IRMA urinary LH values for creatinine
concentrations revealed previously undetected LH surges in four of eight
cycles. Creatinine adjustment also altered the timing of IRMA and IFMA LH
surges by 1-5 days. These results demonstrate an IFMA that detects pre-
ovulatory LH surges in unpreserved, frozen urine from cycles where such
surges were previously undetectable. Further, creatinine adjustment can
markedly affect detection and timing of the onset and peak of the urinary
LH surge. While our analysis suggests that this adjustment improves the
validity of the LH measure, this requires further investigation.
相似文献
68.
69.
70.
Riera-Espinoza G Ramos J Carvajal R Belzares E Stanbury G Farías R Valderrama I Alvarez K Riera-González G 《Maturitas》2004,47(2):83-90
OBJECTIVES: An open study was carried out to evaluate changes in bone remodeling markers such as N-telopeptide (NTx), tartrate-resistant acid phosphatase (TRAP), total alkaline phosphatase (TAP), and bone alkaline phosphatase (BAP) during a 1-year continuous tibolone treatment in postmenopausal women. MATERIAL AND METHODS: Thirty-six postmenopausal women were recruited for receiving tibolone 2.5 mg per day for 1 year. Densitometry and determination of biochemical markers of bone metabolism in serum and urine were performed at 1, 3, 6, and 12 months. RESULTS: Comparing baseline with 12 month's values, BAP and all resorption markers decreased significantly. NTx began to decrease since the initiation of the treatment (baseline: 74.4 +/- 5.3; 1 month: 57.5 +/- 4.2; 12 months: 36.6 +/- 2.8). BAP increased at the first month (baseline: 37.3 +/- 2.1; 1 month: 42.6 +/- 3.0) but diminished in the following months (12 months: 23.1 +/- 1.5). TAP started to decrease significantly only after 6 months of treatment (baseline: 37.3 +/- 2.1; 12 months: 31.4 +/- 2.3) and TRAP after 3 months (baseline: 9.8 +/- 0.4; 6 months: 9.1 +/- 0.5; 12 months: 8.2 +/- 0.4). Normal bone mineral density at distal and ultradistal forearm was maintained during the 1-year treatment (baseline: 0.42 +/- 0.01; 12 months: 0.42 +/- 0.01 and baseline: 0.33 +/- 0.01; 12 months: 0.33 +/- 0.01, respectively). CONCLUSION: The use of tibolone 2.5 mg per day diminished progressively and significantly bone resorption and formation markers during 1-year treatment period. 相似文献